NanoMOF‐Based Multilevel Anti‐Counterfeiting by a Combination of Visible and Invisible Photoluminescence and Conductivity

Abstract This study presents nanosized metal‐organic framwork (nanoMOF)‐based multifunctional mixed‐matrix‐membranes (MMMs) and composite powders as extremely sensitive responder materials for a responder‐stimulus based multilevel anti‐counterfeiting. The physicochemical properties of nanoMOF‐based composites offer a wide operational range as anti‐counterfeiting tags. Nine responder materials are presented, constituted of trivalent lanthanide‐containing nanoMOFs ([Ln 3 (bdc) 4.5 (H 2 O) 3 (dmf) 2 ] (nLn‐bdc); bdc 2− ═benzene‐1,4‐dicarboxylate; Ln═Eu, Tb, Yb) and polystyrene sulfonate, pyrolyzed resorcinol‐formaldehyde and polysulfone as matrices. These materials inherit distinct properties, and their combination provides visible and near‐infrared light emission and specific conductivity for multiple security level anti‐counterfeiting. The additive and interdependent nature of security features in the developed anti‐counterfeiting materials ensures that altering one feature will invariably affect others, thereby reinforcing the overall integrity and resilience of the security mechanism. Even the pitch‐black composites of nLn‐bdc and pyrolyzed resorcinol‐formaldehyde show bright light emission to the near‐infrared range, when stimulated by UV‐light being suitable for black materials. This work also describes a matrix‐based active contribution as security feature to an anti‐counterfeiting tag, instead of being solely used as a carrier for the security feature‐bearing nanoMOFs. The combination of multiple levels of security by different properties marks these multifunctional composites as anti‐counterfeiting materials being complicated to copy including a proof‐of‐principle experiment.