An approach to transforming amorphous organic networks into crystalline covalent organic frameworks (COFs) with retention of the colloidal nanosize and uniform morphology is presented. Specifically, Fe O nanoclusters are encapsulated by a disordering polyimine network via the Schiff-base reaction. The formed imine bonds could be reconstructed under thermodynamic control to reform the polyimine networks into imine-linked COFs in situ. Such a core-shell microsphere exhibits the uniform size and spherical shape, controllable COF shell thickness, accessible surface modification, and improved solution dispersibility as well as maintenance of high surface area, periodic micropores, and superior magnetic responsiveness. Additionally, the photothermal conversion effect is demonstrated for the first time on the nanoCOF layers upon exposure to near infrared light, providing convincing evidence for potential use in phototherapy.

Ethylene dimerization was investigated by using an 84T cluster of faujasite zeolite modeled by the ONIOM3(MP2/6-311++G(d,p):HF/6-31G(d):UFF) method. Concerted and stepwise mechanisms were evaluated. In the stepwise mechanism, the reaction proceeds by protonation of ethylene to form the surface ethoxide and then C--C bond formation between the ethoxide and the second ethylene molecule to give the butoxide product. The first step is rate-determining and has an activation barrier of 30.06 kcal mol(-1). The ethoxide intermediate is rather reactive and readily reacts with another ethylene molecule with a smaller activation energy of 28.87 kcal mol(-1). In the concerted mechanism, the reaction occurs in one step of simultaneous protonation and C--C bond formation. The activation barrier is calculated to be 38.08 kcal mol(-1). Therefore, the stepwise mechanism should dominate in ethylene dimerization.

Anatase TiO2 nanosheets (TiO2-NS) and nanospindles (TiO2-NSP) have been successfully prepared with F– and glacial acetic acid as structure-directing agents, respectively. The Fe2O3/TiO2-NS and Fe2O3/TiO2-NSP nanocatalysts were prepared by a wet incipient impregnation method with a monolayer amount of Fe2O3. All the catalysts were employed for the selective catalytic reduction of NO with NH3 (NH3-SCR) in order to understand the morphology-dependent effects. It is interesting that the Fe2O3/TiO2-NS nanocatalyst exhibited better removal efficiency of NO x in the temperature range of 100–450 °C, which was attributed to more oxygen defects and active oxygen, acid sites, as well as adsorbed nitrate species based on Raman spectra, XPS, NH3-TPD, NO+O2-TPD, and in situ DRIFTS. The density functional theory (DFT) method was used to clarify the NO and NH3 adsorption abilities over the catalyst models of Fe2O3/TiO2{001} and Fe2O3/TiO2{101}. The results showed that the NH3 adsorption energy over the TiO2{001} (−2.00 eV) was lower than that over TiO2{101} (−1.21 eV), and the NO adsorption energy over TiO2{001} (−1.62 eV) was also lower than that over TiO2{101} (−0.29 eV), which agreed well with the experimental results that Fe2O3/TiO2-NS achieved higher catalytic activity than Fe2O3/TiO2-NSP for NH3-SCR of NO. In addition, the rapid electron transfer and regeneration of Fe3+ on the {001} facet of Fe2O3/TiO2-NS also promoted the NH3-SCR reaction efficiency. This work paves a way for understanding the facet–activity relationship of Fe2O3/TiO2 nanocatalysts in the NH3-SCR reaction.

CeO 2 nanorods impregnated with 2.5 atom % of NiO (NiO/ CeO 2 nanorods) were successfully synthesized and examined as catalysts for the NH 3 -selective catalytic reduction (NH 3 -SCR) of nitric oxide (NO). The catalytic activity of NiO/CeO 2 nanorods resulted in up to ∼90% NO conversion at 250 °C, which is superior to that of pure CeO 2 nanorods or NiO nanoparticles. Subsequently, extensive studies of the NiO/CeO 2 -catalyzed reduction of NO were conducted using X-ray photoelectron spectroscopy, hydrogen temperature-programmed reduction, temperature-programmed desorption, and density functional theory periodic calculations. Compared to that of the pure CeO 2 nanorods, the results demonstrated that the NiO/CeO 2 nanorods resulted in (i) a higher concentration of Ce 3+ chemical species, (ii) a larger amount of active O α , (iii) lower temperature reducibility, (iv) a lower amount of energy required for oxygen vacancy distortion, and (v) a significant adsorption of and strong interaction between NO and NH 3 molecules. Our findings therefore elucidated considerable details of the structural properties of the NiO/CeO 2 nanorods that were decisive for achieving a highly efficient conversion of NO by the NH 3 -SCR process at low temperatures.

