Metal-free Phthalocyanine Derivatives Research Articles

Synthesis, characterization and photophysicochemical properties of peripherally tetra-substituted phthalocyanines bearing carboxylic acid moieties

In the present study, peripherally tetra-substituted metal-free (H2Pc), Mg(II) (MgPc) and In(III)CI (InPc) phthalocyanine compounds containing carboxylic acid moieties were synthesized and characterized by various spectroscopic techniques. Photophysical, photochemical and aggregation properties of these compounds, which are show good solubility in DMSO, DMF and THF, were investigated. Aggregation behaviors of these phthalocyanines were investigated using DMSO and DMF in different concentrations. The photophysicochemical properties including fluorescence spectra and quantum yield, singlet oxygen generation and photodegradation behavior were researched in DMSO and DMF to clarify the usability of these compounds as a photosensitizers. In addition, the effects of the presence and absence of metal ion on photochemical and photophysical properties of these phthalocyanines are also examined. The metallo phthalocyanines (Mg(II) and In(III)CI) showed high singlet oxygen generation efficiency compared to metal-free phthalocyanine derivative. According to singlet oxygen generation efficiency, we can say that the presence of metal ion on phthalocyanine ring increases singlet oxygen generation. The results show that these compounds may have potential to be used as a photosensitizers in photodynamic therapy (PDT) applications.

Investigation of photophysicochemical properties of non-peripherally tetra-substituted metal-free, Mg(II), Zn(II) and In(III)CI phthalocyanines

In the present work, the synthesis, characterization, photophysicochemical and aggregation properties of non-peripherally tetra-substituted metal-free (H2Pc), Mg(II) (MgPc), Zn(II) (ZnPc), and In(III)CI (InCIPc) phthalocyanines containing tetra (2,3-dihydro-1,4-benzodioxin-2-ylmethoxy) moieties were reported. The spectroscopic techniques were applied to characterize these phthalocyanines. The synthesized phthalocyanines exhibit very good solubility in many common solvents and their aggregation behaviors were examined using DMSO at different concentrations. The photophysicochemical (Fluorescence spectra, fluorescence, singlet oxygen and photodegradation quantum yield) properties were investigated in DMSO to detect the usability of the mentioned phthalocyanines as photosensitizers. Besides, the effects of the absence and presence of metal ion on their photophysicochemical properties are also researched. The metallo phthalocyanines (Mg, Zn and In) generated higher singlet oxygen than metal-free phthalocyanine derivative. According to singlet oxygen efficiency, the presence of metal ion on phthalocyanine ring increases singlet oxygen production. The results show that these phthalocyanines may be suitable candidates as photosensitizers in photodynamic therapy.

New peripherally and non-peripherally tetra-substituted metal-free, magnesium(II) and zinc(II) phthalocyanine derivatives fused chalcone units: Design, synthesis, spectroscopic characterization, photochemistry and photophysics

Chalcone containing new peripherally and non-peripherally tetra-substituted metal-free and metallophthalocyanine derivatives were designed and synthesized (Schemes 1 and 2). The structures of chalcone-phthalocyanines were characterized by a combination of common spectroscopic techniques such as LC–MS/MS (for new phthalonitrile derivative 3a), ground state electronic absorption spectra (for all new phthalocyanines), 1H NMR spectroscopy (for all new compounds), 13C NMR spectroscopy (for new phthalonitrile and metal-free phthalocyanine derivatives), Fourier transform infrared (FT–IR with ATR sampling accessory) (for all new compounds) and MALDI–TOF mass spectral data (for all new phthalocyanines and new phthalonitrile derivative 3b) as well as elemental analysis. In addition, the effects of the presence of different kinds of metal ions [magnesium(II) or zinc (II)] in the phthalocyanine core and the effects of the introduction of (3,4-dimethoxyphenyl)-3-oxoprop-1-en-1-yl)phenoxy units at both peripheral and non-peripheral positions of the phthalocyanine skeleton on photophysical and photochemical properties of the new substituted magnesium(II) and zinc(II) phthalocyanines have also been examined in DMF. The obtained results were compared with each other and with unsubstituted magnesium(II) and zinc(II) phthalocyanines. All newly synthesized phthalocyanines are soluble in common organic solvents as well as no type of aggregation was observed in these solvents. Moreover; the chalcone fused magnesium(II) and zinc(II) phthalocyanines also showed excellent fluorescence properties. Specifically, the new non-peripheral zinc(II) and magnesium(II) chalcone-phthalocyanines have the remarkable potential to be used as Type II photosensitizers for the treatment of cancer in PDT owing to their good singlet oxygen and appropriate photodegradation quantum yields. Since chalcones and their derivatives show a broad range of biological and pharmaceutical activities, these products are promising candidates for various applications, particularly as photosensitizers for photodynamic therapy in combination with fluorescence imaging.

