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Cobalt hydroxide Co(OH)2 is considered to be a potential material for electrocatalyst, especially for oxygen evolution reaction (OER), owing to the earth's abundance, environmentally benign nature, and redox-active properties of cobalt. Herein, we report the fabrication of pristine Co(OH)2 and AgNP-integrated Co(OH)2 (Ag–Co(OH)2) by simple wet chemical methods and explore the electrocatalytic OER activity in the alkaline medium. High-resolution transmission electro-microscopic (HR-TEM) analysis revealed featureless nanostructures for Co(OH)2 with coexisting amorphous and crystalline phases, as well as the inclusion of crystalline AgNPs in Ag–Co(OH)2. X-ray photoelectron spectroscopic (XPS) analysis confirmed the inclusion of metallic AgNPs and the presence of Co at a mixed oxidation state. Electrocatalytic OER studies indicated that pristine Co(OH)2 required the overpotential of 299 mV to achieve a geometric current density of 10 mA cm−2. The integration of AgNPs in Co(OH)2 (Ag–Co(OH)2) showed a gradual improvement in the OER activity. The optimized sample, Ag–Co(OH)2-5, required the overpotential of 253 mV to produce 10 mA cm−2 current density. Tafel slope analysis revealed a lower value upon AgNP integration and electrochemical impedance showed lower charge transfer resistance. The lower Tafel value and charge transfer resistance of Ag–Co(OH)2-5 indicated good chemical coupling and faster reaction kinetics at the electrode surface. AgNPs incorporation with Co(OH)2 also showed enhanced turn-over frequency, electrochemical active surface area, and double-layer capacitance. The fabricated hybrid Ag–Co(OH)2-5 catalyst also exhibited good stability over 60 h. Thus, the electrocatalytic activity of low-cost Co(OH)2 was improved by fabricating coexisting amorphous and crystalline phases and integrating noble silver nanoparticles. [ABSTRACT FROM AUTHOR]

The coordination environment and networks of metal–organic frameworks (MOFs) play a significant role in their functional properties, especially catalysis. In recent years, the use of MOFs for electrocatalytic water-splitting reactions to produce green hydrogen fuel has gained increasing attention. Herein, we report the preparation of Co-benzene dicarboxylic acid-based MOFs (Co-MOF-1 and Co-MOF-2) with different coordination environments and correlated their structure-controlled electrocatalytic OER activity in an alkaline medium. Both Co-MOF-1 and Co-MOF-2 showed 3D network structures with different coordination environments around the Co metal centre. In Co-MOF-1, the Co metal centre is coordinated with DMF and pyridine along with a benzene dicarboxylic acid (BDC) ligand, whereas the Co metal centre is coordinated only with BDC ligands in Co-MOF-2. The Co metal centres in Co-MOF-1 contain labile solvent coordination but have completely saturated coordination with the BDC ligand alone in Co-MOF-2. Interestingly, Co-MOF-1 showed relatively strong OER activity and required the overpotential (η) of 294 mV to produce 10 mA cm−2 current density. However, Co-MOF-2 required the overpotential of 343 mV to achieve the 10 mA cm−2 current density. Further Co-MOF-1 showed comparatively low Tafel slope and charge transfer resistance and high electrochemical surface area than Co-MOF-2 and supported the enhanced OER activity. XPS analysis of Co-MOF-1 before and after catalysis suggested the conversion of Co-MOF-1 to CoOOH during the electrocatalysis that boosted the OER activity. The presence of a labile coordination site in Co-MOF-1 might have facilitated the interaction of hydroxyl electrolyte with the metal centre and active site generation by forming CoOOH easily which enhanced the OER activity. Co-MOF-1 also showed excellent stability for over 48 h. Hence, the present work provides structural insight for designing new MOFs for electrocatalytic water-splitting reactions. [ABSTRACT FROM AUTHOR]

The versatility of metal coordination geometry and organic linkers is used to derive metal–organic frameworks (MOFs) with an intriguing network structure in the solid-state, exerting significant control over its functional application. In this study, we prepared Co-benzene dicarboxylic acid based MOFs with 1D and 2D network structures with similar coordination environment and studied their electrocatalytic OER activity in alkaline medium. The use of bidentate amines (2,2′-bipyridine and DABCO) controlled the dimensionality and produced water coordinated 1D (Co-MOF-1D) and 2D (Co-MOF-2D) network structures. Although both Co-MOFs showed strong electrocatalytic OER activity, Co-MOF-2D exhibited relatively strong OER activity (required overpotential (η) of 211 mV to produce 10 mA cm−2 current density) compared to Co-MOF-1D (η10 = 237 mV). Co-MOF-2D exhibited excellent stability with a low Tafel slope, charge transfer resistance, and high electrochemical surface area that further supported the enhanced OER activity. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) with their tunable topology, functionality and coordination environment have been considered as potential materials for various applications including electrocatalysis. Herein, we have synthesised a water coordinated nickel based 2D metal–organic framework (Ni-MOF) and a coordination complex (Ni-C) and investigated their electrocatalytic OER activity. The Ni-MOF showed a 2D sheet structure with one water coordination whereas a four water molecule coordinated charged complex was formed in the Ni-C. Thermogravimetric analysis (TGA) confirmed their water coordination and good thermal stability. Interestingly, electrocatalytic OER studies showed strongly enhanced activity for the Ni-MOF and that it required a low overpotential (194 mV) to produce a geometric current density of 10 mA cm−2. The Ni-C required 225 mV to produce 10 mA cm−2. The post-catalytic analysis suggested that the Ni-MOF and Ni-C are converted to nickel hydroxides/oxyhydroxides during electrocatalysis and acted as the catalytic centre. The low Tafel slope and charge transfer resistance further supported the higher activity of Ni-MOF based nickel hydroxides/oxyhydroxides. Chronoamperometric studies revealed the excellent stability of the Ni-MOF based catalyst over 72 h. The present study revealed the potential of developing highly active electrocatalysts based on Ni-MOFs by optimizing the topology and coordination environment. [ABSTRACT FROM AUTHOR]

