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At least 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Solvent‐free Synthesis of Multi‐Module Pore‐Space‐Partitioned Metal‐Organic Frameworks for Gas Separation

Abstract Multi‐module design of framework materials with multiple distinct building blocks has attracted much attention because such materials are more amenable to compositional and geometrical tuning and thus offer more opportunities for property optimization. Few examples are known that use environmentally friendly and cost‐effective solvent‐free method to synthesize such materials. Here, we report the use of solvent‐free method (also modulator‐free) to synthesize a series of multi‐module MOFs with high stability and separation property for C 2 H 2 /CO 2 . The synthesis only requires simple mixing of reactants and short reaction time (2 h). Highly porous and stable materials can be made without any post‐synthetic activation. The success of solvent‐free synthesis of multi‐module MOFs reflects the synergy between different modules, resulting in stable pore‐partitioned materials, despite the fact that other competitive crystallization pathways with simpler framework compositions also exist.

Xiao, Yuchen↗
DOE OSTI2023

Beyond Solvothermal: Alternative Synthetic Methods for Covalent Organic Frameworks

Abstract Covalent organic frameworks (COFs) are crystalline porous organic materials that hold a wealth of potential applications across various fields. The development of COFs, however, is significantly impeded by the dearth of efficient synthetic methods. The traditional solvothermal approach, while prevalent, is fraught with challenges such as complicated processes, excessive energy consumption, long reaction times, and limited scalability, rendering it unsuitable for practical applications. The quest for simpler, quicker, more energy‐efficient, and environmentally benign synthetic strategies is thus paramount for bridging the gap between academic COF chemistry and industrial application. This Review provides an overview of the recent advances in alternative COF synthetic methods, with a particular emphasis on energy input. We discuss representative examples of COF synthesis facilitated by microwave, ultrasound, mechanic force, light, plasma, electric field, and electron beam. Perspectives on the advantages and limitations of these methods against the traditional solvothermal approach are highlighted.

Hu, Jiyun↗
DOE OSTI2021

Promoting the Furan Ring‐Opening Reaction to Access New Donor–Acceptor Stenhouse Adducts with Hexafluoroisopropanol

Abstract Donor–acceptor Stenhouse adducts (DASAs) are visible‐light‐responsive photoswitches with a variety of emerging applications in photoresponsive materials. Their two‐step modular synthesis, centered on the nucleophilic ring opening of an activated furan, makes DASAs readily accessible. However, the use of less reactive donors or acceptors renders the process slow and low yielding, which has limited their development. We demonstrate here that 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP) promotes the ring‐opening reaction and stabilizes the open isomer, allowing greatly reduced reaction times and increased yields for known derivatives. In addition, it provides access to previously unattainable DASA‐based photoswitches and DASA–polymer conjugates. The role of HFIP and the photochromic properties of a set of new DASAs is probed using a combination of 1 H NMR and UV/Vis spectroscopy. The use of sterically hindered, electron‐poor amines enabled the dark equilibrium to be decoupled from closed‐isomer half‐lives for the first time.

Clerc, Michèle↗
DOE OSTI2023

Solvent–free Synthesis of Multi–Module Pore–Space–Partitioned Metal–Organic Frameworks for Gas Separation

Multi-module design of framework materials with multiple distinct building blocks has attracted much attention because such materials are more amenable to compositional and geometrical tuning and thus offer more opportunities for property optimization. Few examples are known that use environmentally friendly and cost-effective solvent-free method to synthesize such materials. Here, we report the use of solvent-free method (also modulator-free) to synthesize a series of multi-module MOFs with high stability and separation property for C 2 H 2 /CO 2 . The synthesis only requires simple mixing of reactants and short reaction time (2 h). Highly porous and stable materials can be made without any post-synthetic activation. Here, the success of solvent-free synthesis of multi-module MOFs reflects the synergy between different modules, resulting in stable pore-partitioned materials, despite the fact that other competitive crystallization pathways with simpler framework compositions also exist.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Beyond Solvothermal: Alternative Synthetic Methods for Covalent Organic Frameworks

Abstract Covalent organic frameworks (COFs) are crystalline porous organic materials that hold a wealth of potential applications across various fields. The development of COFs, however, is significantly impeded by the dearth of efficient synthetic methods. The traditional solvothermal approach, while prevalent, is fraught with challenges such as complicated processes, excessive energy consumption, long reaction times, and limited scalability, rendering it unsuitable for practical applications. The quest for simpler, quicker, more energy‐efficient, and environmentally benign synthetic strategies is thus paramount for bridging the gap between academic COF chemistry and industrial application. This Review provides an overview of the recent advances in alternative COF synthetic methods, with a particular emphasis on energy input. We discuss representative examples of COF synthesis facilitated by microwave, ultrasound, mechanic force, light, plasma, electric field, and electron beam. Perspectives on the advantages and limitations of these methods against the traditional solvothermal approach are highlighted.

