NiPc complexes

In CuPc, ZnPc, and NiPc complexes the central metals are electrochem-... 

MPc complexes have been employed as catalytic components in microemulsions and as composite films for the analysis of phenols and organohalides. Rusling and coworkers reported on FePc/DDAB, CuPc/DDAB, CuTSPc/DDAB, NiPc/DDAB, NiTSPc-DDAB, ZnPc/DDAB or ZnPc/CTAB surfactant films , and Jiang et al. on CoTSPc/DDAB for use in catalyzed reduction of trichloroacetic acid (TCA) and other organohalides. The catalytic reduction of TCA was more efficient in the acetonitrile/water solvent mixture than in the microemul-sions . Table 7.1 shows that lower potentials were observed for catalysis of TCA on surfactant films containing NiPc complexes than for the corresponding CuPc species. 

It is clear from this review that it is not only M-N4 complexes containing electroactive central metal which show catalytic activity. Unmetalated complexes as well as Zn and Cu complexes, which show ring-based processes only, often show electrocatalytic behavior towards the detection of some of the pollutants discussed in this work. There has been controversy surrounding the electrocatalytic activity of NiP or NiPc complexes. It seems the Ni porphyrin complexes do exhibit the Ni /Ni couple (at high potential in solution and more readily in the polymeric state) which may be involved in the electrocatalytic reactions involving these complexes. The Ni /Ni couple has not been identified electrochemically for the NiPc complexes in solution, but has been implicated in catalysis as an adsorbed polymer. It would be of interest to determine the values of the couple on polymeric NiPc complexes. 

Once the Ni nanoparticles (NiNPs) are exposed to the alkaline medium, they react instantly to form converted into O-Ni-0 bridge [137], which are involved in electrocatalysis. Nickel phthalocyanine (NiPc) complexes also form O-Ni-O bridges following cyclic voltammetry cycling in basic media. When both NiPc and NiNPs were employed for electrocatalytic oxidation of amitrole, Fig. 36 [137], the oxidation potential on NiNP-GCE was found to be 0.93 V, a value 60 mV which was less positive than that on bare GCE. The NiNP-GCE (Fig. 36e) showed better electrocatalytic activity relative to the NiPc-GCE (Fig. 36d) as judged by the huge catalytic current observed for the former. The NiNP/NiPc-GCE (Fig. 36c) was not... 

Several metallophthalocyanines have been reported to be active toward the electroreduction of C02 in aqueous electrolyte especially when immobilized on an electrode surface.125-127 CoPc and, to a lesser extent, NiPc appear to be the most active phthalocyanine complexes in this respect. Several techniques have been used for their immobilization.128,129 In a typical experiment, controlled potential electrolysis conducted with such modified electrodes at —1.0 vs. SCE (pH 5) leads to CO as the major reduction product (rj = 60%) besides H2, although another study indicates that HCOO is mainly obtained.129 It has been more recently shown that the reduction selectivity is improved when the CoPc is incorporated in a polyvinyl pyridine membrane (ratio of CO to H2 around 6 at pH 5). This was ascribed to the nature of the membrane which is coordinative and weakly basic. The microenvironment around CoPc provided by partially protonated pyridine species was suggested to be important.130,131 The mechanism of C02 reduction on CoPc is thought to involve the initial formation of a hydride derivative followed by its reduction associated with the insertion of C02.128... 

Interesting results have been obtained using metallophthalocyanines supported on porous carbon gas diffusion electrodes.132-136 In the case of CoPc and NiPc, CO is formed with a current efficiency of almost 100%.135 With Sn, Pb, and In phthalocyanines, mainly HC02H is formed, while Cu and Ti phthalocyanines promote the formation of CH4. The reason why some metal Pc complexes give CO or CH4, while others yield HC02H, has been interpreted in terms of the electron configuration in the metal.137 A rather different type of reaction is the very recent demonstration of the simultaneous reduction of C02 and N02 to give urea (NH2)2CO, which can be achieved with an efficiency up to 40% at similar gas-diffusion electrode devices with a NiPc supported catalyst.138... 

The influence of the central atom is shown in Fig. 14. In all the chelates we have studied, this influence is strong. The compounds with iron as central atom show the greatest activity, followed by cobalt, nickel and copper. This is shown by comparing monomeric Pc, TAA and TDAP. The activity of NiPc, CuPc and CuTAA is so small that potentials below 600 mV are measured even with a load of 30 mA/g catalyst. With TDAP, the Cu complex is more active than the Ni complex. The Fe complex of TAA, which would have been particularly interesting, was unfortunately not available. These observations indicate that oxygen reduction proceeds at the central atom of the chelate. 

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. 

