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A number of substituted manganese phthalocyanines (PcMn), which are easily soluble in organic solvents, have been synthesized with good yields (up to 76%) and high purity. PcMn with manganese + 2 oxidation state without axial ligands was obtained for the first time and thoroughly characterized. It was shown that PcMn forms, PcMnIIIX, PcMnII or [LPc...
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... last decades have not only retained the usual areas of application and research of phthalocyanines (Pc) but have opened new ones for this most interesting class of organic dyes. The steady interest in manganese phthalocyanine (PcMn) was defined in the 1960s, when it was found that it is no less active than PcFe as a catalyst of oxidation processes and a role of manganese in a photosynthesis was also discovered. Moreover, the PcMn porphyrin-like structure makes its study espe- cially attractive as a model of one of the photosynthetic system components. However, all the investigations of PcMn performed up until now concerned the complex in a solid state or its solutions in coordinating solvents, conditions where the intermolecular interactions deformed the true picture of its behaviour. The main reason for such a situation in PcMn chemistry was its extremely low solubility. The synthesis of a soluble tert -butyl substituted complex was mentioned only once, but its properties were not studied [1]. The investigation into the state and properties of unsubstituted PcMn in solutions followed in a complex way from the brief publication of Elvidge and Lever [2] to the fundamental work of the same group carried out 20 years later [3]. Omitting the details of the most important investigations [4–11], we want to note only one result, confirmed by the X-ray data: the μ -oxo dimer of PcMn III complex — [PyxPc- Mn III ] 2 O — was established as a final product of PcMn II oxidation by dioxygen in coordinating solvents [6]. The main purpose of this paper is to clarify the fundamental aspects of PcMn coordination chemistry based on the wide series of soluble substituted PcMn derivatives. Substituted PcMn ( I–XIII ) were prepared by heating manganese acetate with the corresponding phthalo- dinitrile in a sealed tube. The time and temperature of the reactions varied for different compounds in the range 15–90 min and 180–280°C, respectively [12, 13]. The obtained compounds were complexes of Mn II ( Ic–XIIIc ) (Fig. 1) but during the purification in aerobic conditions most of them were oxidized into complexes of Mn III : PcMn III X ( Ia–XIIIa ) or (L ϫ PcMn III ) 2 O (in the presence of coordinating ligands L). The octanitro and octa(phenylsulphonyl) substituted complexes were isolated as PcMn II ( XIIc, XIIIc ), the corresponding PcMn III X ( XIIa, XIIIa , X = OAc) were obtained only when XIIc and XIIIc were treated with acetic acid in air. The yields of analytically pure products were 30–76%. Electronic absorption spectra of substituted PcMn in solution ( c ഠ 10 –5 M) were registered in the region 300–900 nm using a ‘Specord’ spectrophotometer. Magnetic moments were recorded by a Faraday method. Electron spin resonance (ESR) spectra were recorded on a ‘Radiopan’ SE/X-2542 radio- spectrometer with a working frequency of 9.45 GHz in molybdenum tubes with d = 0.3 cm, c PcMn ഠ 10 –2 – 10 –3 M, T = 77 K. The illumination of the solutions in the course of the photochemical investigations was performed by visible light or by mercury lamp. Voltammetry was carried out in three-electrode cells in helium atmosphere. A standard calomel electrode was used as a reference and gold wire was used as a working electrode. Coulometric potentials were generated using a P-5827 potentiostat in the range –2.00 to –1.96 V. Pyridine and 1,2-dichlor- obenzene were twice distilled and dried over Al 2 O 3 . The compound Ic from the series of tert -butyl substituted complexes ( Ia–c ), which were chosen as basic subjects for our investigation is very active species, e.g. it reacts with dioxygen and water, and binds axial ligands. This is why we worked under anaerobic conditions and tried to avoid the presence of any impurities in the solution of Ic . The level of visible light was also always taken into account. The experiments in anaerobic conditions were carried out in vacuum apparatus at 10 –5 Torr with prior degassing by 20-fold repetition of freeze–pump– thaw cycles. Complex Ic was twice sublimed