RESUMEN
The novel composite, Fe3O4@SiO2@mSiO2-PW12/Ag, was successfully prepared by in situ loading Ag nanoparticles (Ag NPs) on the surface of grafted phosphotungstate (denoted as PW12) Fe3O4@SiO2@mSiO2via a photoreduction deposition method. PW12 not only acts as a reducing agent and stabilizer for Ag NPs but also as a bridge to link Ag NPs and the SiO2 shell in the loading process. Its activity toward the photodegradation of methyl orange (MO) and photoreduction of Cr2O72- anions was evaluated. Experimental results showed that Fe3O4@SiO2@mSiO2-PW12/Ag with 5.3 wt% Ag loading and 18.65 wt% of PW12 exhibits the highest photocatalytic efficacy, and complete degradation of MO and 91.2% photoreduction of Cr(vi) were realized under simulated sunlight for 75 min, respectively. The enhanced catalytic activities of the composite are due to its high specific surface area, the synergistic effect among the components and the formation of a heterojunction of PW12/Ag. The possible enhanced photocatalytic mechanism is proposed. The catalyst is durable and can be easily recovered using a magnet for recycling without a significant loss of catalytic activity.
RESUMEN
Isostructural heterometallic diruthenium carbonates KM(H2O)6[M(H2O)2Ru2(CO3)4Cl2]·4H2O [M = Zn (1) and Mn (2)] were synthesized from the reaction of the precursors [Ru2(CO3)4Cl2](5-) and transitional metal ions in aqueous solution. Complexes 1 and 2 show layered structures in which Ru2(II,III) units are linked by four octahedral environment M(H2O)2(2+) ions in a cross fashion and vice versa giving a negative bimetallic square grid layer {M(H2O)2Ru2(CO3)4Cl2}n(3n-). M(H2O)6(2+) ions, linked by K(+) forming zigzag chain {KM(H2O)6}n(3+), are located in the void spaces between the layers. The adjacent bimetallic carbonate layers are connected with K-O and K-Cl bonds, and hydrogen bonding, forming a supramolecular 3D framework structure. Their magnetic properties were characterized in detail, and intralayer ferromagnetic coupling between the Ru2 dimer and Mn(2+) ion, as well as long-range ordering (Tc = 5.2 K) coexistence of domain movement behavior were observed for complex 2.
RESUMEN
Two hetero-metallic carbonates, namely KCd(H2O)3Ru2(CO3)4·4H2O (1) and KCd(H2O)3Ru2(CO3)4·3.5H2O (2), have been synthesized in a neutral aqueous solution. Both of the 3D dimensional structured complexes contain mixed-valent diruthenium(II,III) carbonate paddlewheel cores of Ru2(II,III)(CO3)4(3-) that are connected to each other in trans- or cis-modes by carbonate oxygen atoms, forming rectangular square-grid and isomeric parallelogram layers [Ru2(CO3)4]n(3n-) in 1 and 2, respectively. The reaction temperature is found to play an important role in directing the final products with particular topologies and their layered structural diversity is due to the various linking modes between the Ru2(CO3)4(3-) units. The magnetic studies show that ferromagnetic interactions are propagated between the diruthenium units in both complexes 1 and 2 but their magnetic properties differ at low temperatures, in which the trans linking mode parallelogram layer [Ru2(CO3)4]n(3n-) in complex 2 leads to long-range magnetic ordering below 4.0 K. However, no Curie ordering down to 1.8 K is detected for complex 1 containing the isomeric rectangle square-grid layer linking in the cis mode.
RESUMEN
A three-dimensional CO(3)(2-)-bridged Mn(II)-Ru(2)(II,III) complex, Mn(4)(H(2)O)(16)H[Ru(2)(CO(3))(4)](2)[Ru(2)(CO(3))(4)(H(2)O)(2)]·11H(2)O (1), was synthesized by self-assembling Ru(2)(CO(3))(4)(3-) paddle-wheel precursors and Mn(2+) cations. It contains an unprecedented layer [Ru(2)(CO(3))(4)](n)(3n-) with (4,4) network. The ferromagnetic coupling between spin centers results in ordering below 3.0 K.