Oxidation of Pollutants Catalyzed by Metallophthalocyanines

Synthesis, Spectral, and Fluorescence Studies of Fluorophenyl Methoxy Substituted Nickel Phthalocyanine Complex

The synthesis, characterization, spectral, fluorescence properties of bis(4-fluorophenyl)-methoxy substituted nickel phthalocyanine were reported for the first time. The new compound has been characterized by elemental analysis, UV-Vis, FT-IR, 1H-NMR and mass spectra. The aggregation behaviour of this compound was investigated in the different solvent and concentrations of in CHCl3. Phthalocyanine complex did not show any aggregations. The fluorescent properties of the compound in five different solvents such as CHCl3 CH2Cl2 THF, DMF, DMSO were explained. Phthalocyanine complex gave the highest fluorescence quantum yield in CHCl3 and the lowest fluorescence quantum yield in DMSO.

Photochemical generation and reactivity of a new phthalocyanine-manganese-oxo intermediate

The first phthalocyanine-manganese-oxo intermediate was successfully generated by visible-light photolysis of chlorate or nitrite manganese(III) precursors, and its reactivity towards organic substrates was kinetically probed and compared with other related porphyrin-metal-oxo intermediates.

Oxidative N-Dealkylation of N,N-Dimethylanilines by Non-Heme Manganese Catalysts

Non-heme manganese(II) complexes [(IndH)MnIICl2] (1) and [(N4Py*)MnII(CH3CN)](ClO4)2 (2) with tridentate isoindoline and pentadentate polypyridyl ligands (IndH = 1,3-bis(2′-pyridylimino)isoindoline; N4Py* = N,N-bis(2-pyridylmethyl)-1,2- di(2-pyridyl)ethylamine) proved to be suitable to catalyze the oxidative demethylation of N,N-dimethylaniline (DMA) with various oxidants such as tert-butyl hydroperoxide (TBHP), peracetic acid (PAA), and meta-chloroperoxybenzoic acid (mCPBA), resulting N-methylaniline (MA) as a main product with N-methylformanilide (MFA) as a result of a free-radical chain process under air. The effect of electron-donating and electron-withdrawing substituents on the aromatic ring on the relative reactivity of the substrates and on the product composition (MA/MFA) was also studied and showed a significant impact on the catalytic N-demethylation reaction. Based on the Hammett correlation with ρ = −0.38 (PAA), −0.45 (mCPBA), and −0.63 (TBHP) for 1 and ρ = −0.38 (PAA) and −0.37 (mCPBA) for 2, an electrophilic intermediate is suggested as the key oxidant. Furthermore, the spectral investigation (UV-Vis) resulted in direct evidence for the formation of a high-valent oxomanganese(IV) and a transient radical cation intermediate, p-Me-DMA•+, suggesting that the initial step in the manganese-catalyzed oxidations is a fast electron-transfer between the amine and the high valent oxometal species. The mechanisms of the subsequent steps are discussed.

Oxidative degradation of toxic organic pollutants by water soluble nonheme iron(iv)-oxo complexes of polydentate nitrogen donor ligands

The ability of four mononuclear nonheme iron(iv)-oxo complexes supported by polydentate nitrogen donor ligands to degrade organic pollutants has been investigated. The water soluble iron(ii) complexes upon treatment with ceric ammonium nitrate (CAN) in aqueous solution are converted into the corresponding iron(iv)-oxo complexes. The hydrogen atom transfer (HAT) ability of iron(iv)-oxo species has been exploited for the oxidation of halogenated phenols and other toxic pollutants with weak X-H (X = C, O, S, etc.) bonds. The iron-oxo oxidants can oxidize chloro- and fluorophenols with moderate to high yields under stoichiometric as well as catalytic conditions. Furthermore, these oxidants perform selective oxidative degradation of several persistent organic pollutants (POPs) such as bisphenol A, nonylphenol, 2,4-D (2,4-dichlorophenoxyacetic acid) and gammaxene. This work demonstrates the utility of water soluble iron(iv)-oxo complexes as potential catalysts for the oxidative degradation of a wide range of toxic pollutants, and these oxidants could be considered as an alternative to conventional oxidation methods.

Metallophthalocyanines as Catalysts in Aerobic Oxidation

The first remarkable property associated to metallophthalocyanines (MPcs) was their chemical “inertness”, which made and make them very attractive as stable and durable industrial dyes. Nevertheless, their rich redox chemistry was also explored in the last decades, making available a solid and detailed knowledge background for further studies on the suitability of MPcs as redox catalysts. An overlook of MPcs and their catalytic activity with dioxygen as oxidants will be discussed here with a special emphasis on the last decade. The mini-review begins with a short introduction to phthalocyanines, from their structure to their main features, going then through the redox chemistry of metallophthalocyanines and their catalytic activity in aerobic oxidation reactions. The most significant systems described in the literature comprise the oxidation of organosulfur compounds such as thiols and thiophenes, the functionalization of alkyl arenes, alcohols, olefins, among other substrates.

