Details

Autor(en) / Beteiligte

• González Chávez, Fernando
• Nájera, Hugo
• Leyva, Marco Antonio
• Solorza-Feria, Omar
• González, Federico
• Beltrán, Hiram Isaac

Titel

New 2D Lanthanide MOFs Constructed from Bis(imide) Pyromellitic Alanine Ligands with Enhanced Fluorescence toward Activation and Modulation of Microstructure

Ist Teil von

• Crystal growth & design, 2020-07, Vol.20 (7), p.4273-4292

Ort / Verlag

American Chemical Society

Erscheinungsjahr

2020

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Five isostructural 2D lanthanide (Ln) MOFs were synthesized using 2,2′-(1,3,5,7-tetraoxo-5,7-dihydropyrrolo­[3,4-f]­isoindole-2,6­(1H,3H)-diyl)­dipropionic acid (PBIA ligand) semiflexible ligand and Pr/Eu/Tb/Er/Tm hydrated nitrates in DMF leading to PBIA–Pr/PBIA–Eu/PBIA–Tb/PBIA–Er/PBIA–Tm materials. New MOFs were characterized employing Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), single crystal and powder X-ray diffractions (SCXRD/PXRD), photoluminescence, and scanning electron microscopy (SEM). MOFs crystallized in P1̅ triclinic space group, developing 2D structures through different ligand coordination-conformation schemes toward dinuclear Ln–metal clusters (SBU). Materials were thermally stable ca. 400 °C, being activated partially removing DMF → Ln molecules giving PBIA–Pr ACT /PBIA–Eu ACT /PBIA–Tb ACT /PBIA–Er ACT /PBIA–Tm ACT phases reorganizing the PBIA ligand toward isobidentate mode, releasing ca. two of six-coordinated DMF per SBU. Just Eu/Tb materials could be studied in the 200–800 nm range showing characteristic emission bands, and the PBIA ligand was not sensitization-suitable for other Ln emissions. Band shape modification and emission intensity enhancement of 6.7­(Eu) and 30.6­(Tb) resulted in Eu/Tb-activated compounds. Excitation of PBIA–Eu/PBIA–Eu ACT directly in Eu3+ resulted efficient, but not via the PBIA ligand. In PBIA–Tb/PBIA–Tb ACT compounds, PBIA ligand excitation is more efficient and PBIA–Tb ACT could be directly excited in Tb3+. Hence nonradiative processes are playing decisive roles in luminescent properties. Isostructural materials resulted, but different Ln-metals provided different morphologies/sizes, modulating microstructures, and luminescence properties. These materials would be candidates for molecular/ionic sensing, through emission modulation, mainly when Eu and Tb are employed as Ln.