Indazoles are high value chemical building blocks used in medicinal chemistry and materials science for their distinct structural and functional features. This study details a [3+2]?cycloaddition reaction between various aryl?ketodiazoesters and ortho?(trimethylsilyl)aryl triflates under mild conditions, leading predominantly to 1?acyl?1H?indazoles. N?aryl?1H?indazoles and aryl benzoates were also observed as other products. The reaction exhibits broad functional group tolerance and scalability, making it a valuable synthetic approach. Mechanistic insights, derived from control experiments and density functional theory (DFT) calculations, elucidate the cycloaddition pathway and rationalize the formation of the products. Collectively, these findings underscore the method’s potential for synthesizing complex indazole derivatives, which hold significant promises for applications in pharmaceutical development and advanced materials research

This study focuses on fabricating a dual-active photocatalytic cartridge material for degrading dyes and antibiotics. Hence, the in-situ uniform growth of MnO2/CuO on 3D porous high surface area carbonaceous matrix, not only efficiently degrades Eriochrome Black T (EBT - 95.40 %), Loffler’s Methylene Blue (MB - 98.06 %), and azithromycin (96.50 %) within 100 min of light illumination but also reusable and stable upto 6 cycles. The mechanistic understanding based on band structure analysis, electron paramagnetic resonance technique and scavenging experiments, cumulatively explains about the participation of hydroxyl radical (•OH) at valence band of MnO2 (VBMO) and superoxide radical (•O2–) at conduction band of CuO (CBCO) in redox reactions following a Z-scheme mechanism. The theoretical studies show that the charge redistribution creates a built-in electric field between CuO-CNT-MnO2 layers, driving photogenerated electrons and holes in opposite directions, forming •O2– at CBCO and •OH at VBMO, thus enhancing degradation kinetics. The toxicity study shows 100 % cell viability with 100 minutes of dye-degraded water, 100 % bacterial viability, and healthier plants when exposed to azithromycin-degraded water, overall indicating that the degraded products are bio-compatible. A sustainable and smart prototype filter technology is demonstrated, which effectively filters 5 litres of dye/antibiotic under continuous light irradiation.

We report a novel oxidative rearrangement of the diazene moiety in 3-aryl azo indoles, leading to the formation of C3-oxo-C2-amino indoles with excellent regioselectivity. This transformation, achieved using oxone in water at ambient temperature, proceeds in good yields with broad functional group tolerance including and azaindoles. Mechanistic insights were gained through control experiments, crystal structures, and density functional theory (DFT) calculations. Experimental and theoretical photophysical studies, along with cellular uptake and colocalization experiments, demonstrate that the resulting compounds selectively bind to lipid droplets (LDs), highlighting their potential as fluoroprobes for LD detection

Perchlorate ions (ClO4 -) are prevalent contaminants in the surface, and drinking water that disrupt thyroid function by competitively inhibiting the sodium-iodide symporter (NIS), posing significant health risks. Here, fluorescence-based logic gates have been constructed by leveraging the binding interactions between a hemicyanine dye, 4-[4-(dimethylamino)-styryl]-1-docosylpyridinium bromide (DASPC22) and ?-cyclodextrin (?-CD) that could be useful to know whether ClO4 - ions in water are within the toxicity range or not. In aqueous media, DASPC22 forms nonfluorescent H-aggregates, but fluorescence is enhanced upon forming host-guest inclusion complexes with ?-CD. At low ClO4 - ions concentrations, fluorescence intensity further increases due to enhanced complex stability through hydrogen bonding. ONIOM-based quantum chemical calculations have supported this phenomenon. The enhancement of fluorescence intensity of DASPC22 in the presence of ?-CD and a low concentration of ClO4 - ions leads to the construction of a YES logic gate that would enable one to quantify ClO4 - ions' toxicity range in water. Dual-input-single-output AND and INHIBIT logic gates with low and high concentrations of ClO4 - ions, respectively, have also been constructed. The present system could be useful in addressing safety concerns related to perchlorate contamination of water

Metal doping offers a potent strategy for enhancing the optical properties and stability of CsPbCl3 (CPC) perovskites. While Mn doping has drawn attention to its unique attributes, it has failed to achieve the benchmarks set by CsPbBr3 and CsPbI3. To bridge this gap, a codoping approach involving earth-abundant and cost-effective FeCl2 has been explored in this study. PL emission peak intensity increased after codoping with various FeCl2 concentrations in Mn-doped CPC (Mn-CPC) nanocrystals. Fe2+ effectively enhances the Mn doping efficiency in CPC across 0.1–0.3 mmol concentrations by replacing some Pb2+ sites. The resultant Fe-codoped Mn-CPC nanocrystals display orange emission in hexane at 594–606 nm, boasting photoluminescence quantum yields up to 22–27%. Notably, codoped nanocrystals exhibit better photostability under ambient conditions and UV-light irradiation than Mn-CPC. The improved photoresponse characteristics induced by Fe2+ codoping highlight the potential of these nanocrystals for integration into UV–visible photodetectors and other optoelectronic devices. The electrochemical property of Fe ion-codoped Mn-CPC PNCs showed better photocurrent density results than Mn-CPC

Diarylethene photoswitches featuring azole-based diaryl units combined with benzoheteroarene ?-linkers have gained significant research interest in recent years due to their potential to achieve higher photocyclization efficiencies compared to conventional dithienylethene switches. In this work, we investigate the suitability of these photoswitches for molecular solar thermal energy storage (MOST) applications through computational modeling of their electrocyclization and cycloreversion reactions. Our calculations demonstrate that it is possible to achieve simultaneously both large energy-storage densities (0.29–0.35 MJ kg–1) and prolonged energy-storage times (half-lives of up to 124 days) under ambient conditions in dithiazolyl and dioxazolyl switches containing six distinct benzoheteroarene ?-linkers. Furthermore, isomerization stabilization energy calculations and noncovalent interaction analysis reveal that the variations in energy-storage densities and times between the azole-based and dithienylethene switches stem from differences in aromaticities of the diaryl core and ?-linker, as well as changes in noncovalent interactions. Notably, we demonstrate that the relative populations of photoreactive anti-parallel and non-photoreactive parallel conformers of the ring-open form of these switches are governed by weak intramolecular C C interactions between the two aryl rings. These findings highlight the importance of optimizing such interactions to enhance energy-storage efficiencies in MOST systems

Through comprehensive density functional theory calculations, the photodegradation mechanisms, including cis–trans isomerization, electrocyclization, and sigmatropic rearrangement reactions are investigated in indacenodithieno [3,2-b] thiophene (IT)-based non-fullerene acceptors (NFAs). Various functional group substitutions on the core (fluorine, ethyl, and cyano groups) and end groups (fluorine) of NFA are introduced to elucidate the influence of chemical modifications on photodegradation pathways. The findings reveal that the core substitution can effectively suppress electrocyclization and 1,5-sigmatropic shift reactions, which are major contributors to photodegradation. Furthermore, the electronic, excited-state, and charge transport properties of pristine and degraded products are studied to gain insights into the impact of degradation on photovoltaic parameters. The results suggest that photodegradation leads to the formation of shallow energy trap states, hindering charge transport and increasing charge recombination, ultimately affecting the power conversion efficiency of organic solar cells (OSCs). The study not only provides a comprehensive understanding of photodegradation mechanisms but also offers valuable molecular design strategies to enhance the stability of NFAs for future large-scale applications of OSCs. By establishing a clear connection between the chemical structure and photostability of NFA, this research represents a pivotal contribution to the field of organic electronics and sustainable energy technologies. © 2024 Wiley-VCH GmbH.

