Metal (Co, Fe) tribenzotetraazachlorin-fullerene conjugates: impact of direct p-bonding on the redox behaviour and oxygen reduction reaction (original) (raw)
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Electrochemistry Communications, 2009
Novel hexabutylsulphonyltribenzotetraazachlorin-fullerene (C 60) complexes of iron (FeHBSTBTAC-C 60) 25 and cobalt (CoHBSTBTAC-C 60) have been synthesized and their electrochemistry and oxygen reduction 26 reaction (ORR) compared with their octabutylsulphonylphthalocyanine analogues (FeOBSPc and CoO-27 BSPc). It is proved that electron-withdrawing substituents (-SO 2 Bu and C 60) on phthalocyanine macrocy-28 cle exhibit distinct impact on the solution electrochemistry of these metallophthalocyanine (MPc) 29 complexes. The more electron-withdrawing C 60 substituent suppressed ORR compared to the-SO 2 Bu 30 in alkaline medium. FeOBSPc showed the best ORR activity involving a direct 4-electron mechanism, a 31 rate constant of $1 Â 10 8 cm 3 mol À1 s À1 and a Tafel slope of À171 mV dec À1. 32
Russian Chemical Bulletin, 2011
The ionic complexes simultaneously containing negatively charged coordination structures of metal phthalocyanines and fullerene anions, viz., {Mn II Pc(CH 3 CH 2 S-) x •(I-) 1-x }•(C 60 •-)• •(PMDAE +) 2 •C 6 H 4 Cl 2 (PMDAE is N,N,N´,N´,N´ pentamethyldiaminoethane, x = 0.87, 1) and {Zn II Pc(CH 3 CH 2 S-) у •(I-) 1-y } 2 •(C 60-) 2 •(PMDAE +) 4 •(C 6 H 4 Cl 2) (y = 0.5, 2) were syn thesized. The both compounds were obtained as single crystals, which made it possible to study their crystal structures. In complex 1, the fullerene radical anions form honeycomb like layers in which each fullerene has three neighbors with center to center interfullerene distances of 10.13-10.29 Å. Rather long distances between the C 60 •-radical anions results in the retention of monomeric C 60 •-in this complex down to the temperature of 110(2) K. In complex 2, fullerenes form dimers (C 60-) 2 bonded by one CC bond. The dimers are packed in corrugated honeycomb like layers with interfullerene center to center distances of 9.90-10.11 Å. Manganese(II) and zinc(II) phthalocyanines coordinate iodide and ethanethiolate anions to the central metal atom to form unusual negatively charged coordination structures M II Pc(An-) (Anis anion) packed in dimers {M II Pc(An-)} 2 with a short distance between the phthalo cyanine planes (3.14 Å in 1 and 3.27 Å in 2). The pthalocyanine dimers also form layers with the PMDAE + cations, and these layers alternate with the fullerene layers. The packing of spherical fullerenes with planar phthalocyanine molecules is attained by the insertion of fullerenes between the phenylene groups of phthalocyanines. The π-π interactions of the porphyrin macrocycle with five or six membered fullerene rings are characteristic of the earlier studied ionic porphy rin and fullerene complexes. Such interactions are not observed for ionic complexes 1 and 2. Key words: fullerene С 60 , manganese(II) and zinc(II) phthalocyanines, crystal structure, dimerization of C 60 •-, coordination of anions with metal phthalocyanines.
Polyhedron, 2011
The syntheses of new ball-type Co(II) phthalocyanines containing 4,4 0-(9H-fluorene-9,9-diyl)diphenol substituents at non-peripheral (complex 6) and peripheral (complex 7) positions are presented. These complexes were characterized by UV-Vis, FT-IR, mass spectroscopy and electrochemical methods. Both complexes exhibit metal and ring based redox processes, typical of cobalt phthalocyanine complexes. For 6, the metal based reduction was observed at À0.46 V followed by a ring based reduction at À1.40 V. The metal oxidation for 6 was observed at +0.16 V and the ring based oxidation at +1.05 V. For 7, reductions are easier but the oxidations are more difficult. The metal based reduction for 7 was observed at À0.38 V followed by a ring based reduction at À1.03 V. The metal oxidation for 7 was observed at +0.20 V and the ring based oxidation at +1.35 V.
