Abstract
FT-IR (4000-400 cm-1) and FT-Raman (3500-50 cm-1) spectra of (E)-N'(thiophen-2yl methylene)isonicotinohydrazide (TMINH) molecule was recorded in solid phase. The optimized geometry was calculated by B3LYP method with 6-311++G(d,p) basis set. The harmonic vibrational frequencies, infrared (IR) intensities and Raman scattering activities of the title compound were performed at same level of theory. The complete vibrational assignments were performed on the basis of the Total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The calculated first hyperpolarizability may be attractive for further studies on non-linear optical (NLO) properties of material. Stability of the molecule arising from hyperconjugative interaction and charge delocalization was analyzed using natural bond orbital (NBO) analysis. Highest occupied molecular orbital-Lowest unoccupied molecular orbital (HOMO-LUMO) energy gap explains the eventual charge transfer interactions taking place within the title molecule. A study on the electronic properties, such as excitation energies and wavelengths, were performed by time-dependent (TD-DFT) approach. Molecular electrostatic potential (MEP) provides the information on the electrophilic, nucleophilic and free radical prone reactive sites of the molecule. The thermodynamic properties such as heat capacity, entropy and enthalpy of the title compound were calculated at different temperatures in gas phase. 1H and 13C-NMR chemical shifts of the molecule were calculated using Gauge-independent atomic orbital (GIAO) method.To establish information about the interactions between human cytochrome protein and this novel compound theoretically, docking studies were carried out using Schrödinger software.
Highlights
The use of computational techniques is becoming increasingly common throughout all the various fields physics and chemistry and biology (Davidson, 2000)
The C1=C2, C3=C4, C1-S5 and C4-S5 calculated bond lengths are: 1.3676, 1.3779, 1.7316 & 1.7480 Å, in which the shortening of bond lengths (C3=C4& C4C5) are due to the attachment of hydrazone moiety at C4 atom and the calculated bond angle of C3-C4-S5 (110.85 ̊) is expected to be shorter than the C2-C1-S5 (112.27 ̊) bond angle. This trend is supported by our earlier study and find support from literature (Balachandran et al, 2014; Fleming et al, 2006)
The thiophene and hydrazone moieties of TMINH are co-planar as it is evident from the dihedral angles C3-C4-C9-N12/S5-C4-C9-N12 and C3-C4-C9-H10/S5-C4-C9-H10 are 179.12 ̊/-0.94 ̊ and -1.07 ̊/ 178.87 ̊, respectively and there is a good conjugation between p-orbitals of all atoms of hydrazone and thiophene moieties
Summary
The use of computational techniques is becoming increasingly common throughout all the various fields physics and chemistry and biology (Davidson, 2000). Thiophene derivatives have been reported to possess broad spectrum of biological properties including anti-inflammatory, analgesic, anti-depressant, anti-microbial and anti-convulsant activities (Molvi et al, 2007; SatheeshaRai et al, 2008; Ashalatha et al, 2007). A large number of heterocyclic carbohydrazides and their derivatives are reported to exhibit significant biological activities (Mansour et al, 2003; Metwally et al, 2006) and the carbohydrazide function represents an important pharmacophoric group in several classes of therapeutically useful substances (Mansour et al, 2003; Ghiglieri-Bertez et al, 1987). The NLO activity as well as the NBO study for TMINH molecule were performed to get more precise information about the hybridization and hydrogen bonding interaction of orbitals energies. Information about the size, shape, charge density distribution and site of chemical reactivity of TMINH were obtained by mapping electron density (ED) isosurface with MEP surfaces
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