Recent Submissions

  • Introducing a Cantellation Strategy for the Design of Mesoporous Zeolite-like Metal–Organic Frameworks: Zr-sod-ZMOFs as a Case Study

    Alsadun, Norah Sadun; Mouchaham, Georges; Guillerm, Vincent; Czaban-Jozwiak, Justyna; Shkurenko, Aleksander; Jiang, Hao; Bhatt, Prashant; Parvatkar, Prakash Tukaram; Eddaoudi, Mohamed (Journal of the American Chemical Society, American Chemical Society (ACS), 2020-11-19) [Article]
    Herein we report novel mesoporous zirconium-based metal-organic frameworks (MOFs) with zeolitic sodalite (sod) topology. Zr-sod-ZMOF-1 and -2 are constructed based on a novel cantellation design strategy. Distinctly, organic linkers are judiciously designed in order to promote the deployment of the 12-coordinated Zr hexanuclear molecular building block (MBB) as a tetrahedral secondary building unit, a prerequisite for zeolite-like nets. The resultant Zr-sod-ZMOFs exhibit mesopores with a diameter up to ≈43 Å, while the pore volume of 1.98 cm3·g-1 measured for Zr-sod-ZMOF-1 is the highest reported experimental value for zeolite-like MOFs based on MBBs as tetrahedral nodes.
  • Molecularly-porous ultrathin membranes for highly selective organic solvent nanofiltration

    Huang, Tiefan; Moosa, Basem; HOANG, PHUONG; Liu, Jiangtao; Chisca, Stefan; Zhang, Gengwu; Alyami, Mram Z.; Khashab, Niveen M.; Nunes, Suzana Pereira (Nature Communications, Springer Science and Business Media LLC, 2020-11-18) [Article]
    AbstractEngineering membranes for molecular separation in organic solvents is still a big challenge. When the selectivity increases, the permeability tends to drastically decrease, increasing the energy demands for the separation process. Ideally, organic solvent nanofiltration membranes should be thin to enhance the permeant transport, have a well-tailored nanoporosity and high stability in harsh solvents. Here, we introduce a trianglamine macrocycle as a molecular building block for cross-linked membranes, prepared by facile interfacial polymerization, for high-performance selective separations. The membranes were prepared via a two-in-one strategy, enabled by the amine macrocycle, by simultaneously reducing the thickness of the thin-film layers (<10 nm) and introducing permanent intrinsic porosity within the membrane (6.3 Å). This translates into a superior separation performance for nanofiltration operation, both in polar and apolar solvents. The hyper-cross-linked network significantly improved the stability in various organic solvents, while the amine host macrocycle provided specific size and charge molecular recognition for selective guest molecules separation. By employing easily customized molecular hosts in ultrathin membranes, we can significantly tailor the selectivity on-demand without compromising the overall permeability of the system.
  • Liquid nanoparticles: manipulating the nucleation and growth of nanoscale droplets.

    Wang, Ruoxu; Han, Fei; Chen, Bo; Liu, Lingmei; Wang, Shaoyan; Zhang, Hua; Han, Yu; Chen, Hongyu (Angewandte Chemie (International ed. in English), Wiley, 2020-11-15) [Article]
    By manipulating the nucleation and growth of solid materials, the synthesis of various sophisticated nanostructures has been achieved. Similar methodology, if applied to liquid, could enable the mass-production and control of ultra-small droplets at the scale of nanoparticles (10 -18  L or below). It would be highly desirable since droplets plays a fundamental role in numerous applications. Here we present a general strategy to synthesize and manipulate nanoscale droplets, similar to what has been done to solid nanoparticles in the classis solution-synthesis. It was achieved by a solute-induced phase separation which initiates the nucleation of droplets from a homogeneous solution. These liquid nanoparticles have great potentials to be manipulated like their solid counterparts, borrowing from the vast methodologies of nanoparticle synthesis, such as burst nucleation, seeded growth and co-precipitations. LNPs also serve as a general synthetic platform, to fabricate nanoreactors, drug-loaded carriers, and other hollow nanostructures with a variety of shell materials.
  • Architecting Neonicotinoid-Scavenging Nanocomposite Hydrogels for Environmental Remediation

