Adamantylated trisimidazolium-based tritopic guests and their binding properties towards cucurbit[7]uril and beta-cyclodextrin

Two new homotritopic guests based on tris(benz) imidazolium salts with adamantane binding sites were prepared. NMR and calorimetric titration experiments revealed that each of the three sites independently binds beta-cyclodextrin (beta-CD) or cucurbit[7]uril (CB7) units to form binary host-guest complexes with 1:3 stoichiometry. The association constants for the single binding site for beta-CD and CB7 were determined using titration calorimetry and are in the order of 10(5) and 10(9-10) dm(3) mol(-1), respectively. In addition, both guests were able to form ternary systems with beta-CD and CB7 in ratios of 1:1:2 and 1:2:1, respectively.Internal Funding Agency of the Tomas Bata University in Zlin [IGA/FT/2015/005

A photochemical/thermal switch based on 4,4′-bis(benzimidazolio)stilbene: Synthesis and supramolecular properties

Stilbene derivatives are well-recognised substructures of molecular switches based on photochemically and/or thermally induced (E)/(Z) isomerisation. We combined a stilbene motif with two benzimidazolium arms to prepare new sorts of supramolecular building blocks and examined their binding properties towards cucurbit[n]urils (n=7, 8) and cyclodextrins (β-CD, γ-CD) in water. Based on the 1H NMR data and molecular dynamics simulations, we found that two distinct complexes with different stoichiometry, i. e., guest@β-CD and guest@β-CD2, coexist in equilibrium in a water solution of the (Z)-stilbene-based guests. We also demonstrated that the bis(benzimidazolio)stilbene guests can be transformed from the (E) into the (Z) form via UV irradiation and back via thermal treatment in DMSO. © 2020 Wiley-VCH GmbHInternal Funding Agency of Tomas Bata University in Zlin [IGA/FT/2020/001]; Ministry of Education, Youth and Sports of the Czech Republic (MEYS CR) under the National Sustainability Programme II project CEITEC 2020 [LQ1601]; programme `Large Infrastructures for Research, Experimental Development and Innovations' by MEYS CR [LM2015042, LM2015085, LM2015070]; MEYS CR [LM2018127