Solid‐State Luminescence and π‐Stacking in Crystalline Uranyl Dipicolinates

Crystal structure determinations on the hydrated forms of the complexes M2UO2(dipic)2, M = H, Rb, Cs, dipic = dipicolinate = pyridine‐2,6‐dicarboxylate, all of which show strong solid‐state luminescence from the uranyl centre, have as a common feature extended π‐stacking arrays of the dipicolinate ligands. Comparisons with related but non‐luminescent complexes indicate that these stacking arrays may be associated with efficient energy transfer from the dipicolinate “antennae” to the uranyl unit. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)