HOMO-LUMO Energy Levels Research Articles

Synthesis, crystal structure characterization, DFT calculations, Hirshfeld surface analysis and 3D energy frameworks of triazole pyridazine derivatives: Theoretical and experimental studies

Recently, pyridazine derivatives have shown considerable biological properties such as anti-tumor and anti-inflammatory activity. The studied compounds 6-chloro-3-[(4-methylphenoxy)methyl][1,2,4] triazolo[4,3-b]pyridazine (8a) and 6-chloro-3-[(4-fluorophenoxy)methyl][1,2,4] triazolo[4,3-b]pyridazine (8b) have been synthesized and characterized by NMR, IR and mass spectral studies, and finally, the structures were confirmed by single crystal X-ray diffraction technique. The compounds 8a and 8b have crystallized in the same crystal system with different space groups. Density functional theory calculations were performed to compare the theoretical and experimental results obtained from XRD. Further, DFT calculations were employed to determine HOMO-LUMO energy levels, energy gap, softness, hardness, and other quantum chemical parameters of the compounds 8a and 8b. Hirshfeld surface analysis was carried out to distinguish the different intermolecular hydrogen bonds. Energy frameworks for the compounds were constructed through different intermolecular interaction energies to know the dominant interaction energy involved in the molecular packing strength.

Dramatically Enhanced and Red-shifted Photoluminescence Achieved by Introducing an Electron-withdrawing Group into a Non-traditional Luminescent Small Organic Compound.

Small organic compounds without any traditional fluorescent chromophores are generally non-emissive, and only very few are reported to emit weak blue fluorescence. Here we synthesized a non-traditional luminescent small organic compound N-(2,2,2-trifluoroethyl)acrylamide (TFAM) with dramatically enhanced and red-shifted photoluminescence by introducing a strong electron-withdrawing group into acrylamide (AM). Very impressively, TFAM emits cyan (472 nm) and yellow-green (560 nm) fluorescence in solutions and solid state, respectively. TFAM also shows aggregation-induced emission enhancement (AIEE) and excitation-dependent fluorescence (EDF) characteristics, as well as temperature and metal cations-responsive fluorescence. Theoretical calculations show that the introduction of electron-withdrawing group leads to a lower energy gap between the HOMO-LUMO energy levels in TFAM than in AM. And strong cooperative hydrogen bonds are formed in TFAM molecules, resulting in rigidification of molecular conformations. The study provides a strategy for preparing non-traditional luminescent compounds with enhanced and red-shifted photoluminescence.

DFT/TD-DFT Study of Donorπ-Acceptor Organic Dye models contained Triarylamine for an Efficient Dye-Sensitized Solar Cell

A systematic theoretical study was performed for dipolar triarylamine-based Dπ-A dyes. These dyes are composed of good required features to be active for enhancing the efficiency of solar cell such as arylamine donor moieties, and an acceptor part with cyanoacetic acid, while the conjugation process is adopted by the fluorene or biphenyl linkers. The required properties both electronic and opticals were computed with DFT/TDDFT levels and 6-31G (d, p) basis set, then show the response of the efficiency. The obtained results have predicted the excitation energies, HOMO-LUMO energy levels which indicate an improvement in the two principle processes; electron injection and the regeneration of dyes. Also, the important factors in close connection with the short-circuit current density (Jsc), such as light-harvesting efficiency (LHE), the open-circuit photovoltage (Voc), total reorganization energy (λtotal) and injection driving force (ΔGinject) have been explained. As a result, the calculated data verify that the D dye can represent a potential sensitizer for solar cells, this can be rationalized by its reasonable photovoltaic parameters with other electronic and optical properties.

