GUEST ION RECOGNITION AND ENERGY MIGRATION TRANSFER IN A SUPRAMOLECULAR CUBIC ASSEMBLY OF TETRAKIS(RUBIDIUM 18-CROWN-6) TETRACHLOROMANGANATE(II) SPECIES

Competitive complexation of MCl4(2-) ligands (M = Mn, Fe, Co, Ni, Cu, Zn) to yield cubic F23 [(Rb18C6)4-{(MnCl4)1-x(MCl4)x}][TlCl4]2 complexes and the luminescence decay dynamics of the trapped [(Rb18C6)4MnCl4)2+ species were studied. The results reveal sensitivity of the supramolecular cubic lattice to variations in the thermodynamic stability of T(d) MCl4(2-) anions. Extensive multipolar interactions along the [(Rb18C6)4MnCl4]2+ sublattice are evident from facile donor-donor energy transfer. For [A18C6)4MnCl4] [TlCl4]2 (A = Rb, Tl), energy migration terminates in thermalized (almost-equal-to 50 kJ mol-1) exciton trapping by water molecules, presumably present in [(A18C6)4-MnCl][TlCl4]2.0.25H2O impurities. The thermal barrier is attributed to the dynamic reorientational motion of 18C6, which exhibits a similar thermal barrier. For[(Rb18C6)4{(MnCl4)1-x(CuCl4)x}][TlCl4]2 compounds, diffusive energy transfer from [(Rb18C6)4MnCl4]2+ to [(Rb18C6)4CuCl4]2+ traps dominates. Assuming dominant dipole-dipole interactions, the Cu2+-Mn2+ and Mn2+ Mn2+ coupling constants are 2.4 X 10(-50) M6 s-1 and 1.1 X 10(-50) M6 s-1, respectively.