Molecular structure of tetraaqua adenosine 5'-triphosphate aluminium(III) complex: a study involving Raman spectroscopy, theoretical DFT and potentiometry.

The Alzheimer's disease is one of the most common neurodegenerative diseases that affect elderly population, due to the formation of ß-amyloid protein aggregate and several symptoms, especially progressive cognitive decline. The result is a decrease in capture of glucose by cells leading to obliteration, meddling in the Krebs cycle, the principal biochemical route to the energy production leading to a decline in the levels of adenosine 5'-triphosphate. Aluminium(III) is connected to Alzheimer's and its ion provides raise fluidity of the plasma membrane, decrease cell viability and aggregation of amyloid plaques. Studies reveal that AlATP complex promotes the formation of reactive fibrils of ß-amyloid protein and independent amyloidogenic peptides, suggesting the action of the complex as a chaperone in the role pathogenic process. In this research, one of complexes formed by Al(III) and adenosine 5'-triphosphate in aqueous solution is analyzed by potentiometry, Raman spectroscopy and ab initio calculations. The value of the logK(AlATP) found was 9.21±0.01 and adenosine 5'-triphosphate should act as a bidentate ligand in the complex. Raman spectroscopy and potentiometry indicate that donor atoms are the oxygen of the phosphate ß and the oxygen of the phosphate γ, the terminal phosphates. Computational calculations using Density Functional Theory, with hybrid functions B3LYP and 6-311++G(d,p) basis set regarding water solvent effects, have confirmed the results. Frontier molecular orbitals, electrostatic potential contour surface, electrostatic potential mapped and Mulliken charges of the title molecule were also investigated.

Novel zinc(II) and copper(II) complexes of a Mannich base derived from lawsone: Synthesis, single crystal X-ray analysis, ab initio density functional theory calculations and vibrational analysis.

Zinc(II) and copper(II) complexes of a tridentate Mannich base L1 derived from 2-hydroxy-1,4-naphthoquinone, pyridinecarboxyaldehyde and 2-aminomethylpyridine, [ZnL1Cl(2)]·H(2)O 1 and [CuL1Cl(2)]·2H(2)O 2, have been synthesized and fully characterized. The structure of complex 1 has been elucidated by a single crystal X-ray diffraction study: the zinc atom is pentacoordinate and the coordination geometry is a distorted square base pyramid, with a geometric structural parameter τ equal to 0.149. Vibrational spectroscopy and ab initio DFT calculations of both compounds have confirmed that the two complexes exhibit similar structures. Full assignment of the vibrational spectra was also supported by careful analysis of the distorted geometries generated by the normal modes.

FT-IR vibrational spectrum and DFT:B3LYP/6-31G and B3LYP/6-311G structure and vibrational analysis of glycinate-guanidoacetate nickel (II) complex: [Ni(Gly)(Gaa)].

The glycinate-guanidoacetate nickel (II) complex was synthesized and obtained as a crystalline powder. The characterization of this complex was performed by means of the experimental methods: CHN-O elemental analysis, atomic absorption spectrometry, thermo-gravimetric analysis and infrared spectrum. Density functional theory calculations, DFT:B3LYP/6-31G and B3LYP/6-311G, were performed for the determination of geometrical structure and vibrational assignment for the glycinate-guanidoacetate nickel (II) complex. A full discussion of the framework vibrational modes was done using as criteria the study of the distorted geometric structures generated for each one of the vibrational modes in the low energy region. As results of this research we have obtained and characterized a novel complex, glycinate-guanidoacetate nickel (II), [Ni(Gly)(Gaa)], and we deduced the most probable structure using the experimental data of the infrared spectrum in conjunction with the theoretical DFT procedures. The calculated DFT spectra in the high and low energy regions agree well with the observed ones.

Fourier transform infrared and Raman spectra, and AB initio calculations for cadmium(II)-cysteinate glycinate complex [Cd(Cys)(Gly)].

