Insights of the Structure and Luminescence of Mn/Sn-Containing Crown-Ether Coordination Compounds.

Crown-ether coordination compounds with Mn and Sn as cations and 12-crown-4, 15-crown-5, and 18-crown-6 as ligands are synthesized. Their luminescence properties and quantum yields are compared and correlated with their structural features. Thus, MnI(15-crown-5) (), MnCl(15-crown-5) (), [Mn(12-crown-4)]N(Tf) (), SnI(15-crown-5) (), and SnI(18-crown-6) () are obtained by an ionic-liquid-based reaction of (: Mn, Sn; : Cl, I) and the respective crown ether. Whereas , , and exhibit a centric coordination of Mn/Sn by the crown ether, and show a sandwich-like coordination of the cation with two crown-ether molecules. All title compounds show visible emission, whereof , , and have good luminescence efficiencies with quantum yields of 47, 39, and 21%, respectively. These luminescence properties are compared with recently realized compounds such as MnCl(18-crown-6), MnI(18-crown-6), MnI(18-crown-6), or MnI(18-crown-6), which have significantly higher quantum yields of 98 and 100%. Based on a comparison of altogether nine crown-ether coordination compounds, the structural features can be correlated with the luminescence efficiency, which allows extraction of those conditions encouraging intense emission and high quantum yields.