Some novel Y-shaped imidazole derivatives were developed for highly sensitive chemisensors for transition metal ions. A prominent fluorescence enhancement was found in the presence of transition metal ions such as Hg2+, Pb2+ and Cu2+ and it is due to the suppression of radiationless transitions from the n-pi* state in the chemisensors. The HOMO-LUMO energies, electric dipole moment (mu) and the first-hyperpolarizability (beta) values of the investigated molecule have been studied theoretically which reveal that the synthesized molecules have microscopic non-linear optical (NLO) behaviour with non-zero values. (C) 2011 Elsevier B.V. All rights reserved.