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Estimation of Stability Constants of Copper(II) Chelates with Amino Acids by Overlapping Spheres Method

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Naslov Estimation of Stability Constants of Copper(II) Chelates with Amino Acids by Overlapping Spheres Method
Procjena konstanti stabilnosti bakrovih(II) kelata s aminokiselinama metodom preklapanja kugli
 
Autor Raos, Nenad
 
Tema N-alkylated amino acids; molecular volumes
 
Opis The method of overlapping spheres (OS) was applied to the estimation of stability constants of mono- (log β110) and bis-complexes (log β120) of α-amino acids and their N-alkyl and N,Ndialkyl derivatives with copper(II). The central sphere, with a 0.3 or 0.4 nm radius, was placed at the central (Cu), equatorial (N) or apical (X) position of the coordination polyhedron. The overlapping volume of the central sphere and the van der Waals spheres of neighbouring atoms was calculated and correlated with the measured stability constants. The training set (N = 11) consisted of four naturally occurring amino acids and seven N-alkylated and N,N dialkylated glycines. It gave, upon linear regression of stability constants on the overlapping volume, correlation coefficients (r) of 0.944 and 0.895 for log β110 and log β120, respectively. The best regressions (r = 0.977–0.998) were obtained by taking into account only the complexes of N-alkylated glycine (N = 5) and placing the central sphere at the position of equatorial nitrogen atom(s). Using the regression functions derived from the training set, it was possible to estimate the measured stability constants with an error in the range 0.1–0.5 log β units.
Metoda preklapanja kugli (overlapping spheres, OS) primijenjena je za procjenu konstanti stabilnosti mono-kompleksa (log β110) i bis-kompleksa (log β120) α-aminokiselina i njihovih N-alikiliranih i N,N-dialikiliranih derivata s bakrom(II). Središnja kugla, radijusa 0,3 ili 0,4 nm, postavljena je u središnji (Cu), ekvatorijalni (N) ili apikalni (X) položaj koordinacijskoga poliedra. Izračunan je volumen preklapanja središnje kugle i van der Waalsovih kugli okolnih atoma te je zatim koreliran s izmjerenim konstantama stabilnosti. Temeljni skup (N = 11) sastojao se od četiri prirodne aminokiseline i sedam N-alikiliranih i N,N-dialkiliranih glicina. Linearnom regresijom konstanti stabilnosti prema volumenu preklapanja postignut je iz temeljnog skupa koeficijent korelacije (r) u iznosu od 0,944 za log β110 i 0,895 za log β120. Najbolje regresije (r = 0,977–0,998) dobivene su iz podataka samo za N-alkilirane glicine (N = 5), pri čemu se središnja kugla nalazila na ekvatorijalnome (dušikovome) atomu ili atomima. Iz regresijskih funkcija razvijenih na temeljnome skupu izračunane su konstante stabilnosti koje su se od izmjerenih vrijednosti razlikovale za 0,1 do 0,5 log β jedinice
 
Izdavač Croatian Chemical Society
 
Datum 2005-06-15
 
Vrsta resursa text
 
Format (na primjer PDF) pdf
 
Identifikator http://hrcak.srce.hr/8
http://hrcak.srce.hr/file/8
 
Izvor Croatica Chemica Acta (cca@chem.pmf.hr); Vol.78 No.2; ISSN 0011-1643 (Print); ISSN 1334-417X (Online)
 
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