Lead Phthalocyanines Research Articles

Tetrachlorosubstituted Lead Phthalocyanines: Effect of the Positions of Substituents on the Structure of Single Crystals and thin Films

Tetrachlorosubstituted Lead Phthalocyanines: Effect of the Positions of Substituents on the Structure of Single Crystals and thin Films

Dual-purpose both peripheral and non-peripheral triazole substituted ZnII, MgII and PbII phthalocyanines: Synthesis, characterization, photophysicochemical and acetylcholinesterase inhibitory properties

Both peripheral and non-peripheral 4-(3,4-dimethoxyphenethyl)-5-ethyl-2H-1,2,4-triazol-3(4H)-one substituted zinc(II), magnesium(II) and lead(II) phthalocyanines were synthesized in this paper. Techniques used to illuminate the structure of these phthalocyanines included FT-IR, MALDI TOF, UV–Vis, NMR spectroscopy. The ZnIIPcs (p/np-ZnPcs), MgIIPcs (p/np-MgPcs) and PbIIPcs (p/np-PbPcs) exhibited outstanding solubility in common organic solvents such as 1,4-Dioxane, acetonitrile, chloroform, dichloromethane, dimethylformamide, dimethylsulphoxide, ethyl acetate and tetrahydrofurane. The photophysicochemical properties of ZnIIPcs, MgIIPcs and PbIIPcs were researched in DMSO. The positions of the substituents (peripheral or non-peripheral) and the effects of the central metal ions (Zn2+, Mg2+, Pb2+) on the photophysicochemical properties were reported by comparison. The singlet oxygen quantum yield values of ZnIIPcs, MgIIPcs and PbIIPcs ranged from 0.11 to 0.78 in DMSO. The newly synthesized peripherally tetra substituted zinc(II) phthalocyanine (p-ZnPc) exhibited high singlet oxygen generation in DMSO compared to unsubstituted zinc(II) phthalocyanine used as standard. These results indicate that the (p-ZnPc) can be a candidate as photosensitizer for PDT. Besides, the inhibitory properties of the compounds were determined using the spectrophotometric method on AChE and α-glucosidase. IC50 values showed that np-MgPc has highest inhibitory actions among the tested compounds on AChE and α-glucosidase.

Design, syntheses, spectroscopic, aggregation properties of novel peripheral octa-substituted zinc(II), magnesium(II) and lead(II) phthalocyanines and investigation of their photocatalytic properties on the photooxidation of 4-nitrophenol

In the present paper, the syntheses, spectroscopic characterization, aggregation behaviours and photocatalytic properties of phthalocyanine compounds were searched. Octa-substituted phthalocyanines (ZnII (Pc-Zn), MgII (Pc-Mg) and PbII (Pc-Pb)) with eight peripheral (E)-3-(3-hydroxyphenyl)-1-(2,4,5-trimethoxyphenyl)prop-2-en-1-one groups were synthesized by cyclotetramerization. The spectral properties of these compounds were carried out that used widespread spectroscopic techniques. Later on, aggregation properties of synthesized phthalocyanines were examined in polar and apolar solvents. In addition to this, the photocatalytic activities of new synthesized metallophthalocyanines containing various central metal ions (zinc (II), magnesium (II) and lead (II)) were investigated. Three different metal centered phthalocyanines have been prepared for the photodegradation of 4-nitrophenol. In the photodegradation reactions that carried out in the photoreactor for 1 h without using any oxidant, 4-nitrophenol compound was completed with 90% (for PbII (Pc-Pb)), 56% (for ZnII (Pc-Zn)) and 12% (for MgII (Pc-Mg)) conversion from toxic species to non-harmful species and unknown intermediates. The turnover numbers were determined as 1500 for PbII (Pc-Pb), 933 for ZnII (Pc-Zn).

