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.
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.