Selective Ion Exchange in Supramolecular Channels in the Crystalline State

Abstract

Artificial ion channels are of increasing interest because of potential applications in biomimetics, for example, for realizing selective ion permeability through the transport and/or exchange of selected ions. However, selective ion transport and/or exchange in the crystalline state is rare, and to the best of our knowledge, such a process has not been successfully combined with changes in the physical properties of a material. Herein, by soaking single crystals of Li2([18]crown‐6)3[Ni(dmit)2]2(H2O)4 (1) in an aqueous solution containing K+, we succeeded in complete ion exchange of the Li+ ions in 1 with K+ ions in the solution, while maintaining the crystalline state of the material. This ion exchange with K+ was selectively conducted even in mixed solutions containing K+ as well as Na+/Li+. Furthermore, remarkable changes in the physical properties of 1 resulted from the ion exchange. Our finding enables not only the realization of selective ion permeability but also the development of highly sensitive biosensors and futuristic ion exchange agents, for example.

Spin-ladder behaviour in molecular materials

“…The J 8 and J > parameters obtained by fitting to experimental magnetic susceptibility data gave values of respectively 86 K, 782 K for 13 and 19 K, 543 K for 14 which by eqn (5) are indicative of gaps of 701 and 524 K respectively, in fair agreement with the gap values of 657 and 537 K obtained by fit of eqn (2) to the low temperature exponential decay of susceptibility. 59 A similar spin-ladder behaviour has been also observed in other [Ni(dmit) 2 ] À salts (15-18) with amine [60][61][62][63] or lithium 64,65 cations encapsulated by crown ethers (Scheme 2), which have been studied also because of the ionic conductivity associated with supramolecular cations. 66 These salts present the previously mentioned type of ladder structure based in face-to-face p-type dimers of [Ni(dmit) 2 ] À anions, with some minor differences.…”

Review of Slow Sand Filtration for Raw Water Treatment with Potential Application in Less-Developed Countries

“…When hard water is passed through the cation exchange resin, an ion exchange process occurs between the water and the ion exchange resin, because of which the calcium and magnesium cations present in the water are adsorbed on the surface of the cation exchange resin, and sodium cations from the ion exchange resin are transferred to the water. The ion exchange process is often used to remove heavy metal cations from water and to extract various ions from industrially polluted water [19][20][21]. The efficiency of the ion-exchange process for water treatment largely depends on the exchange capacity of the sorbent, i.e., the ability of the sorbent to adsorb a certain amount of ions from the solution composition, and on the cost of regeneration of the spent sorbent.…”

Review of Slow Sand Filtration for Raw Water Treatment with Potential Application in Less-Developed Countries

“…When hard water is passed through the cation exchange resin, an ion exchange process occurs between the water and the ion exchange resin, because of which the calcium and magnesium cations present in the water are adsorbed on the surface of the cation exchange resin, and sodium cations from the ion exchange resin are transferred to the water. The ion exchange process is often used to remove heavy metal cations from water and to extract various ions from industrially polluted water [18][19][20]. The efficiency of the ion-exchange process for water treatment largely depends on the exchange capacity of the sorbent, i.e., the ability of the sorbent to adsorb a certain amount of ions from the solution composition, and on the cost of regeneration of the spent sorbent.…”