in vacuum at 693–703 K; the second sublimation was carried out just before experimentation. The content of dioxygen in the evacuated system was 10 –7 –10 –8 mol l –1 . It was measured using the equation 1/ T = K T ϫ [O 2 ] where T is the lifetime of rhoda- mine 6G in the triplet state under illumination by Ar laser in ethanol and K T = 10 9 –10 10 l mol –1 s –1 . Benzene and toluene were consequently washed with KMnO 4 solution in 10% H 2 SO 4 , 10% NaOH, H 2 O, then treated by Al 2 O 3 for chromatography (40/250) and twice distilled. Cyclohexene was prepared by the addition of 20 ml H 2 SO 4 into 180 ml cyclohexanol, distilled (349–351 K) under argon, shaken with NaCl and distilled under argon (356–357 K) once more. In order to avoid the desorption of impurities from vacuum grease, the latter was changed before each experiment. The cyclohexane content was controlled using gas chromatography on (i) Carbowax 1500 on Chromaton, l = 2 m, gas carrier: He, W g = 30–60 ml min –1 , temperature of column: 318 K, temperature of evaporator: 383 K; (ii) 5% XE-60 on Chromaton, l = 3 m, gas carrier: N 2 , W g = 30–60 ml min –1 , temperature of column: 328 K, temperature of evaporator: 423 K. In order to identify PcMn co-ordination and valence forms in solution we have synthesized a number of macrocycle complexes substituted in benzene rings (Fig. 1), possessing high solubility in inert organic solvents such as benzene or toluene. All details of the synthesis and some properties of these complexes are described in our previous publications [12, 13]. Because complex I with tert -butyl groups in the benzene rings combines very high solubility with little electronic effect of the substituents, it was chosen as a basic compound for our investigation. The influence of various electron-donating and electron-withdrawing substituents on the chemical properties and stability of different PcMn forms was studied for other substituted compounds ( II–XIII ). PcMn III X (form a ) was shown to be the most stable form of PcMn I–XI in non-coordinating solvents under ambient conditions. The structure of these complexes was confirmed by elemental analysis, magnetic susceptibility and electronic spectral data as well as by the absence of signal in an ESR spectrum. The Q-band position in the electronic spectra of Ia–XIIIa essentially depends on the kind of substituents: there is significant bathochromic shift in the case of the electron-donating substituents and a less significant hypsochromic shift in the case of electron-withdrawing substituents (Fig. 2, Table 1). From the electronic spectra (Fig. 3) we can see that monomeric Mn III complexes Ia–Va and VIIa– XIIIa after the addition of coordinating organic bases such as pyridine, 4-aminopyridine and imida- zole to their solutions in the presence of water are converted into the corresponding μ -oxo species ( Ib– Vb, VIIb–XIIIb ). These μ -oxo complexes exhibit strong absorption at ~ 620 nm (Q band) and at ~ 330 nm (B ...
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... was also discovered. Moreover, the PcMn porphyrin-like structure makes its study espe- cially attractive as a model of one of the photosynthetic system components. However, all the investigations of PcMn performed up until now concerned the complex in a solid state or its solutions in coordinating solvents, conditions where the intermolecular interactions deformed the true picture of its behaviour. The main reason for such a situation in PcMn chemistry was its extremely low solubility. The synthesis of a soluble tert -butyl substituted complex was mentioned only once, but its properties were not studied [1]. The investigation into the state and properties of unsubstituted PcMn in solutions followed in a complex way from the brief publication of Elvidge and Lever [2] to the fundamental work of the same group carried out 20 years later [3]. Omitting the details of the most important investigations [4–11], we want to note only one result, confirmed by the X-ray data: the μ -oxo dimer of PcMn III complex — [PyxPc- Mn III ] 2 O — was established as a final product of PcMn II oxidation by dioxygen in coordinating solvents [6]. The main purpose of this paper is to clarify the fundamental aspects of PcMn coordination chemistry based on the wide series of soluble substituted PcMn derivatives. Substituted PcMn ( I–XIII ) were prepared by heating manganese acetate with the corresponding phthalo- dinitrile in a sealed tube. The