Abstract: By method of UV-Vis spectraophotometric titration molecular recognition behavior of novel chiral asymmetry Salen Ni complexes(Host 1 and Host 2) with imidazoles and diamines in CHCl₃ were studied. The results showed that the association constants decreased in the orders of K^θ(ethane-1,2-diamine)＞K^θ(propane-1,2-diamine)(diamine derivatives) and K^θ(Im)＞K^θ(N-MeIm)＞K^θ(2-MeIm)＞K^θ(2-Et-4-MeIm)(imidazole derivatives). When Salen Ni(host 1) reacts with 2-Et-4-MeIm, the coordination number is 1. In other systems the coordination number is 2. The thermodynamic functions Δ_rH^θ_m, Δ_rS^θ_m were also measured. The results indicated the processes were exothermic and entropy decreasing. The CD spectra of host-guest system was studied and the results were consistent with those of thermodynamics. Moreover, the lowest energy configurations of host-guest system were obtained by simulated annealing, and quantum chemical calculation was performed based on the configuration to explain the experimental results.

Key words: Chiral asymmetry Salen Ni complex, Molecular recognition, CD spectrum, Quantum chemical calculation