Design and Synthesis of Calcium and Magnesium Ionophores Based on Double-Armed Diazacrown Ether Compounds and Their Application to an Ion Sensing Component for an Ion-Selective Electrode

Abstract

The double-armed diazacrown ethers, which have a base diazacrown ether ring with two diamide-type side chains, were designed and synthesized on the basis of the proposed molecular model for the novel neutral Ca2+ and Mg2+ ionophores. The potentiometric ion-selective electrodes were prepared with over 20 kinds of systematically synthesized diazacrown ether derivatives. The relationship between the molecular structures of the ionophores and the ion selectivities was fully discussed. The electrodes based on the 21and 18-membered diazacrown ether derivatives possessing a glycolic diamide and malonic diamide in their side chains (K23E1 and K22B5) exhibited excellent Ca2+ and Mg2+ selectivities, respectively. The ion-selectivity features of the novel Ca2+ and Mg2+ ionophores supply important structural information about the design of host molecules for alkaline earth metal cations.Calcium is one of the essential electrolytes in the human body, and its biological actions nave been actively investigated.1'* 12 345678*For monitoring this important electrolyte, a calcium ion-selective electrode, which is a convenient chemical sensor, has been successfully developed and utilized.3-5 Magnesium is also an important blood electrolyte. Nevertheless, despite the large demand for monitoring Mg2+ in human and animal bodies, a Mg2+selective electrode with adequate characteristics satisfying the requirement for blood analysis has not been developed to date. In the past, several Mg2+-selective ionophores for an ion-selective electrode, which were mostly /3-diketone types, were investigated.4-9

Host–Guest Interactions in ExBox4+

“…1,2 The invention of Crown ether by Perdersen 3 started a new age in supramolecular chemistry including "host-guest interaction". , is also synthesized that can bind π-electron rich as well as π-electron deficient hydrocarbons.…”

Rapid Determination of Calcium in Milk and Water Samples by Reflectance Spectroscopy

“…Immobilized arsenazo III [12,13], chlorophosphonazo III [14], and amine-containing calcium green derivative [15] in various matrices were used for molecular spectroscopic calcium sensing based on reflectance [12], absorbance [13,14] and fluorescence [15] mesurements. A number of Ca(II) membrane sensors based on different ion carriers have also been reported [16][17][18][19][20][21][22][23]. It should also be added that many data on analyte/polymer interactions are based on empirical information, and physico-chemical explanations on interaction mechanisms still remain relatively speculative [23].…”

Electrode Chemistry Yields a Nanoparticle-Based NMR Sensor for Calcium

“…To examine whether an ion-selective electrode chemistry could be adapted to obtain an NP-based assay for ions, we examined the interaction of calcium ions with NPs featuring the diglycolic amide motif because calcium-sensitive electrodes have employed this approach. [8][9][10] …”