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1. Cation specificity of vacuolar NHX-type cation/H+ antiporters

   https://doi.org/10.1104/pp.18.01103  

   Bassil, Elias ; Zhang, Shiqi ; Gong, Haijun ; Tajima, Hiromi ; Blumwald, Eduardo ( November 2018 , Plant Physiology)
2. Orthogonal, modular anion–cation and cation–anion self-assembly using pre-programmed anion binding sites

   https://doi.org/10.1039/D2SC05121D  

   Dhara, Ayan ; Fadler, Rachel E. ; Chen, Yusheng ; Köttner, Laura A. ; Van Craen, David ; Carta, Veronica ; Flood, Amar H. ( March 2023 , Chemical Science)

   Subcomponent self-assembly relies on cation coordination whereas the roles of anions often only emerge during the assembly process. When sites for anions are instead pre-programmed, they have the potential to be used as orthogonal elements to build up structure in a predictable and modular way. We explore this idea by combining cation (M + ) and anion (X − ) binding sites together and show the orthogonal and modular build up of structure in a multi-ion assembly. Cation binding is based on a ligand (L) made by subcomponent metal-imine chemistry (M + = Cu + , Au + ) while the site for anion binding (X − = BF 4 − , ClO 4 − ) derives from the inner cavity of cyanostar (CS) macrocycles. The two sites are connected by imine condensation between a pyridyl-aldehyde and an aniline-modified cyanostar. The target assembly [LM-CS-X-CS-ML], + generates two terminal metal complexation sites (LM and ML) with one central anion-bridging site (X) defined by cyanostar dimerization. We showcase modular assembly by isolating intermediates when the primary structure-directing ions are paired with weakly coordinating counter ions. Cation-directed (Cu + ) or anion-bridged (BF 4 − ) intermediates can be isolated along either cation–anion or anion–cation pathways. Different products can also be prepared in a modular way using Au + and ClO 4 − . This is also the first use of gold( i ) in subcomponent self-assembly. Pre-programmed cation and anion binding sites combine with judicious selection of spectator ions to provide modular noncovalent syntheses of multi-component architectures. 

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3. Heterogeneous Cation–Lattice Interaction and Dynamics in Triple-Cation Perovskites Revealed by Infrared Vibrational Nanoscopy

   https://doi.org/10.1021/acsenergylett.0c00522  

   Nishida, Jun ; Alfaifi, Amani H. ; Gray, Thomas P. ; Shaheen, Sean E. ; Raschke, Markus B. ( May 2020 , ACS Energy Letters)
4. Directing cation-cation interactions in thiamine compounds: Analysis of a series of organic salts based on vitamin B1

   https://doi.org/10.1016/j.molstruc.2021.130046  

   Traver, Joseph ; Chenard, Erica ; Zeller, Matthias ; Guillet, Gary L. ; Lynch, Will E. ; Hillesheim, Patrick C. ( May 2021 , Journal of Molecular Structure)

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5. A Photoprotective Effect by Cation‐π‐Interaction? Quenching of Singlet Oxygen by an Indole Cation‐π Model System

   https://doi.org/10.1111/php.13287  

   Arevalo, Gary E. ; Cagan, David A. ; Monsour, Charlotte G. ; Garcia, Arman C. ; McCurdy, Alison ; Selke, Matthias ( June 2020 , Photochemistry and Photobiology)

   We investigated the effect of the cation‐π interaction on the susceptibility of a tryptophan model system toward interaction with singlet oxygen, that is, type II photooxidation. The model system consists of two indole units linked to a lariat crown ether to measure the total rate of removal of singlet oxygen by the indole units in the presence of sodium cations (i.e. indole units subject to a cation‐π interaction) and in the absence of this interaction. We found that the cation‐π interaction significantly decreases the total rate of removal of singlet oxygen (k_T) for the model system, that is, (k_T = 2.4 ± 0.2) × 10⁸ m⁻¹ s⁻¹without sodium cationvs(k_T = 6.9 ± 0.9) × 10⁷ m⁻¹ s⁻¹upon complexation of sodium cation to the crown ether. Furthermore, we found that the indole moieties undergo type I photooxidation processes with triplet excited methylene blue; this effect is also inhibited by the cation‐π interaction. The chemical rate of reaction of the indole groups with singlet oxygen is also slower upon complexation of sodium cation in our model system, although we were unable to obtain an exact ratio due to differences of the chemical reaction rates of the two indole moieties.

    

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