The cysteinate glycinate cadmium(II) complex was synthesized and structural analysis was carried out using the following methods: determination of the C, H, N, S and O contents, thermogravimetry, infrared and Raman spectra. The most probable structure for the complex at a minimum of energy was calculated by the density functional theory (DFT):B3LYP/3-21G quantum mechanical method. The infrared and Raman spectra were analyzed and bands assigned through the DFT procedures, the stabilization energy being equal to: E(RB+HF-LYP)= -6442.67784a.u. Features of the infrared and Raman spectra confirm theoretical structural prediction with respect to the metal-ligand bonds: Cd-O, Cd-S and Cd-N. Full assignment of the vibrational spectra was also supported by a carefully analysis of the distorted geometries generated by the normal modes.

Fourier transform infrared spectrum, vibrational analysis and structural determinations of the trans-bis(glycine)nickel(II) complex by means of the RHF/6-311G and DFT:B3LYP/6-31G and 6-311G methods.

The trans-bis(glycine)nickel(II) complex was synthesized, and the Fourier transform infrared spectra in the regions 4000-370 cm(-1) and 700-30 cm(-1) were measured. Band deconvolution analysis and the second derivative of the infrared spectrum were also performed. The determination of the geometrical structure in the trans position of the glycine ligands around Ni(II) for the trans-bis(glycine)nickel(II) complex as well as the vibrational assignment were assisted by RHF/6-311G and by Density Functional Theory calculations, DFT:B3LYP/6-31G and 6-311G basis sets. A full discussion of the framework vibrational modes was done using as criteria the geometry study of distorted structures generated for the vibrational modes. Incidentally, Normal Coordinate Analysis was carried out for the Ni(N)(2)(O)(2) structural fragment. The calculated DFT spectra in the high- and low-energy regions agree with the observed ones.

FT-IR vibrational spectrum and DFT:B3LYP/6-311G structure and vibrational analysis of bis-serinenickel(II) complex: [Ni(Ser)2].

The bis-serinenickel(II) complex was synthesized, and the Fourier-transforms infrared spectra in the regions 4000-370 and 700-30 cm(-1) was measured. The second derivative spectra and band deconvolution analysis was also obtained. Density functional theory calculations, DFT:B3LYP/6-311G, were performed for the determination of geometrical structure and vibrational assignment for the bis-serinenickel(II) complex. A full discussion of the framework vibrational modes was done using as criteria the geometry study of distorted structures generated for the vibrational modes. Incidentally, the normal coordinate analysis was carried out for the Ni(N)2(O)2 structural fragment. The calculated DFT spectra in the high and low energy regions agree well with the observed ones.

FT-IR vibrational spectrum and DFT:B3LYP/6-31G structure and vibrational analysis of guanidinoaceticserinenickel(II) complex: [Ni(GAA)(Ser)].

Vibrational assignment and structural determination for the guanidinoaceticserinenickel(II) complex have been made through DFT:B3LYP/6-31G calculations. A full discussion of the framework vibrational modes was done using as criteria the geometry study of distorted structures generated for the vibrational modes. Incidentally, the normal co-ordinate treatments have been made in order to clarify the assignments for the Ni(N)(2)(O)(2) structural fragment. The calculated DFT spectra in the high and low energy regions agree well with the observed ones.

Infrared spectrum, DFT: pBP86/DN** and NCA vibrational calculations of 2-methylthiosemicarbazide copper(II) nitrate [Cu(2MeTSC)2(NO3)2].

To elucidate tentative assignments of metal-ligand modes of thiosemicarbazide complexes, a structural study and a assignment of the normal vibrations of 2-methylthiosemicarbazide copper(II) nitrate, [Cu(2MeTSC)(2)(NO(3))(2)] have been done through the ab initio DFT: pBP86/DN** procedure, and through the normal coordinate analysis (NCA). In the vibrational calculations, the elongated CuONO(2) bonds of the nitrate groups were considered in the CS and CN tautomers of the complex. DFT calculations had revealed that the infrared spectra can be well interpreted through the CN tautomer, failing in the prediction of the -NO(2) group wavenumbers. A little difference stabilization energy for the tautomers were found: for the CN tautomer was E=-3487,36376a.u., and for the CS tautomer, E=-3473,93598a.u. The observed combination bands at 1763.0 and at 1754.0 cm(-1) are an indicative that the -NO(3)(-) groups acts as monodentate ligands. Calculations had confirmed the experimental assignment of the infrared spectrum.