Helix-Like Receptors for Perrhenate Recognition Forming Hydrogen Bonds with All Four Oxygen Atoms

Abstract

Supramolecular recognition of perrhenate is a challenging task due to therelatively large size and low charge density of this anion. In this work, we design and synthesize a family of helix-like synthetic receptors that can bind perrhenate by forming hydrogen bonds with all four oxygen atoms of the anion. Among the investigated rigid helix-forming subunit derived from 1,1′-ferrocenedicarboxylic acid, 1,3-phenylenediacetic acid and 2,2′-(ethyne-1,2-diyl)dibenzoic acid, the latter one shows the best selectivity for perrhenate recognition. However, the receptor based on 1,1′-ferrocenedicarboxylic acid demonstrates selectivity to bind chloride in a 1:2 fashion. The properties of the receptors are investigated in the acetonitrile solution by using NMR, UV–Vis, and in the solid state by single crystal X-ray analysis.

Spectroscopic and Colorimetric Studies for Anions with a New Urea-Based Molecular Cleft

“…In recent years, a substantial amount of work on urea-based and thiourea-based neutral anion receptors has been reported in the literature [23][24][25][26][27][28]. Molecules with certain functional groups, such as urea, thiourea, amides and other NH-bearing derivatives, are often introduced in the structural designing of chemosensors [29][30][31][32][33][34][35][36][37] to facilitate efficient binding with anions due to their directional hydrogen-bonding ability with anions [38][39][40]. The increased polarity of an NH unit owing to the presence of electron-withdrawing groups in the structure further enhances an anion binding event offering strong H-bonding interactions [41].…”