,'-(subst1tuted)-4,13-diaza-18-crown-6 derivatives having pi-donor-group-sidearms: correlation of thermodynamics and solid state structures

Experimental Evidence for Alkali Metal Cation−π Interactions

“…The sidearms are n-propyl (4), [80] allyl (5), [23] propargyl (6), [23] and cyanomethyl (7). [81] Figure 5. The crystal structures of three BiBLEs; (a) the unbound structure of 8; [81] (b) the anti KI complex of N,NЈ-bis(2-hydroxyethyl)-1,10-diaza-18-crown-6; [83c] (c) the syn KI complex of N,NЈ-bis(2-methoxyethyl)-1,10-diaza-18-crown-6 [83c] All four compounds have three-atom, linear chains and 4؊6 increase in relative unsaturation at the distal terminus of the sidearm.…”

“…[81] Figure 5. The crystal structures of three BiBLEs; (a) the unbound structure of 8; [81] (b) the anti KI complex of N,NЈ-bis(2-hydroxyethyl)-1,10-diaza-18-crown-6; [83c] (c) the syn KI complex of N,NЈ-bis(2-methoxyethyl)-1,10-diaza-18-crown-6 [83c] All four compounds have three-atom, linear chains and 4؊6 increase in relative unsaturation at the distal terminus of the sidearm. The sidearms of 6 and 7 are isosters although the latter differs in the terminal atom and dipole.…”

Probing the influence of solvent effect on the lithium ion binding affinity of 12-crown-O3N derivatives with unsaturated side arms: A computational study

“…However, generally the unsaturated side-arms enhance the binding affinity of Li + ion with 2 and 3 compared to 1 in respective A c c e p t e d M a n u s c r i p t 15 solvent medium. The role of solution thermodynamics has been observed beside the auxiliary effect of such side-arms in the receptor molecules [12].…”

“…N-pivot lariat ethers are known to have better cation-binding than C-pivot lariat ethers as the nitrogen atom provides a flexible sidearm due to its ability to perform an inversion in space [11]. It is also reported that if sidearms do not interact directly with the ring-bound cation, they may influence the binding by competing with solvent or counter ion [12]. Investigations related to stable structures of 12-crown-O 3 N complexes with Li + / Na + cation in aqueous and acetonitrile solutions were done by Kenzi Hori et al [13][14][15].…”

Tryptophan in Membrane-Active Synthetic Antimicrobials

“…47 Unfortunately, attempts to do so in the 1980s failed, owing to a poorly designed model system. 48 A slight modification of the lariat ether, from Ar-CH 2 <N18N>CH 2 -Ar to Ar-CH 2 CH 2 <N18N>CH 2 CH 2 -Ar, bore the hoped-for fruit. 49 Ultimately, cation-pi complexation of Na + and K + was demonstrated for phenyl, phenol and indole.…”