Single crystal to single crystal polymorphic phase transition of a silver nitrate 24-crown-8 complex and its pseudo-polymorphismElectronic supplementary information (ESI) available: Additional figures of packing, lists of Ag-O bond lengths, DSC analysis, figures with thermal ellipsoids (Figs. S9,10 and 11) and crystallographic data for 1, 1' and 2 are given. CCDC reference numbers 875797-875799. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c2ce25875g

A silver nitrate 24-crown-8 complex [Ag 4 (24-crown-8)(NO 3 ) 4 ] ( 1 ) was synthesized, showing a single crystal to single crystal polymorphic phase transition induced by temperature and leading to polymorph [Ag 4 (24-crown-8)(NO 3 ) 4 ] 1′ . When this complex ( 1 ) is exposed to humidity or directly crystallized from a water containing solvent, a pseudo polymorph [Ag 4 (24-crown-8)(NO 3 ) 4 (H 2 O) 2 ] ( 2 ) with two additional water molecules is obtained. When this pseudo polymorph is heated above 100° C, it may be transformed back into the first structure ( 1 ). Coordination compounds of silver nitrate with 24-crown-8 undergo reversible crystal-to-crystal phase transition on one hand, and, on the other hand, form hydrated species when exposed to humidity.