*3.6. Thermal Analysis*

To determine the thermal stability of cocrystals, thermogravimetric analysis (TGA) was performed under a stream of air in the range 25–300 ◦C. Considering that the compounds are thermally stable until a 10% weight loss of the sample occurs, it can be seen that (**1**) is stable up to 179 ◦C, very similar to mandelic acid, while (**3**) undergoes a 10% weight loss when 209 ◦C is reached, so that its stability is comparable to that of isonicotinamide (Figure 13). Above these temperatures a slow weight loss is observed up to 300 ◦C, decomposing and releasing CO, CO2 and various nitrogen oxides, not resulting in final solid waste. The phase purity of the as-synthesized samples could be confirmed by the PXRD pattern, where the characteristic peaks match well with those of the simulated PXRD pattern based on the single crystal data (Figure S10).

**Figure 13.** TG thermograms of pure components and the cocrystals **1** (**left**) and **3** (**right**).
