Contact chemical shifts for the hydrogen atoms of nickel complexes of aromatic amines. Spin density distributions in naphthalene and anthracene derivatives. Spin density transmission through carbon, nitrogen, oxygen, and sulfur atoms

1978 ◽  
Vol 82 (10) ◽  
pp. 1175-1180 ◽  
Author(s):  
Scott R. King ◽  
Leon M. Stock
Keyword(s):  
Spin Density ◽  
Aromatic Amines ◽  
Chemical Shifts ◽  
Nickel Complexes ◽  
Hydrogen Atoms ◽  
Density Distributions ◽  
Anthracene Derivatives

Computational Investigation of the Asymmetry in Photosynthetic Reaction Center Models from First Principles

2020 ◽  
Author(s):  
Denis Artiukhin ◽  
Patrick Eschenbach ◽  
Johannes Neugebauer
Keyword(s):  
Spin Density ◽  
Reaction Center ◽  
Density Functional ◽  
Photosynthetic Reaction Center ◽  
Chem Phys ◽  
Molecular Structures ◽  
Error Characteristic ◽  
Molecular Systems ◽  
Density Distributions ◽  
The Asymmetry

We present a computational analysis of the asymmetry in reaction center models of photosystem I, photosystem II, and bacteria from <i>Synechococcus elongatus</i>, <i>Thermococcus vulcanus</i>, and <i>Rhodobacter sphaeroides</i>, respectively. The recently developed FDE-diab methodology [J. Chem. Phys., 148 (2018), 214104] allowed us to effectively avoid the spin-density overdelocalization error characteristic for standard Kohn–Sham Density Functional Theory and to reliably calculate spin-density distributions and electronic couplings for a number of molecular systems ranging from dimeric models in vacuum to large protein including up to about 2000 atoms. The calculated spin densities showed a good agreement with available experimental results and were used to validate reaction center models reported in the literature. We demonstrated that the applied theoretical approach is very sensitive to changes in molecular structures and relative orientation of molecules. This makes FDE-diab a valuable tool for electronic structure calculations of large photosynthetic models effectively complementing the existing experimental techniques.

29Si-Kernresonanzuntersuchungen an N-Trimethylsilyl-substituierten Aminen und Amiden / 29Si Nuclear Magnetic Resonance Studies on N-Trimethylsilyl Derivatives of Amines and Amides

1977 ◽  
Vol 32 (2) ◽  
pp. 163-166 ◽  
Author(s):  
B. Heinz ◽  
H. C. Marsmann ◽  
U. Niemann
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Aromatic Amines ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Electronic Charge ◽  
Magnetic Resonance Studies ◽  
Basic Character ◽  
Silyl Derivatives ◽  
Trimethylsilyl Derivatives ◽  
Derivatives Of

The 29Si chemical shifts of several trimethyl silyl derivatives of amines and amides are measured and compared to other chemical and theoretical properties such as the basicities or the electronic charge on the nitrogen or the hydrogen of the N-H group of the amine or the amide. Whereas the 29Si chemical shift of saturated amines can be rationalized in terms of substituent effects, the shifts of aromatic amines show some dependency on the basic character of the amine. There seems to be little correlation between 29Si chemical shifts and electronic charge, but there is a similarity of 29Si with 1H chemical shifts of the NH group, which is interpreted as depending on anisotropy effects.

Two phosphaalkene radical cations with inverse spin density distributions

2015 ◽  
Vol 44 (34) ◽  
pp. 15099-15102 ◽  
Author(s):  
Xiaobo Pan ◽  
Xingyong Wang ◽  
Zaichao Zhang ◽  
Xinping Wang
Keyword(s):  
Spin Density ◽  
Radical Cations ◽  
Density Distributions ◽  
Weakly Coordinating ◽  
Weakly Coordinating Anion

Two phosphaalkene radical cations have been made by using a weakly coordinating anion, and they exhibit inverse spin density distributions.

Spin-density distributions in meso-alkyl/aryl hybrid porphyrin cation radicals

1988 ◽  
Vol 27 (8) ◽  
pp. 1510-1512 ◽  
Author(s):  
Michael Atamian ◽  
Richard W. Wagner ◽  
Jonathan S. Lindsey ◽  
David F. Bocian
Keyword(s):  
Spin Density ◽  
Alkyl Aryl ◽  
Cation Radicals ◽  
Density Distributions ◽  
Porphyrin Cation

Synthesis and Thermal Property of Poly(Allylamine Hydrochloride)

2010 ◽  
Vol 150-151 ◽  
pp. 1480-1483 ◽  
Author(s):  
Hong Chi Zhao ◽  
Xiu Ting Wu ◽  
Wei Wei Tian ◽  
Shi Tong Ren
Keyword(s):  
Thermal Property ◽  
Chemical Shifts ◽  
Hydrogen Atoms ◽  
Nuclear Magnetic Resonance Spectrometer ◽  
Vibration Absorption ◽  
Thermogravimetric Analyzer ◽  
Stretching Vibration ◽  
Peak Areas ◽  
Infrared Spectrometer ◽  
Allylamine Hydrochloride

Poly(allylamine phosphate) (PAP) was synthesized by solution polymerization using allylamine phosphate (AP) as monomer, 2,2’-azo-bis-2-amidinopropane dihydrochloride (AAP•2HCl) as initiator, respectively. PAP reacted with concentrated hydrochloric acid and it converted into poly(allylamine hydrochloride) (PAH). The effects of varying the concentrations of initiator and monomer on the polymerization conversion were investigated in detail. The chemical structure and thermal property of the polymer were studied by Fourier transform infrared spectrometer (FTIR), nuclear magnetic resonance spectrometer (NMR), thermogravimetric analyzer (TGA), differential scanning calorimeter (DSC), X-ray diffractmeter (XRD), respectively. PAH was prepared because of the disappearance of the stretching vibration absorption peaks and deformation vibration absorption peak of C-H bonds in -C=CH2 at 3020cm-1, 3085cm-1 and 1310cm-1 in the FTIR spectra. The three peak areas and their chemical shifts were consistent with the three kinds of hydrogen atoms in polymer formula in 1H NMR spectrum, which proved that PAH was synthesized. PAH had three decomposing stages and it decomposed completely at 700oC. The glass transition temperature (Tg) of PAH increased with decreasing concentration of initiator. The conversion of monomer increased with the increasing concentrations of initiator and monomer.

Sign in / Sign up

Export Citation Format

Share Document