Naslov
Quantum chemical study of bis(L-threoninato)copper(II) and bis(L-allo-threoninato)copper(II) as isolated complexes

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

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

Izvornik
Abstract book of the Brijuni Conference: "Self organizing matter and emergence" / Bosanac, Slobodan Danko ; Cikota, Aleksandar ; Cikota, Stefan - Zagreb : Institut Ruđer Bošković, 2014, 33-33

ISBN
978-953-7941-01-7

Skup
The Brijuni Conference: "Self organizing matter and emergence"

Mjesto i datum
Brijuni, Hrvatska, 25.08.2014. - 30.08.2014

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
copper; L-threonine; L-allo-threonine; conformational analysis; isolated molecules; QM; DFT/B3LYP

Sažetak
Visible absorption and circular dichroism measurements of the title compounds, conducted in aqueous solution at neutral pH, showed that both ligands maintained their “glycine-like” configuration, i.e. they were bonded to Cu(II) via the amino nitrogen and carboxylato oxygen atoms, and formed bis-complexes.[1] This coordination mode is stable in the pH range 7 < pH < 9.[2] At pH ~ 9.4, a coordination change was observed to a “hydroxy-like” configuration, in which the copper(II) is coordinated via the amino nitrogen and hydroxy oxygen atoms.[2] However, the exact conformations of bis(L-threoninato)copper(II), Cu(L-Thr)2, and bis(L-allo-threoninato)copper(II), Cu(L-aThr)2, complexes in solution are unknown. The Cu(L-Thr)2 complex in trans glycinato-like coordination crystallised with one crystallisation water, [3] whereas the crystal structure of Cu(L-aThr)2 has not been reported. To examine the intramolecular effects due to the stereochemical differences on the molecular structures of the Thr-complexes, we completed conformational analyses of isolated Cu(L-Thr)2 and Cu(L-aThr)2 complexes with cis and trans glycinato-like configurations by the density functional theory (DFT) method and the unrestricted B3LYP functional with the LanL2DZ double-ζ basis set, to which a set of polarisation functions and diffuse functions were added. The analyses resulted in 53 minima of Cu(L-Thr)2, and 112 minima of Cu(L-aThr)2. The X-ray experimental Cu(L-Thr)2 conformer appeared unstable in vacuum. Among the most stable conformers in vacuum, an intramolecular hydrogen bond between the hydroxy group and the carboxyl oxygen atom is observed (Figure 1). The tendency to form this hydrogen bond is stronger in Cu(L-Thr)2 than Cu(L-aThr)2, which causes larger conformational flexibility of the latter system. [1] P. Grenouillet, R.-P. Martin, A. Rossi, M. Ptak, Biochim. Biophys. Acta 322 (1973) 185−194. [2] V. Noethig-Laslo, N. Paulić, Monatshefte für Chemie Chemical Monthly 128 (1997) 1101−1108. [3] A. C. Rizzi, O. E. Piro, E. E. Castellano, O. R. Nascimento, C. D. Brondino, Inorg. Chim. Acta 305 (2000) 19–25.

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Kemija

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