Artificial Photosynthesis/Biosynthesis

Fully sp2-carbon conjugated two-dimensional covalent organic frameworks as artificial photosystem I with unprecedented efficiency

    The synthesis of fully sp2-carbon conjugated covalent organic framework (COF) is extremely challenging given the difficulty of “irreversible” carbon-carbon double bond (-C=C-) formation. Here, we report the successful preparation of a 2D COF (TP-COF) based on triazine as central planar units bridged by sp2-carbon linkers through the -C=C- condensation reaction. High-resolutiontransmission electron microscopy (HRTEM) clearly confirmed the tessellated hexagonal pore structure with a pore center-to-center distance of 2 nm. Powder X-ray diffraction (PXRD) together with structural simulation revealed an AA stacking mode of the obtained layered structure. The TP-COF turned out to be an excellent semiconductor material bearing a LUMO of -3.23 eV and a band gap of 2.36 eV. Excitingly, this novel sp2-carbon conjugated TP-COF exhibited unprecedented coenzyme regeneration efficiency, and can significantly boost the coenzyme assisted synthesis of L-glutamate to a record-breaking 97% yields within 12 minutes.