Determination of photophysical, photochemical and spectroscopic properties of novel lead(II) phthalocyanines

This study presents the synthesis and characterization of novel peripheral and non-peripheral tetra-2,6-dimethoxyphenoxy substituted lead(II) phthalocyanines. They were characterized by elemental analysis, IR, UV–vis, fluorescence, 1H NMR, 13C NMR and MALDI-TOF mass spectroscopic techniques, as well as thermogravimetric analysis. Their spectroscopic, photophysical and photochemical properties were studied in dimethylsulfoxide and compared with the above-mentioned properties of lead(II) phthalocyanines containing different substituents reported in the literature. Novel phthalocyanines can be good candidates as photosensitizers for photocatalytic reactions because they possess properties that are important for Type II mechanics, such as low photostability, sufficient singlet oxygen production, high solubility and non-aggregation behavior in commonly known organic solvents.

Fluorosubstituted lead phthalocyanines: Crystal structure, spectral and sensing properties

In this work, we synthesized and investigated tetra- (PbPcF4) and hexadecafluorinated (PbPcF16) lead phthalocyanines. Their single crystal structures were refined for the first time. PbPcF4 crystallizes in stacks with all molecules facing in one direction identically to the monoclinic PbPc polymorph in the tetragonal space group I4, while PbPcF16 crystallizes in the triclinic P-1 space group. Moreover, the effect of fluorosubstitution on the structural features of thin films grown by organic molecular beam deposition (OMBD), vibrational and UV–visible optical absorption spectra is discussed. Apart from this, the chemiresistive sensor response of PbPcFx (x = 0, 4, 16) films to ammonia (1–5 ppm) in dependence on fluorination degree is also studied. It was shown that the sensor response to ammonia decreases in the order of PbPcF4 > PbPcF16 > PbPc. The nature of interaction between PbPcFx and ammonia molecules was studied using DFT calculations.

Zinc(II) and lead(II) phthalocyanines bearing thiadiazole substituents: Synthesis, characterization, photophysical and photochemical properties

In this study; phthalonitrile compounds 4-((5-methyl-1,3,4-thiadiazol-2-yl)thio)phthalonitrile (4) and 3-((5-methyl-1,3,4-thiadiazol-2-yl)thio)phthalonitrile (5) were synthesized. These compounds were converted to their respective peripherally and non-peripherally tetra-substituted zinc(II) (6 and 7) and lead(II) (8 and 9) phthalocyanine derivatives. The novel phthalocyanine complexes were characterized by using different spectroscopic techniques including FT-IR, UV–Vis, 1H NMR and mass. The spectroscopic, photochemical and photophysical properties of the phthalocyanines were investigated for determination of their potential as photosensitizers for photodynamic therapy. In addition, the effects of the substituent, binding position and the variety of central metal ions in phthalocyanine core on photochemical and photophysical properties were determined.

Non-peripherally tetra substituted lead(II), nickel(II) and copper(II) phthalocyanines bearing [1,2,3] triazole moeties: Synthesis, characterization and investigation of electrochemical and spectroelectrochemical properties

In this study, the synthesis and characterization of novel [1,2,3] triazole substituted phthalonitrile compound (3) and non-peripherally tetra 3-(2H-benzo[d][1,2,3]triazol-2-yl)-4-hydroxyphenethyl methacrylate substituted lead(II) (4), nickel(II) (5) and copper(II) (6) phthalocyanine derivatives were achieved. The new compounds were characterized by using FT-IR, 1H-NMR, 13C-NMR, UV–Vis and mass spectra. The electrochemical properties of novel non-peripherally tetra [1,2,3] triazole substituted metallo phthalocyanines (4–6) was determined by cyclic voltammetry (CV) and square-wave voltammetry (SWV) for the first time in this study. The results show that all the complexes (4–6) have ligand-based diffusion controlled electron transfer properties. The color changes related to the redox processes were also recorded with in-situ electrocolorimetric measurements. When the spectral changes are compared with each other, it is clear that all complexes show Pc based electron transfer reactions. There are slight differences between the spectra of the complexes due to the different nature of the metal centers of the complexes. The electrochemical and in-situ UV–Vis spectral change of complexes (4–6) indicated that they have applicability in electrochemical technologies.