Molecular structural tailoring is one of the versatile approaches for developing functional organic fluorescent molecules with desired properties for practical applications. In this manuscript, we report the synthesis of triphenylamine based boron complexes (TPA-BF2) with unusual thermofluorochromism and alkyl chain length controlled molecular fluorescent liquids/solids. TPA-BF2 complexes with ethyl, propyl, butyl and pentyl groups produced fluorescent solids whereas with hexyl, heptyl and octyl groups yielded fluorescent liquids. The longer-alkyl chain compounds significantly improved the fluorescence efficiency (quantum yield (Φf = 12.6%)) by inhibiting close arrangement of fluorophores. TPA-BF2-2 and TPA-BF2-3 showed very weak fluorescence (Φf = 1.9%). On the other hand, all complexes exhibited strong solvent polarity dependent tunable fluorescence in the solution state. Importantly, the ability to form multiple excited states (locally excited (LE), charge transfer (CT) and twisted intramolecular charge transfer (TICT) states) resulted in unusual fluorescence tuning and reversible thermofluorochromism. The conversion of CT emission at RT to LE state emission at 77 K (under liquid nitrogen) of TPA-BF2 complexes in CHCl3/toluene resulted in strong blue shifting, while warming towards RT, the TPA-BF2 CHCl3 solution showed unusual fluorescence tuning. The fluorescence λmax of TPA-BF2-2 was red shifted from 476 to 600 nm and then blue shifted to RT fluorescence (550 nm). Interestingly, TPA-BF2 complexes in solution and in the PMMA matrix showed clear phosphorescence at 77 K. The unusual fluorescence tuning while warming from 77 K is attributed to the phosphorescence emission coupled with fluorescence at room temperature. Notably, the fluorescence intensity at RT was relatively stronger compared to red shifted fluorescence intensity while warming. TPA-BF2 complexes in toluene showed strong linear enhancement of fluorescence intensity (1.9 to 2.5 times) with a blue shifted peak position upon increasing the temperature from 0 to 100 °C. The alkyl chain length exhibited a strong influence on the rate and extent of fluorescence tuning with temperature. Thus, alkyl group variations in simple Schiff base–boron complexes produced unusual thermofluorochromism and molecular fluorescent liquids. [ABSTRACT FROM AUTHOR]

Fluorine and nitrogen codoped cobalt hydroxide–graphene oxide nanocomposites (N,F-Co(OH)2/GO) were synthesized by a simple hydrothermal method and demonstrated highly enhanced oxygen evolution activity in an alkaline medium. N,F-Co(OH)2/GO synthesized under optimized reaction conditions required an overpotential of 228 mV to produce the benchmark current density of 10 mA cm−2 (scan rate 1 mV s−1). In contrast, N,F-Co(OH)2 without GO and Co(OH)2/GO without fluorine required higher overpotentials (370 (N,F-Co(OH)2) and 325 mV (Co(OH)2/GO)) for producing the current density of 10 mA cm−2. The low Tafel slope (52.6 mV dec−1) and charge transfer resistance, and high electrochemical double layer capacitance of N,F-Co(OH)2/GO compared to N,F-Co(OH)2 indicate faster kinetics at the electrode–catalyst interface. The N,F-Co(OH)2/GO catalyst showed good stability over 30 h. High-resolution transmission electron microscope (HR-TEM) images showed good dispersion of polycrystalline Co(OH)2 nanoparticles in the GO matrix. X-ray photoelectron spectroscopic (XPS) analysis revealed the coexistence of Co2+/Co3+ and the doping of nitrogen and fluorine in N,F-Co(OH)2/GO. XPS further revealed the presence of F in its ionic state and being covalently attached to GO. The integration of highly electronegative F with GO stabilizes the Co2+ active centre along with improving the charge transfer and adsorption process that contributes to improved OER. Thus, the present work reports a facile method for preparing F-doped GO–Co(OH)2 electrocatalysts with enhanced OER activity under alkaline conditions. [ABSTRACT FROM AUTHOR]

Well-defined NiSe@ZnSe composite electrode was synthesized along with polyvinyl pyrrolidone (PVP) and sodium lauryl sulfate (SLS) surfactant whose redox behavior is an interesting approach toward boosting performance of the supercapacitor. High crystallinity suggested that prepared composite NiSe@ZnSe was well appropriate for the application concerning the supercapacitor electrode material. The Raman spectroscopy identified the functional group, vibrations, stretching of bonds, and presence of defects in the samples. The surface to volume ratio of the loosely packed grass-like structures resulted in availability of more surface area for the electrolyte which leads to the enhanced reaction rates. As-prepared active synthesized product revealed 442 Fg−1 specific capacitance at 1 Ag−1 with 99.3% high-rate capability at 10 Ag−1 after 2000 cycles. Besides, notably, capacity retention of the sandwiched asymmetric NiSe@ZnSe//AC device was maintained to be 99.48% after constant charge−discharge 2000 cycles and displayed outstanding electrochemical stability. Herein, NiSe@ZnSe composite electrode was prepared because Zn could improve the electrical conductivity and capacitive performance. Ni can improve active site density and conductivity. Meanwhile, selenium enhanced charge transfer properties. Therefore, binary composite NiSe@ZnSe acts as a satisfactory electrode material for energy saving application. [ABSTRACT FROM AUTHOR]

