Chlorosulfonated Polyphenylene Ether Metal–Organic Framework Nanomaterial Composite Proton Exchange Membranes for Fuel Cells

Proton exchange membrane (PEM) is a key part of a PEM fuel battery. It is a challenge in the development of PEMs to enhance the proton conductivity. A series of chlorosulfonated polyphenylene ether (PPO–SO2–Cl)–metal–organic framework (MOF) nanomaterial composite membranes with high proton conductivity, named MOF-SO2–PPO, were prepared by anchoring Cr-MIL-101-NH2 nanoparticles in PPO–SO2–Cl through Hinsberg reaction. A directly physically doped membrane based on sulfonated poly(phenyl ether) (SPPO) and MOF, named MOF/SPPO, was also prepared. The water absorption, swelling ratio, ion exchange capacity, and proton conductivity of the two composite membranes were tested. The MOF-SO2–PPO membranes had better thermal stability and water absorption than the membranes formed by traditional doping. At 343 K and 98% relative humidity, MOF-SO2–PPO exhibited a high proton conductivity of 4.9 × 10–2 ± 2.3% S cm–1, which was 1.96 times that of MOF/SPPO. Furthermore, additional modification entailed anchoring the MOF, modified with ionic liquid, onto PPO–SO2–Cl, yielding IL-MOF-SO2–PPO-3 with optimal content. The proton conductivity of IL-MOF-SO2–PPO-3 surpassed that of SPPO by 24 times. This work provides feasible insights into the application of MOF nanomaterials to PEMs in fuel cells

High Proton Conductivity of the UiO-66-NH₂‑SPES Composite Membrane Prepared by Covalent Cross-Linking

A sulfonated poly(ethersulfone) (SPES)–metal–organic framework (MOF) film with excellent proton conductivity was synthesized by anchoring UiO-66-NH2 to the main chain of the aromatic polymer through the Hinsberg reaction. The chemical bond was formed between the amino group in MOFs and the −SO2Cl group in chlorosulfonated poly(ethersulfones) to conduct protons in the proton channel of the membrane, making the membrane have excellent proton conductivity. UiO-66-NH2 is successfully prepared as a result of the consistency of the experimental and simulated powder X-ray diffraction (PXRD) patterns of MOFs. The existence of absorption peaks of characteristic functional groups in Fourier transform infrared (FTIR) spectra proved the successful preparation of SPES, PES–SO2Cl, and a composite film. The results of the AC impedance test indicate that the composite film with a 3% mass fraction has the best proton conductivity of 0.215 S·cm–1, which is 6.2 times higher than that of the blended film without a chemical bond at 98% RH and 353 K. To our knowledge, there are rarely any reports on the preparation of a composite membrane by directly linking MOFs and the membrane matrix with chemical bonds. This work provides a good way to synthesize the highly conductive proton exchange film

High Proton Conductivity of a Cadmium Metal–Organic Framework Constructed from Pyrazolecarboxylate and Its Hybrid Membrane

A new type of metal–organic framework, [Cd2(pdc)­(H2O)­(DMA)2]n (pdc = 3,5-pyrazoledicarboxylic acid; DMA = dimethylamine), named Cd-MOF, was synthesized and characterized. There are regular rectangular pore channels containing a large number of dimethylamine cations in the crystal structure. AC impedance test results show the proton conductivity of Cd-MOF reaches 1.15 × 10–3 S cm–1 at 363 K and 98% RH. In order for its application in fuel cells, the Cd-MOF was introduced into a sulfonated polyphenylene oxide matrix to prepare a hybrid membrane, and the proton conductivity of the hybrid membrane has a high value of 2.64 × 10–1 S cm–1 at 343 K and 98% RH, which is higher than those of most MOF polymer hybrid membranes. The proton conductivity of the hybrid membrane of the SPPO polymer still maintains a certain degree of stability in a wide temperature range. To the best of our knowledge, it is the first proton exchange membrane that combines pyrazolecarboxylate cadmium MOFs and an SPPO polymer with high proton conductivity and good stability. This research may help to further develop the application of MOFs in the field of proton exchange membrane fuel cells