Journal of Porphyrins and Phthalocyanines, 2014
The complex of fullerene C 60 with dipyridinated iron(II) phthalocyanine [Fe(II)Pc(C 5 H 5 N) 2 ] . C 60 . 4C 6 H 4 Cl 2 (1) has been obtained as single crystals. According to the IR and UVvisibleNIR spectra, 1 is molecular solid with no charge transfer from Fe(II)Pc(C 5 H 5 N) 2 to C 60 . C 60 molecules form closely packed linear columns in 1 along the b axis with a uniform interfullerene centerto center distance of 9.99 Å and multiple short van der Waals (vdW) C…C contacts between fullerenes of 3.10-3.18 Å. Totally each Fe(II) Pc(C 5 H 5 N) 2 unit is surrounded by four C 60 molecules two of which form short vdW C…C contacts with the phthalocyanine plane locating near two adjacent phenylene substituents of Fe(II)Pc. The Fe(II)Pc(C 5 H 5 N) 2 geometry remains almost unchanged as compared with that of fullerene free Fe(II)Pc(C 5 H 5 N) 2 . The iron(II) atoms are located exactly in the Pc plane, the FeN(C 5 H 5 N) bond length is 2.038(3) Å and the averaged of the FeN(Pc) bond length is 1.935(3) Å. Bisaxially coordinated iron(II) phthalocyanine complex with acetonitrile Fe(II)Pc(CH 3 CN) 2 does not cocrystallize with C 60 . Nevertheless, good quality crystals of [Fe(II)Pc(CH 3 CN) 2 ] . 2C 6 H 4 Cl 2 (2) were isolated in this synthesis. That is the first structure of bisaxially coordinated metal phthalocyanine complex with nitrile containing solvent. Acetonitrile unusually strongly coordinates to Fe(II)Pc with the Fe-N(CH 3 CN) bond length of 1.938(1) Å. The iron(II) atoms are located in the Pc plane and the averaged length of the FeN(Pc) bonds is 1.934(1) Å.
Ionic Interactions between Charged Phthalocyanine and Fullerene Derivatives
Macroheterocycles, 2014
The syntheses of positively and negatively charged zinc(II) phthalocyanine and fullerene derivatives are described. UVvis absorption and fluorescence spectra show that ground and excited state interactions between oppositely charged phthalocyanine and fullerene derivatives occur. In contrast to the more complex synthesis of covalently connected dyads of phthalocyanines and fullerenes, the ionic interaction is more easily realized by simple mixing of oppositely charged components. This ionic interaction leads to a significant increase of the photocatalytic activity of phthalocyanines in the photooxidation of 2-mercaptoethanol by molecular oxygen.
Polyhedron, 2011
A novel type of ionophore ligands, 3 0-(2,3-dihydroxypropylthio)-phthalonitrile and 4 0 (2,3-dihydroxypropylthio)-phthalonitrile, and their aand b-tetrasubstituted metallo phthalocyanines, (MPc), (M = Zn II , Co II , Mn III Cl, Fe III Ac, Cu II) have been prepared and fully characterized by elemental analysis, FT-IR, 1 H and 13 C NMR, and MS (ESI and Maldi-TOF). The complexes are soluble in both polar and non-polar solvents, such as MeOH and EtOH, THF, CHCl 3 and CH 2 Cl 2. The spectroscopic properties of the complexes are affected strongly by the electron-donating sulfanyl units on the periphery of the phthalocyanines. The cation binding properties of the complexes, for example using Ag I and Pd II , were evaluated by UV-Vis spectroscopy and the results show the formation of polynuclear phthalocyanine complexes. Functional donors on the periphery of the zinc and copper complexes coordinate to Ag I and Pd II to give ca. a 2:1 metal-phthalocyanine complex binding ratio for the concentration of 2.5 Â 10 À5 M (Pc) and 1.0 Â 10 À3 M (Metal ions). Voltammetric and in-situ spectroelectrochemical studies were performed to characterize the redox behavior of the complexes. An in-situ electrocolorimetric method was applied to investigate the colors of the electro-generated anionic and cationic forms of the complexes.