Hu, Jiyun↗
DOE OSTI2022

Advance modification of polyacrylonitrile nanofibers for enhanced removal of hexavalent chromium from water

Hexavalent chromium [Cr(VI)] is a known carcinogenic and mutagenic heavy metal. Its level in drinking water is regulated worldwide to protect public health. This work presents a novel chemical method to modify the polyacrylonitrile (PAN) nanofibers for efficient Cr(VI) removal from water. The PAN nanofibers with an average diameter of 165 nm are produced using the electrospinning technique. Through a 2-step chemical modification process, the amidine polyacrylonitrile (APAN) nanofibers are synthesized by the conversion of nitrile groups [—C≡N] in PAN nanofibers into amidines [—C(N=NH)(NH 2 )]. The attenuated total reflectance Fourier transform (ATR-FTIR) spectroscopy revealed the successful conversion of nitrile groups into amidoximes, resulting in amidoximated polyacrylonitrile nanofibers, and subsequent conversion into amidine functional groups, forming the APAN nanofibers. Greater concentration of hydroxylamine hydrochloride, increased reaction time and temperature yielded higher conversion of nitrile groups into amidoximes to a maximum of 37%. The Cr(VI) uptake by APAN nanofibers was found as a multilayer adsorption process modeled by Freundlich isotherm. The maximum Langmuir Cr(VI) adsorption capacity for APAN nanofibers was found as 225 mg g -1 at pH = 3.0 after 4.0 h exposure duration. The regeneration study revealed the excellent reusability of APAN nanofibers after five adsorption/desorption cycles.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Quantitative Analysis of The High‐Yield Hydrolysis of Kelp by Laminarinase and Alginate Lyase

Abstract Kelp is an abundant, farmable biomass‐containing laminarin and alginate as major polysaccharides, providing an excellent model substrate to study their deconstruction by simple enzyme mixtures. Our previous study showed strong reactivity of the glycoside hydrolase family 55 during hydrolysis of purified laminarin, raising the question of its reactivity with intact kelp. In this study, we determined that a combination of a single glycoside hydrolase family 55 β‐1,3‐exoglucanase with a broad‐specificity alginate lyase from the polysaccharide lyase family 18 gives efficient hydrolysis of untreated kelp to a mixture of simple sugars, that is, glucose, gentiobiose, mannitol‐end glucose, and mannuronic and guluronic acids and their soluble oligomers. Quantitative assignments from nanostructure initiator mass spectrometry (NIMS) and 2D HSQC NMR spectroscopy and analysis of the reaction time‐course are provided. The data suggest that binary combinations of enzymes targeted to the unique polysaccharide composition of marine biomass are sufficient to deconstruct kelp into soluble sugars for microbial fermentation.

2D HSQC NMR↗
DOE OSTI2018

Synthesis of l -[4- 11 C]Asparagine by Ring-Opening Nucleophilic 11 C-Cyanation Reaction of a Chiral Cyclic Sulfamidate Precursor

The development of a convenient and rapid method to synthesize radiolabeled enantiomerically pure amino acids (AAs) as potential positron emission tomography (PET) imaging agents for mapping various biochemical transformations in living organisms remains as a challenge. This is especially true for the synthesis of carbon-11 labeled AAs given the short half-life of carbon-11 ( 11 C, t 1/2 = 20.4 min). A facile synthetic pathway to prepare enantiomerically pure 11C-labeled L-asparagine was developed using a partially protected serine as a starting material with a four-step transformation providing a chiral fivemembered cyclic sulfamidate as the radiolabeling precursor. Its structure and absolute configuration were confirmed by X-Ray crystallography. Utilizing a [ 11 C]cyanide nucleophilic ring opening reaction followed by selective acidic hydrolysis and deprotection, enantiomerically pure L-[4- 11 C]asparagine was synthesized. Further optimization of reaction parameters, including base, metal ion source, solvent, acid component, reaction temperature and reaction time, a reliable two-step method for synthesizing L-[4- 11 C]asparagine was presented; within a 45 ± 3 min (n = 5, from end-of-bombardment), the desired enantiomerically pure product was synthesized with the initial nucleophilic cyanation yield of 69 ± 4% (n = 5) and overall two-step radiochemical yield of 53 ± 2% (n = 5) based on starting [ 11 C]HCN, and with radiochemical purity of 96 ± 2% (n = 5).

