Qin Wang, Li-Bing Lü, Zhu Tao, Tao Sun, Qing Tang, Ying Huang
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy 2021 Jun 05In the present work, we have investigated the effect of pH and mercury ions on the host-guest complex formed between cucurbit[7]uril (Q[7]) and Hoechst 33342 (H33342). 1H NMR, UV-vis and fluorescence spectroscopy revealed that acid/base stimulation could change the binding stoichiometry between Q[7] and H33342. The results suggest that two complexation equilibria (1:1 and 2:1) may exist between H33342 and Q[7] at pH 2.0 and 4.5, respectively. However, a 1:1 host-guest complex was formed between H33342 and Q[7] at pH 7.0 and 10.0. Q[7] shows differential affinities for the protonated and neutral forms of H33342 dye. Moreover, the switching between H33342∙2H+@2Q[7](1:2) at pH 4.5 and H33342∙H+@Q[7](1:1) at pH 7.0 was reversible. Furthermore, as a metal stimulus, Hg2+ ions could push (i) Q[7] from the piperazine ring to the benzimidazole position with a 1:1 guest-host ratio and (ii) a second Q[7] onto the ethyl position with a 1:2 guest-host stoichiometry. This stimulus response system will have potential applications in the field of molecular switch design. Copyright © 2021 Elsevier B.V. All rights reserved.
Qin Wang, Li-Bing Lü, Zhu Tao, Tao Sun, Qing Tang, Ying Huang. The pH and mercury ion stimuli-responsive supramolecular assemblies of cucurbit[7]uril and Hoechst 33342. Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy. 2021 Jun 05;254:119656
PMID: 33744695
View Full Text