In order to attain high performance in single-component organic solar cells (SCOSCs), it requires the designing of light-harvesting structures that can absorb light across a wide range from visible to near-infrared (NIR) wavelengths. In this investigation, two novel dyad materials, denoted as SPS-BF-Full and SPS-BT-Full are designed and synthesized, consisting of covalently linked benzofuran (BF) and benzothiophene (BT) functionalized thiophene–diketopyrrolopyrrole (TDPP) as donor and N-methyl fullero[60]pyrrolidine as the acceptor, respectively. The incorporation of a phenyl bridge between TDPP and fullero[60]pyrrolidine enhances light absorption in SPS-BF-Full and SPS-BT-Full, resulting to a high short-circuit density (JSC). Consequently, the SCOSCs utilizing SPS-BT-Full and SPS-BF-Full attained overall power conversion efficiency (PCE) of 6.28 and 7.35%, respectively. The high photovoltaic performance of OSCs utilizing SPS-BF-Full is mainly attributed to its higher external quantum efficiency and balanced hole and electron mobility (?e/?h=1.39), along with imporved charge carrier extraction, revealing more effective charge transport in comparison to SPS-BT-Full counterparts

The critical features of atomic or molecular scalar fields can be captured by mapping their topography. The topography maps, viz., molecular electron density (MED) and molecular electrostatic potential (MESP), are successfully used to characterize the weak interactions that exist in systems ranging from small molecular clusters to large supramolecular systems. Topography mapping mainly involves identifying and characterizing their critical points (CPs). These CPs are extremely useful for describing the nature of weak interactions and quantifying the strength of interaction. The first part of the chapter delineates fundamental concepts related to MED and MESP. Later, the usefulness of MED and MESP analyses for understanding weak interactions is demonstrated by taking various molecular complexes.

Herein, we demonstrated the optimization of a blue LED (450 nm) induced C-C bond formation between various aryl and heteroaryl aldehydes with 1,4-quinones at room temperature in ethyl acetate using Design of Experiments (DoE). This reaction was conducted within a flow (micro and milli-fluidic) device using a millifluidic meandering channel reactor (MC2), resulting in a library of diversely substituted diaryl ketones with moderate to good yields. Control experiments and density functional theory (DFT) based computational investigations were performed to elucidate the reaction mechanism

Herein, we report an expedient synthesis of aryl sulfonyl ureas 4 and 5 from N-amino pyridinium ylides and aryl isocyanates. N-Aminopyridinium ylides 3 are synthesized via blue light-emitting diode irradiation of pyridine/isoquinoline and appropriate iminoiodinanes. The strategy involved a hitherto unknown carboamination of imine moieties (of aryl isocyanates) via a three-component reaction of pyridine derivatives/isoquinoline 1, N-aryl sulfonyl iminoiodinanes 2, and numerous aryl isocyanates at room temperature in 2-methyl tetrahydrofuran to afford the target compounds in moderate to excellent yields. N-Arylpyridinium ylides 3 (as intermediates) undergo a [3+2] cycloaddition with the aryl isocyanates followed by the aromatization of the pyridine/isoquinoline moiety to afford compounds 4. On the basis of the substitution pattern among the reactants, in some cases pyridine extrusion occurs during the reaction to afford depyridinylated aryl sulfonyl ureas 5. In general, isocyanates are used as dipolarophiles in [3+2] cycloaddition reactions. However, regioselective amino pyridylation of these species is a first. Control experiments and density functional theory calculations elucidate the reaction mechanism. The batch process of the protocol could be seamlessly transferred to the photoflow synthesis

The development of small-molecule organic solar cells with the required efficiency depends on the information obtained from molecular-level studies. In this context, 39 small-molecule donors featuring isoindigo as an acceptor moiety have been meticulously crafted for potential applications in bulk heterojunction organic solar cells. These molecules follow the D2-A-D1-A-D2 and D2-A-?-D1-?-A-D2 framework. Similar molecules considered in the previous experimental study (molecules R1 ((3E,3?E)-6,6?-(benzo[1,2-b:4,5-b?]dithiophene-2,6-diyl)bis(1,1?-dimethyl-[3,3?-biindolinylidene]-2,2?-dione)) and R2 ((3E,3?E)-6,6?-(4,8-dimethoxybenzo[1,2-b:4,5-b?]dithiophene-2,6-diyl)bis(1,1?-dimethyl-[3,3?-biindolinylidene]-2,2?-dione))) have been chosen as reference molecules. Molecules with and without ?-spacers have been considered to understand the impact of the length of the ?-spacer on intramolecular charge-transfer transitions and absorption properties. A detailed investigation is carried out to establish the relationship between the structure and photovoltaic parameters using density functional theory and time-dependent density functional theory methods. The newly developed molecules exhibit better electronic, excited-state, and charge transport properties than the reference molecules. Additionally, model donor-acceptor interfaces are constructed by integrating the designed donor molecules with fullerene/nonfullerene acceptors. The electronic and excited-state properties of these interfaces are rigorously evaluated. Results elucidate that the donor comprising of isoindigo-bithiophene-pyrroloindacenodithiophene (IIG-T2-PIDT) emerges as a promising candidate for bulk heterojunction solar cells based on nonfullerene acceptors. This research provides systematic design strategies for the development of small-molecule donors for organic solar cells. © 2024 American Chemical Society.

Utilizing hole-transporting materials (HTMs) to extract and transport holes from perovskite materials to the electrode remains essential in most perovskite solar cell (PSC) architectures. Developing cost-effective and efficient HTMs is essential for advancing PSC technology. We have synthesized a novel HTM, TPA-IDT-TPA, which has an extended fused ring as the core moiety called indacenodithiophene (IDT) and p-methoxy triphenylamine (p-mTPA) as terminal groups. TPA-IDT-TPA exhibits appropriate frontier molecular orbital (FMO) energy levels that match perovskite materials. Density functional theory (DFT) simulations were performed to comprehend the electronic, excited-state, and charge transport properties. The DFT results indicate that the extended ?-conjugation, rigidity, and the central core ring of the HTM enhanced the ?-? stacking, contributing to efficient charge transport. The PSC constructed with TPA-IDT-TPA achieves a device efficiency of 8.34%, with high values of JSC and VOC, which can be further enhanced through molecular optimization. © 2024 International Solar Energy Society

Understanding thermally activated delayed fluorescence (TADF) in solid-state environments is crucial for practical applications. However, limited research focuses on how the medium affects TADF properties of hot-exciton-based emitters. In our study, we calculated and compared reverse intersystem crossing, radiative, and non-radiative decay rates of TADF emitters in gas, solvent, and solid phases. The designed emitters have a donor-acceptor-donor (D-A-D) structure, with donors such as triphenylamine (TPA) and diphenylamine thiophene (ThPA), combined with acceptors such as benzothiadiazole (BT), pyridine thiadiazole (PT) and thiadiazolobenzopyridine (NPT). We model the solvent and solid phases with the polarizable continuum model (PCM) and quantum mechanical/molecular mechanics (QM/MM) methods, respectively. Using density functional theory (DFT) and time-dependent DFT, we analyze how TADF emitters? geometrical, electronic, and excited-state properties vary in these phases. Our results show that the solid-state environment significantly influences the geometry and TADF properties of emitters. In the presence of solid medium, our study indicates that non-radiative decay rates tend to be slower. On the other hand, radiative emission rates were found to be less influenced by the properties of the surrounding medium. Overall, our study connects emitter chemical structure and the surrounding environment‘s impact on excited-state characteristics and photochemical properties.

