Whither Second-Sphere Coordination?

Abstract

The properties of coordination complexes are dictated by both the metals and the ligands. The use of molecular receptors as second-sphere ligands enables significant modulation of the chemical and physical properties of coordination complexes. In this Mini-Review, we highlight recent advances in functional systems based on molecular receptors as second-sphere coordination ligands, as applied in molecular recognition, synthesis of mechanically interlocked molecules, separation of metals, catalysis, and biomolecular chemistry. These functional systems demonstrate that second-sphere coordination is an emerging and very promising strategy for addressing societal challenges in health, energy, and the environment.

Tuning primary and secondary coordination spheres of ruthenium complexes for the homogeneous water oxidation reaction: a perspective from catalytic activity and overpotential

“…36,38,39 For instance, literature studies have demonstrated that smallmolecule catalysis, such as the reduction of CO 2 , O 2 , H + , and oxidation of NH 3 and H 2 O, could benefit rationally by finetuning the secondary coordination sphere of the corresponding catalysts. [40][41][42][43][44][45][46] The manipulation of the secondary coordination sphere of Ru-based WOCs has primarily been achieved via non-covalent interactions, such as hydrogen bonding, π-π stacking, hydrophobic/hydrophilic effects, steric hindrance, and electronic influence. 38,39 Although various approaches have been employed to control the primary and secondary coordination spheres of Ru catalysts toward the WOR, 47 there is minimal information on the cross-comparison of these studies from the kinetic and thermodynamic points of view.…”

Detection of the UV-vis silent biomarker trimethylamine-N-oxide via outer-sphere interactions in a lanthanide metal-organic framework

“…The sensing functions of high sensitivity, high selectivity and low systematic error can be achieved by lanthanide MOFs with two emission centers because of their excellent self-calibration function and color gradient feature originated from the multi-emission centers 26 – 31 . To achieve high-performance recognition for UV-vissilent TMAO, a well-matched host-guest interaction between the inner and outer coordination sphere in lanthanide MOFs is essential 32 . Since TMAO is an electron donor, the functionalization of lanthanide MOFs by an electron acceptor is a rational approach, but it has not been realized in MOF chemistry.…”

Mechanical Bond-Assisted Full-Spectrum Investigation of Radical Interactions

“…Noncovalent bonding interactions − lay the foundation for almost all the communications between molecules in chemical and biological systems, such as molecular recognition, − self-assembly, − signal transduction, , and catalysis. − Understanding these interactions not only can offer keys to mimicking , the structural and functional aspects of living systems, but also can enrich the toolkit for advanced noncovalent syntheses. − Whereas the dynamic nature of noncovalent bonding interactions is beneficial − for the construction of smart materials with responsiveness and adaptivity, a large proportion of these interactions are weak, labile, and sometimes transient, making it difficult to characterize and investigate them in depth. Particularly when it comes to complicated supramolecular systems involving multiple interactions, the contribution of weak interactions tends to be obscured by stronger ones.…”