Synthesis and Twin Polymerization of Si(OCH₂py)₄ for Nitrogen-containing Carbon Materials

The synthesis and twin polymerization (TP) of Si(OCH₂py)₄ (3a, py=2-^cC₅H₄N; 3b, py=3-^cC₅H₄N; 3c, py=4-^cC₅H₄N) is discussed. The solid state structures of 3b, c were confirmed by single-crystal X-ray crystallography showing non-conventional H-bonding, forming 2D chains (3b) or 3D networks (3c). Thermally induced TP of 3a–c and their simultaneous polymerization with 2,2‘-spiro-bi[4H-1,3,2-benzodioxasiline] (4) is described. The resulting hybrid materials were characterized by ¹H, ¹³C{¹H}, and ²⁹Si{¹H} CP MAS NMR spectroscopy confirming the transformation of the SiOCH₂ moieties into CH₂ groups enabling the formation of the respective polymers. These results were supported by HAADF-STEM studies, displaying micro-structuring. Nitrogen-containing porous carbon materials C_1–C_3 show surface areas of 1300 and 1700 m²g^-1, large pore volumes between 0.6–1.2 cm³g^-1, and nitrogen contents of up to 3.1 at-%. X-ray photoemission spectroscopy reveal that pyrrolic, pyridine, and pyridone nitrogen atoms are present. If equimolar amounts of 3a–c and 4 are simultaneously polymerized in the presence of [Pd(OAc)₂] (5), then the Pd nanoparticle-decorated material Pd@C_3 (900 m²g^-1) was obtained, which showed k values of -0.083 and -0.066 min^-1 in the reduction of methylene blue and methyl orange, proving the accessibility of the Pd NPs.