Highly luminescent scintillating hetero-ligand MOF nanocrystals with engineered Stokes shift for photonic applications

Abstract

Large Stokes shift fast emitters show a negligible reabsorption of their luminescence, a feature highly desirable for several applications such as fluorescence imaging, solar-light managing, and fabricating sensitive scintillating detectors for medical imaging and high-rate high-energy physics experiments. Here we obtain high efficiency luminescence with significant Stokes shift by exploiting fluorescent conjugated acene building blocks arranged in nanocrystals. Two ligands of equal molecular length and connectivity, yet complementary electronic properties, are co-assembled by zirconium oxy-hydroxy clusters, generating crystalline hetero-ligand metal-organic framework (MOF) nanocrystals. The diffusion of singlet excitons within the MOF and the matching of ligands absorption and emission properties enables an ultrafast activation of the low energy emission in the 100 ps time scale. The hybrid nanocrystals show a fluorescence quantum efficiency of ~60% and a Stokes shift as large as 750 meV (~6000 cm−1), which suppresses the emission reabsorption also in bulk devices. The fabricated prototypal nanocomposite fast scintillator shows benchmark performances which compete with those of some inorganic and organic commercial systems.

Tunable Competitive Absorption-Induced Signal-On Photoelectrochemical Immunoassay for Cardiac Troponin I Based on Z-Scheme Metal–Organic Framework Heterojunctions

“…The photoluminescence properties of MOFs are reported to be closely related to their corresponding ligands. , The fluorescence excitation spectrum of the ligand (H 2 Bpdc) in Zr-MOF (broad band centered at 200–380 nm; Figure S4) was similar to the fluorescence spectrum of Zr-MOF (Figure S5). The normalized UV–vis absorption and fluorescence excitation spectra of Cu­(II) ions and Zr-MOF revealed an overlap in the wavelength range between 200 and 340 nm (Figure d).…”

Efficient radioactive gas detection by porous metal-organic framework scintillating nanocrystals.

“…Hf-based MOF nanocrystals comprising luminescent DPA ligands (Hf-DPA) were obtained by solvothermal syntheses modulated by the relative amount of formic acid that regulates their crystal size (Methods and Figure S4-S7). 23,24 The synthesis was optimized to produce octahedral nanocrystals with 385 nm diameter (Figure 2A) in highly reproducible batches of ~ 200 mg (Supplementary Figures S8-S11). The structure was solved by Rietveld refinement combined with PW-DFT of synchrotron-source PXRD pattern collected at 298/293 K (Figure S15-S17).…”

“…[18][19][20] Moreover, highly luminescent conjugated chromophores, included as ligands or luminescent guests, produce emissive materials with unique photophysical [21][22][23][24] and scintillating properties. [22][23][24] Nevertheless, despite the increasing number of reports about the development of MOFs as effective scintillators, to date, their potential application as scintillating materials for the detection of radioactive gases has not yet been reported. The only examples in literature describe the general luminescence properties of MOFs being sensitive to the presence of specific radioactive heavy-metal ions, 25 or to the use of MOFs as sorbents for the removal of radionuclides.…”

“…The controlled self-assembly of inorganic nodes and organic ligands produces tailored framework architectures with a specific topology and well-defined porosity for gas capture, selective adsorption and separation, and storage. [18][19][20] Moreover, highly luminescent conjugated chromophores, included as ligands or luminescent guests, produce emissive materials with unique photophysical [21][22][23][24] and scintillating properties. [22][23][24] Nevertheless, despite the increasing number of reports about the development of MOFs as effective scintillators, to date, their potential application as scintillating materials for the detection of radioactive gases has not yet been reported.…”

Novel lanthanide nanoparticle frameworks for highly efficient photoluminescence and hypersensitive detection

“…10–12 Most of the reported luminescent MOFs that contain MC nodes emit light from their organic ligands based on the charge transfer between the precious metal clusters and the organic ligands. 3,4,13,14 The photoluminescence mechanisms are often very complicated and even distinct from each of such MOFs, 3,4,13,14 which imparts tremendous difficulty in rationally designing the suprastructure of LnCs with unambiguous photoluminescent properties.…”