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A sodium borosilicate controlled-release inhibitor has been prepared via calcination for suppressing carbon steel corrosion in simulated recirculating cooling water (SRCW). The synthesized inhibitor was mainly composed of B2O3 and SiO2, coupling with small quantities of NaB5O6(OH)43H2O and NaB5O85H2O crystals. The total boron concentration gradually increased to 250 mg L-1 during the 28 days of release (2 g inhibitor in 500 mL SRCW) at 50 °C. A higher controlled-released rate existed in acidic environments (pH 5) than in neutral environments (pH 7) and alkaline environments (pH 9). The potentiodynamic polarization and electrochemical impedance spectroscopy results indicated that the inhibitor showed a better anticorrosion performance in neutral and alkaline environments than in acidic environments. In addition, a passive film with a Fe-O-B structure formed on the carbon steel surface to prevent the attack of the corrosive ions. A passivation-pitting-repassivation process was detected in the passive film by electrochemical noise, which demonstrated that the passive film exhibited a self-healing capacity. Moreover, a potential corrosion risk under the film was detected under the passive film in alkaline environment after 21 days of immersion. According to the experiment results and the analysis results of the point defect model, we believed that the anticorrosion performance of the sodium borosilicate inhibitor was in the following order: pH 7 > pH 9 > pH 5. [ABSTRACT FROM AUTHOR]

The vastly increasing application of chiral Cp ligands in asymmetric catalysis results in growing demand for novel chiral Cp ligands. Herein, we report a new class of chiral Cp ligands based on 1,1'-spirobiindane, a privileged scaffold for chiral ligands and catalysts. The corresponding Rh complexes are shown to be excellent catalysts in asymmetric oxidative coupling reactions, providing axially chiral biaryls in 19-97% yields with up to 98:2 er. [ABSTRACT FROM AUTHOR]

Living ring-opening metathesis polymerization (ROMP) of a hydrophilic norbornene monomer (M4) was performed successfully in air at room temperature using Grubbs’ third generation (G3) catalyst as the initiator. ROMP was then used to copolymerize M4with a hydrophilic difunctional norbornene cross-linker to develop a rapid and efficient method for preparing hydrogels. Although intramolecular cyclization was observed under dilute conditions, the critical gelation behavior was found to agree with the mean-field theory of Flory and Stockmayer (FS theory) more consistently than that of conventional free radical polymerization systems. By changing the length of the primary polymer chains, the initial molar ratio between monomer and cross-linker, and the length of the cross-linker, the equilibrium swelling ratio and the corresponding mechanical properties of the resultant hydrogels were manipulated across a broad range. [ABSTRACT FROM AUTHOR]

Two low-energy minima of (H2O)21with very different H-bonding arrangements have been investigated with the B3LYP density functional and RIMP2 methods, as well as with the TIP4P, Dang−Chang, AMOEBA, and TTM2-F force fields. The AMOEBA and TTM2-F model potentials give an energy ordering that agrees with the results of the electronic structure calculations, while the TIP4P and Dang−Chang models give the opposite ordering. Insight into the role of many-body polarization for establishing the relative stability of the two isomers is provided by an n-body decomposition of the energies calculated using the various theoretical methods. [ABSTRACT FROM AUTHOR]

With solvent molecules participating in coordination systems, four new Mn IIcoordination polymers of the rigid ligand 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid (H 2BDC-Cl 4) have been obtained from different solvent media. Single-crystal X-ray analysis indicates that the coordination arrays of 1− 4vary from 1D fishbone or zigzag chain for 1or 2, 2D (4,4) layer for 3, to 3D SrAl 2coordination network for 4, respectively. In {[Mn(BDC-Cl 4)(py) 2(H 2O) 2](py) 2} n( 1) and {[Mn(BDC-Cl 4)(MeOH) 3](MeOH)} n( 2), pyridine/water (in 1) and MeOH (in 2) molecules act as the monodentate terminal ligands to fulfill the metal coordination spheres. In the case of {[Mn(BDC-Cl 4)(dioxane)(H 2O) 2](dioxane)} n( 3), the aqua ligand is monodentate and the dioxane moiety displays unusual bridging bidentate mode, whereas for [Mn 5(BDC-Cl 4) 5(DMF) 5] n( 4), three Mn IIcenters are connected by four BDC-Cl 4ligands and two DMF molecules to constitute a trimeric unit. These secondary units are extended to the final 3D network with SrAl 2( sra) topology. Significantly, the solvents play an essential role in the crystallization and construction of these coordination frameworks with distinct dimensionality and connectivity. The thermal and photoluminescence properties of complexes 1− 4in the solid state have also been discussed. [ABSTRACT FROM AUTHOR]