Bifunctional Metal–Organic Framework Functionalized by Dimethylamine Cations: Proton Conduction and Iodine Vapor Adsorption

A metal–organic framework, {Zn3(BTB)2(μ3-OH)­[(CH3)2NH2]­(H2O)}n (1), was synthesized based on H3BTB (1,3,5-tri­(4-carboxyphenyl)­benzene). An AC impedance test proves that 1 has a relatively high conductivity performance of 1.52 × 10–3 S·cm–1 at 338 K and 98% RH. The proton conductivity of the composite film 1@CS-9 (CS = chitosan) reaches 1.84 × 10–1 S·cm–1 at 328 K and 98% RH. In addition, 1 is discovered to have a good adsorption effect on iodine vapor, and the adsorption capacity reaches 726 mg·g–1. The multifunctionality caused by dimethylamine cations was investigated for the first time, which has implications for multifunctionality generated by host–guest molecules

Self-Assembly Bifunctional Tetranuclear Ln₂Ni₂ Clusters: Magnetic Behaviors and Highly Efficient Conversion of CO₂ under Mild Conditions

A series of heterometallic tetranuclear clusters, Ln2Ni2(NO3)4L4(μ3-OCH3)2·2(CH3CN) (Ln = Gd(1), Tb(2), Dy(3), Ho(4), Er(5); HL = methyl 3-methoxysalicylate), were synthesized solvothermally. The intramolecular synergistic effect of two metal centers of Ln(III) and Ni(II) and the exposed multimetallic sites serving as Lewis acid activators greatly increase the efficiency of the CO2 conversion, and the yield for cluster 3 can be achieved at 96% at atmospheric pressure and low temperature. In particular, the self-assembly multimetal center with polydentate ligand shows good generality and enhanced recyclability. The design of such 3d-4f heterometallic clusters provides an effective strategy for the conversion of CO2 under greener conditions. Meanwhile, magnetic investigations indicate that cluster 1 is a good candidate for magnetic refrigerant materials with a relatively large magnetocaloric effect (MCE) (−ΔSm = 28.5 J kg–1 K–1 at 3.0 K and 7.0 T), and cluster 3 shows single-molecular magnet behavior under zero dc field. Heterometallic clusters with special magnetic properties and good catalytic behavior for the conversion of CO2 are rare. Thus, they are potential bifunctional materials applied in practice

Anchoring of Fe-MIL-101-NH₂ to the Polymer Membrane Matrix through the Hinsberg Reaction to Promote Conductivity of SPEEK Membranes

SCPEEK@MOF proton exchange membranes, where SCPEEK is sulfinyl chloride polyether ether ketone and MOF is a metal–organic framework, were prepared by doping Fe-MIL-101-NH2 into polymers. The amino group in the MOF and the -SOCl2 group in thionyl chloride polyether ether ketone cross-link to form a covalent bond through the Hinsberg reaction, and the prepared composite membrane has stronger stability than other electrostatic interactions and simple physical doping composite membranes. The formation of covalent bonds improves the water absorption of the composite membrane, which makes it easy for water molecules to form hydrogen bonds. Moreover, SPEEK as a proton conductive polymer and the synergy of MOFs improve the proton conductivity of composite membranes. The composite membranes were characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The swelling rate, water absorption, mechanical stability, ion exchange capacity, and proton conductivity of the pure sulfonated polyether ether ketone (SPEEK) membrane were compared with those of the mechanically doped SPEEK/MOF membrane and the composite membrane SCPEEK@MOF doped with different ratios of Fe-MIL-101-NH2, and all of the SCPEEK@MOF showed superior performance. When the Fe-MIL-101-NH2 loading rate of the composite membrane is 2%, the proton conductivity of the composite membrane can reach 0.202 S cm–1 at 363 K and a 98% relative humidity, which is much higher than that of the SPEEK/MOF membrane obtained by simple physical doping under the same conditions

Dual-Functional Coordination Polymer with High Proton Conductivity and a Low-Detection-Limit Fluorescent Probe

