Optical Spectroscopy and Photochemistry of Thin Films of Propylmethylpolyazine
Bradford C. Sherman, William B. Euler, Electrical, Optical, and Magnetic Properties of Organic Solid State Materials, Materials Research Society Symposium Proceedings, L. Y. Chiang, A. F. Garito, D. J. Sandman, eds., 1992, 247, 675 – 679
Abstract
Propylmethylpolyazine, [N=C(R1)–C(R2)=N]x, (R1 = CH3, R2 = CH2CH2CH3) is an organic-soluble linear conjugated polymer. The ultraviolet spectrum of thin films of this material shows two peaks at about 280 nm and 320 nm. These absorptions are ascribed to transitions from filled valence bands to the same empty conduction band. Oxidative doping of this polymer with iodine gives spectra that are consistent with the generation of bipolarons. Irradiation of pristine thin films with 300 nm light causes a two step photoprocess to occur. The first step happens during the first hour of irradiation and if the film is left in the dark is completely reversible. The second step takes considerably longer to complete (more than 12 hr of irradiation) and is irreversible. The UV spectrum and FTIR spectrum of the step one photoproduct suggest that the imine bond is undergoing an E to Z isomerization photochemically that reverses in the dark. The step two product is probably due to a cycloaddition reaction.