Papers by Natasha Trendafilova
![Research paper thumbnail of Synthesis, X-ray structure, and DFT modeling of a new polymeric zinc(II) complex of 2-mercaptonicotinic acid (MntH), {[Zn(Mnt–Mnt)(en)]·H2O}n](https://a.academia-assets.com/images/blank-paper.jpg)
Monatshefte für Chemie - Chemical Monthly, 2019
Two zinc(II) complexes of 2-mercaptonicotinic acid (MntH), {[Zn(Mnt–Mnt)(en)]·H2O}n and [Zn(Mnt–M... more Two zinc(II) complexes of 2-mercaptonicotinic acid (MntH), {[Zn(Mnt–Mnt)(en)]·H2O}n and [Zn(Mnt–Mnt)(H2O)], were prepared by the reaction of ZnCl2 and MntH in the presence of ethylenediamine (en). They were characterized by elemental analysis, and IR, 1H, 13C NMR and UV–Vis spectroscopic studies. In the presence of en, the sulfur atoms of the MntH ligands were connected and formed a disulfide linkage in the Mnt–Mnt dimer. The single crystal X-ray diffraction analysis of {[Zn(Mnt–Mnt)(en)]·H2O}n complex revealed the polymer structure organization. Each zinc atom is five coordinated in distorted trigonal bipyramidal polyhedron by three oxygen atoms of two bridging Mnt–Mnt ligands and two nitrogen atoms of an en molecule. The vibrational modes, which characterized the carboxylic oxygen coordination of the Mnt–Mnt ligand to Zn(II), were determined by periodic DFT/PAW/PW91 calculations. Molecular structure modeling, vibrational spectra calculations, and natural bond orbital analysis of the monomer and dimer ligands as well as of the Zn(II) complexes were performed at the DFT/TDDFT/mPW1PW91 level to explain the available IR, NMR and UV–Vis spectroscopic data and to confirm the ligand coordination to the metal ion. The formation of disulfide Mnt–Mnt ligand in [Zn(Mnt–Mnt)(H2O)] was confirmed by the absence of the absorption band at 377 nm in the UV–Vis spectrum. The molecular modeling fragment of [Zn(Mnt–MntH)2(H2O)] suggested that the most probable structure is that consisting of five coordinated Zn(II) with one aqueous oxygen and four carboxylic oxygens of two bidentate bound Mnt–Mnt ligands in a polymeric structure.Graphical abstract
Spectrochimica Acta Part A: Molecular Spectroscopy
AIP Conference Proceedings
Journal of Theoretical and Computational Science
Photochemistry and photobiology, Jan 24, 2017
Semi-classical ab initio simulations of the absorption spectra of neutral and anionic p-hydroxybe... more Semi-classical ab initio simulations of the absorption spectra of neutral and anionic p-hydroxybenzylidene-2,3-dimethylimidazolinone (p-HBDI), a model chromophore of Green Fluorescent Protein (GFP) and of a positively charged neutral (N+)-HBDI chromophore model were performed in gas phase with the resolution-of-identity algebraic diagrammatic construction through second-order (RI-ADC(2)) method. The calculated absorption spectra in gas phase are composed of one band centered at 3.51 eV (HBDI), 2.50 eV (HBDI(-) ) and 3.02 eV ((N+)-HBDI) owing to the absorption of the first (1) ππ* transition. Band maxima are red-shifted by ~0.1 eV with respect to the corresponding vertical energies. The COSMO-RI-ADC(2) calculations of the first vertical excitation energy of HBDI, HBDI(-) and (N+)-HBDI forms in polar solution including microsolvation simulate the observed solvent red-shift for neutral HBDI and the solvent blue-shift of the HBDI(-) and (N+)-HBDI forms. The state-specific solvation appr...
Journal of Inorganic Biochemistry, 2016
Phosphor Sulfur Silicon, 1997
The conformational behaviour of H3CP(O)(CH2NH2)2 (mpbm) and its N,N′-coordinated Pt(II) chelate c... more The conformational behaviour of H3CP(O)(CH2NH2)2 (mpbm) and its N,N′-coordinated Pt(II) chelate chloro complex [Pt(mpbm)Cl2] has been studied by the Molecular Mechanics (MM) method. The calculation results for the complex have been compared with X-ray diffraction data. In the preferred mpbm conformations the C-N bonds were found to occupy trans, gauche-position with respect to C-CH3 and C-CH2 bonds. The chair-conformation with an equatorial methyl-group is the lowest energy conformation of [Pt(mpbm)Cl2] and the alternative chair-conformation is by 9 kJ mol less stable. Three possible pathways for the ring inversion of the complex are considered. The energy difference between the two MM-calculated chair-conformations of [Pt(mpbm)Cl2] is confirmed by Extended Huckel calculations.
Journal of Raman Spectroscopy, 2006
Spectrochimica Acta Part A: Molecular Spectroscopy, 1991
Journal of Inorganic Biochemistry, 2015
Silver(I) complexes of coumarin-based ligands and one of their phenanthroline (phen) adducts have... more Silver(I) complexes of coumarin-based ligands and one of their phenanthroline (phen) adducts have been prepared and characterized using microanalytical data, molar conductivity, IR, (1)H and (13)C NMR, UV-Vis, and atomic absorption (AAS) spectroscopies. The binding modes of the coumarin-based ligands and the most probable structure of their Ag(I) complexes were predicted by means of molecular modeling and calculations of their IR, NMR, and absorption spectra using density functional theory (DFT). The cytotoxicity of the compounds studied against human-derived hepatic carcinoma cells (Hep-G2) and a renal cancer cell line (A498) showed that the complexes were more cytotoxic than the clinically used chemotherapeutic, mitoxantrone. The compounds showed little interaction with DNA and also did not show nuclease activity but manifested excellent superoxide dismutase activity which may indicate that their mechanism of action is quite different to many metal-based therapeutics.
The Journal of Physical Chemistry A, 2015
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 1997
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, Jan 15, 2011
Novel Ni(II), Co(II), Zn(II) and Mn(II) complexes of coumarin-3-carboxylic acid (HCCA) were studi... more Novel Ni(II), Co(II), Zn(II) and Mn(II) complexes of coumarin-3-carboxylic acid (HCCA) were studied at experimental and theoretical levels. The complexes were characterised by elemental analyses, FT-IR, (1)H NMR, (13)C NMR and UV-Vis spectroscopy and by magnetic susceptibility measurements. The binding modes of the ligand and the spin states of the metal complexes were established by means of molecular modelling of the complexes studied and calculation of their IR, NMR and absorption spectra at DFT(TDDFT)/B3LYP level. The experimental and calculated data verified high spin Ni(II), Co(II) and Mn(II) complexes and a bidentate binding through the carboxylic oxygen atoms (CCA2). The model calculations predicted pseudo octahedral trans-[M(CCA2)(2)(H(2)O)(2)] structures for the Zn(II), Ni(II) and Co(II) complexes and a binuclear [Mn(2)(CCA2)(4)(H(2)O)(2)] structure. Experimental and calculated (1)H, (13)C NMR, IR and UV-Vis data were used to distinguish the two possible bidentate binding ...
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Papers by Natasha Trendafilova