White-light emission and near-infrared luminescent properties of lanthanide-aluminum 12-metallacrown-4 complexes formed with 2-iodobenzoate as the bridging ligand between the LnIII and AlIII ions

A series of 12-metallacrown-4 complexes, Ln III Na(2I-ben) 4 [12-MC Al(III)N(shi) -4], where Ln III = Gd III , Dy III , and Yb III , 2I-ben - is 2-iodobenzoate, and shi 3- is salicylhydroximate, LnAl 4 Na(2I-ben) 4 , showcases how the modular construction approach used to design these supramolecular coordination compounds allows the fine-tuning of their emission properties. The DyAl 4 Na(2I-ben) 4 and the benzoate (ben - ) analogue, DyAl 4 Na(ben) 4 , both display white-light emission properties with CIE (Commission Internationale d’Eclairage) 1931 color coordinates of (0.323, 0.368) and (0.320, 0.365), respectively, and correlated color temperature (CCT) values of 5865 and 5993 K, respectively. The CIE 1931 color coordinates are closer to the ideal values for white light (0.33, 0.33) than most analogous dysprosium-gallium 12-MC-4 complexes. In addition, the YbAl 4 Na(2I-ben) 4 compound emits in the near-infrared range with an Yb III -centered observed luminescence lifetime of 18.4(1) μs and a quantum yield, , value of 1.9(2)%. The combined utilization of ring Al III ions and 2-iodobenzoate demonstrates how the emission properties of this class of metallacrowns can be controlled through straightforward molecular modifications.