Palladium phthalocyanine

Palladiumphthalocyanine (PcPd) can be synthesized from phthalimide, ammonium molyb-date(VI), urea and palladium(II) chloride in nitrobenzene.285 Peripherally substituted palladium phthalocyanine is prepared by the reaction of phthalonitrile286 or isoindolinediimine114,117 and palladium(II) acetate in 2-(dimethylamino)ethanol. Also a metal insertion into metal-free phthalocyanine in dimethylfonnamide starting from bis(triphenylphos-phane)palladium(II) chloride has been performed.141,287... 

The palladium phthalocyanine (67), developed by Mitsui Toatsu and Ciba58,59 is one of the leading phthalocyanine infrared absorbers for CD-R (Compact Disk-Rewritable) (see Chapter 9.13). Bulky groups (R) reduce undesirable molecular aggregation, which lowers the extinction coefficient and hence the absorptivity and reflectivity. Partial bromination allows fine tuning of the film absorbance and improves reflectivity. The palladium atom influences the position of the absorption band, the photostability and the efficiency of the radiationless transition from the excited state.58 It is marketed by Ciba as Supergreen.60... 

Gaffo, L., C.J.L. Constantino, W.C. Moreira, R.F. Aroca, and O.N. Oliveira (2002). Vibrational spectra and surface-enhanced resonance Raman scattering of palladium phthalocyanine evaporated films. J. Raman Spectrosc. 33, 833. 

The adsorption of palladium phthalocyanine on the basal plane of graphite has been studied by STM and LEED under ultra high vacuum [20] and it was found that... 

Gopakumar TG, Lackinger M, Hackcat M, Miller F, Hietschold M (2004) Adsmption of palladium phthalocyanine on graphite STM and T.EED study. J Phys Chem B 108 7839-7843... 

The palladium(II) phthalocyanines are satisfactory singlet oxygen generators. Thus, f>A values for tetra-t-butylphthalocyanine ((27), with stated replacement for Mg) are 2H, 0.22 Zn, 0.34 Pd, 0.54, i.e., increasing in line with the heavy atom effect.180 For palladium(II) tetra-t-butylphthalocyanine ((27), Pd instead of Mg) in benzene at 290 K, 4>f= 0.048 and X = 0.49.180 However, palladium(II) 2,3-dihydroxy-9,16,23-tri-t-butylphthalocyanine was synthesized by a mixed condensation (1 9 mix of appropriate dinitriles) as a likely amphiphilic sensitizer, but did not show bioactivity in an enzyme assay, possibly because of aggregation.180... 

A mild aerobic palladium-catalyzed 1,4-diacetoxylation of conjugated dienes has been developed and is based on a multistep electron transfer46. The hydroquinone produced in each cycle of the palladium-catalyzed oxidation is reoxidized by air or molecular oxygen. The latter reoxidation requires a metal macrocycle as catalyst. In the aerobic process there are no side products formed except water, and the stoichiometry of the reaction is given in equation 19. Thus 1,3-cyclohexadiene is oxidized by molecular oxygen to diacetate 39 with the aid of the triple catalytic system Pd(II)—BQ—MLm where MLm is a metal macrocyclic complex such as cobalt tetraphenylporphyrin (Co(TPP)), cobalt salophen (Co(Salophen) or iron phthalocyanine (Fe(Pc)). The principle of this biomimetic aerobic oxidation is outlined in Scheme 8. 

Diimines such as bpy and phen replace 2-(arylazo)pyridine ligands (aap) in [Pd(aap)Cl2] by a simple second-order process, whose detailed mechanism may depend on the nature of the incoming ligand (254). Three phthalocyanine units, each containing Zn2+, can be bonded to tetrahedral phosphorus, to give [PPh(pc-Zn)3]+. Mechanistic proposals are advanced for this novel exchange reaction in which palladium-bound phthalocyanine replaces phenyl on phosphorus (255). 

