Unprecedented chemosensing behavior of novel tetra-substituted benzimidazole zinc(II) phthalocynine for selective detection of Bi 3+ ion: Synthesis, characterization and ROS generation Azeem Ullah a , Faheem Shah b, ⁎, Imran Khan a , Muhammad Anwar a , Kiramat Shah c , Munira Taj Muhammad a , Farid Ahmad c a Fujian Institute of Research on the Structure of Matter, CAS, 155 Yang Qiao West road, Fuzhou, Fujian 350002, China b Department of Chemistry, COMSATS Institute of Information Technology, Abbottabad 26020, Pakistan c H.E.J. Research Institute of Chemistry, University of Karachi, Karachi 75270, Pakistan abstract article info Article history: Received 5 May 2017 Received in revised form 19 October 2017 Accepted 1 November 2017 Available online 10 November 2017 In this work, synthesis of novel symmetrical 4-(2-bromo-4-(5-bromo-1H-benzo[d] imidazol-2-yl) phenoxy) tetra substituted zinc phthalocyanine has been reported. The novel benzimidazole zinc phthlocynine compound (3) has been characterized by MALDI-TOF MS, FT-IR, UV–vis, and 1 H NMR spectroscopy. This new compound 3 displayed excellent selectivity towards Bi 3+ ion in the presence of other competitive ions including Ca 2+ , Cd 2+ , Co 2+ Cu 2+ , Fe 3+ , Hg 2+ , Sn 2+ , Mg 2+ , Na + , Ni 2+ and Pb 2+ respectively. Upon addition of Bi 3+ into the so- lution of compound 3 in DMSO, dramatic change was observed in the Q- and the B-bands in UV–visible spectra as a result of donor acceptor interactions. Reactive oxygen species (ROS) were also studied using 2,7- dichlorofluorescin diacetate (DCFH-DA) a fluorescent probe which is converted to highly fluorescent dichlorofluorescein (DCF) in the presence of ROS. This property of non-aggregating zinc phthalocyanine is prom- ising as a photosensitizer in photodynamic therapy of cancer. © 2017 Published by Elsevier B.V. Keywords: Bi 3+ Chemosensor Reactive oxygen species Zinc phthalocyanine 1. Introduction Phthalocyanines (Pcs) have attracted considerable attention be- cause of increasing demands for wide potential applications due to ex- tensive 18π electron aromatic system. Pc is one of the important class of tetra pyrrole derivatives showing a wide range of potential applica- tions such as liquid crystals [1], electronic devices [2], photodynamic therapy [3], gas and chemical sensors [4,5], electrochromic and electro- luminescent displays [6], non-linear optics [7], photovoltaic [8] and semiconductors [9] in addition to their traditional use as dyes and pig- ments. In view of these extensive applications, researchers inspired to synthesize new analogues for determining new structure base proper- ties relationship. There is a need of modification in the skeletal structure on phthalocynine to enhance the chemical, physical, absorption and electronic properties of phthalocyanines such as solubility, optical and electrochemical potentials. The electronic, steric effects of substituents and the presence of heavy atom on Pc ring cause shifting of the Q- band to longer wavelengths and can influence the orbital and molecular structure of the metallo-phthalocyanine (MPc) complexes, which di- rectly modify the electrochemical properties and thus affect main physicochemical properties [10,11]. Synthesis of suitably functionalized phthalocyanines containing heavy metals, halogens and diamagnetic groups that are known to promote intersystem crossing is of interest [12]. The nature and position of substituents are vital in relation to sol- ubility, aggregation in solution and also physical and photo-physical properties of phthalocynine. The introduction of heavy atom on the phthalocyanine rings subsequently leads to high singlet oxygen quan- tum yield. Phthalocyanines containing diamagnetic metals or metal- loids such as Zn 2+ , Al 3+ , Ga 3+ have long triplet state lifetimes (st N 200 ms) and generate singlet oxygen with high quantum yields [13]. This high quantum yield effect lead to deep tissue penetration in PDT treatment approach [14]. Zinc(II) Pc complexes have attracted much in- terest because of their appreciably long triplet lifetimes [15,16]. MPc derivatives are an excellent functional materials exhibit inter- esting chemical and physical properties. These potential applications have been studied extensively in many areas such as material science, non-linear optics, catalysis, and liquid crystals [2,6]. Phthalocyanines, also shows some exceptional catalytic properties such as oxidation of olefins, alkanes, alcohols, aromatic compounds have received consider- able attention as potential catalysts, as well [17,18]. However, intermo- lecular interaction between Pc molecules results in a disadvantageous outcome as known aggregation that hinder their technological applica- tions [16]. Unsubstituted Pcs have very low solubility in common Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 192 (2018) 188–193 ⁎ Corresponding author. E-mail address: fshah@ciit.net.pk (F. Shah). https://doi.org/10.1016/j.saa.2017.11.002 1386-1425/© 2017 Published by Elsevier B.V. Contents lists available at ScienceDirect Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy journal homepage: www.elsevier.com/locate/saa