Synthesis and Characterization of New Imidazole Phthalocyanine for Photodegradation of Micro-Organic Pollutants from Sea Water

In this study, a series of new metal phthalocyanines with imidazole function MPc(Imz) (M: Cd, Hg, Zn and Pd) were synthesized to improve the photocatalyst performances. All physical properties such as total energy, HOMO, LUMO energies of MPc(Imz), as well as their vibrational frequencies have been determined by DFT method using B3LYP theory level at 6-311G (d, p) and sdd basis set. The gap of energy level between work function (WF) of ITO and LUMO of PdPc(Imdz) was 1.53 eV and represents the highest barrier beneficial to electron injection compared to WF of ZnPc(Imz), HgPc(Imz), and CdPc(Imz). Furthermore, the PdPc(Imdz) thin films on indium tin oxide (ITO) glass were prepared by spin coating and vacuum evaporation technique, and were characterized by X-ray diffraction (XRD), surface electron morphology (SEM), atomic force microscopy (AFM), and UV–Vis spectroscopy. The photocatalytic activity of the ITO/glass supported thin films and degradation rates of chlorinated phenols in synthetic seawater, under visible light irradiation were optimized to achieve conversions of 80–90%. Experiments on synthetic seawater samples showed that the chloride-specific increase in photodegradation could be attributed to photochemically generated chloride radicals rather than other photoproduced reactive intermediates [e.g., excited-state triplet PdPc(Imz) (3PdPc(Imz)*), reactive oxygen species]. The major 2,3,4,5-Tetrachlorophenol degradation intermediates identified by gas chromatography-mass spectrometry (GC/MS) were 2,3,5-Trichlorophenol, 3,5-dichlorophenol, dichlorodihydroxy-benzene and 3,4,5-trichlorocatechol.

A simple and facile bioinspired catalytic strategy to decolorize dye wastewater by using metal octacarboxyphthalocyanine particles

To explore the simple, facile, environmental friendly and low cost catalytic technique to decolorize harmful dye contaminants in solution and understand the mechanism is an interesting and practical research. In this paper, we provide a highly efficient and convenient method for fast decolorization of dyes (methylene blue and rhodamine B) in aqueous solution catalyzed by iron octacarboxyphthalocyanine (FeOCPc) or cobalt octacarboxyphthalocyanine (CoOCPc). Compared to the traditional methods, our method is very simple. The 30 mg/L methylene blue could be decolorized almost absolutely less than 30 min just by dispersing FeOCPc powders into the dye solution. The decolorization of rhodamine B at high concentration (30 mg/L) could be achieved to 100% decolorization degree less than 20 min in the presence of FeOCPc and tert-butyl hydroperoxide (BuOOH). Moreover, the ESR and HPLC-MS measurement were performed to determine the active radicals and various intermediates in decolorization processes and the possible catalytic mechanism was proposed. It is noted that both FeOCPc and CoOCPc catalysts show the different catalytic oxidation behaviors depending on the oxidant (O₂ or BuOOH). Our investigation provides a novel, low cost and convenient strategy to purify the environmental pollutions.

The efficient, fast and facile decolorization of organic dyes homogeneously catalyzed by iron octacarboxylic phthalocyanine

To remove the harmful dye contaminants via an efficient, facile and low energy consumption route is a grave challenge in current chemical industry. Though the great progresses of TiO₂ photocatalysis and enzymatic degradation have been witnessed, the strategy for satisfying the above requirements is still worth exploring. Herein, we develop a biomimetic catalysis strategy for the fast decolorization of organic dyes catalyzed by iron octacarboxylic phthalocyanine (FeOCPc) complexes assisted with tert-butyl hydroperoxide (BuOOH). Methyl orange (MO) and methylene blue (MB) were used as the model pollutants and experimental results show that the decolorization degree of 25 mg/L MO could achieve 100% within 20 min and 80% for 25 mg/L MB within 30 min. The molar ratio for FeOCPc/MO and FeOCPc/MB is 0.146 and 0.142, respectively. Interestingly, other than the high-valent iron-oxygen active species, tert-butyl peroxyl radicals and hydroxyl radicals were detected as the active species generated during the catalytic oxidation by the electron paramagnetic resonance (EPR) measurement. This work not only provides a distinctive biomimetic catalysis system of FeOCPc-BuOOH for the fast bleaching of dye pollutants, but also proposes the new insight on a mechanism based on the cooperation catalysis of iron-oxygen active species, tert-butyl peroxyl radicals and hydroxyl radicals.

