Dual-Guest Functionalised ZIF-8 Framework for 3D Printing White Light-Emitting Composites

Abstract: Metal-organic frameworks (MOFs) stand as a promising chemically-active host scaffold for the encapsulation of functional guests, because they could enhance luminescent properties by molecular separation of fluorophores in the nanoscale pores of the MOF crystals. Herein, we show simultaneous nanoconfinement of two fluorophores viz. (A) Fluorescein and (B) Rhodamine B in the sodalite cages of ZIF-8, constructed under ambient conditions through a simple one-pot reaction. We report a novel dual-guest@MOF system, termed: A+B@ZIF-8, which overcomes the intrinsic problem of aggregation caused quenching in the solid-state to gain bright yellow emission under UV irradiation. Subsequently, we combine this yellow emitter with a blue-emitting photopolymer resin, to yield a 3D printable luminescent composite material. We design a number of 3D printable composite objects for converting UV into warm white light emission, achieving a high quantum yield of ~44% in the solid-state 3D printed form. This research instigates the bespoke application of a vast range of 3D printable Guest@MOF designer composites targeting energy-saving lighting devices, smart sensors and future optoelectronics.