Lewis Base Adduct Stabilized Organogallium Azides:  Synthesis and Dynamic NMR Spectroscopic Studies of Novel Precursors to Gallium Nitride and Role of Ammonia as Reactive Carrier Gas

1996 ◽  
Vol 15 (8) ◽  
pp. 2053-2059 ◽  
Author(s):  
Alexander Miehr ◽  
Mike R. Mattner ◽  
Roland A. Fischer
Keyword(s):  
Gallium Nitride ◽  
Spectroscopic Studies ◽  
Lewis Base ◽  
Dynamic Nmr ◽  
Carrier Gas

Can the Lewis basicity of an isolated solvent molecule be used for characterizing solvent effects?

2020 ◽  
Vol 16 ◽  
Author(s):  
Jean-François Gal ◽  
Pierre-Charles Maria
Keyword(s):  
Solvent Effects ◽  
Molecular Level ◽  
Solvent Molecule ◽  
Lewis Base ◽  
Bulk Liquid ◽  
Donor Number ◽  
Special Focus ◽  
Solution Processes ◽  
Inert Solvent

Background: The ubiquitous Lewis acid/base interactions are important in solution processes. Analytical chemistry may benefit of a better understanding of the role of Lewis basicity, at the molecular level or acting through a bulk solvent effect. Objective: To clearly delineate (i) the basicity at a molecular level, hereafter referred as solute basicity, and (ii) the solvent basicity, which is a bulk-liquid property. Method: The literature that relates Lewis basicity scales and solvent effects is analyzed. A special focus is placed on two extensive scales, the Donor Number, DN, and the BF3 affinity scale, BF3A, which were obtained by calorimetric measurement on molecules as solutes diluted in a quasi-inert solvent, and therefore define a molecular Lewis basicity. We discuss the validity of these solute scales when regarded as solvent scales, in particular when the basicity of strongly associated liquids is discussed. Results: We demonstrate the drawbacks of confusing the Lewis basicity of a solvent molecule, isolated as solute, and that of the bulk liquid solvent itself. Conclusion: Consequently, we recommend a reasoned use of the concept of Lewis basicity taking clearly into account the specificity of the process for which a Lewis basicity effect may be invoked. In particular, the action of the Lewis base, either as an isolated entity, or as a bulk liquid, must be distinguished.

Structural, magnetic and Mössbauer spectroscopic studies of the [Fe(3-bpp)2](CF3COO)2 complex: role of crystal packing leading to an incomplete Fe(ii) high spin ⇋ low spin transition

CrystEngComm ◽  
2021 ◽  
Vol 23 (15) ◽  
pp. 2854-2861
Author(s):  
Kristian Handoyo Sugiyarto ◽  
Djulia Onggo ◽  
Hiroki Akutsu ◽  
Varimalla Raghavendra Reddy ◽  
Hari Sutrisno ◽  
...  
Keyword(s):  
High Spin ◽  
Crystal Packing ◽  
Spin Transition ◽  
Spectroscopic Studies ◽  
Mononuclear Complex

Mononuclear complex [Fe(3-bpp)2](CF3COO)2 exhibits a thermal (HS + HS) ⇋ (HS + LS) transition at ∼226 K which is not associated with any crystallographic transition.

scholarly journals Gallium nitride catalyzed the direct hydrogenation of carbon dioxide to dimethyl ether as primary product

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chang Liu ◽  
Jincan Kang ◽  
Zheng-Qing Huang ◽  
Yong-Hong Song ◽  
Yong-Shan Xiao ◽  
...  
Keyword(s):  
Gallium Nitride ◽  
Dimethyl Ether ◽  
High Performance ◽  
Density Functional ◽  
Value Added ◽  
Density Functional Theory Calculations ◽  
Product Distribution ◽  
Spectroscopic Studies ◽  
Direct Hydrogenation ◽  
Hydrogenation Of Co

AbstractThe selective hydrogenation of CO2 to value-added chemicals is attractive but still challenged by the high-performance catalyst. In this work, we report that gallium nitride (GaN) catalyzes the direct hydrogenation of CO2 to dimethyl ether (DME) with a CO-free selectivity of about 80%. The activity of GaN for the hydrogenation of CO2 is much higher than that for the hydrogenation of CO although the product distribution is very similar. The steady-state and transient experimental results, spectroscopic studies, and density functional theory calculations rigorously reveal that DME is produced as the primary product via the methyl and formate intermediates, which are formed over different planes of GaN with similar activation energies. This essentially differs from the traditional DME synthesis via the methanol intermediate over a hybrid catalyst. The present work offers a different catalyst capable of the direct hydrogenation of CO2 to DME and thus enriches the chemistry for CO2 transformations.

scholarly journals Experimental and Theoretical Studies of Sonically Prepared Cu–Y, Cu–USY and Cu–ZSM-5 Catalysts for SCR deNOx

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 824
Author(s):  
Przemysław J. Jodłowski ◽  
Izabela Czekaj ◽  
Patrycja Stachurska ◽  
Łukasz Kuterasiński ◽  
Lucjan Chmielarz ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Ultrasonic Irradiation ◽  
Active Phase ◽  
Spectroscopic Studies ◽  
In Situ Drifts ◽  
Ft Ir ◽  
Diffuse Reflectance Infrared ◽  
Experimental And Theoretical Studies

