Exploring\nthe Photophysical and Mechanical Behavior\nof Fluorescent Metal–Organic Framework Monoliths

Luminescent metal–organic frameworks exhibit great\npotential\nas materials for nanophotonic applications because of their programmable\nproperties and tunable structures. In particular, luminescent guests\n(LG) can be hosted by metal–organic frameworks due to their\nporosity and guest confinement capacity, forming LG@MOF composite\nsystems. However, such guest–host systems are mainly produced\nas loose powders, preventing their widespread use in practical devices\nand technological applications that require implementation of a stable\ncontinuum solid. In this regard, using monolithic MOF hosts might\nbe a workable option to solve this challenge. Herein, we reported\nthe facile synthesis and fabrication of novel prototypical sol–gel\nmonolithic systems, designated as LG@monoMOF. Red (rhodamine B), blue\n(7-methoxycoumarin), and yellow (fluorescein) emitting dyes were encapsulated\nin a robust UiO-66 monolithic host, resulting in the red, blue, and\nyellow light-emitting luminescent monoliths. The mechanical and photophysical\ncharacterization of the three LG@monoMOF systems was systematically\ncarried out in order to unravel the role of guest–host interactions\nin the mechanical and optical response of the bespoke LG@monoMOF composites.