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Proceedings of the National Academy of... Aug 2022Metallic charge transport and porosity appear almost mutually exclusive. Whereas metals demand large numbers of free carriers and must have minimal impurities and...
Metallic charge transport and porosity appear almost mutually exclusive. Whereas metals demand large numbers of free carriers and must have minimal impurities and lattice vibrations to avoid charge scattering, the voids in porous materials limit the carrier concentration, provide ample space for impurities, and create more charge-scattering vibrations due to the size and flexibility of the lattice. No microporous material has been conclusively shown to behave as a metal. Here, we demonstrate that single crystals of the porous metal-organic framework Ln(2,3,6,7,10,11-hexaoxytriphenylene) (Ln = La, Nd) are metallic. The materials display the highest room-temperature conductivities of all porous materials, reaching values above 1,000 S/cm. Single crystals of the compounds additionally show clear temperature-deactivated charge transport, a hallmark of a metallic material. Lastly, a structural transition consistent with charge density wave ordering, present only in metals and rare in any materials, provides additional conclusive proof of the metallic nature of the materials. Our results provide an example of a metal with porosity intrinsic to its structure. We anticipate that the combination of porosity and chemical tunability that these materials possess will provide a unique handle toward controlling the unconventional states that lie within them, such as charge density waves that we observed, or perhaps superconductivity.
PubMed: 35969747
DOI: 10.1073/pnas.2205127119 -
Angewandte Chemie (International Ed. in... Oct 2022The desire to construct complex molecular systems is driven by the need for technological (r)evolution and our intrinsic curiosity to comprehend the origin of life.... (Review)
Review
The desire to construct complex molecular systems is driven by the need for technological (r)evolution and our intrinsic curiosity to comprehend the origin of life. Supramolecular chemists tackle this challenge by combining covalent and noncovalent reactions leading to multicomponent systems with emerging complexity. However, this synthetic strategy often coincides with difficult preparation protocols and a narrow window of suitable conditions. Here, we report on unsuspected observations of our group that highlight the impact of subtle "irregularities" on supramolecular systems. Based on the effects of pathway complexity, minute amounts of water in organic solvents or small impurities in the supramolecular building block, we discuss potential pitfalls in the study of complex systems. This article is intended to draw attention to often overlooked details and to initiate an open discussion on the importance of reporting experimental details to increase reproducibility in supramolecular chemistry.
Topics: Reproducibility of Results; Solvents; Water
PubMed: 36062929
DOI: 10.1002/anie.202206738 -
Nature Materials Feb 2021Commercial carbazole has been widely used to synthesize organic functional materials that have led to recent breakthroughs in ultralong organic phosphorescence,...
Commercial carbazole has been widely used to synthesize organic functional materials that have led to recent breakthroughs in ultralong organic phosphorescence, thermally activated delayed fluorescence, organic luminescent radicals and organic semiconductor lasers. However, the impact of low-concentration isomeric impurities present within commercial batches on the properties of the synthesized molecules requires further analysis. Here, we have synthesized highly pure carbazole and observed that its fluorescence is blueshifted by 54 nm with respect to commercial samples and its room-temperature ultralong phosphorescence almost disappears. We discover that such differences are due to the presence of a carbazole isomeric impurity in commercial carbazole sources, with concentrations <0.5 mol%. Ten representative carbazole derivatives synthesized from the highly pure carbazole failed to show the ultralong phosphorescence reported in the literature. However, the phosphorescence was recovered by adding 0.1 mol% isomers, which act as charge traps. Investigating the role of the isomers may therefore provide alternative insights into the mechanisms behind ultralong organic phosphorescence.
Topics: Carbazoles; Temperature
PubMed: 32958877
DOI: 10.1038/s41563-020-0797-2 -
Environmental Science and Pollution... Feb 2023The presence of organic impurities hinders the resource utilization of industrial waste salt (IWS). In this study, pyrolysis treatment was chosen to remove these organic...
The presence of organic impurities hinders the resource utilization of industrial waste salt (IWS). In this study, pyrolysis treatment was chosen to remove these organic impurities. The optimal process parameters for the pyrolysis of organic impurities were as follows: a temperature of 500 °C and a holding time of 20 min. Under these optimal conditions, the total organic carbon (TOC) removal rate was 96.32%, inducing a decrease in the TOC mass fraction from 1.88 to 0.08%. Fourier transform infrared spectroscopy (FTIR) results obtained during this process showed that prolonging the pyrolysis time (10-70 min) for IWS resulted in a gradual decrease in the relative content of characteristic functional group, such as C-O in ether groups, and the disappearance of functional group, such as benzophenone carbonyl group and ester carbonyl. Organic impurities can release gas-containing compounds that destroy the initially smooth IWS surface, and the resulting particles with rough and irregular shapes fuse into large or lumpy particles during the pyrolysis process. GC‒MS results clearly showed that the number of different semivolatile organic compounds in the IWS was reduced from 35 to 19 as a result of the pyrolysis process. Correspondingly, organic impurities with molecular formulas containing 5-10 carbon atoms converted into compounds containing 6-20 carbon atoms. These findings provide theoretical support for IWS resource utilization.
