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Three new π-conjugated semiconductors of the type D–π–D, A–π–A (symmetric), and D–π–A (asymmetric) were constructed on fluoreno-thiophene spacer by permutation of the lateral groups such as diphenylaminostyryl and dicyanovinyl as electron donor (D) and acceptor (A), respectively. The influence of the asymmetric push–pull effect (as in D–π–A) on the optical as well as the electrochemical properties has been evaluated and compared with the symmetrical D–π–D and A–π–A systems. Theoretical investigation of the molecular properties using DFT/TD-DFT calculations was found to be in good agreement with the experimental results. The chromophore with an asymmetric push–pull architecture emerged as a better candidate for organic solar cell fabrication in terms of its optical band gap, HOMO–LUMO energy level, surface morphology, crystallinity, and charge carrier mobility. The photovoltaic performance of the synthesized chromophores in the bulk heterojunction solar cells revealed a power conversion efficiency of 2.01% for the asymmetric chromophore (D–π–A), which is better than the symmetrical counterparts (D–π–D and A–π–A). Overall, this work demonstrates the impact of symmetric and asymmetric push–pull switch within the fluoreno-thiophene π-molecular backbone on the modulation of the optoelectronic properties.

FTIR spectroscopic studies has been carried out on pure toluene (TOL), propionitrile (PN) and their equimolar binary solution at room temperature. DFT calculations (using B3LYP functional with the Grimme's dispersion correction D3 and ωB97XD with the D2 version of Grimme's dispersion) have also been carried out on PN dimers and various TOL-BN heteroassociated networks that are supposed to exist in neat PN and binary solution, respectively, on the basis of the shifts suffered by the fundamental absorptions of TOL and PN upon mixing with each other. Formation of ( m e t h y l ) C − H ⋯ N ≡ C and ( m e t h y l e n e ) C − H ⋯ N ≡ C hydrogen bonded dimers in neat PN has been identified. The dominant interaction forces that stabilize the 1:2 (TOL: PN) complex formed in the binary solution are ( T O L m e t h y l ) C − H ⋯ N ≡ C and ( T O L r i n g ) C − H ⋯ N ≡ C intermolecular H-bonds.

The hybrid molecular materials [Fe(C5H5)2]3[PW12O40]·(H2O)4 and [Fe(C5H5)2]3[PMo12O40]·(H2O)6, denoted respectively as FcPW and FcPMo, are synthesized via a co-precipitation method under acidic conditions (pH: ∼2–3). The molecular properties of these compounds are investigated via various analytical methods. UV-vis diffuse reflectance and photoluminescence studies confirm that these compounds are charge-transfer salts. Stainless steel plates (SS, 316 grade) coated with these hybrid compounds and dipped in 0.5 M H2SO4 and Ringer's solutions show significantly inhibited corrosion. The corrosion inhibition properties of these materials are studied via weight loss, electrochemical impedance spectroscopy, and potentiodynamic polarization studies. The reproducibility of the corrosion inhibition results is ensured via repeat measurements, and error values are reported. The surfaces of the corroded steel plates are examined via scanning electron and atomic force microscopy techniques. It is found that the corrosion is of uniform type. The Tafel extrapolation method shows that the inhibition efficiency is 74% for SS@FcPMo and 65% for SS@FcPW. The corrosion inhibition mechanism is explained based on the redox nature of the hybrid materials. The experimental results are corroborated through computational studies carried out using a first principles approach with the optimized geometries and frontier molecular orbitals of the hybrid molecular materials.

Neutral phosphine oxide (P[double bond, length as m-dash]O) donor-based organometallic complexes [{Re(CO)3O[double bond, length as m-dash]PCy3}{μ-DHBQ}{Re(CO)3O[double bond, length as m-dash]PCy3}] (1), [{Re(CO)3O[double bond, length as m-dash]PPh3}{μ-DHBQ}{Re(CO)3O[double bond, length as m-dash]PPh3}] (2), [{Re(CO)3O[double bond, length as m-dash]PCy3}{μ-THQ}{Re(CO)3O[double bond, length as m-dash]PCy3}] (3), [{Re(CO)3O[double bond, length as m-dash]PPh3}{μ-THQ}{Re(CO)3O[double bond, length as m-dash]PPh3}] (4), [{Re(CO)3O[double bond, length as m-dash]PCy3}{μ-CA}{Re(CO)3O[double bond, length as m-dash]PCy3}] (5), and [{Re(CO)3O[double bond, length as m-dash]PPh3}{μ-CA}{Re(CO)3O[double bond, length as m-dash]PPh3}] (6) were assembled from phosphine/phosphine oxide, a dihydroxybenzoquinone donor and Re2(CO)10via a one-pot solvothermal approach. The soft phosphine donor was transformed into a hard phosphine oxide donor during the formation of 1, 3, 4, 5, and 6. The complexes 1-6 were air and moisture stable and were soluble in polar organic solvents. The complexes were characterized by elemental analysis, FT-IR, and NMR spectroscopic methods. The molecular structures of 1, 2, 4, and 6 were analyzed by single-crystal X-ray diffraction analysis. The UV-Visible absorption studies indicated that 1-6 in THF display strong visible light absorption in the range of ∼350-700 nm.

