An Effective Fluorescent Sensor for Choline-Containing Phospholipids

Abstract

A set of weak CH small middle dot small middle dot small middle dotO interactions is responsible for the recognition of tetraalkylammonium ions (ball-and-stick structure) by the tripodal receptors depicted in the diagram, in which the binding pocket is lined with squaramide units. The association constants of the fluorescent receptors are remarkably high at about 10(5) M(-1) and can be used for signaling the presence of selected choline phospholipids. Z=RNH, where R=alkyl, arylamino; X(-)=BH(4)(-), Cl(-), Br(-), I(-).

Janus‐Like Squaramide‐Based Hosts: Dual Mode of Binding and Conformational Transitions Driven by Ion‐Pair Recognition

“…Binding studies with tetraalkylammonium iodides : A distinctive feature of squaramides compared with urea or other amide‐type groups is the hydrogen‐bond accepting abilities of the two adjacent carbonyl oxygen atoms of squaramides. We previously demonstrated the potential of the binding of the carbonyl groups of squaramides through the design of a fluorescent molecular sensor based on this exclusive ability in choline‐containing phospholipids 9c. In addition, the interaction energy between a single plain squaramide and a TMA cation (−22.00 kcal mol −1 ) is clearly favourable compared with that of urea with TMA (−16.53 kcal mol −1 ) 11.…”

The Versatility of Squaramides: From Supramolecular Chemistry to Chemical Biology

“…Some early examples of cation recognition include two pioneering papers by Ballester, Costa, and co-workers, who outline the use of squaramide-based tripodal receptors for the recognition of tetraalkylammonium compounds such as choline, acetylcholine, and related ammonium salts. 86,87 These examples of cation recognition and fluorescent sensing of membrane phospholipids were rare until more recent reports of the use of squaramides for the construction of ion-pair zwitterion receptors.…”

Introduction to Supramolecular Chemistry

“…A fluorescent sensor for barbiturates presented in Fig.6.9 makes use of the selective complexation of these guests due to hydrogen bonds formation [70]. Costa et al [71] synthesized a molecule 160 acting as a fluorescence sensor for choline-containing phospholipids. The selectivity of this sensor is also based on hydrogen bonding interactions.…”