History. Braun and Tschemak [23] obtained phthalocyanine for the first time in 1907 as a byproduct of the preparation of o-cyanobenzamide from phthalimide and acetic anhydride. However, this discovery was of no special interest at the time. In 1927, de Diesbach and von der Weid prepared CuPc in 23 % yield by treating o-dibromobenzene with copper cyanide in pyridine [24], Instead of the colorless dinitriles, they obtained deep blue CuPc and observed the exceptional stability of their product to sulfuric acid, alkalis, and heat. The third observation of a phthalocyanine was made at Scottish Dyes, in 1929 [25], During the preparation of phthalimide from phthalic anhydride and ammonia in an enamel vessel, a greenish blue impurity appeared. Dunsworth and Drescher carried out a preliminary examination of the compound, which was analyzed as an iron complex. It was formed in a chipped region of the enamel with iron from the vessel. Further experiments yielded FePc, CuPc, and NiPc. It was soon realized that these products could be used as pigments or textile colorants. Linstead et al. at the University of London discovered the structure of phthalocyanines and developed improved synthetic methods for several metal phthalocyanines from 1929 to 1934 [1-11]. The important CuPc could not be protected by a patent, because it had been described earlier in the literature [23], Based on Linstead s work the structure of phthalocyanines was confirmed by several physicochemical measurements [26-32], Methods such as X-ray diffraction or electron microscopy verified the planarity of this macrocyclic system. Properties such as polymorphism, absorption spectra, magnetic and catalytic characteristics, oxidation and reduc-... 

Serum from SLE patients with immune complexes containing anti-DNA antibodies and DNA induced the production of IFN-a in normal blood leukocytes in vitro (C6, VI, V2). Anti-DNA antibodies were able to convert DNA motifs, such as the CpG-rich unmethylated DNA of a plasmid (V2), into a potent IFN-a inducer in natural IFN-a-producing cells (NIPCs). In the presence of viral infection, IFN-a is produced. IFN-a, as well as IL-12 and IFN-y, can help dendritic cells to activate naive autoimmune T cells, which subsequently stimulate B cells to produce autoantibodies (R12). Then the immune complexes form and act as endogenous IFN-a inducers. Thus a vicious cycle of sustained IFN-a secretion and generation of autoimmune T and B cells is established (R12). 

In the first step the metal ion is introduced into the zeolite pores by ion exchange or adsorption of a labile metal complex. In the second step the intermediate material is reacted with gaseous complexing ligands, such as 1,2-dicyanobenzene, to form a complex inside the pores that is too large to difiuse out Alternatively metal complexes can be directly encapsulated inside the zeolite cavities during hydrothermal synthesis, as has been shown for FePc, CoPc, NiPc and CuPc in zeolite X [224],... 

The results for the synthesis of an X type zeolite in the presence of FePc, CoPc, NiPc, and CuPc are shown in table 1. In all cases here the metal complex or metal complex solution was added to the aluminosilicate gel immediately after mixing the silicate and aluminate solutions. The mixture was magnetically stirred for 15 minutes before heating. The resulting crystals were washed with water extracted with pyridine and sublimed. The surface MPc complexes can not be removed by solvent extraction. However, vacuum sublimation appears to be completely effective for removing non-intrazeolite complexes. The product zeolites were various shades of blue but became a very pale blue-green after... 

Because of space limitations, we will only briefly discuss the most basic application in the area of porphyrin optical spectra. Much work has already been done in this area, both with TDDFT and related methods. The TDDFT applications include free base porphin and its ss-octahalogenated derivatives, the porphyrinato-porphyrazinato-zirconiumhV) complex, NiP, NiPz, NiTBP, and NiPc, zinc phthalocyanine, chlorophyll a, zinc complexes of porphyrin, tetraazaporphyrin, tetrabenzoporphyrin, phthalocyanine, phenylene-linked free-base and zinc porphyrin dimers, metal bis(porphyrin) complexes a series of porphyrin-type molecules, and many more. We refer to ref. 75 for an extensive discussion of TDDFT calculations on the spectra of porphyrins and porphyrazines, as well as their interpretation. For further theoretical work on porphyrines, we mention ref. 76 and other papers in that special issue. 

A mixed-valent dinickel monohydride 49 was found to react with bases ( BuOK, LiN(SiMe3)j) to produce dinickel(I) compounds 50 and 51, both of which feature a Ni(I)-Ni(I) bond (Scheme 10.21) [22]. Complex 50 features a triangular Ni P core with Ni(I)-Ni(I) bond length of 2.515(1) A (Entry 21, Table 10.2) while 51 features a fused Ni PC and NiPC bicyclic core, with a significantly shorter Ni(I)-Ni(I) bond (2.408(2) A) (Entry 22, Table 10.2) in comparison with that in 50. These reactions involve sequences of deprotonation, C-H/C-P bond activation, and C-H bond formation, although the mechanism is still ambiguous. 

On the other hand. Pcs are promising active materials for OFETs due to their stability, and have been studied widely for a long time. Among various metal complexes CuPc and NiPc show the best mobilities, but they are as low as 0.02 cm /Vs [117], values that are too low to be used instead of a-Si. Much effort has been put into improving OFET performance based on Pcs. A sandwich-type thin-film device consisting of two kinds of Pc metal complex displays a mobility of 0.11 cm /Vs [118]. The mobility of OFET based on single crystal CuPc is 1 cm /Vs, which is the highest reported value so far for Pc-based OFETs [119]. 

Metal complexes H2PC, CoPc, CuPc, FePc, MgPc, NiPc, PbPc Cu Vmercaptoundecanoic acid self-assembled monolayer NO2 [500 ppb] DIMP [100 ppb], DMMP... 

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