    Alammar, Abdulaziz; Park, Sang-Hee; Ibrahim, Izwaharyanie; Arun, Deepak; Holtzl, Tibor; Dumée, Ludovic F.; Lim, Hong Ngee; Szekely, Gyorgy (Applied Materials Today, Elsevier, 2020-11-13) [Article]
    The ubiquitous presence of neonicotinoid insecticides in the environment poses potential health concerns across all biomes, aquatic systems, and food chains. This global environmental challenge requires robust, advanced materials to efficiently scavenge and remove these harmful neonicotinoids. In this work, we engineered nanocomposite hydrogels based on sustainable cellulose acetate for water treatment. The nanocomposite hydrogels were incorporated with small quantities of polymers of intrinsic microporosity (PIM-1) and graphene oxide (GO). We prepared the hydrogels using green solvents such as Cyrene and MeTHF via simple dropwise phase inversion. High adsorption capacity and fast kinetic behavior toward acetamiprid, clothianidin, dinotefuran, imidacloprid, and thiamethoxam were observed. We also developed a rapid and sustainable ultrasound-assisted regeneration method for the hydrogels. Molecular dynamics of the complex quaternary system revealed the synergistic effects of the components, and the presence of PIM-1 was found to increase the GO surface area available for neonicotinoid scavenging. We demonstrated the robustness and practicality of the nanocomposites in continuous environmental remediation by using the hydrogels to treat contaminated groundwater from the Adyar river in India. The presented methodology is adaptable to other contaminants in both aqueous environments and organic media.
  • Electropolymerized Conjugated Microporous Nanoskin Regulating Polysulfide and Electrolyte for High-Energy Li–S Batteries

    Guo, Dong; Li, Xiang; Wahyudi, Wandi; Li, Chunyang; Emwas, Abdul-Hamid M.; Hedhili, Mohamed N.; Li, Yangxing; Lai, Zhiping (ACS Nano, American Chemical Society (ACS), 2020-11-09) [Article]
    A popular practice in Li–S battery research is to utilize highly nanostructured hosts and excessive electrolytes to enhance sulfur-specific capacities. However, from the perspective of commercialization, this is a less meaningful approach in the pursuit of high-energy Li–S batteries. Herein, we report the fabrication of a nanoskin composed of a conjugated microporous polymer by electropolymerization to create a closed system for a sulfur cathode. The nanoskin is ultrathin, conductive, continuous, and contains uniform micropores of approximately 0.8 nm. The nanoskin sealing prevents the shuttling of polysulfide species without using the absorption effect, enhances the utilization of electrolytes, and allows a fast transport of lithium ions. As a result, the Li–S batteries comprising the cathode with nanoskin exhibit superior stability (∼86% capacity retention) under lean electrolyte conditions and a prolonged lifetime (1000 cycles). At a low electrolyte/sulfur ratio of 4 μL mg–1, the designed cathode delivered a practical energy density of over 300 Wh kg–1 without using any sophisticated hosts.
  • Fast-Dissolving Antibacterial Nanofibers of Cyclodextrin/Antibiotic Inclusion Complexes for Oral Drug Delivery

    Topuz, Fuat; Kilic, Mehmet E.; Durgun, Engin; Szekely, Gyorgy (Journal of Colloid and Interface Science, Elsevier BV, 2020-11) [Article]
    The widespread use of antibacterial electrospun nanofibers is mostly restricted due to their low loading capacity to carry antibiotics and the need to use toxic organic solvents to boost the antibiotic loading capacity. Nanofibers based on natural excipients, such as cyclodextrin (CD)-based nanofibers, can carry larger amounts of antibiotics while achieving better stability via inclusion complexation.
  • Nanofiber engineering of microporous polyimides through electrospinning: Influence of electrospinning parameters and salt addition

