Fluorescent Dye-Based Metal–Organic Framework Piezochromic and Multicolor-Emitting Two-Dimensional Materials for Light-Emitting Devices

Abstract

The dye encapsulated metal–organic frameworks (MOFs) are of interest for their practical applications such as light-emitting diodes, temperature sensing, and microlasers. However, very few MOFs have been reported to date where the dye moiety is utilized as one of the components of the framework. Fluorescein dye (FSD) doped materials have an ability to emit various colors such as red, green, and yellow depending upon their tautomeric form and external stimuli. In anticipation of light-emitting devices, three FSD-based novel MOFs, namely, {[Co2(FSD)2(H2O)4]·H2O·MeOH} n , FSDCo; {[Mn2(FSD)2(H2O)4]·H2O·MeOH} n , FSDMn; and {[Cd2(FSD)2(H2O)3(MeOH)]·2­(H2O)} n , FSDCd, have been designed and synthesized. These crystalline materials were shown to exhibit multicolor light-emitting behavior and reversible green to brown piezochromism, implying their potential to act as fluorescent switches, mechanosensors, and security papers. Further, these crystalline MOFs were also shown to exhibit a rare optical phenomenon called pleochroism. The green colored crystals displayed multiple colors under polarized light due to the agglomeration of nano- and microcrystals at different angles on the surface of macrocrystals.

Recent advances in process engineering and upcoming applications of metal–organic frameworks

“…(i) Confocal microscopic images and merged images of the single crystals of FSDCd at different excitation wavelengths. Reprinted with permission from [429] . Copyright 2019 American Chemical Society.…”

“…Similarly, Maity et al developed three MOF composites with encapsulated fluorescein dye (FSD): [Co 2 (FSD) 2 (H 2 O) 4 ]·H 2 O·MeOH, [Mn 2 (FSD) 2 (H 2 O) 4 ]·H 2 O·MeOH, and [Cd 2 (FSD) 2 (H 2 O) 3 (MeOH)]·2(H 2 O), denoted as FSDCo, FSDMn, and FSDCd, respectively [429] . The prepared MOF composites showed multi-color light emissions under unpolarized and polarized light.…”

A New Era of Metal–Organic Framework Nanomaterials and Applications

“…25 Furthermore, fluorescent dye-encapsulated MOFs were shown to exhibit multicolor light-emitting phenomena and reversible piezochromism. 26…”

A Reusable Efficient Green Catalyst of 2D Cu-MOF for the Click and Knoevenagel Reaction

“…Metal-organic frameworks (MOFs) are burgeoning targets for their potential applications in gas separation and storage [ 1 , 2 , 3 ], energy research [ 4 , 5 , 6 , 7 , 8 , 9 , 10 ], sensing of ions and molecules [ 11 , 12 , 13 ], bio-imaging [ 14 ], drug delivery [ 15 , 16 ], reusable and recycling sustainable catalyses [ 17 , 18 ], magnetism [ 19 , 20 ], etc. In the last few decades, such materials have received more attention towards development of more flexible catalytic materials owing to their varying symmetric and large pore volume, high surface area, tunable pore size and versatile functionality together with the diversity of metal knots and their redox states, functional groups, and the retention of crystallinity after catalytic reactions.…”