Interactions of N-acetyl-l-cysteine with metals (Ni2+, Cu2+ and Zn2+): an experimental and theoretical study (original) (raw)
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Quantum Computational Chemistry: Modeling and Calculation of S-Block Metal Ion Complexes
Density Functional Theory Calculations [Working Title]
The computational study of some s-block metal nitrophenolate complexes, [Ca(THEEN)(PIC)] + (1), [Ca(THPEN)(H 2 O) 2 ] 2+ (2), Ba(THPEN)(PIC) 2 (3) [Na(THPEN)] 2 2+ (4), [Sr(THPEN)(H 2 O) 2 ] 2 2+ (5) and [Ba(THPEN)(H 2 O) 2 ] 2 2+ (6) (where THEEN (N,N,N 0 ,N 0-Tetrakis(2-hydroxyethyl)ethylenediamine) and THPEN (N,N,N 0 ,N 0-Tetrakis(2-hydroxypropyl)ethylenediamine) are tetrapodal ligands and PIC À is 2,4,6-trinitrophenolate anion), is presented here using density functional theory (DFT) in its hybrid form B3LYP. The geometries of the title complexes are described by the quantum-chemical approach using input coordinates obtained from the previously synthesized and X-ray characterized diffraction data of [Ca(THEEN)(PIC)](PIC), [Ca(THPEN)(H 2 O) 2 ](PIC) 2 , Ba(THPEN)(PIC) 2 , [Na(THPEN)] 2 (PIC) 2 , [Sr(THPEN)(H 2 O) 2 ] 2 (DNP) 4 and [Ba(THPEN) (H 2 O) 2 ] 2 (DNP) 4 (where DNP is 3,5-dinitrophenolate). Only the primary coordination sphere of complexes (1-6) is optimized in the gaseous phase. Calculations of the energy gaps of frontier orbitals (HOMO-LUMO), 13 C-NMR shifts and vibrational bands are carried out using B3LYP/6-31 g + (d,p)/LANL2DZ level of theory. The calculated geometric and spectral parameters reproduced the experimental data with a well agreement.
Rasayan Journal of Chemistry
Ground state gas phase proton affinities, alkali metal cation (Li + , Na +) affinities and basicities of pyrrole, furan, thiophene and pyridine have been calculated computationally with the help of DFT /B3LYP method of calculation at hybrid triple zeta 6-311G(d,p) basis set level. Different binding sites of pyrrole, furan and thiophene for protonation are observed. Proton affinity (PA) value of Cα-H + complexes of pyrrole, furan and thiophene are found to be higher compared to Cβ-H + and X-H + complexes (X= N, O, S). In case of pyridine, protonation is found to occur at heteroatom (N) and the most stable protonated complex is formed. Results obtained in this calculation shows good agreement with the experimental values. Alkali metal cation (Li + , Na +) affinity and basicity of the same molecules have been calculated at the same level of theory. Pyridine exhibits the highest affinity for Li + and Na + cation. The electronic properties of the complexes indicate that polar co-valent sigma bond is formed by a proton with the binding site of the corresponding molecule whereas alkali metal cation (Li + ,Na +)-free molecule interactions are predominantly of an ion-dipole attraction and the ion-induced dipole interaction as well rather than a covalent interaction.Calculated proton and metal cation affinities are sought to be correlated with some of the computed system parameters like the calculated net charge on the binding atom of the free molecules and with the net charge on proton, Li + and Na + of the protonated, lithium and sodium complexes.
Journal of Inorganic Biochemistry, 2004
The question of the ðN ; SÞ vs. ðS; SÞ coordination mode on M Á (ACDA) 2 complexes (ACDA ¼ 2-aminocyclopentene-1-dithiocarboxylic acid, M ¼ Ni 2þ , Pd 2þ , Pt 2þ ) was assessed through an extensive ab initio study, using the hybrid B3LYP density functional approach. The ðS; SÞ coordination was found to be the most stable one, with an energy difference of ca. 50 kJ mol À1 relative to the ðN ; SÞ coordination mode. Detailed analysis of the ab initio results indicates that this preference is a result of the combined effect of geometry constraints and electron distribution within the complex.
