Stimuli-Responsive Cyclopenta[ef]heptalenes: Synthesis and Optical Properties

Document Type

Article

Publication Date

4-1-2015

Abstract

We report the one-pot synthesis, 1D and 2D NMR characterization, and UV/Vis study of a series of cyclopenta[ef]heptalenes 4a–c that exhibit strong stimuli-responsive behavior, with a tunable energy gap as a result of perturbation of HOMO, LUMO, and LUMO+1 energies upon doping/dedoping with TFA/Et3N. The approach employed allows for the extension of conjugation at C-4 of the cyclopenta[ef]heptalene skeleton from X = H (4a) to X = CN (4b) and X = 2-thiophenyl (4c), resulting in longer absorption maxima and smaller optical energy gaps of the cyclopenta[ef]heptalenium cations 4a–c+. Additionally, in the presence of a UV-activated (< 300 nm) photoacid generator (PAG), protonation of 4c can be indirectly achieved by intermolecular photoinduced electron transfer (PeT) from the excited state of 4c to the PAG, upon which the latter undergoes photodecomposition resulting in the generation of acid. This phenomenon facilitates the use of cyclopenta[ef]heptalenes 4a–c as visible sensitizers of commercial PAGs.

Identifier

85027921493 (Scopus)

Publication Title

European Journal of Organic Chemistry

External Full Text Location

https://doi.org/10.1002/ejoc.201500059

e-ISSN

10990690

ISSN

1434193X

First Page

2271

Last Page

2276

Issue

10

Volume

2015

Grant

CBET-1517273

Fund Ref

National Science Foundation

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