Synthesis and structural characterization of fluorinated thiosemicarbazones

A pH-responsive fluorescent sensor based on a new pyranoxanthylium salt

Stimuli-responsive pigments are very interesting for several technological applications, such as food and cosmetic colorants, color-based sensors and fluorescence probes, among others. In this work, the synthesis of a new xanthylium-derived pigment was developed and the chemical and photophysical properties in hydroalcoholic solution at different pH values were investigated by UV-Vis and fluorescence spectroscopy. The UV-Vis titration of 3,6,8-trihydroxy-11-methylpyranoxanthylium has shown four different colored chemical species (AH⁺, A, A^- and A^2-) in hydroalcoholic solution in a pH range between 1 and 12 with the thermodynamic acidic constants of pK_a1 = 4.80 ± 0.03, pK_a2 = 6.51 ± 0.05 and pK_a3 = 8.64 ± 0.01. Regarding fluorescence properties, this dye revealed an interesting pH-dependent emission behavior. In fact, the anionic quinoidal base A^- predominant at pH range between 5 and 9 should be mainly responsible for the pronounced fluorescence intensity observed at λ_ex 467 nm/λ_em 510 nm pair (maximum at pH 7.5). This set of new insights make this dye useful as a potential "off-on-off" pH-responsive fluorescent probe for biological applications. A pyranoxanthylium dye was developed and revealed a selective fluorescence emission between 5 < pH < 9, being maximum at pH 7.5, which make it very interesting as a pH-responsive "off-on-off" fluorescent probe for biomedical applications.

Synthesis, molecular modelling, FT-IR, Raman and NMR characterization, molecular docking and ADMET study of new nickel(II) complex with an N4-tetradentate thiosemicarbazone

A new nickel(II) complex was synthesized by using S-propyl-thiosemicarbazide and 2-amino-3,5-dibromobenzaldehyde. The complex, obtained by the template effect of nickel ions, was structurally analysed by experimental and theoretical vibrational spectroscopy, NMR and density functional theory (DFT) calculations. By using DFT/B3LYP method with 6-311++G(d, p) basis set, the most stable molecular structure of the title molecule was calculated. The fundamental vibrational wavenumbers, IR and Raman intensities for the optimized structure of the molecule under investigation were determined and compared with the experimental vibrational spectra. The vibrational assignment was achieved using the calculated potential energy distributions of the vibrational modes. Moreover, the molecular electrostatic potential (MEP), the highest occupied molecular orbital (HOMO) and the lowest occupied molecular orbital (LUMO) energies were calculated, Molecular docking of the molecule was carried out against DNA in order to identify the potential inhibitory action of the title compound. The findings suggested that the aforementioned compound has a strong binding affinity to interact with DNA residues DT8, DC9, DG12, DG16, DA17, and DA18 through the intermolecular hydrogen bonds. Also the performed in silico ADMET analysis was the prediction of the synthesized molecule's pharmacokinetic and toxicity profile expressing good oral drug like actions and non-toxic nature. The complex has been shown to have the possibility to become a model molecule for drug development processes.Communicated by Ramaswamy H. Sarma.

Crystal structure of (E)-2-(2-chloro-6-hydroxybenzylidene)hydrazine-1-carbothioamide, C8H8ClN3O4S

C8H8ClN3O4S, monoclinic, P21/c (no. 14), a = 12.662(2) Å, b = 5.2782(8) Å, c = 14.841(2) Å, β = 94.103(3)°, V = 989.3(3) Å3, Z = 4, R gt(F) = 0.0317, wR ref(F 2) = 0.1232, T = 293(2) K.

Crystal structure of (E)-2-((4-chlorophenyl)(phenyl)methylene)hydrazine-1-carbothioamide, C14H12ClN3S

C14H12ClN3S, monoclinic, C2/c (no. 15), a = 27.967(7) Å, b = 5.9290(13) Å, c = 19.698(5) Å, β = 118.122(3)°, V = 2880.6(11) Å3, Z = 8, R gt(F) = 0.0369, wR ref(F 2) = 0.1082, T = 293(2) K.

Crystal structure of 2-(bis(4-fluorophenyl)methylene)hydrazine-1-carbothioamide, C14H11F2N3S

C14H11F2N3S, monoclinic, C2/c (no. 15), a = 18.5399(19) Å, b = 9.5907(10) Å, c = 16.8149(17) Å, β = 111.307(2)°, V = 2785.5(5) Å3, Z = 8, R gt(F) = 0.0390, wR ref(F 2) = 0.1317, T = 293(2) K.