Polyhedron, 2011
Mononuclear cobalt phthalocyanine (CoPc) substituted at the non-peripheral 8 and peripheral positions 9 with 1,1 0-binaphthyl-8,8 0-diol and ball-type dinuclear Co 2 Pc 2 substituted at the non-peripheral 10 and peripheral 11 positions with the same substituent are reported. The complexes with 1,1 0-binaphtholbridges were prepared from the corresponding phthalonitriles 4-7. The effects of the position of substituent on spectral, electrochemical and spectroelectrochemical properties of these complexes were also explored. The mononuclear complexes 8 and 9 exhibited one metal reduction, one ring reduction and one ring oxidation. The redox properties of the ball-type complexes 10 and 11 exhibited two reduction processes assigned to [(Co I Pc À2) 2 ] 2À /[(Co I Pc À3) 2 ] 4À (I), (Co II Pc À2) 2 /[(Co I Pc À2) 2 ] 2À (II) and one oxidation process assigned to [(Co III Pc À2) 2 ] 2+ /Co II Pc À2) 2 (III). The ball-type complexes are much easier to oxidize and more difficult to reduce than the corresponding monomers 8 and 9.
Metallophthalocyanines: Versatile Electron-Donating Building Blocks for Fullerene Dyads
The Journal of Physical Chemistry B, 2004
A thorough investigation on the physicochemical properties, including electrochemisty and photophysics, of a new class of donor-acceptor hybrids, namely, phthalocyanine-fullerene dyads, consisting of free base 1a and zinc and copper complexes 1b and 1c, respectively, brings new insights into the stabilization of chargeseparated radical ion pairs and the impact of redoxactive transition-metal centers on the photoperformance of macrocyclic phthalocyanines. In these dyads, the role of the phthalocyanines is twofold: First, it functions as an antenna (i.e., absorbing very efficiently light in the visible region of the solar spectrum) and, second, as a donor moleculesonce photoexcited. The initial photoexcitation is succeeded by an ultrafast electron transfer largely due to the strong electronic coupling between electron donor (Pc) and electron acceptor (C 60 ) generating surprisingly long-lived radical ion pairs Pc •+ -C 60 •with lifetimes of several nanoseconds. Large driving forces for the charge recombination and small reorganization energies of the Pc-C 60 ensembles corroborate slow charge recombination dynamics, which, in turn, helps to rationalize the long lifetimes of Pc •+ -C 60 •-.
Journal of Porphyrins and Phthalocyanines, 2003
A new family of pyrrole substituted metallophthalocyanine complexes, namely cobalt(II), iron(II), manganese(III), nickel(II) and zinc(II) tetrakis-4-(pyrrol-1-yl)phenoxy phthalocyanines (noted as M(TPhPyrPc), where M is the metallic cation) have been synthesized and fully characterized. In particular, the UV-visible spectra of the iron and nickel complexes showed extensive aggregation even at low concentrations. The cyclic voltammetry of the cobalt, iron and manganese complexes showed three to four redox couples assigned to metal and ring based processes. Spectroelectrochemistry of the manganese derivative confirmed that the synthesized complex is Mn III (TPhPyrPc -2 ) and that the reduction of Mn II (TPhPyrPc -2 ) to be centred on the ring and rather than on the metal, forming the Mn II (TPhPyrPc -4 ) species. Also, the electrochemical polymerization of these newly synthesized pyrrole-substituted phthalocyanines has been demonstrated in the case of the cobalt complex and the electrocatalytic activity of the obtained film has been tested towards the oxidation of L-cysteine.