engleski

Synthetic strategies for delivering targeted supramolecular topologies of crystalline metal- containing solids

Practical crystal engineering, as a bottom-up approach for building-up functional materials, is transitioning from fundamental explorations to more targeted applications. This is illustrated by the fact that numerous productive strategies for non-covalent synthesis of organic solids-state systems have been reported.[1] In contrast, reliable synthetic protocols for the assembly of metal-containing systems, especially those that employ a combination of coordinate-covalent and relatively weak and readily reversible hydrogen and/or halogen bonds, have not received anywhere near the same attention. To develop robust synthetic protocols for assembling metal-organic crystalline solids in a preconceived manner, we have focused our attention on several functionalities that are known to form robust and reliable supramolecular synthons in organic surrounding and examine their potential transferability to metal-organic systems. Coordination complexes often present additional challenges to the supramolecular chemist as they frequently contain functionalities and binding sites that can interfere with the intended crystal engineering strategy. Here, we have carried out a systematic structural study of a number of classes of metal(II) complexes with pyridine-type and charge-balancing ligands, and rationalized their supramolecular behaviour against a back-drop of molecular electrostatic potential (MEP) surface values. Based on our extensive experimental data, [2-5] we are able to address several questions of critical importance to the successful assembly of metal-containing systems: (a) Under what conditions can we simply transfer specific synthons from organic to metal-organic solid-state systems? (b) Can a simplified electrostatic view of non-covalent interactions and the results from the calculated MEP values be used to direct and rationalize supramolecular synthesis? and (c) How can we derive supramolecular synthetic protocols in much the same way as classical synthesis is systematically altered and refined in response to product yields?

hydrogen bond ; halogen bonds ; supramolecular synthesis

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