Phosphonate Modified Titanium Alkoxides:Intermediates in the Sol-Gel Processing of Novel Titania / Phosphonate Inorganic-Organic Hybrids

摘要

We are currently developing a 2-step sol-gel route to metal oxide / phosphonate hybrid materials,based on the non-hydrolytic condensation of a metal alkoxide with a phosphonic acid,followed by hydrolysis / condensation of the remaining alkoxy groups.Several molecular intermediates in this process were obtained by reaction of Ti(O~iPr)4 with phosphonic acids RPO3H2(R = Me,Ph,~tBu):[Ti4(O~iPr)2(~tBuPO3)]4(1),[Ti4(mu_3-O)(O~iPr)5(mu-O~iPr)3(PhPO3)3·DMSO(2),[Ti4(mu_3-O)(O~iPr)5(mu-O~iPr)3(MePO3)3]·DMSO(3),[Ti4(mu_3-0)(O~iPr)5(mu-O~iPr)3(~tBuPO3)3]DMSO(4),which were characterized by single crystal X-ray structure analysis and/or NMR spectroscopy.These compounds give information on the sol-gel chemistry in our process and are structural models for the final hybrid materials.In all cases the non-hydrolytic condensation is complete,and the phosphoryl oxygen is coordinated to a titanium atom.In addition,these clusters are soluble in common organic solvents and contain hydrolyzable alkoxy groups,which make them potential building blocks in the sol gel process.Accordingly,the use of cluster 2 as a single source precursor was investigated.