Multi-responsive Supramolecular Aggregates-photo Properties Investigation Of Bis-pyrene Derivatives

From1950s organic optoelectric materials have attracted extensive attentionsbecause of its unique properties and applications in many fields, such as organiclight-emitting device, sensor, biological imaging and memory chips. This articledescribes the syntheses, characterizations and properties of bis-pyrene derivatives andthe relationship between the molecular structure and photophysical properties wasinvestigated in detail as following:1. We have designed and synthesized the bis-pyrene derivatives, where the twopyrene units were connected by para-phthaloyl (p-BP) and meta-phthaloyl (m-BP)linkers. The compound p-BP in condense state does not respond to mechanicalshearing while the fluorescence emission of supramolecular aggregates of compoundm-BP in condensed state shows reversibly mechanochromic and vapochromicbehaviors. The dual-responsive phenomena were characterized by UV-Vis andfluorescence spectroscopy. Furthermore, the changes of supramolecular structures ofp-BP and m-BP were analyzed by powder X-ray diffractions (XRD) andtime-resolved fluorescence spectra, which indicate that the dual-responsivemechanism is related to their intermolecular interactions and packing modes. Thescanning electron microscope (SEM) was utilized to study the morphology of m-BPin different emission state. Finally, the multi-cycled information recording and erasingon the m-BP based film were demonstrated.2. Compound [6-(Pyrene-1-carbonyl)-pyridin-2-yl]-pyren-1-yl-methanone(m-BPy) was synthesized. The fluorescence emission of supramolecular aggregates ofcompound m-BPy in condensed state does not only shows reversiblymechanochromic and vapochromic behaviors, but also shows reversible fluorescenceswitch with acid/base treatment. Similarly, the multi-responsive phenomena werecharacterized by UV-vis and fluorescence spectroscopy. The changes ofsupramolecular structures of m-BPy were analyzed by XRD and time-resolvedfluorescence spectra. The SEM was utilized to study the morphology of m-BPy indifferent emission state. Finally, the relationship between the molecular structure andphotophysical properties was discussed.