The present investigation highlights the two-dimensional design of several interesting superalkali-doped borophene derivatives for efficient nonlinear optics (NLO). The combination effects and resulting NLO responses of borophene (B36) and superalkali units (Li3O) were evaluated by orienting superalkali clusters at various sites, such as the hub, rim, and bridge, around an B36 molecule. The charge analysis was characterized by frontier and natural bond orbital analyses, a narrowed HOMO–LUMO bandgap and greater intramolecular charge transfers. Molecular electrostatic potential surfaces demonstrated enhanced optoelectronic features of these complexes that are viable due to Li3O adsorption. Singly doped and doubly doped complexes were considered, and their NLO properties were calculated. Bandgap energy was reduced approximately threefold when doped with two Li3O. As a considerably high figure of merit, first hyperpolarizability (βo) values of up to five digits (including 10,611 au for complex A) prove that these systems can be utilized as promising candidates in various NLO applications. [ABSTRACT FROM AUTHOR]

Multifunctional pyrazole derivative, i.e. 3-amino-1-(5-hydroxy-3-methyl-1H-pyrazol-4-yl)-1H-benzo[f]chromene-2-carbonitrile (PBCC) has been synthesized and characterized. To shed light on various properties of interests, the ground state geometry was optimized by adopting Density Functional Theory (PBE/TZ2P). The effect of different functionals on the absorption wavelengths was studied by using Time-Domain DFT (TDDFT), e.g. GGA functional PBE, hybrid functionals B3LYP and PBE0, rang separated functionals CAM-B3LYP, LCY-PBE and CAMY-B3LYP, Dispersion Corrections PBE-D3 and B3LYP-D3. Among all these functionals PBE and PBE-D3 were found to be good choices which reproduced the absorption spectra of the PBCC. With the aim to enhance the electro-optical, charge transfer and photovoltaic properties, five new derivatives were designed by di-substituting the –F, –Cl, –Br, –COOH and –CN at benzochromene moiety. The electron injection barrier, band gap alignment and related calculated photovoltaic parameters revealed that PBCC and its newly designed derivatives would be proficient to be used in photovoltaic devices. These compounds can be used as donor materials in dye-sensitized solar cells (DSSCs) with favorable type-II band alignment. Moreover, PBCC and most of its derivatives might also be good choice as efficient acceptors with poly(dithieno[3,2-b:2,3-d]pyrrole thiophene) (PDTPr-T) and donor materials with Phenyl-C61-butyric acid methyl ester (PC61BM) in organic solar cells. [ABSTRACT FROM AUTHOR]

A novel aggregation induced emission (AIE) active anthracene based dihydroquinazolinone derivative (probe 1) has been synthesized and characterized by means of spectroscopic methods. The photophysical properties of this probe have been investigated in solvents of different polarity display that fluorescence states are of intramolecular charge transfer (ICT) character. Probe 1 show clear AIE behavior in water/THF mixture on reaching water fraction 95%. The AIE behavior of probe 1 have been exploited for the detection of metal ions in aqueous solution which reveals high selectivity and sensitivity towards Cu2+ ions by colorimetrically and function as a chemosensor in a remarkable turn-off fluorescence manner. Further, the experimental results were investigated by computational means by optimizing the ground state geometries of probe 1 and probe 1-Cu complex using density functional theory (DFT) at B3LYP/6-31G** and B3LYP/6-31G**(LANL2DZ) levels of theory. Intra-molecular charge transfer was observed in probe 1 while ligand to metal charge transfer (LMCT) for probe 1-Cu complex. [ABSTRACT FROM AUTHOR]

Two new anthracene derivatives donor–π–acceptor (Compound 1 ) and acceptor–π–acceptor (Compound 2 ) have been designed with the aim to understand the effect of donor and acceptor on the electronic, optical and charge transfer properties of sensitizers and sensitizers@TiO 2 cluster. The electron donating group (–OH) and acceptor (–COOH) have been substituted at periphery and the effect was studied thoroughly. The ground state geometries of both the compounds were optimized by using density functional theory (DFT) at B3LYP/6-31G**, CAM-B3LYP/6-31G** LC-BLYP/6-31G**, BHandHLYP/6-31G** and PBE1PBE/6-31G** levels of theory. Moreover, ground state geometries of sensitizers@TiO 2 cluster were optimized by adopting the same methods along with LANL2DZ pseudopotential for Ti while 6-31G** basis set for all other atoms. The electro-optical properties and charge transfer nature of dye adsorbed at TiO 2 cluster were also systematically investigated. The absorption spectra of anthracene derivatives before and after adsorption at TiO 2 cluster were limelighted by adopting time dependent DFT. [ABSTRACT FROM AUTHOR]

Pyrazole compounds are gaining noteworthy attention in our daily life from better biological active to the semiconducting materials. Present work deals in depth study of indigenously synthesized pyrazole compound, i.e., 2-[(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)methylidene]indan-1,3-dione ( DMPI ) with respect to the structural, electronic, optical and charge transport properties. The ground and excited state geometries were optimized by applying density functional theory (DFT) and time dependent DFT, respectively. The frontier molecular orbitals (FMOs) have been spotlighted. The comprehensible intra-molecular charge transfer (ICT) from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) was observed. The absorption and emission wavelengths were studied at the TD-B3LYP/6-31G** level of theory. The total and partial density of states (T/PDOS) has been studied to understanding the contribution of different states in the electronic properties. The ionization potentials (IP), electron affinities (EA), reorganization energies, transfer integrals, intrinsic mobility and structure-property relationship have been discussed intensively. The smaller hole reorganization energy and superior transfer integral values resulting improved hole intrinsic mobility than the electron ones is revealing that DMPI would be better hole transport material. [ABSTRACT FROM AUTHOR]