Glyphosate (Gly) is a massively utilized toxic herbicide exceeding its statutory restrictions, causing adverse environmental and health impacts. Engineered nanomaterials, even though are integral to remediate Gly, their practical use is limited due to time and energy driven purifications, and negative environmental impacts. Here, a 3D wide area (~1.6 ± 0.4 cm 2 ) Cu 2 O nanoparticle supported biotemplate is designed using fish-scale wastes as a sustainable approach for the ultra-efficient and selective hand-remediation of Gly from real-time samples from agro-farms. While the innate metal binding and reducing ability of collagenous scales aided self-synthesis cum grafting of Cu 2 O, the selective binding potential of Cu 2 O to Gly facilitated its hand-retrieval; as assessed using optical characterizations, Fourier transform infrared spectroscopy, thermogravimetric analysis and liquid chromatography mass spectrometry. Optimization studies revealed extractions of diverse pay-loads of Gly between 0.1 ?g/mL to 40 ?g/mL per 80 mg biotemplate grafted with ~6.354 ?g of sub-5 nm Cu 2 O and was exponential to the number of Cu 2 O@biotemplates. Even though pH and surfactant didn't have any impact on the adsorption of Gly to the Cu 2 O@biotemplates, increase in the ionic strength led to a drastic increase in the adsorption. Density function theory simulations unveiled the involvement of phosphonic and carboxylic groups of Gly for interaction with Cu 2 O with a bond length of 1.826 Å and 1.833 Å, respectively. Overall, our sustainably generated, cost-efficient, hand-retrievable Cu 2 O supported biotemplate can be generalized to extract diverse organophosphorus toxins from agro-farms and other sewage embodiments. Glyphosate is an excessively applied herbicide with potent health hazards and carcinogenicity. Thus, a hand removable Cu 2 O-supported biotemplate to selectively and efficiently remediate glyphosate from irrigation water is developed.

Green Hydrogen emerges as a promising energy solution in the quest for achieving Net Zero goals. The application of particulate semiconductors in photocatalytic water splitting introduces a potentially scalable and economically viable technology for converting solar energy into hydrogen. Overcoming the challenge of efficiently transferring photoelectrons and photoholes for both reduction and oxidation on the same catalyst is a significant hurdle in photocatalysis. In this context, we introduce highly efficient crystalline elemental boron nanostructures as photocatalysts, employing a straightforward and scalable synthesis method yield green hydrogen production without the need for additional co-catalysts or sacrificial agents. The resulting photocatalyst demonstrates stability and high activity in H 2 production, achieving over 1 % solar-to-hydrogen energy conversion efficiency (>15,000 ?mol. g ?1.h ?1 ) during continuous 12-h illumination. This efficiency is credited to broad optical absorption and the crystalline nature of boron nanostructures, paving the way for potential scale-up of reactors using crystalline boron photocatalysts.

In our study, we aimed to enhance the optoelectronic properties of corannulene through functionalization for use as a non-fullerene acceptor (NFA) in organic solar cells. To achieve this, we designed new corannulene derivatives by introducing various electron-donating and electron-withdrawing groups onto the corannulene core. Geometric, electronic, optical, and charge transport properties of newly designed molecules are analyzed using long-range corrected density functional theory methods. The potential NFA is identified by conducting extensive analysis, such as light absorption properties, ground-state dipole moments, and the energy difference between LUMO and LUMO+1 orbitals. Also, a model donor–acceptor interface is constructed by considering PTQ10 oligomer as the donor and corannulene derivatives as acceptors. Charge-transfer states and exciton dissociation processes are analyzed at the polymer chain and NFA interface. Overall, the results obtained from this study can provide useful guidance in designing high-performing NFAs.

The all-carboatomic ring, cyclo[18]carbon (C 18 ), has the potential to act as an electron acceptor due to promising electronic and optical properties. In this study, we first illustrated the geometrical, electronic, and excited-state properties of C 18 using various hybrid and long-range corrected density functional theory (DFT) methods. Further, we studied the nature of intermolecular interactions between dimers of C 18 to gain insights into packing configurations of cyclo[18] in dimer and trimer configurations. Also, using the state-of-the-art DFT methods, we have reported the thorough characterization of the lowest excited-state (i.e. charge-transfer state) in various donor-acceptor model complexes based on pentacene and C 18. We established an interplay between the molecular packing of C 18 and pentacene molecules on the energy of charge transfer state. All these results could help in the designing of more efficient organic solar cells.

An operationally simple mechanochemical reaction between iminoiodinanes with numerous cyclic 2°-amines such as morpholine, piperidine, pyrrolidine, thiomorpholine, N-Boc diazepine and N-Boc piperazine has been reported to afford N-sulfonyl amidines in moderate to excellent yield. The N-sulfonyl transfer reaction happens in a ball mill apparatus (RETSCH 400™) with three 5 mm stainless steel (ss) balls in a 5 mL stainless steel (ss) reaction jar with 2-methyl tetrahydrofuran as liquid assisted grinding auxiliary (LAG). This metal catalyst-base free synthesis with minimal solvents (as LAGs) demonstrated an efficient N-sulfonyl transfer reaction from iminoiodinanes. N-sulfonyl amidines are ubiquitous building blocks present in natural products and drug intermediates. Control experiments and computational studies based on density functional theory (DFT) calculations were performed to gain deeper insight into the mechanism.

Herein we have reported an expedient di-functionalization of such versatile scaffolds. By harnessing an under explored reactivity of N-aminopyridinium ylides, we have developed an aminopyridylation of N-substituted maleimides and 1, 4-quinones at room temperature in 2-methyl THF without any external reagents. The [3+2] cycloaddition of N-aminopyridinium ylides generate the corresponding cycloadduct with various maleimides and 1, 4-quinone substrates, which rapidly undergoes oxidation at the alkene moiety under open air, inducing a considerable driving force, thermodynamically, to facilitate aromatisation of the pyridine and a subsequent homolytic cleavage of the N?N bond to generate the desired 2, 3-aminopyridylated products in good to excellent yield. Experimental and computational studies clarify the reaction mechanism.

An expedient and operationally convenient mechanochemical synthesis of aryl/heteroaryl N-sulfonyl imines is reported by reacting iminoiodinanes with numerous aryl/heteroaryl benzyl alcohols in ball milling apparatus (RETSCH 400™) with three 5 mm stainless steel (ss) balls in a 5 mL stainless steel (ss) reaction jar. CHCl (? = 0.2-0.4 ?L mg) was used as a liquid assisted grinding (LAG) auxiliary. This metal catalyst- and base- free synthesis with nominal amounts of solvents (as LAGs) demonstrated an efficient N-sulfonyl transfer reaction from iminoiodinanes to afford the desired compounds in moderate to good yields. Substituted N-sulfonyl imines are crucial as standalone natural product building blocks and drug intermediates as well as precursors of sulfonamides which have been involved in potential small molecule therapy in many therapeutic programs. The putative mechanisms of the transformations are discussed based on control reactions and DFT calculations.

An effort has been made to analyze the aromaticity of oligomers of phenylenes and thiophenes, with the presence and absence of linkers using Nucleus-Independent Chemical Shift (NICS) as a descriptor. The relation between HOMO–LUMO gaps, reorganization and excitation energies with respective NICS values has been employed to develop a structure-aromaticity-conjugation spectroscopy relationship (SACSR). Results show that HOMO–LUMO gaps/excitation energies of various model systems exhibit linear relationships with the inverse of the NICS values, indicating the possible existence of the SACSR.

