Structural reinforcement of a large macrocyclic ligand. A structural, molecular mechanics, and thermodynamic study
作者:Peter W. Wade、Robert D. Hancock、Jan C. A. Boeyens、Susan M. Dobson
DOI:10.1039/dt9900000483
日期:——
with the ligands. The successive insertion of ethylene bridges into the 1,4-diaminoethane units in L5 enhances the selectivity of the ligand for large metal ions, with L7 binding only to Pb2+. The selectivity of these ligands and the depression of the formation constants with all metal ions upon successive insertion of the ethylene bridges are rationalised with the aid of molecular mechanics calculations
大环L 5(1,10 -dioxa-4,7,13,16-四氮杂双环十八烷),L 6(4,13-dioxa-1,7,10,16-四氮杂双环[[ 14.2.2]二十烷)和L 7(4,13-dioxa-1,7,10,16-四氮杂-三环[14.2.2.2 7,10 ]二十二烷)已合成,并且它们的络合物形成常数由Cu确定2+,Ni 2 +,Zn 2 +,Cd 2+和Pb 2+;发现离子Sr 2+和Ba 2+不与配体络合。乙烯桥连续插入L 5中的1,4-二氨基乙烷单元中L 7仅与Pb 2+结合,从而增强了配体对大型金属离子的选择性。这些配体的选择性以及在乙烯桥连续插入后所有金属离子的形成常数的降低都借助分子力学计算得以合理化。已确定L 7的游离配体的晶体结构:空间群P 2 1 / n,单斜晶,a = 6.053(2),b = 14.190(8),c = 10.346(6)Å,β= 106.82 (4)°,Z