Jack of all trades: anion and transition metal binding by bis-triazole receptors

Abstract

Four acyclic phenylene-1,3-bis-triazole receptors were synthesised with the heterocyclic motif covalently attached to the central phenyl ring through either the carbon or nitrogen. 1 H NMR titration experiments reveal that all the receptors bind chloride in d 6 -acetone solution with the aryl-substituted systems exhibiting significantly stronger halide association than the alkyl-substituted receptors. Both N-linked systems bind chloride more strongly than their C-linked analogues. Copper(I) and silver(I) cations were also demonstrated to bind to the receptors in solution and in the solid state. Four metal complexes were structurally characterised by X-ray crystallography -in all cases giving interesting polynuclear architectures with a dinuclear silver(I) metallomacrocycle, a trimetallic copper(I) and two tetranuclear silver(I) clusters observed.

A Halogen‐Bonding Bis‐triazolium Rotaxane for Halide‐Selective Anion Recognition

“…The binding data indicate that the aryl-appended recep-tors 12 and 16 form slightly stronger complexes with almost all anions studied, compared to alkyl-appended receptors 11 and 15. This result is consistent with previously reported anion-binding behaviour of triazole-based receptors, [15] and may be due to greater preorganisation of the binding cavity in the aryl-appended receptors.…”

“…Anion [a] 11 12 15 16 Cl À 141 (15) 430 (40) 214 (6) 240(40) Br À 200(5) 337 (7) 274(5) 287 (7) (2) 295 (14) 244 (1) 213 (6) SO 4 2À [b] 341 (35) 1450 (50) 282 (10) 1030 (130) [a] Anions added as TBA salts. Association constants were calculated using WINEQNMR2, [14] with estimated standard errors given in parentheses (CD 3 CN, 298 K).…”

Increased Halide Recognition Strength by Enhanced Intercomponent Preorganisation in Triazolium Containing [2]Rotaxanes

“…Two possible causes for the increased halide anion binding affinities of 17·PF 6 and 18·PF 6 over 1·PF 6 can be postulated: the anion complexation strength of the aryl-substituted triazolium motif may be higher than the bis-alkyl-substituted due to the electron withdrawing nature of the aryl substituents increasing this protons acidity, as has been observed for acyclic triazole receptors. [58] Alternatively, the greater preorganisation provided by the shorter axle component, and the reduced opportunities for movement of the macrocycle component away from the triazolium motif could also explain the increased anion recognition strength. To investigate this further, the anion recognition properties of the three axle components, 2·BF 4 , 3·BF 4 and 4·BF 4 were investigated using 1 H NMR titration experiments in 9:1 CDCl 3 /CD 3 OD.…”

Cyclodextrin ion channels

“…70 Triazoles also bind cupric ion. 71 In simple cases these complexes are known to accelerate the cycloaddition, 72 but this is clearly ineffective in the case of the oligo-triazoles produced by cyclodextrins.…”