Synthesis and spectroscopic properties of 1,3,5-tris(arylalkynyl)-2,4,6-trimethoxybenzenes

A number of C₃-symetric 1,3,5-tris(arylalkynyl)-2,4,6-trimethoxybenzenes which carry electron withdrawing aryl substituents at the acetylenic periphery and donating methoxy groups on the central benzene ring are prepared via Sonogashira coupling. The utility of two different synthetic routes is evaluated as well as the effect of the nature of the aryl and ethynyl starting compounds in the coupling reaction. Finally, a correlation between the substitution pattern of the alkynyl compounds and their UV-vis and fluorescence spectroscopic properties is established.