The descriptive power and utility of molecular connectivity terms deri
ved by a trial-and-error procedure from a medium-sized set of 8 molecu
lar connectivity indices has been tested on different properties of bi
ochemical compounds: amino acids, purines and pyrimidines. The trial-a
nd-error procedure is sometimes based on the entire set of molecular c
onnectivity indices, and sometimes on a subset composed solely of the
best molecular connectivity indices. The present paper reports a model
ing which encompasses the melting temperatures of natural amino acids,
the water solubility of a heterogeneous class of amino acids plus pur
ines and pyrimidines, and three different properties of the DNA-RNA ba
ses (U, T, A, G and C): singlet excitation energies Delta E-1 and Delt
a E-2, and molar absorption coefficient epsilon(260). The modeling is
in every case very satisfactory, both from the point of view of predic
tive power suid utility of the equations.