Factors Influencing Anion Binding Stoichiometry: The Subtle Influence of Electronic Effects

2008 ◽  
Vol 2008 (9) ◽  
pp. 1559-1567 ◽  
Author(s):  
Adam J. Lowe ◽  
Gail A. Dyson ◽  
Frederick M. Pfeffer
Keyword(s):  
Anion Binding ◽  
Electronic Effects ◽  
Binding Stoichiometry ◽  
Factors Influencing

Factors Promoting Alkene Migratory Insertion into Metal-Nitrogen Bond during Hydroamination in Recent Studies

2021 ◽  
Vol 18 ◽  
Author(s):  
Wenlai Han
Keyword(s):  
Transition Metal ◽  
Late Transition Metal ◽  
Electronic Effects ◽  
Metal Centers ◽  
Unsaturated Bond ◽  
Factors Influencing ◽  
Migratory Insertion ◽  
Late Transition ◽  
Metal Catalyzed ◽  
Nitrogen Bond

: Migratory insertion is a fundamental organometallic transformation that enables the functionalization of an unsaturated bond. Recent reports on catalytic hydroamination provide evidence that supports an intermolecular migratory insertion pathway featuring alkene insertion into metal-nitrogen (M-N) bonds. This article presents factors influencing the rate of migratory insertion in late-transition metal-catalyzed hydroamination, including steric and electronic effects from ligands, alkenes, and metal centers, along with stabilization from coordinated amine intermediates and ordered transition states.

Benzoannelated quinone methides

1982 ◽  
Vol 47 (6) ◽  
pp. 1645-1653 ◽  
Author(s):  
Bohumír Koutek ◽  
Milena Píšová ◽  
Josef Krupička ◽  
Antonín Lyčka ◽  
Dobroslav Šnobl ◽  
...  
Keyword(s):  
Ground State ◽  
Charge Separation ◽  
Side Chain ◽  
Exocyclic Double Bond ◽  
Electronic Effects ◽  
Quinone Methides ◽  
Factors Influencing ◽  
Nmr Data ◽  
State Charge ◽  
C Nmr

On the basis of detailed study of UV, IR, 13C NMR and E1/2 data of quinone methides V-VII three dominant factors influencing the behaviour of benzoannelated compounds must be considered: 1) electronic effects of both the exocyclic carbon substituents and the fused rings, 2) the extent to which the substituents are displaced out of the plane of the exocyclic double bond through steric interference between the side-chain substituents and peri-hydrogens and 3) the extent of the angular distorsion of the quinone-like rings. The ground state charge separation (~0.2e) in nonannelated derivatives was found to be strongly minimized by annelation of two benzene units to the parent systems. Near parallelism with this phenomenon was also observed in both the carbonyl vibration frequency and 13C NMR data.

New Triazole-Containing Branched Bis(dipeptidomimetic) – Switching from Self-Dimerization to Anion-Binding Properties

Synlett ◽  
2017 ◽  
Vol 28 (20) ◽  
pp. 2807-2811 ◽  
Author(s):  
Tin-Ki Chui ◽  
Hak-Fun Chow
Keyword(s):  
Anion Binding ◽  
Vapor Pressure Osmometry ◽  
Binding Affinities ◽  
Structural Studies ◽  
Nmr Studies ◽  
Binding Properties ◽  
Nmr Titration ◽  
Binding Stoichiometry ◽  
Plot Analysis ◽  
Diethyl Phosphate

A triazole-containing branched bis(dipeptidomimetic) 2 using l-lysine as a flexible branching unit was synthesized and characterized. The compound was found to form weak dimers (K dim = 19 M–1) in chloroform as shown by vapor pressure osmometry (VPO) and concentration-dependent 1H NMR studies. On the other hand, the compound was capable of binding chloride and monobasic diethyl phosphate (DEP) in chloroform. Job plot analysis, MALDI-TOF mass spectrometry, and NMR titration studies revealed a 1:1 binding stoichiometry with good binding affinities (K a ≈ 640–780 M–1). Structural studies using ­ROESY NMR spectroscopy and molecular modelling on the 2–DEP complex indicated the adoption of a helix-like conformation by the host with the guest situated near the branching juncture.

scholarly journals Alkene selenenylation: A comprehensive analysis of relative reactivities, stereochemistry and asymmetric induction, and their comparisons with sulfenylation

