A new, highly selective and sensitive colorimetric chemosensor 1 for detection of Cu(2+) ions in aqueous solution was developed. Receptor 1 detected Cu(2+) ions by changing its color from colorless to yellow. Moreover, the Cu(2+)-sensitive compound was used as a colorimetric pH detector based on a color change due to 1-Cu(2+) complex formation identifiable by the naked eye.

A colorimetric assay for convenient detection of miRNA and RNase H activity was established in a homogeneous and label-free manner based on conformational and colorimetric changes of a polythiophene derivative (PMNT) in the duplex of DNA/PMNT and triplex of DNA/miRNA/PMNT.