A solvent-controlled photoresponsive ionic hydrogen-bonded organic framework for encryption applications.

Two novel ionic hydrogen-bonded organic frameworks (iHOF-17 and iHOF-18) were obtained by integrating organosulfonic acids with amidine salts. Among them, iHOF-18 exhibits fast, reversible, and high-contrast UV-induced photochromic properties, and this property is solvent-controlled. This work provides valuable insights for designing advanced anti-counterfeiting techniques and encryption applications.