Structure property relationships of amino acids and some dipeptides.

A molecular connectivity model of the crystal densities and specific rotations of some natural amino acids and of the longitudinal relaxation rates of some natural amino acids and cyclic dipeptides is presented. While crystal densities and relaxation rates are better described by a set of three valence molecular connectivity indices {D (v),(0) X (v),(1) X (v)}, specific rotations are better described by a set of two simple molecular connectivity indices {(1) X,(0) X}. Relaxation rates are, also, well described by the simple molecular connectivity {D,(1) X} index set. Use of orthogonal indices, derived from the corresponding ordinary indices shows, in the case of specific rotations, the possibility to condense the information by the aid of a single high quality descriptor underlining, thus, the versatility of these indices and also their dependence on the orthogonalisation process.