Developing near-infrared (NIR) TADF emitters is challenging due to the inherent energy gap law. In this work, we designed a set of twelve donor-acceptor1-acceptor2 (D-A1-A2) type NIR pure organic emitter molecules that contain a strong donor (triphenylamine (TPA)), a cyano group substituted anthrathiadiazole (AZ) unit as A1, and fused aromatic/heterocyclic molecules as the A2 unit. The strength of the acceptor part A2 is altered by introducing electron-withdrawing groups (-H, -F, -CN). We studied their geometrical, electronic, and excited state properties using Density functional theory (DFT) and time-dependent DFT methods. Comprehensive analysis of excited state properties obtained from computational methods such as the energy gap between singlet and triplet excited states (?E), spin-orbit coupling (SOC) values, the nature of singlet and triplet excited states, rates of reverse intersystem crossing (k), and radiative and non-radiative emissions (k and k) are conducted to acquire insights into the NIR emission in the studied molecules. Our calculated results show that the molecules should possess hybrid localized and charge transfer (HLCT) character dominated by Frenkel-type excitation (LE) in the lowest singlet excited state to achieve faster k. Furthermore, the strong donor, AZ unit, and moderate acceptor A2 unit provide smaller energy gaps between singlet and triplet states with reasonable SOC values in the higher excited states. In our study, we identify multiple hot-exciton channels to up-convert dark triplet excitons into bright singlet excitons, which might improve the exciton utilization efficiency.

The electron acceptor materials in organic solar cells (OSCs) play an essential role in enhancing power conversion efficiency (PCE). Although Y6-based nonfullerene acceptors (NFAs) have shown fascinating experimental progress, molecular engineering is an effective strategy for further improvement of PCE. Herein, a series of Y6-based symmetric and asymmetric NFAs are designed using the Y6-based core with various end-group units. The impact of end group units on geometric, electronic, and excited state properties of NFAs is studied using state-of-the-art density functional theory methods. Various selection criteria are used to screen potential NFAs among 18 newly designed NFAs. The interfacial electronic properties between conjugated polymer and NFAs are thoroughly studied in the excited state to analyze the potentiality of screened NFAs. More importantly, the screened asymmetric NFAs have shown improved charge mobilities with a lower charge recombination rate than prototype FRY6. It is noticed that screened NFAs have multiple charge transfer pathways through direct excitation, hot excitons, and intermolecular electric field mechanisms. Overall, the results obtained from this computational study give useful guidance for developing NFAs for high-performance OSCs.

A systematic study on the design and development of corannulene-based thermally activated delayed fluorescence (TADF) emitters using density functional theory methods is carried out. Benzene, benzopyrazine, difluoro-benzopyrazine, benzene-1,2-dithiol, and tetrasulfone are introduced on corannulene bowl as electron-withdrawing groups to alter the electron-accepting property of corannulene. Three different donors, viz., carbazole, phenoxazine, and 5,10-dihydrophenazine are substituted on the rim position of corannulene to alter the absorption properties. The relationship between chemical structure and TADF property is established by evaluating the dihedral angle between donor and acceptor units, spin–orbit coupling (SOC) values, the energy difference between singlet-triplet excited states (?E), and rates of reverse intersystem crossing (k). The newly designed TADF emitters show absorption in the blue to near-IR regions depending on the strength of the donor and acceptor moieties. Careful analysis of these properties delineates the relationship between SOC values and the nature of the excited states, which is crucial for achieving high k.

A comparative new strategy to enhance thermally activated delayed fluorescence (TADF) of through-space charge transfer (CT) molecules in organic light-emitting diodes (OLEDs) is investigated. Generally, TADF molecules adopt a twisted donor and acceptor structure to get a sufficiently small ?E and a higher value of the spin-orbit coupling matrix element (SOCME). However, molecules containing donor-phenyl bridge-acceptor (D-p-A) units and featuring ?-stacked architectures have intramolecular CT contribution through space and exhibit high TADF efficiency. We have explored the insights into the TADF mechanism in D-p-A molecules using the density functional theory (DFT) and time-dependent DFT methods. The calculated optical absorption and ?E values are found to be in good agreement with available experimental data. Interestingly, we found the origin of the SOCME to be the twisted orientation of the donor and bridge moieties. Also, we predicted similar molecules with enhanced OLED efficiency with different substitutions.

We report herein a design strategy to improve the hole mobility of D-A-D-based hole transport material (HTM) by modifying the accepting core of the reference HTMs based on triphenylamine (TPA) and bithieno thiophene (BTTI) units. Eight HTMs are designed by replacing the BTTI unit in BTTI-TPA HTM with several commonly available diones and imides as acceptors. The structural, electronic, optical, and charge transport properties are studied using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. The designed molecules are extensively examined for their structural, electronic, and absorption properties to extract the features that improve their hole mobility using the MPW1PW91/6–31 g(d,p) method. We identified four carefully designed BTTD-TPA, DBTT-TPA, NDTTI-TPA, and NDTI-TPA molecules as the most promising HTMs. This work exemplifies the role of the methyl group on electron acceptors on hole reorganization energies. Results obtained from this study provide valuable guidelines for designing efficient HTMs.

The inadequate fossil fuel resources and their impacts on the global environment are the reason for the inclination of researchers to improve clean energy technologies. Using fuel cells, the chemical energy can directly transform into electrical energy with high efficacy. Hydrogen is the most ensuring alternative for fossil fuel, but its storage is a prime issue. This chapter overviews hydrogen storage studies on a series of molecules, cages, and clusters. We describe how the nature of binding between hydrogen molecule and storage materials impact the absorption and desorption properties. We then discuss explicit examples of various hydrogen storage materials and their hydrogen storage capacities.

An n-type conjugated polymer based on diazaisoindigo (AIID) and fluorinated thiophene units is introduced. Combining the strong electron-accepting properties of AIID with backbone fluorination produced gAIID-2FT, leading to organic electrochemical transistors (OECTs) with normalized values of 4.09 F cm V s and a normalized transconductance (g) of 0.94 S cm. The resulting OECTs exhibit exceptional operational stability and long shelf-life in ambient conditions, preserving 100% of the original maximum drain current after over 3 h of continuous operation and 28 days of storage in the air. Our work highlights the advantages of integrating strong electron acceptors with donor fluorination to boost the performance and stability of n-type OECTs.

?-Conjugated open-shell diradicaloid molecules have various applications in organic electronics. Herein, we have computationally designed 20 diradicaloids. The designed diradicaloids consist of a ?-bridge flanked between two carbene-derived end groups. We describe how the diradicaloid property of these molecules can be tuned through the choice of carbene end groups and ?-bridge. We quantified the diradical character of newly designed molecules using diradical indices (Y) and (Y), the fractional occupation number weighted electron density (N), and singlet–triplet energy gaps (?E). The performance of a wide range of density functional theory (DFT)-based methods is validated using complete active space self-consistent field (CASSCF) results. Global hybrid functional BHandHLYP provides the best accuracy among all DFT methods. Our results indicate that several diradicaloids are promising materials for organic electronics.

This article describes the synthesis and structural property investigation of two new mononuclear Co(II) complexes of 8-hydroxyquinoline derived flexible tridentate N,O,N'- (L I ) and tetradentate N,O,O',N'-ligands (L II ). The reactions were carried out between CoCl 2.6H 2 O and the respective ligands in methanol to obtain the complexes CoL I Cl 2 and CoL II Cl 2 in good yields. The complexes are characterized by elemental analysis, mass, IR spectroscopy, and single-crystal X-ray diffraction. The molecular structure of CoL I Cl 2 shows distorted trigonal bipyramidal coordination geometry with the structural index parameter ? =  0.83. The apical positions are occupied with the quinoline O- and one terminal Cl-atom, whereas the equatorial positions are held by the two N-atoms and the second Cl-atom. In contrast, CoL II Cl 2 has a slightly distorted octahedral structure with all the donor atoms of the chelating ligand L II holding the equatorial positions with the two-terminal Cl-atoms at the apical positions. Electronic structure calculations are used to evaluate the geometrical, electronic, and magnetic properties of these complexes. Non-periodic calculations used to simulate molecules indicate a strong d ? -p ? bonding between Co and ligands. The crystal packing from both the solid-state structures revealed further stability of the molecule via weak non-covalent interactions through ?.… ? stacking between quinoline rings and C–H.… Cl hydrogen bonding. A detailed comparison between the geometric parameters of CoL 1 Cl 2 and CoL II Cl 2 are reported. In addition, the comparison of selected structural parameters between a range of transition metal quinolates from the literature are given. Periodic calculations to simulate crystals using B3LYP hybrid functional predicts both the crystalline structures to be magnetic insulators.