Influence of the dipole moment on the photovoltaic performance of polymer solar cells employing non-fullerene small molecule acceptor

A new narrow bandgap non-fullerene acceptor with a DPP core and dicyanorhodanine terminals linked by selenophene spacers has been synthesized. Optical and electrochemical properties of MPU5 were examined and compared to that of its comparable MPU2, which contains thiophene linkers instead of selenophene. MPU5 has a lower optical bandgap (1.38 eV) than MPU2 (1.41 eV), this may be due to the higher electron richness and lower aromatici character of selenophene, comparative to thiophene, favoring a quinoidal structure and intramolecular charge transfer between push–pull moieties. MPU5 was employed as the electron acceptor in conjunction with a conjugated polymer (PCDTBT) as donor with a complementary absorption (350–650 nm) and high HOMO and low LUMO energy levels (–5.4 eV and –3.6 eV, respectively) for the fabrication of polymer solar cells using a bulk heterojunction active layer. The MPU5-based polymer solar cell enabled an overall power conversion efficiency (PCE) of 10.10% with an Eloss of 0.43 eV with an optimized bulk heterojunction active layer. These values are better than those for the MPU2 counterpart (PCE = 8.04%, Eloss = 0.56 eV). The higher PCE obtained for the MPU5-based polymer can be correlated with better balanced charge transport, appropriate active layer nanoscale morphology, efficient charge extraction and longer charge carrier lifetime, resulting in an improvement in the Jsc and FF values. The superior Voc value for the MPU5-based polymer may be related to the lower energy loss caused by the larger dipole moment and dielectric constant of MPU5, which result in a smaller exciton binding energy in the active layer.

Studies on photophysical and electrochemical properties of triphenylamine α, β-unsaturated ketone side-arm PAE CPs

A series of polyaryleneethynylene (PAE) conjugated polymers (CPs) have been synthesized using 1-(4-((2,5-diethynylphenyl)ethynyl)phenyl)-3-(4-(diphenylamino)phenyl)prop-2-en-1-one, 1,4-diiodo-2,5-bis(octyloxy)benzene, 1,4-bis(dodecyloxy)-2,5-diiodobenzene and 2,7-diiodo-9,9′-dioctyl-9H-fluorene with terminal hydrogen presented diethynylene and diiodo–substituted precursor as acceptor and donor monomers. The donor and acceptor (D-A) unit network of CPs developed through the Heck–Sonogashira cross-coupling reaction mechanism. The triphenylamine attached α,β unsaturated ketone of phenylethynylene side-arm PAE CPs was studied for their photophysical and electrochemical behaviors based on the molecular-level electronic properties. From the solution-phase UV–visible (UV–Vis) and Fluorescence (FL) measurements explained the π–π* electronic transition and intramolecular charge transfer (ICT) behavior of the CPs. The shift between UV–Vis maxima and FL maxima are well accounted for calculating the Stokes shift, which supports the evidence for the red shift of PAE CPs, namely NPAEC8-127 nm, NPAEC12-131 nm, and NPAEF8-25 nm. The thin-film UV–Vis absorption spectra and electrochemical measurements ascertain the existence of the optical low band gap (Eg) (NPAEC8-2.57 nm, NPAEC12-2.62 nm, and NPAEF8-2.70 nm) and HOMO–LUMO energy levels of the PAE CPs. Based on data obtained from different studies, it is suggested that the synthesized PAE CPs are suitable for the photovoltaic and sensor applications.

Cu(I) complexes sensitized ZnO nanorods for photocatalytic water splitting

The earth-abundant Cu(I) is one of the promising dye-sensitized photoelectrochemical cells (DS-PECs) for sustainable energy production. We report that the heteroleptic Cu (I) complex's catalysis consisting of diphenylphosphinoaminoacetic acid and bipyridine derivatives have investigated with DS-PECs on water splitting application. HOMO-LUMO energy levels of 2,2′bipyridine Cu(I) diphenylphosphinoaminoacetic acid (Cu(L1)) 4,4′dimethyl-2,2′bipyridineCu(I)diphenyl phosphinoaminoacetic acid (Cu(L2)) are calculated with cyclic voltammetry and Uv-vis spectrometer. Both optic band gap and electrochemical band gap energy levels of Cu(I) complex indicates that Cu(L1) has a narrower band gap (2.74 eV and 2.75 eV) compared with Cu(L2) (2.86 eV and 2.79 eV). The photocatalytic hydrogen production of Cu(L1) and Cu(L2) complexes on ZnO nanorods are monitored with linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) in 0.5 M Na2SO4 under 100 mW cm−2 solar light irradiation. Cu(L1) modified ZnO nanorod photoelectrode indicates an utmost photocatalytic response (0.452 mA cm−2), the lowest charge transfers resistance (Rct) against to bare the ZnO and Cu(L2)/ZnO electrodes, and Cu(I) complex decreases injected electron lifetime leading to the enhanced photocatalytic response under solar light irradiation.

