Investigations into the Targeted Design of Solids: Hydrothermal Synthesis and Structures of One-, Two-, and Three-Dimensional Phases of the Oxo vanadium - Organodiphosphonate System

摘要

The recent expansion of the chemistry of the metal organopho.sphonate systems reflects their practical applications as catalysts, hosts in intercalation compounds, and protonic conductors. Vanadyl organophosphonates such as [VO(RPO)3)] centre dot xH_2O and [(VO)_2{(O_3P)_2CH_2}] centre dot 4H_2O, possess structurally well-defined internal void spaces and coordination sites which allow such material to intercalate alcohols by coordination of the substrate molecule to the vanadium sites of the V-P-O layer. When combined with readily modified organic substituents, the thermal stability and reactivity of transition metal oxide moieties, and the interplay of hy-drophihc and hydrophobic domains, such substrate-specific recognition and incipient coordinativc unsaturution ot the vanadium sites offers an approach to the design of hignly selective oxidation catalysts. We have sought to expand the chemistry of the V-O-RPO system by the introduction of vanous templates as structure-directing un!is. a methodology which results in a dramatic expansion of the range of material:, (with respect to structure and composition! of UK- analogous oxovanadium phosphate phases. Encouraged by our suc-cess in introducing progressively more radical modifications in the layered structures of V-O-RPO_3~(2-) phases by exploitation of appropriate templates, we have turned our atten-tion to the oxo inadium diphosnhonate system. V-O-[O_3P(CH_2)_nPO_3]~(4-) , where "engineering" of the material could be accomplished both bv introduction of different templates and by changes in the length of the diphosphonate -pace group R. Pursuing this strategy, one-, two- and pillared two- or three-dimensional phases. 1, 2. and 3 respectively, have been synthesized and structurally characterized.