A push-pull compound with intramolecular charge transfer (ICT) characteristic, 6-Cl-2-StQ-NMe2, was synthesized in this work. The emission maxima of 6-Cl-2-StQ-NMe2 correlates excellently with the static polarity of the environment. In an aqueous solution, 6-Cl-2-StQ-NMe2 was observed to form an 'H type' aggregate in the ground state, but deaggregation occurred in the excited state. We find that 6-Cl-2-StQ-NMe2 can be used as a biosensor. Quantitative analysis showed that a linear relationship exists when bovine serum albumin (BSA) concentration is between 40 mu g/ml and 5000 mu g/ml. While monitoring the conformational change of BSA, the denaturation reaction was observed when the temperature exceeded 60 degrees C. (c) 2007 Elsevier B.V. All rights reserved.