Novel synthesis of poly(benzoin) and poly(benzil). Characterization and application as photosensitizer materials

New photoactive polymers containing benzoin or benzil groups have been prepared by condensation of terephthalaldehyde. The influence of the alkali metal ions and solvents used upon the progress of polycondensation and yield of poly(benzoin) Systematic name: Poly(1,4‐phenylene‐1‐hydroxy‐2‐oxoethylene). were studied. Oxidation of this polymer by nitric acid or ammonium nitrate in acetic acid afforded the corresponding poly(benzil) Systematic name: Poly(1,4‐phenylene‐1,2‐dioxoethylene). in quantitative yield. The resulting polymers were confirmed by elemental analysis, IR, 1H NMR and UV/visible spectral data, and characterized using viscometry, DTA measurements, thermogravimetric and X‐ray analysis. The photosensitizing property of the prepared polymers was detected by fluorescence. It was found that irradiation of poly(benzoin) in DMSO solution at 285 nm causes yellow fluorescence whereas poly(benzil) does not display fluorescence at the same excitation wavelength. Moreover, the use of poly(benzil) as photosensitizer material in the photochemical cleavage of thiourea and its derivatives was also studied.