The dimerization study of some cationic monomethine cyanine dyes by chemometrics method

Ahmadi, S., Deligeorgiev, T. G., Vasilev, A., Kubista, M. The dimerization study of some cationic monomethine cyanine dyes by chemometrics method. Russian Journal of Physical Chemistry, 86(13): 1974-1981, 2012. ISSN 0036-0244.

Abstract

The thermodynamics of the monomer-dimer equilibrium of five cationic monomethine cyanine dyes has been studied by means of UV-vis spectroscopy and advanced chemometrics methods. The dimerization constants were determined by studying the dependence of their absorption spectra on temperature in the range 20–75°C and were found to be: 1.91 × 10³, 1.53 × 10³, 6.81 × 10³, 5.18 × 10³, and 8.28 × 10³ dm³ mol⁻¹ for 1, 2, 3, 4, and 5 respectively. The absorption spectra of the monomer and dimer forms of the dyes were also determined, as well as the enthalpy and entropy of the dimerization.