time and temperature of the reactions varied for different compounds in the range 15–90 min and 180–280°C, respectively [12, 13]. The obtained compounds were complexes of Mn II ( Ic–XIIIc ) (Fig. 1) but during the purification in aerobic conditions most of them were oxidized into complexes of Mn III : PcMn III X ( Ia–XIIIa ) or (L ϫ PcMn III ) 2 O (in the presence of coordinating ligands L). The octanitro and octa(phenylsulphonyl) substituted complexes were isolated as PcMn II ( XIIc, XIIIc ), the corresponding PcMn III X ( XIIa, XIIIa , X = OAc) were obtained only when XIIc and XIIIc were treated with acetic acid in air. The yields of analytically pure products were 30–76%. Electronic absorption spectra of substituted PcMn in solution ( c ഠ 10 –5 M) were registered in the region 300–900 nm using a ‘Specord’ spectrophotometer. Magnetic moments were recorded by a Faraday method. Electron spin resonance (ESR) spectra were recorded on a ‘Radiopan’ SE/X-2542 radio- spectrometer with a working frequency of 9.45 GHz in molybdenum tubes with d = 0.3 cm, c PcMn ഠ 10 –2 – 10 –3 M, T = 77 K. The illumination of the solutions in the course of the photochemical investigations was performed by visible light or by mercury lamp. Voltammetry was carried out in three-electrode cells in helium atmosphere. A standard calomel electrode was used as a reference and gold wire was used as a working electrode. Coulometric potentials were generated using a P-5827 potentiostat in the range –2.00 to –1.96 V. Pyridine and 1,2-dichlor- obenzene were twice distilled and dried over Al 2 O 3 . The compound Ic from the series of tert -butyl substituted complexes ( Ia–c ), which were chosen as basic subjects for our investigation is very active species, e.g. it reacts with dioxygen and water, and binds axial ligands. This is why we worked under anaerobic conditions and tried to avoid the presence of any impurities in the solution of Ic . The level of visible light was also always taken into account. The experiments in anaerobic conditions were carried out in vacuum apparatus at 10 –5 Torr with prior degassing by 20-fold repetition of freeze–pump– thaw cycles. Complex Ic was twice sublimed in vacuum at 693–703 K; the second sublimation was carried out just before experimentation. The content of dioxygen in the evacuated system was 10 –7 –10 –8 mol l –1 . It was measured using the equation 1/ T = K T ϫ [O 2 ] where T is the lifetime of rhoda- mine 6G in the triplet state under illumination by Ar laser in ethanol and K T = 10 9 –10 10 l mol –1 s –1 . Benzene and toluene were consequently washed with KMnO 4 solution in 10% H 2 SO 4 , 10% NaOH, H 2 O, then treated by Al 2 O 3 for chromatography (40/250) and twice distilled. Cyclohexene was prepared by the addition of 20 ml H 2 SO 4 into 180 ml cyclohexanol, distilled (349–351 K) under argon, shaken with NaCl and distilled under argon (356–357 K) once more. In order to avoid the desorption of impurities from vacuum grease, the latter was changed before each experiment. The cyclohexane content was controlled using gas chromatography on (i) Carbowax 1500 on Chromaton, l = 2 m, gas carrier: He, W g = 30–60 ml min –1 , temperature of column: 318 K, temperature of evaporator: 383 K; (ii) 5% XE-60 on Chromaton, l = 3 m, gas carrier: N 2 , W g = 30–60 ml min –1 , temperature of column: 328 K, temperature of evaporator: 423 K. In order to identify PcMn co-ordination and valence forms in solution we have synthesized a number of macrocycle complexes substituted in benzene rings (Fig. 1), possessing high solubility in inert organic solvents such as benzene or toluene. All details of the synthesis and some properties of these complexes are described in our previous publications [12, 13]. Because complex I with tert -butyl groups in the benzene rings combines very high solubility with little electronic effect of the substituents, it was chosen as a basic compound for our investigation. The influence of various electron-donating and electron-withdrawing substituents on the chemical properties and stability of different PcMn forms was studied for other substituted compounds ( II–XIII ). PcMn III X (form a ) was shown to be the most stable form of PcMn I–XI in non-coordinating solvents under ambient conditions. The structure of these complexes was confirmed by elemental analysis, magnetic susceptibility and electronic spectral data as well as by the absence of signal in an ESR spectrum. The Q-band position in the