Thin-layer studies on surface functionalization of polyetherimide: Hydrolysis versus amidation

Computationally-Guided Investigation of Dual Amine/pi Lewis Acid Catalysts for Direct Additions of Aldehydes and Ketones to Unactivated Alkenes and Alkynes

10.26434/chemrxiv.7538114.v2 ◽

2020 ◽

Author(s):

Eric Greve ◽

Jacob D. Porter ◽

Chris Dockendorff

Keyword(s):

Lewis Acid ◽

Density Functional ◽

Acid Catalyst ◽

Metal Catalyst ◽

Catalyst Poisoning ◽

Lewis Acid Catalysts ◽

Metal Ligands ◽

Aldehydes And Ketones ◽

Lewis Acid Catalyst ◽

Catalyst Systems

Dual amine/pi Lewis acid catalyst systems have been reported for intramolecular direct additions of aldehydes/ketones to unactivated alkynes and occasionally alkenes, but related intermolecular reactions are rare and not presently of significant synthetic utility, likely due to undesired coordination of enamine intermediates to the metal catalyst. We reasoned that bulky metal ligands and bulky amine catalysts could minimize catalyst poisoning and could facilitate certain examples of direct intermolecular additions of aldehyde/ketones to alkenes/alkynes. Density Functional Theory (DFT) calculations were performed that suggested that PyBOX-Pt(II) catalysts for alkene/alkyne activation could be combined with MacMillan’s imidazolidinone organocatalyst for aldehyde/ketone activation to facilitate desirable C-C bond formations, and certain reactions were calculated to be more exergonic than catalyst poisoning pathways. As calculated, preformed enamines generated from the MacMillan imidazolidinone did not displace ethylene from a biscationic (t-Bu)PyBOX-Pt2+complex, but neither were the desired C-C bond formations observed under several different conditions.

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Computationally-Guided Investigation of Dual Amine/pi Lewis Acid Catalysts for Direct Additions of Aldehydes and Ketones to Unactivated Alkenes and Alkynes

10.26434/chemrxiv.7538114 ◽

2020 ◽

Author(s):

Eric Greve ◽

Jacob D. Porter ◽

Chris Dockendorff

Keyword(s):

Lewis Acid ◽

Density Functional ◽

Acid Catalyst ◽

Metal Catalyst ◽

Catalyst Poisoning ◽

Lewis Acid Catalysts ◽

Metal Ligands ◽

Aldehydes And Ketones ◽

Lewis Acid Catalyst ◽

Catalyst Systems

Dual amine/pi Lewis acid catalyst systems have been reported for intramolecular direct additions of aldehydes/ketones to unactivated alkynes and occasionally alkenes, but related intermolecular reactions are rare and not presently of significant synthetic utility, likely due to undesired coordination of enamine intermediates to the metal catalyst. We reasoned that bulky metal ligands and bulky amine catalysts could minimize catalyst poisoning and could facilitate certain examples of direct intermolecular additions of aldehyde/ketones to alkenes/alkynes. Density Functional Theory (DFT) calculations were performed that suggested that PyBOX-Pt(II) catalysts for alkene/alkyne activation could be combined with MacMillan’s imidazolidinone organocatalyst for aldehyde/ketone activation to facilitate desirable C-C bond formations, and certain reactions were calculated to be more exergonic than catalyst poisoning pathways. As calculated, preformed enamines generated from the MacMillan imidazolidinone did not displace ethylene from a biscationic (t-Bu)PyBOX-Pt2+complex, but neither were the desired C-C bond formations observed under several different conditions.

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Exploring the Structure–Performance Relationship of Sulfonated Polysulfone Proton Exchange Membrane by a Combined Computational and Experimental Approach

Polymers ◽

10.3390/polym13060959 ◽

2021 ◽

Vol 13 (6) ◽

pp. 959

Author(s):

Cataldo Simari ◽

Mario Prejanò ◽

Ernestino Lufrano ◽

Emilia Sicilia ◽

Isabella Nicotera

Keyword(s):

High Performance ◽

Mechanical Stability ◽

Structural Parameters ◽

Hydration Number ◽

Pem Fuel Cells ◽

Proton Exchange ◽

Water Dynamics ◽

Mechanical Resistance ◽

Theoretical Simulation ◽

Sulfonated Polysulfone

Sulfonated Polysulfone (sPSU) is emerging as a concrete alternative to Nafion ionomer for the development of proton exchange electrolytic membranes for low cost, environmentally friendly and high-performance PEM fuel cells. This ionomer has recently gained great consideration since it can effectively combine large availability on the market, excellent film-forming ability and remarkable thermo-mechanical resistance with interesting proton conductive properties. Despite the great potential, however, the morphological architecture of hydrated sPSU is still unknown. In this study, computational and experimental advanced tools are combined to preliminary describe the relationship between the microstructure of highly sulfonated sPSU (DS = 80%) and its physico-chemical, mechanical and electrochemical features. Computer simulations allowed for describing the architecture and to estimate the structural parameters of the sPSU membrane. Molecular dynamics revealed an interconnected lamellar-like structure for hydrated sPSU, with ionic clusters of about 14–18 Å in diameter corresponding to the hydrophilic sulfonic-acid-containing phase. Water dynamics were investigated by 1H Pulsed Field Gradient (PFG) NMR spectroscopy in a wide temperature range (20–120 °C) and the self-diffusion coefficients data were analyzed by a “two-sites” model. It allows to estimate the hydration number in excellent agreement with the theoretical simulation (e.g., about 8 mol H2O/mol SO3− @ 80 °C). The PEM performance was assessed in terms of dimensional, thermo-mechanical and electrochemical properties by swelling tests, DMA and EIS, respectively. The peculiar microstructure of sPSU provides a wider thermo-mechanical stability in comparison to Nafion, but lower dimensional and conductive features. Nonetheless, the single H2/O2 fuel cell assembled with sPSU exhibited better features than any earlier published hydrocarbon ionomers, thus opening interesting perspectives toward the design and preparation of high-performing sPSU-based PEMs.

