Structural investigation, spectroscopic and energy level studies of Schiff base: 2-[(3′- N -salicylidenephenyl)benzimidazole] using experimental and DFT methods (original) (raw)
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A benzothiadiazole based solution-processable organic dye D1 (N 4-Phenyl-N 4 ,N 7 ,N 7-tri{4-[(2-ethoxycar-bonyl)-2-cyanovinyl]phenyl}benzo[c][1,2,5]thiadiazole-4,7-diamine) was synthesized. Dye-sensitized solar cells (DSSCs) were fabricated based on D1 and a commercially available benzothiadiazole based RK1 dye. The photo-voltaic parameters of these cells were studied under simulated AM 1.5 illumination (100 mW cm-2). The DSSC sensitized by RK1 dye provided a power conversion efficiency of 5.7 % with high values of short-circuit pho-tocurrent density, open-circuit photovoltage, and fill factor. Under the same conditions, the cell sensitized with D1 dye showed a very poor performance due to the lower values of short-circuit photocurrent density and open-circuit photo-voltage. In order to provide insight into poor performance of the DSSC sensitized by D1, molecular structure of D1 was analyzed by density functional theory. Its frontier orbitals were calculated to investigate effectiveness of charge transport and reasons of the poor performance. This computational study revealed that the photovoltaic performance of the benzothiadiazole based DSSCs can be enhanced significantly by inserting a phenyl ring between the benzothiadiazole unit and the anchoring group.
Journal of the Turkish Chemical Society, Section A: Chemistry, 2018
In this study, we synthesized a novel benzimidazole-based Schiff base; (E)-4,4'methylenebis(2-((E)-(((1H-benzo[d]imidazol-2-yl)methyl)imino)methyl)phenol) (3) was synthesized by the condensation of 5,5'-methylenebis(2-hydroxybenzaldehyde) (1) and (1H-benzo[d]imidazol-2yl)methanamine.HCl salt (2). This Schiff base derivative was reported for the first time and fully characterized by common spectroscopic techniques. Absorption and fluorescence spectroscopy were recorded to determine the sensing ability of 3 towards metal ions. Selectivity to Zn 2+ ion among studied other cations was detected. The crystal structure of 2, C8H13Cl2N3O, has been determined by single crystal X-ray diffraction method. The crystal structure of the title compound, C8H11N3 2+ 2(Cl-)H2O, consists of an organic 1H-benzoimidazol-3-ium (C8H11N3 2+) cation, an inorganic 2(Cl-) anion and one water (H2O) molecule. In the cation of studied compound, C8H11N3 2+ , the benzimidazole ring is almost planar with a maximum deviation of-0.012 (3) Å. The molecule crystallized in the monoclinic structure and the space group P21/c. The crystalline stacking structure is stabilized by intramolecular N-H•••Cl, N-H•••O, the intermolecular N-H•••Cl hydrogen bond interactions connection the molecules into a two dimensional network and between anions and the water molecules. π-π interaction between benzimidazole rings [centroid-centroid lengths = 3.4642 (2) Å, 3.5309 (2) Å and 3.5527 (2) Å] may further stabilize the structure.
Spectral investigation of the intramolecular charge-transfer in some aminotriazole Schiff bases
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 2011
3-Amino-1,2,4-triazole Schiff bases were reported to contain intramolecular charge-transfer. The enhancing and depressing effects were remarkable as the substituent was changed from electron-donating to electron-withdrawing groups. The path of the resonating delocalization was reversed in the case of the p-NO2 group. To validate these results we effectively used Weinhold et al's natural bond orbital analysis to assess the UV and FT-IR spectrophotometric monitoring of the change reflected in this phenomenon when the substituent in the benzene ring is altered. The NBO analysis was simulated by ab inito computations at the HF/6-31G(d) level of theory, in order to properly detect any possible presence of a hydrogen bond association. The changes occurring in electron occupancies of double-centered bonds, antibonding orbitals and in lone-pair orbitals appraised the results, as did the s and p character listings of the two-centered bonds and the simultaneous changes occurring in the ge...
Dimethyl-2H-benzimidazole based small molecules as donor materials for organic photovoltaics
Solar Energy Materials and Solar Cells, 2011
Utilization of 2,2-dimethyl-2H-benzimidazole has received strong attention as the electron-deficient unit for the generation of electron donor material for organic photovoltaic cells (OPVs). This paper reports the first small organic molecules based on dimethyl-2H-benzimidazole, which can produce intramolecular charge transfer. Two soluble small organic molecules, MMM and OMO, with dimethyl-2H-benzimidazole unit were synthesized by Suzuki coupling reaction with Pd(0)-catalyst. The spectra of MMM and OMO in the solid thin films show absorption bands with maximum peaks at 374, 598 and 373, 588 nm, and the absorption onsets at 678 and 673 nm, corresponding to band gaps of 1.83 and 1.84 eV, respectively. The devices comprising MMM with PC61BM (1:3) showed a V OC of 0.66 V, a J SC of 2.03 mA/cm 2 , and a fill factor (FF) of 0.27, giving a power-conversion efficiency of 0.37%. Crown
Journal of Photochemistry and Photobiology A: Chemistry, 2004
The influence of benzimidazole additives on the performance of a bis(tetrabutylammonium)-cis-bis(thiocyanato)bis(2,2 -bipyridine-4carboxylic acid, 4 -carboxylate)ruthenium(II) dye-sensitized TiO 2 solar cell with an I − /I 3 − redox electrolyte in acetonitrile was investigated by measuring the current-voltage characteristics of more than 20 different benzimidazole derivatives under AM 1.5 (100 mW/cm 2 ). The benzimidazole additives tested had varying effects on the cell performance. Adding benzimidazole drastically enhanced the open-circuit photovoltage (V oc ) and the fill factor (ff), but reduced the short-circuit photocurrent density (J sc ) of the solar cell. In order to determine the reasons for the additive effects on cell performance the physical and chemical properties of the benzimidazoles were computationally calculated. Consequently, the greater the calculated partial charge of the nitrogen atoms in position 3 of the benzimidazole groups, the larger the V oc , but the smaller the J sc values. The V oc values also increased as the molecular size of the benzimidazole derivatives decreased. Moreover, the greater the absolute difference between the calculated dipole moment of the benzimidazole and acetonitrile, the larger the J sc value. These results suggest that these properties of the benzimidazoles influenced the extent of interaction between the TiO 2 electrode and electrolyte solvent, which changed the dye-sensitized solar cell performance.
