Synthesis, single crystal structure, DNA binding and antioxidant properties of 5-(4-(dimethylamino)phenyl)-3-(thiophen-2-yl)-pyrazoline-1-carbothioamide

Abstract

Compound 3c (5-(4-(dimethylamino)phenyl)-3-(thiophen-2-yl)-pyrazoline-1-carbothioamide) was synthesized and characterized experimentally using UV-Vis, FT-IR, ESI-MS and NMR (1H and 13C) analysis. The compound shows strong antioxidant activity with IC50 value of 0.632±0.002 μg/mL. The compound crystallizes as a monoclinic system, P21/c centro-symmetric space group, Z = 8 and size of the corresponding unit cell: a = 11.7134(10) Å, b = 17.3334(15) Å, c = 16.9831(14) Å, α = 90˚, β = 108.038(2)˚, γ = 90˚. DNA binding measurements (UV-vis., fluorescence, cyclic voltammetry and competitive assay using ethidium bromide) of compounds showed intercalative mode of interaction. The binding constant (Kb), Gibbs free energy (ΔG) of compound 3c were found to be 1.3×105 M−1 and ‒67.17 KJmol−1, respectively. The calculated Ksv values at two different temperatures (298 and 303 K) are 3.02×103 and 2.16×103 M−1 respectively. To optimize molecular structure and compute wavenumbers of normal vibrational modes, B3LYP method and 6-311 ++ G (d, p) basis set were used. Hirshfeld surface analysis provides a thorough illustration of the intermolecular interactions on crystal surface, and fingerprint plots were discovered. Experimental bond lengths and bond angles corroborated well with the computational parameters. The GIAO approach was used to estimate 1H-NMR and 13C-NMR chemical shifts, and compared to experimental spectra. Electronic properties such as UV-Vis (in gas phase, ethanol and DMSO) were analyzed using TD-DFT method and the PCM solvent model, and results were compared to experimental UV-Vis spectra.