Synthesis of Fluoro-Bridged Ho³⁺ and Gd³⁺ 1,3,5-Tris(4-carboxyphenyl)benzene Metal–Organic Frameworks from Perfluoroalkyl Substances

Abstract

A new fluoro-bridged rare-earth (RE) metal−organic framework consisting of 15-connected nonanuclear and 9-connected trinuclear clusters {[RE 9 -(μ 3 -F) 14 (H 2 O) 6 ][RE 3 (μ 3 -F)(H 2 O) 3 ](HCO 2 ) 3 -(BTB) 6 }•(solvent)x 2 (RE = Ho 3+ and Gd 3+ ) was synthesized through the transformation of a dimeric complex formulated as bis(2,2′-bipyridine)tetrakis(μ-2-fluorobenzoato-O,O′)-bis(2fluorobenzoato)diRE(III) 1 with the bridging linker 1,3,5-tris(4-carboxyphenyl)benzene (H 3 BTB). The rare-earth metal ions Ho 3+ and Gd 3+ were also found to remove fluorine from other organo-fluorine compounds such as perfluorohexanoic acid (PFHxA) and perfluorooctanoic acid (PFOA), resulting in the new fluorobridged RE-MOFs.

Lanthanide Metal–Organic Frameworks Exhibiting Fluoro-Bridged Extended Chains: Synthesis, Crystal Structures, and Magnetic Properties

“…The high-resolution O 1s spectra were also acquired for all samples as shown in Figures and S21. As shown in Figure b, Gd-BPDC-1 does not show any indication that there is M–O–M bonding within the structure, within the XPS sensitivity limit . The most prominent peak in the O 1s spectrum is from the C–O–M bond from the carboxylic group binding to the metal.…”

“…As shown in Figure 4b, Gd-BPDC-1 does not show any indication that there is M−O−M bonding within the structure, within the XPS sensitivity limit. 24 The most prominent peak in the O 1s spectrum is from the C−O−M bond from the carboxylic group binding to the metal. However, spectra of MOFs Tb-BPDC-1, Ho-BPDC-2, Gd-BPDC-2, and Tb-BPDC-2 reveal a small peak between 525 and 530 eV that is indicative of M−O−M binding.…”

“…The presence of a mixture of OH/F bridging found within these MOFs formed with 2-fba has been observed with other MOFs and appears to be dependent on the metal ion, linkers, and type of organofluorine modulator used. 24,31,46 Gas Adsorption. The pores of the MOFs were probed by using CO 2 and N 2 .…”

“…The popular modulator, 2-fluorobenzoic acid (2-fba), has been widely used to create lanthanide MOFs containing nona-, , hexa-, − and triclusters . The formation of such clusters can increase the chemical and thermal stability of the Ln MOFs. ,− Recently, it was reported that lanthanides react with the 2-fba and extract fluoride, , which becomes incorporated into the MOF structures as fluoro-bridges between the metal ions. − For example, Ho-UiO-66 contains a fluoro-bridged hexanuclear cluster when prepared using 2-fba …”

Encapsulation of cobaltocenium ions in a zeolite-like metal–organic framework

“…The applications of metal-organic frameworks (MOFs) have expanded into various fields including biomedical, 1-3 energy storage, [4][5][6] environmental, [7][8][9][10] sensors, [11][12][13][14] magnetism, [15][16][17] catalysis, [18][19][20] gas capture and storage, [21][22][23][24][25][26] etc. These applications depend in part on the discovery of new structures and methods.…”