    Topuz, Fuat; Abdulhamid, Mahmoud A.; Holtzl, Tibor; Szekely, Gyorgy (Materials & Design, Elsevier BV, 2020-10-31) [Article]
    The electrospinning of high-performance polyimides (PI) has recently sparked great interest. In this study, we explore the effect of the electrospinning parameters — namely polymer concentration, voltage, tip-to-collector distance and flow rate — and salt addition on the diameter, morphology, and spinnability of electrospun PI nanofibers. Three different polyimides of intrinsic microporosity (PIM-PIs) with high Brunauer–Emmett–Teller (BET) ranging from 270 to 506 m2 g−1, and two microporous polyimides, were synthesized through the polycondensation of 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and aromatic diamines. The addition of tetraethylammonium bromide (TEAB) salt considerably increased the conductivity of all the PI solutions, significantly improved spinability, and resulted in thinner fibers. We also used molecular dynamic simulations to investigate the macromolecular mechanism of improved spinnability and fiber morphology in the presence of an ammonium salt. The small droplets detached from the parent droplet, followed by the rapid evaporation of the ions through the hydration effect, which facilitated the electrospinning. The resulting uniform nanofibers have great potential in environmental applications due to the presence of microporosity and hydrophobic pendant trifluoromethyl groups, which enhance the sorption performance of the fibers for hydrophobic species.
  • Synthesis and characterization of 6FDA/3,5-diamino-2,4,6-trimethylbenzenesulfonic acid-derived polyimide for gas separation applications

    Abdulhamid, Mahmoud A.; Genduso, Giuseppe; Ma, Xiaohua; Pinnau, Ingo (Separation and Purification Technology, Elsevier BV, 2020-10-23) [Article]
    A sulfonic acid-functionalized trimethyl-substituted polyimide was synthesized by reacting 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 3,5-diamino-2,4,6-trimethylbenzenesulfonic acid (TrMSA). The properties of 6FDA-TrMSA were compared to the related 6FDA-derived polyimide analogues made from 2,4,6-trimethylbenzene-1,3-diamine (6FDA-TrMPD) and 3,5-diamino-2,4,6-trimethylbenzene benzoic acid (6FDA-TrMCA). Compared to 6FDA-TrMPD and 6FDA-TrMCA, sulfonic acid functionalization resulted in significantly lower surface area, reduced fractional free volume, and tighter chain d-spacing. Consequently, 6FDA-TrMSA displayed lower gas permeabilities with a commensurate increase in permeability-based gas-pair selectivities. The enhanced CO2/CH4 selectivity of 6FDA-TrMSA was caused exclusively by higher diffusion selectivity, which was promoted by strong hydrogen bonding induced by the [sbnd]SO3H functionalization. Permeation experiments of 6FDA-TrMSA with a 1:1 CO2-CH4 mixture revealed the occurrence of competitive sorption effects (depressing CO2 gas permeability) and CO2-induced polymer matrix plasticization, which reduced the polymer selectivity by enhancing CH4 permeability. At ~20 atm total pressure, 6FDA-TrMSA showed a CO2 permeability of ~15 Barrer and an equimolar CO2/CH4 mixed-gas selectivity of 55, which are ~2-fold higher performance values than those of the state-of-the-art polymer used for industrial scale natural gas sweetening, i.e., cellulose triacetate.
  • Covalent Organic Framework Embedded with Magnetic Nanoparticles for MRI and Chemo-Thermotherapy

    Benyettou, Farah; Das, Gobinda; Nair, Anjana Ramdas; Prakasam, Thirumurugan; Shinde, Digambar; Sharma, Sudhir Kumar; Whelan, Jamie; Lalatonne, Yoann; Traboulsi, Hassan; Pasricha, Renu; Abdullah, Osama; Jagannathan, Ramesh; Lai, Zhiping; Motte, Laurence; Gándara, Felipe; Sadler, Kirsten C.; Trabolsi, Ali (Journal of the American Chemical Society, American Chemical Society (ACS), 2020-10-22) [Article]
    Nanoscale imine-linked covalent organic frameworks (nCOFs) were first loaded with the anticancer drug Doxorubicin (Dox), coated with magnetic iron oxide nanoparticles (γ-Fe2O3 NPs), and stabilized with a shell of poly(l-lysine) cationic polymer (PLL) for simultaneous synergistic thermo-chemotherapy treatment and MRI imaging. The pH responsivity of the resulting nanoagents (γ-SD/PLL) allowed the release of the drug selectively within the acidic microenvironment of late endosomes and lysosomes of cancer cells (pH 5.4) and not in physiological conditions (pH 7.4). γ-SD/PLL could efficiently generate high heat (48 °C) upon exposure to an alternating magnetic field due to the nCOF porous structure that facilitates the heat conduction, making γ-SD/PLL excellent heat mediators in an aqueous solution. The drug-loaded magnetic nCOF composites were cytotoxic due to the synergistic toxicity of Dox and the effects of hyperthermia in vitro on glioblastoma U251-MG cells and in vivo on zebrafish embryos, but they were not significantly toxic to noncancerous cells (HEK293). To the best of our knowledge, this is the first report of multimodal MRI probe and chemo-thermotherapeutic magnetic nCOF composites.
  • Electropolymerization of robust conjugated microporous polymer membranes for rapid solvent transport and narrow molecular sieving