electronic spectra of Ia–XIIIa essentially depends on the kind of substituents: there is significant bathochromic shift in the case of the electron-donating substituents and a less significant hypsochromic shift in the case of electron-withdrawing substituents (Fig. 2, Table 1). From the electronic spectra (Fig. 3) we can see that monomeric Mn III complexes Ia–Va and VIIa– XIIIa after the addition of coordinating organic bases such as pyridine, 4-aminopyridine and imida- zole to their solutions in the presence of water are converted into the corresponding μ -oxo species ( Ib– Vb, VIIb–XIIIb ). These μ -oxo complexes exhibit strong absorption at ~ 620 nm (Q band) and at ~ 330 nm (B band) (Fig. 4, curve 2). The ability of PcMn III X to form the dimers depends significantly on the nature of the sub- stituents and their position in the Pc ring. The introduction of strong electron-withdrawing groups facilitates the formation of dimers (in the case of IIb, XIIb and XIIIb ) which is essentially complete in the presence of weakly coordinating acetone. On the other hand, complexes with neutral or electron- donating substituents ( Ia, IIIa–Va, VIIIa, IXa and XIa ) form the corresponding dimers only after the addition of pyridine. The dimer stability is also influenced by the kind of substituents — μ -oxo species with strong electron-withdrawing groups are reconverted into PcMn III X only in the presence of strong proton donors, such as hydrochloric acid, while the dimers with neutral or electron-donating groups form corresponding monomers even in the presence of water or ethanol. The compound VIa does not form the corresponding μ -oxo dimer under the described conditions because of steric hindrance of the non-coplanar ortho -substituted phenyl groups. Therefore, such complexes are of interest as catalysts for the different processes in weakly alkaline solutions where dimerization of other PcMn takes place with the loss of their catalytic activity. Thus, the results obtained allow the management of the ability of PcMn to form the μ -oxo dimers. When Ia , dissolved in benzene, reacts with triethyla- mine or potassium hydroxide water–acetone mixture in anaerobic conditions a compound is formed, whose electronic spectrum is typical for the ordinary phthalocyanines with the Q band being significantly blue-shifted relatively to the spectrum of Ia while the band at about 500 nm is absent (Fig. 4, curve 3, Table 1). After evaporation of the solvent and sublimation of the dry residue in vacuum, PcMn II ( Ic ) was obtained. The structure of this complex was confirmed by elemental analysis and magnetic susceptibility data as well as by an ESR spectrum in toluene at 77 K, which was typical for low-spin Mn (II) compounds (Fig. 5). The stability of substituted PcMn II against oxidation depends significantly on the kind of substituents. For example, the species Ic–XIc converted readily (without any intermediates) into Ia–XIa (X = OH) in benzene solutions in aerobic conditions, while the complexes XIIc and XIIIc , containing eight strong electron-withdrawing groups, are very stable under these conditions. These compounds are sufficiently stable to enable their purification by the column chromatography method. The complexes XII and XIII are the first examples of substituted PcMn stable in solutions in air, both in the + 2 and + 3 oxidation states of the manganese atom. It seems perspective to use such complexes as catalysts of various oxidation processes. Unexpectedly, it was found that the electronic spectrum of the Ic benzene solution transforms into the spectrum of Ia by addition of acetic acid in anaerobic conditions ([Pc]/[O ] ~ 100). It is possible to suggest that in the absence of other oxidants the following reaction takes ...
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... PcMn (I-XIII) were prepared by heating manganese acetate with the corresponding phthalo- dinitrile in a sealed tube. The time and temperature of the reactions varied for different compounds in the range 15-90 min and 180-280°C, respectively [12,13]. The obtained compounds were complexes of Mn II (Ic-XIIIc) ( Fig. 1) but during the purification in aerobic conditions most of them were oxidized into complexes of Mn III : PcMn III X (Ia-XIIIa) or (L PcMn III ) 2 O (in the presence of coordinating ligands L). The octanitro and octa(phenylsulphonyl) substituted complexes were isolated as PcMn II (XIIc, XIIIc), the corresponding PcMn III X (XIIa, XIIIa, ...