Here we report how the chemical functionalization of the bridge molecule influences the electronic properties of conjugated terthiophene and the electronic coupling, i.e., the linkage between molecule and electrode, using density functional theory (DFT) methods. Furthermore, we explore the modulation in electron transport properties of molecular junctions with various functional derivatives utilizing a combination of DFT and electron transport non-equilibrium Green’s function (NEGF) calculations.

We have investigated the structure and the stability of ternary complexes, made up of an extended aromatic ?-surface that simultaneously interacts with cation and anion on the opposite faces of the aromatic ?-cloud. To understand the influence of the role of aromatic surfaces in the ternary complexes, we have considered various linear and circular polycyclic aromatic hydrocarbons (PAHs) as model systems for the extended ?-electron surface. The interplay between the structure, stability, and cooperativity is studied using density functional theory (DFT) methods. Furthermore, the nature of the interaction, energetics, and origin of cooperative effects in the ternary complexes are characterized by using atoms in molecules (AIM), nucleus independent chemical shift (NICS), and energy decomposition analyses (EDA). Results obtained from these calculations unravel the cooperative effects present in the ternary complexes and the interplay between cation···? and anion···? interactions when they coexist in the same system.

Organic synaptic transistors are considered to be one of the most promising device concepts for neuromorphic systems. However, repressively low memory retention and high-temperature instability greatly preclude the development and real-world application of organic synaptic transistors. Herein, we reported three conjugated polymers based on a bithiophene-thienothiophene backbone and the traditional ethylene glycol (EG) chains substituted by more hydrophobic propylene glycol (PG) and butylene glycol (BG) counterparts for three-terminal organic neuromorphic memory devices (TONMD). The resulting TONMD exhibits superior viability in ambient and high-temperature environments. BG chain-based p(b2T-TT) show ultra-long memory retention of over 10 3 s and large analog switching range (>10 ×) at 180 °C, which represents the record-high high-temperature resilience for reported TONMD to date. They also demonstrated excellent endurance of over 10 5 write-read operations and ultra-high ambient stability with 96 % of its original conductance after 3 months. Data of molecular dynamic simulations and microstructure show that the superior high-temperature resilience and ambient stability originate from more rigid conformation and stable morphology with the increased hydrophobicity of the PG and BG functionalities. Overall, rational design of oligoether side-chains will boost the device's dual high-temperature and ambient stability without compromising synaptic function and provide promising strategies for high-temperature neuromorphic applications.

We have designed a series of new conjugated donor–acceptor-based macrocyclic molecules using state-of-the-art computational methods. An alternating array of donors and acceptor moieties in these macrocycle molecules are considered to tune the electronic and optical properties. The geometrical, electronic, and optical properties of newly designed macrocyclic molecules are fully explored using various DFT methods. Five conjugated macrocycles of different sizes are designed considering various donor and acceptor units. The selected donor and acceptors, viz., thiophene (PT), benzodithiophene (BDT), dithienobenzodithiophene (DTBDT), diketopyrrolopyrrole (DPP), and benzothiazole (BT), are frequently found in high performing conjugated polymer for different organic electronic applications. To fully assess the potential of these designed macrocyclic derivatives, analyses of frontier molecular orbital energies, excited state energies, energy difference between singlet–triplet states, exciton binding energies, rate constants related to charge transfer at the donor–acceptor interfaces, and electron mobilities have been carried out. We found significant structural and electronic properties changes between cyclic compounds and their linear counterparts. Overall, the cyclic conjugated D–A macrocycles’ promising electronic and optical properties suggest that these molecules can be used to replace linear polymer molecules with cyclic conjugated oligomers.

We have designed 56 new non-fullerene acceptors (NFAs) by rational design of end-cap manipulation and core modification using density functional theory methods. Geometrical, electronic, and excited state properties of these newly designed molecular are thoroughly characterized using the state-of-the-art density functional theory methods. The influence of end-cap groups on various core units is studied by comparing the absorption wavelengths, lowest excitation energies, ground-state dipole moments and, excited state dipole moments. Results obtained from these analyses reveal the importance of choosing the right combination of end-cap and core units. The potential NFAs are screened using selection criteria such as energy gap between the LUMO of polymer donor and the LUMO of NFA, based on the energy difference between LUMO and LUMO + 1 of NFAs, energy gap between the HOMO of polymer donor and LUMO of NFA, dipole moments, and quadrupole moments of NFA. Furthermore, donor–acceptor interfaces are constructed using potentials NFAs and the PM6 polymer donor. Charge-transfer state, exciton dissociation, and charge separation processes are analyzed at the polymer/NFA interfaces. Overall, results obtained from these analyses provide valuable guidelines for designing potential NFA that could enhance photovoltaic devices' efficiency.

Herein, we report a copper/amine catalyzed stereoselective addition of alkynes to ketenimine intermediates generated in situ from the sulfonyl azide-alkyne cycloaddition cascade for the stereoselective synthesis of (Z)-1,3-enynes. Significantly, for the first-time, enamine intermediates generated in the copper-catalyzed sulfonyl azide-alkyne cycloaddition reactions have been successfully trapped and isolated as the products. Density functional theory computations have also been performed and found to be consistent with the observed experimental stereoselectivity.

Despite the recent breakthroughs in the TADF process, more research is needed to understand its mechanism and develop rational molecular designs for structures with higher efficiencies and quantum yield. Hot exciton-based TADF materials, like traditional (cold) TADF, can effectively utilize singlet and triplet excitons, theoretically resulting in 100% IQE. However, in contrast to cold TADF (from low-lying T to S), the RISC process in hot TADF occurs from high-lying triplet to singlet excited states (from T(m > 1) to S(n > 1)). However, designing materials that satisfy conditions for hot exciton formation, such as large triplet spacing in lower states and a small singlet-triplet gap in higher states, remains a difficult job. In this study, we explore and analyze the fundamental concepts of molecular design and suggest a design strategy by establishing structure-property relationships for hot-TADF molecules using density functional theory methods. This study could lead to new insights into molecular design approaches for organic materials with many hot exciton channels, which could lead to better exciton utilization.

Metal nanoclusters (NCs) composed of the least number of atoms (a few to tens) have become very attractive for their emerging properties owing to their ultrasmall size. Preparing copper nanoclusters (Cu NCs) in an aqueous medium with high emission properties, strong colloidal stability, and low toxicity has been a long-standing challenge. Although Cu NCs are earth-abundant and inexpensive, they have been comparatively less explored due to their various limitations, such as ease of surface oxidation, poor colloidal stability, and high toxicity. To overcome these constraints, we established a facile synthetic route by optimizing the reaction parameters, especially altering the effective concentration of the reducing agent, to influence their optical characteristics. The improvement of the photoluminescence intensity and superior colloidal stability was modeled from a theoretical standpoint. Moreover, the as-synthesized Cu NCs showed a significant reduction of toxicity in both in vitro and in vivo models. The possibility of using such Cu NCs as a diagnostic probe toward C. elegans was explored. Also, the extension of our approach toward improving the photoluminescence intensity of the Cu NCs on other ligand systems was demonstrated.

