Unusual luminescence spectra and decay dynamics in crystalline supramolecular [(A18C6)(4)MBr4][TlBr4](2) (A = Rb, K; M = 3d element) complexes

Luminescence and electronic energy transport characteristics of supramolecular cubic F23 [(A18C6)(4)MnBr4][TlBr4](2) complexes (A = Rb, 1; A = K, 2) were studied with the expectation that MnBr42- ions would be effective luminescent probes for solid state 18-crown-6 rotation-conformational reorientation motion frequently revealed by NMR methods. Luminescence and excitation spectra of 1 are normal for complexes of MnBr42-, but complex 2 features an unusual orange emission (due to crystal defects) with lambda(max) approximate to 570 nm which is sensitized by MnBr42- ions. Thermal barriers of 8 and 14 kJ mol(-1) (T < 210 K and T > 240 K, respectively) for 1 (MnBr(4)(2-)lambda(em) = 511 nm) and 2 (crystal defect lambda(em) = 610 nm) are attributed to the energy required to bridge the Stokes shifted T-4(1)((4)G) emission of the donor MnBr42- ions with the electronic origin of the T-4(1)((4)G) State on the acceptor MnBr42- during energy migration. That of 26 kJ mol(-1) (210 < T < 240 K) exhibited by 1 is attributed to the activation energy for;he 18C6 solid state motion inferable from the single, broad, featureless solid state C-13 NMR band of [(K18C6)(4)ZnBr4][TlBr4](2) (3). Crystal data for [(K18C6)(4)MBr4][TlBr4](2), where M = Mn (Zn): space group F23 and Z = 4 for both complexes; a = 20.986(7) (20.9682(7)) Angstrom, V = 9242.8(3) (9219.0(3)) Angstrom(3), number of observed data = 672 (668), R-w = 0.037 (0.039), R = 0.062 (0.036).