Thiophene-cored 2,2-bis(methylol)propionic acid dendrimers for optical-power-limiting applications

The synthesis and characterization of dendron-coated 2,5-bis(phenylethynyl)thiophene chromophores are described. The dendrimers were grown divergently on the arylthiophene core with the versatile anhydride of 2,2-bis(methylol)propionic acid. The arylthiophene core was synthesized with Sonogashira coupling reactions. Structurally well-defined dendrimers up to the fourth generation were grown, as confirmed by size exclusion chromatography, NMR, and matrix-assisted laser desorption/ionization time-of-flight analysis. The different dendritic substitution did not influence the absorption spectra of the compounds in or near the visible region. Solutions of arylthiophenes had good transparency at wavelengths greater than 400 nm. The dendritic thiophenes exhibited an optical-power limit at the laser wavelength of 532 nm. However, the magnitude of the optical-power limit of these compounds was slightly lower than that of a nondendritic arylthiophene with n-pentyl substituents. (C) 2005 Wiley Periodicals, Inc.