Synthesis, crystal structure, DFT calculations, Hirshfeld surface analysis, energy frameworks, molecular dynamics and docking studies of novel isoxazolequinoxaline derivative (IZQ) as anti-cancer drug

Quinoxaline derivatives with the molecular formula [C8H6N2] also named benzopyrazines, which are a valuable class of heterocyclic compounds useful for their numerous industrial and pharmaceutical applications. The new isoxazolquinoxalin (IZQ) 3-phenyl-1-((3-(p-tolyl)-4,5-dihydroisoxazol-5yl)methyl)quinoxalin-2(1H)-one (5) has been synthesized with good yield by stirring the compounds of 1-allyl-3-phenylquinoxalin-2(1H)-one (3, 3.8mmol), and (E)-4 methylbenzaldehydeoxime (4, 1.3mmol) in 20 ml of chloroform. The aqueous solution of sodium hypochlorite (10 ml of water bleach 12°) was added drop wise using bromine funnel. The mixture was stirring at 0°C temperature for 6 hours. Then it dried to obtain a crude product which on recrystallization with ethanol afforded the title compound (5) as colourless rectangular block shape crystals, and then confirmed by H NMR, LC-MS spectra. The structure of the compound has been confirmed by single crystal X-ray diffraction technique. The compound crystallizes in the monoclinic crystal system with the space group P21/c. The unit cell constants; a =15.9437(6) Å, b =16.3936(6) Å, c =7.4913(3) Å, and β =94.178(2)o. DFT calculations were carried out and HOMO-LUMO energy levels have been determined. In the structure, both Intermolecular and intramolecular hydrogen bonds of the type C-H...O were observed along with C-H...cg interactions. Hirshfeld surface studies were performed to understand the different interaction contacts of the molecule and the molecular packing strength of the crystal. Energy frameworks were constructed through different intermolecular interaction energies to investigate the stability of the compound and to know type of the dominate energy. Docking studies predicted anti-cancer activity of the title molecule against homo sapiens protein (pdb code:6HVH) and exhibited prominent interactions at active site region.

Quantum chemical insight into molecular structure, spectroscopic and nonlinear optical studies on methylene bis(dithiobenzoate)-=SUP=-*-=/SUP=-

In this study, the methylene bis(dithiobenzoate) molecule, (C15H12S4), as a bioactive molecule has been subjected to quantum chemical computations using density functional theory (DFT) in order to investigate the molecular geometry, IR, UV-visible and NMR spectral studies. The title molecule has been optimized at the B3LYP, B3PW91 and PBE11PBE levels of DFT and 6-311G(d,p) basis set. Furthermore, the vibrational frequencies, the HOMO-LUMO energy levels, the 1H and 13C NMR chemical shifts (ppm), nonlinear optical properties calculations of the title compound were obtained by B3LYP, B3PW91 and PBE1PBE levels. The maximum electronic transition wavelengths, oscillator strengths, excited state and transition dipole moments for the title compound were also investigated by B3LYP, B3PW91 and PBE1PBE levels of time-dependent (TD)-DFT. Keywords: methylene bis(dithiobenzonoate), IR and UV-vis spectroscopy, 1H and 13C NMR chemical shifts, NLO DFT method.

