Elsevier

Polyhedron

Volume 100, 4 November 2015, Pages 1-9
Polyhedron

Metal ion sensing soluble α or β tetrasubstituted gallium and indium phthalocyanines: Synthesis, characterization, photochemistry and aggregation behaviors

https://doi.org/10.1016/j.poly.2015.07.035Get rights and content

Abstract

This paper reports on the synthesis and characterization of peripherally and non-peripherally tetra-substituted gallium and indium phthalocyanines (3, 4, 5 and 6) containing 6-hydroxyhexylthio group. Synthesized compounds have been characterized by elemental analysis, FT-IR, 1H NMR, 13C NMR, MALDI-TOF and UV–Vis spectral data. Atomic force microscopy was also used as complementary techniques to investigate the morphology. Absorption spectral changes of the functional MPcs during addition of Ag(I) and Pd(II) soft-metal ions were evaluated by UV–Vis spectroscopy with monomer–dimer formation. All the same, photochemical properties and photophysical properties (Fluorescence quantum yields and flouresans behavior) of these phthalocyanines were performed. General trends focus on fluorescence, photodegradation and singlet oxygen quantum yields of these compounds in dimethylformamide. The nature of the substituent and solvent effect on the photophysical and photochemical parameters of the substituted phthalocyanines (3, 4, 5 and 6) are also reported.

Graphical abstract

This paper reports on the synthesis and characterization of α or β tetra-substituted gallium and indium phthalocyanines. Synthesized compounds have been characterized by elemental analysis, FT-IR, 1H NMR, 13C NMR, MALDI-TOF and UV–Vis spectral data. Atomic force microscopy was also used as complementary techniques. Also, photochemical and photophysical properties of these phthalocyanines were performed.

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Introduction

Phthalocyanines are planar aromatic macrocycles consisting of four isoindole units [1]. Due to their excellent stability in a wide variety of chemical environments chemical and thermal stability and flexible preparation methods, substituted phthalocyanines (Pcs) has been studied for especially recent years [2]. Metalphthalocyanines (MPcs) have received a great deal of attention due to their interesting electrical, optical and structural properties, followed by numerous application for example chemical sensors [3], [4], photoconductors [5], electrochromic display [6], catalysis [7], liquid crystal [8], nanotechnology [9] and especially, photosensitizers for photodynamic cancer therapy (PDT) [10], [11]. Phthalocyanines (Pc) have been proved as highly promising photosensitizers for PDT (photodynamic therapy) due to their intense absorption in the red region of the visible light [12]. PDT technique based on the administration of a photosensitiser that must be condense more tumor tissues than regular tissues. This is followed by illumination of the tumor with visible light in a wavelength range matching the absorption spectrum of the photosensitizer [13]. The resulting photodynamic reactions give rise to singlet oxygen (1O2) and to other active oxygen species that lead to tumor destruction. The PDT efficiency can be improved with the use of photosensitizers that absorb strongly red light above 700 nm, where tissue exhibits optimal transparency. Up to now, several new generation of potential sensitisers for PDT have been developed and investigated; among these phthalocyanines have been found to be as highly promising due to high absorbance coefficient in the region of 650–680 nm [10].

Unsubstituted phthalocyanines are insoluble and tend to aggregate (π–π stacking interactions) in common organic solvents. this insolubility is restricted its very well research. Nevertheless, phthalocyanines can be modified in a number of ways by incorporation of substituents in their peripheral (β) and non-peripheral (α) positions and solubility of phthalocyanines can be improved. This modification increases the π-electron density and makes solvation easier [14]. Due to low solubility of unsubstituted phthalocyanines are not investigated in chemical and physical properties very well, Therefore, the solubility of Pcs is very important and soluble phthalocyanine synthesis are main purpose [15]. These type approaches to increase solubility, reduce aggregation, increasing its excited state lifetimes and improving its cellular uptake in aqueous media are of extremely importance in PTD studies [16]. Tetra substituted phthalocyanines are usually more soluble than octa-substituted phthalocyanines because of the formation of constitutional isomers and the high dipole moment that results from the unsymmetrical arrangement of the substituents at the periphery [17].

Phthalocyanines have a high trend to aggregate in aqueous solutions particularly [18]. The peripheral and/or nonperipheral substituted phthalocyanines could be form two types of aggregations which affect on electronic and optical properties. One type is face-to-face H-aggregation [19] and other type is side-to-side J-aggregation [20]. Generally, phthalocyanine aggregation results in a decrease in intensity of the Q-band corresponding to the monomeric species, simultaneously a new, broader and blueshifted or red-shifted band is seen to increase in intensity. This shift to lower wavelengths indicates to H-type aggregation among the phthalocyanine molecules. In rare cases, red-shifted bands have been observed corresponding to J-type aggregation of the phthalocyanine molecules [20].

Phthalocyanines bearing thia-oxo functionalities show optical changes when they bind Ag (I) and Pd (II) ions, while crown-attached phthalocyanines are well suited to bind alkaline and alkaline earth metal ions [21].

Substitution at non-peripheral positions gives rise to red shifting of the Q-band of MPcs according to the substitution at the peripheral positions [22], [23] and the presence of electron donating sulfur groups on Pc leads to the red shifting of the Q-band to more longer wavelengths as a result of the electron-donating thioether substituents when compared with those of unsubstituted and alklyl or O-substituted derivatives [24].

