Synthesis, molecular structure analyses and DFT studies on new asymmetrical azines based Schiff bases

Abstract

In this paper, we report the synthesis of new unsymmetrical azines Schiff bases. These compounds were prepared by condensation of hydrazine with different aldehydes and ketones to give (E) -2-hydroxynaphthalene-1-carbaldehyde [(1E) -2-thienylmethylene] hydrazone compound (I) and (Z) -2 -[(E) -1-(2-hydroxyphenyl) ethylidenehydrazin-1-ylidene] -1,2diphenylethanone compound (II). The method adopted consists in reacting the two different carbonyl compounds simultaneously in one step in a stepwise manner reported which is practical and cost-effective. The reaction with a minor modification in operating conditions proceeded efficiently and with excellent performance. The structure of each of the two compounds (I) and (II) was determined by the X-ray diffraction technique performed on single crystals. The asymmetric unity of the two molecules consists of one asymmetry-independent molecule. In addition, hydrogen bonds C-H ... π are observed in the compound (II). We then present a detailed DFT study based on B3LYP / 6-31G (d, p) geometric structures of compounds (I); (II) and another compound (III) also another asymmetric azine (Z) -2 -[(E) -2-benzylidenehydrazine-1-ylidene] -1,2diphenylethanone whose crystal structure is reported. The fundamental vibration wave numbers are calculated and a good agreement between the observed and calculated wave numbers is obtained. The study was extended to the HOMO-LUMO analysis to calculate the energy gap. The calculated HOMO and LUMO energy reveals that the charge is transferred into the molecule.

New bis hydrazone: Synthesis, X-ray crystal structure, DFT computations, conformational study and in silico study of the inhibition activity of SARS-CoV-2

“…Conversely, the calculated spectrum founded through TD-SCF CAM-B3LYP/6-31G (d,p) method for 3-Cl BHB compound showed a good resemblances in the shape and the band positions with the experimental UV-Vis spectrum in DMSO solvent. In which two broad peaks were detected by TD-DFT, the first is localized around 291 nm with Δλ= 8 nm shift, while the second peak at 401 nm due to HOMO→LUMO electron transfer which was in a good agreement with the n → π ∗ transition of the experimental UV-Vis spectrum (Δλ= 9 nm) [52] .

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Synthesis of dimethyl‐ and diphenylsilane‐based oligo(azine)s: Thermal, optical, electronic, and morphological properties

“…The absorption spectrum showed a broad absorption band at 347 nm (Figure 8a) attributed to π-π* and n-π* transitions of the aromatic rings and azine moieties. 49,50 Probably due to the short conjugation length π displayed by PAZ-4, a hypsochromic shift was evidenced regarding the previously reported azine-substituted oligo(p-phenylene-vinylene-azine)s or poly(thiophene)s with azine bridge. 4,8,50,51 In addition, the presence of TPS-core in the repetitive unit could be responsible for the absorption behavior of PAZ-4 through σ-π transitions of silicon atoms, interrupting the effective electronic conjugation along the main chain.…”

Palladium(0) Catalyzed Synthesis of (E)-4-Bromo-N-((3-bromothiophen-2-yl)methylene)-2-methylaniline Derivatives via Suzuki Cross-Coupling Reaction: An Exploration of Their Non-Linear Optical Properties, Reactivity and Structural Features

“…Conceptual DFT descriptors of reactivity may also be used in conjunction with the FMO energies to describe the reactivity of a molecule. The calculation of these electronic properties have been reported widely in the literature [ 23 , 24 , 25 , 26 , 27 ]. Ionization potential ( I ), electron affinity ( A ), chemical hardness ( ƞ ), and electronic chemical potential ( μ ) have been computed on the basis of Koopman’s theorem according to the formulas described previously by us [ 28 ].…”