Intelligent chiral sensing based on supramolecular and interfacial concepts

Abstract

Of the known intelligently-operating systems, the majority can undoubtedly be classed as being of biological origin. One of the notable differences between biological and artificial systems is the important fact that biological materials consist mostly of chiral molecules. While most biochemical processes routinely discriminate chiral molecules, differentiation between chiral molecules in artificial systems is currently one of the challenging subjects in the field of molecular recognition. Therefore, one of the important challenges for intelligent man-made sensors is to prepare a sensing system that can discriminate chiral molecules. Because intermolecular interactions and detection at surfaces are respectively parts of supramolecular chemistry and interfacial science, chiral sensing based on supramolecular and interfacial concepts is a significant topic. In this review, we briefly summarize recent advances in these fields, including supramolecular hosts for color detection on chiral sensing, indicator-displacement assays, kinetic resolution in supramolecular reactions with analyses by mass spectrometry, use of chiral shape-defined polymers, such as dynamic helical polymers, molecular imprinting, thin films on surfaces of devices such as QCM, functional electrodes, FET, and SPR, the combined technique of magnetic resonance imaging and immunoassay, and chiral detection using scanning tunneling microscopy and cantilever technology. In addition, we will discuss novel concepts in recent research including the use of achiral reagents for chiral sensing with NMR, and mechanical control of chiral sensing. The importance of integration of chiral sensing systems with rapidly developing nanotechnology and nanomaterials is also emphasized.

Keywords: chiral sensing; interface; molecular recognition; nanomaterial; nanotechnology; supramolecular chemistry.

Figure 1.

Indicator-displacement assay.

Figure 2.

Helicity inversion based on guest binding.

Figure 3.

Modification of ITO electrode with Os complex by LB and SAM methods.

Figure 4.

Layer-type FET sensor with alkoxythiophene oligomer with chiral recognition sites.

Figure 5.

Quantification of enantiomeric excess of chiral guests by nonchiroptical spectroscopy, NMR, with achiral additives through supramolecular complex formation.

Figure 6.

Mechanical control of chiral guest binding to monolayer of cholesteryl-substituted cyclen