Discovery of anion–π interactions in the recognition mechanism of inorganic anions by 1,2,3-triazolium rings

Abstract

The simultaneous action of two noncovalent interactions in solution, hydrogen-bonding and anion–π, resulted in a selective receptor for HP2O73− anions.

Why is Ferrocene so Exceptional?

“…Indeed, interaction of the intradendritic triazole groups with the transition-metal cations Cu I , Cu II , Pd II , and Au III led to their redox recognition by cyclic voltammetry. [301,302] Various other ferrocene-containing dendrimers have been reported, their electrochemical properties providing useful information on interfacial electron-transfer properties and redox-recognition features. [303][304][305][306][307][308] Giant ferrocene-terminated dendrimers containing up to 15000 ferrocene or pentamethylferrocene termini were synthesized, and both the ferrocene and ferricinium forms were characterized by electronic microscopy with the termini showing the redox "breath-ing" like molecular machines between the reduced and oxidized forms, the latter experiencing coulombic repulsion between charges that expanded the polycationic metallodendrimer size [Equation (8)].…”

“…The first syntheses of clicked 1,2,3‐triazolylferrocene‐terminated dendrimers in 2007 and of clicked 1,2,3‐triazolylbiferrocene‐terminated dendrimers of several generations in 2010 offered the potential for redox sensing of oxoanions and transition‐metal cations at the same time, again with positive dendritic effects (i.e., increased ion–dendrimer interactions as the dendrimer generation increased). Indeed, interaction of the intradendritic triazole groups with the transition‐metal cations Cu I , Cu II , Pd II , and Au III led to their redox recognition by cyclic voltammetry , . Various other ferrocene‐containing dendrimers have been reported, their electrochemical properties providing useful information on interfacial electron‐transfer properties and redox‐recognition features .…”

Strong Affinity of Triazolium-Appended Dipyrromethenes (TADs) for BF4−

“…The mono-alkylated triazolium was prepared by the addition of methyl iodide, while the bis-triazolium was synthesized using the Meerwein’s salt ( Scheme 2 ) [ 18 ]. At last, the tetrafluoroborate anion was chosen as the final counter anion, because it is known to generally display low affinity for anion receptors [ 1 , 2 , 3 , 4 ].…”

“…Accordingly, the development of robust and selective systems is of prime interest. While studying anion recognition by positively charged hosts, researchers usually use fluorinated anions such as BF 4 − and PF 6 − as the counter anions [ 1 , 2 , 3 , 4 ], because these weakly coordinating anions do not compete with the coordination of more basic anions such as halides, carboxylates, nitrates, and so on. However, some rare examples are found in the literature in which these supposedly “innocent” fluorinated anions are involved in the assembly of cage complexes, [ 5 , 6 , 7 , 8 , 9 ] suggesting that they should not be considered as totally innocent.…”

Fluorescent triazolium for sensing fluoride anions in semi-aqueous solution

“…[41][42][43] Several groups, including ours, have used triazolium as a platform for anions recognition. [44][45][46][47][48][49][50][51] Thus, a series of triazolium-based probe for uorescence sensing of F À , H 2 PO 4…”