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A number of substituted manganese phthalocyanines PcMn have been synthesized from the corresponding phthalonitriles with rather good yields (up to 67%) and high purity. All complexes were characterized by elemental analysis, electronic absorption spectra, and some of them by redox potentials. Three coordination forms — PcMn(II), PcMn(III)X and [LPc...
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... can be obtained depending on the substituent nature [17]. The same conclusion follows from the results of the electrochemical investigations of substituted PcMn for the last 7 years (some of them see in Table 3). ...
Similar publications
Three new substituted manganese phthalocyanines (PcMns), wich are water-soluble, have been synthesized with good yields (70–80%) and high purity. Pyridiniummethyl- and cholinylsubstituted phthalocyanines have been obtained from the chloromethylsubstituted PcMns, while octacarboxysubstituted complex has been synthesized from metal-free octacarboxyph...
Citations
... The electrocatalytic activity of these MPcs has been reported to follow the following order depending on the central metal: Fe 2+ > Co 2+ > Mn 2+ > Ni 2+ ≈ Cu 2+ [4]. In this work, manganese was used as the transition metal of choice since manganese phthalocyanines (MPc) have excellent redox properties required for electrochemical sensing [5,6]. The central metal in manganese phthalocyanines (MnPc) has a variety of oxidation states (Mn(I), Mn(II), Mn(III), and Mn(IV)), which results in MnPc complexes exhibiting rich electrochemical profiles. ...
... Equation (5) is proposed since the reduction of the Mn(III)Pc to [Mn(II)Pc] − by nitrite is known [12]. Equation (6) is suggested since the [Mn(II)Pc] − is oxidised back to Mn(III)Pc [12]. ...
This work investigates the use of manganese phthalocyanines (MnPcs) in the electrochemical detection of nitrite. These are two Schiff base derivatives: tetrakis 4-(4-thio-thiophene-2-ylmethanamino) phthalocyaninato Mn(III)Cl (2) and tetrakis 4-(3-(pyrrolidine-1-yl)propan-1-amino)phthalocyaninato Mn(III)Cl (3) and one aldehyde: tetrakis(4-formylphenoxy)phthalocyaninato Mn(III)Cl (1). The MnPc complexes were adsorbed onto the glassy carbon electrode surface using the drop-dry method and used as electrocatalysts to detect nitrite. Nitrite oxidation peak potentials obtained using cyclic voltammetry ranged between 0.70 and 0.84 V. Detection limits as low as 0.16 µM and sensitivity values as high as 276 µMmM⁻¹ were obtained through the use of chronoamperometry. The Schiff base MnPcs 2 and 3 exhibited better nitrite detection properties (in terms of limit of detection and sensitivity) than their aldehyde precursor (1).
Graphical Abstract
... Although, synthesis and electrochemistry of numerous MPcs have been reported in literature, most of these reported complexes have M II Pc core, such as Co II , Zn II , Cu II , and Ni II due to the ease synthesis, purification and high yield of these type complexes [1,19,20]. MPcs having higher oxidized metal center are not much in number and have potentiality for more applications because of their redox richness [21][22][23][24][25][26][27][28][29]. Thus, in this paper, we reported the synthesis and spectral, and electrochemical characterizations and the electrocatalytic and the electro sensing applications of In III ClPc, Mn III ClPc, and Ti IV OPc bearing (3,5-bis(trifluoromethyl)phenyl)ethynyl substituents. ...
A series of [PcMnL2]SbF6 complexes (Pc = phthalocyanine) was synthesized and structurally characterized by stripping the chloride from PcMnCl with AgSbF6 in o-dichlorobenzene and adding a range of donor ligands (L = THF, pyridine, p-dimethylaminopyridine (DMAP), Ph3PO, N-methylimidazole (MeIm), MeCN) to the resulting solution. Addition of or exposure to water where L = heterocyclic amines yielded μ-oxo complexes of the form [PcMnL]2O, which were structurally characterized for L = DMAP and MeIm. The [PcMnL2]SbF6 complexes have an increased solubility in organic solvents, where the axial ligands inhibit the characteristic ring π-π aggregation of PcM complexes. A variety of colours were observed (blue/green to red/purple), with Q-band absorptions (excluding the μ-oxo species) spanning from 715-761 nm and LMCT-bands from 497-574 nm. The combination of the ligand-induced absorption shifts coupled with their relative intensities in the visible region is responsible for the observed colour range and illustrates that facile ligand exchange is a useful tool in producing materials with a variety of colours from PcMnCl.
Thin films of Manganese Phthalocyanine (MnPc) were thermally deposited onto glass substrates and were vacuum annealed at different temperatures in steps of 50 K. Variation of the optical band gap with annealing temperature was studied for the MnPc thin films from its absorption spectra. Structural properties of the annealed MnPc thin films studied using X Ray diffraction technique yielded grain size for each annealing temperature. Cyclic voltammetry studies showed that all the MnPc thin films changed their color between green-purple-green under different redox potentials and the films annealed at 423 K had the highest electrochemical reversibility and coloration efficiency compared to the other annealed films.
