Jian-Dong Huang
Corresponding author, tel: +86 591-22866337, fax: +86 591-28306766.
College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350002, China
Xiong-Jie Jiang
College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350002, China
Xiao-Min Shen
College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350002, China
Qing-Qing Tang
College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350002, China

Received 15 September 2008
Accepted 13 April 2009

Two novel axial-disubstituted silicon(IV) phthalocyanines (compounds 1 and 2) have been prepared by introducing paracetamol (a common antipyretic analgesic) or its isomer 4-hydroxyphenylacetamide at the axial positions of silicon(IV) phthalocyanine, respectively. Their photophysical and biological properties have been examined. Both compounds are highly soluble and exhibit very similar absorption spectra in N, N-dimethylformamide, which is typical for non-aggregated phthalocyanines. Both compounds are photocytotoxic against HT29 human colon adenocarcinoma cells. Compound 2 shows a very high in vitro photodynamic activity, with the IC₅₀ value down to 15 nM. In contrast, compound 1 exhibits a much lower in vitro photodynamic activity toward HT29 cells, which can be attributed to its higher aggregating trend in the biological medium and lower singlet oxygen quantum yield.

silicon phthalocyanine; photodynamic therapy; photosensitizer; cancer cell