The quinazolinone compounds (1 and 2) in this work were examined for their in vitro antibacterial activities against gram-positive (Staphylococcus aureus) and gram-negative bacteria (Klebsiella pneumonia, Proteus bacilli and Shigella flexneri). Compared to the reference antibiotic chloramphenicol, these compounds showed high antibacterial activities against studied strains with inhibition zones observation. The ground state geometries have been optimized by using density functional theory (DFT) at B3LYP/6-31G* level of theory. The absorption spectra have been calculated by using time dependent density functional theory (TDDFT) with and without solvent. The effect of different functionals (B3LYP, MPW1PW91, and PBE1PBE) on the absorption wavelengths has been studied. The ionization potential (IP), electron affinity (EA), energy gap (Egap), electronegativity (χ), hardness (η), electrophilicity (ε), softness (S) and electrophilicity index (εi) were computed and discussed. The nonlinear optical (NLO) properties vary by changing the theory (DFT to HF) or functional (B3LYP to CAM-B3LYP). The physicochemical parameters have been studied by quantitative structure-activity relationship (QSAR). The computed properties of investigated compounds have been compared with the Chloramphenicol as well as available experimental data. [ABSTRACT FROM AUTHOR]

This study spotlights the fundamental insights about the structure and static first hyperpolarizability ( β) of a series of 2,4-dinitrophenol derivatives (1-5), which are designed by novel bridging core modifications. The central bridging core modifications show noteworthy effects to modulate the optical and nonlinear optical properties in these derivatives. The derivative systems show significantly large amplitudes of first hyperpolarizability as compared to parent system 1, which are 4, 46, 66, and 90% larger for systems 2, 3, 4, and 5, respectively, at Moller-Plesset (MP2)/6-31G* level of theory. The static first hyperpolarizability and frequency dependent coupled-perturbed Kohn-Sham first hyperpolarizability are calculated by means of MP2 and density functional theory methods and compared with respective experimental values wherever possible. Using two-level model with full-set of parameters dependence of transition energy (Δ Ε), transition dipole moment ( μ0) as well as change in dipole moment from ground to excited state (Δ μ), the origin of increase in β amplitudes is traced from the change in dipole moment from ground to excited state. The causes of change in dipole moments are further discovered through sum of Mulliken atomic charges and intermolecular charge transfer spotted in frontier molecular orbitals analysis. Additionally, analysis of conformational isomers and UV-Visible spectra has been also performed for all designed derivatives. Thus, our present investigation provides novel and explanatory insights on the chemical nature and origin of intrinsic nonlinear optical (NLO) properties of 2,4-dinitrophenol derivatives. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Highlights: [•] DFT and TDDFT have been applied to investigate the properties of interests. [•] Intra-molecular charge transfer was observed from donor to acceptor moieties. [•] The designed materials would be good contenders for photovoltaic technology. [ABSTRACT FROM AUTHOR]

Highlights: [•] ICT has been improved by introducing the bridge, donor and acceptor moieties. [•] Electronic, optical and charge transport properties have been tuned. [•] DFT and TDDFT have been applied to predict the properties. [•] The IP, EA, reorganization energies and FMOs have been discussed thoroughly. [Copyright &y& Elsevier]

Highlights: [•] Ground state structures have been optimized by using density functional theory. [•] Substitution of boron, fluoro and nitrogen would improve the electron transport. [•] The boron analogues would be better n-type materials having higher EAs. [•] Charge transfer behavior has been discussed by IP, EA and reorganization energies. [•] The crystal structure of parent molecule has been successfully regenerated by MM. [ABSTRACT FROM AUTHOR]

Highlights: [•] New multifunctional materials have been modeled. [•] Effect of EDGs and EWGs was investigated on charge transfer and optical properties. [•] The intra-molecular charge transfer was observed from donor to acceptor moieties. [•] By DFT and TDDFT, different properties were computed. [•] The modeled compounds would be efficient semiconductor materials for multipurpose. [Copyright &y& Elsevier]

Highlights: [•] Pyrazole-carboxamides have been synthesized and characterized. [•] DFT and TDDFT were applied to study the optical and charge transfer properties. [•] The π-conjugation lowers the energy level of the frontier molecular orbitals. [•] The lowered LUMO energy level would be beneficent for the flow of electrons. [•] The electron injection, LHE and electronic coupling constant have been computed. [Copyright &y& Elsevier]

The structures of 5,5′-bis(naphth-2-yl)- 2,2′-bithiophene (NaT2), 5,5″-bis(naphth-2-yl)-2,2′:5′,2′-terthiophene (NaT3), 5,5‴-bis(naphth-2-yl)-2,2′:5′,2″:5″,2‴-tetrathiophene (NaT4), 5,5″″-bis(naphth-2-yl)-2,2′:5′,2″:5″,2‴:5‴,2″″-quinquethiophene (NaT5) and 5,5′″″-bis(naphth-2-yl)-2,2′:5′,2″:5″,2‴:5‴,2″″:5″″,2′″″-sexithiophene (NaT6) have been optimized at PBE1PBE/6-31G* level of theory. By increasing the chain length (thiophene units) energy gap decreases. The hole reorganization energy also decreases from NaT2-NaT6. We have observed that mobility of NaT5 and NaT6 can be enhanced by minimizing the polarization and relaxation. The end-capped naphthyl groups have been rotated from 0°-60° in the case study of NaT2, it was found that hole reorganization energy increases with the increment in angle. Furthermore the charge transport properties of 5,5′-bis(thionaphth-2-yl)-2,2′-bithiophene (TNT2), 5,5″-bis(thionaphth-2-yl)-2,2′:5′,2″-terthiophene (TNT3), and 5,5‴-bis(thionaphth-2-yl)-2,2′:5′,2″:5″,2‴-quaterthiophene (TNT4) have been investigated at the same level of theory. It has been studied that cis isomers have higher hole reorganization energies as compared to trans ones thus these isomers would diminish the mobility. [ABSTRACT FROM AUTHOR]

