Cobalt template synthesis

Complexes containing encapsulated metal ions (clathrochelates ) with the formula [M(dioxime)3(BR)2] are known with iron(II) 135, cobalt(ll) 136, cobalt(III) 137, and ruthenium(ll) 138 (Fig. 37) [205-220]. Generally, these macrobicyclic complexes are prepared by template synthesis from a mixture of... 

The Russell group has applied the template synthesis approach to nanoporous films generated from UV-treated PS-fo-PMMA copolymers [43, 147,233,235,241], which were pre-aligned perpendicular to the substrate by an electric field. Through direct current electrodeposition, they fabricated high-density vertical arrays of ferromagnetic cobalt nanowires (Fig. 10a) [43]. Through subsequent work, they also demonstrated the successful replication... 

Eujii Y, Matsutani K, Kikuchi K. Formation of a specific coordination cavity for a chiral amino-acid by template synthesis of a polymer Schiff-base cobalt(III) complex. Chem Commun 1985 415-417. 

Template reactions between malonaldehydes and diamines in the presence of copper(II), nickel(II) or cobalt(II) salts yield neutral macrocyclic complexes (equation 15).99-102 Both aliphatic102 and aromatic101 diamines can be used. In certain cases, non-macrocyclic intermediates can be isolated and subsequently converted into unsymmetrical macrocyclic complexes by reaction with a different diamine (Scheme ll).101 These methods are more versatile and more convenient than an earlier template reaction in which propynal replaces the malonaldehyde (equation 16).103 This latter method can also be used for the non-template synthesis of the macrocyclic ligand in relatively poor yield. A further variation on this reaction type allows the use of an enol ether (vinylogous ester), which provides more flexibility with respect to substituents (equation 17).104 The approach illustrated in equation (15), and Scheme 11 can be extended to include reactions of (3-diketones. The benzodiazepines, which result from reaction between 1,2-diaminobenzenes and (3-diketones, can also serve as precursors in the metal template reaction (Scheme 12).101 105 106 The macrocyclic complex product (46) in this sequence, being unsubstituted on the meso carbon atom, has been shown to undergo an electrochemical oxidative dimerization (equation 18).107... 

Fig. 8 Template synthesis of the cobalt(III) sepulchrate complex, [Coffl(sep)]3+. Step i complex formation and oxidation by air step ii Schiff base condensation step iii nucleophilic attack to the C=N double bond by the deprotonated forms of ammonia...

Cobalt(saiophen) encapsulated in zeolite. The template synthesis method was used for the preparation of the Co(salophen) /zeolite catalyst (salophen = N,N - Bis(salicylidene) -1,2-phenylenediamine). The Co - exchanged zeolite was prepared by stirring 6g of NaY zeolite and 0.9 g of Co(OAc)2 4 H2O, dissolved in 150 ml deionized water for 48 h at room temperature. The slurry was then filtered and the pink solid obtained was washed with deionized water and dried overnight at 523 K. 0.62 g salicylaldehyde was added to 6g of Co-exchanged zeolite. 0.28 g 1,2-phenylenediamine was dissolved in 20 ml of methanol and the solution was slowly added to the mixture of the zeolite and salicylaldehyde. Having added the solution, the reaction mixture was refluxed for 1 hour and then allowed to stand at room temperature overnight. The product was filtered, washed with methanol and dried. 

Fujii, Y. Kikuchi, K. Matsutani, K. Ota, K. Adachi, M. Syoji, M. Haneishi, I. Kuwana, Y. Template synthesis of polymer schiff base Cobalt (III) complex and formation of specific cavity for chiral amino acid. Chem. Lett. 1984,13, 1487-1490. 

Gold nanoparticles have also been chosen due to their high electronic conductivity, their thermod5mamically stable interface with C03O4, and the potential to catalyze electrochemical reactions at the nanoscale. Belcher et al. propose hybrid gold-cobalt oxide wires prepared by a virus-templated synthesis. The cell delivered 94% of its theoretical capacity at a rate of 1.12 C and 65% at a rate of 5.19 C. Thus, the authors evidenced that nanoscale battery components can be designed and assembled on the basis of biological principles [54]. 

The template synthesis of macrocyclic complexes rra 5-[M(L9)]" (M"" = Ni, Co +, Fe +) from 1-phenyl-1,2-propanedione and 1,3-diaminopropane occurs [44] according to Scheme 1-2. Reaction (1) represents the organic reaction prior to addition of a metal salt. When a methanolic solution of the latter is added to the reaction mixture, the metal-directed condensation is realised, producing the carbi-nolamine and final products. It is obvious that reaction (2) is a consequence of shifting the position of tautomeric equilibrium under the influence of a metal ion exclusively towards [M(L9)] , the latter subsequently being transformed into [M(L10)]"+. That the condensation reaction actually takes place within the metal coordination sphere has been demonstrated by the isolation of the corresponding cobalt(III) macrocyclic complexes with L9. 

Template synthesis of the related polyamide macrocycle H4L327, by selfcondensation of o-aminobenzoic add on nickel(II), cobalt(II), zinc(II) and copper(II) matrices, has been claimed [366] (Eq. 2.178). 

The [Co(en)3]3+ ion has been shown to be a useful template for the synthesis of unusual cobalt, aluminum, gallium, and magnesium phosphates exhibiting framework,632-637 layered638-641 and chain642 structures, as well as for the hydrothermal synthesis of novel zeolites643,644 and other framework structures such as molybdenum phosphates.645... 

The use of metal ions as templates for macrocycle synthesis has an obvious relevance to the understanding of how biological molecules are formed in vivo. The early synthesis of phthalocyanins from phthalonitrile in the presence of metal salts (89) has been followed by the use of Cu(II) salts as templates in the synthesis of copper complexes of etioporphyrin-I (32), tetraethoxycarbonylporphyrin (26), etioporphyrin-II (78), and coproporphyrin-II (81). Metal ions have also been used as templates in the synthesis of corrins, e.g., nickel and cobalt ions in the synthesis of tetradehydrocorrin complexes (64) and nickel ions to hold the two halves of a corrin ring system while cycliza-tion was effected (51), and other biological molecules (67, 76, 77). 

Interest in these ligands stems from a desire to synthesize improved analogues of the cobalamines 100). With this in mind, 2,6-diacetylpyridine was condensed with N,N,N- f ra(aminopropyl)amine in the presence of nickel(II) or eopper(II) to afford the complex of 105, Cobalt(II) and zinc(II) have also been employed as templating agents in the synthesis of 105 101). The reaction of the nickel(II) complex of 105 with acetone results in a dimeric complex, 106101), by a process that is well established for primary amines 102). 

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