Crystalline-State cis-to-trans Transformation of a Two-Dimensional Spin-Crossover System

Supramolecular structural transformations involving coordination polymers (CP) in the crystalline state form an promising body of research, not only because they can provide direct proof which helps understand topochemical reactions, but also due to the accompanied modulation of physical/ chemical properties, such as magnetic, optical, and chiral behavior, which helps gain insights into the correlation between structural and magnetic properties. In contrast to the relatively common crystal transformation triggered solely by guest removal/inclusion, transformation involving drastic reorganization of the network connectivity, such as change of interpenetration/dimensionality and special atom movements, is more likely to provide new phases with totally different properties thus is more fascinating. However, rare examples have been reported involving such transformations, mainly due to the difficulty to maintain crystallinity after a large structural rearrangement, and thus further investigations on the subsequent physical/chemical property changes are more scarce. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.