The Journal of Physical Chemistry A, 2011
A set of benchmark results for the geometries, binding energies, and protonation affinities of 24 complexes of small organic ligands with Ca(II) is provided. The chosen level of theory is CCSD(T)/CBS obtained by means of a composite procedure. The performance of four density functionals, namely, PW91, PBE, B3LYP, and TPSS and several Pople-type basis sets, namely, 6-31G(d), 6-31+G(d), 6-31+G(2d,p) and 6-311+G(d) have been assessed. Additionally, the nature of the metal ligand bonding has been analyzed by means of the Symmetry Adapted Perturbation Theory (SAPT). We have found that the B3LYP hybrid functional, in conjunction with either the polarized double-ζ 6-31+G(2d,p) or the triple-ζ 6-311+ G(d) basis sets, yields the closest results compared to the benchmark data. The SAPT analysis stresses the importance of induction effects in the binding of these complexes and suggests that consideration of classical electrostatic contributions alone may not be reliable enough for the prediction of relative binding energies for Ca(II) complexes.
Oriental journal of chemistry, 2016
The 20-, 34-and 36-membered macrocyclic of bis (dithiodimine) Schiff base ligands, Bis-N,N'(dithiocarbonyl) terephthliden (L1), Bis-N,N'[1,3(o-aminophenylthio)-propane] terephthylidene (L2) and Bis-N,N-[1,4(o-amino phenylthio)-butane] terephthylidene (L3), have been prepared by a (2+2) condensation of terephthaldehyde with dithiooxamide or 1,3-bis-(o-aminophnylthio) propane,or1,4-bis-(o-aminophenylethio)-butane. Air stable dinuclear complexes of Co 2+ , Ni 2+ and Cu 2+ were obtained from reaction of metal salts with L1, L2 and L3 in tetrahydrofuran. Ligands consist of two S2N2 donor sites coordinated with the metal ions. Also, adducts of the cobalt complex with 1,4-phenelyene diamine was also presented. CHN elemental analysis, metal content, molar conductivity,magnetic measurements, proton nuclear magnetic resonance, UV-visible and infrared spectral studies have characterized the complexes and adducts. In addition to this, the DFT i.e. Density Functional Theoretical calculations has been used for supporting experimental data. This process used B3LYP functional method. It is the method which has been introduced due to Yang, Parr and Lee. This method is comprised of 3-parameter functional because of the presence of Axel Becke. It further incorporates the basis set of Los Alamos National Laboratory 2 double-zeta (LANL2DZ). Furthermore, the calculation associated with the molecule's vibrational frequencies was calculated with the help of optimized geometry. Tetrahedral and square planar geometry around Co 2+ ,Ni 2+ and Cu 2+ have been deduced on the basis of magnetic and spectra studies..
MOLCAS: a program package for computational chemistry
Computational Materials Science, 2003
The program system MOLCAS is a package for calculations of electronic and structural properties of molecular systems in gas, liquid, or solid phase. It contains a number of modern quantum chemical methods for studies of the electronic structure in ground and excited electronic states. A macromolecular environment can be modeled by a combination of quantum chemistry and molecular mechanics. It is further possible to describe a crystalline material using model potentials. Solvent effects can be treated using continuum models or by combining quantum chemical calculations with molecular dynamics or Monte-Carlo simulations.
Molecular mechanics calculations and metal ion recognition
Accounts of Chemical Research, 1990
An important idea in macrocyclic chemistry' and also in the chemistry of cryptates2 is size-match Selectivity, the idea that a metal ion will form its most stable complex with the member of a series of macrocycles where match between size of metal ion and macrocyclic cavity is closest. A classic example of size-match selectivity is seen in Figure 1, where formation constants3 of the crown ether 18-crown-6 (see Figure 2 for structures of ligands) are plotted for each metal ion as a function of ita ionic radius.4 The maximum in complex stability at K+ can be interpreted in terms of its ionic radius fitting the cavity in the crown ether most closely. Some criticism of this interpretation6 has been offered, since with smaller macrocycles such as 12-crown-4 the maximum in complex stability is still at the K+ ion, rather than shifting to smaller ions such as Li+. In general, however, size-match selectivity is widely acceptede as the most important factor in controlling metal ion selectivity in macrocyclic ligands.
Chemical Physics Letters, 1996
Our recent procedure of the unrestricted generalized transition state (uGTS) model for density functional calculations of core-electron binding energies has been applied to seven carbonyl and nitrosyl inorganic complexes: Fe(CO)5, Ni(CO)4, Mn(CO)4NO, Co(CO)3NO, Fe(CO)2(NO)2, Mn(NO)3CO and Cr(NO)4. The exchange-correlation potential is based on a combined functional of Becke's exchange (B88) and Perdew's correlation (P86). The cc-pVTZ basis set was used for the calculation of neutral molecules, while for the partial cation created in the uGTS approach we scaled the cc-pVTZ basis set using a procedure based on Clementi and Raimondi's rules for atomic screening. The average absolute deviation of the calculated core-electron binding energy from experiment is 0.28 eV.