A coordination polymer with dual functions of high proton conductivity and highly sensitive fluorescent sensors demonstrates a great application potential. In this work, a cadmium-based coordination polymer (denoted as CP 1) with hydrothermal stability was synthesized. The abundant coordination water, lattice water, and amino groups make an extended hydrogen-bonding pathway for efficient proton migration, which endows CP 1 with the highest proton conductivity of 2.41 × 10–3 S·cm–1 at 353 K and 98% RH. Especially, the proton conductivity of the chitosan (CS) hybrid membrane containing CP 1 reaches a maximum value of 2.62 × 10–2 S·cm–1 under 343 K and 98% RH, which increases almost 7 times higher than that of the pure CS membrane due to the host–guest collaboration. Furthermore, luminescence studies revealed that CP 1 is a high-sensitivity and good-selectivity fluorescent probe for the detection of trace amounts of l-histidine with a lowest detection limit of 1.0 × 10–8 M

A novel rare-earth nitronyl nitroxide radical complex as a high-efficiency sensor for Cr³⁺ and Cr₂O₇²⁻ ions in aqueous solutions

In this article, a new complex with formula [Eu(hfac)3(NITPh-DOMe)2] (1) (hfac =  hexafluoroacetylacetonate, NITPh-DOMe =2-(3′,4′-dioxylmethylene-phenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) has been successfully synthesized. Central Eu(III) ions of complex 1 are eight coordinated by two NITPh-DOMe radicals and three hexafluoroacetylacetonate ligands. The luminescent explorations show that complex 1 with high sensitivity, selectivity, almost linear at low concentration and the low detection limit for detection of Cr3+ (1 μM) and Cr2O72− (0.1 μM) ions in aqueous solutions.</p

Table1_Long-term efficacy and safety of sirolimus for retinal astrocytic hamartoma associated with tuberous sclerosis complex.DOCX

Mammalian target of rapamycin (mTOR) inhibitors (sirolimus or everolimus) have been demonstrated effective in reducing the size of tuberous sclerosis complex (TSC)-associated retinal astrocytic hamartoma (RAH) in short term. To investigate the long-term efficacy and safety of sirolimus on TSC-associated RAH, 13 TSC-associated RAH patients (59 RAH lesions) who received sirolimus therapy for at least 2 years were retrospectively enrolled in this study. Changes in the maximal thickness (MT) of RAH on optical coherence tomography and the longest base diameter (LBD) of RAH on color fundus photography were assessed. The results showed that for a mean follow-up of 39 months, sirolimus was associated with a mean reduction of 14.6% in MT and 6.8% in LBD of RAHs. The main impacts of sirolimus occurred within the first 6–12 months, with 14.8% reduction in MT and 4.7% reduction in LBD. Mouth ulceration (10 [76.9%]) and acne (9 [69.2%]) were the most common adverse events. These follow-up data support the long-term use of sirolimus in TSC-associated RAH patients, and persistent use of sirolimus possibly prevents tumor regrowth.</p

Table2_Long-term efficacy and safety of sirolimus for retinal astrocytic hamartoma associated with tuberous sclerosis complex.DOCX

Mammalian target of rapamycin (mTOR) inhibitors (sirolimus or everolimus) have been demonstrated effective in reducing the size of tuberous sclerosis complex (TSC)-associated retinal astrocytic hamartoma (RAH) in short term. To investigate the long-term efficacy and safety of sirolimus on TSC-associated RAH, 13 TSC-associated RAH patients (59 RAH lesions) who received sirolimus therapy for at least 2 years were retrospectively enrolled in this study. Changes in the maximal thickness (MT) of RAH on optical coherence tomography and the longest base diameter (LBD) of RAH on color fundus photography were assessed. The results showed that for a mean follow-up of 39 months, sirolimus was associated with a mean reduction of 14.6% in MT and 6.8% in LBD of RAHs. The main impacts of sirolimus occurred within the first 6–12 months, with 14.8% reduction in MT and 4.7% reduction in LBD. Mouth ulceration (10 [76.9%]) and acne (9 [69.2%]) were the most common adverse events. These follow-up data support the long-term use of sirolimus in TSC-associated RAH patients, and persistent use of sirolimus possibly prevents tumor regrowth.</p