New indole-containing luminophores: convenient synthesis and aggregation-induced emission enhancement

A series of new indole-based luminophores (IIa-d) were conveniently synthesized through Ullmann reactions. They were well characterized by spectroscopic analyses and exhibited aggregation-induced emission enhancement (AIEE) properties. By simply changing the aromatic moieties in IIa-d, their maximum emission wavelengths could be well-tuned from 340 to 400 nm. The obtained experimental results, including the fluorescent behavior and the crystal structure in solid, demonstrated that the AIEE phenomena are caused by the restrictions of the intramolecular indolyl vibrational and rotational motions (around the Carbon-Nitrogen bonds). Copyright (C) 2008 John Wiley & Sons, Ltd.