Journal of Porphyrins and Phthalocyanines J. Porphyrins Phthalocyanines 2014; 18: 899–908 DOI: 10.1142/S1088424614500709 Published at http://www.worldscinet.com/jpp/ Copyright © 2014 World Scientific Publishing Company INTRODUCTION Photodynamic therapy (PDT) in cancer treatment based on the uptaken of a photosensitizer by cancer tissue followed by photoirradiation. PDT has been used in oncology for more than 25 years and is now well established as a clinical treatment modality for various diseases, including cancer and particularly for the treatment of superficial tumours (e.g. oesophagus, bladder, and melanoma) [1]. PDT application of a photosensitizer has coupled with a few important properties such as high absorption coeffcient in the red region of visible light, long triplet state lifetimes, high quantum yield of the triplet state and triplet state of appropriate energy (≥ 95 kJ.mol -1 ) [2]. And also, hydrophilicity and specific retention of the sensitizer in the cell tissues are very important in the successful application of a sensitizer as a drug [3–6]. Hydrophilicity of the PDT drug can be achieved through sulfonation, carboxylation, or alkylation of N-pyridyl-substituted compounds [7–10]. Phthalocyanines (Pc) and their derivatives are significant photosensitizers due to strong absorption of the far-red and NIR light [11]. The photophysical properties of phthalocyanines are known to be strongly influenced by the centrally coordinated metal ion. For example, zinc- and silicon-containing phthalocyanines have exhibited promising PDT activities in preclinical and phase I clinical trials [12, 13]. These photosensitizers generally have large π conjugated systems that results in strong energy absorption and so high quantum yield, needed for efficient PDT. In terms of the singlet oxygen quantum yield, dyes such as porphyrin and its derivatives have proved to be effective photosensitizers, which possess triplet states of appropriate energy for sensitization of oxygen, but lacks practical application in view of other requirements of being a photosensitizer. On the other hand, phthalocyanine and its derivatives have been accepted as potential candidates for PDT applications [14–17]. Clinical application of phthalocyanines usually suffers Asymmetric zinc phthalocyanines substituted with a single carboxyl and triethyleneoxysulfonyl groups: synthesis, characterization and validation for photodynamic therapy Duygu Aydın Tekdas ¸, Ays ¸e G. Gürek* ◊ and Vefa Ahsen ◊ Gebze Institute of Technology, Department of Chemistry, P.O. Box 141, Gebze, Kocaeli 41400, Turkey Dedicated to Professor Nagao Kobayashi on the occasion of his 65th birthday Received 28 July 2014 Accepted 29 August 2014 ABSTRACT: This work describes modular pathway towards the synthesis of new specific unsymmetrically (AB3) zinc phthalocyanines that contains three polyoxy ethylene and monocarboxylic acid groups as photosensitizers. Their photophysical and photochemical properties are studied. General trends are described for quantum yields of fluorescence, photodegradation and singlet oxygen quantum yields of these compounds. Therefore, these novel phthalocyanines could potentially be good photosensitizers for photodynamic therapy. KEYWORDS: phthalocyanine, photochemistry, photosensitizer, photodynamic therapy, mono- carboxylated phthalocyanine. ◊ SPP full member in good standing *Correspondence to: Ayşe G. Gürek, email: gurek@gyte.edu.tr, tel: +90 262-605-3017, fax: +90 262-605-3005 J. Porphyrins Phthalocyanines 2014.18:899-908. Downloaded from www.worldscientific.com by Prof.Dr. Ayse Gul GUREK on 12/14/14. For personal use only.