Charge distributions and chemical effects. XL. Chemical bonds in benzenoid hydrocarbons

1986 ◽  
Vol 64 (2) ◽  
pp. 404-412 ◽  
Author(s):  
S. Fliszár ◽  
G. Cardinal ◽  
N. A. Baykara
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Atomic Charges ◽  
Chemical Bonds ◽  
Benzenoid Hydrocarbons ◽  
Average Deviation ◽  
Chemical Effects ◽  
Local Charge ◽  
Theoretical Results

Benzenoid hydrocarbons were examined using a bond energy scheme featuring the role of atomic charges. The latter were conveniently deduced from appropriate correlations between theoretical results and 13C nuclear magnetic resonance shifts. Atomization energies calculated in this manner agree with their experimental counterparts to within 0.36 kcal mol-1 (average deviation). It appears that benzenoid hydrocarbons can be efficiently described in terms of local charge density properties. In the absence of any distinctive specific feature characterizing benzenoids, this particular description of chemical bonds ultimately results in a unifying genealogy smoothly relating to one another the various possible types of CC and CH bonds which are formed by sp2 and sp3 carbons.

Charge distributions and chemical effects. XXVI. Relationships between nuclear magnetic resonance shifts and atomic charges for 17O nuclei in ethers and carbonyl compounds

1982 ◽  
Vol 60 (2) ◽  
pp. 106-110 ◽  
Author(s):  
Marie-Thérèse Béraldin ◽  
Edouard Vauthier ◽  
Sándor Fliszár
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Oxygen Atom ◽  
Carbonyl Compounds ◽  
Electronic Charge ◽  
Atomic Charges ◽  
Chemical Effects ◽  
Opposite Trend ◽  
Nuclear Magnetic ◽  
Oxygen Atoms

The 17O nuclear magnetic resonance shifts of dialkylethers are linearly related to the electron populations on the oxygen atoms, in a range covering L ~ 130 ppm, showing that any increase of electronic charge at the oxygen atom is accompanied by a downfield nmr shift. The opposite trend is observed for the oxygen atoms of ketones and aldehydes.

Charge distributions and chemical effects. XXX. Relationships between nuclear magnetic resonance shifts and atomic charges

1982 ◽  
Vol 104 (20) ◽  
pp. 5287-5292 ◽  
Author(s):  
Sandor Fliszar ◽  
Guy Cardinal ◽  
Marie Therese Beraldin
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Atomic Charges ◽  
Charge Distributions ◽  
Chemical Effects ◽  
Nuclear Magnetic

scholarly journals Role of Skeletal Muscle Metabolism in Exercise Capacity of Patients With Myocardial Infarction Studied by Phosphorus-31 Nuclear Magnetic Resonance.

1995 ◽  
Vol 59 (6) ◽  
pp. 315-322 ◽  
Author(s):  
Taka'aki Katsuki ◽  
Takanori Yasu ◽  
Nobuhiro Ohmura ◽  
Ikuko Nakada ◽  
Mikihisa Fujii ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Skeletal Muscle ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Exercise Capacity ◽  
Muscle Metabolism ◽  
Skeletal Muscle Metabolism ◽  
Nuclear Magnetic

Recovery of contractility and pHi during respiratory acidosis in ferret hearts: role of Na(+)-H+ exchange

1990 ◽  
Vol 259 (3) ◽  
pp. H843-H848 ◽  
Author(s):  
H. E. Cingolani ◽  
Y. Koretsune ◽  
E. Marban
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Respiratory Acidosis ◽  
Partial Recovery ◽  
Mean Values ◽  
First Derivative ◽  
Cardiac Contractile ◽  
Developed Pressure

During acute respiratory acidosis, cardiac contractile pressure first drops but then recovers substantially. We investigated the mechanism of this response in isovolumic perfused ferret hearts. Developed pressure (DP) and its first derivative (dP/dt) were measured before, during, and after hypercapnia induced by equilibrating the perfusate with 15% CO2, rather than the 5% CO2 used in control. Intramyocardial pH (pHi) was measured by phosphorus nuclear magnetic resonance (NMR) spectroscopy. After the onset of hypercapnia (1-2 min), DP and +dP/dt reached minimal mean values of 37 +/- 2 and 39 +/- 3% of control, respectively. This early decline in myocardial contactility was followed by a partial recovery such that DP and +dP/dt had returned to 66 +/- 6 and 62 +/- 4% of control, respectively, by 14 min of hypercapnia. pHi fell from 7.17 +/- 0.01 in control to 6.88 +/- 0.11 after approximately 2 min of hypercapnia. Thereafter, pHi recovered linearly with a mean slope of 0.011 +/- 0.003 pH U/min. Ethylisopropylamiloride (10(-6) M), a blocker of Na(+)-H+ exchange, prevented the recovery of pHi during hypercapnia and attenuated the recovery of contractility by 40%. We conclude that the recovery of contractility during respiratory acidosis at least partially reflects an underlying recovery of pHi mediated by Na(+)-H+ exchange.

Targeting cancer's Achilles’ heel: role of BCL-2 inhibitors in cellular senescence and apoptosis

2019 ◽  
Vol 11 (17) ◽  
pp. 2287-2312 ◽  
Author(s):  
Aarti Anantram ◽  
Mariam Degani
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Tumor Growth ◽  
Cellular Senescence ◽  
Anticancer Agents ◽  
Anticancer Therapy ◽  
Targeted Chemotherapy ◽  
Structure Based Drug Design ◽  
Selective Targeting

Members of the antiapoptotic BCL-2 proteins are involved in tumor growth, progression and survival, and are also responsible for chemoresistance to conventional anticancer agents. Early efforts to target these proteins yielded some active compounds; however, newer methodologies involving structure-based drug design, Nuclear Magnetic Resonance (NMR)-based screening and fragment-based screening yielded more potent compounds. Discovery of specific as well as nonspecific inhibitors of this class of proteins has resulted in great advances in targeted chemotherapy and decrease in chemoresistance. Here, we review the history and current progress in direct as well as selective targeting of the BCL-2 proteins for anticancer therapy.

The Basis for the Hard-Water Antagonism of Glyphosate Activity

Weed Science ◽  
1995 ◽  
Vol 43 (4) ◽  
pp. 541-548 ◽  
Author(s):  
Kurt D. Thelen ◽  
Evelyn P. Jackson ◽  
Donald Penner
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Ammonium Sulfate ◽  
Hard Water ◽  
Calcium Antagonism ◽  
Chemical Effects ◽  
Spray Solution ◽  
Type Complex ◽  
Over Time ◽  
Nuclear Magnetic

Hard-water cations, such as Ca+2and Mg+2, present in the spray solution can greatly reduce the efficacy of glyphosate. These cations potentially compete with the isopropylamine in the formulation for association with the glyphosate anion.14C-Glyphosate absorption by sunflower was reduced in the presence of Ca+2. The addition of ammonium sulfate overcame the observed decrease in14C-glyphosate absorption. Nuclear Magnetic Resonance (NMR) was used to study the chemical effects of calcium and calcium plus ammonium sulfate (AMS) on the glyphosate molecule. Data indicate an association of calcium with both the carboxyl and phosphonate groups on the glyphosate molecule. Initially, a random association of the compounds occurred; however, the reaction progressed to yield a more structured, chelate type complex over time. NH4+from AMS effectively competed with calcium for complexation sites on the glyphosate molecule. Data suggest that the observed calcium antagonism of glyphosate and AMS reversal of the antagonism are chemically based.

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