Journal of Molecular Structure, 2003
The 1:1 molecular adducts derived from 2-aminobenzimidazole (ABZ) as a donor and either trinitrobenzene (TNB) or picric acid (PA) as an acceptor were synthesized. The spectroscopic studies of the two derivatives showed that ABZ -TNB (I) was a CT complex, while ABZ -PA (II) was an ion pair. The IR spectra of the complexes showed that the n(CyN) bands of donor moiety were shifted to higher frequencies while n asym (NO) bands of acceptors were shifted to lower wavenumbers. The UV -vis spectrum of ABZ -PA showed a visible band at 357 nm due to the picrate anion part of the molecule while the spectrum of ABZ -TNB exhibited a visible band due to charge transfer of pp* type of interaction. The crystal structures of the two derivatives were determined by single-crystal X-ray diffraction. The ABZ -TNB complex crystallizes in a triclinic cell (space group P 2 1), while the ABZ -PA adduct crystallizes in a monoclinic cell (space group P2 1 =c). The structures were determined by direct methods and refined to R ¼ 0.057 (I) and R ¼ 0.055 (II). q
Electrochimica Acta, 2014
Two new metal free sensitizers based on triphenylamine-benzothiadiazole were synthesized and used in dye sensitized solar cells (DSSCs). Electrochemical and optical properties of the dyes were studied by cyclic voltammetry, UV-vis absorption and fluorescence spectroscopy. A red shift was observed by the attachment of a thiophene (MZ-259) instead of a phenylene (MZ-255) bridge. The reverse effect was observed in the electrochemical properties because of the more electron-donating thiophene incorporated into the cyanoacrylic acid as an anchoring-acceptor unit in this system resulted in a higher LUMO level. The charge distribution of the dyes was also proved by DFT calculations using the Spartan10 program with the parameters of B3LYP and 6-31G** basis set. Finally the photovoltaic performances were investigated under standard AM 1.5 illumination with a power of 100 mW/cm 2 using an ionic liquid based electrolyte. The power conversion efficiencies, h, were increased from 3.16% to 3.81% by using thiophene instead of phenylene as a p-bridge unit.
Chemistry of Materials, 2011
A new series of electron-deficient molecules based on a central benzothiadiazole moiety flanked with vinylimides has been synthesized via Heck chemistry and used in solution-processed organic photovoltaics (OPV). Two new compounds, 4,7bis(4-(N-hexyl-phthalimide)vinyl)benzo[c]1,2,5-thiadiazole (PI-BT) and 4,7-bis(4-(N-hexylnaphthalimide)vinyl)benzo[c]1,2,5-thiadiazole (NI-BT), show significantly different behaviors in bulk heterojunction (BHJ) solar cells using poly(3-hexylthiophene) (P3HT) as the electron donor. Two-dimensional grazing incidence X-ray scattering (2D GIXS) experiments demonstrate that PI-BT shows significant crystallization in spin-coated thin films, whereas NI-BT does not. Density functional theory (DFT) calculations predict that while PI-BT maintains a planar structure in the ground state, steric interactions cause a twist in the NI-BT molecule, likely preventing significant crystallization. In BHJ solar cells with P3HT as donor, PI-BT devices achieved a large open-circuit voltage of 0.96 V and a maximum device powerconversion efficiency of 2.54%, whereas NI-BT containing devices only achieved 0.1% power-conversion efficiency.
Journal of Molecular Structure, 2019
The quantum chemical calculation of 1-[2-(2-hydroxy-3-methoxy-5-(4-chlorophenylazo) benzaldeneamino)ethyl]-3-methyl-3H-imidazole (CPBI) and 1-[2-(2-hydroxy-3-methoxy-5-(4fluorophenylazo)benzaldeneamino)ethyl]-3-methyl-3H-imidazole (FPBI) molecules were carried out. The Density Functional Theory (DFT) by the method B3LYP with the basis set of CC-pVDZ were performed. The Fourier Transform Infra Red spectrum and FT-Raman spectrum of the compound is recorded in the region 4000-400 and 4000-50 cm-1 respectively. The theoretical frequencies were scaled down and compared with experimental FT-IR and FT-Raman spectral values and they agree well. The Natural Bond analysis is performed to gauge the Lewis structure of the molecule. The first order hyperpolarizability values were calculated from the Non-Linear Optical (NLO) studies of the title molecule and compared with standard reference value of Urea. The molecular electrostatic potential surface is obtained and used to get the nucleophilic and electrophilic sites. The molecular docking study for title compound was carried out using Autodock Ver. 4.0. Light harvesting studies shows that both compounds are ideal choice for photosensitisers in photo-voltaic cells.