Unravelling the true MOF-5 luminescence

Abstract

This study provides a rigorous analysis of MOF-5 fluorescence, unifying previously dissimilar results. Pure MOF-5 fluorescence was identified as only ligand centered and the rise of other mode of emission were observed when exposed to humidity.

Strongly Bound Excitons in Metal–Organic Framework MOF-5: A Many-Body Perturbation Theory Study

“…24,43 The optical absorption is dominated by ligand-centered transitions at least up to ∼ 6 eV, also in agreement with inferences drawn in recent experimental studies. 16,20 The large dierence between the fundamental gap and optical band gap points to strongly bound excitons in the studied spectral region with binding energies of several eVs, previously not discussed in literature.…”

“…At first, it was identified as a semiconductor with an optical band gap of 3.4–3.7 eV featuring a ligand-to-metal charge transfer excitation. ,, Later, by using the photoluminescence spectra of MOF-5 for assessment of its purity, it was shown that the method of synthesis used by early studies leads to the presence of ZnO impurities within the framework, and these impurities can exhibit the observed semiconducting behavior . Subsequent experimental studies also showed that the photoluminescence and absorption spectra of MOF-5 are very sensitive to the presence of water and structural damage, ,, further raising questions on the early works. The studies that followed showed that the onset of the optical absorption of possibly impurity-free MOF-5 is located at ∼3.8–4.1 eV. ,− In parallel, several computational works − have established a semiconducting behavior of this MOF, and closely related ones, , upon a computed band gap of around 3.6 eV using Kohn–Sham density functional theory (DFT) with semilocal Perdew–Burke–Ernzerhof (PBE) parametrization of exchange correlation (XC).…”

Strongly Bound Excitons in Metal-Organic Framework MOF-5: A Many-Body Perturbation Theory Study

“…24,43 The optical absorption is dominated by ligand-centered transitions at least up to ∼ 6 eV, also in agreement with inferences drawn in recent experimental studies. 16,20 The large dierence between the fundamental gap and optical band gap points to strongly bound excitons in the studied spectral region with binding energies of several eVs, previously not discussed in literature.…”

Highly efficient functionalized MOF-LIC-1 for extraction of U(vi) and Th(iv) from aqueous solution: experimental and theoretical studies

“…For example, chemical stability is crucial for applications in aqueous media and/or at different pHs. 17 MOFs suffer from being unstable/sensitive towards moisture 18,19 and high acidity. Therefore, it is important to synthesise MOFs possessing high stability, large surface area and high porosity to obtain desirable applications.…”