An Efficient One-Pot Protocol for the Synthesis of Substituted 3,4-Dihydropyrimidin-2(1H)-ones Using Metallophthalocyanines (MPcs) as Potent Heterogeneous Catalysts: Synthesis, Characterization, Aggregation and Antimicrobial Activity

In this study, novel phthalonitrile 3 and their corresponding metal-free 4 and metallophthalocyanine derivatives 5–7 bearing 2-isopropenyl-4-methoxy-1-methylbenzene groups were synthesized and characterized. 3,4-Dihydropyrimidinones have been synthesized by a modified Biginelli-type reaction with various metallophthalocyanines 5–7 as catalysts. Compared to the classical Biginielli reaction, the new method has the advantages of good yield and short reaction time. Among the various metallophthalocyanines studied, cobalt (II)-phthalocyanine was found to be most active for this transformation. The newly prepared compounds were characterized using elemental analyses, MS, IR, ¹H/¹³C-NMR and UV-Vis spectroscopy. In addition; the 3,4-dihydropyrimidinones (DHPMs) 8–12 were investigated for antimicrobial activities and revealed good activity. The minimum inhibitory concentration (MIC) was determined by the microdilution technique in Mueller-Hinton broth. The MICs were recorded after 24 hours of incubation at 37 °C. These results are promising, showing these compounds are biologically active.

Nonlinear Optical Materials for the Smart Filtering of Optical Radiation

The control of luminous radiation has extremely important implications for modern and future technologies as well as in medicine. In this Review, we detail chemical structures and their relevant photophysical features for various groups of materials, including organic dyes such as metalloporphyrins and metallophthalocyanines (and derivatives), other common organic materials, mixed metal complexes and clusters, fullerenes, dendrimeric nanocomposites, polymeric materials (organic and/or inorganic), inorganic semiconductors, and other nanoscopic materials, utilized or potentially useful for the realization of devices able to filter in a smart way an external radiation. The concept of smart is referred to the characteristic of those materials that are capable to filter the radiation in a dynamic way without the need of an ancillary system for the activation of the required transmission change. In particular, this Review gives emphasis to the nonlinear optical properties of photoactive materials for the function of optical power limiting. All known mechanisms of optical limiting have been analyzed and discussed for the different types of materials.

Why Does 2,3,5,6-Tetrachlorophenol Generate the Strongest Intrinsic Chemiluminescence among All Nineteen Chlorophenolic Persistent Organic Pollutants during Environmentally-friendly Advanced Oxidation Process?

We found recently that intrinsic chemiluminescence (CL) could be produced by all 19 chlorophenolic persistent organic pollutants during environmentally-friendly advanced oxidation processes. Interestingly and unexpectedly, the strongest CL was produced not by the most-highly chlorinated pentachlorophenol (PCP), but rather by the less chlorinated 2,3,5,6-tetrachlorophenol (2,3,5,6-TeCP), one of the three tetrachlorophenol (TeCPs) isomers. However, it remains unclear what is the underlying molecular mechanism. Here we show that not only chlorinated quinoid intermediates, but more interestingly, semiquinone radicals were produced during the degradation of the three TeCPs and PCP by Fenton reagents, and the type and yield of which were found to be well correlated with CL generation. We propose that hydroxyl radical-dependent formation of more tetrachlorinated quinoids, quinone-dioxetanes and electronically excited carbonyl species might be responsible for the exceptionally strong CL production by 2,3,5,6-TeCP as compared to PCP and its two isomers. This is the first report showing the critical role of quinoid intermediates and semiquinone radicals in CL generation from polychlorinated phenols and Fenton system. These new findings may have broad chemical and environmental implications for future studies on remediation of other halogenated persistent aromatic pollutants by advanced oxidation processes.

Photocatalytic Deposition of Hydroxyapatite onto a Titanium Dioxide Nanotubular Layer with Fine Tuning of Layer Nanoarchitecture

A new effective method of photocatalytic deposition of hydroxyapatite (HA) onto semiconductor substrates is proposed. A highly ordered nanotubular TiO2 (TNT) layer formed on titanium via its anodization is chosen as the photoactive substrate. The method is based on photodecomposition of the phosphate anion precursor, triethylphosphate (TEP), on the semiconductor surface with the following reaction of formed phosphate anions with calcium cations presented in the solution. HA can be deposited only on irradiated areas, providing the possibility of photoresist-free HA patterning. It is shown that HA deposition can be controlled via pH, light intensity, and duration of the process. Energy-dispersive X-ray spectroscopy profile analysis and glow discharge optical emission spectroscopy of HA-modified TNT prove that HA deposits over the entire TNT depth. High biocompatibility of the surfaces is proven by protein adsorption and pre-osteoblast cell growth.

Dendrimeric magnetic nanoparticle cores with Co-phthalocyanine tags and their application in the synthesis of tetrahydrobenzo[b]pyran derivatives

A novel magnetically recoverable nanocatalyst was synthesized and used for the synthesis of tetrahydrobenzo[b]pyran derivatives under mild conditions.

Purification of avian biological material to refined keratin fibres

Keratin derived from chicken feather fibres (CFFs) has many potential applications that are constrained by the quality and pathogen content after purification treatment.