    Zhou, Zongyao; Li, Xiang; Guo, Dong; Shinde, Digambar; Lu, Dongwei; Chen, Long; Liu, Xiaowei; Cao, Li; Aboalsaud, Ammar M.; Hu, Yunxia; Lai, Zhiping (Nature Communications, Springer Science and Business Media LLC, 2020-10-21) [Article]
    Abstract Pore size uniformity is one of the most critical parameters in determining membrane separation performance. Recently, a novel type of conjugated microporous polymers (CMPs) has shown uniform pore size and high porosity. However, their brittle nature has prevented them from preparing robust membranes. Inspired by the skin-core architecture of spider silk that offers both high strength and high ductility, herein we report an electropolymerization process to prepare a CMP membrane from a rigid carbazole monomer, 2,2’,7,7’-tetra(carbazol-9-yl)-9,9’-spirobifluorene, inside a robust carbon nanotube scaffold. The obtained membranes showed superior mechanical strength and ductility, high surface area, and uniform pore size of approximately 1 nm. The superfast solvent transport and excellent molecular sieving well surpass the performance of most reported polymer membranes. Our method makes it possible to use rigid CMPs membranes in pressure-driven membrane processes, providing potential applications for this important category of polymer materials.
  • Kinetic separation of C4 olefins using Y-fum-fcu-MOF with ultra-fine-tuned aperture size

    Assen, Ayalew H.; Virdis, Thomas; De Moor, Wannes; Moussa, Ali; Eddaoudi, Mohamed; Baron, Gino; Denayer, Joeri F.M.; BELMABKHOUT, Youssef (Chemical Engineering Journal, Elsevier BV, 2020-10-18) [Article]
    The separation of C4 olefin mixtures into pure components is one of the most challenging processes in chemical industries. Adsorption-based separation, using ultra-microporous materials, is considered as a viable alternative to reduce the operating cost of the currently employed but energy intensive distillation technique. The understanding of structural properties-relationships for C4 olefins separation using solid state materials is still lacking particularly for microporous materials with purely cage-based structures. Herein, the adsorptive separation of C4 olefins (butene isomers and 1,3-butadiene) by the microporous MOF, Y-fum-fcu-MOF, containing octahedral and tetrahedral cages with triangular pore aperture size (≈4.7 Å), is studied. The adsorption capacities of the MOF for C4 olefins were assessed by measuring the single component adsorption isotherms at 30 °C which led to very similar equilibrium adsorption uptakes at saturation for the components (excluding isobutylene). However, adsorption breakthrough curves collected at 25 °C and Pulse Gas Chromatography experiments, conducted to define the guest–host affinity at very low concentration (Henry's region), evidenced kinetically driven separation of C4 olefins by Y-fum-fcu-MOF. In fact, a strong relation between pores window size, kinetic diameter of the components and their adsorption behavior was observed. The breakthrough capacity decreases at increasing molecular size, allowing the separation of cis- and trans-2-butene despite the quite similar adsorption enthalpies for these components (42.0 and 37.7 kJ/mol, respectively).
  • Ion-Exchange Materials for Membrane Capacitive Deionization