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... order to identify PcMn co-ordination and valence forms in solution we have synthesized a number of macrocycle complexes substituted in benzene rings Fig. 1), possessing high solubility in inert organic solvents such as benzene or toluene. All details of the synthesis and some properties of these com- plexes are described in our previous publications ...
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... Q-band position in the electronic spectra of Ia-XIIIa essentially depends on the kind of sub- stituents: there is significant bathochromic shift in the case of the electron-donating substituents and a less significant hypsochromic shift in the case of electron-withdrawing substituents ( Fig. 2, Table ...
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... nPy (λ max = 560 and 880 nm) and anion radical Pc -• Mn III (λ max = 480 and 840 nm). This suggestion is based on well-known electronic spectra of other PcM cation and anion radicals [14][15][16][17] as well as on the spectrum of electrochemically obtained tert-butyl substituted Pc + • Mn III Cl (E 1/2 = 0.97 V, λ max = 575 and 860 nm, see below) (Fig. 14). Our hypothesis was confirmed also by the following dependence of the spectral picture on the nature of the substituents: in the case of electron-withdrawing substituents the bands of the anion-radical isomer were more intense; on the contrary, in the case of electron-donating sub- stituents the bands of the cation radical were more ...
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... photoreduction of complex Ia into Ic pro- ceeds without any intermediates and after illumination the ESR spectrum shows the presence (Fig. 10). Besides, it was shown that the back oxidation can also proceed by two pathways depending on pyridine content in solution: (i) if the pyridine concentration was suffi- cient to form [PyPcMn III ] 2 O ([Py]/ [Pc] 100) the formation of 'Y' was observed; (ii) if [Py]/ [Pc] 10 an ESR spectrum of initial PcMn II 2Py disappears without ...
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... reaction. The latter result allows the Changing the conditions of the reversible photo- reduction in pyridine we achieved acceleration of the PcMn II dark oxidation reaction. For example, in the system 4-(t-Bu) 4 -PcMnOH -Py -EtOH -H 2 O in vacuum several cycles of consequent reduction (in the light) -oxidation (in the dark) of PcMn were realized (Fig. ...
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... obtained potentiodynamic curves and absorp- tion spectra of reduced forms for complex VIII are shown in Fig. 12. We can see that the initial 3-(phenylthio)-PcMn III Cl (VIIIa) (λ max in pyri- dine = 775 nm), accepting one electron (E 1/2 = -0.09 V), converts into 3-(phenylthio)-PcMn (II) (VIIIc), which exhibits a multiband absorption spectrum in pyridine (λ max = 684 nm) and an ESR spectrum analogous to Py 2 PcMn II (Ic). In the course of the ...
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... to the PcMn II spec- trum. So, the second electron is also localized at the metal atom with 3-(PhS) 4 -PcMn (I) formation; the latter complex, in accordance with presumption, is ESR-silent. Only the third electron (E 1/2 = -1.49 V) is localized on the macrocycle resulting in PcMn I anion-radical formation; its ESR spectrum is shown in Fig. 13. Simultaneously in the absorption spec- trum, the intensity of the bands at about 500 and 800 nm, ascribed in literature [14][15][16] to PcM anions, is significantly ...
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... on the results obtained (Fig. 12), the reduction of PcMn III X in pyridine can be repre- sented by the following ...
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... electrochemical oxidation of substituted PcMn III X in 1,2-dichlorobenzene exhibits two oxida- tion waves. The first one (E 1/2 = 0.97 V for complex Ia) is reversible and corresponds to the cation- radical Pc + • Mn III X formation. The absorption spectrum of this species (λ max = 574 and 840 nm, Fig. 14) is analogous to spectra of other PcM cation radicals [16,17]. It is worth noting that complex V with strong electron-donating substituents in the macrocycle is able to form a stable-in-air cation radical when hot pyridine is added to the Va solution (Fig. 14). Both cation-radical species, obtained chemically and electrochemically, are ...
