Fig. 2: Absorption spectra (offset) of the same mixture in different solvents.

a The four solvents are 3.0 mL of BTA and water mixtures, with 0.5 (gray trace), 1.0 (green trace), 1.5 (blue trace), and 2.0 (magenta trace) mL BTA. b The three solvents are the mixtures of 1.5 mL primary amines (BTA (blue trace), PrA (lighter blue trace), and ETA (lightest blue trace)) and 1.5 mL water. All the spectra are collected from the solutions kept in cuvettes at room temperature for 24 h. The dashed lines signify the positions indicated. Evidently, increasing the amount of BTA, or using a primary amine with a shorter alkyl chain, facilitates the production of MSC-360.