A study of N,N '-dicarboxyalkylthiacarbocyanines as cyanine direactive dyes covalently bound to cellulose

The synthesis of N,N'-dicarboxyalkylthiacarbocyanines and their spectroscop ic properties before and fixation to microcrystalline cellulose are describ ed. Fixation yields were determined by FTIR spectroscopy, giving an alterna tive to the classical indirect spectroscopic method that uses the ratio of the areas of the absorption bands for cellulose and fixed dye. Diffuse refl ectance spectrometry was used to compare chemically bound dye on cellulose to physically adsorbed dye. These results, in tandem with laser induced flu orescence emission data, revealed the formation of aggregates and considera ble molecular distortion, the latter resulting from a decrease in molar abs orptivity compared to the case in which the dye is physically absorbed. (C) 2001 Elsevier Science Ltd. All rights reserved.