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... + • Mn III X formation. The absorption spectrum of this species (λ max = 574 and 840 nm, Fig. 14) is analogous to spectra of other PcM cation radicals [16,17]. It is worth noting that complex V with strong electron-donating substituents in the macrocycle is able to form a stable-in-air cation radical when hot pyridine is added to the Va solution (Fig. 14). Both cation-radical species, obtained chemically and electrochemically, are ...
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... the oxidation of complex Ia in 1,2-dichlor- obenzene can be represented by the following scheme: In the course of our investigation a good correla- tion between the redox potentials and the substituent σ n -constants was observed (Fig. 15): the complexes with strong electron-withdrawing sub- stituents in the macrocycle are easier to reduce and harder to oxidize; an inverse picture was observed for complexes with electron-donating substituents. The compounds with strong electron-donating sub- stituents (Va and XIa) form cation radicals that are even stable in ...
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Acid-base reactions of (octakis(3-trifluoromethylphenyl)phtalocyaninato) manganese(III) acetate (AcO)MnPc(3-CF3Ph)8, (octakis(3-trifluoromethylphenoxy)phtalocyaninato) manganese(III) acetate (AcO)MnPc(3-CF3PhO)8 and (octakis(3,5-di-tert-butylphenoxy) phtalocyaninato) manganese(III) acetate (AcO)MnPc(3,5-di-
t
BuPhO)8 are studied spectrophotometrica...
A number of substituted manganese phthalocyanines (PcMn), which are easily soluble in organic solvents, have been synthesized with good yields (up to 76%) and high purity. PcMn with manganese +2 oxidation state without axial ligands was obtained for the first time and thoroughly characterized. It was shown that PcMn forms, PcMnIIIX, PcMnII or [LPcM...
Citations
... MnPc and its substituted derivatives [25] can contain either Mn(II) and Mn(III); the very complex redox equilibria between the two oxidation states are highly sensitive to the presence of even traces of water. Additionally, reactions of Mn(II) derivatives with dioxygen (O2) are very sensitive to the experimental conditions. ...
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.
... The chemical structure of 1/2 was confirmed by analysis of these elemental composition and spectral data (see Experimental) which are consistent with the data reported by authors [48]. The UV-vis spectra were characteristic of (phthalocyaninato) manganese(III) derivatives [49,50]. The spectra of 1/2 in solutions contain two intensive absorbance assigned as B-and Q-bands at λ 397, 738/395, 723 nm. ...
Known affinity of coordination unsaturated manganese(III) phthalocyanines to N-containing bases have been exploited to synthesize photoactive dyads based on manganese(III) 3-trifluorometylphenyl-/3-trifluorometylphenoxy-coated phthalocyanine and pyridine/1′-N-methyl-2′-(pyridin-4-yl)pyrrolidino[3',4':1,2][60]fullerene. The structure and spectral properties of these electron donor-acceptor dyads have been described by chemical thermodynamics/kinetics, UV–vis, IR, ¹H NMR spectroscopy, fluorescence, and DFT calculation methods. Comparison of their spectroscopic parameters with those of the corresponding both individual constituents and covalently bonded phthalocyanine–fullerene dyad reveals that there is intramolecular photoinduced electron transfer and related to this prospects in solar energy conversion devices in the case of coordination dyads studied.
... The chemical structure of (AcO)MnTAP(4-t BuPh) 8 (1) and (AcO) MnPc(3,5-di-t BuPhO) 8 (2) synthesized was confirmed by these elemental composition and spectral data (see Experimental) which are identical with the data reported by authors [16]. The UV-Vis spectra were characteristic of (tetraazaporphinato)/(phthalocyaninato) manganese(III) derivatives [26][27][28]. The spectra of 1 and 2 in solutions contain two intensive absorbance assigned as B-and Q-band at λ 421, 673 and 407, 727 nm respectively. ...
