A self-assembled squarylium dye monolayer for the detection of metal ions by surface plasmon resonances

Self-assembly of a squarylium dye containing an alkanethiol substituent on a gold surface is described. The self-assembled monolayers (SAMs) obtained were investigated by contact angle measurement and atomic force microscopy (AFM). Surface plasmon resonance (SPR) has been employed to investigate the interaction of the squarylium dye monolayer on gold with metal ions. A highly Cu2+ selective SPR sensing system was demonstrated with SAM for the squarylium dye on gold.