Rigid-rod conjugated polymers contain only double-bond linkers instead of single bonds between the monomer linkages along the backbone. These polymers exhibit exceptional optoelectronic properties and promising device performances owing to their unique structures. Yet, such polymers are still very limited and little is known about their structure-property relationship so far. Herein, we have designed and synthesized a series of novel rigid-rod semiconducting polymers containing fused electron-deficient perylene diimides and isoindigo units through an inexpensive and high atom-economy method. Furthermore, the acid-mediated aldol condensation reactions do not involve any toxic reagents or transition metal catalysts. Most importantly, these polymers are isomerically pure unlike previously reported PDI polymers. The energy levels and optoelectronic properties of these polymers are tuned via adopting a molecular strategy of acene size optimization and heteroatom substitution on the variable lactone or lactams. All electron-deficient character endowed them with low-lying LUMOs, and electron transport in solution-processed thin film transistor devices has been realized using two of the polymers. Therefore the rigid-rod and fused semiconducting polymers reported here extend the scope of aldol polymerization and provide a remarkable platform for fundamental optoelectronic investigations and material innovation in the area of organic (bio)electronics.

We have investigated the electronic structure and electrical properties of sputter-deposited high-k dielectrics grown on p-GaAs substrate with post-deposition annealing at 500 °C/N 2 ambient. Capacitance-voltage results show that co-sputtered amorphous-HfTiO 2 alloy dielectric can reduce interfacial dangling bonds. HRTEM and AR- X-ray photoelectron spectroscopy results confirmed the formation of a thin interfacial layer during sputter deposition. At the atomistic level, the surface reaction and electronic interface structure were investigated by density-functional theory (DFT) calculations. Using the HSE functional, theoretical calculations of bulk HfO 2, a-TiO 2, and HfTiO 2 band gaps are found to be 5.27, 2.61, and 4.03 eV, respectively. Consequently, in the HfTiO 2 /GaAs interface, the valance band offset is found to be reduced to 1.04 eV compared to HfO 2 /GaAs structure valance band offset of 1.45 eV. Reduction in border trap density (~10 11 V/cm 2 ) was observed due to Ti atoms bridging between As-dangling bonds. The angle-resolved XPS analysis further confirmed Ti-O-As chemical bonding with very thin (~20 Å) dielectric layers.

Lithium-sulfur (Li S) batteries are emanating as the next generation alternatives for rechargeable batteries. However, the loss of capacity and self-discharge due to the dissolution of lithium polysulfides hinders their practical applications. In this study, we performed density functional theory simulations to explore the importance of carbon nanotubes (CNTs) as possible anchoring channels to immobilize soluble lithium polysulfides (Li 2 S 2n, where n = 2,3, and 4). We quantitatively investigated the interplay between confinement effects and interaction energy of Li 2 S 2n species with CNT to address the shuttling effect. Our results demonstrate that the interaction between CNTs and lithium polysulfides is governed by electrostatic interactions. Based on the interaction energies, Charge transfer analysis, and density of states, we found that CNTs facilitate the immobilization of Li 2 S 2n. Results obtained from this study will provide useful guidelines to improve the performance of Li S batteries.

Van der Waals type forces are generally responsible for the stability of conjugated polymer–acceptor complexes, and no charge transfer is observed in the ground state. Electron transfer generally occurs from donor materials to acceptor materials via photoinduced electron transfer. Here, we report a partial ground-state charge transfer in the all-polymer donor–acceptor interface using density functional theory-based methods such as long-range corrected ?B97XD and hybrid meta exchange–correlation M06 functionals. These methods are also used to evaluate the geometrical and electronic properties of conjugated polymers in the neutral and charged states.

We have attempted to gain insights into the impact of alkoxy side-chains substituted on the end group of the non-fullerene acceptor. It has been shown by experimental studies that the length and position of these alkoxy side-chains substantially influence the power conversion efficiencies of solar cell devices. A detailed analysis has been made on how the length of the alkoxy side-chains impact the molecular packing and electronic and optical properties of conjugated polymers and non-fullerene acceptor blends using quantum chemical methods. The results obtained from this study provide information on why a particular alkoxy side-chain results in better device efficiencies.

Due to their advantages of being low-cost and light weight, and having mechanical flexibility, great attention has been focused on ?-conjugated organic semiconductors. Many high-performing materials have been developed in the past decade. However, constructing electron-deficient ladder-type conjugated systems is far more challenging than constructing electron-rich systems. We have successfully synthesized a series of larger and extended novel electron-deficient aza-isoindigos (AIID-12, FAIID-12, and AIID-14) with up to 14 rings. Terminal fluorine atoms and the fusion of an additional naphthalene ring are also introduced to compare the properties of the resulting compounds to those of phenyl aza-isoindigos. Compared with isoindigo, the absorption spectra of AIID-12, FAIID-12, and AIID-14 extend into the NIR region at 900 nm due to their extended conjugation systems. These fused aza-isoindigo conjugated systems exhibit excellent solubility, highly planar backbones, substantial crystallinity, tunable conjugation lengths, and optoelectrical properties. The more extensive conjugated system with higher highest occupied molecular orbital (HOMO) and unchanged lowest unoccupied molecular orbital (LUMO) energy levels shows a narrow band gap and near-infrared absorption. Thus, the enhanced electron affinities (EAs) can facilitate the realization of electron-transport properties. As a result, OTFT devices based on AIID-14 exhibit a hole mobility of 0.076 cm2 V-1 s-1 and electron mobility of 0.003 cm2 V-1 s-1. Our results demonstrate the great potential of these aza-isoindigo systems for small-molecule semiconductor use. This journal is

Single-atom metal (SA-M) catalysts with high dispersion of active metal sites allow maximum atomic utilization. Conventional synthesis of SA-M catalysts involves high-temperature treatments, leading to low yield with a random distribution of atoms. Herein, a nature-based facile method to synthesize SA-M catalysts (M = Fe, Ir, Pt, Ru, Cu, or Pd) in a single step at ambient temperature, using the extracellular electron transfer capability of Geobacter sulfurreducens (GS), is presented. Interestingly, the SA-M is coordinated to three nitrogen atoms adopting an MN on the surface of GS. Dry samples of SA-Ir@GS without further heat treatment show exceptionally high activity for oxygen evolution reaction when compared to benchmark IrO catalyst and comparable hydrogen evolution reaction activity to commercial 10 wt% Pt/C. The SA-Ir@GS exhibits the best water-splitting performance compared to other SA-M@GS, showing a low applied potential of 1.65 V to achieve 10 mA cm in 1.0 M KOH with cycling over 5 h. The density functional calculations reveal that the large adsorption energy of HO and moderate adsorption energies of reactants and reaction intermediates for SA-Ir@GS favorably improve its activity. This synthesis method at room temperature provides a versatile platform for the preparation of SA-M catalysts for various applications by merely altering the metal precursors.

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Nonfullerene acceptors (NFAs) are a new focus in organic photovoltaics (OPVs), and continue to progress upon the drawbacks of many fullerene-based electron acceptors. The aim of this work is to identify some important parameters that influence the efficiency of NF-acceptors in OPVs. These results provide an enhanced understanding of the effect of the NFAs core structure (electron rich/poor group) on the photophysical and optoelectronic properties. In addition, the effect of the small ?LUMO value (the subtle difference in energy between LUMO+1 and LUMO orbitals of NFAs; LUMO=lowest unoccupied molecular orbitals) on ultrafast charge transfer and charge separation processes in OPVs, recently identified as a key factor for all top rated high performing NFAs, is studied. So far, ?LUMO-based theoretical studies are limited to individual NFAs; here, for the first time, the authors have extended to the respective donor/acceptor complexes as well. Finally, based on the first-principles density functional theory calculations with the seven reported NFAs, (Formula presented.), P3HT, and the seven newly modeled donor–acceptor complexes, this study sheds light on important factors that will provide trends and guidelines for further rational design of more efficient NF-acceptors for OPVs.

