A planar binuclear phthalocyanine and its dizinc and dicobalt derivatives, in which two phthalocyanine units share a common benzene ring, have been studied by spectroscopy, electrochemistry, and spectroelectrochemistry. Their Langmuir-Blodgett film-forming properties have been examined, and the results of molecular orbital calculations on these and related systems are also presented. The properties are compared with those of the corresponding mononuclear control molecules. UV-visible-near IR absorption and magnetic circular dichroism spectroscopies and cyclic and differential pulse voltammetry indicate that, in these compounds, two relatively independent chromophore units interact and therefore that the two phthalocyanine planes are not completely planar in solution. The electrochemical and spectroelectrochemical measurements show the formations of various mixed-valence oxidation and reduction species in the binuclear compounds. The nonmetalated and dizinc complexes exhibit both Si and S2 emission. The radiative lifetimes (r) of the dizinc complex are smaller than those of the metal-free binuclear derivative for both Si and S2 emission, while the quantum yields ( fa) are larger. Furthermore, for S2 emission, the fa and t values of the binuclear compounds are larger than those of the corresponding mononuclear control molecules. Molecular orbital calculations within the framework of the Pariser-Parr-Pople approximation reproduce the splitting of the Q absorption band and further show that the splitting becomes larger the smaller the size of the shared common aromatic unit. In monolayers spread on water, the metal-free binuclear complex appears to have a slipped-stack conformation, tilted from the airwater interface normal plane. In Langmuir-Blodgett films, it may form a slipped-stack molecular arrangement with the stacking axis parallel to the substrate and/or a flat-lying conformation on the substrate surface.

Abstract

RD-RI60 784 INTRANOLECULRR COUPLING IN NETAL-FRUE BINUICLEAR1/ PHTNALOCYRNINES(U) YORK UNIV DOUNSYIEN (ONTRRIO) DEPTThis document has been approved for public release and sale; its distribution is unlimited. 8510 31 007 SECURITY CLASSIFICATION OF THIS PAGE fte.n Dale

The syntheses of 3,4- and 4,5-diiodophthalonitriles are described. Coupling of the latter compound with Pd(PPh(3))(2)Cl(2) and 1-octyne, 1-heptyne, 1-hexyne, 1-pentyne, and 3,3-dimethyl-1-butyne gave a series of 4,5-dialkynylphthalonitriles. Hydrogenation of 4,5-bis(1-pentynyl)phthalonitrile and 4,5-bis(3,3-dimethyl-1-butynyl)phthalonitrile gave 4,5-dipentylphthalonitrile and 4,5-bis(3,3-dimethylbutyl)phthalonitriles. Condensation of the dialkynylphthalonitriles with lithium 1-pentoxide in 1-pentanol gave 2,3,9,10,16,17,23,24-octaalkynylphthalocyanines, while intervention of the intermediate dilithium phthalocyanines with zinc acetate gave the related zinc(II) phthalocyanines. (1)H NMR spectroscopy of these octaalkynylphthalocyanines exhibited large chemical shifts (1-2 ppm) of the internal and aromatic protons at concentrations ranging from 10(-)(2) to 10(-)(5) M and at temperatures from 27 to 147 degrees C. The effects of aggregation phenomena are discussed. The importance of reporting concentration and temperature values for NMR spectra of phthalocyanines is stressed.

Metal-free copper and cobalt(II) binuclear phthalocyanines, in which the two phthalocyanine nuclci are covalently linked through five-atom bridges, have been prepared and characterized. Some new metal-free, copper, cobalt(II), and zinc 2,9,16,23-tetraalkoxyphthalocyanines, some of which are extremely soluble in organic solvents, are described.

A series of benzyl-substituted phthalonitriles, substituted at the 3-, 4-, and 4,5-positions, underwent varied condensations with phthalonitrile to give a series of protected (monohydroxy- and polyhydroxyphthalocyaninato)zinc(II) derivatives which were readily cleaved to give several hydroxyphthalocyanines (ZnPc) (phthalocyanine phenol analogues). Their efficacy as sensitizers for the photodynamic therapy (PDT) of cancer was evaluated on the EMT-6 mammary tumor cell line. In vitro, the 2-hydroxy ZnPc (32) was the most active, followed by the 2,3- and 2,9-dihydroxy ZnPc (39 and 45), with the 2,9,16-trihydroxy ZnPc (33) exhibiting the least activity. In vivo, the monohydroxy derivative 32 and the 2,3-dihydroxy derivative 39 were both efficient in inducing tumor necrosis at 1 micromol kg-1, but complete tumor regression was poor, even at 2 micromol/kg. In contrast, the 2,9-dihydroxy isomer 45, at 2 micromol kg-1, induced tumor necrosis in all animals treated, with 75% complete regression. These results underline the importance of the position of the substituents on the Pc macrocycle to optimize tumor response and confirm the PDT potential of the unsymmetrical Pcs bearing functional groups on adjacent benzene rings.

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