The escalating need for energy in the context of future development has prompted a significant surge in research efforts focused on exploring renewable energy sources. The utilization of transition metal oxides in conjunction with reduced graphene oxide (rGO) as economically viable electrocatalytic materials for the oxygen evaluation reaction (OER). This study showcases a straightforward hydrothermal technique to produce perovskite-type ZnMnO 3 nanoparticles that interact with reduced graphene oxide (rGO) to examine electrocatalytic efficiency of ZnMnO 3 /rGO catalyst, particularly in relation to OER. However, electrochemical results of the ZnMnO 3 /rGO catalyst exhibited outstanding electrocatalytic performances with significant overpotential (η) of 253 mV at 10 mA cm−2. Additionally, it exhibited Tafel slope of 38 mV dec−1, indicating efficient catalytic activity. Furthermore, the synthesized catalyst demonstrated a significantly low impedance (R ct) of 1.91 Ω with higher stability after the 5000th cycle. The catalytic electrode shows excellent long-term stability for OER, making it a promising alternative to electrocatalysts for new-generation applications. [Display omitted] • Fabrication of ZnMnO 3 /rGO catalyst was involved for enhanced OER activity. • ZnMnO 3 /rGO catalyst shows a reduced overpotential (253 mV). • ZnMnO 3 /rGO demonstrates cycling stability of 30 h even after 5000th cycle. • ZnMnO 3 /rGO catalyst reveals reduced charge transfer resistance (R ct) of 0.65 Ω. [ABSTRACT FROM AUTHOR]

Significant research is currently performed on electrochemical water splitting to solve ecological problems and energy issues. Sustainable and eco-friendly energy systems prefer to generate cost-effective electrocatalyst material with higher stability and excellent electrocatalytic activity to speed up the oxygen evolution reaction (OER) process. The current study followed a hydrothermal approach to develop a barium cerium oxide nanohybrid with g-CN (BaCeO 3 /g-CN) as an electro-catalyst for an efficient OER process in 1.0 M KOH. Physical characteristics analyses confirmed the enhanced activity of the synthesized BaCeO 3 (BCO) and BCO/g-CN nanohybrid materials. The evaluated increased performance may be ascribed to improved morphological characteristics and substantial surface area (212 m2 g−1). The nanocomposite as mentioned above (BCO/g-CN) exhibits significant potential for effective OER in electrochemical assessments due to its abundant active spots and accelerated charge transfer process. Further, the electro-catalytic activity of the composite is improved, as demonstrated by a reduced overpotential (η = 210 mV) with Tafel value (36 mV dec−1) in comparison to pristine BCO (η = 262 mV and 52 mV dec−1) for OER. The material exhibited a reduced charge transfer impedance (R ct = 0.7 Ω), confirmed by EIS analysis. It also demonstrated a substantial ECSA (electrochemical active surface area) of 237.5 cm2 as compared to the pure BCO (137.5 cm2) material. Moreover, electrocatalyst material durability for 30 h was assessed by a chronoamperometric study. Thus, BCO/g-CN exhibits a notable rise in electrochemical properties, suggesting that it is a viable candidate for prospective OER applications. [Display omitted] • BaCeO 3 /g-CN nanomaterial was synthesized by simple hydrothermal technique. • The conductivity of nanohybrid BaCeO 3 was analyzed under 1.0 M KOH for OER. • BaCeO 3 /g-CN material had higher surface area (70.6 m2 g−1) than pure BaCeO 3. • The cyclic stability of BaCeO 3 /g-CN is remarkable after 5000 cycles. [ABSTRACT FROM AUTHOR]

The possible eight rotamers of 3′-Methyl-quercetin have been optimized by using density functional theory (DFT) at B3LYP/6-31G ∗ level of theory. The molecular structure and molecular properties of the most stable rotamers have been investigated at the same level of theory. We have computed the descriptors; electronegativity ( χ ), hardness ( η ), electrophilicity (ω), softness (S) and electrophilicity index (ωi) by DFT approach. We have shed light on the structure–property relationship. The absorption spectrum has been computed by time dependent density functional theory (TD-DFT) at TD-B3LYP/6-31G ∗ level of theory. Radical scavenging activity has been explained on the basis of bond dissociation enthalpy (BDE) and the adiabatic ionization potential (IP). Two mechanisms have been explained for the radical scavenging processes, i.e., hydrogen atom transfer and one-electron transfer. [ABSTRACT FROM AUTHOR]

Due to the unique structures of helicenes, we aim to probe their prospective as proficient optoelectronic and charge transfer materials. With the intention to shed light on both at the molecular and bulk levels various properties of interest have been studied. The optical (refractive indices, reflectivity, conductivity, absorption, dielectric constant and extinction coefficient) and electronic properties (total/partial density of states (T/PDOS) of some recently synthesized diquaternary salts of 4,4′-bipyridine helical viologens, i.e., 5,10-dimethyl-5,10-diaza[5]helicene bis-tetrafluoroborate 1 2+ (Compound 1 ) and 3,8-dimethyl-3,8-diaza[5]helicene bis-tetrafluoroborate 2 2+ (Compound 2 ) at the bulk level in solid-state have been reflected. The balanced values of hole and electron electronic coupling ( V h and V e ) for compound 1 disclose that it might be good ambipolar material. For Compound 2 V e is greater than V h enlightening that it might be good electron transfer contender. Furthermore, the electronic, photophysical (absorption, fluorescence, phosphorescence) and charge transfer properties (ionization potential (IP), electron affinity (EA) and hole/electron reorganization energy (λ(h)/(e)) of their bipyridine precursors (Compound 3 and Compound 4 ) as well as redox partners of Compound 1 and Compound 2 which are neutral forms of 1 2+ and 2 2+ named Compound 5 and Compound 6 , respectively have been explored. The band gap, DOS, dielectric function, conductivity and refractive indices, IP, EA and λ(h)/(e) values revealed that these diaza[5]helicenes would be good contenders to be used in semiconductor devices. The dielectric functions also revealed that Compounds 1 and 2 retain energy holding ability which these systems absorb. It is also expected that absorption capability of photons would be enhanced in studied compounds especially Compounds 5 and 6 having narrow band gaps. [ABSTRACT FROM AUTHOR]