Topics: Industrial Waste; Pyrolysis; Temperature; Spectroscopy, Fourier Transform Infrared; Carbon; Sodium Chloride; Sodium Chloride, Dietary
PubMed: 36272002
DOI: 10.1007/s11356-022-23659-5 -
Angewandte Chemie (International Ed. in... Feb 2023Commercially available stock solutions of organolithium reagents are well-implemented tools in organic and organometallic chemistry. However, such solutions are...
Commercially available stock solutions of organolithium reagents are well-implemented tools in organic and organometallic chemistry. However, such solutions are inherently contaminated with lithium halide salts, which can complicate certain synthesis protocols and purification processes. Here, we report the isolation of chloride-free methyllithium employing K[N(SiMe ) ] as a halide-trapping reagent. The influence of distinct LiCl contaminations on the Li-NMR chemical shift is examined and their quantification demonstrated. The structural parameters of new chloride-free monomeric methyllithium complex [(Me TACN)LiCH ], ligated by an azacrown ether, are assessed by comparison with a halide-contaminated variant and monomeric lithium chloride [(Me TACN)LiCl], further emphasizing the effect of halide impurities.
PubMed: 36409199
DOI: 10.1002/anie.202214599 -
Geochimica Et Cosmochimica Acta Sep 2021Biogenic iron (Fe) (oxyhydr)oxides (BIOS) partially control the cycling of organic matter, nutrients, and pollutants in soils and water via sorption and redox reactions....
Biogenic iron (Fe) (oxyhydr)oxides (BIOS) partially control the cycling of organic matter, nutrients, and pollutants in soils and water via sorption and redox reactions. Although recent studies have shown that the structure of BIOS resembles that of two-line ferrihydrite (2LFh), we lack detailed knowledge of the BIOS local coordination environment and structure required to understand the drivers of BIOS reactivity in redox active environments. Therefore, we used a combination of microscopy, scattering, and spectroscopic methods to elucidate the structure of BIOS sampled from a groundwater seep in North Carolina and compare them to 2LFh. We also simulated the effects of wet-dry cycles by varying sample preparation (e.g., freezing, flash freezing with freeze drying, freezing with freeze drying and oven drying). In general, the results show that both the long- and short-range ordering in BIOS are structurally distinct and notably more disordered than 2LFh. Our structure analysis, which utilized Fe K-edge X-ray absorption spectroscopy, Mössbauer spectroscopy, X-ray diffraction, and pair distribution function analyses, showed that the BIOS samples were more poorly ordered than 2LFh and intimately mixed with organic matter. Furthermore, pair distribution function analyses resulted in coherent scattering domains for the BIOS samples ranging from 12-18 Å, smaller than those of 2LFh (21-27 Å), consistent with reduced ordering. Additionally, Fe L-edge XAS indicated that the local coordination environment of 2LFh samples consisted of minor amounts of tetrahedral Fe(III), whereas BIOS were dominated by octahedral Fe(III), consistent with depletion of the sites due to small domain size and incorporation of impurities (e.g., organic C, Al, Si, P). Within sample sets, the frozen freeze dried and oven dried sample preparation increased the crystallinity of the 2LFh samples when compared to the frozen treatment, whereas the BIOS samples remained more poorly crystalline under all sample preparations. This research shows that BIOS formed in circumneutral pH waters are poorly ordered and more environmentally stable than 2LFh.
PubMed: 34305159
DOI: 10.1016/j.gca.2021.05.059 -
Biomedical Chromatography : BMC Oct 2022Amitriptyline hydrochloride is an antidepressant drug with sedative effects used to treat the symptoms of anxiety, agitation with depression and schizophrenia with...
Stability-indicating liquid chromatography method development for assay and impurity profiling of amitriptyline hydrochloride in tablet dosage form and forced degradation study.
Amitriptyline hydrochloride is an antidepressant drug with sedative effects used to treat the symptoms of anxiety, agitation with depression and schizophrenia with depression. A reversed-phase high-performance liquid chromatography method was developed to separate and quantitatively determine the assay and four organic impurities of amitriptyline in tablet dosage form and bulk drugs using a C column in an isocratic elution mode with mobile phase consisting of a mixture of pH 7.5 phosphate buffer and methanol. The pH conditions used in the chromatographic separation are discussed. The stability-indicating characteristics of the proposed method were proved using stress testing [5 m HCl at 80°C/1 h, 5 m NaOH at 80°C/1 h, H O (v/w) at 80°C/1 h, 6% H O (v/v) at 25°C/1 h, dry heat at 105°C/24 h and UV-vis light/4 days] and validated for specificity, detection limit, quantitation limit, linearity, precision, accuracy and robustness. For amitriptyline and its four known organic impurities, the quantitation limits, linearity and recoveries were in the ranges 0.25-3.0 μg/ml (r > 0.999) and 87.9-107.6%, respectively. The mass (m/z) spectral data of amitriptyline hydrochloride and its impurity are discussed. The proposed LC method is also suitable for impurity profiling and assay determination of amitriptyline in bulk drugs and pharmaceutical formulations.
