Abstract
Nitrogen-containing pyridine and quinoline are outstanding platforms on which excellent ionophores and sensors for metal ions can be built. Steric and stereochemical effects can be used to modulate the affinity and selectivity of such ligands toward different metal ions on the coordination chemistry front. On the signal transduction front, such effects can also be used to modulate optical responses of these ligands in metal sensing systems. In this review, steric modulation of achiral ligands and stereochemical modulation in chiral ligands, especially ionophores and sensors for zinc, copper, silver, and mercury, are examined using published structural and spectral data. Although it might be more challenging to construct chiral ligands than achiral ones, isotropic and anisotropic absorption signals from a single chiroptical fluorescent sensor provide not only detection but also differentiation of multiple analytes with high selectivity.
Highlights
As nitrogen-containing aromatic compounds, pyridine and quinoline can form complexes with many metal ions because the lone pair electrons on the nitrogen are available for coordination since they are not part of the aromatic systems
Be explained by by the nature of the targeted anions. It is more specific than regular fluorescence fluorescence, circular dichroism dichroism (CD), and Ln(III)-luminescence signals of the anion-bound complex, which are controlled the presence of a fluorescent quinoline and a stereocontrolled methyl group resulting in differences by the nature of the targeted anions [64]
Metal ion sensing by such chiroptical fluorescent sensors through both fluorescence and anisotropic absorption distinguishes (Figure 23), for example, Hg2+ (enhanced fluorescence with strong positive exciton coupled CD (ECCD)), Zn2+, Cu2+, Ni2+, Pb2+, Cd2+
Summary
As nitrogen-containing aromatic compounds, pyridine and quinoline can form complexes with many metal ions because the lone pair electrons on the nitrogen are available for coordination since they are not part of the aromatic systems. Chiral pyridyl- or quinolyl-containing ligands and their metal complexes are used as catalysts in asymmetric catalysis [1]. A recent review described the design principle for selective metal ion binding and sensing using many achiral pyridyl-containing ligands [2]. There are some other examples of achiral pyridyl-containing ligands used for metal sensing and this article will discuss the structural features of some of them [3,4,5,6]. This article mainly focuses on the stereochemical approach to achieving selective metal binding and sensing using pyridyl-/quinolyl containing ligands, especially chiral ligands. The structure-activity relationship in the modulation of coordination chemistry and/or signal transduction using such ligands/sensors will be discussed
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
