Stimuli-Responsive Cyclopenta ef heptalenes: Synthesis and Optical Properties

    Authors

    E. H. G. Zadeh; A. W. Woodward; D. Richardson; M. V. Bondar;K. D. Belfield

    Comments

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    Abbreviated Journal Title

    Eur. J. Org. Chem.

    Keywords

    Cyclopenta[ef]heptalene; Stimuli response; Azulene; Electron transfer; Photoacid generator; Sensitizers; Photochromism; Natural products; Dyes; pigments; CONJUGATED OLIGOMERS; ENERGY-TRANSFER; AZULENE; CHROMOPHORES; PORPHYRIN; POLYMERS; Chemistry, Organic

    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.

    Journal Title

    European Journal of Organic Chemistry

    Issue/Number

    10

    Publication Date

    1-1-2015

    Document Type

    Article

    Language

    English

    First Page

    2271

    Last Page

    2276

    WOS Identifier

    WOS:000352110600023

    ISSN

    1434-193X

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