Design, Synthesis And Fluorescent Properties Of Divinyi Derivatives

In recent years, organic small molecular fluorescent materials have attracted intenseattention for their distinct properties, such as the easy synthesis and purification, theexcellent saturation and brightness of the emission, the easily control properties ofemission, and so on. Study of their application has been involved in many fields, such asorganic light-emitting diodes, fluorescence probes, organic field effect transistors, organicsolid lasers, sensors, memories, et al. Organic small molecular fluorescent materials have awide range of uses in pharmacology, environmental science, physiology, informationscience and many subjects. This paper presents two organic small molecular fluorescentmaterials based on divinyl anthracene and divinyl benzene conjugate structure. And studyon the relationship between the aggregating models and properties of BDTVA crystal.Besides, we also investigate the reason for the proton-triggered hypsochromicluminescence of DPD. The main research contents include follows:1. A new9,10-distyrylanthracene derivative BDTVA was designed and synthesized.Large single crystals were also prepared by physical vapor deposition. The study on theBDTVA crystal structure reveals that all the molecules in the crystal are arranged in thesame conformation and orientation, i.e. it is a uniaxially oriented crystal. This stackingmode is the most conducive to the optical properties, resulting in BDTVA crystalpossessing excellent waveguide and polarization performance. The loss coefficient is aslow as2.75cm1and the polarization contrast is as high as0.72, which is one of the bestresults in the relevant reports. In addition, BDTVA crystal also exhibits excellent amplifiedspontaneous emission properties. The threshold is265μJ/cm2, and the minimum peakwidth at half height and the gain coefficient are8nm and52cm1, respectively. Thesefeatures indicate that the BDTVA crystal may be potentially applied in the field of opticalwaveguides and organic solid-state lasers. 2. A new organic small molecular fluorescent material DPD containing piperidylgroups was designed and synthesized. The solution and powder of DPD both show a largehypsochromic shift upon the treatment of hydrochloric acid (HCl). We also investigate thereason for the proton-triggered hypsochromic emission. The theoretical calculations revelthat the switchable emission of DPD originated from the change of the distribution and thespatial arrangement of the frontier molecular orbitals. The nitrogen atoms in DPDmolecules have lone pair electrons and would bond with the hydrogen proton (H+) uponthe acid stimuli. This weakened the electron-donating ability of nitrogen atoms and madethe nitrogen atoms no longer involved in the π-conjugation, resulting in the decrease of theHOMO energy and an increased band gap contributing to the hypsochromic emission.Besides, the decrease of the crystalline degree and the different stacking modes of theDPD powder also contributed to the switchable emission between green and blue in theaggregates. Our study on the DPD not only provides a detailed insight into the origin ofthe hypsochromic shift, but also may contribute to the design and synthesis of novelfunctional chromophores with acid/alkali stimuli-response.