Preparation and magnetic properties of Mn-doped porous carbon nitride sheets

We report a simple method to fabricate Mn-doped poly(triazine imide) (PTI) by using melamine and cyanuric chloride as the building blocks, and Mn as the coupling agent. This material forms a two-dimensional imide-bridged triazine (C6N9H3) network, with an ordered arrangement of 24-atom voids. The synthesized PTI exhibits a large magnetization due to the localized d-electrons of Mn2+ ions, which suggests that PTI contains a large number of Mn2+ ions in the 24-atom voids. In addition, on being treated with HNO3, PTI absorbs NO3- ions in the 24-atom voids, which replace the Mn2+ ions present there, and forms a structurally well-ordered hostguest conjugated sheet, PTI center dot NO3. X-ray diffraction measurements of PTI center dot NO3 indicate that it crystallizes in the hexagonal space group P6(3)cm, with lattice parameters a = 8.43 angstrom and c = 6.52 angstrom. The remaining Mn2+ ions are intercalated within the interlayer 24-atom void center sites to maintain charge balance, and constitute an Mn-NO3 column along the c-axis. The Mn2+ -intercalated PTI center dot NO3 structure exhibits Curie paramagnetism, with a negative Weiss temperature. The present study reports the bulk synthesis of a well-characterized, crystalline, graphitic carbon nitride containing magnetic transition metal (TM) ions, that has potential applications in carbon-based magnetic materials and catalysis.