Metal tetrakis phthalocyanines

The third order optical susceptibility was measured for a series of transition metal tetrakis(cumylphenoxy)phthalocyanines at 1.064 pm. Metal substitution caused a dramatic variation in the third order susceptibility. The largest s were found in the Co, Ni, and Pt complexes. Metal substitution introduces low lying electronic states which can enhance the susceptibility in these phthalocyanines. A strategy for enhancing the figure of merit, x(3)/a> of centrosymmetric nonlinear optical materials is suggested. 

This paper is a more extensive survey of the influence of the metal on the hyperpolarizability of a series of the transition metal tetrakis(cumylphenoxy)-phthalocyanines (MPcCP4). The compounds chosen were those most closely related to PtPcCP4, the compound which showed the largest hyperpolarizibility in the previous study. Specifically, phthalocyanines substituted with the last four members of the first row transition metal series (Co, Ni, Cu, and Zn) and also with the Ni, Pd, Pt triad were prepared and studied. The near IR spectra of these tetrakis(cumylphenoxy)-phthalocyanines are briefly discussed. Speculation on how metal substitution can influence the third order susceptibility of a near centrosymmetric structure, like that of the phthalocyanines, is presented. 

Figure 1. The structure of the metal tetrakis(cumylphenoxy)phthalocyanine (MPcCP4).

Palladium, platinum, and silver pthalocyaninates - 5,6-Di-substituted isoindoles were condensed in the presence of Pd(acac)2 or PtCl2 to obtain soluble octa-alkoxy-substituted phthalocyaninato palladium(II) and platinum(II) complexes [121]. Tetrakis-(neopentyloxy) phthalocyaninatosilver(II) was obtained in high yield from AgN03 and the respective metal free phthalocyanine in DMF at 75 °C [122],... 

Gas sensor applications of hybrids based on MN4-MC and CNTs have also been described. Liang et al. [55] demonstrated the fabrication and application of 2,9,16,23-tetrakis(2,2,3,3-tetralluoropropoxy) metal(II) phthalocyanines functionalized carbon nanotubes (MWCNTs/TFPMPc, M=Co, Zn, Cu, Pb, Pd, and Ni) for NH3 detection. The self-assembly method based on the jt-jt interactions was used to modify the CNTs, subsequendy deposited on gold interdigitated electrodes by drop-dry technique (Fig. 8a). 

In a recent communication we reported that the third order nonlinear optical susceptibility of Pt, Pb, and H2 tetrakis(cumylphenoxy)phthalocyanines was large and varied substantially with the metal substituent. (1) The structure of these compounds is shown in Fig. 1. The susceptibility was measured by degenerate four-wave mixing at 1.064 pm, a wavelength far from the main absorption bands of phthalocyanines near 650 nm. The nonlinear susceptibility of the Pt phthalocyanine was about a factor of 9 larger than that of the Pb phthalocyanine and a factor of 45 larger than the metal free compound. 

The near IR spectra of the tetrakis(cumylphenoxy)phthalocyanines have not been reported before. The absorption in the Cu complex and one of the absorptions in the Co complex lie close to bands which have been tentatively assigned to trip-multiplet transitions in other phthalocyanines.(14) However, the other absorption bands shown in Table 1 have not been previously reported for phthalocyanines with no peripheral substitution. The small absorption cross sections of these bands in the cumylphenoxy phthalocyanines suggest that they are forbidden transitions. Possible assignments for these bands include a symmetry forbidden electronic transition (like the MLCT transitions in NiPc discussed above) becoming vibronically allowed, d-d transitions on the metal ion, or trip-multiplet transitions. Spectroscopic studies are in progress to provide a more definitive assignment of these absorptions. 

The contributions of optically forbidden electronic states to the x(3) of centrosymmetric structures are of particular interest. (18) Each of the terms in a sum-over-states calculation of x(3) involves the product of transition moments between a sequence of four states. There are symmetry selection rules that govern which states which can contribute to the individual terms. In a centrosymmetric molecule the symmetry of the contributing states must be in a sequence g -> u --> g --> u --> g.(19) This means that all the non-zero terms in the summation which determines the hyperpolarizibility must include an excited electronic state of g symmetry (or the ground state) as an intermediate state. The tetrakis(cumylphenoxy)phthalocyanines are approximately centrosymmetric and many of the new electronic states in a metal phthalocyanine will be of g symmetry. Such states may well contribute to the dependence of the hyperpolarizibility on metal substitution. 

In some cases the authors detected, using spectroscopic techniques, that the incorporation of metal ions in the phthalocyanine and porphyrin systems weakens their interaction with the nanotube sidewalls. For example, [Zn(porphyrin)] and [Cu(phthalocyanine)] showed a weaker binding ability to SWCNTs than that of metal-free molecules [82a], Similarly, the interactions of THPP [5,10,15,20-tetrakis(hexadecyloxyphenyl)—21/7, 23//-porphine] with CNTs were apparently specific to the porphyrin-free base and were hindered upon Zn chelation [82b],... 

This instrument was employed to examine the excited state dynamics of supramolecular systems generated from self-assemblies between metal-substituted 18-crown-6 tetra-substituted phthalocyanines (McrPc) with ions contained in the crown sites (McrPcK) and metal-substituted weso-tetrakis(4-sulfonatophenyl)porphyrin (MTPPS) or meso-(4-carboxylphenyl)porphyrin (MTPPC). In the absence of added potassium ions, no hetero-complexes were formed. In the presence of K", absorption spectral changes indicated the formation of a... 

Trogler WC (2012) Chemical sensing with semiconducting metal phthalocyanines. Struct Bond 142 91-118 Walsh CJ, Mandal BK (2000) A novel method for the peripheral modification of phthalocyanines. Synthesis and third-order nonlinear optical absorption of p-tetrakis(2,3,4,5,6-pentaphenylbenzene)phthalocyanine. Chem Mater 12 287-289... 

Several nonprecious metals porphyrins and phthalocyanines were used to prepare graphene composites in order to investigate ORR [88], with Co being the most used metal. Cobalt tetrakis(o-aminophenyl)porphyrin, CoToAPP, was covalently anchored to graphene— besides other carbon nanomaterials—showing excellent electrocatalytic effect and efficient electrocatalytic performance for the ORR [89]. 

Because in most cases no clear lUPAC nomenclature exists for metal-containing macromolecules or macromolecular metal complexes, it is not possible to obtain by a Chemical Abstract literature search a detailed information on them. One has to look for each individual metal, metal ion, metal complex, metal chelate, ligand or also polymer. For type I usually rational nomenclature is used (for example cobalt(II) complex with/ of poly(4-vinylpyridine) or 2,9,16,23-tetrakis(4-hydroxyphenyl)phthalocyanine zinc(II)... 

The slowness of formation and dissociation of metal complexes of rigid tetraazamacrocycles such as porphyrins and phthalocyanines has long been recognized, but is still being investigated and quantified. Recent examples of kinetic studies in this area include the displacement of tetrakis(4-sulfonato-phenyl)porphyrin from Gd " by edta, " of tetrakis(iV-methyl-4-pyridyl) porphyrin from Ln " (Ln = Yb, Dy, Gd, Sm, Nd) again by edta, and of dechelation of tetraphenylporphyrin from acetato-, chloro-, and bromo-derivatives of Sc " and y " ", of Eu , Gd ", and and of Ti " "... 

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