A diazonium salt-based ionic liquid for solvent-free modification of carbon

A novel ionic liquid that consists of p-butylbenzenediazonium ions and bis(trifluoromethanesulfonyl)amidates (Tf₂N^-) has been synthesized as a task-specific ionic liquid for the solvent-free modification of carbon materials. The use of anions Tf₂N^- is the key to rendering the hydrophobicity, low liquidus temperature, and ionicity to this novel molten salt. This diazonium salt has a melting point of 7.2°C and a moderate electric conductivity of 527 μs/cm at 25°C. The thermal stability of this diazonium ionic liquid has been investigated by high-resolution thermogravimetric analysis (HRTGA). The compound is stable up to about 90°C in nitrogen, which is only 10°C less than its solid tetrafluoroborate counterpart. The modification of carbon materials has been carried out through both thermal and electrochemical activations of diazonium ions to generate free radical intermediates without the use of any solvent. The surface-coverage loadings of 3.38 μmol/m² and 6.07 μmol/m ² for covalently attached organic functionalities have been achieved by the thermally induced functionalization and electrochemically assisted reaction, respectively.