Direct Access by Mechanochemistry or Sonochemistry to Protonated Merocyanines

Components of a Four‐State Molecular Switch

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Abstract

Direct access to the protonated merocyanine forms of two substituted spiropyrans by mechanosynthesis or sonochemistry was explored. The compounds were formed by the condensation reaction of the methyleneindolium iodide salt with salicylaldehyde derivatives. X‐ray crystallography, 1H NMR spectroscopy, ab initio geometry optimization, and absorption spectroscopy were combined to provide a better understanding of the four‐state molecular switch system in which the newly synthesized protonated merocyanines were found to play a central role. The results of this study suggest that the stability of the protonated merocyanines requires acidic conditions, as treatment with base led to the corresponding unprotonated merocyanines, which in turn spontaneously converted into photochromic closed spiropyrans.
Original languageEnglish
Pages (from-to)520-526
Number of pages7
JournalChemistryOPEN
Volume7
Issue number7
DOIs
Publication statusPublished - 2 Jul 2018

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Sonochemistry
Switches
Condensation reactions
Crystallography
Iodides
Absorption spectroscopy
Salts
Spectroscopy
Derivatives
Geometry
merocyanine

Keywords

  • merocyanines
  • molecular devices
  • spiro compounds
  • UV/Vis spectroscopy
  • X-ray diffraction

Cite this

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title = "Direct Access by Mechanochemistry or Sonochemistry to Protonated Merocyanines: Components of a Four‐State Molecular Switch",
abstract = "Direct access to the protonated merocyanine forms of two substituted spiropyrans by mechanosynthesis or sonochemistry was explored. The compounds were formed by the condensation reaction of the methyleneindolium iodide salt with salicylaldehyde derivatives. X‐ray crystallography, 1H NMR spectroscopy, ab initio geometry optimization, and absorption spectroscopy were combined to provide a better understanding of the four‐state molecular switch system in which the newly synthesized protonated merocyanines were found to play a central role. The results of this study suggest that the stability of the protonated merocyanines requires acidic conditions, as treatment with base led to the corresponding unprotonated merocyanines, which in turn spontaneously converted into photochromic closed spiropyrans.",
keywords = "merocyanines, molecular devices, spiro compounds, UV/Vis spectroscopy, X-ray diffraction",
author = "Melwin Cola{\cc}o and Andr{\'e}a Carletta and {Van Gysel}, M{\'e}gane and Koen Robeyns and Nikolay Tumanov and Johan Wouters",
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T1 - Direct Access by Mechanochemistry or Sonochemistry to Protonated Merocyanines

T2 - Components of a Four‐State Molecular Switch

AU - Colaço, Melwin

AU - Carletta, Andréa

AU - Van Gysel, Mégane

AU - Robeyns, Koen

AU - Tumanov, Nikolay

AU - Wouters, Johan

PY - 2018/7/2

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AB - Direct access to the protonated merocyanine forms of two substituted spiropyrans by mechanosynthesis or sonochemistry was explored. The compounds were formed by the condensation reaction of the methyleneindolium iodide salt with salicylaldehyde derivatives. X‐ray crystallography, 1H NMR spectroscopy, ab initio geometry optimization, and absorption spectroscopy were combined to provide a better understanding of the four‐state molecular switch system in which the newly synthesized protonated merocyanines were found to play a central role. The results of this study suggest that the stability of the protonated merocyanines requires acidic conditions, as treatment with base led to the corresponding unprotonated merocyanines, which in turn spontaneously converted into photochromic closed spiropyrans.

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KW - molecular devices

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KW - UV/Vis spectroscopy

KW - X-ray diffraction

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