Computational investigations, Hirshfeld surface analysis, interaction energy calculations, and energy framework crystal structure of methyl 2-amino-5-hydroxybenzoate

The title compound with the molecular formula C8H9NO3 is synthesized by refluxing 2-amino-5-hydroxybenzoic acid in methanol. The molecular structure of the compound is determined by single crystal X-ray diffraction. Methyl 2-amino-5-hydroxybenzoate crystallizes in the orthorhombic space group P212121 with a = 4.973(2) Å, b = 10.923(5) Å, c = 14.074(6) Å, Z = 4 and V = 764.4(6) Å3. DFT is used to compute HOMO—LUMO energy levels, to predict the reactivity of substituents (NH2 and OH), and to determine the nucleophilic character of these two groups. The orientation and nature of substituents on benzene favors the formation of a stable six-membered ring via hydrogen bonding which plays a key role in the properties of the investigated compound. The natural bond orbital (NBO) population analysis demonstrates that the hyperconjugative effect between the donor lone pairs located on the carbonyl oxygen atom and the N—H group, via the lp O → σ*(N—H) 1,6-remote interaction, is responsible for the preferred conformation. The molecular electrostatic potential (MEP) surface shows the electrical neutrality in the molecule. To get an insight to the intermolecular interactions in the crystal a Hirshfeld surface analysis is also carried out.

Theoretical Study of the Stability and Vibration Spectrum of C<sub>38</sub>Cl<sub>2</sub>

In this study, the theory of density functional was used to geometrically optimize the binary chlorine-derived isomers of C₃₈ at the b3lyp/6-31g(d) level. Analysis of the reaction heat and HOMO-LUMO of the optimized structure shows that C₃₈Cl₂ is thermodynamically stable; The 1-8 added isomer 10-C₃₈Cl₂-2-37 and The 1-4 added isomer 17-C₃₈Cl₂-12-27 was the most stable among the molecules studied. Derivatization mostly occurs on the carbon atom with the most negative charge, which is generally the common vertex of three five membered rings. Chlorination derivatization reduces the HOMO energy level of the carbon cage, increases the HOMO-LUMO energy level gap of the carbon cage, and reduces the reaction activity of the carbon cage. The vibration frequency calculation shows that the addition mode and symmetry will affect the maximum vibration frequency and intensity of the structure. The strongest vibration is generally C-Cl telescopic vibration. The higher the derived position symmetry, the greater the vibration intensity.

Synthesis and third-order nonlinear optical properties of low band gap 3,4-ethylenedioxythiophene-thiophene copolymers

Alternate donor–acceptor 3,4-ethylenedioxythiophene (EDOT) based copolymers with thiophene and 3-methyl thiophene were designed by employing density functional theory (DFT) in the periodic boundary condition using HSE06 exchange correlation functional and 6-31G basis set. The designed copolymers were synthesized via a simple and facile route, i.e., direct arylation and their third-order nonlinear optical properties were investigated by Z-scan technique. The resultant copolymers, P(EDOT-THP) and P(EDOT-MeTHP) were characterized by spectroscopic analysis. The photophysical and electrochemical properties of EDOT-thiophene copolymers were investigated by UV–visible spectra and cyclic voltammetry, respectively. The copolymers revealed low band gap and better electronic properties as compared to the homopolymers. The introduction of EDOT unit in the polythiophene leads to decreased HOMO-LUMO energy levels, and the absorption spectra was red shifted when compared with that of the parent compound. The nonlinear absorption and nonlinear refraction coefficient of copolymers have been investigated at 532 nm. The optical limiting properties of copolymers have also been measured. The copolymers exhibited strong optical nonlinearity owing to the presence of alternate donor-π-acceptor scheme in the polymers.