Due to their heavy diamagnetic nature and axially substituted capacity Ga(III) and In(III) metals have been chosen as central atoms. It is known that axial substitution can introduce a dipole moment perpendicular to macrocycle, and via steric effect it can alter the spatial relationship between neighboring molecules [25]. Also are known that photophysical properties of the phthalocyanine are influenced by the presence and nature of the central metal ion. Phthalocyanine complexes with diamagnetic ions, such as Zn2+, Al3+, and Ga3+, both high triplet yields and long lifetimes have [26].

First of all this paper is concerned with the synthesis of ligand 4-(6-hydroxyhexylthio)-phthalonitrile and 3-(6-hydroxyhexylthio)-phthalonitrile were prepared according to the procedure reported in the literatüre [27], [28] and then, its peripherally and nonperipherally β- α-substituted MPcs, M[Pc(β-SC6H12OH)4] {M = Ga(III)(3), In(III)(4) }, M[Pc(α-SC6H12OH)4] {M = Ga(III)(5), In(III)(6)} are described, and also their soft metal ions (Ag(I) and (Pd(II)) binding properties are investigated and evaluated. In addition, Surface morphologies of novel type phthalocyanines were performed by AFM without interaction and after interaction with soft metal ions (Ag(I) and (Pd(II). Finally, photochemical properties (Singlet oxygen quantum yields and photodegradation quantum yields) and photophysical properties (Fluorescence quantum yields and flouresans behavior) of α or β tetra-substituted phthalocyanines were investigated.

Section snippets

Materials and methods

Chloroform (CHCl3), tetrahydrofuran (THF), 4-nitrophthalonitrile, 3-nitrophthalonitrile, GaCI3, InCI3 were purchased from Merck and Alfa Aesar and used as received. All other reagents were obtained from Fluka, Aldrich and Alfa Aesar Chemical Co. and used without purification. The purity of the products was tested in each step by TLC(SiO2, CHCl3/MeOH and THF/MeOH). FT-IR spectrophotometer recorded on Perkin Elmer Two FT-IR spectrophotometer where samples were dispersed in KBr. Chromatography was

Synthesis and characterization

In common, substituted phthalocyanines are prepared by cyclotetramerization of α or β substituted 1,3-diimino-1H-isoindoles or phthalonitriles. 2(3),9(10),16(17),23(24)-Tetra-substituted phthalocyanines can be synthesized from β-substituted phthalonitriles on the other hand 1(4),8(11),15(18),22(25)-tetra-substituted phthalocyanines are synthesized from α-substituted analogues [27], [28].

In this study, ligands, 4-(6-hydroxyhexylthio)-phthalonitrile (1) and 3-(6-hydroxyhexylthio)-phthalonitrile (2

Conclusion

We have presented the synthesis and characterization of peripherally or nonperipherally (β- or α-) substituted M[Pc(β-SC6H12OH)4] {M = Ga(III)(3), In(III)(4)}, M[Pc(α-SC6H12OH)4] {M = Ga(III)(5), In(III)(6)} metallopthalocyanines. Structures of the new compounds were characterized by elemental analysis, FT-IR, 1H NMR, 13C NMR, MALDI-TOF, UV–Vis spectral data as standart method and also AFM was used as complementary techniques to investigate of surface morphology. The soft metal ions (Ag(I) and

Acknowledgment

We thanks, The Research Fund of Sakarya University (Project no: 2013-02-04-049 and 2014-02-04-011) and TUBİTAK (Project no: 114Z448).

References (45)

  • W. Wu et al.

    Dyes Pigm.

    (2011)
  • F. Yakuphanoglu et al.

    Physica B

    (2007)
  • Y.S. Krasnov et al.

    Solid State Ionics

    (2009)
  • T.V. Basova et al.

    Dyes Pigm.

    (2014)
  • M. Durmuş et al.

    Inorg. Chem. Commun.

    (2007)
  • E. Kirbaç et al.

    J. Organomet. Chem.

    (2014)
  • M.N. Sibata et al.

    Eur. J. Pharma. Sci.

    (2004)
  • E.N. Kaya et al.

    J. Organomet. Chem.

    (2014)
  • A. Günsel et al.

    Synthesis

    Polyhedron

    (2010)
  • Z. Biyiklioglu

    Synth. Met.

    (2014)
  • H. Li et al.

    Tetrahedron

    (2009)
  • M. Sevim et al.

    Dyes Pigm.

    (2014)
  • M. Kandaz et al.

    Polyhedron

    (2000)
  • D. Arican et al.

    Electrochim. Acta

    (2013)
  • M.N. Yarasir et al.

    Polyhedron

    (2007)
  • M.N. Yarasir et al.

    Polyhedron

    (2007)
  • M. Kandaz et al.

    Polyhedron

    (2009)
  • A. Ogunsipe et al.

    J. Photochem. Photobiol. A: Chem

    (2005)
  • I. Seotsanyana-Mokhosi et al.

    Photochem. Photobiol. A: Chem

    (2001)
  • A. Ogunsipe et al.

    J. Photochem. Photobiol. A: Chem

    (2005)
  • A. Ogunsipe et al.

    J. Mol. Struct.

    (2003)
  • M. Durmus et al.

    Spectrochim. Acta A

    (2008)
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