ELECTRONIC SPECTROSCOPY OF POLY(PROPYLMETHYLAZINE)

Poly(propylmethylazine) ([N=C(R1)-C(R2)=N]x, R1 = CH3, R2 = CH2CH2CH3, PMPAZ) and a permethylpolyazine (MMPAZ)-PMPAZ copolymer series with v arying amounts of propyl substitution has been studied by UV-vis spect roscopy in solution and UV-vis-NIR as thin films and 12-doped thin fil ms. The presence of the propyl group allows for limited solubility in some organic solvents but does not affect the approximate C2h symmetry of the conjugated pi backbone indicative of substantial sigma-pi sepa rability. Due to the two imine bonds in the repeat unit the electronic manifold contains two high-lying filled bands and two low-lying empty bands. The pristine polymers all exhibit a pi --> pi multiplet arisi ng from the conjugated azine moiety with maxima observed approximately at 280 and 320 nm arising from transitions to the lower energy conduc tion band. A bandgap of 3.0 eV has been assigned by extrapolation of t he low-energy band edge and an approximate energy diagram of the pi ma nifold is proposed. The iodine-doped PMPAZ thin-film spectrum is domin ated by the I3- signature and is accompanied by a pronounced vacuum-UV band edge while the pi --> pi multiplet is diminished and no longer discernible. Compensation with ammonia regenerates the conjugated azin e manifold.