A Chiral Molecular Square with Metallo-Corners for Enantioselective Sensing

A family of chiral molecular squares based on fac-Re(CO)3Cl metallocorners and enantiopure atropisomeric bipyridine bridging ligands (L1-4) have been synthesized in high yields by refluxing ClRe(CO)5 and L1-4 in 1:1 molar ratio. These novel chiral metallocycles have been characterized by 1H and 13C{1H} NMR, UV-vis, luminescence, and circular dichroism (CD) spectroscopies, FAB mass spectrometry, and microanalysis. Molecular square 4 which contains four 1,1'-bi-2-naphthol functionalities exhibits interesting enantioselective luminescence quenching by 2-amino-1-propanol. This research illustrates the potential of generating novel functional materials based on supramolecular chemistry.