[Co2(ppca)2(H2O)(V4O12)0.5]:: A framework material exhibiting reversible shrinkage and expansion through a single-crystal-to-single-crystal transformation involving a change in the cobalt coordination environment

(Figure Presented) Shrinkage factor: The ligand ppca (4-(pyridin-4-yl) pyridine-2-carboxylic acid) has enabled the synthesis of a new 3D framework material, [{[Co2(ppca)2(H2O)(V 4O12)0.5]·3.62 H2O} n], which exhibits so-called dynamic structural changes". Temperature changes lead to the reversible removal of guest molecules and/or ligands (e.g. H2O) bound to the framework with a concomitant reversible structure change (see scheme). © 2005 Wiley-VCH Verlag GmbH & Co. KGaA."