Results 111 to 120 of about 57,191 (159)

Chemometric Analysis of Substituent Effects. VII. Inductive Effect as a Basic Substituent Effect. Isoeffect Substituent Constant

Collection of Czechoslovak Chemical Communications, 1995
The paper deals with chemometric analysis of the inductive effect. The notion of inductive effect is discussed, and unambiguous definitions are given for the notions of triad: reaction centre-basic skeleton-substituent, and the therewith connected definitions of inductive effect.
Oldřich Pytela, Aleš Halama
openaire   +1 more source

Substituent effects. 4. Nature of substituent effects at carbonyl groups

Journal of the American Chemical Society, 1992
The effect of substituents on the properties of acyl derivatives has been examined. Geometry optimizations were carried out at the MP2/6-31G * theoretical level, followed by calculation of energies at the MP3/6-311++G ** level. The energies were studied via isodamic reactions with ethane leading to acetone and a methyl derivative.
Kenneth B. Wiberg, Christopher M. Hadad, Paul R. Rablen, Jerzy Cioslowski   +3 more
openaire   +1 more source

THE EFFECT OF SUBSTITUENTS ON PHTHALOCYANINE PHOTOCYTOTOXICITY

Photochemistry and Photobiology, 1987
AbstractPhthalocyanine (Pc) dyes are a class of photosensitizers that are being considered for use in the photodynamic therapy of cancer. A final choice for the most useful drug demands phototoxicity screening of various structurally related Pc dyes, such as those with different substituents at the peripheral benzene rings.
I, Rosenthal, E, Ben-Hur, S, Greenberg, A, Concepcion-Lam, D M, Drew, C C, Leznoff   +5 more
openaire   +2 more sources

Substituent Effects on Folding in Cyclotetraphosphane

Chemische Berichte, 1991
Ab initio quantum chemical calculations evidence a very flat potential hypersurface for folding of parent cyclotetraphosphane. This is in accord with a corresponding vibrational analysis. Electronegative substituents increase folding of the fourmembered ring system.
Schoeller, Wolfgang, BUSCH, T
openaire   +2 more sources

Ligand substituents effect on 10Dq

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2012
Reaction of 5,6-dihydro-5,6-epoxy-1,10-phenanthroline (L) with Ni(ClO(4))(2)·6H(2)O in methanol in 3:1M proportion at room temperature yields [NiL(3)](ClO(4))(2)·2H(2)O. The X-ray crystal structure of the cation NiL(3)(2+) has been determined. Aminolysis of the three epoxide rings in NiL(3)(2+) by 4-substituted anilines in boiling water without any ...
Nirmal K, Shee, Michael G B, Drew, Dipankar, Datta   +2 more
openaire   +2 more sources

The Substituent Effect. 15. The LSFE Treatment of Substituent Effects on Basicities of Pyridines

Bulletin of the Chemical Society of Japan, 1980
Abstract The relative dissociation constants of meta and para substituted pyridinium ions in H2O at 25 °C were collected from a number of sources. To understand the actual substituent effects with a combination of inductive (I) and pi-electronic (Pi) effect components, the LSFE equation has been employed statistically for each of the ...
Masami Sawada, Masaharu Ichihara, Yasuhide Yukawa, Takeshi Nakachi, Yuho Tsuno   +4 more
openaire   +1 more source

Substituent Effects on the Cooperativity of Halogen Bonding

The Journal of Physical Chemistry A, 2013
DFT calculations (B97-1) with the 6-31+G(d,p)-LanL2DZdp basis set were used to analyze the intermolecular interactions in 4-Z-Py···XCN···XCN triads (Z = H, F, OH, OCH3, CH3, NH2, NO2, and CN; Py = pyridine; and X = Cl and Br) that are connected by halogen-bond interactions. To understand the properties of the systems better, the corresponding dyads are
Solimannejad, Mohammad, Malekani, M., Alkorta, Ibon   +2 more
openaire   +3 more sources

Substituent effects of halopyridines

Journal of Molecular Structure, 2008
Abstract The electronic structures of a number of halopyridines were measured by HeI photoelectron (PE) spectroscopy. Combined the empirical arguments and theoretical methods, the observed PE bands were interpreted. The careful analysis of measured π-orbital and halogen lone pair ionization energies enable us to describe substituent effects in terms ...
Chun-Ping Ma, Li Yao, Mao-Fa Ge
openaire   +1 more source

Substituent effects in cyclopolyphosphines

Journal of the Chemical Society, Chemical Communications, 1974
For cyclopolyphosphines, (RP)n, a linear relationship which is independent of the ring size, n, exists between the electrochemical reduction potential of the ring and the inductive effect of the pendant organic group.
Timothy J. DuPont, Lawrence R. Smith, Jerry L. Mills   +2 more
openaire   +1 more source

Additive Effects of Substituents

Nature, 1950
THE present practice of analysing data relating to reaction-rates in solution in terms of the parameters of the modified Arrhenius equation, has led to a more complete understanding of the way in which polar substituents affect chemical reactivity by focusing attention on the fact
BRYNMOR JONES, J. ROBINSON
openaire   +1 more source