Enhanced triplet state parameters for zinc carboxy phenoxy phthalocyanine following conjugation to ascorbic acid: Effects of adsorption on single walled carbon nanotubes

Abstract Zinc phthalocyanine bearing four ascorbic acid units (formed via ester bond between zinc carboxy phenoxy phthalocyanines and ascorbic acid) was synthesized and characterized using different spectroscopic methods. The complex (with or without ascorbic acid) was further adsorbed onto single walled carbon nanotubes (SWCNTs) and further characterized using Raman spectroscopy, X-ray diffractometry, transmission electron microscopy and thermogravimetric analysis. The photophysical properties of the complexes were studied. The synthesized complex showed better photophysical properties when compared to the carboxy phenoxy phthalocyanines alone, this is evident in the increase of the triplet quantum yields ( Φ T ), triplet life-times ( τ T ) and singlet oxygen quantum yields ( Φ Δ ). The zinc phthalocyanines bearing ascorbic acid showed improved triplet life-times even in the presence of SWCNTs.