Skip to main content

Free Content Photochemistry of photochromic benzopyrans studied by timeresolved absorption spectroscopy

Download Article:
 Download
(PDF 86.0576171875 kb)
 

Abstract:

Photochromic reactions of 2H-benzopyrans have been extensively studied to design new materials for commercial applications such as optical memories. Photochromism of 2H-benzopyrans proceeds from a C–O bond cleavage of the colorless closed form to give the colored open forms, which can thermally revert back to the original closed form. From time-resolved absorption spectroscopy, the ring opening of 2H-benzopyrans, 2,4-diphenyland 2,2,4-triphenyl-2H-benzopyran, is found to occur via the excited singlet state within 2 ps to produce vibrationally excited open forms in the ground electronic state. In the subnanosecond to submillisecond time domain, several decay components are observed. These components are assigned to respective stereoisomers with respect to two double bonds and one single bond of the open enone forms. As revealed from pump-laser power dependencies of the yields of the open forms, the photocleavage of the benzopyran molecules gives at first only the open forms revertible to the closed form by a single-bond rotation, and the photoexcitation of the first generated open forms gives rise to other open forms that need a doublebond rotation for reversion to the original closed form. Such a two-step two-photon photochromism can be expected to have a wide range of application.

Document Type: Research Article

DOI: https://doi.org/10.3184/003685001783239041

Affiliations: Institute of Molecular Science, Myodaiji, Okazaki 444-8585, Japan

Publication date: 2001-05-15

More about this publication?
  • SCIENCE PROGRESS has for over 100 years been a highly regarded review publication in science, technology and medicine. Its objective is to excite the readers' interest in areas with which they may not be fully familiar but which could facilitate their interest, or even activity, in a cognate field. Science Progress commissions world authorities to contribute articles on the most interesting, important and meaningful topics - ranging from cosmology to the environment - and ensures that they are presented for the most effective use of those in both academia and industry.

    Truly, Science Progress publishes an eclectic mix of articles that no library can afford to be without.

  • Editorial Board
  • Information for Authors
  • Subscribe to this Title
  • Ingenta Connect is not responsible for the content or availability of external websites
  • Access Key
  • Free ContentFree content
  • Partial Free ContentPartial Free content
  • New ContentNew content
  • Open Access ContentOpen access content
  • Partial Open Access ContentPartial Open access content
  • Subscribed ContentSubscribed content
  • Partial Subscribed ContentPartial Subscribed content
  • Free Trial ContentFree trial content
Cookie Policy
X
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more