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Expanding the Scope of Pnictogen‐Assisted Cyclophane Self‐Assembly

Cyclophanes are a fundamentally interesting class of compounds that host a wide range of unique and emergent properties. Furthermore, synthesis of complex and/or functionalized cyclophanes can often suffer from harsh reaction conditions, long reaction times, and sometimes low yields using stepwise methods. We have previously reported an efficient, high-yielding, metalloid-directed self-assembly method to prepare disulfide, thioether, and hydrocarbon cyclophanes and cages that feature mercaptomethyl-arenes as starting materials. Herein, we report the synthesis of 21 new disulfide and thioether assemblies that expand this high yielding self-assembly method to a wide breadth of macrocycles and cages with diverse structures. Remarkably, the high-yielding, efficient syntheses still proceed under dynamic covalent control using electron-deficient, heteroaryl, cycloalkyl, spiro, and even short alkenyl/alkynyl substrates.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Molecular and morphological characterization of midblock-sulfonated styrenic triblock copolymers

Midblock-sulfonated triblock copolymers afford a desirable opportunity to generate network-forming amphiphilic materials that are suitable for use in a wide range of emerging technologies as fuel-cell, water-desalination, ion-exchange, photovoltaic, or electroactive membranes. Employing a previously reported synthetic strategy wherein poly( p - tert -butylstyrene) remains unreactive, we have selectively sulfonated the styrenic midblock of a poly( p - tert -butylstyrene- b -styrene- b - p - tert - butylstyrene) (TST) triblock copolymer to different extents. Comparison of the resulting sulfonated copolymers with results from our prior study provides favorable quantitative agreement and suggests that a shortened reaction time is advantageous. An ongoing challenge regarding the morphological development of charged block copolymers is the competition between microphase separation of the incompatible blocks and physical cross-linking of ionic clusters, with the latter often hindering the former. Here, we expose the sulfonated TST copolymers to solvent-vapor annealing to promote nanostructural refinement. Furthermore, the effect of such annealing on morphological characteristics, as well as on molecular free volume, is explored.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Nano Sb{sub 2}O{sub 3} catalyzed green synthesis, cytotoxic activity, and molecular docking study of novel α-aminophosphonates

Green synthesis of a series of novel dialkyl (aryl substituted)(2-fluoro-4-((2-methylcarbamoyl)pyridine-4-yl)oxy)phenyl)amino)methyl)phosphonates is accomplished by a simple and an efficient one pot three component reaction of 3-(4-amino-3-fluorobenzyl)-N-methylbenzamide with different substituted aromatic aldehydes and dialkyl phosphite in the presence of nano Sb{sub 2}O{sub 3} catalyst under solvent free conditions at 40–50 °C to obtain the title compounds. Excellent isolated product yields are obtained (85–95%) with high purity within shorter reaction times (30–60 min). The title compounds are characterized by IR, {sup 1}H, {sup 13}C, {sup 31}P-NMR and mass spectral data. The synthesized compounds are screened for their anticell-proliferation activity on seven cell lines, Control cells–HEK293 (human embryonic kidney), DU-145 (human prostate adenocarcinoma), MCF-7 (human ER+/PR+/Her2− breast cancer), MDA-MB-231 (human ER−/PR−/Her2− breast cancer), Mia-Paca-2 (human pancreatic carcinoma), HeLa (human cervical cancer) cells as well as HepG2 (human hepatocellular carcinoma) cancer cell lines using Sulforhodamine B (SRB) assay method. Docking studies were carried out for all these synthesized compounds against topoisomerase-II by using Auto dock method. Doxorubicin was taken as standard. Compounds 4a, 4c, 4d, 4e, 4h, 4i, 4k, and 4l exhibited higher cytotoxic activity than the standard doxorubicin. .

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Synthesis and bioassay of a new class of disubstituted 1,3,4-oxadiazoles, 1,3,4-thiadiazoles and 1,2,4-triazoles

A new class of aroylethenesulfonylmethyl styryl oxadiazoles/thiadiazoles/triazoles and arylsulfonylethenesulfonylmethyl styryl oxadiazoles/thiadiazoles/triazoles were synthesized from the synthetic intermediates E-aroylethenesulfonylacetic acid methyl ester, E-arylsulfonylethenesulfonylacetic acid methyl ester and substituted cinnamic acids adopting conventional and ultrasonication methodologies. All the synthesized compounds were obtained in higher yields and in shorter reaction times in ultrasound irradiation method when compared with conventional method. The structures of all the compounds were characterized by IR, {sup 1}H NMR, {sup 13}C NMR and mass spectra. All the title compounds were tested for antimicrobial activity. The arylsulfonylethenesulfonylmethyl styryl azoles displayed higher antimicrobial activity than the aroylethenesulfonylmethyl styryl azoles. The compounds having triazole moiety showed greater activity than those with oxadiazole and thiadiazole. Amongst all the tested compounds unsubstituted and chloro substituted arylsulfonylethenesulfonyl methyl styryl triazoles are identified as potential antimicrobial agents particularly against B. subtilis and P.chrysogenum. .

