Synthesis of Blue Emissive Quaternary 9,9-Disubstituted N-Methyl-7-azaindole-Appended (Phenylethynyl)-fluorene Derivatives.

A highly functionalized 9,9-disubstituted (phenylethynyl)-fluorene-appended N-methyl-7-azaindole derivatives has been synthesized from various fluorene propargylic alcohols and substituted-7-azaindoles using BF3OEt2 as a catalyst. The scope of the reaction was demonstrated by selecting a range of fluorene propargylic alcohols and substituting 7-azaindoles. A plausible reaction mechanism for forming title compounds via propargylic carbocation is postulated. The synthetic transformation of the products has been demonstrated by the Suzuki coupling and Click reaction. The Suzuki coupled compounds 5a-5e were evaluated for photophysical properties such as absorption, solvatochromism, emission, and Stokes shift and found blue emissive in nature.