Recently,
photobiocatalysis with oxidoreductases, inspired by natural
photosynthesis, has drawn increasing attention due to its high catalytic
efficiency and selectivity. However, although an important cofactor
for the activation of redox enzymes, nicotinamide adenine dinucleotide
(NADH) suffers from the drawbacks of cost and limited stability. Moreover,
the design of an effective NADH regeneration system remains a huge
challenge. Here, we report a visible light-driven conjugated microporous
polymer DBTS-CMP1 for the heterogeneous photocatalytic regeneration
of NADH. Thanks to various improved properties, such as extended visible
light absorption, adequate fluorescence lifetime, enhanced wettability,
and rapid charge separation and transfer, an NADH regeneration efficiency
of 84% in 45 min was achieved with DBTS-CMP1. In addition, the small
molecule model compound DBTS-Ph2, which shares similar structural
motifs, was also designed to further study the photoinduced electron
transfer process. The strong coordination interaction between dibenzo-[b,d]thiophene
sulfone and the Rh metal center, as reflected in fluorescence quenching,
cyclic voltammetry, and Fourier-transform infrared spectroscopy measurements,
plays an essential role in electron transfer from the photocatalyst
to the Rh complex, thus endowing DBTS-CMP1 with a high reaction conversion
and selectivity (100%) for 1,4-NADH regeneration. Finally, a photobiocatalytic
system was constructed by incorporating NADH-dependent alcohol dehydrogenase
for the reduction of formaldehyde into methanol. A total amount of
2.23 mM methanol with a turnover number of 2.23 mmol g–1 was obtained after 95 min in the photobiocatalytic system, indicating
the high photostability and biocompatibility of our DBTS-CMP1 photocatalyst.
A novel series of carboxybetaine surfactants were synthesized for the first time and their physicochemical properties were systematically investigated.
Photocatalyst–biocatalyst
coupled systems offer a sustainable
approach for converting CO2 into high-value compounds.
However, the usually excessive use of organic sacrificial electron
donors often leads to undesired side products and toxic intermediates.
Here, we report a complete artificial photosynthesis system for selective
CO2 reduction into formate with simultaneous H2O2 formation using water as the electron donor. The photocatalyst
consists of polymeric carbon nitride with implanted single cobalt
atoms as oxidative sites, while formate dehydrogenase from Candida boidinii was employed as reductive sites via a coupled
redox cycle of nicotinamide adenine dinucleotide as cofactor. The
artificial photosynthesis system demonstrates a competitive catalytic
formate production rate of 420 μmol gcat.
–1 h–1. DFT calculations reveal that the presence
of single cobalt atoms can significantly accelerate the water oxidation
into H2O2. The result demonstrates a benchmark
example of a polymeric artificial photosynthesis system with remarkable
photostability and catalytic selectivity for high-value compound production
directly from CO2 without using extra organic electron
donors.
A novel series of sulfobetaine surfactants, 3-((4-(alkoxy)-3,5-dimethylbenzyl) dimethylammonio)-2-hydroxypropane-1-sulfonate (C n OBSb, n = 12, 14, and 16), were synthesized for the first time. The chemical structures of products were characterized by high-resolution mass spectra, 1 H NMR, and 13 C NMR spectrometry. The physicochemical properties of C n OBSb were studied by thermogravimetric analysis, equilibrium surface tension measurement, steady-state fluorescence, dynamic light scattering (DLS), and cryogenic transmission electron microscopy (cryo-TEM). The results demonstrated that surface tension values of C n OBSb are in the range of 28.32−30.14 mN/m at a fairly low critical micelle concentration (cmc).The adsorption and micellization properties of C n OBSb were dependent on the hydrocarbon chain length and presence of phenyl group. The results of DLS and cryo-TEM measurements revealed that C n OBSb molecules spontaneously formed vesicles in aqueous solution above the cmc. Furthermore, the application properties indicated that C n OBSb possessed superior interfacial tension capability, outstanding wetting ability, and good foaming and emulsifying properties.
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