    McNair, Robert; Szekely, Gyorgy; Dryfe, Robert A. W. (ACS ES&T Water, ACS, 2020-10-14) [Article]
    The scarcity of clean water is a problem affecting large parts of the world. In fact, the World Health Organization/UNICEF Joint Monitoring Programme for Water Supply, Sanitation and Hygiene (2019) estimates that up to 2.2 billion people lack access to safely managed drinking water services. To address this, desalination techniques such as reverse osmosis, flash distillation, and electrodialysis have been utilized to convert the plentiful amounts of salt water into consumable water supplies for the general population. In the past 15 years, membrane capacitive deionization (MCDI) has emerged as an alternative desalination technique that has since received extensive research attention. MCDI has sought to challenge benchmark methods such as reverse osmosis, removing salt by application of a voltage between two electrodes covered with ion-exchange membranes, all under ambient conditions. The incorporation of ion-exchange materials over electrodes in MCDI has been shown to maximize the desalination performance in terms of salt removal and energy efficiency. This review provides a comprehensive assessment of the developments relating to ion-exchange materials in MCDI. The fabrication and characterization methods of the materials have been outlined and compared with those of commercially available ion-exchange membranes where possible. A critical comparison of the ion-exchange materials has been conducted, and the commercial viability of the technologies has been evaluated. In light of the findings of the review, the authors have indicated future directions and action points the field should look to address in the coming years. It is hoped that the findings of this review can contribute to the large-scale commercialization and application of MCDI, which can improve aspects of water treatment and quality, contaminant removal, and sanitation on a global scale.
  • Peierls-type metal-insulator transition in carbon nanostructures

    Zhang, Bing; Zhang, Ting; Pan, Jie; Chow, Tsz Pong; Aboalsaud, Ammar M.; Lai, Zhiping; Sheng, Ping (Carbon, Elsevier BV, 2020-10-10) [Article]
    We report the observation of Peierls-type metal-insulator transition in carbon nanostructures formed by chemical vapor deposition inside the pore network of the ZSM-5 zeolite. The Raman spectrum of this nanocarbon@ZSM-5 indicates a clear signature of the radial breathing mode (RBM) for (3,0) carbon nanotubes that can constitute the carbon network segments. Electrical transport measurements on multiple few-micron-sized nanocarbon@ZSM-5 crystals showed metallic temperature dependence of resistance down to 30 K, at which point the resistance exhibited a sharp upturn that is accompanied by the opening of a quasigap at the Fermi level as indicated by the differential resistance measurements. Further Hall measurements have yielded both the sign of the charge carrier and its density. The latter demonstrated excellent consistency with the quasigap data. We employed first-principles calculations to verify that there can indeed be softening of the phonon modes in the (3,0) carbon nanotubes.
  • Investigating the Catalytic Active Sites of Mo/HZSM-5 and Their Deactivation During Methane Dehydroaromatization

    Wang, Ning; Dong, Xinglong; Liu, Lingmei; Cai, Dali; Wang, Jianjian; Hou, Yilin; Emwas, Abdul-Hamid M.; Gascon, Jorge; Han, Yu (SSRN Electronic Journal, Elsevier BV, 2020-10-09) [Article]
    Molybdenum supported on zeolite HZSM-5 (Mo/HZSM-5) is the most studied catalyst for methane dehydroaromatization (MDA). However, the nature of its catalytic active sites and their deactivation mechanisms remain unclear and controversial. Here we report new insights into this system, on the basis of advanced characterization and a rational design of experiments. We find that it is the size of the HZSM-5 crystal that determines the form and location of the catalytic active molybdenum carbide (MoCx) species, and thus the performance of Mo/HZSM-5; we also find that MoCx sites are preferentially deactivated over acid sites, when supported on nano-sized HZSM-5. These findings lead us to develop an “encapsulation” strategy, which effectively reconciles the deactivation rates at the MoCx sites and the acid sites, enabling a full utilization of both sites, and consequently leading to a 10-fold increase in catalyst lifetime and aromatics yield. Our results indicate that MoCx particles formed outside the micropores of HZSM-5, which are traditionally considered detrimental to the reaction, can serve as active sites for MDA, provided that they are properly protected from direct exposure to coke deposition. These findings allow us to design control experiments to answer an open question whether the acid sites, in addition to promoting the dispersion of Mo species, play a catalytic role in the MDA reaction, and the results show that acid sites are indeed essential for the conversion of methane.
  • Gas-sieving zeolitic membranes fabricated by condensation of precursor nanosheets

