Photonic materials based on carborane cluster

Abstract

This thesis deals with photonic materials based on carborane clusters. This research provides various synthetic approaches to the development of novel photonic materials possessing enhanced response based on Lewis acidic properties of carborane cages. The design and synthesis of carborane clusters based new photonic materials with novel photonic properties will be first pursued and then the characteristics of such materials can be commonly applied to the photonic devices such as organic solar cells, organic light emitting diodes(OLEDs) and chemosensors. Firstly, p-terphenyl, biphenyl and fluorene based o-carborane compounds are designed and synthesized. All of the those compounds have demonstrated that introducing the o-carborane cages can gives rise to strong π-π* transition band assigned by aggregation-induced emission(AIE) in soild and doped film states at room temperature. These AIE bands appear fluorescence natures as the lifetime are measured with about one order nanoseconds. It is suggested from TD-DFT calculations that introducing the o-carborane cages induces the narrowing of the energy gap between the excited singlet state (S1) and the closest triplet state (T2), from which the facilitated S-T states mixing leads to a sufficiently nonradiative decay that represents non-emissive spectrum in THF solution states at room temperature in case of p-terphenyl and fluorene based o-carborane compounds. And then, the emissive PL spectrum in THF solution at 298K of the o-carborane substituted biphenyl indicates that the mixing between S1 and T2 state which requires substantially planar and rigid conformation state would appear to be easily impeded by free rotation of carborane and biphenyl moieties. Secondly, the carborane cages which possess high electron-withdrawing ability, high stability, and steric protection will be combined with the triarylborane sensors so as to increase both the Lewis acidity and the anion selectivity of boron center. A triarylborane be...