Unique photophysical properties of 9-styryl-1,2-dihydropyrrolo[3,4-β]indolizin-3-one and its efficient synthesis via direct C–H activation

Abstract

A styryl Seoul-Fluor (SF) skeleton was rationally designed by introducing an olefin unit at the C-9 of 1,2-dihydropyrrolo[3,4-β]indolizin-3-one via regioselective direct C-H activation. We synthesized a series of styryl SF analogues, maintaining unique photophysical properties that can be systematically controlled by the electronic characteristics of the substituents, with an average bathochromic shift of 39 nm in emission maxima.

Rational Improvement of Molar Absorptivity Guided by Oscillator Strength: A Case Study with Furoindolizine‐Based Core Skeleton

“…[9] To test this hypothesis,starting from Seoul fluorophore (SF), an indolizine-based fluorescent core skeleton, [10] we envisioned the development of an ovel core skeleton with improved photophysical properties by the enhancement of its molar absorptivity,g uided by the computable oscillator strength value.W ep reviously observed am arginal enhancement of molar absorptivity when we tried the incorporation of naphthyl or styryl groups in SF (see Figure S1 in the Supporting Information). [11] Therefore,w ef ocused on the introduction of aheteroaromatic ring fused in indolizine core itself to extend the p-conjugated system, because the electronic nature of initial fluorophores can be significantly transformed by the inductive or resonance effects of the newly introduced heteroatom. [12] Of the potential heteroaromatic rings,wedecided to fuse af uran, after considering the remarkable molar absorptivity enhancement of BODIPY reported by Suzuki and co-workers.…”