Tsvetan Zahariev

Tsvetan Zahariev
Bulgarian Academy of Sciences | BAS · Institute of General and Inorganic Chemistry

PhD, Theoretical Chemistry - Quantum Chemistry

About

20
Publications
5,341
Reads
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85
Citations
Citations since 2016
13 Research Items
83 Citations
20162017201820192020202120220510152025
20162017201820192020202120220510152025
20162017201820192020202120220510152025
20162017201820192020202120220510152025
Additional affiliations
April 2016 - October 2019
Bulgarian Academy of Sciences
Position
  • Researcher
March 2014 - June 2014
Sofia University "St. Kliment Ohridski"
Position
  • PhD Student
Description
  • Lab exercises in Physical Chemistry for students in the B.Sc. program in “Ecochemistry”.
October 2013 - June 2014
National High School of Mathematics and Natural Sciences
Position
  • Lecturer
Description
  • Training course in Advanced Analytical Chemistry
Education
January 2012 - January 2016
Sofia University "St. Kliment Ohridski"
Field of study
  • Theoretical Chemistry
October 2010 - October 2011
Sofia University "St. Kliment Ohridski"
Field of study
  • Computational Chemistry
October 2006 - October 2010

Publications

Publications (20)
Article
The complete photophysical process, from absorption in the UV region, excited state energy transitions, ligand → Eu(III) energy transfer to luminescence of Eu(phen)2(NO3)3 in Vis region, is elucidated by means of two theoretical approaches and in close relation to the experiment. The energy diagram, S1 and T1 excited state character and the concurr...
Article
Combined experimental (X-ray, IR and Raman) and theoretical (periodic DFT/PAW-PW91) studies have been performed for thorough understanding of the structure, hydrogen bonding and vibrational properties for three alkylenediammonium hexachlorostannates with the general formula: [NH3(CH2)nNH3]SnCl6 (n = 3, 4, 5). X-ray diffraction analysis indicated tw...
Article
Excited state energy level diagrams of coumarin-3-carboxylic acid (HCCA) chromophore, Eu(CCA)Cl2(H2O)2 (1), Eu(CCA)2Cl(H2O)2 (2), Eu(CCA)3(H2O)3 (3), Tb(CCA)2Cl(H2O) (4) and Tb(CCA)2(NO3)(H2O) (5) in gas phase and polar solution have been calculated by means of DFT/TDDFT/ωB97XD methods. Based on these results, the ability of CCA to sensitize Eu(III...
Article
The photophysical processes, from excitation in the UV range, energy migration pathways to luminescence of Tb (phen) 2 (NO 3) 3 complex in the Vis region have been studied by theoretical approaches and spectroscopic measurements. The UV-Vis absorption, diffuse reflectance, excitation and luminescence spectra indicated that the ligand 1,10-phenanthr...
Article
The effect of SiO2-based substrates on the red luminescence of Eu(Phen)2X3 complexes (X ≡ Cl⁻, NO3–) is studied by means of semiempirical methods (Sparkle/AM1; INDO/S-CIS) and the simplified TDDFT method of Grimme. Structure, spectroscopic properties and energy diagrams are reproduced, and the most concurrent energy transitions are determined. Liga...
Article
Three Mg(II) perrhenate complexes were synthesized in aqueous solution and the crystal structures of neutral Mg(H2O)2(ReO4)2 (1) and two novel ionic complexes with urea (U, OC(NH2)2), [Mg(H2O)2(U)4](ReO4)2 (2) and [Mg(U)6](ReO4)2 (3) were determined by single crystal X-ray diffraction. The compounds were examined by DTA-TG-MS analysis, FT-infrared...
Article
A perspective hybrid material, NH3(CH2)7NH3BiCl5, was extensively characterized by structural, DSC, spectroscopic (FT-IR, FT-Raman, and UV-fluorescence) and theoretical (periodic DFT/GGA/PBE) methods. The structural features, noncovalent interactions between molecules in the crystal and electronic structure were examined and discussed in relation t...
Article
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...
Article
A novel dinuclear copper(I) complex, {[Cu2(Mnt)2(PPh3)2Cl2].2H2O.CH3CN}2 (1) (Mnt = Mercaptonicotinic acid, PPh3 = triphenylphosphine) was prepared and its structure was determined by X-ray crystallography. The complex 1 consists of two dinuclear molecules and in each molecule, the two copper atoms are bridged by S atoms of N-protonated mercaptonic...
Article
Experimental and periodic DFT studies of the structural and vibrational (infrared and Raman) properties of two alkylenediammonium hexafluorosilicate compounds, NH3(CH2)4NH3SiF6 (1) and NH3(CH2)6NH3SiF6 (2), have been performed in crystal phase, where three-dimensional N-H···F hydrogen bonds (HB) network was formed. The analysis of the vibrational s...
Article
Full-text available
The review is aimed at introducing the readers to the theoretical methods used in free energy estimations from molecular simulations data. The theoretical background of each approach is presented in detail. The main advantages and disadvantages of the methods are discussed, as well as the algorithms used for quantifying estimation errors of the the...
Article
Fully atomistic molecular dynamics simulations were performed on liquid n-pentane, n-hexane, and n-heptane to derive an atomistic model for middle-chain-length alkanes. All simulations were based on existing molecular-mechanical parameters for alkanes. The computational protocol was optimized, for example, in terms of thermo- and barostat, to repro...
Conference Paper
Full-text available
The current study is focused on creating an adequate atomistic model of liquid oil based on the simplest pure n-alkanes, namely, pentane, hexane and heptane. Molecular dynamics simulations of the liquid hydrocarbons at standard pressure are run using the AMBER99 potential functions. A set of structural and thermodynamic properties are estimated and...
Article
Olygo(ethylene glycol) alkyl ethers – C x E y are well known for their high surface activity and rich phase behavior. These substances exhibit some unusual aggregation characteristics in aqueous solution even at concentrations well below CMC attributed to the formation of pre-aggregates of small size, e.g., dimers. To verify this, a series of C 12...

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Projects

Project (1)
Project
The aim of this project is through experimental and quantum chemical studies to examine the elementary processes, which underlie the functionality of the luminescent materials applied as UV-sensors, optical filters and labels for chemical and biological purposes in hybrid complexes. The processes of energy transfer and emission taking place in hybrid molecules and sol-gel systems containing the above mentioned complexes will be examined in the proposed project. In the frame of the project, a novel method for preparation of hybrid sol-gel materials will be applied. It is based on the functionalization with 1,10 - phenanthroline of doped with Eu3+ sol-gel ZrO2-SiO2 microcomposites as well as on the granulated nanoporous aerogel materials, consisting of SiO2. Sol-gel materials, which contain complexes of lanthanide ions and organic ligands are brightly luminescent hybrid systems.