This study reports the fabrication of CuBi 2 O 4 (CBO) and rGO/CBO nanocomposite by hydrothermal approach. rGO/CBO nanocomposite morphological and structural properties were confirmed via various techniques. rGO/CBO nanocomposite demonstrated capacitance of 1426 F/g and a power density (P d) of 225 W/kg @ 1 A/g through electrochemical studies. rGO/CBO demonstrated a charge transfer resistance of 1.76 Ω smaller than CBO (2.62 Ω) determined through the Nyquist plot. rGO addition to CBO, quicker charge ion transportation enhanced conductivity and increase in capacitance. rGO/CBO nanocomposite exhibited excellent stability over the 5000th cycle. Therefore, rGO/CBO nanocomposite is a viable option to be employed as supercapacitor electrode material and is also utilized in various energy storage devices. • rGO/CuBi 2 O 4 nanocomposite was fabricated by hydrothermal method for supercapacitor applications. • rGO increased CuBi 2 O 4 conductivity by increasing its interfacial area. • rGO/CuBi 2 O 4 nanocomposite demonstrate high specific capacitance and power density of 1426 F/g and 225 W/kg, respectively. • Electrochemical results showed increased conductivity, charge transfer resistance and active sites. [ABSTRACT FROM AUTHOR]

This work presents the fabrication of a novel CeVS 3 /rGO nanocomposite using an easy hydrothermal route for supercapacitor applications. Physical studies revealed that CeVS 3 showed flakes-like morphology, which is successfully decorated on reduced graphene oxide (rGO) sheets in nanocomposite. The electrochemical studies exhibited that fabricated CeVS 3 /rGO showed improved capacitive behavior with notable specific capacitance (C s) of 1516 F/g at 1 A/g current density (j d) as well as excellent rate capability due to combined effect of CeVS 3 nanoflakes and rGO sheets. Nanocomposite also demonstrated a lower resistance of 0.21 Ω than pure material, which have a charge transfer resistance (R ct) of 0.48 Ω. Furthermore, a two-electrode symmetric study was carried out in KOH solution (2.0 M), demonstrating a specific energy (S E) of 18.73 Wh/kg and specific power (S P) of 264.5 W/kg with remarkable cyclic stability after 5000 cycles. These findings demonstrated that innovative CeVS 3 /rGO can be utilized in next-generation supercapacitor applications. [Display omitted] [ABSTRACT FROM AUTHOR]

• Optoelectronic properties of DPPQ derivatives are analysed at molecular and bulk scales. • Effect of various electron donating amines was explored on various properties of interests. • Green, yellow, orange and red light emitters were explored. • The p -type or balanced charge transport nature of compounds has been explored. • DOS, dielectric constant, conductivity function and intrinsic mobility displayed them as multifunctional materials. Effect of various electron donating amines, i.e. , dimethylamine (DMA), diphenylamine (DPA), phenylnaphthylamine (PNA) and dinaphthylamine (DPA) at 6 position on the electronic, photophysical and charge transfer properties of 1,3-diphenyl-1H-pyrazolo[3,4- b quinolone (DPPQ) as a parent molecule has been explored at the molecular and solid state bulk level. The effect of substituents on absorption and emission was studied at TD-B3LYP/6-31G** level in acetonitrile. The computed emission wavelengths were being red shifted for DMA-DPPQ , DPA-DPPQ , PNA-DPPQ than that of parent molecule which might be green, yellow, orange and red light emitters. The charge transfer nature of various DPPQ derivatives has been explored on the bases of ionization potential, hole extraction potential, electron affinity, reorganization energies, transfer integrals and intrinsic mobility. The DMA substitution at position 6 of DPPQ boost up the electron transfer integrals leading to balanced charge transport for holes and electrons. Moreover, total/partial density of states and optical properties (dielectric constant, extinction coefficient refractive indices, reflectivity and conductivity) at solid state bulk scale have been explored. Different properties of interest at molecular and solid state levels revealed that 1,3-diphenyl-1H-pyrazolo[3,4-b]quinolone derivatives would be efficient materials to be used in multifunctional organic semiconductor devices. [ABSTRACT FROM AUTHOR]

