Phosphorescent Decanuclear Bimetallic Pt 6 M 4 (M = Zn, Fe) Tetrahedral Cages.

Coordination-driven self-assembly delivers discrete, nanoscopic architectures that may preserve or enhance the physicochemical properties of their parent building blocks. Herein, we report the syntheses, characterization, and photophysical properties of two tetrahedral cages, [ZnII 4 L6 ](PF6 )8 (C1) and [FeII 4 L6 ](OTf)8 (C2), where L = PtII (PEt3 )2 (C≡C-bpy)2 (PEt3 = triethylphosphine; C≡C-bpy = 5-ethynyl-2,2'-bipyridine) and OTf = trifluoromethanesulfonate. C1 and C2 were assembled in isolated yields of 72% and 81% by treating 2 equiv of Zn(NO3 )2 ·6H2 O or Fe(OTf)2 with 3 equiv of L, respectively. Both cages were fully characterized by NMR, electrospray ionization mass spectrometry, and single-crystal X-ray diffraction (SCXRD). The local D3 symmetry at each polypyridyl metal node raises the possibility of a number of isomeric cages; however, only the homochiral enantiomers (ΔΔΔΔ and ΛΛΛΛ) are formed based on1 H NMR and SCXRD. C1 exhibits phosphorescence centered at 545 nm with a quantum yield of 10% in N2 -degassed acetonitrile at 25 °C. The quantum yield of C2 is significantly lower due to a nonradiative relaxation from5 MC (MC = metal-centered) states introduced by the FeII nodes.