Crystal growth of coordination polymers by gel diffusion

The use of gels or viscous materials as growth media for a wide range of compounds, including proteins, inorganic and organic compounds has already been reported in the literature. In the presence of a gel, sedimentation and convection currents are greatly suppressed and the mass transport of the molecules occurs mainly by diffusion. As a result, a lower nucleation density and a better crystal quality are usually observed.[1a] We report, here, new interesting phenomena observed in crystallization experiments ofcoordination compounds by using gels as diffusion media.[1b]. We have tested a variety of gel and resin-like systems as dispersion matrixes to crystallize a special class of polymeric and porous inorganic compound: the “coordination polymers”. We have used the gel technique to increase the size and quality of the crystals and as a mean to modify the crystal habit and get new crystalline species. [1b] In our experiments, we have observed some new phenomena of gel inclusion and morphological alteration of crystal surfaces. Diffraction, optical observations and interferometric measurements have been used for in situ monitoring the mass transport in the gelled/fluid phase during the crystallization process and for studying the crystallization kinetic. Funding from the Cariplo Foundation grant ‘‘2012‐0921” is gratefully acknowledged. [1] a) K.H. Henisch, Crystals in Gels and Liesegang Rings, Cambridge University Press, Cambridge, 1998; b) L. Carlucci, G. Ciani, J. M. Garcìa-Ruiz, M. Moret, D. M. Proserpio and S. Rizzato Cryst. Growth Des., 2009, 9(12), 5024-5034. [2] S.Rizzato et al., unpublished results.