Nickel phthalocyanine structure

The products are called 1,4-octasubstituted or 1,4,8,11,15,18,22,25-octasubstituted phthalocyanines. In this case only one structural isomer is possible. 3,6-Diheptylphthalonitrile when refluxed in pentan-1 -ol in the presence of nickel(II) acetate and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) for 48 hours yields the nickel phthalocyanine 16. 

In 1929, Linsted obtained samples of this complex from ICI chemists (Scottish Dyes Ltd was now owned by ICI). ICI had developed two routes leading to the phthalocyanine iron complex. One method started from phthalic anhydride, iron, and ammonia, while the second pathway proceeded from phthalimide, iron sulfide, and ammonia. In 1933/34, elucidation of the phthalocyanine structure was credited to Linstead. The corresponding copper and nickel phthalocyanines had been prepared in the meantime. ICI introduced the first Copper Phthalocyanine Blue to the market as early as 1935, and the Ludwigshafen subsidiary of the IG Farben-industrie followed suit with a corresponding product. 

An X-ray study of the structure of the phthalocyanines. Part I. The metal-free, nickel, copper, and platinum compounds, J. M. Robertson, J. Chem. Soc., 1935,615, An X-ray study of the phthalocyanines. Part II. Quantitative structure determination of the metal-free compound, J. M. Robertson, J. Chem. Soc., 1936, 1195 An X-ray study of the phthalocyanines. Part III. Quantitative structure determination of nickel phthalocyanine, J. M. Robertson and I. Woodward, J. Chem. Soc., 1937, 219 An X-ray study of the phthalocyanines. Part IV. Direct quantitative analysis of the platinum compound, J. M. Robertson and I. Woodward, J. Chem. Soc., 1940, 36. 

Khene et al. [7] used Ordinary Pyrolytic Graphite (OPG) coated with both as-prepared and activated NiPc, NiPc(OH)4 and polyNi(OH)Pc(OH)4, respectively. At the NiPc(OH)4/OPG electrode oligomers fouled the electrode surface, while with polyNi(OH)Pc(OH)4/OPG higher currents for the oxidation of 4-CP were observed, although with a shift to more positive potentials. As said above, the authors concluded that the activation led to a catalytic O-Ni-O bridged structure of the nickel phthalocyanine films. 

Phthalocyanine was discovered by accident in 1907 when Braun and Tchemiac isolated a small amount of blue precipitate after heating o-cyanobenzamide in alcohol [41]. The chemical structure of phthalocyanine was established by Robertson and co-workers who reported the X-ray single crystal structures of nickel phthalocyanine, copper phthalocyanine and platinum phthalocyanine [42-45]. Phthalocyanines show intense... 

At present, synthetic routes to more than 40 metal complexes other than the copper complex are known. Apart from a cobalt phthalocyanine pigment (P.B.75) which was introduced to the market just recently, none of the resulting products, however, has stimulated commercial interest as a pigment. Nickel complexes, however, are found in reactive dyes, while cobalt complexes of this basic structure are employed as developing dyes. 

The first structural report on a phthalocyanine complex concerned [Ni(pc)J (Table 110 I).2878 In the crystal lattice of this compound the square planar macrocycles are arrayed in slipped stacks such that the distance between the molecular planes along the perpendicular direction is 388 pm. [Ni(pc)] may be prepared by a variety of methods 2873,2871 2880 a convenient one is heating a foil of elemental nickel in o-cyanobenzamide at 270 °C (Scheme 60).2881 [Ni(pc)] is insoluble in the most common organic solvents, but soluble in concentrated sulfuric acid from which it is reprecipitated unchanged upon dilution. This complex is thermally very stable and may be sublimed in vacuo. The reduction of [Ni(pc)] can be accomplished by chemical or electrochemical methods and results in ligand-based reduced anions [Ni(pc)]" ( = 1, 2). Analogously, the electrochemical oxidation results in the oxidized ligand. 3... 

The insolubilities of phthalocyanines made their analysis difficult and it took some time before a satisfactory structure was elucidated. Initial work was undertaken by the Linstead group at Imperial College in the 1930s that culminated in a series of six back to back papers published in 1934 [14], It was also Linstead who named the compounds in recognition of their synthesis from phthalic anhydride and similarity to the blue cyanine dyes. Definitive characterization of the nickel, platinum and copper phthalocyanine complexes, together with the metal-free compound, was revealed in 1935 following the publication of their X-ray structures by Robertson [15] the copper and metal-free compounds are illustrated in Fig. 7.5. 

Robertson JM (1935) An X-ray study of the structure of the phthalocyanines. Part I. The metal-free, nickel, copper, and platinum compounds. J Chem Soc 615-621... 

In order to increase the solubility of porphyrin and phthalocyanine complexes, several structural modifications have been made, a, jS, y, 6-Tetra-(4-pyridyl)-porphin complexes of copper(II), nickel(II), and zinc(II) have been synthesized (35) and their ultraviolet spectra determined in chloroform and in acid solution. By utilizing sulfonic acid groups to increase solubility, complexes of 4,4, 4",4" -tetrasulfophthalocyanine complexes of many metals were prepared (94j 95). This chelating agent was found to have a ligand field strength comparable to cyanide (94y 95). 

STS has also been applied to a study of the unoccupied surface states of graphite [249], hydrogen-like image states on clean and oxygen-covered nickel and on gold epitaxed on silicon (111) [266], [267], the superconducting energy gap in NbsSn [268], the electronic structure of the InP (110) surface [245], and copper phthalocyanine adsorbed on Cu (100) [269]. 

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