Steric and Stereochemical Modulation in Pyridyl- and Quinolyl-Containing Ligands

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.

Electron transfer pathways in photoexcited lanthanide(iii) complexes of picolinate ligands

“…Pyridines are among the most versatile ligands for metal coordination. Transition metal pyridine and bipyridine complexes promote self-assembly 1,2 and a variety of transformations, [3][4][5][6] while their photophysical properties are used for both analyte detection 7,8 and photocatalysis. 9 The trivalent lanthanide (Ln) ions have coordination requirements that are distinct from those of the d-block metals.…”

Extending substrate sensing capabilities of zinc tris(2‐pyridylmethyl)amine‐based stereodynamic probe

“…[8][9][10][11] Tris(2-pyridylmethyl) amine (TPMA) ligands, a specific class of tripodal ligands, provide intrinsically stable complexes with well-defined coordination geometries. In the presence of suitable chromophores, this phenomenon gives rise to an intense chiroptical absorption [38][39][40] which can be monitored by electronic circular dichroism (CD). [28][29][30][31] As shown by Canary first, TPMA is characterized by a propeller-like arrangement of the ligand around the metal, [32][33][34][35][36][37] and the (non)covalent addition of a stereogenic element allows to bias the molecular system in one of the two helical configurations.…”

“…[28][29][30][31] As shown by Canary first, TPMA is characterized by a propeller-like arrangement of the ligand around the metal, [32][33][34][35][36][37] and the (non)covalent addition of a stereogenic element allows to bias the molecular system in one of the two helical configurations. In the presence of suitable chromophores, this phenomenon gives rise to an intense chiroptical absorption [38][39][40] which can be monitored by electronic circular dichroism (CD). [41][42][43][44][45] On a parallel track, in the recent years, we are assisting to a revival of interest in the well-known, and widely exploited in nature, imine condensation chemistry.…”

The Role of 8-Amidoquinoline Derivatives as Fluorescent Probes for Zinc Ion Determination

“…The aromatic ring of quinoline can be versatile and exhibit different affinities to the other metal-ligand binding. In the development of Zn 2+ chelators, N-containing ligands like quinoline have been developed and investigated [82].…”