An efficient palladium-catalyzed denitrogenative Suzuki-Miyaura type cross-coupling of 1,2,3-benzotriazin-4(3H)-ones with organoboronic acid is described. The reaction is compatible with various aryl and alkenyl boronic acids affordingortho-arylated and alkenylated benzamides in good to high yields. Heteroaromatic boronic acids were also successfully employed. Along with this, a coupling reaction was established by using phenyl boronate ester as the coupling partner. The reaction is believed to proceedviaa five-membered aza-palladacyclic intermediate. DFT calculations were studied comparing the reactivity of palladium and nickel complexes in the five-membered aza-metallacycle formation from 1,2,3-benzotriazin-4(3H)-ones. The application of the reaction was successfully demonstrated by convertingortho-alkenylated products toortho-alkylated products in high yieldsviaa reduction reaction.

Particle in a box is a classic example of quantization through confinement. In the literature, many theoretical studies have been reported regarding the application of confinement models with hard and soft boundaries on a wide range of systems with different shapes and sizes. The n-electron delocalization on the surface of fullerene and sphere-like shape of fullerene offers a non-polar spherical confinement. Schlegel and co-workers have also studied the effect of confinement on chemical reactions by considering carbon nanotube (CNT) of different diameter using hybrid density functional theory. Systematic comparison of reaction energies in the gas phase and inside nanotube reveals that the energy barriers inside the tube are higher than the gas phase. The main reason for the high-energy barrier inside nanotube is due to the presence of nanotube confinement.

We systematically designed and developed three novel halogenated aza-octacene derivatives, which have the same ?-conjugated backbone with different terminal halogen groups (F, Cl, Br). These aza-octacene derivatives are synthesized by acid-catalyzed condensation of naphthalene-bisisatin with 4,5-dihalo-1,2-phenylenediamine. The in-depth experimental and theoretical analyses on these molecules, using the non-halogenated system as a reference, allowed us to understand the impact of halogenation on electronic and optical properties. Both electronic affinity (EA) and ionization potential (IP) are increased through peripheral halogen substitution. Chlorination enhances the EA more effectively compared with fluorination and bromination. Micro-crystal devices based on the bromine substituted aza-octacene derivative show only p-type charge transport behavior. In contrast, the chlorinated and the fluorinated aza-octacene derivatives exhibit ambipolar charge transport.

A novel trap mitigation mechanism using molecular additives, which relieves a characteristic early turn-on voltage in a high-mobility p-type acene-based small-molecule organic semiconductor, when processed from hydrous solvents, is reported. The early turn-on voltage is attributed to photo-induced trapping, and additive incorporation is found to be very effective in suppressing this effect. Remarkably, the molecular additive does not disturb the charge transport properties of the small-molecule semiconductor, but rather intercalates in the crystal structure. This novel technique allows for the solution-processing of small molecular semiconductors from hydrous solvents, greatly simplifying manufacturing processes for large-area electronics. Along with various electric and spectroscopic characterization techniques, simulations have given a deeper insight into the trap mitigation effect induced by the additive.

The selection of a suitable density functional theory (DFT) method is critical to study the interfacial interactions between the protonated species and water clusters at the carbon surface. The interfacial interactions are crucial for the stability of complexes with the support of various kinds of noncovalent interactions. To model this environment, we consider excess proton with benzene [i.e., protonated benzene (BZH)] and water clusters using high-level electronic structure calculations. These clusters were stabilized by different kinds of noncovalent interactions at the interface. Modeling these clusters is challenging as high-level electronic structure calculations are expensive, whereas less expensive DFT-based methods are inconsistent. Thus, in the present study, we have chosen various hybrid DFT functionals (such as B3LYP, PBE0, M05-2X, M06-2X, and M11) to study the geometries, energetics, and the importance of interfacial interactions. Furthermore, these methods performance is validated by using MP2/CBS and CCSD(T)/CBS approaches. It is found that the selected functionals are reliable to predict the structure, but the energetics of these clusters are varied. Also, each one of these methods has its own advantage in certain aspects. Scrutiny of result reveals that hybrid GGA (PBE0) and hybridmeta-GGA (M11) functionals are more consistent for the structure and stability with the benchmark obtained from MP2/CBS and CCSD(T)/CBS approaches. Besides, our benchmark report states that the selected DFT method can be suitable for the following individual interactions; (1) PBE0 suited for O–H···O, O–H···? and C–H···O interactions, (2) M05-2X more suited for O–H···?, C–H···O, and (3) B3LYP method highly favor for the O–H···O interactions (i.e., proton transfer). Overall, PBE0/aVTZ method has an excellent correlation with MP2/CBS and CCSD(T)/CBS methods based on our analysis using the mean signed error and correlation coefficient (r) analyses.

We report a novel blue LED mediated intramolecular C-H functionalization of tryptamine derivatives to generate azepino[4, 5-b]indoles (4) in moderate to good yields. By altering the substitution at the tryptamine nitrogen, intramolecular cyclopropanation is achieved in high yields under the same reactions condition to provide natural product inspired polycyclic indoles (6), which are further transformed to spiropiperidino (5 and 8) indoles in decent yields. The mechanism of formation of the compounds was investigated through DFT studies.

The investigation of proton localization at a hydrophobic-hydrophilic interface is an important problem in chemical and materials sciences. In this study, protonated benzene (i.e., benzenium ion) and water clusters [BZHW (where n = 1-6)] are selected as prototype models to understand the interfacial interactions and proton transfer mechanism between a carbonaceous surface and water molecules. The excess protons can localize in the vicinity of the hydrophobic-hydrophilic interface, and these clusters are stabilized by various kinds of noncovalent interactions. Calculations are carried out using ab initio (MP2) and density functional theory B3LYP methods to shed more light on geometries, energetics, and spectral signatures of the protonated species [H(HO)] at the interfaces. These calculations revealed few low-lying isomers, which have not been reported earlier. Scrutiny of the results reveals that proton localization in the hydrophilic environment is more stable than the hydrophobic benzene ?-cloud. Furthermore, the occurrence of an O-H···?hydrogen bond significantly influences the O-H···O interactions in the water clusters and also intensively affects the vibrational modes of the Eigen cation. Thus, the aromatic ?-clouds can stabilize the Eigen cation and at the same time, a twisted form of Eigen (one O-H···?? two O-H···?) can enhance the proton transfer through the water chain via a Grotthuss-type mechanism. The vibrational spectra of these clusters reveal that there is a large red-shifted frequency for the O-H···O, O-H···?, and O-H···?modes of interaction. The energetic values and vibrational frequencies obtained from the B3LYP method are in close agreement with the MP2 level and experimental values, respectively.

We herein describe the design, synthesis, characterization and property evaluation of three novel ?-conjugated ladder-type and asymmetric S,N-heterocyclics with fused six-membered rings. The unique molecular design incorporates electron-deficient pyrazine and electron-donating thienothiophene in one molecular skeleton to achieve fused and asymmetric heterocyclics with six consecutive rings, and we tuned the molecular structure with different alkyl chains and the ending chlorine substitution. Single-crystal structure studies and analysis of opto-electronic properties were carried out to understand the structure-property relationships for applying these ?-scaffolds in organic single-crystal transistors. Charge mobility studies reveal a promising hole mobility of 0.64 cm2 V-1 s-1 for one of the asymmetric S,N-heterocyclics.

We report the "green" synthesis and characterization of a series of fused benzo[1,2-b:4,5-b?]bis[b]benzothiophene (BBBT) polymers containing a phenyl ring and naphthalene as comonomers, as well as BBBT homopolymers. These novel fused polymers have been obtained from simple acid and hexaethyltriaminophosphine catalyzed polymerization without involving any metal catalyst. The effect of the different aromatic units on the optical and electronic properties of the resulting polymers has been studied. It was found that these polymers possess high electron affinities due to the presence of electron-deficient lactams on each repeat unit. BBBT-P and BBBT-N exhibit NIR absorption spectra with the tail extending to 1000 nm, while the BBBT homopolymer exhibits a large blue-shifted absorption.