Peripherally and non-peripherally tetra-benzothiazole substituted metal-free zinc (II) and lead (II) phthalocyanines: Synthesis, characterization, and investigation of photophysical and photochemical properties

In this study, novel phthalonitrile compounds bearing 2-methylbenzo[d]thiazol-5-yloxy groups (4 and 5) and their peripherally and non-peripherally tetra-substituted metal-free (6 and 7), zinc (II) (8 and 9), and lead (II) (10 and 11) phthalocyanine derivatives were synthesized and characterized for the first time. These novel compounds showed extremely good solubility in most common organic solvents. The novel phthalocyanine compounds presented excellent results from photophysical and photochemical examinations in DMF solution. Especially, the singlet oxygen quantum yield (ΦΔ) values of the substituted zinc (II) phthalocyanines indicate that these compounds have significant potential as photosensitizers in cancer treatment by the photodynamic therapy (PDT) technique. The fluorescence quenching behaviour of these novel phthalocyanine compounds by 1,4-benzoquinone (BQ) was also examined in DMF solution.

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.

The determination of photophysical and photochemical parameters of novel metal-free, zinc(II) and lead(II) phthalocyanines bearing 1,2,4-triazole groups

In this study the synthesis and characterization of novel phthalonitrile compound (3) and its metal-free (4), zinc(II) (5), and lead(II) (6) phthalocyanines bearing four 4-(4-methoxyphenylethyl)-5-propyl-2,4-dihydro-3H-1,2,4-triazol-3-one groups at peripheral positions were synthesized for the first time. These novel compounds were fully characterized by FT-FT-IR, 1H NMR, UV–vis and MALDI-TOF mass spectroscopic techniques. Their photochemical and photophysical properties were also investigated in N,N-dimethylformamide solutions. In addition, the effect of 4-(4-methoxyphenylethyl)-5-propyl-2,4-dihydro-3H-1,2,4-triazol-3-one groups as substituents and central metal ions (without metal, zinc(II) or lead(II)) in the phthalocyanine cavity on these properties were also compared. The studied zinc(II) or lead(II) phthalocyanines can be potential Type II photosensitizers for photodynamic therapy in cancer applications because these phthalocyanines showed good singlet oxygen generation and appropriate photodegradation.

Electrochemical and spectroelectrochemical properties of new metal free, nickel(II), lead(II) and zinc(II) phthalocyanines

The new metal free, nickel(II), lead(II) and zinc(II) phthalocyanines containing 2-[2-(4-allyl-2-methoxyphenoxy)ethoxy]ethoxy groups were synthesized and structurally characterized by using IR, 1H NMR, 13C NMR, UV–vis and elemental analysis spectral data. Redox properties of the complexes were determined with voltammetric and in situ spectroelectrochemical measurements in different electrolytic systems, tetrabutylammonium perchlorate (TBAP) dissolved dichloromethane (DCM) and dimethylsulfoxide (DMSO). All complexes gave two reversible reduction couples in the cathodic sides of the voltammograms in TBAP/DCM. While two oxidation processes were observed for all complexes in DCM, these processes were recorded as broad and split waves. All of the redox processes of the complexes shifted to the negative potentials and behaved more reversible in TBAP/DMSO electrolyte. Due to the narrow anodic potential window of DMSO, only one oxidation process was recorded in DMSO, while third reduction processes could be observed at more negative potentials for all complexes. Changing of the metal center of the complexes caused to shifting of the redox processes due to the different effective nuclear charge on the metal ions of the complexes. It can be easily concluded that the results of the voltammetric and in situ spectroelectrochemical supported the proposed structure of the complexes.

Enhanced nonlinear optical properties of octa-substituted lead and cadmium phthalocyanines when embedded in poly(bisphenol A carbonate) as thin films

This work presents photophysical and nonlinear optical properties of a novel Cd 2,3-[octakis{4-tert-butylphenoxyphthalocyanine}] (CdOtBPPc) and compare them with those of Pb 2,3-[octakis{4-tert-butylphenoxyphthalocyanine}] (PbOtBPPc). For both the CdOtBPPc and PbOtBPPc, third order imaginary susceptibility and second order hyperpolarizability values were found to be within the limit set for good optical limiters. The Pcs were embedded in poly (methyl methacrylate) (PMMA) and poly(bisphenol A carbonate) (PBC) as thin films. The optical limiting values of the Pcs once embedded in film were found to be greatly improved and the limiting fluence of each film was well below the maximum threshold. Both PbOtBPPc and CdOtBPPc showed better optical limiting when embedded in PBC compared to PMMA. CdOtBPPc shows better nonlinear optical behavior than PbOtBPPc in solution and as thin films, even though the former is aggregated in solution.

