Preparation and spectroscopic characterization of a self-assembled monolayer of squarylium dye on gold

New squarylium dye-containing alkanethiol self-assembled monolayers (SAMs) on gold have been prepared. An unsymmetrical squarylium (SQ) dye for SAM has been synthesized from squaric acid. SQ dye monolayer was deposited on a gold surface by a stepwise method that includes covalent linkage of SQ dye to a cystamine monolayermodified gold. The molecular structure of a SAM of SQ dye was investigated using visible absorption and Fourier-transform reflection absorption spectra (RAS).