Topics: Amitriptyline; Chromatography, High Pressure Liquid; Chromatography, Liquid; Drug Stability; Tablets
PubMed: 35766584
DOI: 10.1002/bmc.5436 -
Nanomaterials (Basel, Switzerland) Feb 2021This review summarizes the recent research efforts and developments in nanomaterials for sensing volatile organic compounds (VOCs). The discussion focuses on key... (Review)
Review
This review summarizes the recent research efforts and developments in nanomaterials for sensing volatile organic compounds (VOCs). The discussion focuses on key materials such as metal oxides (e.g., ZnO, SnO, TiO WO), conductive polymers (e.g., polypyrrole, polythiophene, poly(3,4-ethylenedioxythiophene)), and carbon-based materials (e.g., graphene, graphene oxide, carbon nanotubes), and their mutual combination due to their representativeness in VOCs sensing. Moreover, it delves into the main characteristics and tuning of these materials to achieve enhanced functionality (sensitivity, selectivity, speed of response, and stability). The usual synthesis methods and their advantages towards their integration with microsystems for practical applications are also remarked on. The literature survey shows the most successful systems include structured morphologies, particularly hierarchical structures at the nanometric scale, with intentionally introduced tunable "decorative impurities" or well-defined interfaces forming bilayer structures. These groups of modified or functionalized structures, in which metal oxides are still the main protagonists either as host or guest elements, have proved improvements in VOCs sensing. The work also identifies the need to explore new hybrid material combinations, as well as the convenience of incorporating other transducing principles further than resistive that allow the exploitation of mixed output concepts (e.g., electric, optic, mechanic).
PubMed: 33671783
DOI: 10.3390/nano11020552 -
Journal of Hazardous Materials Aug 2021The recovery of waste glass is an important issue in the fields of social sustainable development and resource recovery. The removal of organic impurity is the first...
The recovery of waste glass is an important issue in the fields of social sustainable development and resource recovery. The removal of organic impurity is the first step in the recovery of waste glass. Currently, desiccation-dissociation technology is advised to remove the organic impurity from waste glass. However, the risks of the organic impurity desiccation-dissociation process of waste glass have not been reported in the literature. In this paper, the environmental risks of the organic impurity desiccation-dissociation process of waste glass were assessed. The assessment results indicated that none of TSP (0.143 mg/m), PM (0.090 mg/m), heavy metals in air and residue after desiccation-dissociation were contaminated. However, the gas contained abundant organic contaminants, especially benzene, whose content was up to 5.26%. Molecular dynamics simulation and contaminant formation pathways analysis indicated that the formation of gaseous organic contaminants was because overmuch small molecular free radicals were generated at 200 °C and combined with each other. Hence, reducing the temperature of desiccation-dissociation, wearing gas masks, and placing organic gas contaminant absorption liquids are necessary protective measures. This paper provides scientific data for the green development of organic impurity desiccation-dissociation technology of waste glass. Meanwhile, this paper makes up for the shortage of the environmental information of the organic impurity desiccation-dissociation of waste glass.
Topics: Desiccation; Metals, Heavy
PubMed: 34492821
DOI: 10.1016/j.jhazmat.2021.125881 -
Dalton Transactions (Cambridge, England... Nov 2023An organic cation lacking specificity in its structure-directing action offers the possibility, through the screening of other structure-directing parameters, to...
An organic cation lacking specificity in its structure-directing action offers the possibility, through the screening of other structure-directing parameters, to synthesize a variety of zeolites. In this work we show that the organic structure-directing agent 2-isopropyl-1,3-dimethylimidazolium (2iPr13DMI) can produce up to seven different zeolite phases depending on water concentration, the presence of inorganic impurities, crystallization temperature and time, and germanium molar fraction. The obtained phases are very different in terms of pore system, connectivity of the zeolite structure and structural units. At the pure SiO side, ZSM-12 and SSZ-35 dominate, with ZSM-12 being favored by the presence of potassium impurities and by less concentrated conditions. The introduction of Ge at low levels favors SSZ-35 over ZSM-12 and as the Ge fraction increases it successively affords CSV, -CLO and two distinct UOS zeolites, HPM-11 and HPM-6. These two zeolites have the same topology but distinct chemical compositions and display powder X-ray diffraction patterns that are much different from each other and from that of as-synthesized IM-16 (UOS reference material). They also show different symmetry at 96 K. Rietveld refinements of the three as-made UOS materials mentioned are provided. HPM-6 and HPM-11 are produced in distinct, non-adjacent crystallization fields. The frequent cocrystallization of the chiral STW zeolite, however, did not afford its synthesis as a pure phase. Molecular mechanics simulations of the location of the organic cation and host-guest interactions fail to explain the observed trends, but also considering the intrinsic stability of the zeolites and the effect of germanium help to rationalize the results. The study is completed by DFT calculations of the NMR chemical shifts of C in UOS (helping to understand splittings in the spectrum) and F in CSV (supporting the location of fluoride inside the new [45], which is an incomplete double 4-ring).
PubMed: 37791957
DOI: 10.1039/d3dt02414h