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Synthesis of novel α-aminophosphonates under microwave irradiation, biological evaluation as antiproliferative agents and apoptosis inducers

The synthesis of two series of α-aminophosphonates was achieved by Microwave Irradiation (MW), using the one-pot Kabachnik–Fields reaction. Based on a green chemistry approach, the reactions were carried out using ethanol as the only solvent and without any catalyst, and short reaction times (20–40 min), in variable yields. Both series were tested to determine their cell proliferation inhibition activity in MDA-MB-231, MCF-7 and MCF-10A cell lines. Ethyl 4-(((diphenoxyphosphoryl)(4-(diphenylamino)phenyl)methyl)amino) benzoate 4e and diphenyl (((4-(((S)-2-hydroxy-1-phenylethyl)carbamoyl)phenyl)amino)(4-hydroxyphenyl)methyl)phosphonate 6b, showed cell proliferation inhibition activity only in the cancer cell line MCF-7 and no effect on the normal cell line MFC-10A, both compounds caused cell death by inducing apoptosis.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Preparation of Ni—Mo/γ-Al{sub 2}O{sub 3} Catalysts by Vacuum Impregnation and Their Use for Hydrodesulfurization of Dibenzothiophene

A dual metal Ni—Mo/γ-Al{sub 2}O{sub 3} catalyst was prepared by saturated impregnation and H{sub 2} reduction pretreatment on γ-Al{sub 2}O{sub 3} support with Ni as the active component and Mo as the promoter. The support and catalysts were characterized using x-ray diffraction, hydrogen temperature-programmed reduction, and scanning electron microscopy. The catalytic properties for the reaction of dibenzothiophene (DBT) were investigated in a high-pressure reactor. The hydrodesulfurization (HDS) activity was comparable with those of advanced desulfurization catalysts FHUDS-5 and FHUDS-6. The Ni—Mo catalyst had excellent dispersion characteristics on the support. Synergism between Ni and Mo was greatest at a Ni/Mo molar ratio of 2:1. The DBT conversion on Ni—Mo/γ-Al{sub 2}O{sub 3} catalyst reached 100% at a reaction temperature of 300°C, pressure of 4 MPa, and reaction time of 150 min. The Ni—Mo/γ-Al{sub 2}O{sub 3}atalyst was significantly more active than the aforementioned two commercial FHUDS catalysts for HDS of DBT.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Highly Selective Recognition of Cd{sup 2+} by an Indole Derivative Chemosensor

A novel chemosensor exhibiting highly selective recognition of Cd {sup 2+} over other metal ions with significant fluorescence quenching was designed and synthesized by a click reaction of dialkyne and indole azide precursors. The compound was identified by {sup 1}H NMR, {sup 13}C NMR, MS, and UV-vis spectroscopy. The fluorescence quenching phenomenon was observed with the addition of Cd {sup 2+}. The reaction conditions, including the selectivity, the amount of Cd {sup 2+}, reaction time, and temperature, were optimized in the article. The product exerted highly selective fluorescence change in the presence of Cd {sup 2+} over other metal ions, such as Li{sup +}, Na{sup +}, K{sup +}, Pb{sup 2+}, Ni{sup 2+}, Zn{sup 2+}, Mn{sup 2+}, Hg{sup 2+}, Cr{sup 3+}, Cu{sup 2+}, and Fe{sup 3+}. Under the optimal conditions, a linearly proportional relationship between fluorescence intensity and the concentration of Cd{sup 2+} was revealed in the range from 0 to 7.226 × 10{sup –5} M. The limit of detection was 2.69 μM. The results suggest that the substance synthesized with 2-methylindole is a novel and quick detector for Cd {sup 2+}.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Fabrication of Biodegradable Superabsorbent Using RSM Design for Controlled Release of KNO{sub 3}

