Cu supported on mesoporous ceria: water gas shift activity at low Cu loadings through metal-support interactions.

We have synthesized and tested a highly active Cu doped mesoporous CeO2 catalyst system for the low temperature water-gas shift (WGS) reaction. While typical oxide-supported copper WGS catalysts are characterized by high copper loadings (30-40%), the morphological properties of the mesoporous CeO2 material enable high catalytic activity at copper loadings as low as 1%. Operando X-ray diffraction, in situ X-ray absorption near-edge structure spectroscopy (XANES), and operando diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) methods were used to probe the interactions between the metal and mesoporous oxide components under reaction conditions. Copper was observed to undergo reduction from oxide to metal under WGS conditions at 150 °C, while the CeO2 lattice was observed to expand upon heating, indicating Ce3+ formation correlated with CO2 production. The active state of the catalysts was confirmed by in situ XANES to contain Cu0 and partially reduced CeO2. DRIFTS analysis revealed carboxyl species bound to copper during reduction, as well as formate and carbonate surface species on ceria. Lower concentrations of copper were observed to foster enhanced metal-support interactions.

N-(4-Bromo-phen-yl)acetamide: a new polymorph.

A new polymorph of the title compound, C8H8BrNO, has been determined at 173 K in the space group P21/c. The previous room-temperature structure was reported to crystallize in the ortho-rhom-bic space group Pna21 [Andreetti et al. (1968 ▶). Acta Cryst. B24, 1195-1198]. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds forming chains along [010]. Weak C-H⋯π inter-actions are also present.

Redetermination of loperamide monohydrate.

The structure of the title compound {systematic name: 4-[4-(4-chloro-phen-yl)-4-hy-droxy-piperidin-1-yl]-N,N-dimethyl-2,2-di-phenyl-butanamide monohydrate}, C(29)H(33)ClN(2)O(2)·H(2)O, has been redetermined at 170 (2) K. The redetermination is of significantly higher precision than the previous structure determination at room temperature and includes the H-atom coordinates that were not included in the previous report [Germain et al. (1977 ▶). Acta Cryst. B33, 942-944]. It consists of a piperidin-1-yl ring in a distorted chair conformation, with the N,N-dimethyl-α,α-diphenyl-butyramide and the 4-chloro-phenyl and hy-droxy groups bonded in para positions and an external water mol-ecule within the asymmetric unit. The dihedral angles between the mean plane of the piperidine ring and the 4-chloro-phenyl and two benzene rings are 83.4 (5), 76.4 (2) and 85.9 (2)°, respectively. The two benzene rings are inclined to one another by 50.8 (6)°. In the crystal, mol-ecules are linked by O-H⋯O and O-H⋯N hydrogen bonds and weak C-H⋯O intermolecular interactions, forming an infinite two-dimensional network along [110].

3,5-Bis(4-fluoro-phen-yl)-1-phenyl-4,5-dihydro-1H-pyrazole.

In the title compound, C(21)H(16)F(2)N(2), the dihedral angle between the fluoro-phenyl groups is 66.34 (8)°, and the dihedral angle between the envelope-configured pyrazole group (N/N/C/C/C) and the benzene ring is 11.50 (9)°. The dihedral angles between the benzene and the two fluoro-substituted phenyl groups are 77.7 (6) and 16.7 (5)°. Weak C-H⋯π interactions contribute to the stability of the crystal structure.

(E)-3-(4-Meth-oxy-phen-yl)-1-[4-(piperidin-1-yl)phen-yl]prop-2-en-1-one.

The piperidine ring in the title compound, C(21)H(23)NO(2), is in a slightly distorted chair conformation. The dihedral angle between the two benzene rings is 5.6 (4)°. The dihedral angles between the propenone unit and the benzene and meth-oxy-substituted benzene rings are 5.6 (7) and 10.7 (8)°, respectively. Weak inter-molecular C-H⋯O hydrogen bonds and weak C-H⋯π inter-actions contribute to the stability of the crystal structure.

2,3-Dibromo-1,3-bis-(4-fluoro-phen-yl)propan-1-one.

In the title compound, C(15)H(10)Br(2)F(2)O, the dihedral angle between the two 3-fluoro-substituted benzene rings is 5.7 (5)°. The two bromine substituents on the chalcone moiety are close to anti as the Br-C-C-Br torsion angle is 176.9 (7)°. Weak C-Br⋯π inter-actions may contribute to the crystal stability.

(1E)-1-(3-Bromo-phen-yl)ethanone 2,4-di-nitro-phenyl-hydrazone.

The title compound, C(14)H(11)BrN(4)O(4), contains 3-bromo-phenyl and 2,4-dinitro-phenyl groups on opposite sides of a hydrazone unit and crystallizes with two mol-ecules in the asymmetric unit. The dihedral angles between the two ring systems in each mol-ecule are 2.0 (1) and 2.5 (4)°. Weak C-H⋯O hydrogen bonds and weak π-π stacking inter-actions [centroid-centroid distance = 3.7269 (14) Å] help to establish the packing. Intra-molecular N-H⋯O hydrogen bonds are also observed. On one of the rings, the Br atom is disordered over two equivalent positions of the phenyl ring [occupancy ratio 0.8734 (10):0.1266 (10).