Structure and reactivity of 2,4,6-tricyano-1,3,5-triazine under high-pressure conditions

Abstract

2,4,6-Tricyano-1,3,5-triazine is an attractive precursor for the synthesis of extended layered and nanoporous carbon nitrides. Using high pressure can achieve this via one-step condensation reactions. As a first step towards this goal we have characterized the structural properties and stability P–T range of the monomer (phase I) using synchrotron X-ray diffraction combined with FTIR spectroscopy under combined high pressure and high temperature conditions in a resistively heated diamond anvil cell. A new high pressure structure (phase II) appeared following compression to above 2.4 GPa at ambient temperature. The structure was identified as orthorhombic belonging to space group P2₁2₁2₁. The pressure–temperature conditions of the I–II phase boundary, as well as the melting line have been established. The chemical transformation of the phase II crystal was studied between 4 and 10 GPa at temperatures ranging from 550 to 300 K. X-ray and spectroscopic examination of the reaction products revealed a crystalline phase that could be assigned to a layered carbon nitride containing linked s-triazine rings along with amorphous material. Analysis of the kinetics indicates that the structural transformation is driven by defect formation.