Quinoline-based azo derivative assembly: Optical limiting property and enhancement mechanism

To further investigate the dependence of optical limiting properties on molecular structures, especially the strong intermolecular influence, such as the influences of hydrogen bond, dipole–dipole interaction and their synergetic effect on optical limiting properties, three polar D–π–A conjugated quinoline-based heterocyclic azo derivatives (3a, 3b and 3c) with different hydrogen-bond recognition abilities were designed and synthesized. Their structures and properties were characterized and evaluated by infrared spectroscopy, thermogravimetric analysis, and ultraviolet–visible spectrometry. The strengthening mechanism of optical limiting property was investigated in detail based on theoretical calculation and experimental results of molecular assembly induced by synergetic effect of hydrogen bond and dipole–dipole interaction. The results indicate that the optical limiting properties of these polar D–π–A conjugated optical materials were significantly affected by molecular structure, strong intermolecular interaction and their synergetic enhancement effect.