Applications of lead phthalocyanines embedded in electrospun fibers for the photoinactivation of Escherichia coli in water

Lead (II) pyridyloxyphthalocyanine (PbTpyPc) and its quaternized form (PbTepyPc) were synthesized and the photophysical behavior examined. Low fluorescence quantum yields (ΦF) of 0.01 and 0.02 were observed for PbTepyPc and PbTpyPc, respectively. The singlet oxygen quantum yields (ΦΔ) were 0.60 and 0.68, for PbTepyPc and PbTpyPc, respectively using DPBF as a quencher in DMF. Singlet oxygen production of the embedded sensitizers in electrospun fiber were quantified using ADMA and were found to be ΦΔ = 0.41 and ΦΔ = 0.21 for PbTepyPc and PbTpyPc, respectively. Photodynamic inactivation of Escherichia coli (E. coli) with the quaternized photosensitizer at 5 μM, totally inactivated the E. coli (with log CFU = 10 decrease). Only 0.4 log CFU decrease was obtained with PbTpyPc. The embedded non-quaternized photosensitizer (PbTpyPc) was less active on the gram negative bacteria but the quaternized photosensitizer (PbTepyPc) was effective towards inactivation of E. coli.

Synthesis and characterization of some octaalkyl substituted lead phthalocyanines and unexpected variations in lead lability arising from the position of substituents and their chain length

The preparation of some peripherally substituted (2,3,9,10,16,17,23,24) and non-peripherally substituted (1,4,8,11,15,18,22,25) octaalkyl lead(II) phthalocyanines with different alkyl chain lengths (6, 7, 8 or 9 carbons) is described and a comparison of some of their properties reported. X-ray structure analyses of the isomeric peripheral and non-peripheral octakis(octyl)phthalocyaninato lead(II) compounds reveal a greater degree of distortion of the ligand ring system from planarity in the former derivative. The series of peripherally substituted octaalkyl lead(II) phthalocyanines exhibit columnar liquid crystal behavior whereas the non-peripherally substituted isomers do not. The lability of the lead ion was investigated using 1 H NMR spectrometry under a specific set of conditions (8.8 × 10-4 M solutions of the phthalocyanine in d8-toluene containing d4-acetic acid 2.06 × 10-5 M). All the compounds underwent acid catalyzed demetalation at rates dependent upon the location of the substituents and, more surprisingly, the chain length of the alkyl groups. Under these conditions the lead ion within each of the peripherally substituted octaalkyl lead phthalocyanines was more labile than that in the non-peripherally substituted isomer.

Novel organosoluble metal-free and metallophthalocyanines bearing triazole moieties: Microwave assisted synthesis and determination of photophysical and photochemical properties

The synthesis and characterization of new peripherally metal-free (4), nickel (5), zinc (6), cobalt (7), copper (8) and lead (9) phthalocyanines bearing tetra-2-(4-(4-methoxybenzylamino)-5-oxo-3-p-tolyl-4, 5-dihydro-1H-1, 2, 4-triazol-1-yl)ethoxy groups have been described for the first time in this study. These new phthalocyanine compounds have been characterized by several spectral methods such as FT-IR, 1H NMR, 13C NMR, electronic spectroscopy, mass spectra and elemental analyses. The thermal stabilities of these new phthalocyanines were determined by thermogravimetric analysis. The photophysical (fluorescence quantum yields and fluorescence lifetimes) and photochemical (singlet oxygen generations and photodegradation quantum yields) properties of metal-free (4), zinc (6) and lead (9) phthalocyanines were studied in dimethylsulfoxide (DMSO). The fluorescence quenching behavior of metal-free (4), zinc (6) and lead (9) phthalocyanines was also investigated.