• Quantum chemical calculations on performed on few oxazole compounds using. • Band gap, local softness values have been procured for different solvents. • Chemical structure and reactivity, topological analyses were carried out. • Solvation effects on UV–Visible spectrum were inspected using the TD-DFT system. • Optical properties and charge transport nature of the compounds were explored. The ground state geometries of oxazole compounds, i.e. , 3,5-Bis-(4-chloro-phenyl)-7a-methyl-dihydro-oxazolo[3,4-c]oxazole (Compound 1) and 3,5-Bis-(4-methoxy-phenyl)-7a-methyl-dihydro-oxazolo[3,4-c]oxazole (Compound 2) were optimized using Density functional theory employing B3LYP/6-31G++ level for comparing the geometric parameters (torsion angles, bond angles & bond lengths) with the X-ray crystallographic information. We explored the charge transport nature, wave functional properties, optical and electronic properties of both the oxazoles. The computed geometric parameters are rational to the experimental data. The time-domain TD - B3LYP/6-31G++ & the B3LYP/6-31G++ levels were used to reveal the electronic characteristics and absorption wavelength. Intra-molecular charge transfer was perceived in studied compounds. The IEFPCM (Integral Equation Formalism Polarizable Continuum Model) model was used to calculate the solvation UV spectrum. The effect of various solvents (acetone, acetonitrile, DMF(Dimethylformamide), DMSO (Dimethyl sulfoxide) and methanol) was examined on the excitation energies but solvent polarity has no discernible impact on the wavelengths of absorption. From HOMO-LUMO (Highest Occupied Molecular Orbital – Lowest Unoccupied Molecular Orbital) orbitals with various solvent molecules, band gap energies with the solvation effect are determined. Additionally, through the use of topological analytics like RDG (Reduced Density Gradient), ELF (Electron Localisation Function) & LOL (Localised Orbital Locator), the energy concentration of electrons was elucidated. Furthermore, the outcome of electron-donating cluster (–OCH 3) and electron-withdrawing cluster (–Cl) was studied on open-circuit voltage, bandgap alignment, electron coupling constants, excitons dissociation values, ΔGinject – electron injection, LHE-Light Harvesting Efficiency and electron coupling constants (|V RP |). [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract The graphene nanoribbons (GNRs) have been established for device applications in numerous fields due to their superb electro-optical properties. GNRs are used in many nanoscale electronic devices, e.g., solar cells, semiconductors, field effect transistors and nonlinear optics. The isolated molecule precursor of boron doped GNR parent compound 5,10-bis(10-bromoanthracene-9-yl)-5,10-dihydroboranthrene (Br-GNR) and its newly designed derivatives 5,10-bis(10-fluoroanthracene-9-yl)-5,10dihydroboranthrene (F-GNR) and 5,10-bis(10-chloroanthracene-9-yl)-5,10dihydroboranthrene (Cl-GNR) were optimized using density functional theory (DFT) at PBE0/6-311G* level. By replacing the –Br by –F atoms in Br-GNR, the ionization potential (IP) and electron affinity (EA) declined. The hole and electron reorganization energies (λ(h)/λ(e)) of halogenated doped GNRs has been systematically compared with some standard hole and electron transfer materials. The smaller λ(h) values are showing that the studied compounds would be superior hole transfer candidates. The density of states and optical properties at bulk level (including dielectric function, refractive indices, conductivity and loss function) have been probed. The polarizability (γ) amplitudes of F-GNR, Cl-GNR and Br-GNR are 34, 21 and 22 times larger than that of para -nitroaniline at same PBE0/6-311G* level. The calculated non-linear optical (NLO) polarizability amplitudes, optoelectronic and charge transfer properties showed that all the compounds would be good contenders for NLO and semiconductor devices. [ABSTRACT FROM AUTHOR]

With the aim to tune the optoelectronic, charge transport and nonlinear optical properties, four novel star shaped compounds were designed from the initial structure 4,6-di(anthracenothiophen-2-yl)pyrimidine (DATP). The (2,5-di-(thiophen-2-yl)-4,6-di-(anthracenothiophen-2-yl)pyrimidine) ( 1 ), (2,5-di(benzo-thiophen-2-yl)-4,6-di-(anthracenothiophen-2-yl)pyrimidine) ( 2 ), 2,5-di(naphthothiophen-2-yl)-4,6-di-(anthracene-thiophen-2-yl)-pyrimidine ( 3 ), and 2,4,5,6-tetrakis(anthracene-thiophen-2-yl)pyrimidine ( 4 ) were deliberated by substituting the thiophene, benzothiophene, naphthothiophene and anthracenothiophene moieties at positions 2 and 5 of the pyrimidine unit in DATP, respectively. The ground and excited state geometries were optimized by adopting the density functional theory (DFT) and time-dependent DFT at B3LYP/6-31G** and TD-B3LYP/6-31G** level of theories, respectively. We shed light on the energies of the frontier molecular orbitals (FMOs), energy gaps (E gaps ), absorption, fluorescence, total/partial density of states (T/PDOS), molecular electrostatic potentials (MEP) and non-linear optical (NLO) properties. The comprehensible intra-molecular charge transport has been noticed from side wings to the electron-deficient central core at both the ground and excited states. The increment in the wings length increases the electron affinity, reduces the ionization potential and lowered the hole reorganization energy. The higher electron affinity and smaller hole reorganization energy values revealed that newly designed materials might be thermodynamically more stable with enhanced intrinsic hole mobility. [ABSTRACT FROM AUTHOR]

The naphthalene is good contender which is intensively used in organic semiconductors. Here, three new naphthalene based compounds were prepared by the condensation of 1,5-diaminonaphthalene, 5-methylfurfural and 5-nitrofurfural. The prepared Schiff base compounds were analyzed by Fourier Transmission Infrared spectroscopy (FTIR), UV–vis spectroscopy (UV-vis) and single crystal x-ray studies. The compound 1 was obtained in P21/n crystal packing. A comprehensive electronic structure-property relationship was elucidated through the prism of frontier molecular orbitals (FMOs). The calculated absorption wavelengths at TD-B3LYP/6-31G** level displayed reasonably decent agreement to the experimental data. The effect of electron donating groups and electron withdrawing groups was discussed on optoelectronic properties, ionization potentials, electron affinities and reorganization energies. On the basis of transfer integrals and intrinsic mobility nature of the charge transport of compound 1 was discussed. The electron injection, electronic coupling constant and light harvesting efficiency revealed that the studied Schiff base compounds would be good contestants to be used in dye-sensitized solar cells. Compounds 2 and 3 have 8 and 6 times larger β tot than that of para-nitro aniline revealing that these materials might be good for nonlinear optics as well. [ABSTRACT FROM AUTHOR]

