Syntheses, spectral characterization, single crystal X-ray diffraction and DFT computational studies of novel thiazole derivatives

• A new series of thiazoles were synthesized and characterized by IR, NMR techniques.
• X-ray diffraction geometric parameters of 8 are compared with the theoretical values.
• Computed IR and NMR spectral data of 8 are compared with the experimental values.
• Influence of methoxy substituent on several molecular energies was also analyzed.

A novel thiazole (E)-1-((E)-2-methyl-3-phenylallylidene)-2-(4-phenylthiazole-2-yl)hydrazine 2 and its derivatives 3–8 were synthesized by cyclo condensation of (1E)-1-((E)-2-methyl-3-phenylallylidene)thiosemicarbazide 1 with substituted 2-bromoacetophenones. The synthesized thiazole derivatives were characterized by FT-IR, 1H NMR and 13C NMR analyses. For compound 8 single crystals X-ray diffraction analysis and density functional theory (DFT) calculation were carried out. The compound 8 crystallizes in the monoclinic space group P21/c with a = 7.4601 (3) Å, b = 5.7259 (2) Å, c = 41.0823 (13) Å, α = 90°, β = 91.715 (2)° and γ = 90°. The molecular geometrical parameters, frontier molecular orbital energies (HOMO, LUMO), their energy gap (ΔE), molecular electrostatic potential (MEP) and natural bond orbital (NBO) analysis of the compounds 2 and8 have been calculated by using DFT/B3LYP with 6-311G (d, p) level. In addition, IR frequencies, 1H and 13C NMR chemical shifts of compound 8 were also calculated by using DFT calculations at the same level basis set. The calculated geometrical parameters, IR frequencies, 1H and 13C NMR chemical shifts of the compound 8 were in good agreement with the observed single crystal-XRD data, IR, 1H and 13C NMR spectral values.

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