Conjugated Thiophene-Fused Isatin Dyes through Intramolecular Direct Arylation

We
report on the design, synthesis, and properties of innovative,
planar, π-conjugated compounds in which a thiophene ring is
fused with the skeleton of the naturally occurring dye isatin. The
synthesis is achieved in high yields making use of an intramolecular
direct arylation reaction as the key step, making the overall process
potentially scalable. The synthetic sequence has been demonstrated
also for an isatin bearing fluorine substituents on the aromatic ring.
NMR and X-ray studies demonstrate the crosstalk occurring between
the fused, coplanar, and conjugated moieties, making these novel dyes
with a donor–acceptor character. Cyclic voltammetry and UV–vis
studies confirm very interesting HOMO–LUMO levels and energy
gaps for the new compounds.

本报告阐述了创新性平面π共轭化合物的设计、合成及其性质，其中噻吩环与天然存在的染料异喹啉骨架相融合。合成过程通过使用分子内直接芳基化反应作为关键步骤，以高收率实现，且整体流程具有潜在的规模化生产能力。该合成序列亦适用于在芳香环上带有氟取代基的异喹啉。核磁共振和X射线研究揭示了融合的、共平面的和共轭部分之间的串扰，这些新颖的染料具有供体-受体特性。循环伏安法和紫外-可见光谱研究证实了新化合物中非常有趣的HOMO-LUMO能级和能隙。