Patent ID: 8617421

Claim:
A method for marking an object with a metal-organic complex, comprising: (a) providing a composition comprised of (A) a metal-organic framework comprised of complexes between two or more different lanthanides and an organic ligand, wherein said lanthanides are present in a predetermined ratio, wherein said ligand has multiple metal-binding sites and an electronic structure that accommodates a transfer of energy to said lanthanides, and wherein said complex, upon the transfer of energy to said lanthanides, emits electromagnetic radiation having emission maxima of at least 640 nm, and (B) at least one component selected from the group consisting of an adhesive and a binder, wherein said ligand is (4,4â€²-[(2,5-dimethoxy-1,4-phenylene)di-2,1-ethenediyl]bis-carboxylate); and then (b) applying said composition to said object.