Dye-loaded metal organic frameworks (MOFs) are regarded as one of the most fascinating luminescent materials for selective chemical sensing. Herein, a facile two-step synthesis procedure is reported for the successful encapsulation of fluorescein dye into porous zinc–adenine metal–organic framework (bio-MOF-1) crystals, and thus the aggregation-caused quenching of dye molecules can be eliminated in the confined MOF structure to further create dual emission centers. The as-prepared solid state fluorescein@bio-MOF-1 composite exhibits both the characteristic emissions of the fluorescein dye and bio-MOF-1, and host–guest energy transfer also occurs. Particularly, depending on the variety of the luminescence intensities of different metal ions incorporated in fluorescein@bio-MOF-1, such a host–guest system could be used for high-sensitive sensing of metal cations, especially for the drastic luminescence quenching of Fe3+ ions. The quenching effect coefficient (Ksv) for every metal ion detected is calculated, and the largest Ksv value for Fe3+ ions is determined to be 5072 M−1. Such an encapsulation strategy can be widely adopted to design new dye@MOF composites with multiple luminescent centers for metal cation sensing.
Luminescent metal–organic frameworks (MOFs) (typically dye-encapsulated MOFs) are considered as one kind of interesting downconversion materials for white-light-emitting diodes (LEDs), but their quantum efficiency (QE) is not sufficient and thus needs to be significantly enhanced for practical applications. In this study, we successfully synthesized a series of Rh@bio-MOF-1 (Rh = rhodamine) with an internal QE as high as ∼79% via a solvothermal reaction followed by cation exchanges. The high efficiency of the Rh@bio-MOF-1 composites was attributable to the high intrinsic luminescent efficiency of the selected Rh dyes, the confinement effect in the bio-MOF-1 host, and the uniform particle morphology. The emission maximum could be continuously tuned from 550 to 610 nm by controlling the species and concentration of encapsulated dye molecules, showing great color tunability of the dye-encapsulated MOFs. The emission lifetime of ∼7 ns was 1 or 2 magnitude orders shorter than that of Ce3+- or Eu2+-doped inorganic phosphors, allowing for visible light communication (VLC). White LEDs, fabricated by using the synthesized Rh@bio-MOF-1 composite and inorganic phosphors of green (Ba,Sr)2SiO4:Eu2+ and red CaAlSiN3:Eu2+, exhibited a high color rendering index of 80–94, a luminous efficacy of 94–156 lm/W, and an excellent stability in color point against drive current. The Rh@bio-MOF-1 composites with tunable colors, short emission lifetime, and high QE are expected to be used for smart white LEDs with multifunctions of both lighting and VLC.
A novel kind of amphiphilic hyperbranched polymer (AHP), poly(2-(dimethylamino)ethyl methacrylate)-co-polystyrene (HPTAM-co-PS), was synthesized via the combination of reversible addition–fragmentation chain-transfer polymerization and self-condensing vinyl polymerization (RAFT-SCVP). HPTAM-co-PS was functionalized via the highly efficient Menschutkin click reaction, resulting in hyperbranched poly(propargyl quaternary ammonium methacrylate)-co-polystyrene (HPPrAM-co-PS) with a hydrophilic quaternary ammonium salt core and hydrophobic PS shell. The average numbers of dye molecules trapped by each molecule of HPPrAM-co-PS (24.2 kDa) were 24.1 for methyl orange (MO), 22.0 for fluorescein sodium (FS), 24.2 for rose bengal (RB), and 238.4 for Congo red (CR). The polymer–dye complexes show excellent colouring effects for both PS and poly(styrene-b-butadiene-b-styrene) (SBS) membranes; the colour of the membrane containing AHP is very stable and uniform. Our work opens an avenue for the design of efficient dye-colouring additives and for the application of hyperbranched polymers in the field of polymer colouring.
危险品化学品经营许可证（带存储）