The objective of our study was to prepare Y-, USY- and ZSM-5-based catalysts by hydrothermal synthesis, followed by copper active-phase deposition by either conventional ion-exchange or ultrasonic irradiation. The resulting materials were characterized by XRD, BET, SEM, TEM, Raman, UV-Vis, monitoring ammonia and nitrogen oxide sorption by FT-IR and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). XRD data confirmed the purity and structure of the Y/USY or ZSM-5 zeolites. The nitrogen and ammonia sorption results indicated that the materials were highly porous and acidic. The metallic active phase was found in the form of cations in ion-exchanged zeolites and in the form of nanoparticle metal oxides in sonochemically prepared catalysts. The latter showed full activity and high stability in the SCR deNOx reaction. The faujasite-based catalysts were fully active at 200–400 °C, whereas the ZSM-5-based catalysts reached 100% activity at 400–500 °C. Our in situ DRIFTS experiments revealed that Cu–O(NO) and Cu–NH3 were intermediates, also indicating the role of Brønsted sites in the formation of NH4NO3. Furthermore, the results from our experimental in situ spectroscopic studies were compared with DFT models. Overall, our findings suggest two possible mechanisms for the deNOx reaction, depending on the method of catalyst preparation (i.e., conventional ion-exchange vs. ultrasonic irradiation).

The antifungal factors in barley. IV. Isolation, structure, and synthesis of the hordatines

1967 ◽  
Vol 45 (15) ◽  
pp. 1745-1760 ◽  
Author(s):  
A. Stoessl
Keyword(s):  
Oxidative Coupling ◽  
Degradation Products ◽  
Spectroscopic Studies

Careful fractionation of extracts prepared from barley coleoptiles gave small amounts of pure hordatines A and B and substantial amounts of a mixture of their glucosides. The structures of the hordatines were deduced by degradative and spectroscopic studies and by the synthesis of some degradation products. A synthesis of racemic hordatine A analogous to its probable biogenesis was achieved by the oxidative coupling of coumaroylagmatine.The possible role of the hordatines in lignification is briefly discussed.

Experimental Study of the Effect of Precursor Composition On the Microstructure of Gallium Nitride Thin Films Grown by the MOCVD Process

2021 ◽  
Author(s):  
Omar D. Jumaah ◽  
Yogesh Jaluria
Keyword(s):  
Thin Films ◽  
Gallium Nitride ◽  
Chemical Vapor Deposition ◽  
Deposition Rate ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Transport Processes ◽  
Carrier Gas ◽  
Precursor Composition

Abstract Chemical vapor deposition (CVD) is a widely used manufacturing process for obtaining thin films of materials like silicon, silicon carbide, graphene and gallium nitride that are employed in the fabrication of electronic and optical devices. Gallium nitride (GaN) thin films are attractive materials for manufacturing optoelectronic device applications due to their wide band gap and superb optoelectronic performance. The reliability and durability of the devices depend on the quality of the thin films. The metal-organic chemical vapor deposition (MOCVD) process is a common technique used to fabricate high-quality GaN thin films. The deposition rate and uniformity of thin films are determined by the thermal transport processes and chemical reactions occurring in the reactor, and are manipulated by controlling the operating conditions and the reactor geometrical configuration. In this study, the epitaxial growth of GaN thin films on sapphire (AL2O3) substrates is carried out in two commercial MOCVD systems. This paper focuses on the composition of the precursor and the carrier gases, since earlier studies have shown the importance of precursor composition. The results show that the flow rate of trimethylgallium (TMG), which is the main ingredient in the process, has a significant effect on the deposition rate and uniformity of the films. Also the carrier gas plays an important role in deposition rate and uniformity. Thus, the use of an appropriate mixture of hydrogen and nitrogen as the carrier gas can improve the deposition rate and quality of GaN thin films.

Why do zeolites induce an unprecedented electronic state on exchanged metal ions?

2017 ◽  
Vol 19 (36) ◽  
pp. 25105-25114 ◽  
Author(s):  
Akira Oda ◽  
Takahiro Ohkubo ◽  
Takashi Yumura ◽  
Hisayoshi Kobayashi ◽  
Yasushige Kuroda
Keyword(s):  
Metal Ions ◽  
Electronic State ◽  
Base Metal ◽  
Metal Ion ◽  
High Efficiency ◽  
Lewis Base ◽  
Mfi Zeolite ◽  
Adsorption Processes ◽  
Exact Position

Understanding the exact position and the detailed role of the Al array in zeolites is essential for elucidating the origin of unique properties and for designing zeolite materials with high efficiency in catalytic and adsorption processes. In this work, we advanced pivotal roles of Lewis base–metal ion bifunctionality caused by Al atoms arrayed circumferentially in the MFI-zeolite pores.

Elucidating the Key Role of a Lewis Base Solvent in the Formation of Perovskite Films Fabricated from the Lewis Adduct Approach

2017 ◽  
Vol 9 (38) ◽  
pp. 32868-32875 ◽  
Author(s):  
Xiaobing Cao ◽  
Lili Zhi ◽  
Yahui Li ◽  
Fei Fang ◽  
Xian Cui ◽  
...  
Keyword(s):  
Lewis Base ◽  
Lewis Adduct

Tris(pyrazolyl)borate Cobalt-Catalyzed Hydrogenation of C═O, C═C, and C═N Bonds: An Assistant Role of a Lewis Base

2019 ◽  
Vol 21 (8) ◽  
pp. 2693-2698 ◽  
Author(s):  
Yang Lin ◽  
De-Ping Zhu ◽  
Yi-Ran Du ◽  
Rui Zhang ◽  
Suo-Jiang Zhang ◽  
...  
Keyword(s):  
Lewis Base
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