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Free keywords:
Basic solid material; Carbon dioxide fixation; CN; Heterogeneous catalysis; Noble carbons
Abstract:
Herein, we study the basic nature of noble covalent, sp2-conjugated materials prepared via direct condensation of guanine in the presence of an inorganic salt melt as structure directing agent. At temperatures below 700 °C stable and more basic addition products with at C:N ratio of 1 (C<sub>1</sub>N<sub>1<sub> adducts) and with rather uniform micropore sizes are formed. Carbonization at higher temperatures breaks the structural motif, and N-doped carbons with 11 wt% and surface areas of 1900 m<sup2</sup> g<sup>-1</sup> are obtained. The capability for CO<sub>2</sub> sorption and catalytic activity of the materials depend of both their basicity and their pore morphology. The optimization of the synthetic parameters lead to very active (100% conversion) and highly selective (99% selectivity) heterogeneous base catalysts, as exemplified with the model Knoevenagel condensation of benzaldehyde with malononitrile. The high stability upon oxidation of these covalent materials and their basicity open new perspectives in heterogeneous organocatalysis.