Aggregation-Induced Emission Behavior of Dual-NIR-Emissive Zinc-Doped Carbon Nanosheets for Ratiometric Anthrax Biomarker Detection

The development of near-infrared (NIR) emission nanoprobes for the ratiometric fluorescent determination of living cells in vitro/vivo is of great analytical importance. In this work, dual-NIR-emissive Zn-doped carbon-based nanosheets (Zn-CNSHs) were prepared with a beneficial and special donor-π-acceptor-conjugated (D-π-A-conjugated) spatial framework, which resulted in not only a much lower HOMO-LUMO energy level but also excellent biocompatibility and physicochemical properties. The Zn-CNSHs were prepared by simple one-pot solvothermal synthesis with zinc gluconate (ZGN) and a strong acid and exhibited two distinctive photoluminescence (PL) peaks at 620 and 720 nm with the 600 nm excitation. The 620 nm peak intensity was dependent on dipicolinic acid (DPA) owing to the aggregation-induced emission enhancement effect via the strong intersheet hydrogen bonds between Zn-CNSHs and DPA, enabling the ratiometric fluorescent determination of DPA, an important clinical anthrax biomarker. An excellent calibration curve showed linear regions over the range of 0.05-500 μM between the ratio of PL intensity (PL620nm/PL720nm) and the concentrations of DPA. The detection limit was down to 21.7 nM. Based on the high stability, low cytotoxicity, high selectivity, and outstanding PL-reliant sensitivity for the DPA assay, the nanoprobe has been successfully used to monitor DPA in serum, wastewater, and cells.

HOMO-LUMO Energy Levels and the Bandgaps to Understand Porpc Photocatalytic Activity

A dye-sensitized solar cell (DSSC) assembly can be used not only to harvest solar energy but also to purify water using suitable dye-sensitizers. Here, we theoretically investigated four dye-sensitizers, namely, PORPC-1, PORPC-2, PORPC-3, and PORPC-4 for photocatalytic water purification using PBE, B3LYP, PBE0 functionals, and ∆SCF, TD-DFT and GW methods to characterize their activity trends. The energy levels of highest occupied molecular orbitals (HOMO) and the lowest unoccupied molecular orbitals (LUMO) were elucidated using gas-phase and aqueous phase calculations to understand charge injection ability and the dye-regeneration process. However, PBE, B3LYP, PBE0, and TD-DFT methods fail to predict the best sensitizers. The ∆SCF coupled with the implicit solvation method and the GW method HOMO-LUMO energies corrected for aqueous environment effect predicted PORPC-2 and PORPC-4 as the best sensitizers. Thus, it emphasized the importance of aqueous environment effect in simulation. However, none of these methods accurately predicted the photocatalytic performance trend of all the four dye-sensitizers. Hence, we have used the dye-molecular aggregation assembly pattern in an aqueous environment to further probe into activity trends and found that the PORPC-3 and the PORPC-4 prefer J-aggregate assembly, whereas the PROPC-1 and the PORPC-2 adopt H-aggregate assembly pattern. Therefore, the synergistic effect of the HOMO-LUMO energy levels and the aggregate assembly pattern determine the photocatalytic performance of the dye-molecules, and the activity trend is PORPC-4>PORPC-2>PORPC-3>PORPC-1, agreed well with the experimental findings. Acknowledgements This study was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (Nos. NRF-2017R1E1A1A01074266, NRF-2015M1A2A2057129, and NRF-2016M1A2A2937151).

Synthesis and characterization of new polymers derived from 2-methyl-m-phenylenediamine as an effective adsorbent for cationic dye removal

The oxidative polymerizations of 2-methyl-m-phenylenediamine were performed to synthesize PMPDIA-A and PMPDIA-B polymers by H2O2 (35% aqueous solution) oxidant in acid-catalyzed ethanol and basic aqueous medium. Furthermore, PMPDIA-E polymer of 2-methyl-m-phenylenediamine was enzymatically synthesized by HRP (horseradish peroxidase) enzyme and H2O2 (35% aqueous solution) in dioxane/0.1 M phosphate tampon solution (pH = 7) mixture. The structures of 2-methyl-m-phenylenediamine and polymers were confirmed by FT-IR, NMR and UV–Vis spectrometer measurements. Molecular weight distributions, surface morphologies, thermal and fluorescence properties of polymers were determined from GPC, SEM, TG-DTA, DSC and fluorescence spectra analyses, respectively. CV and UV–Vis analyses were performed to determine the HOMO–LUMO energy levels, electrochemical (Eg′) and optical (Eg) band gaps values of MPDIA, PMPDIA-E, PMPDIA-A and PMPDIA-B. The electrochemical and optical band gaps values of polymers were lower than MPDIA, because of their polyconjugated structures. According to GPC measurements of polymers, the weight average molecular weights were between 5400 and 10400 Da. The fluorescence quantum yield of PMPDIA-E was calculated to be 9.15% in DMSO solution. The adsorption of methylene blue (MB) from aqueous solution on PMPDIA-B was studied. Adsorption isotherms and equilibrium adsorption capacities were determined by the fitting of the experimental data to two well-known isotherm models: Langmuir and Freundlich.

