engleski

ESTIMATION OF STABILITY CONSTANTS BY GRAPH-THEORETICAL MODELS. BINDING OF AMINO ACIDS TO COPPER(II) AND NICKEL(II) COMPLEXES WITH IMINODIACETATES AND PYRIDYL DERIVATIVES OF ASPARTIC ACID

Logarithms of stability constant K2, for binding of naturally occurring amino acids (A) to copper(II) mono-complexes (CuL) with iminodiacetic acid (IMDA) and its four N-substituted derivatives (MeIMDA, CyIMDA, t-BuIMDA, PhIMDA), were correlated to valence connectivity index of the 3rd order (3χ v) of CuL complexes. Good correlations were obtained only when it was assumed that bond between nitrogen and copper(II) does not take place for the mixed complexes of Cu(CyIMDA) and Cu(PhIMDA) with amino acids. Similar calculations were performed for binding of naturally occurring amino acids to copper(II) and nickel(II) complexes with N-pyridyl- or N-methylpyridyl-L-aspartic acid. Fair agreement with the experiment was obtained when it was assumed that pyridyl ring is not bonded to central atom for mixed complexes with amino acids having ability of side chain bonding to metal ion (threonine and phenylalanine). The best regressions gave respectively S.E.cv (log K2) of 0.18, 0.06, and 0.11 for Cu(IMDA), Cu(N-pyr-L-Asp), and Ni(N-pyr-L-Asp) complexes with amino acids.

Molecular graphs; Valence connectivity index; Regression models; Indicator variable

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