pi-Extended nitrofluorene-1,3-dithiole chromophore: enhancing the photoresponse of holographic materials through the balance of intramolecular charge transfer and electron affinity

The synthesis, electrochemistry, and electron absorption spectra of the novel push-pull type acceptor, 9-{[4,5-bis(hexylthio)-1,3-dithiol-2-ylidene]ethylidene}-2,4,5,7-tetranitrofluorene 3 is reported. A bathochromic shift and increased intensities of intramolecular charge transfer bands (compared to 1) are well-balanced with the electron affinity of the acceptor, which results in a pronounced increase of the photoresponse of carbazole-containing photothermoplastic optical information storage materials in the long wavelength visible and near infrared regions.