Investigating halogen bonds in substituted graphitic carbon nitride through vibrational spectroscopy

The graphitic carbon nitride (g-C₃N₄) triazine backbone was substituted with OH, SH, and PH₂ substituents to examine its potential for halogen bonding applications. A series of four halogen bond (XB) donors were systematically complexed with substituted triazine units in a series of 1 : 1, 2 : 1, and 3 : 1 XB donor : acceptor complexes for comparison studies. These XB acceptor units offered stabilizing hydrogen bonding sites in addition to the halogen bonding sites, depending upon the position the XB donor bonded to the acceptor. The addition of one XB donor to each acceptor in the 1 : 1 and 2 : 1 XB complexes was shown to have ≥90% additivity to the binding energies. Local mode analysis was performed for further comparison of the halogen and hydrogen bonds formed, concluding that these interactions are XB dominated with supportive hydrogen bond interactions.