پديدآورندگان :
Ghanadzadeh Gilani Ali aggilani@gmail.com Department of Chemistry, Faculty of Science, University of Guilan, Rasht, Iran; , Poormohammadi Ahandani Zahra Department of Chemistry, Faculty of Science, University of Guilan, Rasht, Iran , Dezhampanah Hamid h.dpanah@guilan.ac.ir Department of Chemistry, Faculty of Science, University of Guilan, Rasht, Iran;
چكيده فارسي :
Dimerization thiazine dyes, azure B (AB) and toluidine blue O (TBO), in the presence of urea (U) and thiourea (TU) were studied at different additive concentrations at room temperatures. Due to structural similarity of the investigated dyes and the multiple properties of the additives, dimerization behavior of dyes in water with or without additive was studied in terms of monomer– dimer equilibrium. The spectral data for each dye were analyzed using DECOM Program. A reduction of the dimerization constant (Kd) for dyes in aqueous additive solutions into water was observed. It is found that in high concentrations of thiourea there is a competition between the dimer geometries (H-type and the J-type dimer). The nature and structure of the interacting pairs for these dyes were discussed using the exciton theory. The monomer and the dimer spectra are explained in term of molecular exciton model and the optical absorption parameters of the dyes were determined in different media.
