Construction of Endo-Functionalized Two Dimensional Metallacycles via Coordination-Driven Self-Assembly

摘要

The synthesis of three endofunctionalized two-dimensional supramolecular metallacycles includingtwo [2 + 2] rhomboids (5 and 6) and a [3 + 3] hexagon (7) is reported. The resulting self-assembledsupramolecular structures, containing several nitrobenzyl moieties at their interior surface, have beenfully characterized by multinuclear NMR (31P and 111) and electrospray ionization mass spectro-metry. A significant C–H···0 hydrogen bonding between the nitrobenzyl acceptor and the edgemolecules of the supramolecular architecture is observed in the small rhomboid 5 and this interactiongradually decreases upon the enlargement of the resulting polygonal structures from a smallrhomboid 5 through a large rhomboid 6 to a hexagon 7. Molecular modeling with the MMFF forcefield gives a possible conformation of each self-assembly in different solvents and shows that thehydrophilic nitrobenzyl moiety prefers to be buried in the cavity of the resulting polygonal structuresin nonpolar solvents, thus forming hydrogen bonds with the peripheral component building units.