AZO PIGMENTS AND THEIR INTERMEDIATES - SYNTHESIS, OPTICAL-ABSORPTION,AND XEROGRAPHIC PROPERTIES OF RED-SENSITIVE AND NEAR-IR-SENSITIVE BISAZO PIGMENTS FROM 2,7-DIAMINOFLUORENONE

A series of bisazo pigments, which are designed to absorb at wavelengt hs beyond the visible region, have been synthesized by coupling 2,7-di aminofluorenone with 2-hydroxy-11H-benzo(a)carbazole-3'-carboxanilide couplers. Absorption studies show that these compounds exhibit panchro matic absorption from 450-750 nm in the solid state. The absorption ma xima lie at similar to 700 nm. Xerographic measurements reveal that ne ither electron-withdrawing nor electron-releasing substituents enhance the photosensitivity of these pigments in bilayer devices. Comparison with the structure-sensitivity relationships obtained in other bisazo pigment series suggests that the substituent effect is probably an el ectronic effect. The electronic effect is optimal when the anilide rin g in the coupler is parachlorinated. Spectral sensitivity data show th at the photoresponse coincides with the absorption spectrum. The photo response is flat from 450-750 nm with a maximum sensitivity at similar to 750 nm. More importantly, reasonable photosensitivity is demonstra ted at the GaAs wavelength, e.g., similar to 6 ergs/cm(2) at 780 nm. T his observation, along with the promising electrical cycling result, s uggests that the bisazo pigments synthesized in this work are photogen erator candidates for photoreceptors in copiers, printers, and multifu nctional printer-copiers.