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- Metal Azolate/Carboxylate Frameworks as Catalysts in Oxidative and C-C Coupling ReactionsPublication . Tabacaru, Aurel; Xhaferaj, Nertil; Martins, Luisa; Alegria, Elisabete; Chay, Rogério; Giacobbe, Carlotta; Domasevitch, Konstantin V.; Pombeiro, Armando; GALLI, SIMONA; Pettinari, ClaudioThe five metal azolate/carboxylate (MAC) compounds [Cd(dmpzc)(DMF)(H2O)] (Cd-d.mpzc), [Pd-(H(2)dmpzc)(2)Cl-2] (Pd.dmpzc), [Cu(Hdmpzc)(2)] (Cu-dmpzc), [Zn4O(dmpzc)(3)]-Solv (Zn-dmpzcS), and [Co4O(dmpz(3)]-Solv (Co-dinpzcS) were isolated by coupling 3,5-dimethy1-1H-pyrazol-4-carboxylic acid (H(2)dmpzc) to cadmium(II), palladium(II), copper(II), zinc(II), and cobalt(II) salts. While Cd-clinpzc and Pd-dmpzc had never been prepared in the past, for Cu-dmpzc, Zndmpzc"S, and Co-dmpzc"S we optimized alternative synthetic paths that, in the case of the copper(II) and cobalt(11) derivatives, are faster and grant higher yields than the previously reported ones. The crystal structure details were determined ab initio (Cd-dmpzc and Pd-dmpzc) or refined (Cu-dmpzc, Zn-dmpzc"S, and Co-dmpzc-S) by means of powder X-ray diffraction (PXRD). While Cd-dmpzc is a nonporous 3D MAC framework, Pddmpzc shows a 3D hybrid coordination/hydrogen-bonded network, in which Pd(H(2)dmpzc)(2)Cl-2 monomers are present. The thermal behavior of the five MAC compounds was investigated by coupling thermal analysis to variable-temperature PXRD. Their catalytic activity was assessed in oxidative and C C coupling reactions, with the copper(II) and cadmium(II) derivatives being the first nonporous MAC frameworks to be tested as catalysts. Cu-dmpzc is the most active catalyst in the partial oxidation of cydohexane by tert-butyl hydropermdde in acetonitrile (yields up to 12% after 9 h) and is remarkably active in the solvent-free microwave-assisted oxidation of 1-phenylethanol to acetophenone (yields up to 99% at 120 degrees C in only 0.5 h). On the other hand, activated Zn-dmpzc"S (Zn-dmpzc) is the most active catalyst in the Henry C C coupling reaction of aromatic aldehydes with nitroethane, showing appreciable diastereoselectivity toward the syn-nitroalkanol isomer (syn:anti selectivity up to 79:21).
- Novel coordination polymers with (Pyrazolato)-based tectons: catalytic activity in the peroxidative oxidation of alcohols and cyclohexanePublication . Timokhin, Ivan; Pettinari, Claudio; Marchetti, Fabio; Pettinari, Riccardo; CONDELLO, Francesca; GALLI, SIMONA; Alegria, Elisabete; Martins, Luisa; Pombeiro, ArmandoCoupling five rigid or flexible bis(pyrazolato)based tectons with late transition metal ions allowed us to isolate 18 coordination polymers (CPs). As assessed by thermal analysis, all of them possess a remarkable thermal stability, their decomposition temperatures lying in the range of 340-500 degrees C. As demonstrated by N-2 adsorption measurements at 77 K, their Langmuir specific surface areas span the rather vast range of 135-1758 m(2)/g, in agreement with the porous or dense polymeric architectures retrieved by powder X-ray diffraction structure solution methods. Two representative families of CPs, built up with either rigid or flexible spacers, were tested as catalysts in (0 the microwave-assisted solvent-free peroxidative oxidation of alcohols by t-BuOOH, and (ii) the peroxidative oxidation of cydohexane to cydohexanol and cydohexanone by H2O2 in acetonitrile. Those CPs bearing the rigid spacer, concurrently possessing higher specific surface areas, are more active than the corresponding ones with the flexible spacer. Moreover, the two copper(I)-containing CPs investigated exhibit the highest efficiency in both reactions, leading selectively to a maximum product yield of 92% (and TON up to 1.5 x 10(3)) in the oxidation of 1-phenylethanol and of 11% in the oxidation of cydohexane, the latter value being higher than that granted by the current industrial process.