Quantum mechanical calculations of different monomeric structures with the same electroactive group to clarify the relationship between structure and ultimate optical and electrochemical properties of their conjugated polymers

Quantum mechanical calculations can clarify the relationship between structure and ultimate optical and electrochemical properties of conjugated polymers and produce a ground for the design of advanced materials for futuristic applications. Herein, we have examined the structural geometries and electronic properties of different monomeric structures with the same electroactive group to provide a relationship between calculated electronic properties of the monomers with the observed optical and electrical properties of their conjugated polymers. For this purpose, three different amide substituted 2,5-di(2-thienyl)-1H-pyrrole compounds containing a different number of electroactive groups have been synthesized and molecular structure optimizations have been carried out with the Density Functional Theory (DFT) calculations. FT-IR and NMR spectra of optimized geometries have been compared with experimental data. Furthermore, electronic properties of the monomeric structures such as chemical hardness/softness, ionization potential, HOMO-LUMO energy levels, electronegativity have been revealed and molecular electrostatic potential (MEP) surface has been calculated to determine the electrophilic and nucleophilic reactive attack regions of the molecules considered in this study. Finally, Total Density of State (TDOS), Partial Density of State (PDOS) and Mulliken charge analyses of these molecules have been carried out. Our calculations based on ab-initio methods for the monomers have been compared with the optical and electrical properties of their conductive polymers in order to understand interrelationship between monomer structure and polymer properties.

Multi-functionalized polysilsesquioxanes assisted synthesis of methylammonium tin bromide perovskite: A novel approach

Polymeric encapsulants are proven to be defect-passivating agents which render robust perovskite films. Here, we report the new approach of synthesis of tin halide perovskite encapsulated by a transparent conducting oligomer, namely polysilsesquioxane (PSQ). The stability of the tin halide perovskite was improved using the modifier. PSQ possesses good electrical conductivity and HOMO-LUMO energy levels being suited for promoting the hole conductivity of the perovskite materials. The crystal structure, morphology, optical properties, and current-voltage characteristics of PSQ encapsulated perovskites were studied using microscopic, spectroscopic and photovoltaic characterization techniques. Photovoltaic cells were fabricated under ambient atmosphere (RH >60%) and photovoltaic conversion efficiencies (PCEs) of ~2.2% were obtained with a short-circuit current density (JSC) of ~5.4 mA/cm2, open circuit potential (VOC) of ~1.0 V and a fill factor (FF) of ~40% under 1 sun (100 mW/cm2) illumination. Our work opens a new class of chemical modifiers for improving environmental stability and can be further tuned for the development of more efficient photovoltaic conversion devices.

Dithienopyrrolobenzothiadiazole-based metal-free organic dyes with double anchors and thiophene spacers for efficient dye-sensitized solar cells

Five new dithienopyrrolobenzothiadiazole (DTPBT)-based organic sensitizers were prepared for dye-sensitized solar cells (DSSCs). In this work, DTPBT unit was used as a donor to construct mono- and di-anchored metal-free organic sensitizers for the first time. The DTPBT unit applied as a donor or a π-spacer in mono-anchored dyes (W1 and W2) greatly influences the absorption range, HOMO-LUMO energy level and the solar cell performance of the dyes. The results show that the DTPBT unit is more suitable for acting as a π-spacer in D-π-A dyes. Di-anchored dyes exhibit broader photo-spectra response and higher molar extinction coefficients than those of the mono-anchored dyes. Di-anchored dyes W4 and W5 with DTPBT as the donor, thiophene as the π-bridge achieve high power conversion efficiencies of 7.93%, 7.98% with 1 mM CDCA as the co-adsorbent, respectively. The results suggest that the DTPBT moiety is a promising donor candidate to develop efficient double anchored organic dyes for DSSCs.

