Crystalline nanosheets of three-dimensional supramolecular frameworks with uniform thickness and high stability.

Fabricating three dimensional (3D) supramolecular frameworks (SMFs) into stable crystalline nanosheets remains a great challenge due to the homogeneous and weak inter-building block interactions along 3D directions. Herein, crystalline nanosheets of a 3D SMF with a uniform thickness of 4.8 ± 0.1 nm immobilized with Pt nanocrystals on the surface (Q[8]/Pt NSs) were fabricated via the solid-liquid reaction between cucurbit[8]uril/H2PtCl6 single crystals and hydrazine hydrate with the help of gas and heat yielded during the reaction process. A series of experiments and theoretical calculations reveal the ultrahigh stability of Q[8]/Pt NSs due to the high density hydrogen bonding interaction among neighboring Q[8] molecules. This in turn endows Q[8]/Pt NSs with excellent photocatalytic and continuous thermocatalytic CO oxidation performance, representing the thus-far reported best Pt nano-material-based catalysts.

Hydrophobic Trinuclear Copper Cluster-Containing Organic Framework for Synergetic Electrocatalytic Synthesis of Amino Acids.

Electrocatalytic synthesis of amino acids provides a promising green and efficient pathway to manufacture the basic substances of life. Herein, reaction of 2,5-perfluroalkyl-terepthalohydrazide and tris(4-µ2 -O-carboxaldehyde-pyrazolato-N, N')-tricopper affords a crystalline trinuclear copper cluster-containing organic framework, named F-Cu3 -OF. Incorporation of abundant hydrophobic perfluroalkyl groups inside the channels of F-Cu3 -OF is revealed to successfully suppress the hydrogen evolution reaction via preventing H+ cation with large polarity from the framework of F-Cu3 -OF and in turn increasing the adsorption of other substrates with relatively small polarity like NO3 - and keto acids on the active sites. The copper atoms with short distance in the trinuclear copper clusters of F-Cu3 -OF enable simultaneous activization of NO3 - and keto acids, facilitating the following synergistic and efficient C─N coupling on the basis of in situ spectroscopic investigations together with theoretical calculation. Combination of these effects leads to efficient electroproduction of various amino acids including glycine, alanine, leucine, valine, and phenylalanine from NO3 - and keto acids with a Faraday efficiency of 42%-71% and a yield of 187-957 µmol cm-2 h-1 , representing the thus far best performance. This work shall be helpful for developing economical, eco-friendly, and high-efficiency strategy for the production of amino acids and other life substances.

Post-Nickelation of a Crystalline Trinuclear Copper Organic Framework for Synergistic Photocatalytic Carbon Dioxide Conversion.

Rational regulation of electronic structures and functionalities of framework materials still remains challenging. Herein, reaction of 4,4',4''-nitrilo-tribenzhydrazide with tris(µ2 -4-carboxaldehyde-pyrazolato-N,N')-tricopper (Cu3 Py3 ) generates the crystalline copper organic framework USTB-11(Cu). Post-modification with divalent nickel ions affords the heterometallic framework USTB-11(Cu,Ni). Powder X-ray diffraction and theoretical simulations reveal their two-dimensional hexagonal structure geometry. A series of advanced spectroscopic techniques disclose the mixed CuI /CuII state nature of Cu3 Py3 in USTB-11(Cu,Ni) with a uniform bistable Cu3 4+ (CuI 2 CuII ) : Cu3 5+ (CuI CuII 2 ) (ca. 1 : 3) oxidation state, resulting in a significantly improved formation efficiency of the charge-separation state. This endows the Ni sites with enhanced activity and USTB-11(Cu,Ni) with outstanding photocatalytic CO2 to CO performance with a conversion rate of 22 130 µmol g-1 h-1 and selectivity of 98 %.

Two-Dimensional Porphyrin-Based Covalent Organic Framework with Enlarged Inter-layer Spacing for Tunable Photocatalytic CO2 Reduction.

Two-dimensional (2D) porphyrin-based covalent organic frameworks (COFs) are one of the most promising candidates for photocatalytic carbon dioxide reduction reaction (CO2RR), which however still suffer from the hindered mass transfer during the catalysis procedure associated with the close packing of 2D COF layers due to the strong axial π-π stacking. Herein, condensation between the porphyrinic aldehydes p-MPor-CHO (M = H2, Co, and Ni) and 3,8-diamino-6-phenyl-phenanthridine (DPP) affords new porphyrin-based 2D COF architecture MPor-DPP-COFs (M = H2, Co, and Ni). The bulky phenyl substituent at the phenanthridine periphery of the linking unit reduces the axial π-π stacking, providing an enlarged inter-layer spacing of 6.0 Å according to high-resolution transmission electron microscopy. This, in combination with the large surface area (1021 m2 g-1) revealed by nitrogen sorption measurements at 77 K for CoPor-DPP-COF possessing electroactive Co ions, endows it with excellent photocatalytic activity for CO2RR with a CO generation rate of 10 200 µmol g-1 h-1 and a CO selectivity up to 82%. This work affords new ideas for achieving efficient photocatalytic CO2RR upon fine-tuning the inter-layer spacing of 2D COFs.