The self-assembly of (octakis(4-tret-butyl-phenyl)tetraazaporphyrinato) manganese(III) acetate, (AcO)MnTAP(4-tBuPh)8or (octakis(3,5-di-tert-butylphenoxy)phthalocyaninato) manganese(III) acetate, (AcO)MnPc(3,5-di-tBuPhO)8with 1′-N-methyl-2′-(pyridin-4-yl)pyrrolidino[3′,4':1,2][60]fullerene, PyC60resulted in the forma-tion of 1: 1 supramolecular system (dyad) in toluene was studied by the methods of chemical kinetics/ther-modynamics and spectroscopy (UV-visible,fluorescence, IR and1H NMR). It is found that the dyad formationmechanism depends on a macrocycle type. Theoretical calculations using B3LYP-D3/6-31G (d,p) basis set re-vealed stable complexation between (AcO)MnTAP(4-tBuPh)8/(AcO)MnPc(3,5-di-tBuPhO)8and full-eropyrrolidine moiety. The dyad LUMO energy levels are predominantly spread on the C60unit and the HOMOenergy levels are mainly spread on the tetraazaporphyrin/phthalocyanine ring. The photoinduced electrontransfer testing by the substantial quenching of thefluorescence emission of the manganese(III) complexes byaxially bonded [60]fulleropyrrolidin gives the positive result that shows prospects of the studying dyads as theactive layers in solar energy conversion devices. The photocurrent density of the manganese(III) tetra-azaporphyrin/phthalocyaninefilms modifying the titanium electrode surface increases by factors of 2 whenaxially bonded [60]fulleropyrrolidine is present in the supramolecule structure (2)
... We have suggested earlier the full scheme of the transformations of the liposoluble PcMn derivatives in solutions [19,20] (Scheme 1). As a part of our continued interest in PcMn coordination chemistry, we have synthesized a number of water-soluble PcMns in order to elucidate the features of their coordination transformations in water. ...
... Phthalocyanine complexes of Mn(II) (form c) are typically unstable in aerated solutions. Previously we have reported three compounds that proved to be resistant to air in form c; those are complexes having eight strong electronwithdrawing substituents: octanitro-, octa(phenylsulfonyl)and octachlorooctakis(decylsulfanyl)substituted PcMn(II) [19,20]. ...
... Our earlier studies had shown that complexes of Mn(III) demonstrate stronger dependence of their Q-band positions on the substituent nature when compared to PcMn(II) [19,20]. Unlike the liposoluble PcMns, in the spectra of water-soluble compounds 2c-4c Q-bands are shifted more towards the red compared to the Q-bands of the unsubstituted analogs than Q-bands of 2a-4a ( Table 2). ...
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 octacarboxyphthalocyanine tetraanhydride. Compounds were characterized by elemental analysis and mass, IR and UV-vis spectroscopy. In general, coordination chemistry of the compounds studied is similar to this one of liposoluble PcMns but some new findings have been obtained. Three coordination forms — PcMn(II), PcMn(III)X(X = Cl-, OAc-, …) and [LPcMn(III)]2O(L = Py, Et3N, …) have been obtained for all the new compounds. The equilibrium between three electronic isomers — Pc+•Mn(I) × L, PcMn(II) × nL, (n = 1, 2) and Pc-•Mn(III) × 2L has been observed in PcMn aqueous solutions upon the addition of organic bases L (Py, Et3N, …).
... Metal phthalocyanines (PcM) are a very important class of compounds because of their diverse properties and applications. Interest in manganese phthalocyanine (PcMn) has emerged more than half a century ago and continues till now [1][2][3][4][5][6][7][8][9][10][11][12][13]. Major interest in PcMn along with PcFe lies in the high catalytic activity of this compound. ...
... Among the last publications on PcMn [14][15][16][17][18][19][20][21][22][23][24][25][26] only a few studies deal with coordination properties, although the variety of PcMn coordination and valence forms makes the investigation of its coordination chemistry of considerable importance. We have previously suggested the full scheme of photo and dark transformations of PcMn derivatives in solutions (Scheme 1, [13]). Herein we wish to present the investigation of this scheme validity for the series of new substituted manganese phthalocyanines with diversified electronic and steric peculiarities. ...
