Proton−Lithium Binding Behavior of Tris(2-((pyrid-2-ylmethyl)uredio)ethyl)amine

Abstract

Tris(2-((pyrid-2-ylmethyl)uredio)ethyl)amine (2) and its perchlorate salt, 2.HClO(4), bind with Li+ in nitromethane in a 1:1 fashion. The stability constants of K(Li+) and K(H)(Li+) were found to be 112 +/- 25 and 130 +/- 30 M(-)(1) in CD(3)NO(2), respectively. Formation of the 1:1 complexes were further evidenced by electrospray ionization mass spectrometry (ESI-MS). The slight increase, or at least the same order of magnitude, of K(H)(Li+) compared to K(Li+) points to a remarkable preorganization of the protonated podand in 2.HClO(4), that essentially overcomes the increased Columbic repulsion occurring on complexation to Li+.

Synthesis and Complexing Properties of [2.n](2,6)Pyridinocrownophanes

“…Electrospray ionization mass spectroscopy (ESI-MS) is one of the most simple and useful methods to disclose the complexing behavior of host compounds with cations in a polar homogeneous system. , Gokel and Wang clarified that the K + /Na + binding selectivity of 18-crown-6 studied by ESI-MS in methanol is in good agreement with that obtained by ion-selective electrode techniques in the same solvent . We have been examined alkali metal cation selectivity of four-bridged crownophanes and bisbenzocrown ethers bridged by cyclobutane ring by ESI-MS.…”