The preparation and structural characterization of a series of chromium phthalocyanine complexes with multiple metal and ring oxidation states was achieved using PcCr(II) (1) (Pc = phthalocyanine) or PcCr(II)(THF)2 (1·THF2) as starting material. The reaction of soluble 1·THF2 with Br2 or I2 gave the PcCr(III) halide complexes PcCrX(THF) (X= I/I3, Br) (3, 4). Treatment of 1 with one-half equivalent of PhIO or air generated the dinuclear [PcCr(THF)]2(μ-O) (5), while the addition of one equivalent of AgSbF6 to 1 resulted in oxidation to THF-solvated octahedral [PcCr(III)(THF)2]SbF6 (6). The reduction of 1 with three sequential equivalents of KEt3BH resulted in the isolation of [K(DME)4][Pc3-Cr(II)] (7), [K(DME)4]2[Pc4-Cr(II)] (8) and [K6(DME)4][Pc4-Cr(I)]2 (9) respectively. The reduced products are deep purple in colour, with visible absorption maxima between 500~580 nm. The ring-reduced complexes 7 and 8 are monomeric, while 9 is a 1-D chain of dinuclear [PcCr]2 units with intercalated K+ cations and supported by Cr-Cr interactions of 2.988(2) Å. Addition of four equivalents of KC8 resulted in the demetallated product PcK2(DME)4 (10), which has a 1-D chain structure. The isolation and structural characterization of new PcCr complexes spanning five oxidation states, including rare examples of crystalline reduced Pc-ring species emphasizes the broad redox-activity and stability of phthalocyanine-based complexes.
Conventional electroanalytical methods: voltammetry, amperometry, and so on are excellent methods to determine concentrations, to drive thermodynamic parameters of a system (peak potential, free energy change, entropy, etc.), and to clarify redox reaction mechanisms. However, these techniques are not themselves enough to identify unknown intermediates and products formed during a redox reaction. A combinatory technique, spectroelectrochemistry (SEC) can solve this problem. Since SEC allows for a more complete analysis of electron transfer reactions and complex redox processes. Although SEC techniques have been well developed during the last few decades, their applications in different fields have recently become more widespread (Gale in Spectroelectrochemistry: theory and practice. Springer, New York, 1988 [1]). This chapter is meant to serve a guide where SEC can clarify the understanding of the redox reactions through identifications of the intermediates and products of various phthalocyanines. Phthalocyanines (Pcs) are one of the most prominent ligand types in coordination chemistry. They are used as dyes, photosensitizers, catalysts, sensors, and electrochromic materials, which are well generally related with their versatile redox properties and their outstanding roles in these areas are well documented (Sorokin in Chem Rev 113(10):8152–8191, 2013; Kobayashi and Konami in Phthalocyanines: properties and applications. VCH, New York, 1996; Milaeva et al. in the phthalocyanines, properties and applications. Wiley, New York, pp. 162–227, 1992 [2–4]). One of the most distinctive properties of Pcs is the rich redox behaviors, up to four reductions and two oxidation reactions. On the other hand many of the metal ions in the core of Pcs [in metallophthalocyanines (MPcs)] and some substituents can give extra redox reactions between the electron transfer reactions of Pc ring. A clear assignment of such redox reactions in MPcs is not easy to make with only voltammetric analyses. For a profound understanding of the electrochemical behaviors of MPcs, e.g., interaction of Pc ring and metal centers or axial, peripheral, and/or nonperipheral substituents, electrochemical and spectroscopic and of course SEC experiments are in general carried out (Ou et al. in Macroheterocycles 4(3):164–170, 2011; Alemdar et al. in Polyhedron 28(17):3788–3796, 2009; Sekota and Nyokong in Polyhedron 15(17):2901–2908, 1996; Arici et al. in Electrochim Acta 87:554–566, 2013; Burat et al. in Electroanal 24(2):338–348, 2012; Simicglavaski et al. in J Electrochem Soc 134(3):C130, 1987 [5–10]). This chapter will report on how SEC can contribute to the assignments of different classes of MPc complexes. Since there has been extensive investigation on the electrochemical properties of MPcs, this chapter focuses on the generalization of SEC responses of the similar types of the complexes. We classified MPcs as metal-free phthalocyanines (H2Pcs), metallophthalocyanines bearing redox inactive metal centers (MPcs-RIAM), metallophthalocyanines bearing redox active metal centers (MPcs-RAM), metallophthalocyanines carrying redox active substituents (MPcs-RAS), and sandwich metallophthalocyanines (MPc2s) due to the characteristic SEC response differences between these groups of complexes.
The synthesis of novel, symmetrical, tetrasubstituted manganese phthalocyanine complexes bearing 4 hexylthio, 2',3',4',5',6'-pentafluorobenzyloxy, 2',3',5',6'-tetrafluoro-4'-hexylthio-benzyloxy, and 2',3',5',6'-tetrafluoro-4'-pentoxy-benzyloxy units is reported. The new compounds have been characterized by using elemental analyses and UV-Vis, FT-IR, and mass spectroscopic data. The electrochemical properties of the manganese phthalocyanine complexes were investigated by cyclic and square wave voltammetry and the nature of the observed redox processes was studied by spectroelectrochemistry.
The results of studies on the synthesis of photosensitizers conducted the last 10 years in frame of health care programs funded by the Moscow Government are reported.
