Issue 3, 2004
From the journal:

New Journal of Chemistry

Halogenated silicon(iv) phthalocyanines with axial poly(ethylene glycol) chains. Synthesis, spectroscopic properties, complexation with bovine serum albumin and in vitro photodynamic activities†

Jian-Dong Huang,ab   Shuangqing Wang,a   Pui-Chi Lo,a   Wing-Ping Fong,c   Wing-Hung Kod  and  Dennis K. P. Ng*a  

* Corresponding authors

a Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
E-mail: dkpn@cuhk.edu.hk

b Institute of Research on Functional Materials, Department of Chemistry, Fuzhou University, Fuzhou, China

c Department of Biochemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China

d Department of Physiology, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China

Abstract

A new series of unsubstituted and halogenated silicon(IV) phthalocyanines with two axial poly(ethylene glycol) (PEG) chains having an average molecular weight of 550 or 750 (PEG550 or PEG750) have been synthesised by treating the corresponding silicon phthalocyanine dichloride with PEG methyl ether in the presence of NaH. The compounds have been unambiguously characterised with 1H NMR and MALDI-TOF mass spectrometry. With two bulky polymeric substituents, the compounds are essentially non-aggregated in common organic solvents. The longer PEG750 chain enhances the hydrophilicity of the phthalocyanine ring and is more effective to prevent aggregation and fluorescence quenching by Cu(OAc)2. Substitution with heavier halogen atoms on the periphery of the ring leads to a reduction in fluorescence emission and an increase in singlet oxygen quantum yield, as a result of heavy atom effect. The compounds Si(PcX8)(PEG750)2 [X = H (4b), Cl (4c), Br (4d)] are photocytotoxic towards HepG2 human hepatocarcinoma cells and J774 mouse mammary tumour cells. Although halogenation results in an increase in singlet oxygen quantum yield, the general photocytotoxicity follows the order 4b > 4d > 4c. This can be attributed to the opposite effect of aggregation, which follows the order 4a < 4b < 4c in the growth medium. The interactions of 4b–d with bovine serum albumin (BSA) have also been investigated by a fluorescence quenching method and a non-covalent conjugate of 4b and BSA has been prepared. Conjugation with BSA leads to a higher photocytotoxicity against J774 cells, which have a BSA-loving macrophage origin.

Graphical abstract: Halogenated silicon(iv) phthalocyanines with axial poly(ethylene glycol) chains. Synthesis, spectroscopic properties, complexation with bovine serum albumin and in vitro photodynamic activities

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Article information

DOI
https://doi.org/10.1039/B307934A
Article type
Paper
Submitted
11 Jul 2003
Accepted
13 Nov 2003
First published
27 Jan 2004

New J. Chem., 2004,28, 348-354

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Halogenated silicon(IV) phthalocyanines with axial poly(ethylene glycol) chains. Synthesis, spectroscopic properties, complexation with bovine serum albumin and in vitro photodynamic activities

J. Huang, S. Wang, P. Lo, W. Fong, W. Ko and D. K. P. Ng, New J. Chem., 2004, 28, 348 DOI: 10.1039/B307934A

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