三元混配合物分子内的芳环堆积作用Ⅲ——核磁共振法研究Pd^(2+)—A(phen、bpy、trp)—UTP^(4-)体系

The Intramolecular Aromatic-Ring Stacking Interaction of Mixed Ligand Palladium(Ⅱ) Complexes Ⅲ——Studies on the Pd-A-UTP^(4-) System by ~1HNMR Method

用~1HNMR法测定Pd^(2+)-A-UTP^(4-)体系中混配合物Pd(A)(UTP)^(2-)分子内的芳环堆积作用,A=邻氮二菲,Phen;2,2′-联吡啶(bpy)和色氨酸(trp^-);UTP^(4-)=尿苷-5′-三磷酸盐,认为由于UTP^(4-)中嘧啶环与A中的芳香杂环间发生部份堆积,使得UTP^(4-)分子内H(5)、H(6)和H(1′)发生明显的高场位移.混配合物中的芳环堆积作用按下列顺序减小:Pd(Phen)(UTP)^(2-)>Pd(bpy)(UTP)^(2-)>Pd(trp)(UTP)^(3-).这一变化恰与A的芳环大小相一致,即Phen>bpy>trp^-.

The aromatic ring stacking interaction of the Pd-A (A=phen, bpy and trp)-UTP4- systems have been studied by 1H NMR method. The resonances of H(5), H(6) and H(1') of UTP for the Pd(A)(UTP)2- are shifted upfield, therefore, it indicates that the stacking isomer of the Pd(A) (UTP)2- are presented in solution. The degree of formation of stacked isomer decreses Pd(phen)(UTP)2->Pd(bpy)(UTP)2->Pd(trp)(UTP)3-. Also, the stacked interaction of ternary complexes depends on the size of aromatic ring phen>bpy>trp.