| Budget Amount *help |
¥7,300,000 (Direct Cost: ¥7,300,000)
Fiscal Year 1990: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1989: ¥6,500,000 (Direct Cost: ¥6,500,000)
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| Research Abstract |
New compounds were prepared by various soft chemical methods such as ion exchange, intercalation, deintercalation and lithiation.
(1) Preparation of LiNbO_3-type compounds from CuMb_2O_6 (M=Nb, Ta).
Chemical insertion of lithium into CuNb_2O_6 and CuTa_2O_6 which have a distorted perovskite-type and the columbite-type structure, repectively, was carried out in the hexane solution of n-butyllithium at room temperature and 50^ﾟC, yielding new compounds, Li_<1-x>Cu_xMO_3, where part of Cu ion was extracted. When M=Ta, the product was found to have the LiNbO_3-type structure as a result of topotactic structural change on lithiation. On the other hand the framework of CuNb_2O_6 was intact on lithiation, but by heating at elevated temperatures in Ar atmosphere, the compounds transformed to the LiNbO_3 type structure. Although the transformation accompanies rearrangement of cations, it was considered to be a topochemical change, because the hexagonal close packed oxygen array was preserved in b
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oth structural types. The crystal structure of Li<@21-x<@>D2Cu<@D2x@>D2MO<@D23@>D2 was refined by the X-ray powder Rietveld method, revealing the arrangement of cation is very similar to that of ferroelectric LiMO<@D23@>D2.
(2) Intercalation of organic bases into layered compounds with controlled charge densities of the layer.
(H, Na)_xMo_2O_4・nH_2O and HTaWO_6・nH_2O were reacted with n-alkylamines, n-alkyldiamines and various organic bases having lower pKa than them at room temperature and 90^ﾟC for 3 days to 2 weeks in a sealed glass tube. In spite of difference in the charge density, the basal spacings of intercalation compounds from (H, Na) _x Mo_2O_4・nH_2O and H_xWOP_2O_7・nH_2O were similar for the same number of carbon atoms in the alkyl chains. The odd-even alternative change of the basal spacings was observed for n-alkyldiamine derivatives, indicating regular paraffin type structure in the interlayer spaces. The basal spacings of diamine deivatives indicated the gauche form of alkylchain for intercalation compounds of HTaWO_6・nH_2O and very declined arrangement of alkylchains to the layer for (H, Na) _xMo_4・nH_2O and H_xWOP_2O_7・nH_2O with low charge densities. The trans-cis transition of alkyl chain which is reported for some n-alkylamine derivatives of layered compounds was observed for the diamine derivatives of (H, Na)_xMo_2O_4・nH_2O.
The intercalation of quinoxaline with pKa of 0.56 indicates that HTaWO_6・nH _2O is stronger acid than layered titanates, niobates and molybdates. The characteristic feature of this compound is its capability of intercalation of rigid molecules such as p-aminoazobenzene which have been thought difficult to be intercalated. As indicated by the fact that isoquinoline derivative shows photochromisim on radiation of X-ray, HTaWO_6・nH_2O is a potential material for new functional material based on the interaction between molecules in the interlayer spaces or guest molecule and host as well as for catalyst. Less
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