In the present study, quantum chemical calculations were carried out to investigate the electronic structures and stabilities of adenine and its rare tautomer along with their Cu2+ complexes. Density Functional Theory (B3LYP method) was used in all calculations. The two Cu2+ complexes of adenine have almost similar energies and electronic structures; hence, their chemical differentiation is very difficult. For this purpose, interactions of these complexes with AlN modified fullerene (C-60) have been studied. Theoretical investigations reveal that AlN-doped C-60 may serve as a potentially viable nanoscale sensor for detection of the two Cu2+ complexes of adenine. (C) 2014 Elsevier Ltd. All rights reserved.