Present study envisaged the sequential experimental design approach for the development of biodegradable Gelatin-Tapoica/polyacrylamide superabsorbent. Percentage water uptake efficacy of candidate sample was optimized using Response Surface Methodology (RSM) design under microwave irradiation. Different process variables such as potassium persulphate and ammonium persulphate (KPS:APS) ratio, pH, reaction time concentration of acrylamide and N,N-methylene-bis-acrylamide (MBA) were investigated as a function of percentage swelling using sequential experimental design. Maximum liquid efficacy of 1550% was obtained at KPS:APS = 1.0:0.5; acrylamide = 7.67 × 10{sup −1} mol L{sup −1}; MBA = 1.76 × 10{sup −2} mol L{sup −1}; pH 10 and time = 110 s. The 3D crosslinked network formed was characterized using Fourier Transformation Infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopic (SEM) techniques and thermal stability was ensured by Thermal gravimetric Analysis/Differential Thermal Analysis/Differential Thermal Gravimetric (TGA/DTA/DTG) studies. Superabsorbent synthesized could increase the moisture content in different type of soils and was found to enhance the water-holding capability of the soil upto 60 days in clayey, 40 days in sandy and 51 days in mixture of two soils under controlled conditions. Further, candidate polymer was investigated for the in-vitro controlled release of the KNO{sub 3} with diffusion exponent ‘n’ was found to be 0.4326 indicating Fickian type diffusion. Also, initial diffusion coefficient (D{sub I} = 3.49 × 10{sup −5} m{sup 2} h{sup −1}) was found to be greater than the lateral diffusion coefficient (D{sub L} = 3.76 × 10{sup −6} m{sup 2} h{sup −1}) indicated rapid release of KNO{sub 3} during initial hours with slow release afterwards. The ecofriendly nature of the synthesized polymer was also tested by conducting biodegradation studies and it was found to degrade upto 94% and 88.1% within 70 days with degradation rate of 1.34 and 1.26% per day using composting method and vermicomposting method respectively. So, the synthesized candidate polymer was found to be boon for agriculture-horticulture sector with wide applicability.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Optimization of Beidellite/Polyaniline Production Conditions by Central Composite Design for Removal of Acid Yellow 194

In the adsorption process, the adsorbent structure and its interaction with wastewater are the main determinant of the process efficiency. For this reason, the correct selection of the production conditions for the produced adsorbents is critical. In this study, the reaction time and the concentration of acid, oxidant, substrate, and monomer were selected as independent variables which effect the structure of the polyaniline based composite material. These production variables of polyaniline/beidellite (PANI/BEI) composites were designed by response surface methodology (RSM). According to RSM, 46 different PANI/BEI composites were synthesized and were used as an adsorbent in the removal of acid yellow 194. Thus, the optimum PANI/BEI production conditions were determined. After the identification of the optimum PANI/BEI production conditions, the effect of adsorption conditions such as pH, mixing time, and dye concentration were studied by batch experiments. The maximum adsorption capacity was obtained as 123 (mg g{sup −1}) at the T = 25 °C, t = 24 h, pH 3, m{sub s} = 0.15 g adsorbent, V{sub s} = 50 ml dye solution, and ω = 200 rpm. The results presented in this study revealed that the central composite design is a suitable method to optimize the production conditions of PANI/BEI and the prepared PANI/BEI composites has an important potential as an adsorbent for the removal of metal-complex dyes such as AY194. In addition, the polymerization of aniline and the removal of dye were confirmed by different analytical techniques such as BET, XRD, SEM, and EDAX.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Completely Bio-based Polyol Production from Sunflower Stalk Saccharification Lignin Residue via Solvothermal Liquefaction Using Biobutanediol Solvent and Application to Biopolyurethane Synthesis

Sunflower stalk saccharification lignin residue was converted to a completely bio-based biopolyol via solvothermal liquefaction using acid catalyst. Different isomer-type biobutanediols were used to replace petroleum-derived reaction solvents. The reaction parameters were optimized according to measurement of the biomass conversion and the hydroxyl and acid numbers. The lignin-derived biopolyol with a biomass conversion of 80.1%, hydroxyl number of 819.0 mg KOH/g, and acid number of 26.5 mg KOH/g was produced in the optimal condition (reaction temperature of 120 °C, 4 wt% acid catalyst loading, reaction time of 120 min, and 25 wt% biomass loading). The lignin-derived biopolyol was neutralized to decrease the acid number. The neutralized biopolyol was used to synthesize biopolyurethane via polymerization with poly(propylene glycol), tolylene 2,4-diisocyanate terminated. Urethane bond formation was confirmed by FT-IR analysis. The biopolyurethane showed good thermal properties, such as a T{sub d5} of 273.4 °C, T{sub d10} of 305.8 °C, and a single degradation peak at 387.2 °C.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