2011 ◽  
Vol 7 ◽  
pp. 744-758 ◽  
Author(s):  
Vadim A Soloshonok ◽  
Donna J Nelson
Keyword(s):  
Double Bond ◽  
Theoretical Data ◽  
Comprehensive Analysis ◽  
Asymmetric Induction ◽  
Steric Effects ◽  
Addition Reactions ◽  
Electronic Effects ◽  
Broad Perspective ◽  
Factors Influencing ◽  
Electronic And Steric Effects

A broad perspective of various factors influencing alkene selenenylation has been developed by concurrent detailed analysis of key experimental and theoretical data, such as asymmetric induction, stereochemistry, relative reactivities, and comparison with that of alkene sulfenylation. Alkyl group branching α to the double bond was shown to have the greatest effect on alkene reactivity and the stereochemical outcome of corresponding addition reactions. This is in sharp contrast with other additions to alkenes, which depend more on the degree of substitution on C=C or upon substituent electronic effects. Electronic and steric effects influencing asymmetric induction, stereochemistry, regiochemistry, and relative reactivities in the addition of PhSeOTf to alkenes are compared and contrasted with those of PhSCl.

Factors influencing adhesive bonding at the bone/implant interface

1992 ◽  
Vol 50 (2) ◽  
pp. 1114-1115
Author(s):  
Julie A. Martini ◽  
Robert H. Doremus
Keyword(s):  
Electron Microscopy ◽  
Adhesive Bonding ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Bone Implant ◽  
Factors Influencing ◽  
Lr White ◽  
Transmission Electron ◽  
New Zealand White Rabbits ◽  
Scanning Electron

Tracy and Doremus have demonstrated chemical bonding between bone and hydroxylapatite with transmission electron microscopy. Now researchers ponder how to improve upon this bond in turn improving the life expectancy and biocompatibility of implantable orthopedic devices.This report focuses on a study of the- chemical influences on the interfacial integrity and strength. Pure hydroxylapatite (HAP), magnesium doped HAP, strontium doped HAP, bioglass and medical grade titanium cylinders were implanted into the tibial cortices of New Zealand white rabbits. After 12 weeks, the implants were retrieved for a scanning electron microscopy study coupled with energy dispersive spectroscopy.Following sacrifice and careful retrieval, the samples were dehydrated through a graduated series starting with 50% ethanol and continuing through 60, 70, 80, 90, 95, and 100% ethanol over a period of two days. The samples were embedded in LR White. Again a graduated series was used with solutions of 50, 75 and 100% LR White diluted in ethanol.

Factors Influencing Electrophysiologic Responsivity in Normal Adults

1965 ◽  
Vol 8 (4) ◽  
pp. 323-347
Author(s):  
Robert Goldstein ◽  
Benjamin RosenblÜt
Keyword(s):  
Conditioned Stimulus ◽  
White Light ◽  
Pure Tone ◽  
Alpha Rhythm ◽  
White Women ◽  
White Men ◽  
Inverse Relation ◽  
Factors Influencing ◽  
Electrodermal Responses ◽  
Normal Adults

Electrodermal and electroencephalic responsivity to sound and to light was studied in 96 normal-hearing adults in three separate sessions. The subjects were subdivided into equal groups of white men, white women, colored men, and colored women. A 1 000 cps pure tone was the conditioned stimulus in two sessions and white light was used in a third session. Heat was the unconditioned stimulus in all sessions. Previously, an inverse relation had been found in white men between the prominence of alpha rhythm in the EEG and the ease with which electrodermal responses could be elicited. This relation did not hold true for white women. The main purpose of the present study was to answer the following questions: (1) are the previous findings on white subjects applicable to colored subjects? (2) are subjects who are most (or least) responsive electrophysiologically on one day equally responsive (or unresponsive) on another day? and (3) are subjects who are most (or least) responsive to sound equally responsive (or unresponsive) to light? In general, each question was answered affirmatively. Other factors influencing responsivity were also studied.

Factors Influencing Pressure in the Portal Vein as Studied in the Intact Animal

1950 ◽  
Vol 16 (1) ◽  
pp. 194-210 ◽  
Author(s):  
Frederick W. Hoffbauer ◽  
Jesse L. Bollman ◽  
John L. Grindlay
Keyword(s):  
Portal Vein ◽  
Intact Animal ◽  
Factors Influencing
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