Naslov
Conformational Analysis of Bis(L-asparaginato)copper(II) as an Isolated Complex

Autori
Marković, Marijana ; Ramek, Michael ; Sabolović, Jasmina

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
50th Symposium on Theoretical Chemistry STC 2014 Quantum Chemistry and Chemical Dynamics / González, Leticia - Beč, 2014, P34-P34

Skup
50th Symposium on Theoretical Chemistry STC 2014 Quantum Chemistry and Chemical Dynamics

Mjesto i datum
Beč, Austrija, 14.09.2014. - 18.09.2014

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
copper; asparagine; conformational analysis; isolated; QM; DFT/B3LYP

Sažetak
L-asparagine is an amino acid present in the exchangeable portion of copper(II) in human blood plasma, and it forms different complexes with copper(II). Moreover, the copper(II) complexes of amino acids, small peptides and other low-molecular-weight ligands are used as valuable model systems that mimic copper-binding sites existing in biological systems.[1] The title compound, Cu(L-Asn)2, has been studied during the past 40 years by various experimental methods, such as ultraviolet absorption and reflectance spectroscopy, potentiometric titration in aqueous solution, and magnetic and electron spin resonance measurements, X-ray absorption edge spectroscopy, and infrared and Raman vibrational spectra in the solid state.[2-4] The overall stability constants of Cu(L-Asn)2 were determined in water-dioxane mixtures, but more detail on the precise molecular geometries in solution is still lacking.[4] In the solid state, the Cu(L-Asn)2 crystallises as an anhydrous complex, with the copper(II) atom coordinated via the amino nitrogen and carboxylato oxygen atoms (i.e. the glycinato-like coordination mode) in a trans square-planar configuration. Two axially placed amide group oxygen atoms from adjacent molecules extend this to a tetragonally distorded octahedron.[5] A complete conformational analysis of Cu(L-Asn)2 complex in the gas phase with cis and trans glycinato-like coordination was performed using the density functional theory (DFT) method and the unrestricted B3LYP functional with the LanL2DZ double-ζ basis set, to which a set of polarization functions and diffuse functions was added. The goal of our study was to examine the intramolecular interactions in the resulting 42 minima of Cu(L-Asn)2. Among the most stable conformers in vacuum, strong intramolecular hydrogen bonds between the amide group and carboxyl oxygen and/or amino nitrogen atom are observed. The X-ray experimental Cu(L-Asn)2 conformer appears unstable in vacuum. The tendency to form hydrogen bonds is more pronounced in trans- than cis-Cu(L-Asn)2 owing to sterochemical reasons. [1] H. C. Freeman Adv. Protein Chem. 22 (1967) 257–424. [2] M. N. Srivastava et al. J. Inorg. Nucl. Chem., 38 (1976) 1897-1900. [3] E. J. Baran et al. Spectrochimica Acta Part A 66 (2007) 114–117. [4] A. Doğan et al. Analytical Biochem. 295 (2001) 237–239. [5] I. Vencato et al. Acta Cryst. E60 (2004) m1428-m1430

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Kemija

POVEZANOST RADA