第一部分：1,8-

Abstract

Abstract This thesis consists of three parts. The first part is to develop metal ion chemosensors containing naphthyridine moiety; the second part is to design and synthesize water soluble carbohydrate receptors; the last part is to characterize the second-order nonlinear optical properties of thiophene conjugated heterocycles. Part I: Development of metal ion chemosensors containing naphthyridine moiety Up to now only a few chemosensors of heavy (transition) metal ions utilize fluorescence enhancement as the detection mechanism. Our research objective is to develop efficient fluorescent chemosensors and colorimetric chemosensors for transition metal ions (e.g. Hg2+ and Cu2+) with high sensitivity and selectivity. A series of intrinsic chemosensors p-CHEAN (1), p-BHEAN (2), m-CHEAN (3) and m-BHEAN (4) were thus designed and synthesized by the linkage of 1,8-naphthyridines as donors and bis(hydroxyethyl)aminophenyls as acceptors through triple bonds. The para-substituted chemosensors p-CHEAN and p-BHEAN displayed drastic color changes on addition of mercuric ion in an excellent selectivity in DMSO/H2O (1:1) solution. When these chemosensors bound with mercury ion, an intramolecular charge transfer occurred to account for the color changes. These colorimetric sensors provide a fast and easy method for the direct naked-eye sensing for mercuric ion. In comparison with p-CHEAN, the molecular sensor p-BHEAN of DAD type containing two arms with the bis(hydroxyethyl)amino donor groups at the para position exhibited the absorption band in the visible region, and offered two-stage changes p-BHEAN sensor to detect mercuric ion. On the other hand, the meta-substituted chemosensors m-CHEAN and m-BHEAN showed profound fluorescence enhancements on complexation with cupric ion in CH3CN. These fluorescence sensors were highly selective for Cu2+ ion in the presence of other metal ions (Ni2+, Co2+, Mg2+, Ca2+, Ba2+, Cd2+, Mn2+, and Pb2+). Part II: Design and synthesis of water soluble carbohydrate receptors The saccharide receptor contained the core structure of 1,8-naphthyridine which was linked via ethynyl bridges to two end groups of phenols. The BHPN molecule was synthesized,and found to bind strongly with various octyl glycosides via multiple hydrogen bondings in CH2Cl2. In order to develop effective chemosensors for saccharides in aqueous medium, we attempted to incorporate water-soluble moieties, derivatives with functional groups such as nitro group, carboxylic acid and sulfonic acid, to obtain the BHPN enhanced solubility in water. We have synthesized p-NO2-BHPN and m-CO2CH3-BHPN compounds successfully. However we encountered some problems in separation of the desired products due to their water-soluble properties. Part III: The second-order nonlinear optical properties of thiophene conjugated heterocycles The nonlinear optical properties of bicyclic thiophenes Y1-Y4 with