Borophene-based mixed-dimensional van der Waals heterojunction is prepared and utilized for self-powered photoelectrochemical (PEC)-type photodetector. [Display omitted] • Mixed-dimensional van der Waals 2D B@ 0D Bi heterojunction is designed. • B@Bi-based PEC-type photodetector exhibits self-powered photodetection capability. • The photodetector exhibits fast response and recovery speed. The ongoing pursuit of mixed-dimensional van der Waals heterojunctions has attracted enormous interests owing to their obviously enhanced photoelectrochemical (PEC) characteristics compared to their single components. Herein, we demonstrate the preparation of 0D Bismuth nanoparticles (Bi NPs) coated 2D Borophene (B@Bi) mixed-dimensional heterojunction by hydrothermal method. Benefiting from the promoted photo-induced electron/hole pair separation, shorted charge transfer length, and built-in electric field, the fabricated B@Bi-based PEC-type photodetector (PD) exhibits enhanced self-powered photodetection properties along with the fast response and recovery speed (0.02/0.02 s) in 0.5 M KOH electrolyte under 365 nm illumination. Additionally, repeatable ON/OFF switch signals can be observed after 30 days. Our present work provides an opportunity for fabricating high-performance mixed-dimensional B@Bi-based PDs with good long-term stability. [ABSTRACT FROM AUTHOR]

A comprehensive investigation on the photophysics of a π -conjugated potential push–pull chromophore system 4,4′-(1E,1′E)-2,2′-(Pyrazine-2,5-diyl)bis(ethene-2,1-diyl)bis(N,N-dimethylaniline) (PENDA) has been carried out spectroscopically. The optical absorption and emission properties of this molecule have been studied in different solvents. The molecule PENDA shows strong solvatochromic emission upon changing the solvent polarity from nonpolar to polar; indicating that emission state is of intramolecular charge transfer (ICT) character. The solvent effect on the spectral properties such as singlet absorption, molar absorptivity, oscillator strength, dipole moment and fluorescence quantum yield of PENDA have been studied in detail. Lippert–Mataga and Reichardt correlations were used to estimate the difference between the excited and ground state dipole moments (Δ μ ). Ground and electronic excited states geometric optimizations were performed using density functional theory (DFT) and time-dependent density functional theory (TDDFT), respectively, with the Gaussian 09 package. A solution of (8 × 10 −5 M) PENDA in THF, dioxane, CH 3 CN and CHCl 3 gives laser emission when pumped by a nitrogen laser pulse ( λ ex = 337.1 nm) of 800 ps duration and 1.48 mJ pulse energy. PENDA dye displays fluorescence quenching by colloidal silver nanoparticles (Ag NPs) in ethanol. The fluorescence data reveal that dynamic quenching and energy transfer play a major role in the fluorescence quenching mechanism. [ABSTRACT FROM AUTHOR]

[Display omitted] • Symmetrical disubstituted compounds with D-A-D-A-D configuration was synthesized. • Exhibited excellent NLO properties with promising optical limiting threshold values under nanosecond pulse excitation. • A detailed energy level mechanism is proposed for the NLO activity of the molecules. • Formation of charge separation state by photo-induced charge transfer is discussed. Organic materials figure among the most widely investigated nonlinear optical (NLO) materials towards the realization of optical limiters. Among the organic materials, donor–acceptor systems are getting special consideration due to their excellent NLO activities arising from the intramolecular charge transfer (ICT). But NLO activities of many of these systems are restricted by photo-bleaching and limited thermal stability. This deficiency can be overcome by introducing more than one donor–acceptor groups into the framework. Herein we report NLO activities of two symmetrical disubstituted compounds with D-A-D-A-D configuration, containing bis-1,3,4-oxadiazole with phenothiazine backbone in which two different electron donor systems namely naphthalene (NOPON)/4-bromophenyl (BOPOB) were bonded with the phenothiazine-1,3,4-oxadiazole core unit. Solution phase absorption spectrum of these compounds exhibited two peaks, one located in the 300–350 nm regions and a comparatively weak and broad band located at the longer wavelength region attributed to ICT state. Photophysical, electrochemical and excited state life time analysis of the compounds were carried out. HOMO-LUMO energies of the system obtained from DFT calculation are comparable with the experimental values obtained from voltammetric study. NLO and optical limiting behaviour of the compounds were analysed by Z scan technique using a Q switched Nd: YAG laser at 532 nm. Both the compounds exhibited promising limiting threshold values (2.43 J/cm2 for NOPON and 3.80 J/cm2 for BOPOB) comparable with many of the reported values, suggesting their ability to perform as good optical limiters. [ABSTRACT FROM AUTHOR]

Abstract: In this study initial molecular structures of benzene, pyrazine, pyridazine, pyridine, pyrimidine, cyclopentadiene, furan, pyrrole and thiophene have been optimized at the ground (S0) and excited (S1) states using density functional theory (DFT) and time-dependent density functional theory (TD-DFT), respectively. We also evaluate the distribution patterns of HOMOs (highest occupied molecular orbitals) and LUMOs (lowest unoccupied molecular orbitals) for these molecules at the ground (S0) and excited (S1) states. The photophysical properties, i.e., absorption (λ a), and emission (λ e), have been computed by TD-DFT. The calculations regarding to reorganization energies, vertical electron affinity (EAv), adiabatic electron affinity (EAa), vertical ionization potential (IPv) and adiabatic ionization potential (IPa) of the investigated molecules have been performed by applying DFT to shed light on the charge transfer properties. The effect of heteroatoms substitution on the geometrical parameters, electronic, optical and charge transfer properties has also been investigated. It was observed that benzene, furan, pyrazine, pyridazine, pyridine and pyrimidine have higher IPa compared to that of cyclopentadiene, pyrrole and thiophene. Pyridazine, pyrazine, pyridine and pyrimidine have higher EAa than that of cyclopentadiene, pyrrole and thiophene. The benzene and cyclopentadiene have low hole reorganization energies λ(h) compared to their electron reorganization energies λ(e), so they might be used as good hole transport co-monomers. The molecules of pyrazine, pyridazine, pyridine, pyrimidine, furan, pyrrole and thiophene have the electron reorganization energies λ(e) smaller than their hole reorganization energies λ(h) revealing these would be better to design electron transport materials. [Copyright &y& Elsevier]