Concluding remarks: current and next generation MOFs

This paper describes the content of my “Concluding remarks” talk at the Faraday Discussion meeting on “MOFs for energy and the environment” (online, 23–25 June 2021). The panel consisted of sessions on the design of MOFs and MOF hybrids (synthetic chemistry), their applications (e.g., capture, storage, separation, electrical devices, photocatalysis), advanced characterization (e.g., transmission electron microscopy, solid-state nuclear magnetic resonance), theory and modeling, and commercialization. MOF chemistry is undergoing a significant evolution from simply network chemistry to the chemistry of synergistic integration with heterogeneous materials involving other disciplines (we call this the fourth generation type). As reflected in the papers of the invited speakers and discussions with the participants, the present and future of this field will be described in detail

Non–contact real–time detection of trace nitro-explosives by MOF composites visible–light chemiresistor

To create an artificial structure to remarkably surpass the sensitivity, selectivity and speed of the olfaction system of animals is still a daunting challenge. Herein, we propose a core-sheath pillar (CSP) architecture with a perfect synergistic interface that effectively integrates the advantages of metal–organic frameworks and metal oxides to tackle the above-mentioned challenge. The sheath material, NH₂-MIL-125, can concentrate target analyte, nitro-explosives, by 10¹² times from its vapour. The perfect band-matched synergistic interface enables the TiO₂ core to effectively harvest and utilize visible light. At room temperature and under visible light, CSP (TiO₂, NH₂-MIL-125) shows an unexpected self-promoting analyte-sensing behaviour. Its experimentally reached limit of detection (～0.8 ppq, hexogeon) is 10³ times lower than the lowest one achieved by a sniffer dog or all sensing techniques without analyte pre-concentration. Moreover, the sensor exhibits excellent selectivity against commonly existing interferences, with a short response time of 0.14 min

Soft corrugated channel with synergistic exclusive discrimination gating for CO₂ recognition in gas mixture

二酸化炭素に対してのみゲートを開いて吸着する フレキシブル多孔性材料を開発. 京都大学プレスリリース. 2023-08-02.Interactive networks for capturing gas with high selectivity. 京都大学プレスリリース. 2023-08-02.Developing artificial porous systems with high molecular recognition performance is critical but very challenging to achieve selective uptake of a particular component from a mixture of many similar species, regardless of the size and affinity of these competing species. A porous platform that integrates multiple recognition mechanisms working cooperatively for highly efficient guest identification is desired. Here, we designed a flexible porous coordination polymer (PCP) and realised a corrugated channel system that cooperatively responds to only target gas molecules by taking advantage of its stereochemical shape, location of binding sites, and structural softness. The binding sites and structural deformation act synergistically, exhibiting exclusive discrimination gating (EDG) effect for selective gate-opening adsorption of CO₂ over nine similar gas molecules, including N₂, CH₄, CO, O₂, H₂, Ar, C₂H₆, and even higher-affinity gases such as C₂H₂ and C₂H4. Combining in-situ crystallographic experiments with theoretical studies, it is clear that this unparalleled ability to decipher the CO₂ molecule is achieved through the coordination of framework dynamics, guest diffusion, and interaction energetics. Furthermore, the gas co-adsorption and breakthrough separation performance render the obtained PCP an efficient adsorbent for CO₂ capture from various gas mixtures

Selective sorption of oxygen and nitrous oxide by an electron donor-incorporated flexible coordination network

Incorporating strong electron donor functionality into flexible coordination networks is intriguing for sorption applications due to a built-in mechanism for electron-withdrawing guests. Here we report a 2D flexible porous coordination network, [Ni₂(4, 4′-bipyridine)(VTTF)₂]n(1) (where H₂VTTF = 2, 2′-[1, 2-bis(4-benzoic acid)-1, 2ethanediylidene]bis-1, 3-benzodithiole), which exhibits large structural deformation from the as-synthesized or open phase (1α) into the closed phase (1β) after guest removal, as demonstrated by X-ray and electron diffraction. Interestingly, upon exposure to electron-withdrawing species, 1β reversibly undergoes guest accommodation transitions; 1α⊃O₂ (90 K) and 1α⊃N₂O (185 K). Moreover, the 1β phase showed exclusive O₂ sorption over other gases (N₂, Ar, and CO) at 120 K. The phase transformations between the 1α and 1β phases under these gases were carefully investigated by in-situ X-ray diffraction, in-situ spectroscopic studies, and DFT calculations, validating that the unusual sorption was attributed to the combination of flexible frameworks and VTTF (electron-donor) that induces strong interactions with electron-withdrawing species

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

Xylene Recognition in Flexible Porous Coordination Polymer by Guest-Dependent Structural Transition

Xylene isomers are crucial chemical intermediates in great demand worldwide; the almost identical physicochemical properties render their current separation approach energy consuming. In this study, we utilized the soft porous coordination polymer (PCP)'s isomer-specific structural transformation, realizing o-xylene (oX) recognition/separation from the binary and ternary isomer mixtures. This PCP has a flexible structure that contains flexible aromatic pendant groups, which both work as recognition sites and induce structural flexibility of the global framework. The PCP exhibits guest-triggered "breathing"-type structural changes, which are accompanied by the rearrangement of the intraframework π-π interaction. By rebuilding π-π stacking with isomer species, the PCP discriminated oX from the other isomers by its specific guest-loading configuration and separated oX from the isomer mixture via selective adsorption. The xylene-selective property of the PCP is dependent on the solvent; in diluted hexane solution, the PCP favors p-xylene (pX) uptake. The separation results combined with crystallographic analyses revealed the effect of the isomer selectivity of the PCP on xylene isomer separation via structural transition and demonstrated its potential as a versatile selective adsorptive medium for challenging separations

Primary tumorectomy promotes angiogenesis and pulmonary metastasis in osteosarcoma-bearing nude mice

PURPOSE: To investigate the effect of primary tumorectomy on angiogenesis and pulmonary metastasis in osteosarcoma-bearing nude mice. METHODS: Osteosarcoma was introduced to nude mice via subcutaneous injection of MG-63 cells. One hundred and eighty osteosarcoma-bearing mice were used equally in 3 parallel experiments. The effect of tumorectomy (TR) on the expression of vascular endothelial growth factor (VEGF) and endostatin was investigated by ELISA. Meanwhile, the effect on angiogenesis was evaluated by Matrigel plug assay, and pulmonary metastasis assessed by calculating the metastatic foci. Sham-operation (SO) and untreated (UT) groups served as controls. RESULTS: The VEGF (TR: 79.55 ± 7.82 pg/mL vs. SO: 110.01 ± 5.69 pg/mL, UT: 123.50 ± 10.41 pg/mL; p < 0.01) and endostatin (TR: 47.09 ± 6.22 ng/mL vs. SO: 117.64 ± 7.39 ng/mL, UT: 126.73 ± 6.55 ng/mL; p<0.01) were down-regulated significantly after tumorectomy, and angiogenesis was significantly promoted simultaneously. The incidence of pulmonary metastatic foci was 80.0% in the TR group, 40.0% in the SO group and 35.0% in the UT group. CONCLUSION: Primary tumorectomy can down-regulate the expression of VEGF and endostatin and promote angiogenesis which leads to the acceleration of pulmonary metastasis. These findings imply that anti-angiogenic treatment can be considered after primary tumorectomy