Water soluble {2-[3-(diethylamino)phenoxy]ethoxy} substituted zinc(II) phthalocyanine photosensitizers Dilek Çakır a , Cem Göl b , Volkan Çakır a , Mahmut Durmuş b , Zekeriya Bıyıklıoğlu a,n , Halit Kantekin a a Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, 61080 Trabzon, Turkey b Gebze Institute of Technology, Department of Chemistry, PO Box 141, Gebze, 41400, Kocaeli, Turkey article info Article history: Received 1 September 2014 Received in revised form 11 October 2014 Accepted 20 October 2014 Available online 29 October 2014 Keywords: Phthalocyanine Water soluble Photodynamic therapy Photosensitizer BSA binding DNA interaction abstract The new peripherally and non-peripherally tetra-{2-[3-(diethylamino)phenoxy] ethoxy} substituted zinc phthalocyanines (2a and 3a) were synthesized by cyclotetramerization of phthalonitrile derivatives (2 and 3). 2-[3-(diethylamino)phenoxy] ethoxy group was chosen as substituent because the quaterni- zation of the diethylamino functionality on the structure of this group produced water soluble zinc phthalocyanines (2b and 3b). The water solubility is very important for many different applications such as photosensitizers in the photodynamic therapy of cancer because the water soluble photosensitizers can be injected directly to the body and they can transport to cancer cells through blood stream. The new compounds were characterized by using elemental analysis, UV–vis, IR, 1 H NMR, 13 C NMR and mass spectroscopies. The photophysical and photochemical properties of these novel photosensitizer compounds were examined in DMSO (both non-ionic and ionic complexes) and in PBS (for ionic complexes) solutions. The investigation of these properties is very important for the usage of the compounds as photosensitizers for PDT because determination of these properties is the first stage of potential of the compounds as photosensitizers. The bovine serum albumin (BSA) and DNA binding behaviour of the studied water soluble zinc (II) phthalocyanines were also investigated in PBS solutions for the determination of biological activity of these compounds. & 2014 Elsevier B.V. All rights reserved. 1. Introduction Phthalocyanines (Pcs) are the synthetic analogues of naturally occuring porphyrin family. Phthalocyanines are known as multi way dye staffs and are being applied in variety of industrial and medical fields such as nonlinear optical devices [1], optical data storage [2,3], solar cell [4,5], electrochromic displays [6,7], chemical sensors [8,9], gas sensors [10,11], liquid crystals [12,13], semiconductors [14], photocatalysts [15]. One of the new and important practical applications of metallophthalocyanines containing diamagnetic metals such as Zn 2 þ , Al 3 þ , Ga 3 þ is their use as photosensitizers for photodynamic therapy (PDT) of cancer due to their long triplet lifetimes and high efficiency of photogeneration of cytotoxic singlet oxygen [16–20]. Unsubstituted phthalocyanines are practically insoluble in common organic solvents and water, which restrict the investiga- tion and application of phthalocyanines. Therefore, the solubility of phthalocyanines has been improved by introducing crown ethers, alkyl, alkoxy, phenoxy, alkylthio, tertiary butyl, macrocyclic groups and amino substituents to their peripheral positions [21–29]. Phthalocyanine compounds can be quaternized through amine groups on substituents to reduce aggregation and increase their solubility and biological efficacy [30–32]. Water solubility plays very important role for a potential photosensitizer [30] in PDT applications. The advantages of MPcs bearing cationic substituents over those with neutral and anionic substituents are numerous [33] such as improving water solubility, prevent aggregation [34], efficiency as PDT agents [35], enhancing cell uptake [36] and selectively localized in the cell mitochondria and causing to apoptosis [37]. The target of our ongoing research is to synthesis of water- soluble zinc phthalocyanine photosensitizers as potential PDT agents. For this reason, in this study, we have investigated photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen and photodegradation quantum yields) properties of newly synthesized peripherally and non- peripherally tetra-substituted non-ionic (2a and 3a) and cationic Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jlumin Journal of Luminescence http://dx.doi.org/10.1016/j.jlumin.2014.10.044 0022-2313/& 2014 Elsevier B.V. All rights reserved. n Corresponding author. Tel.: þ90 462 377 36 64; fax: þ90 462 325 31 96. E-mail address: zekeriya_61@yahoo.com (Z. Bıyıklıoğlu). Journal of Luminescence 159 (2015) 79–87