Quantum chemical analysis of harmful dye 3-[ (4-anilinophenyl) diazenyl] benzenesulfonate, metanil yellow

In the present work, quantum chemical study of the harmful dye, metanil yellow is conducted. The optimized molecular geometry and harmonic vibrational frequencies of metanil yellow were calculated by DFT-B3LYP method with LANL2DZ basis set. The vibrational assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes. Infrared spectra and Bulk Raman spectra were also obtained and characteristic peaks for the title compound were studied. The nonlinear optical properties of the title compound were calculated and discussed. Dipole moment, polarizability and first-order hyperpolarizability of the title compound were reported in order to study nonlinear optical properties (NLO). HOMO-LUMO energy levels were also computed in order to get the bandgap energy. Global reactivity descriptors were calculated using the HOMO and LUMO to predict compound reactivity. UV–Vis spectrum of the title compound was calculated using TD–DFT method. The molecular orbital contributions were studied by density of states (DOSs). Mulliken atomic charges and atomic polar tensors (APT) on each atom were tabulated. A discussion of the vibrational energy of each mode is also presented in this article.  Â

Rational design of Ru(II)-phenanthroline complex embedded porous TiO2photocatalyst for efficient hydrogen production

Abstract The design of an efficient photocatalytic system with a capability of effective photon conversion for hydrogen evolution is highly challenging. Herein, we report the first example of phenanthroline based ruthenium complexes (PRC1-3) embedded nanostructured hierarchical porous TiO2 composites (HPT) that showed impressive H2 evolution reaction (HER) under simulated light irradiation. The introduction of the propenyl groups in the Ru-Phen complexes reveal enhanced light response (350–550 nm) with increased charge transfer behaviour and lifetime of 77–127 ns. The composite PHPT-PRC’s endows high performance towards HER. The superior activity of PHPT-PRC3 exhibits H2 yield of 3066 μmolg−1cat with a turnover number of 123 after 4 h compared to N719 sensitized PHPT (N719-PHPT). The enhancement in HER is due to the strong photon absorption in PRC3 with 3-propenyl moieties with an extended excited state lifetime. Further, the high surface area and uniform porous structures of HPT favours better transport of irradiated light absorption and enhanced charge transfer property which synergistically improves the effective charge transfer on the photocatalytic HER. The experimental observations corroborated with computational calculations which further elucidates the high efficiency of PRC3 than 1 and 2 due to favourable HOMO-LUMO energy levels, efficient charge separation and enhanced regeneration of oxidized dye.

Optical and electrochemical recognition studies of anions via novel benzothiazole azo-derivative

Herein, a novel supramolecular probe 4-(2-phenyldiazenyl)-2-(benzothiazol-2-yl) phenol (1) has been described, where assimilation of benzothiazole unit with azo functionality led to innovative electrochemical and optical response towards anions. The successful formation was confirmed using 1HNMR, 13C NMR and HRMS. This rationally planned receptor 1 exhibits multi recognition modes in showing selectivity towards AcO- and F- anions by both visual and absorption processes; while I- is sensed selectively via redox mechanism. The multi recognition mechanisms were thoroughly documented by DFT giving an insight picture of the mode of interaction of the anions in HOMO-LUMO energy levels ultimately affecting the activity of the designed benzothiazole moiety. Optimization of various parameters related to redox response was also analyzed by Taguchi method to minimize the effect of uncontrollable variables. Lower detection limit for the anions by different response mechanisms in a single moiety enhances the future possibility of an economic and time saving multichannel chemosensor.