Influence of anthraquinone scaffold on E/Z isomer distribution of two thiosemicarbazone derivatives. 2D NMR and DFT studies

Condensed-phase relative Gibbs free energy and E/Z descriptors for 2-acetylthiophene and 2-acetylthiophene-N1-phenyl thiosemicarbazones

Thiosemicarbazones (TSCs) encompasses a class of compounds relevant in the pharmacological context. Their specific applicability varies in function of the appropriated chemical modification and their binding to different transition metals. In the present work, we apply current standards functionals, B3LYP and B97D, with triple zeta basis set quality, 6-311++G(d,p), to investigate the relative stability of the various possible spatial arrangements for 2-acetylthiophene and 2-acetylthiophene-N1-phenyl thiosemicarbazones, denoted ATTSC and ATTSC-Ph, respectively. The relative stability of neutral and deprotonated species at ethanol described by an implicit solvent model was investigated. For ATTSC, the relative Gibbs energy changed significantly upon deprotonation, and for ATTSC-Ph, a novel global minimum was identified. Based on the present study, deprotonation determines population in condensed-media. Such information, valid for ATTSC and ATTSC-Ph, can be crucial in studying other thiosemicarbazones.

Density functional theory study of structural and electronic properties of trans and cis structures of thiothixene as a nano-drug

The geometrical structure, electronic and optical properties, electronic absorption spectra, vibrational frequencies, natural charge distribution, MEP analysis and thermodynamic properties of the trans and cis structures of the drug thiothixene were investigated using density functional theory (DFT) and time-dependent DFT (TDDFT) methods with the B3LYP hybrid functional and 6-311 + G(d,p) basis set. The results of the calculations demonstrate that the cis structure of thiothixene has appropriate quantum properties that can act as an active medicine. The relative energies of trans and cis structures of thiothixene shows that the cis structure is more stable than the trans structure, with a small energy difference. TDDFT calculations show that the cis structure of thiothixene has the best absorption properties. The calculated NLO properties show that the NLO properties of the cis structure of thiothixene are higher than the trans structure, and the fact that the chemical hardness of the cis structure is lower than that of the trans structure that indicates that the reactivity and charge transfer of the cis isomer of thiothixene is higher than that of trans thiothixene. The molecular electrostatic potential (MEP) maps of both structures of thiothixene demonstrate that the oxygen atoms of the molecule are appropriate areas for electrophilic reactions. The vibrational frequencies of the two conformations of thiothixene demonstrate that both structures of thiothixene have almost similar modes of vibrations. The calculated thermodynamic parameters show that these quantities increase with enhancing temperature due to the enhancement of molecular vibrational intensities with temperature. Graphical abstract Trans/Cis isomerization of thiothixene drug.

Synthesis and biological evaluation of (acyl)hydrazones and thiosemicarbazones obtained via in situ condensation of iminium salts with nitrogen-containing nucleophiles

An unprecedented, highly convergent, high-yielding, one-pot synthesis of (acyl)hydrazones and thiosemicarbazones was carried out by the in situ condensation of isolable iminium chlorides of imidazolidin-2-(thio)one, tetrahydropyrimidin-2-thione and indole derivatives with nitrogen nucleophiles in the presence of a base. The developed reaction procedure is largely advantageous. It is highly parallelizable, no intermediates need to be isolated and minimal sample handling is required during the purification steps. Some relevant reaction parameters including reaction temperature and p[Formula: see text] of the base are discussed. NMR analysis was carried out to assess the stereochemistry of the obtained compounds. The stereochemical outcome of the reaction was found to be affected by the nature of the nitrogen-containing nucleophile being the majority of the derivatives isolated as single geometric isomers. The cytotoxicity and antiviral activities of the prepared compounds have been preliminary assessed. In cell-based screenings some of the derivatives proved to be cytotoxic at low micromolar concentrations and interesting anti-Reo-1 properties have been detected.