AUTHOR=Celis-Arias Vanessa , Garduño-Wilchis Ismael A. , Alarcón Gilberto , González Chávez Fernando , Garrido Guerrero Efrain , Beltrán Hiram I. , Loera-Serna Sandra 

TITLE=Room-temperature synthesis of nanometric and luminescent silver-MOFs

JOURNAL=Frontiers in Chemistry

VOLUME=10

YEAR=2023

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2022.1065622

DOI=10.3389/fchem.2022.1065622

ISSN=2296-2646

ABSTRACT=<p>Three silver-MOFs were prepared using an optimized, room-temperature methodology starting from AgNO₃ and dicarboxylate ligands in water/ethanol yielding <bold>Ag</bold><sub><bold>2</bold></sub><bold>BDC</bold>, <bold>Ag</bold><sub><bold>2</bold></sub><bold>NDC</bold> (<bold>UAM-1</bold>), and <bold>Ag</bold><sub><bold>2</bold></sub><bold>TDC</bold> (<bold>UAM-2</bold>) at 38%–48% (BDC, benzenedicarboxylate; NDC, 1,8-naphthalene-dicarboxylate; TDC, p-terphenyl-4,4″-dicarboxylate). They were characterized by PXRD/FT-IR/TGA/photoluminescence spectroscopy, and the former two by SEM. These materials started decomposing at 330°C, while showing stability. The crystal structure of <bold>UAM-1</bold> was determined by PXRD, DFT calculations, and Rietveld refinement. In general, the structure was 3D, with the largest Ag-O bond interlinking 2D layers. The FT-IR spectra revealed 1450 and 1680 bands (cm<sup>−1</sup>) of asymmetrically stretching aniso-/iso-bidentate -COO in coordination with 2/3-Ag atoms, accompanied by Ag-O bands at 780–740 cm<sup>−1</sup>, all demonstrating the network formation. XRD and SEM showed nanometric-scale crystals in <bold>Ag₂BDC</bold>, and <bold>UAM-1</bold> developed micrometric single-stranded/agglomerated fibrillar particles of varying nanometric widths. Luminescence spectroscopy showed emission by <bold>Ag₂BDC</bold>, which was attributed to ligand-to-metal or ligand-to-metal–metal transitions, suggesting energy transfer due to the short distance between adjacent BDC molecules. <bold>UAM-1</bold> and <bold>UAM-2</bold> did not show luminescence emission attributable to ligand-to-metal transition; rather, they presented only UV emission. The stabilities of <bold>Ag₂BDC</bold> and <bold>UAM-1</bold> were evaluated in PBS/DMEM/DMEM+FBS media by XRD, which showed that they lost their crystallinity, resulting in AgCl due to soft–soft (Pearson’s principle) affinity.</p>