The first manganese-catalyzed cyclopropanation of indoles is reported in moderate to excellent yield with methyl-2-diazo-2-arylacetates. This new strategy involved acetyl (COCH ) as the directing group and exhibited exceptional functional group tolerance. In the absence of stereodirecting groups the desired products were obtained as a mixture of diastereomers (7:3 ? 8:2). Control experiments and DFT studies elucidated the probable pathway for the formation of cyclopropane-fused indole product. Deacetylation of the final products afforded both C3-substituted NH-indoles.

A new family of azaacenes has been designed and synthesized by incorporating the electron-withdrawing sp-hybridized nitrogen of pyrazine and electron-donating nitrogen of carbazole in a molecular skeleton. Two different conjugated lengths of 8-ring aza-nonacene and 10-ring aza-undecene have been achieved by an efficient condensation reaction. The unique optoelectronic properties of these molecules were investigated using both experimental and theoretical techniques. The azaacenes show visible-region absorption and near-infrared (NIR) fluorescence. These compounds can serve as hole-transport semiconductors for solution-processed organic field-effect transistors (OFETs). Single-crystal transistor devices of one of the aza-nonacenes exhibit hole charge transport behavior with a hole mobility of 0.07 cm/Vs and an on/off current ratio of 1.3x10.

Isobutyraldehyde underwent auto-oxidation in the presence of molecular oxygen to generate an acyloxy radical under a "metal-free" environment. They were subsequently exploited in situ to afford hypervalent iodines with p-anisolyl iodide which generated substituted 1,3,4-oxadiazoles in moderate to excellent yields from N?-arylidene acetohydrazides. The reaction strategy tolerated diverse substitution on the hydrazide substrates. Control experiments and literature precedence supported the formation of an in situ iodosylarene complex that facilitates the formation of products.

Interaction of small neutral coinage metal clusters (M 19 ?=?Ag 19 /Au 19 ) with thiol/alkoxy radical (E?=?-SCH 3, -OCH 3, and -OCH 2 CH 3 ) has been investigated to understand the bonding mechanism in the coinage metal?molecule junctions, which would allow to design biocompatible materials. In this study, structure, reactivity, and energy decomposition analysis (EDA) of M 19 ?E complexes have been unravelled using density functional theory (DFT) based Perdew, Burke and Ernzerhof (PBE) method. In addition, the theory of “atoms in molecules” (AIM) has also been used characterize the nature of interaction. The calculated reactivity descriptors predict that the vertex atoms (Ag/Au) are the most reactive site for nucleophilic attack. The atoms lying at the center of each face are favourable for an electrophilic attack in both the cases. Geometrical parameters illustrate that the structure of the molecules change significantly before and after interactions. The signatures of ? 2 ?( r ) and H c for the anchoring bonds are respectively positive and negative, revealing that these bonds are partially electrostatic and covalent in nature. EDA calculation indicates that the largest contribution to the M?X (X?=?O/S) bond arise from ? E orb and ? E elstat contributions. Specifically, contribution from the orbital interaction is higher than the electrostatic contribution, which further confirms the covalent nature of the interaction.

A novel 6-5-5-5 ring containing mono-ketopyrrole in its fully conjugated state, resembling a ?-expanded diketopyrrolopyrrole analog, has been designed and synthesized. The new type of molecule shows intense visible range absorption and a reversible reduction potential. Further, this class of molecule can be incorporated into a family of alternative conjugated polymers. These new polymers possess planar backbones due to the fused ?-expanded diketopyrrolopyrrole analog building block and smaller steric effects between the thiophene of azaanthracene and the flanking thiophene rings of the comonomer units. These new very low band gap polymers exhibit NIR absorption spectra that are extended to 1200 nm due to the extended effective conjugation length and increased molecular orbital overlap between aromatic monomer units. Our results demonstrate that these ?-expanded diketopyrrolopyrrole analogs could be a useful building block for semiconducting polymers.

We have successfully synthesized four fused hybrid diimide and diamide arrays with different effective conjugation lengths of perylene diimides and isoindigos. These arrays with varying numbers of amides and imides are an efficient strategy to fine-tune the opto-electronic properties, conformation, energy levels and device performance. It is shown that additional fused isoindigos lead to much lower electron affinity with no influence on the ionic potential. The impact of adding different additional central electron deficient isoindigos to the fused arrays has also been investigated systemically. PDI-BDOPV-PDI incorporating a strong electron deficient BDOPV unit with enforced coplanarity exhibits a very low lowest unoccupied molecular orbital (LUMO) level of -4.11 eV, and the absorption spectrum of PDI-DPN-PDI was even extended to 1000 nm. Thin film transistors were fabricated with these arrays as the semiconductor layers, the fused arrays display electron transport behaviors.

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Organic solar cells that use only fullerenes as the photoactive material exhibit poor exciton-to-charge conversion efficiencies, resulting in low internal quantum efficiencies (IQE). However, the IQE can be greatly improved, when copper(I) thiocyanate (CuSCN) is used as a carrier-selective interlayer between the phenyl-C70-butyric acid methyl ester (PCBM) layer and the anode. Efficiencies of ?5.4% have recently been reported for optimized CuSCN:PCBM (1:3)-mesostructured heterojunctions, yet the reasons causing the efficiency boost remain unclear. Here, transient absorption (TA) spectroscopy is used to demonstrate that CuSCN does not only act as a carrier-selective electrode layer, but also facilitates fullerene exciton dissociation and hole transfer at the interface with PCBM. While intrinsic charge generation in neat PCBM films proceeds with low yield, hybrid films exhibit much improved exciton dissociation due to the presence of abundant interfaces. Triplet generation with a rate proportional to the product of singlet and charge concentrations is observed in neat PCBM films, implying a charge–singlet spin exchange mechanism, while in hybrid films, this mechanism is absent and triplet formation is a consequence of nongeminate recombination of free charges. At low carrier concentrations, the fraction of charges outweighs the population of triplets, leading to respectable device efficiencies under one sun illumination.

Highly efficient oxidative annulation of alkynes furnished diversely substituted pyran[2,3,4-de]chromene-2-one derivatives and related polycycles in moderate to high yield. The reaction is catalyzed by nontoxic, air-stable, and inexpensive Cp?Co(CO)I catalyst. The hydroxyl moiety at the substrate acts as the directing group for the C-H bond activation.

A well-defined series of long and soluble isoindigo thienoacene oligomers have been synthesized from a novel electron deficient building block: Benzo[1,2-b:4,5-b?]bis[b]benzothiophene bislactams. Extension of the ?-conjugated systems facilitates control of the optical, electronic and device characteristics.

The structure and stability of various ternary complexes in which an extended aromatic system such as coronene interacts with ions/atoms/molecules on opposite faces of the ?-electron cloud were investigated using ab initio calculations. By characterizing the nature of the intermolecular interactions using an energy decomposition analysis, it was shown that there is an interplay between various types of interactions and that there are co-operativity effects, particularly when different types of interactions coexist in the same system. [Figure : see fulltext.].

The first intermolecular ring-expansion cascade of azirines with alkynes for the synthesis of pyridines, enabled by a copper/triethylamine catalytic system via simultaneous generation and utilization of yne-enamine and skipped-yne-imine intermediates, is reported. Experimental as well as computational mechanistic studies revealed that the role of triethylamine is crucial in deciding the reaction pathway toward the pyridine products. This process offers a novel, one-step, direct, and practical strategy for the rapid construction of highly substituted pyridines under exceedingly mild conditions, and an installed alkyne functionality.