Enhanced emission of a pyridine-based luminogen by hydrogen-bonding to organic and polymeric phenols

Abstract

Fluorescent bis(pyridinylvinyl)anthracene (An2Py) with two pyridine terminals was synthesized and used to prepare miscible blends with hydroxyl-containing components (organic bisphenol A (BPA) and polymeric poly(vinyl phenol) (PVPh)) through the facile intermolecular hydrogen-bond (H-bond) interactions between the pyridine and the hydroxyl functions. Before blending, the solution of An2Py already emits appreciably due to its aggregation-induced emission enhancement (AIEE) behavior; after blending with the hydroxyl components, the fluorescence can be further intensified due to the restricted molecular rotation, which leads to the blockage of non-radiative decay channels, imposed by the H-bond interactions. The role of the H-bonding on the restricted molecular rotation of the An2Py/BPA (and the An2Py/PVPh) blends was characterized by solution 1H NMR and solid infrared spectroscopy. The effectiveness of the organic BPA and the polymeric PVP as molecular anchors to lock the free rotation of the An2Py luminogen were compared and discussed in this study.