title: Tunable solid-state fluorescent materials for supramolecular encryption.
abstract: Tunable solid-state fluorescent materials are ideal for applications in security printing technologies. A document possesses a high level of security if its encrypted information can be authenticated without being decoded, while also being resistant to counterfeiting. Herein, we describe a heterorotaxane with tunable solid-state fluorescent emissions enabled through reversible manipulation of its aggregation by supramolecular encapsulation. The dynamic nature of this fluorescent material is based on a complex set of equilibria, whose fluorescence output depends non-linearly on the chemical inputs and the composition of the paper. By applying this system in fluorescent security inks, the information encoded in polychromic images can be protected in such a way that it is close to impossible to reverse engineer, as well as being easy to verify. This system constitutes a unique application of responsive complex equilibria in the form of a cryptographic algorithm that protects valuable information printed using tunable solid-state fluorescent materials.
authors.affiliation: Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA.
authors.forename: Xisen
authors.initials: X
authors.lastname: Hou
authors.affiliation: Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA.
authors.forename: Chenfeng
authors.initials: C
authors.lastname: Ke
authors.affiliation: Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA.
authors.forename: Carson J
authors.initials: CJ
authors.lastname: Bruns
authors.affiliation: Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA.
authors.forename: Paul R
authors.initials: PR
authors.lastname: McGonigal
authors.affiliation: Cycladex, c/o Innovation and New Ventures Office, Northwestern University, 1800 Sherman Avenue, Suite 504, Evanston, Illinois 60201-3789, USA.
authors.forename: Roger B
authors.initials: RB
authors.lastname: Pettman
authors.affiliation: Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA.
authors.forename: J Fraser
authors.initials: JF
authors.lastname: Stoddart