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Synthesis, single crystal, electrochemical and study of fluorogenic dibenzodiaza-crown-appended with bis(ZnTPP) azo-tweezer and spectroscopic elucidation of photo-induced macrocycle-deformation-based chromotropism

Ghanbari, B ; Sharif University of Technology | 2022

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  1. Type of Document: Article
  2. DOI: 10.1016/j.poly.2022.116143
  3. Publisher: Elsevier Ltd , 2022
  4. Abstract:
  5. In the present research, a new tweezer T bearing azobenzene linker 1 was prepared, characterized by applying FT-IR spectroscopy, fluorescence spectroscopy, UV–visible spectroscopy, and elemental analysis 1H and 13C{1H} NMR. T crystals were obtained by reaction of 1 with ZnTPP in CHCl3/acetone. Under irradiation with a mercury lamp to achieve the trans-to-cis isomerization, a dramatic color change from violet to green in chloroform was observed. The X-ray crystallography of T revealed an observable macroring deformation of the ZnTPP for the trans isomer. We observed a deviation of 0.11 Å from planarity for the least-squares plane of ZnTPP owing to the axial coordination by the pyridine derivative of the parent dibenzodiaza-crown moieties of 1. Hence, we suggested the existence of oop deformations for this photo-responsive chromogenic colour change. Fluorescence (FL) spectrophotometry was applied to elucidate the observed colour change in terms of the ring deformation of ZnTPP, resulting from the trans-to-cis photo-isomerization of the azo-linker moiety of L. This is the first report on the gradual reversible photochromism of ZnTPP moiety, based on the macrocycle-deformation mechanism, wherein colour color change of T was reversible at 60 °C. The CVs of ZnTPP in various concentrations of 1 were examined. The titration of ZnTPP by 1 displays the positive shift of the oxidation potential of ZnTPP in the CV, indicating the complex formation between ZnTPP and 1 in CH2Cl2. © 2022 Elsevier Ltd
  6. Keywords:
  7. Chromotropism ; Cis-trance isomerization ; Macrocyclic ligand ; Tweezer
  8. Source: Polyhedron ; Volume 227 , 2022 ; 02775387 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/abs/pii/S0277538722004958