Hybrid (B3LYP) density functional calculations have been carried out to study the stability and electronic structure of adenine and its rare isomer Cu(II) complexes as well as their interaction with BN-doped fullerene. While the resulting two Cu(II)-tautomer complexes are almost isoenergetic complexes and exhibit very similar electronic structures which make their chemical identification difficult, we present evidence that BN modified fullerene could serve as a potentially viable nanoscale sensor to differentiate among these two Cu(II) complexes. The present results would suggest that the current conclusions are likely to hold for the adenine-thymine and adenine-rare-tautomer-thymine Cu(II) complexes as well. (C) 2012 Elsevier B.V. All rights reserved.