Mixed cluster heterometallic metal-organic frameworks for complex optical tags

Abstract

A rapid and facile design strategy to create a highly complex optical tag with programmable, multimodal photoluminescent properties is described. This is achieved via intrinsic and biomolecule-fluorophore hidden signatures. As a first covert feature of the tag, an intricate novel heterometallic near-infrared (NIR) emitting mesoporous metal-organic framework (MOF) was synthesized comprising homometallic hexanuclear clusters based on Nd and Yb. To generate controlled, multimodal, and tailorable emission with difficult to counterfeit features, the NIR emissive MOF was post-synthetically modified via a fluorescent biomolecule labeling design strategy. The surface attachment of several distinct fluorophores, including the simultaneous attachment of up to three distinct fluorescently labeled DNA oligos was demonstrated, with excitation and emission properties across the visible spectrum (480-800 nm). The DNA inclusion as a secondary covert element in the tag was demonstrated via detection of SYBR Gold dye association.