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Direct coherent multi-ink printing of fabric supercapacitors

Science Advances ◽

10.1126/sciadv.abd6978 ◽

2021 ◽

Vol 7 (3) ◽

pp. eabd6978 ◽

Cited By ~ 1

Author(s):

Jingxin Zhao ◽

Hongyu Lu ◽

Yan Zhang ◽

Shixiong Yu ◽

Oleksandr I. Malyi ◽

...

Keyword(s):

System Integration ◽

High Performance ◽

Mechanical Stability ◽

Three Dimensional ◽

High Mass ◽

Wearable Electronics ◽

Energy Storage Devices ◽

Fabrication Procedure ◽

Self Powered ◽

Mechanical Devices

Coaxial fiber-shaped supercapacitors with short charge carrier diffusion paths are highly desirable as high-performance energy storage devices for wearable electronics. However, the traditional approaches based on the multistep fabrication processes for constructing the fiber-shaped energy device still encounter persistent restrictions in fabrication procedure, scalability, and mechanical durability. To overcome this critical challenge, an all-in-one coaxial fiber-shaped asymmetric supercapacitor (FASC) device is realized by a direct coherent multi-ink writing three-dimensional printing technology via designing the internal structure of the coaxial needles and regulating the rheological property and the feed rates of the multi-ink. Benefitting from the compact coaxial structure, the FASC device delivers a superior areal energy/power density at a high mass loading, and outstanding mechanical stability. As a conceptual exhibition for system integration, the FASC device is integrated with mechanical units and pressure sensor to realize high-performance self-powered mechanical devices and monitoring systems, respectively.

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Flexible and efficient perovskite quantum dot solar cells via hybrid interfacial architecture

Nature Communications ◽

10.1038/s41467-020-20749-1 ◽

2021 ◽

Vol 12 (1) ◽

Cited By ~ 1

Author(s):

Long Hu ◽

Qian Zhao ◽

Shujuan Huang ◽

Jianghui Zheng ◽

Xinwei Guan ◽

...

Keyword(s):

Thin Film ◽

Quantum Dots ◽

Solar Cells ◽

Quantum Dot ◽

High Performance ◽

Mechanical Stability ◽

Mechanical Adhesion ◽

Perovskite Quantum Dots ◽

Efficient Charge ◽

Photovoltaic Technologies

AbstractAll-inorganic CsPbI3 perovskite quantum dots have received substantial research interest for photovoltaic applications because of higher efficiency compared to solar cells using other quantum dots materials and the various exciting properties that perovskites have to offer. These quantum dot devices also exhibit good mechanical stability amongst various thin-film photovoltaic technologies. We demonstrate higher mechanical endurance of quantum dot films compared to bulk thin film and highlight the importance of further research on high-performance and flexible optoelectronic devices using nanoscale grains as an advantage. Specifically, we develop a hybrid interfacial architecture consisting of CsPbI3 quantum dot/PCBM heterojunction, enabling an energy cascade for efficient charge transfer and mechanical adhesion. The champion CsPbI3 quantum dot solar cell has an efficiency of 15.1% (stabilized power output of 14.61%), which is among the highest report to date. Building on this strategy, we further demonstrate a highest efficiency of 12.3% in flexible quantum dot photovoltaics.

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A Critical Review for an Accurate Electrochemical Stability Window Measurement of Solid Polymer and Composite Electrolytes

Materials ◽

10.3390/ma14143840 ◽

2021 ◽

Vol 14 (14) ◽

pp. 3840

Author(s):

Adrien Méry ◽

Steeve Rousselot ◽

David Lepage ◽

Mickaël Dollé

Keyword(s):

Ionic Conductivity ◽

Energy Density ◽

High Performance ◽

Mechanical Stability ◽

Electrochemical Stability ◽

Solid Polymer Electrolytes ◽

Solid Polymer ◽

Composite Electrolytes ◽

Battery System ◽

Electrochemical Stability Window

All-solid-state lithium batteries (ASSLB) are very promising for the future development of next generation lithium battery systems due to their increased energy density and improved safety. ASSLB employing Solid Polymer Electrolytes (SPE) and Solid Composite Electrolytes (SCE) in particular have attracted significant attention. Among the several expected requirements for a battery system (high ionic conductivity, safety, mechanical stability), increasing the energy density and the cycle life relies on the electrochemical stability window of the SPE or SCE. Most published works target the importance of ionic conductivity (undoubtedly a crucial parameter) and often identify the Electrochemical Stability Window (ESW) of the electrolyte as a secondary parameter. In this review, we first present a summary of recent publications on SPE and SCE with a particular focus on the analysis of their electrochemical stability. The goal of the second part is to propose a review of optimized and improved electrochemical methods, leading to a better understanding and a better evaluation of the ESW of the SPE and the SCE which is, once again, a critical parameter for high stability and high performance ASSLB applications.

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