Abstract:

Cyclooctatetrathiophenes (COThs) have attracted much attention for their unique "saddle-shaped" space structure, and interesting photoelectric properties. COThs have fourteen isomers and five of them have been reported up to now. COTh-1 exhibits aggregation induced emission properties. More importantly, the mechanism stems from its "saddle-shaped" structure. However, this compound can only be dissolved in few kinds of organic solvent such as tetrahydrofuran, and the low luminescence intensity limits their applications. Porous silica nanomaterials have the advantages of large specific surface area, large pore volume, tunable particle size, good biocompatibility, environmental friendliness and surface functionality. They can be used as good candidates for composing with organic materials. In this work, COTh-1 functionalized with 3-aminopropyltriethoxysilane, then COTh-silica hybrid nanomaterial were prepared by sol-gel method. Their structures, morphology and fluorescence properties were characterized carefully with Fourier transform infrared (FT-IR), scanning electron microscope (SEM) and fluorescence spectrum, respectively. FT-IR results show that COTh-1 molecules are linked on silica via covalent bonds. The morphology of hybrid particle is uniform sphere with size of 90~100 nm. More importantly, the emission intensity of the hybrid material is enhanced unambiguously compared with that of COTh-1. The possible reason is that COTh-1 molecules are fixed within the pores of silica and results in restriction of the intramolecular motions of COTh-1 molecules.

Key words: Cyclooctatetrathiophene, Silica, Hybrid Materials, Fluorescence properties