    Dakhchoune, Mostapha; Villalobos, Luis Francisco; Semino, Rocio; Liu, L. M.; Rezaei, Mojtaba; Schouwink, Pascal; Avalos, Claudia Esther; Baade, Paul; Wood, Vanessa; Han, Yu; Ceriotti, Michele; Agrawal, Kumar Varoon (Nature Materials, Springer Science and Business Media LLC, 2020-10-05) [Article]
    The synthesis of molecular-sieving zeolitic membranes by the assembly of building blocks, avoiding the hydrothermal treatment, is highly desired to improve reproducibility and scalability. Here we report exfoliation of the sodalite precursor RUB-15 into crystalline 0.8-nm-thick nanosheets, that host hydrogen-sieving six-membered rings (6-MRs) of SiO4 tetrahedra. Thin films, fabricated by the filtration of a suspension of exfoliated nanosheets, possess two transport pathways: 6-MR apertures and intersheet gaps. The latter were found to dominate the gas transport and yielded a molecular cutoff of 3.6 Å with a H2/N2 selectivity above 20. The gaps were successfully removed by the condensation of the terminal silanol groups of RUB-15 to yield H2/CO2 selectivities up to 100. The high selectivity was exclusively from the transport across 6-MR, which was confirmed by a good agreement between the experimentally determined apparent activation energy of H2 and that computed by ab initio calculations. The scalable fabrication and the attractive sieving performance at 250–300 °C make these membranes promising for precombustion carbon capture.
  • CO2/CH4 Pure- and Mixed-Gas Dilation and Sorption in Thin (∼500 nm) and Ultrathin (∼50 nm) Polymers of Intrinsic Microporosity

    Ogieglo, Wojciech; Genduso, Giuseppe; Rubner, Jens; Hofmann-Préveraud de Vaumas, Jacques; Wessling, Matthias; Pinnau, Ingo (Macromolecules, American Chemical Society (ACS), 2020-09-23) [Article]
    In this work, we present (i) the dilation and refractive index variation associated with changes in film density and (ii) gas uptake of pure CO2 and CH4, as well as their equimolar mixture in thin films of two polymers of intrinsic microporosity (PIMs), that is, PIM-1 and poly(trimethylsilyl)propyne (PTMSP). A conventional low-free-volume glassy polymer, cellulose triacetate, was also investigated as the reference material. All experiments were performed with ∼50 and ∼500 nm-thick films up to partial pressures of 25 bar using in situ interference-enhanced spectroscopic ellipsometry. In all cases, film thickness reduction promoted the collapse of the frozen-in free volume. Particularly for thin PIM-1 and PTMSP films, the CO2 and CH4 pure-gas uptakes were generally lower than in bulk samples. In the most extreme case of the ultrathin ∼50 nm PTMSP film, we could detect a strikingly similar qualitative behavior to the penetrant partial molar volume and dilation in rubbery polymers. Remarkably, in PIM-1, the collapse of the frozen-in free volume seemed to be opposed by its ultra-micropores (<7 Å), which was not the case in PTMSP with larger micropores (>10 Å). In mixed-gas experiments, the refractive index response of all investigated films closely followed the trend observed during CO2 pure-gas sorption. In both thickness ranges and throughout the entire pressure range, the samples dilated less in the multicomponent environment than under the corresponding ideal pure-gas conditions. We found this phenomenon consistent with the pure- and mixed-gas uptake behavior of PIM-1 and PTMSP bulk films reported in the literature.
  • Removal of Organic Micropollutants from Water by Macrocycle-Containing Covalent Polymer Networks

    Ji, Xiaofan; Wang, Hu; Wang, Hongyu; Zhao, Tian; Page, Zachariah A.; Khashab, Niveen M.; Sessler, Jonathan L. (Angewandte Chemie, Wiley, 2020-09-15) [Article]
    Access to clean drinking water is a recognized societal need that touches on the health and livelihood of millions of people worldwide. This is providing an incentive to develop new water-treatment technologies. Traditional technologies, while widespread, are usually inefficient at removing organic pollutants from sewage or so-called grey water. Macrocycle-containing covalent polymer networks have begun to attract attention in the context of water treatment owing to the inherent stability provided by the polymer backbones and their ability to capture micropollutant guests as the result of tunable macrocycle-based host–guest interactions. In this Minireview, we summarize recent advances (from 2016 to mid-2020) involving the removal of organic micropollutants from water using macrocycle-containing covalent polymer networks. An overview of future challenges within this subfield is also provided.
  • Removal of Organic Micropollutants from Water by Macrocycle-Containing Covalent Polymer Networks.