... Complex 10 (Table 1) treatment in air does not lead to complete Mn(II) oxidation but instead results in isolation of stable in air form c during 10 purification done by column chromatography with benzene. Our earlier studies [13,28] had shown that form a is the most stable in non-coordinating solvents under ambient conditions for PcMn bearing neutral and electron-donating groups. It seems that in the case of complex 10 electronwithdrawing substituents stabilize PcMn(II). ...
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 [LPcMn(III)]2O were fixed for all complexes. The equilibrium of three electronic isomers — Pc+· Mn(I) × L, PcMn(II) × Ln and Pc-· Mn(III) × 2L — has been observed in solutions of all PcMn(II) in the presence of organic base L.
... 72 In interaction with the solvent the central metal can oxidize from Mn(II) to Mn(III). 73,74 The different coordinations of the solvent molecules on phthalocyanine causes changes in the spectra. 73 We could not produce stable solutions in acids and measure their spectra. ...
We investigated quantitatively the solubility properties of a number of unsubstituted metal phthalocyanines with various metal atoms such as Co, Cu, Fe, Mg, Mn, Ni, Sn, and Zn. We studied three categories of solvents: conventional solvents, ionic liquids, and acids. The conventional liquids comprised 20 typical representatives from acetone to toluene. We tested two ionic liquids and five acids. For each solution we measured the molar absorption coefficient and the saturation concentration (or estimated these values if the solubility was too low). The absorption coefficients and saturation concentrations were derived from UV–vis absorption measurements of the Q-band. The solution spectra are presented and discussed as well as the chemical properties (stability) of the solutions.
In this paper, new metallophthalocyanines (MPc) were synthesized by cyclotetramerization of 4-{[4-(2-morpholin-4-ylethoxy)benzyl]oxy/phlhalonitrile.T oi ncreasep otentiala pplicationo fM Pcs, r edoxa ctiveC o(II), M n(III)a ndT i(IV)Om etal centers were preferred. MPcs were decorated with redox active and electropolymerizable {[4-(2-morpholin-4-ylethoxy)benzyl]oxy} substituents in order to coat the complexes with electropolymerization. Synthesized MPcs were characterized with UV-Vis, IR, ¹H-NMR, I3C-NMR and MS (ES⁺ and MALDI-TOF) spectroscopies and voltammetry and in situ spectroelectrochemistry techniques. Voltammetric and in situ spectroelectrochemical analyses indicated that all complexes gave metal based reduction processes in addition to the Pc based processes. During oxidation reaction, all complexes were coated on the glassy carbon electrode (GCE) surface with oxidative electropolymerization reactions. Redox active and conductive GCE/MPc electrodes were constructed with the electropolymerization of MPcs and these electrodes were tested as active pesticide sensors for eserine, parathion, diazinon and fenitrothion pesticides. CoPc did not interact with any pesticide compound while MnPc and TiOPc selectively sensed diazinon and eserine, respectively.
The reaction of (octaphenyltetraazaporphyrinato)magnesium(II) with manganese(II) chloride in dimethylformamide gave (chloro)(octaphenyltetraazaporphyrinato)manganese(III). Reactions of the latter with nitrogen-containing bases were studied. The kinetic parameters of the transmetalation of (octaphenyltetraazaporphyrinato) magnesium(II) with MnCl2 in dimethylformamide at 323, 333, and 343 K were determined, and a probable reaction mechanism was proposed.
Nickel(II), manganese(III), and magnesium(II) porphyrazines are synthesized and investigated as active electrode components of polyvinyl chloride plasticized membranes for ion-selective electrodes (ISE). The potentiometric response of membranes based on metalloporphyrazines doped with 1,3-dihexadecylimidazolium chloride (ionic additive) relative to benzylpenicillin and iodide anions is studied. It is found that the introduction of the ionic additive significantly improves the electrochemical characteristics of the ISE: the slope of the electrode function in benzylpenicillinate solutions is (58 ± 7) mV/dec and c
min = 7 × 10−5 M, and in iodide solutions, (55 ± 2) mV/dec and c
min = 6 × 10−6 M. It is shown that the ISE based on manganese(III) porphyrazine with an ionic additive can be used to determine iodide in Iodinol preparation.
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