In the present study strontium oxide/graphitic carbon nitride (SrO 2 /g-C 3 N 4 ) nanohybrids was successfully synthesized by a facile simple dry synthesis and used for the photocatalytic degradation of organic contaminants for the very first time. The SrO 2 /g-C 3 N 4 nanohybridsare having a superior crystallinity and crystallite size was ∼7.1 nm. The photodegradation efficiency of nanohybrids was tested on the degradation of RhB dye solution under visible light irradiation. The SrO 2 /g-C 3 N 4 nanohybrids exhibited excellent photocatalytic activity, which may be attributed to the improved charge separation and complete degradation of the dye solution is achieved within 60 min. Moreover, the synthesized nanohybrids exhibited a good stability towards the photodegradation of RhB dye. Finally, the possible mechanism for the charge separation in thephoto degradationprocess wasexplored. Therefore, the nanohybrids are possessing potential interest in waste water treatment and environmental remediation under visible light irradiation.

FTIR spectra of neat acetonitrile (AN), dimethyl sulphoxide (DMSO) and their binary solutions at various mole fractions have been recorded at room temperature. Theoretical calculations have also been carried out on acetonitrile (monomer, dimer), dimethyl sulphoxide (monomer, dimer) and AN – DMSO complex molecules. 1:2 (AN:DMSO) and 2:1 complexation through the red shifting ( A N ) C − H ⋯ O = S ( D M S O ) and blue shifting ( D M S O ) C − H ⋯ N ≡ C ( A N ) hydrogen bonds has been identified. The experimental and theoretical studies favour the presence of both the monomer and dimer in liquid AN, but only closed dimers in DMSO. The dipole-dipole interactions existed in AN and DMSO dimers disappear in the complex molecules. Partial π bond between S and O atoms, and three lone pair of electrons on oxygen atom of DMSO have been noticed theoretically.

Dielectric studies using Time Domain Reflectometry method has been carried out on the binary solution of Ethyl acetate (EA) with Chlorobenzene (CBZ) over the entire composition range. Spectroscopic (FTIR and 13C NMR) signatures of neat EA, CBZ and their equimolar binary solution have also been recorded. The results of the spectroscopic studies favour the presence of (CBZ) C H ⋯ O C (EA), (EA) methylene C H ⋯ π electrons (CBZ) and (EA) methyl C H ⋯ Cl (CBZ) contacts which have been validated using quantum chemical calculations. Dimerization of CBZ has been identified. Presence of β-clusters has been identified in all the solutions. Although EA and CBZ molecules have nearly equal molar volumes, CBZ molecules experience larger hindrance for the rotation than EA molecules. Very small excess dielectric constant (eE) values may be correlated with weak heteromolecular forces and/or closed heteromolecular association.

FTIR spectra of neat acetone, ethanol and their binary solutions at the molar ratios 0.2:0.8 (ethanol: acetone), 0.4:0.6, 0.6:0.4 and 0.8:0.2 have been recorded at room temperature. Theoretical calculations have also been made on acetone (monomer and dimer), ethanol monomer, dimer, trimer, tetramer, pentamer, hexamer and ethanol - acetone complex molecules. 4:1 (ethanol:acetone), 5:1 and 6:2 complexation through the classical C O⋯H O and (acetone) C H⋯O C(ethanol ) hydrogen bonds has been identified. Ethanol rich solutions may consist of ethanol multimers such as tetramer, pentamer and hexamer along with 4:1, 5:1 and 6:2 complex molecules depending upon ethanol concentration. Acetone seems to exist as a mixture of monomer and dimer.

Metal cluster, at sub-nanometer level has a unique property in the activation of small molecules, in contrast to that of bulk surface. In the present work, singly exposed active site of copper metal cluster at sub-nanometer level was designed to arrive at the energy minimised configurations, binding energy, electrostatic potential map, frontier molecular orbitals and partial density of states. The ab initio molecular dynamics was carried out to probe the catalytic nature of the cluster. Further, the stability of the metal cluster and its catalytic activity in the electrochemical reduction of CO 2 to CO were evaluated by means of computational hydrogen electrode via calculation of the free energy profile using DFT/B3LYP level of theory in vacuum. The activity of the cluster is ascertained from the fact that the copper atom, present in a two coordinative environment, performs a more selective conversion of CO 2 to CO at an applied potential of −0.35 V which is comparatively lower than that of higher coordinative sites. The present study helps to design any sub-nano level metal catalyst for electrochemical reduction of CO2 to various value added chemicals.