A series of organic sensitizers with the direct electron injection mechanism and a high molar extinction coefficient comprising double donors, a π-spacer, and anchoring acceptor groups (D−D−π−A type) were synthesized and characterized by experimental and theoretical methods for dye-sensitized solar cells. (E)-2-Cyano-3-(5″-(4-((4-(3,6-di-tert-butylcarbazol-9-yl)phenyl)dodecylamino)phenyl)-[2,2′:5′,2″-terthiophene]-5-yl)acrylic acid showed performance with a maximal incident photon to electron conversion efficiency of 83%, J sc value of 10.89 mA cm −2 , V oc value of 0.70 V, and fill factor of 0.67, which correspond to an overall conversion efficiency of 5.12% under AM 1.5G illumination. The molecular geometry, electronic structure, and excited states were investigated with density functional theory, time-dependent density functional theory, and the symmetry-adapted cluster-configuration interaction method. The double donor moieties not only contribute to enhancement of the electron-donating ability, but also inhibit aggregation between dye molecules and prevent iodide/triiodide in the electrolyte from recombining with injected electrons in TiO 2 . Detailed assignments of the UV−vis spectra below the ionization threshold are given. The low-lying light-harvesting state has intramolecular charge transfer character with a high molar extinction coefficient because of the long π-spacer. Our experimental and theoretical findings support the potential of direct electron injection from the dye to TiO 2 in one step with electronic excitation for the present D− D−π−A sensitizers. The direct electron injection, inhibited aggregation, and high molar extinction coefficient may be the origin of the observed high efficiency. This type of D−D−π−A structure with direct electron injection would simplify the strategy for designing organic sensitizers.

In situ formed LiF grains are confined and evenly distributed throughout a covalent organic framework (COF) film, which exhibits cooperative effectiveness to greatly stabilize the lithium metal.

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An approach to transforming amorphous organic networks into crystalline covalent organic frameworks (COFs) with retention of the colloidal nanosize and uniform morphology is presented. Specifically,F e 3 O 4 nanoclusters are encapsulated by ad isordering polyimine network via the Schiff-base reaction. The formed imine bonds could be reconstructed under thermodynamic control to reform the polyimine networks into imine-linked COFs in situ. Suchacore-shell microsphere exhibits the uniform sizea nd spherical shape, controllable COF shell thickness,a ccessible surface modification, and improved solution dispersibility as well as maintenance of high surface area, periodic micropores,and superior magnetic responsiveness.A dditionally,t he photothermal conversion effect is demonstrated for the first time on the nanoCOF layers upon exposure to near infrared light, providing convincing evidence for potential use in phototherapy.Covalent organic frameworks (COFs) are two-or threedimensional crystalline porous polymers that originate from the topological polymerization of building blocks with predesigned geometry and symmetry by virtue of dynamic covalent bonds (e.g.i mine, [1] enamine, [2] hydrazine, [3] azine, [4] b-ketoenamine, [5] and boronate ester [6] ). This emerging family presents high and regular porosity,tunable pore size and pore wall chemistry,a nd structural predictability and stability. [7] These characteristics endow COFs with outstanding performances for aw ide-range of applications,s uch as gas storage, [8] heterogeneous catalysis, [9] luminescence, [10] optical sensing, [11] proton conduction, [12] and photoconduction. [13] Against this backdrop,t here has been significant interest very recently in the miniaturization of COFs to the nanometer scale, [14] for the sake of extending the applicability and enhancing the proper-ties of COFs.I ndeed, the nanoCOFs can overcome,t os ome extent, the poor solution properties of the corresponding bulk materials,and they have been developed into nanocarriers for biomedical applications,such as drug delivery [15] and enzyme immobilization. [14b] However,most of the materials described were not very compatible with biomedical and pharmaceutical applications,a nd, with few exceptions,t hey were not engineered as dispersible nanoparticles to enable in vivo circulation by intravenous administration. As far as is known, the COF assemblies are prepared with no way of controlling size and morphology under solvothermal conditions.