已经报道了以均三甲苯/三乙苯作为核心部分、尿素/硫脲作为结合基团和对硝基苯作为信号单元的七种中性三足和双足受体。受体充当用于小型和球形F离子的选择性比色,肉眼传感器,其来自四面体离子的干扰。硫脲衍生物与 F− 阴离子形成稳定的 1:1 H 键配合物,并在一定程度上与阴离子形成稳定的 1:1 H 键配合物,而对于尿素衍生物,识别仅基于脲酸质子和碱性 F− 离子之间的酸碱反应,并且是完全可逆的现象。硫脲衍生物的预组织及其高内在酸度应该有助于它们与 F-阴离子形成强 H 键复合物。尿素基受体在较低浓度的阴离子时不响应,
Synthesis of new tripodal receptors—a ‘PET’ based ‘off–on’ recognition of Ag+
摘要:
A new set of tripodal receptors based upon an aromatic platform have been synthesized in high yields. The compounds have been characterized by spectroscopic techniques and by single crystal X-ray crystallography. These receptors are found to have good extraction ability and high transport rate for Ag(I). The receptor with imine linkages exhibits weak fluorescence emission bands lambda(max)=413 and 540 nm, upon excitation lambda(max)=365 nm. The fluorescence spectrum of the receptor shows enhancement in the intensity of the signal at 413 nm on binding with the Ag+ cation. No such significant changes are observed with other metal ions. An absorption at similar to 365 nm is typical of an intraligand (pi-pi*) transition involving the imine chromophore, which produces a weak emission band at 413 nm due to quenching caused by PET from a neighboring -OH group. Participation of OH group in coordination to the metal ion reduces PET and an enhancement of fluorescence intensity is observed, signaling recognition of the metal ion. (C) 2008 Elsevier Ltd. All rights reserved.