Barrierless On-Surface Metal Incorporation in Phthalocyanine-Based Molecules

On-surface metalation of metal-free phthalocyanine derivatives is a simple and solvent-free way to fabricate MPc compounds. Using phthalocyanine (H2Pc) molecules on Ag(111) as an example, we investigated the atomic-scale mechanisms of on-surface metalation processes using first-principles calculations based on density functional theory. When the molecules are deposited on a substrate first, we find that transition-metal atoms, except for Zn, drop directly from the vacuum into the molecule’s cavity without an energy barrier and bond with the inner four nitrogen atoms, with the two pyrrolic H atoms still in place. Subsequently, the two H atoms transfer to the substrate by overcoming small energy barriers and diffuse away. The substrate participates in the reaction by hybridization. In the alternative process, when metal atoms are adsorbed first on the surface and the H2Pc molecules are then added, the metal atoms diffuse into the cavity of the molecule via the molecule–surface interface by overcoming finite...

Metal-free, zinc(II) and lead(II) phthalocyanines functioning with 3-(2H-benzo[d][1,2,3]triazol-2-yl)-4-hydroxyphenethyl methacrylate groups: Synthesis and investigation of photophysical and photochemical properties

In this study, the synthesis and characterization of 3-(2H-benzo[d][1,2,3]triazol-2-yl)-4-hydroxyphenethyl methacrylate substituted novel phthalonitrile compound and its peripherally substituted zinc(II) lead(II) and metal-free phthalocyanine derivatives were performed for the first time. This novel compounds were characterized by obtained data from general spectroscopic methods such as FT-IR, 1H NMR, 13C NMR and mass. The photophysical and photochemical properties of these phthalocyanines were investigated in N,N-dimethylformamide solutions for determination of their photosensitizing abilities in photocatalytic applications such as photodynamic therapy. The lead(II) phthalocyanine complex did not produce any fluorescent in N,N-dimethylformamide because of the heavy atom effect of bigger lead atom. The fluorescence quantum yields of studied zinc(II) and metal-free phthalocyanines were found to quite higher than unsubstituted zinc(II) phthalocyanine due to substitution of the phthalocyanine skeleton. The influence of substituent and variety of the central metal ions on spectroscopic, photophysical and photochemical properties were also determined and compared.

Microwave-Assisted Synthesis of Some Metal-Free Phthalocyanine Derivatives and a Comparison with Conventional Methods of their Synthesis

Synthesis of metal-free 2,9(10),16(17),23(24)-tetra(3,5- dimethylphenoxy) phthalocyanine, 2,9(10),16(17), 23(24)-tetra(4- tert-butylphenoxy) phthalocyanine, and 2,9(10),16(17),23(24)-tetra(3,5- di-tert-butyl-4-hydroxyphenyl) phthalocyanine was carried out via microwave irradiation. Furthermore, pentanol and lithium were used for the first time in the synthesis of metal-free phthalocyanine under microwave irradiation as a solvent and a base-catalyst, respectively. The microwave irradiation experiments were performed in a MARS5 with a CEM XP-1500 vessel. In addition, these compounds were obtained with conventional heating procedures to compare them with those obtained with microwave irradiation. The compounds were characterized by elemental and spectroscopic analysis, including UV-Vis, H NMR, FT-IR, and MALDI-TOF mass data. In particular, both methods were compared in terms of reaction parameters and product yields. In addition, we first performed the synthesis of phthalonitriles as an initial material at room temperature, which is a slight modification of that reported in the literature. These Pc-compounds had high thermal stability, which was determined at 520 °C (midpoint), 549 °C, and 400 °C, respectively, as a maximum weight loss temperature. Consequently, the microwave irradiation method provided nearly the same or higher product yields in a very short period of time. These results suggest that the microwave irradiation method was more useful than the conventional method due to shorter reaction time and energy savings.

Rapid and efficient synthesis of metal-free phthalocyanine derivatives

Metal-free phthalocyanine derivatives have been synthesized in very short times with high yields in the presence of 1,1,3,3-tetramethylguanidinium trifluoroacetate (TMGT) as an ionic liquid or tetrabutylammonium bromide (TBAB) as a phase transfer reagent under both classical heating conditions and using microwave irradiation. The best results were obtained with ionic liquid. Both the ionic liquid and phase transfer reagent can be recycled for subsequent reactions and reused without appreciable loss of efficiency.

Molecules of synthesized phthalocyanine as a material for the detection of 2,4-toluene diisocyanate (TDI)

Various numbers of LB monolayers of a metal-free phthalocyanine derivative, A410H 2Pc, have been deposited onto ultrasonically cleaned quartz substrates with platinum interdigitated electrodes. Similar devices i.e. those with the same number of LB layers, show the same response characteristics in the presence of 35 ppb (0.035 ppm) toluene diisocyanate (TDI)—a toxic substance used in the production of plastics and found in certain types of paint. The response times of the LB devices studied so far have been calculated to be about 40s. The electrical properties of evaporated films of a metal-free phthalocyanine derivative, α-H 2Pc, and those of the A410H 2Pc LB films have been found to be similar. The response time for the evaporated films has been found to be much less that that for the LB films. Although a direct comparison cannot be made between the LB and evaporated films, in this case, results suggest that devices fabricated from evaporated films will be much faster at detecting the presence of TDI than devices fabricated from LB films.