Interplay of Hydrophobic and Electrostatic Interactions in Modulation of Protonation–Deprotonation Equilibria of Two Positional Isomers in Their Complexes with Cucurbiturils
| Autor: | Anindya Datta, Vijaykant Khorwal, Sohidul Islam Mondal, Uma Nudurupati |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Benzimidazole
Molecular Containers Supramolecular Assemblies Protonation High-Energy Water 010402 general chemistry 01 natural sciences chemistry.chemical_compound Deprotonation Cucurbituril Computational chemistry Structural isomer Molecule Physical and Theoretical Chemistry Nafion Membranes Aqueous-Solution Inclusion Complexes Host-Guest Complexation 010405 organic chemistry Chemistry Tautomer 0104 chemical sciences Surfaces Coatings and Films Electronic Optical and Magnetic Materials General Energy Reverse Micelles Excited state Dual Fluorescence Selective Enhancement |
| Zdroj: | The Journal of Physical Chemistry C. 121:5379-5388 |
| ISSN: | 1932-7455 1932-7447 |
| DOI: | 10.1021/acs.jpcc.6b13006 |
| Popis: | Elucidation of host-guest chemistry of 2-(4'pyridyl)benzimidazole (4PBI) and 2-(2'-pyridyl)benzimidazole (2PBI) with cucurbiturils in aqueous solution is rather challenging. The guest molecules are capable of binding in three different states of protonation: cation C, tautomer T, and normal N. Charge distribution on the species governs the formation of the inclusion complexes. Binding modes of the guest molecules with cucurbiturils have been investigated by proton NMR spectroscopy. 4PBI binds with its benzimidazole ring pointing inward,, while the binding mode is opposite for 2PBI. This difference is governed by the position of substitution of the pyridyl ring. Energetics of complexation has been studied by quantum chemical calculations for 4PBI-CB as 2PBI-CB type complexes, for each form (C, T, and N) of both the molecules. Release of high energy water from cucurbituril cavity is the main driving force for complexation. Excited state proton transfer (ESPT) in 2PBI and 4PBI are affected strongly upon complexation, as is manifested in steady state and time-resolved fluorescence experiments. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|