Spontaneous resolution of a novel chiral coordination polymer through supramolecular interactions and solvent symmetry breaking

The spontaneous resolution reaction of racemic trans-2,3-dihydro-2,3-dipyiidyl-benzo[e]indole 1 with Cd(ClO4)(2)center dot 6H(2)O in the presence of 2-butanol under solvothermal reaction conditions favors the formation of crystal 2 [P-Cd(R,R,-1)2(ClO4)(2)], while a similar reaction in the presence of ethanol only favors the formation of crystal 3 [M-Cd(S,S,-1)2(ClO4)(2)]. The crystal structural determination shows that both 2 and 3 crystallize in chiral enantiomorphous space groups (P6(1)22 and P6(5)22) and their structures are ID infinite chain, and are just enantiomorphous pairs most like. The spontaneous resolution process displays estimated ee values of ca. +0.6 for 2-butanol and ca. -0.4 for ethanol. Enantiomerically pure (S,S)-trans-2,3-diliydro-2,3-dipyridyl-benzo[e]-indole (S,S,-1) can be obtained through the decomposition of mechanically separated 3. Additionally (S,S,-1) also crystallizes in a chiral space group (P2(1)). The CD (circular dichroism) spectra of both 2 and 3 in the solid state are also approximately enantiomorphous pairs. However, their fluorescent spectra in the solid state display a moderate difference in maximum emission peaks (Delta lambda = 19 nm). Crystal data for 2: C44H34Cl2N6O8Cd, M = 958.07, hexagonal, P6(1)22, a = 10.5488(5), c = 68.256(4) angstrom, alpha =gamma = 90 degrees, beta = 120 degrees, V = 6577.8(6) angstrom(3), Z = 6, D-c 1.451 mg m(-3), R-1 = 0.0498, wR(2) = 0.1124, mu = 0.679 mm(-1), S = 0.623, Flack chi = -0.02(6). For space group P6(5)22, R-1 = 0.0670, wR(2) = 0. 1602, S = 0.725 with a Flack value of 1.03(7); Crystal data for 3, C44H34Cl2N6O8Cd, M = 958.07, hexagonal, P6(5)22, a = 10.5446(3), c = 68.265(3) angstrom, V = 6573.3(4) angstrom(3), Z = 6, D-c = 1.452 mg m(-3), R-1 = 0.0444, wR(2) = 0.1002, mu = 0.679 mm(-1), S = 0.558, Flack chi = 0.01(5). For space group P6(1)22, R-1 = 0.0501, wR(2) = 0. 1178, S = 0.599 with a Flack value of 1.00(5). The low Flack parameter indicates that the absolute configurations of 2 and 3 are stated; Crystal data for (S,S)-2, C22H17N2, M = 323.39, orthorhombic, P2(1)2(1)2(1), a = 9.2598(7), b = 9.4617(8), c = 19.1452(16) angstrom, V = 1677.4(2) angstrom(3), Z = 4, D-c = 1.281 mg m(-3), R-1 = 0.0417, wR(2) = 0. 1191, T = 293 K, mu = 0.077 mm(-1), S = 0.862. (C) 2005 Published by Elsevier Ltd.