scholarly journals Alcohol Oxidation Assisted by Molybdenum Hydrazonato Catalysts Employing Hydroperoxide Oxidants

Catalysts ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 881
Author(s):  
Josipa Mihalinec ◽  
Matea Pajski ◽  
Pascal Guillo ◽  
Mirna Mandarić ◽  
Nikol Bebić ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Infrared Spectroscopy ◽  
Thermogravimetric Analysis ◽  
Magnetic Resonance ◽  
Alcohol Oxidation ◽  
Polynuclear Complexes ◽  
Oxidation Reactions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mononuclear Complexes

Molybdenum(VI) catalysts were obtained from methanol or acetonitrile by the reaction of [MoO2(C5H7O2)2] and isonicotinoyl- or nicotinoyl-based aroylhydrazones. Reactions in methanol resulted in the formation of the mononuclear complexes [MoO2(L1–4)(MeOH)] (1a–4a), while the ones in acetonitrile provided polynuclear complexes [MoO2(L1–4)]n (1–4). Crystals of polynuclear compound, [MoO2(L3)]n∙H2O (3∙H2O), suitable for X-ray diffraction analysis were obtained by the solvothermal procedure at 110 °C. Complexes were characterized by infrared spectroscopy (IR-ATR), nuclear magnetic resonance (NMR), elemental analysis (EA), and thermogravimetric analysis (TGA). The prepared catalysts were tested in alcohol oxidation reactions. Carveol, cyclohexanol, and butan-2-ol were investigated substrates. Because the alcohol oxidations are very challenging due to various possible pathways, the idea was to test different oxidants, H2O2, TBHP in water and decane, to optimize the researched catalytic system.

Tautomerism of bis(2-benzothiazolyl)methanes

1988 ◽  
Vol 66 (6) ◽  
pp. 1467-1473 ◽  
Author(s):  
Carmen Avendaño ◽  
María Teresa Ramos ◽  
José Elguero ◽  
María Luisa Jimeno ◽  
Juana Bellanato ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Infrared Spectroscopy ◽  
Magnetic Resonance ◽  
Diffraction Analysis ◽  
X Ray Diffraction ◽  
Methyl Derivative ◽  
Model Compounds ◽  
X Ray ◽  
Nuclear Magnetic

Tautomerism of dibenzothiazolylmethane (1) and its C-methyl derivative (2) has been studied by 1H nuclear magnetic resonance, ultraviolet, and infrared spectroscopy using C,C-dimethyl (3) and N-methyl (4) derivatives as model compounds of the "CH" and "NH" forms, respectively. X-ray diffraction analysis of the "fixed" N-methyl derivative 4 shows that it corresponds to the Z-sE isomer 4b2. The CH tautomers are unstable in solution and they slowly isomerize into a mixture of NH tautomers that depends on the solvent and on the C-substituent (H or CH3).

scholarly journals Valorization of Byproducts of Hemp Multipurpose Crop: Short Non-Aligned Bast Fibers as a Source of Nanocellulose

Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 4723
Author(s):  
Sara Dalle Vacche ◽  
Vijayaletchumy Karunakaran ◽  
Alessia Patrucco ◽  
Marina Zoccola ◽  
Loreleï Douard ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Thermogravimetric Analysis ◽  
Cannabis Sativa ◽  
Crystallinity Index ◽  
Residual Lignin ◽  
Chemical Pretreatment ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bast Fibers ◽  
Seed Maturity

Nanocellulose was extracted from short bast fibers, from hemp (Cannabis sativa L.) plants harvested at seed maturity, non-retted, and mechanically decorticated in a defibering apparatus, giving non-aligned fibers. A chemical pretreatment with NaOH and HCl allowed the removal of most of the non-cellulosic components of the fibers. No bleaching was performed. The chemically pretreated fibers were then refined in a beater and treated with a cellulase enzyme, followed by mechanical defibrillation in an ultrafine friction grinder. The fibers were characterized by microscopy, infrared spectroscopy, thermogravimetric analysis and X-ray diffraction after each step of the process to understand the evolution of their morphology and composition. The obtained nanocellulose suspension was composed of short nanofibrils with widths of 5–12 nm, stacks of nanofibrils with widths of 20–200 nm, and some larger fibers. The crystallinity index was found to increase from 74% for the raw fibers to 80% for the nanocellulose. The nanocellulose retained a yellowish color, indicating the presence of some residual lignin. The properties of the nanopaper prepared with the hemp nanocellulose were similar to those of nanopapers prepared with wood pulp-derived rod-like nanofibrils.

scholarly journals Coordination Assemblies of Zn(II) Coordination Polymers: Positional Isomeric Effect and Optical Properties

Crystals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 664 ◽  
Author(s):  
Chang-Jie Liu ◽  
Tong-Tong Zhang ◽  
Wei-Dong Li ◽  
Yuan-Yuan Wang ◽  
Shui-Sheng Chen
Keyword(s):  
Optical Properties ◽  
Infrared Spectroscopy ◽  
Thermogravimetric Analysis ◽  
Quantum Yield ◽  
Coordination Polymers ◽  
Square Lattice ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mixed Ligands ◽  
Isomeric Effect

Two Zn(II) coordination polymers (CPs) [Zn(L)(pphda)] (1) and [Zn(L)(ophda)]·H2O (2) were prepared by reactions of ZnSO4·7H2O based on the N-donor 1,4-di(1H-imidazol-4-yl)benzene (L) ligand and two flexible carboxylic acids isomers of 1,4-phenylenediacetic acid (H2pphda) and 1,2-phenylenediacetic acid (H2ophda) as mixed ligands, respectively. Structures of CPs 1 and 2 were characterized by elemental analysis, Infrared spectroscopy (IR), thermogravimetric analysis and single-crystal X-ray diffraction. The CP 1 is a fourfold interpenetrating 66-diamond (dia) architecture, while 2 is a 2D (4, 4) square lattice (sql) layer based on the Zn2(cis-1,2-ophda2−)2 binuclear Zn(II) subunits. The luminescent property, including luminescence lifetime and quantum yield (QY), have been investigated for CPs 1 and 2.

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