نتایج جستجو برای: dynamic nmr
تعداد نتایج: 462263 فیلتر نتایج به سال:
Magnetic iron oxide nanoparticles were synthesized and stabilized inside phospholipid vesicles by two different methods. The resulting magnetoliposome suspensions were characterized by dynamic light scattering and NMR. The NMR analysis demonstrated conclusively that the magnetic cores of the magnetoliposomes contained clusters of smaller, superparamagnetic primary particles. The application of ...
Synthesis of the Guanidium-Meldrum acid zwitterionic salts was developed through a three component reaction of 2, 2-dimethyl-1, 3-dioxane-4, 6-dione (Meldrum acid), aromatic aldehydes and N, N, N’, N’-Tetramethyl-guanidine in benzen at room temperature. These reaction conditions allow the preparation of stable zwitterionic salts in good yields. A dynamic NMR effect is observed as a result of re...
We report the observation of nuclear magnetic resonance (NMR) in a ferromagnet-semiconductor heterostructure in the presence of a spin-polarized current. Spin-polarized electrons injected from a metallic ferromagnet generate a large nuclear spin population in a GaAs quantum well by dynamic polarization. The characteristic time for the polarization process is approximately 20 sec, and the nuclea...
Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy (DNP SENS) is an effective method to significantly improve solid-state NMR investigation of solid surfaces. The presence of unpaired electrons (polarizing agents) is crucial for DNP, but it has drawbacks such as leading to faster nuclear spin relaxation, or even reaction with the substrate under investigation. The latter can be a pa...
Poly (Dimethyl siloxane) thin films were prepared by solvent evaporation method in porous alumina hosts. The thickness of these layers ranged from multilayer to sub-monolayer. Different NMR methods (FFC relaxometry, transverse relaxation, H Double quantum NMR) were applied to study the dynamics and order in these thin films. We found that dynamic restrictions and order increased with decreasing...
in this study, the drug atenolol on c60 fullerene were the drug and its derivatives were optimized fullerene. nbo and nmr for complex computations required in the hf/6-31g (d) and b3lyp/6-31g (d) quantum chemistry method was used. mechanical quantum calculations in theory level of b3lyp/6-31g were performed on structure of atenolol and nano fullerene atenolol with different positions of linking...
A novel approach to the determination of structure and potential dynamics in the solid-state NMR spectroscopy of half-integer quadrupolar nuclei is proposed and demonstrated. The new experiment combines into a single three-dimensional sequence, 2D multiple-quantum magic-angle-spinning NMR and 2D exchange NMR protocols. The result separates for each inequivalent chemical site its spin-diffusion ...
We demonstrated here a facile and efficient synthesis of polyhedral oligomeric silsesquioxane-based amphiphilic polymer by thiol-ene click chemistry. The properties of polyhedral oligomeric silsesquioxane (POSS)–PEG amphiphilic polymers were studied in detail by a combination of 1H NMR, 13C NMR, 29Si NMR FT-IR, GPC, and TG analysis. The newly-designed thiol-ene protocol obtains only anti-Markov...
I& ABSTRACT (Mnu/vm 290 word) As outlined in the original proposal our work deals with NMR and laser Raman scattering experiments on highly viscous liquids, including lubricants, both in bulk and confined geometries, over a wide range of pressures and temperatures. In a general sense we focus on the relationship between molecular level properties as obtained from our experiments and the macrosc...
The self-assembly of the o-carborane-based, bisterpyridyl monomer, 1,2-bis[4'-(4-ethynylphenyl)-2,2':6',2''-terpyridine]-o-carborane, utilizing either Zn(II) or Fe(II) in a precise metal : ligand ratio (1 : 1), generated a family of metallomacrocycles that were studied via ESI-TWIM-MS, (1)H NMR, and 2D NMR (COSY, NOESY). Under kinetic control, via formation of Fe(II) complexes, the main cyclic ...
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