Zr derivatives of di- and tetra- phosphonic acids: structural variability studied by X-Ray powder diffraction data

Ferdinando Costantino, Riccardo Vivani

Dipartimento di Chimica, Via Elce di Sotto 8, 06123 Perugia, Italy

The recent metodologies developed for structural determination from X-ray powder diffraction, allowed us to solve the structures of many Zr phosphonates prepared in our laboratory.

Metal phosphonate based materials are today widely investigated from a fundamental point of view and also for their potential application in molecular and ionic recognition, catalysis, and solid state proton conductivity.

Reaction of zirconium (IV) fluorocomplexes with R-amino-N,N-bis methylphosphonic and diamino-N, N, N’, N’ - tetraphosphonic acids led to the formation of insoluble microcristalline solids with a great structural variability; solids with different connectivity and dimensionality were obtained by varying the nature of R groups, using different building blocks.

Common structural features in all the these solids were found, such as non-covalent interactions that played a crucial role in the connectivity, acting as “structure orienting factors”.

A class of structures of new Zr phosphonates solved “ab-initio” using conventional powder diffractometer will be presented, and the application of different methods for structure solution will be also discussed.

Fig.1 Structure of Zr 1,4-diaminocyclohexyl Fig.2 Structure of Zr 1,4-piperazine diphosphonate

tetraphosphonate

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