New fluorescence probes for biomolecules.

Steady state fluorescence measurements have been used for the investigation of interaction between the bovine serum albumin (BSA) and fluorescence probes: 3-hydroxy-2,4- bis[(3-methyl-1,3-benzoxazol-2(3H)-ylidene)methyl]cyclobut-2-en-1-one (SQ6), 3-hydroxy- 2,4-bis[(3-methyl-1,3-benzothiazol-2(3H)-ylidene)methyl]cyclobut-2-en-1-one (SQ7) and 3-hydroxy-2,4-bis[(1,3,3-trimethyl-1,3-dihydro-2H-indol-2-ylidene)methyl]cyclobut-2-en-1-one (SQ8). The binding constant between bovine serum albumin and squarine dyes has been determined by using both the Benesi-Hildebrand and Stern-Volmer equations. The negative value of free energy change indicates the existence of a spontaneous complexation process of BSA with squarine dyes.

Two-cationic 2-methylbenzothiazole derivatives as green light absorbed sensitizers in initiation of free radical polymerization.

-Methylpyridinium esters derivatives of 2-methylbenzothiazole hemicyanine dyes photoinitiators/photosensitizers derived from -propyl-3-[-2-methylbenzothiazolo]-4-pyridyno phenylacetic acid ester diiodide and -propyl-3-[-2-me]thylbenzothiazolo]-4-pyridino diphenylacetic acid ester diiodide were synthesized and proposed as new photoinitiators of polymerization of 2-ethyl-(2-hydroxymethyl)-1,3-propanediol triacrylate under argon laser exposure at 514 nm. These compounds exhibit a strong absorption around 520 nm. The dye/borate salt, dye/borate salt/-methoxypyridinium salt, dye/borate salt/diphenyliodonium salt, and dye/borate salt/1,3,5-triazine derivative combinations are very efficient in initiating of radical photopolymerization of triacrylate.

Hemicyanine dyes derived from 2,3,3-trimethyl-3H-indolium as candidates for non-covalent protein probes.

Non-covalent interaction of hemicyanine dyes, derivatives of 2,3,3-trimethyl-3H-indolium with bovine serum albumin has been studied by spectral method. For this purpose, three hemicyanine dyes containing N-(2-carboxyethyl)-2,3,3-trimethyl-3H-indolium moiety were synthesized and their UV/Vis and fluorescence spectra, aggregation, photostability and association with bovine serum albumin were studied. The hemicyanine dyes with 2-ethylcarboxylic group was found to interact with bovine serum albumin, which is probably due to negative charge on the dye molecule at the expense of the carboxylic group and the ability to form hydrogen bonds with albumin.