The Applications Of Amine α-Cyanostilbene-modified Derivatives In Fluorescence Liquid Crystals And Environmental Sensing

Stilbene is a typical light-active π-conjugated molecule, which had been studied in many fields of modern chemistry, especially in optical functional materials. However, stilbene is just considered as model molecule in luminophore research and hard to meet the multiple demands in materials science due to its low quantum yield and short-waved fluorescence emission. As a kind of stilbene-derived molecule, cyanostilbene extended its conjugated structure and overcovered visible light region effectively. In terms of4-cyanostilbene and a-cyanostilbene, two kinds of representative stilbene derivatives, the latter can be modified easily because of more reactive chemically sites on the molecular structure. Hence, a-cyanostilbene can be modified into a wide variety of derivatives to meet the multifarious needs of materials. In this dissertation, two aspects of functionalized modifications were carried out on the basis of the a-cyanostilbene structure:(1) Oxygen alkyl chain located at the para-position of2-aromatic ring;(2) Amino located at the position opposite to the donor alkoxy group, a series of amino and oxygen alkyl functionalized a-cyanostilbene derivatives, namely HCA derivatives. Oxygen alkyl chain on the one hand, can effectively increase the fat-soluble ability of such derivatives, on the other hand, serve as a flexible side chain with the rigid a-cyanostilbene structure existed in the same structure, liquid crystal properties are expected. Amino modification makes this kind of derivatives form notable and short-distance hydrogen bonds by amino and cyano groups in the state of aggregation and strengthen the restricted "face-to-face" π-π accumulation effect caused by the significant steric hindrance and polarity of cyano. Meanwhile, easy protonated and functional features were endowed due to the alkaline and high reactivity of amino. On the basis of such molecular design ideas, the following several aspects of researches were conducted in this paper:(1) The synthesis, structure and photophysical behaviors of HCA derivatives:a series of simple and similar structural derivatives were synthesized through effective reduction reactions and nucleophilic substitutions. And their spatial and electronic structures were analyzed. In addition, the optical natures of such derivatives were studied systematically. The relations between the structure and properties were expounded explicitly.(2) The application of HCA derivatives in the fluorescent liquid crystal:liquid crystal is a kind of special compounds possess both anisotropic physical properties like the crystal and the fluidity like the liquid, and was widely researched and applied in the field of materials science. A comprehensive thermal stability, phase transition temperature and the properties of liquid crystal of such derivates were determined in this paper. And the thermal and liquid crystalline properties were summarized.(3) The application of HCA derivatives in chemical sensing:On the basis of the mastered structural characteristics and optical properties of the HCA derivatives and attributed to the easily protonation of amino groups, it was taken into the application to detect the high explosives (TNP).(4) Further function-modified HCA derivatives:HCA derivatives are easily modified to a wide variety of specific materials, such as Schiff base and amidothioureas compounds. A kind of a-cyanostilbene-derived Schiff base was synthesized and applied into the detection of Zn(II).