DEDIAZONIATION OF 2,5-DI(N-BUTOXY)-4-MORPHOLINO-BENZENEDIAZONIUM TETRAFLUOROBORATE SENSITIZED BY ZINC PHTHALOCYANINE TETRASULFOMORPHOLIDE (ZNPCTSM) IN DI-N-BUTYL PHTHALATE

The dediazoniation of 2,5-di-(n-butoxy)-4-morpholino-benzenediazonium tetrafluoroborate (1) sensitized by zinc phthalocyanine tetrasulfomorp holid (ZnPcTSM) is studied in di-n-butylphthalate. The lifetime of sin glet-excited ZnPcTSM (tau(s) = 3.0 ns) is not decreased by 1 whereas t he static fluorescence at 689 nm is quenched. Thus, a ground-state com plex is formed, K(eq) = 1730 M-1 showing an absorption band at 714 nm. A similar complex is formed with mono-n-butylphthalate being present if di-n-butylphthalate was not distilled in a good vacuum (1 torr), K( eq) = 1545 M-1. The decay of the triplet state in the presence of 1 is adequately treated as a reaction from the triplet-excited ground-stat e complex. K(eq) of the ZnPcTSM-diazonium salt complex is also obtaine d from quantum yields of the sensitized dediazoniation. A rather low i ntersystem crossing quantum yield of the complex amounting to 0.17 is deduced. ZnPcTSM is also bleached, but much weaker than expected for a n oxidative electron transfer. The system works well - even under air - in dibutylphthalate micro droplets in gelatine coated on a PET-base.