    Sessler, Jonathan L; Ji, Xiaofan; Wang, Hu; Wang, Hongyu; Zhao, Tian; Page, Zachariah A; Khashab, Niveen M. (Angewandte Chemie (International ed. in English), Wiley, 2020-09-15) [Article]
    Access to clean drinking water is a recognized societal need that touches on the health and livelihood of millions of people worldwide. This is providing an incentive to develop new water-treatment technologies. Traditional technologies, while widespread, are usually inefficient at removing organic pollutants from sewage or so-called grey water. Macrocycle-containing covalent polymer networks have begun to attract attention in the context of water treatment owing to the inherent stability provided by the polymer backbones and their ability to capture micropollutant guests as the result of tunable macrocycle-based host-guest interactions. In this minireview, we summarize recent advances (from 2016 to mid-2020) involving the removal of organic micropollutants from water using macrocycle-containing covalent polymer networks. An overview of future challenges within this subfield is also provided.
  • Extension of the Surface Organometallic Chemistry to Metal-Organic Framework: development of well-defined single site [(≡Zr-O-)W(=O)(CH2tBu)3] olefin metathesis catalyst.

    Thiam, Zeynabou; Abou-Hamad, Edy; Dereli, Busra; Liu, Lingmei; Emwas, Abdul-Hamid M.; Ahmad, Rafia; Jiang, Hao; Isah, Abdulrahman Adamu; Ndiaye, Papa Birame; Taoufik, Mostafa; Han, Yu; Cavallo, Luigi; Basset, Jean-Marie; Eddaoudi, Mohamed (Journal of the American Chemical Society, American Chemical Society (ACS), 2020-09-09) [Article]
    We report here the first step by step anchoring of a W(≡CtBu)(CH2 tBu)3 complex on a highly crystalline and mesoporous MOF, namely Zr-NU-1000, using Surface organometallic Chemistry (SOMC) concept and methodology. SOMC allowed us to selectively graft the complex on the Zr6 clusters and characterize the obtained single site material by using state of the art experimental methods including extensive solid-state NMR techniques and HAADF-STEM imaging. Further FT-IR spectroscopy revealed the presence of a W=O moiety arising from the in situ reaction of the W≡CtBu functionality with the coordinated water coming from the 8-connected hexanuclear Zr6 clusters. All the steps leading to the final grafted molecular complex have been identified by DFT. The obtained material was tested for gas phase and liquid phase olefin metathesis and exhibited higher catalytic activity than the corresponding catalysts synthesized by different grafting methods. This contribution establishes the importance of applying SOMC to MOF chemistry to get well defined single site catalyst on MOF inorganic secondary building units, in particular the in situ synthesis of W=O alkyl complexes from their W carbyne analogues.
  • Anti-Poisoning Electrode for Real-Time In-Situ Monitoring of Hydrogen Sulfide Release

    Jeromiyas, Nithiya; Mani, Veerappan; Chang, Pu-Chieh; Huang, Chih-Hung; Salama, Khaled N.; Huang, Sheng-Tung (Sensors and Actuators B: Chemical, Elsevier BV, 2020-09-06) [Article]
    Electrode poisoning and interferences from complex biological environments are major challenges in the development of in-situ H2S sensors. To circumvent these issues, herein a robust electrode based on reduced graphene oxide-molybdenum disulfide nanohybrid (RGO-MoS2) and polymerized o-phenylenediamine (POPD) is developed. The POPD/RGO-MoS2-modified electrode catalyzed H2S oxidation at a minimized overpotential (+ 0.15 V vs. Ag/AgCl). A new strategy based on inherent material properties was implemented to alleviate the electrode-poisoning problem. The nano-tailored interface blocks 2.5-fold surplus levels of interferences because of its exclusive size-exclusion property and electrostatic interactions. Moreover, this method with a response time of fewer than 5 s displayed a detection limit of 10 nM, which covers the endogenous H2S levels. Practicality tests in various biological media yielded valuable recoveries of 96.4–97.8%. The amounts of H2S released from the bacterial cells were quantified in real-time over a continuous time span of 5 h.

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