H. G. O. Becker, Gabriele Weinert, H. Baumann
1993
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Journal
Journal Fur Praktische Chemie-chemiker-zeitung
Abstract
The dediazoniation of 2,5-di-(n-butoxy)-4-morpholino-benzenediazonium tetrafluoroborate (1) sensitized by zinc phthalocyanine tetrasulfomorpholid (ZnPcTSM) is studied in di-n-butylphthalate. The life-time of singlet-excited ZnPcTSM (τs = 3.0 ns) is not decreased by 1 whereas the static fluorescence at 689 nm is quenched. Thus, a ground-state complex is formed, Keq = 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), Keq = 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-state complex. Keq of the ZnPcTSM-diazonium salt complex is also obtained from quantum yields of the sensitized dediazoniation. A rather low intersystem crossing quantum yield of the complex amounting to 0.17 is deduced. ZnPcTSM is also bleached, but much weaker than expected for an oxidative electron transfer. The system works well – even under air – in dibutylphthalate micro droplets in gelatine coated on a PET-base.