Carboxylated WS2 INTs

The carboxylated INTs were prepared using the conditions in Table 1. Details for Sample 1 are presented as a representative example.


**Table 1.** Sample parameters for the carboxylation reaction.

To a solution of 2-bromoacetic acid (0.80 g, 5.76 mmol) in DMF (2 mL) was added AgOAc (20 mg, 0.12 mmol) and WS2 INTs (200 mg). The mixture was heated in an oil bath to 80 °C and stirred for 18 h. After cooling to room temperature, the mixture was centrifuged and the supernatant discarded. The solids were washed with ethanol followed by centrifugation (11,000 rpm 5 min) 5 times and dried under vacuum to obtain carboxylated WS2 INTs containing 0.150 mmol carboxylic acid per gram of INT.

Quantification of the carboxylic acid was done indirectly by coupling 1,3-diaminopropane to the carboxylic acid using EDC as a coupling agent, followed by the Kaiser test for terminal amines [10,13].
