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Photocatalytic CO2 reduction into carbonaceous feedstock chemicals is a promising renewable energy technology to convert solar energy and greenhouse gases into chemical fuels. Here, a covalent triazine‐based framework (CTF) is demonstrated as an efficient cocatalyst to reduce CO2 under visible‐light irradiation. The nitrogen‐rich triazine moieties in CTF contribute to CO2 adsorption, while the periodical pore structure of CTF favors the accommodation of CO2 and electron mediator. Immobilization of cobalt species onto CTF promotes the photocatalytic activity with a 44‐fold enhancement over pristine CTF and the optimal CO production rate of the obtained Co/CTFs was up to 50 μmol g−1 h−1. The results of solid‐state UV‐vis diffuse reflectance spectra (UV‐vis DRS), CO2 adsorption and electrochemical impedance spectroscopy (EIS) illustrated that the increased activity was ascribed to the enhanced CO2 capture capacity, improved absorption of visible‐light and facilitated the transfer of charge from CTF to CO2 molecules. The CTF not only serves as a substrate for active Co species, but also bridges the photosensitizer with cobalt catalytic sites for the efficient transfer of photoexcited electrons. This work highlights the capability and ease of fabricating covalent organic framework‐based photocatalytic systems that are potentially useful for energy‐conversion applications. [ABSTRACT FROM AUTHOR]

Three ionic nitrogen-containing chelating ligands ( L1- L3) are synthesized readily through alkylation and quaternization of 2,2′-dipyridylamine. The charge distributions and natural bond orbital analyses of their cations are implemented by using density functional theory calculations. The catalytic performances of their water-soluble palladium complexes are evaluated preliminarily by using the Suzuki-Miyaura cross-coupling reaction, and high catalytic activities of aryl bromides and chlorides are achieved in neat water. The mercury drop test, poison experiments, and TEM analysis are used to demonstrate the formation of palladium nanoparticles (NPs) after the catalytic reaction. The effects of pendant ionic groups in L1- L3 on the catalytic activities and structures of the palladium NPs are disclosed. These NPs are stable in water for several weeks; they are stabilized by synergetic interactions between the chelating coordination of the 2,2′-dipyridylamino group to the surface of the palladium NPs and the electrostatic repulsion of the ionic groups in L1- L3. [ABSTRACT FROM AUTHOR]

The reaction of bis- or tris-chelating nitrogen-containing ligands (L1-L5) with CuI gave rise to five coordination complexes consisting of Cu2I2 dimeric units. L1 in complex 1 adopts a cis conformation and links Cu2I2 into a dinuclear structure. L2 and L3 in complexes 2 and 3 exhibit a trans conformation, and the alternative linkage of L2 or L3 and Cu2I2 results in the formation of a 1D chain. In complex 4, two pyrazolyl-pyridine units of L4 at the same side of the central phenyl ring are connected to Cu2I2 forming a tetranuclear macrocycle, and the third pyrazolyl-pyridine unit at the other side of the central phenyl ring further links the macrocycle into a 1D chain. L5 bridges Cu2I2 in a cis conformation forming a tetranuclear complex, which is very different from 1 owing to the difference of the electronic property between pyrazolyl and triazolyl rings. The coordination nitrogen atoms in two pairs of ortho-positioned nitrogen-containing chelating rings in L1 and L5 are directed toward opposite and the same directions, respectively. Complexes 1- 4 containing pyrazolyl-pyridine units showed luminescence whereas no clear emission was observed in complex 5 containing triazolyl-pyridine units, despite the fact that they were investigated under the same conditions. The application of complexes 1- 5 in the copper(I)-catalyzed Ullmann cross-coupling reaction and azide-alkyne cycloaddition reaction was preliminarily evaluated. [ABSTRACT FROM AUTHOR]

The reaction of bis- or tris-chelating nitrogen-containing ligands (L1-L5) with CuI gave rise to five coordination complexes consisting of Cu 2 I 2 dimeric units. L1 in complex 1 adopts a cis conformation and links Cu 2 I 2 into a dinuclear structure. L2 and L3 in complexes 2 and 3 exhibit a trans conformation, and the alternative linkage of L2 or L3 and Cu 2 I 2 results in the formation of a 1D chain. In complex 4, two pyrazolyl-pyridine units of L4 at the same side of the central phenyl ring are connected to Cu 2 I 2 forming a tetranuclear macrocycle, and the third pyrazolyl-pyridine unit at the other side of the central phenyl ring further links the macrocycle into a 1D chain. L5 bridges Cu 2 I 2 in a cis conformation forming a tetranuclear complex, which is very different from 1 owing to the difference of the electronic property between pyrazolyl and triazolyl rings. The coordination nitrogen atoms in two pairs of ortho-positioned nitrogen-containing chelating rings in L1 and L5 are directed toward opposite and the same directions, respectively. Complexes 1-4 containing pyrazolyl-pyridine units showed luminescence whereas no clear emission was observed in complex 5 containing triazolyl-pyridine units, despite the fact that they were investigated under the same conditions. The application of complexes 1-5 in the copper(I)-catalyzed Ullmann cross-coupling reaction and azide-alkyne cycloaddition reaction was preliminarily evaluated., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)