Liquid crystalline octasubstituted lead(ii) phthalocyanines: effects of alkoxy and alkylthio substituents on film alignment and electrical properties

Octasubstituted lead(II) phthalocyanines containing alkylthio- and alkoxy- groups in peripheral positions have been synthesized and characterized using 1H and 13C NMR, UV-Vis, IR and mass spectroscopies as well as elemental analysis. The mesogenic properties of the octasubstituted lead(II) phthalocyanines have been investigated by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction. The sandwich structures ITO/PbPc/In were prepared to investigate the J(V) characteristics of thin films of these molecules. The dissimilar behavior of the films before and after heat-treatment is expected to result in changing the alignment inside the columnar stacking of the molecules in the films.

Tetraoctylthio- and tetraoctyloxy-substituted lead phthalocyanines: Synthesis, characterization, liquid-crystalline properties, and thin film studies

Abstract

Synthesis, photophysical and photochemical properties of highly soluble phthalocyanines substituted with four 3,5-dimethylpyrazole-1-methoxy groups

The synthesis and characterization of new peripherally tetra-3,5-dimethylpyrazole-1-methoxy substituted metal-free ( 4), zinc ( 5), nickel ( 6), cobalt ( 7), copper ( 8) and lead ( 9) phthalocyanines are described for the first time in this study. The photophysical (fluorescence quantum yields and fluorescence lifetimes) and photochemical (photodegradation and singlet oxygen quantum yields) properties of metal-free ( 4), zinc ( 5) and lead ( 9) phthalocyanines are studied in dimethylsulfoxide (DMSO). Nickel ( 6), cobalt ( 7) and copper ( 8) phthalocyanines ( 6–8) did not evaluate for this purpose due to transition metal and paramagnetic behavior of central metals in the phthalocyanine cavity. The fluorescence quenching behavior of metal-free ( 4), zinc ( 5) and lead ( 9) phthalocyanines are also investigated. The fluorescence emissions of these phthalocyanines are effectively quenched by 1,4-benzoquinone in DMSO.

Synthesis, H- or J-type aggregations, electrochemistry and in situ spectroelectrochemistry of metal ion sensing lead(II) phthalocyanines

We report, in this study, peripherally 3- and 4-substituted functionalized ionophore ligands ( 1– 3) and their α- and β-tetra polyalcohol substituted lead(II) phthalocyanines M{Pc[S–CH(C 3H 7)(C 2H 5OH)] 4} ( 7, 9 and 11) and M{Pc[S–C 6H 12(OH)] 4} ( 8, 10 and 12) which are a mixture of different isomers. The complexes have been fully characterized by elemental analysis, FT-IR, 1H NMR, 13C NMR, MS (MALDI-TOF) and UV–Vis spectral data. These complexes induced H-type (face-to-face fashion) or J-aggregate (edge-to-edge) dimers when titrated with AgNO 3 or Na 2PdCl 4 in a THF–MeOH solution. Cyclic and square wave voltammetry studies showed that the complexes gave three one-electron ligand-based reductions and two one-electron oxidation couples having diffusion controlled mass transfer character. Assignments of these redox couples were confirmed by spectroelectrochemical measurements. The observation of split Q bands, which are characteristic spectral behavior of metal-free phthalocyanines, indicates demetallization of the complexes during the spectroelectrochemical measurement under the applied potentials. The types of the substituents on the ring of the phthalocyanines affect the demetallization process of the complexes.

The synthesis and characterization of novel mesomorphic octa- and tetra-alkylthio-substituted lead phthalocyanines and their films

Two novel mesomorphic octakis and tetrakis (alkylthio)-substituted phthalocyanines of Pb(II) were synthesized and characterized using NMR, UV–Vis, FT-IR and mass-spectrometry. The mesogenic properties of these new materials forming columnar-hexagonal mesophases were studied by differential scanning calorimetry, optical microscopy and X-ray diffraction. Visible absorption spectroscopy provided evidence of thermally induced molecular reorganization in films. IR spectroscopy and density functional theory calculations were used to study the preferential orientation of molecules relative to the substrate surface. The intense IR bands in the spectra of the lead phthalocyanines were assigned with the aid of quantum chemical computations. The observed increase in the intensity of the out-of-plane modes in the IR spectra correlate with an average preferential edge-on orientation of the molecules on the substrate surface in the film. The current-voltage characteristics of films before and after thermal treatment were also measured. The results confirmed the film ordering proposed on the basis of the IR and DFT studies.