From the FTIR spectral studies on neat acetonitrile (AN), methyl cellosolve (MCS) and their binary solutions at different compositions, ( M C S ) O − H ⋯ N ( A N ) , ( M C S m e t h y l a n d / o r m e t h y l e n e ) C − H ⋯ N ( A N ) and ( A N m e t h y l ) C − H ⋯ O ( M C S h y d r o x y l a n d / o r e t h e r e a l ) heterointeractions have been identified. DFT calculations show that MCS multimerization and AN dimerization are through ( M C S h y d r o x y l ) O − H ⋯ O ( e t h e r i c o x y g e n o f M C S ) and ( A N m e t h y l ) C − H ⋯ N ( A N ) interactions, respectively. Two different geometries of 1:4 (AN: MCS) complexes and 1 type of 2:4 (AN: MCS) complex have been formed in the solutions. Of the three, 2:4 (AN:MCS) complex is the most stable one as suggested by the interaction energies. 2:4 complexation occurs in the binary solution in which AN concentration is one fourth of the MCS concentration.

Three new dipolar organic dyes of the type D-D-π-A were constructed on fluorenothiophene backbone by varying the terminal donor auxiliary such as -NMe2, -NEt2 and -NPh2. The effect of such structural variation on the photophysical and electrochemical properties has been investigated. Computational studies obtained from DFT/TD-DFT calculations were found to be in good correlation with the experimental optoelectronic results. TiO2 based n-type quasi-solid state DSSCs constructed on the synthesized dyes revealed a gradual increase in photovoltaic performance with increase in donor size. The trend in power conversion efficiency (η) was found to be -NPh2 (4.10%) > -NEt2 (3.44%) > -NMe2 (2.57%). Electrochemical impedence analysis also confirmed the longer electron life time for dye possessing bulky -NPh2 groups in comparision to -NEt2 and -NMe2 groups, thus demonstrating the impact of increased donor size on the DSSC performance. Overall, this paper validates the impact of donor size on the DSSC performance and could inspire the selection of appropriate auxiliary donors to enhance the efficiency in futuristic endeavors.

Selective detection of sulfur mustard simulant, 2-chloroethyl ethyl sulfide (CEES) is performed using specifically designed pyridine appended Mg–porphyrazine complex (1). Interaction of CEES with pyridine units of 1 leads to perturbation/reduction in absorbance of the Q-band of 1 and the process is, thus, monitored using UV–vis spectroscopic method. Interestingly, treating the CEES-1 solution with KMnO4 solution results in reappearance of Q-band of 1 and allows reuse of 1 by simple filtration. The alkylating ability of CEES and KMnO4 oxidation of CEES-1 appears to be playing an important role in the detection/degradation process, thereby serving the dual purpose. The chemical sensing is then used as a platform for generating different input-based combinatorial and sequential molecular logic gate(s) allowing facile information processing and as an information security system in the form of a keypad lock.

Green synthesis of Au-NPs using Cerasus serrulata (C. serrulata) leaves extract has emerged as a nontoxic and ecofriendly option, as compared to currently available chemical and/or physical methods and also Au-NPs act as both reducing and stabilizing agent. The developed Au-NPs were characterized with XRD, UV–visible spectroscopy, FTIR, SEM, TEM and chemical constituents of C. serrulata leaves extract after and before reduction of Au-NPs have been identified through GC–MS. TEM images confirmed that biosynthesized Au-NPs were spherical in shape and approximately in the range of 5–25 nm. The electrochemical results showed remarkable electrocatalytic activity of the Au-NPs-modified GC electrode in the detection of environmentally hazardous pollutant like hydrazine. The modified electrode exhibits a wide linear range 5 nM to 272 μM with low detection limit 0.05 μM. The fabricated sensor shows good selectivity towards other electroactive species as well. Thus the proposed sensor seems to be a potential candidate for developing a simple, rapid and cost-effective electrochemical sensor. The synthesized Au-NPs exhibited higher antibacterial activity against gram negative (Escherichia coli) than gram positive (Staphylococcus aureus) bacteria. DFT studies revealed that the coumarin (CM) present in the C. serrulata leaves extract demonstrated greater reducing and stabilizing properties compared to the properties of other compounds like butylhydroxytoluene (BHT) and hydrocoumarin (HCM) present in the extract.

Binary mixtures of benzene + methyl acrylate/butyl acrylate were prepared over the entire composition range which were subjected to dielectric and spectroscopic (FTIR, 13C NMR and UV–vis) studies. The parameters such as Kirkwood correlation factor, excess dielectric constant etc. are interpreted with the aid of spectroscopic results which revealed the existence of blue and red shifting hydrogen bonds in both the mixtures. 13C NMR and excess free energy ∆ G favor the presence of self-associated molecular aggregates in neat methyl acrylate/butyl acrylate.

Developing new efficient catalysts for the electrochemical reduction of carbon dioxide to formic acid is important in the process of mitigating environmental CO2. In the present work, we have designed metal (M) clusters anchored on a polyaniline (PANI) conducting polymer electrode (M@PANI), where, M = Ni, Pd, Pt, Cu, Ag & Au, and evaluated their potential catalytic activity towards CO2 reduction by means of computational hydrogen electrode using hybrid density functional theory methods. The predicted binding energy and electronic properties of M@PANI suggest a thermodynamically feasible reaction which retains its conducting property with enhancement. The modified electrodes favour the formation of HCOOH involving H*COO species via the formate pathway. The computed limiting potentials suggest that Cu@PANI is a suitable electrode material for the CO2 reduction reaction leading to HCOOH.