Synthesis and Binding Properties of Hybrid Cyclophane-Azamacrocyclic Receptors

摘要

Three new azamacrocyclic-cyclophane hybrid receptors L_1,L_2,and L_3 have been synthesized that incorporate either 1,4,7,10-tetraazacyclododecane(cyclen)or 1,4,7-triazacyclononane(tacn)unit-(s)tethered via a short amidic spacer to an electron donor and a H-bonding crown ether polycycle.The crown ether is designed to act as a host toward biologically relevant guests,whereas the macrocycle can coordinate a zinc(II)or a copper(II)ion.The pK_a of this bound water in the zinc(II)complex of L_1 and L_2 is approx7.5.Isothermal calorimetry experiments carried out on [ZnL_1(OH_2)](CF_3-SO_3)_2 and [Zn_2L_2(OH_2)_2](CF_3SO_3)_4 in buffered water(pH 7.4)at 25 deg C show that the host strongly binds a series of phosphate derivatives.In comparison,the complex [CuL_3(OH_2)_2](CF_3SO_3)_2 is a poor receptor toward phosphate substrates.