resumo
Electron-deficient heavy chalcogen atoms contain Lewis acidic a sigma-holes which are able to form attractive supramolecular interactions, known as chalcogen bonding (ChB), with Lewis bases. However, their potential in solution -phase anion binding applications is only just beginning to be realized in simple acyclic systems. Herein, we explore the 5(methylchalcogeno)-1,2,3-triazole (chalcogen = Se, Te) motif as a novel ChB donor for anion binding. Other than being chemically robust enough to be incorporated into macrocyclic structures, thereby significantly expanding the scope and complexity of ChB host systems, we also demonstrate, by H-1 NMR and DFT calculations, that the chalcogen atoms oriented within the macrocycle cavity are able to chelate copper(I) endotopically. Exploiting this property, the first examples of mechanically interlocked [2]rotaxanes containing ChB donor groups are prepared via an active metal template strategy. Solution -phase H-1 NMR and molecular modeling studies provide compelling evidence for the dominant influence of ChB in anion binding by these interlocked host systems. In addition, unprecedented charge assisted ChB-mediated anion binding was also studied in aqueous solvent mixtures, which revealed considerable differences in anion recognition behavior in comparison with chalcogen-free host analogues. Moreover, DFT calculations and molecular dynamics simulations in aqueous solvent mixtures indicate that the selectivity is determined by the different hydrophilic characters of the anions allied to the hydration of the binding units in the presence of the anions. Exploiting the NMR-active nuclei of the ChB -donor chalcogen atoms, heteronuclear Se-77 and Te-125 NMR were used to directly study how anion recognition influences the local electronic environment of the chalcogen atoms in the mechanically bonded rotaxane binding sites in organic and aqueous solvent mixtures.
palavras-chave
MOLECULAR-DYNAMICS SIMULATIONS; CAMBRIDGE STRUCTURAL DATABASE; ACTIVE TEMPLATE SYNTHESIS; CROSS-COUPLING REACTION; NMR-SPECTROSCOPY; HALOGEN-BOND; COMPUTER-PROGRAM; ROTAXANES; CHEMISTRY; RECEPTOR
categoria
Chemistry
autores
Lim, JYC; Marques, I; Thompson, AL; Christensen, KE; Felix, V; Beer, PD
nossos autores
Igor Oliveira Marques
Investigador Júnior
Vítor Félix
Professor Associado com Agregaçãoagradecimentos
J.Y.C.L thanks the Agency for Science, Technology and Research, Singapore, for postgraduate funding. I.M. thanks the FCT for the Ph.D. scholarship SFRH/BD/87520/2012. The authors would like to acknowledge the Diamond Light Source for beamtime on the 119 beamline (MT13639). The theoretical studies were supported by projects P2020-PTDC/ QEQ-SUP/4283/2014, CICECO - Aveiro Institute of Materials (FCT UID/CTM/50011/2013), and iBiMED - Institute of Biomedicine (FCT UID/BIM/04501/2013), financed by National Funds through the FCT/MEC and, when applicable, cofinanced by FEDER through COMPETE, under the PT2020 Partnership Agreement.