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By using a catalytic amount of a porphyrin‐based covalent organic framework (Por‐Ad‐COF) as the efficient recyclable photocatalyst, the photocatalytic oxidative [3+2] cycloaddition reaction between tetrahydroisoquinolines and N‐substituted maleimides was developed under aerobic conditions at room temperature. Various substituted pyrrolo[2,1‐a]isoquinolines were obtained in moderate to good yields via the dipolar [3+2] cycloaddition and oxidative aromatization cascade process under visible light irradiation. This was the first example to employ the covalent organic framework as the heterogeneous photocatalyst to perform the photocatalytic dipolar [3+2] cycloaddition reaction for the synthesis of pyrrolo[2,1‐a]isoquinolines. [ABSTRACT FROM AUTHOR]

A supramolecular polymer was constructed from a light‐driven overcrowded alkene switch modified with two alkylated gallic acid amide pendants (MSP‐1). Upon UV irradiation, stable MSP‐1 isomerized into unstable MSP‐2, which induced the effective collapse of well‐defined cross‐linked supramolecular polymers, and the reassembly can be realized by aging at low temperature. [ABSTRACT FROM AUTHOR]

Nature uses hydrogenase enzyme to catalyze proton reduction at pH 7 with overpotentials and catalytic efficiencies that rival platinum electrodes. Over the past several years, [FeFe]-hydrogenase ([FeFe]-H2ase) mimics have been demonstrated to be effective catalysts for light-driven H2 evolution. However, it remains a significant challenge to realize H2 production by such an artificial photosynthetic system in neutral aqueous solution. Herein, we report a new system for photocatalytic H2 evolution working in a broad pH range, especially under neutral conditions. This unique system is consisted of branched polyethylenimine (PEI)-grafted [FeFe]-H2ase mimic (PEI- g-Fe2S2), MPA-CdSe quantum dots (MPA=mercaptopropionic acid), and ascorbic acid (H2A) in water. Due to the secondary coordination sphere of PEI, which has high buffering capacity and stabilizing ability, the system is able to produce H2 under visible-light irradiation with turnover number of 10 600 based on the Fe2S2 active site in PEI- g-Fe2S2. The stability and activity are much better than that of the same system under acidic or basic conditions and they are, to the best of our knowledge, the highest known to date for photocatalytic H2 evolution from a [FeFe]-H2ase mimic in neutral aqueous solution. [ABSTRACT FROM AUTHOR]

Lichtgetrieben: Wasserlösliche Poly(acrylsäure) ‐ Katalysatoren PAA ‐ g ‐ Fe2S2 mit biomimetischen {Fe2S2} ‐ Zentren wurden hergestellt. Zusammen mit CdSe ‐ Quantenpunkten (CdSe ‐ QDs) und Ascorbinsäure zeigen sie außergewöhnliche Turnoverzahlen (TON) und ‐ frequenzen (TOF) von 27 135 bzw. 3.6 s−1 für die photokatalytische Bildung von H2 in Wasser; dies ist die bisher höchste Effizienz für [FeFe] ‐ Hydrogenasemimetika. [ABSTRACT FROM AUTHOR]