| Research Abstract |
1. Several complexes of rho-nitroaniline with inorganic acids such as HCl, HBr, HNO_3, and H_2SO_4 were synthesized and characterized by X-ray and elemental analyzes and IR and ^1H-NMR measurements. Among them, the rho-nitroaniline-hydrobromic acid crystal had a noncentrosymmetric structure and showed second harmonic generation (SHG).
2. Several complexes of rho-nitroaniline with metal chloride or metal oxides such as AlCl_3 and zeolite were synthesized and the SHG intensity was measured. Among them, the rho-nitroaniline-AlCl_3 compound showed the strongest SHG intensity (ca. 40 relative to urea). The intensity was changed with the rho-nitroaniline/AlCl_3 ratio, solvent, reaction time, content of water molecules, etc. The rho-nitroaniline-AlCl_3 compound did not show the catalytic activity for the formation of methanol from water and carbon dioxide.
3.Among SnO_2 and In_2O_3 elements modified by various metal oxides, CaO-loaded In_2O_3 element was found to show promising sensing properties to 2080 ppm CO_2 in air as high as 12.9, 9.9, and 6.6 in the presence of 0,1.1, and 1.8 vol% water vapor, respectively. The sensitivity to CO_2 depended on the operation temperature and the amounts of metal oxides loaded. In addition, the CO_2 sensing mechanism of La_2O_3-loaded SnO_2 was investigated by temperature programd desorption and it was suggested that the decrease in the resistance of the sensor results from the adsorption of beta-CO_2 and the desorption of O_- or O^<2-> to generate oxygen molecules and free electrons.
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