Preorganized Metallomacrocycles: Improved Binding and Selectivity of NH<sub>3</sub> over Primary Amines
作者:Frank C. J. M. van Veggel、Hettie G. Noorlander-Bunt、William L. Jorgensen、David N. Reinhoudt
DOI:10.1021/jo971943q
日期:1998.5.1
Three new metallohosts (2-4) mere synthesized by the uranyl-templated macrocyclization of the appropriate dialdehydes 13a-c and 1,2-phenylenediamine in methanol. Cyclization of the dialdehyde 13b led to two isomers (3a, major, and 3b, minor), which only differed in the orientation of the isopropyl substituents on the outer phenolic rings of the terphenyl moiety. The binding constants in CDCl3 of ammonia and benzylamine were determined by H-1 NMR spectroscopy. The binding of ammonia by these hosts follow 1 approximate to 2 approximate to 4 < 3b < 3a. The binding of benzylamine follows 1 approximate to 2 approximate to 4 approximate to 3b << 3a. Monte Carlo, free-energy perturbation calculations reproduced the binding of ammonia and n-propylamine quite well. The much larger binding of benzylamine by host 3a was rationalized by a much deeper positioning of the guest in the cavity of the host compared to 3b.