An aluminum electrode modified by a chemically deposited palladium pen-tacyanonitrosylferrate film was reported in [33]. Vitreous carbon electrode modified with cobalt phthalocyanine was used in [34]. Electrocatalytic activity of nanos-tructured polymeric tetraruthenated porphyrin film was studied in [35]. Codeposition of Pt nanoparticles and Fe(III) species on glassy-carbon electrode resulted in significant catalytic activity in nitrite oxidation [36]. It was shown that the pho-tocatalytic oxidation at a Ti02/Ti film electrode can be electrochemically promoted [37]. 

Organo-iron and -cobalt phthalocyanines are reported to transfer the organic groups to palladium salts, and they have been used to substitute alkenes.46... 

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],... 

Diazaporphyrins - Like the phthalocyanines, a 10,20-diaza-porphinoid palladium complex was composed by cyclooligomerization. The condensation of two suitable bispyrrole halves yielded the tetrapyrrole complex, cis [1,11-dimethoxy-2,2,3,3,7,7,8,8,12,12,13,13,17,17,18,18-hexadecamethyl- 10,20-diaza-decahydro-porphyrinato]palladium(II) [124]. 

Zeolite-encapsulated Fe-phthalocyanine and Co-salophen catalysts were used in the palladium-catalyzed aerobic oxidation of hydroquinone to benzoquinone, in the oxidation of 1-octene to 2-octanone and in the allylic oxidation of cyclohexene to 3-acetoxycyclohexene. These catalysts proved to be active in the above reactions and they were stable towards selfoxidation and it was possible to reuse them in subsequent runs. The specific activity of the encapsulated Fe-phthalocyanine catalyst was about four times higher than those of the free complex. 

Palladium forms complexes such as the dithio-oxalate ion, Pd(N2S2H)2, glyoximes, and phthalocyanine which are structurally similar to the compounds of Ni and Pt, and also numerous bridged compounds. Early X-ray studies established the planar trans configuration of (d) and (e) ... 

Several metal macrocycles, like iron phthalocyanine and cobalt salophen were tested in these palladium-catalyzed aerobic oxidation of olefins and dienes. These tnacrocycles were able to activate the molecular oxygen, but in the homogeneous system several problems have arised, such as poor solubility, self-degradation and the difficulty to reuse theses complexes. A... 

Equations (II) to (IX) illustrate basic methods of preparation, but many variations are used, particularly in industry, to obtain an economic yield. Phthalic acid, phthalamide, phthalimide, and phthalic anhydride, together with urea, are often used instead of phthalonitrile, and catalysts such as ammonium molybdate or zirconium tetrachloride may be employed (249, 251, 269). The reaction between phthalonitrile and metals (finely divided or acid-etched) is usually very vigorous at 250°-300°C, sufficient heat being generated to maintain the reaction temperature. This is an illustration of the ease with which the phthalocyanine skeleton is formed. Even more surprising are the observations that palladium black (118) and gold (189) will dissolve in molten phthalonitrile. Reaction (III) between phthalonitrile and a finely divided metal, metal hydride, oxide, or chloride is perhaps the most generally employed. For the unstable phthalocyanine complexes such as that of silver (11), the double decomposition reaction... 

Palladium chlorophthalocyanine is formed when phthalonitrile is heated with palladous chloride. Like other nuclear halogen-substituted phthalocyanines, it will not sublime (11, 278). The unsubstituted derivative may be prepared by the dehydrogenation of tetracyclohexenotetrazaporphin with palladium black (113), or by the action of palladous chloride on lithium phthalocyanine in absolute alcohol (11). It is also possible to prepare the complex by dissolving palladium black in boiling phthalonitrile, a really remarkable reaction. 

Jones T A, Bott B, Hurst N W and Mann B 1983 Solid state gas sensors zinc oxide single crystals and metal phthalocyanine films Proc. Int. Meeting on Chemical Sensors (Analytical Chemistry Symposia Series 17, Fukuoda 1993) ed T Seiyama, K Fueki, J Shiokawa and S Suzuki (New York Elsevier) pp 90-4 Saeki H and Suzuki S 1992 Organic thin film semiconductor device Japanese Patent IPX 19881102 63-277732 US Patent 3 Q19 595 Lewis A 1967 The Palladium Hydrogen System (New York Academic)... 

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