Topic
Steric effects
About: Steric effects is a research topic. Over the lifetime, 16112 publications have been published within this topic receiving 319615 citations. The topic is also known as: steric hindrance.
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TL;DR: The participation of the different thiol groups in disulfide bonds appeared to depend on their location in the native structure, with surface-located cysteines more involved than internally located ones and fewer native-location bonds observed.
Abstract: Intermolecular disulfide bond formation in pure ‚-lactoglobulin (‚-Lg) B and in its 1:1 mixture with R-lactalbumin (R-La), heated at 85 °C for 10 min in solutions of low and high (100 mM NaCl) ionic strength and pH 6.0, was studied by reverse-phase HPLC and MALDI-TOF mass spectrometry. Disulfide bonding between ‚-Lg monomers was more extensive than reported in the literature for a temperature of 68.5 °C, including formation of trimers connected by two of the three adjacent cysteines, C106/C119/C121. The participation of the different thiol groups in disulfide bonds appeared to depend on their location in the native structure, with surface-located cysteines more involved than internally located ones. This also applied to R-La-‚-Lg interactions, where the predominant participants were the surface-located RC111, RC120, RC61, and RC6. The least active participant was RC28, suggesting that it becomes sterically inaccessible during unfolding of the protein. High ionic strength apparently promoted disulfide bonding. The order of cysteine participation at the high ionic strength was similar to that at low ionic strength, with fewer native-location bonds observed and a lower activity of some groups, such as ‚-C106/C119/C121 and RC61.
67 citations
TL;DR: Recent research has shown that 7-azaindolyl and derivatives are excellent blue emitters for organic light emitting diodes, they have rich coordination chemistry with both main group elements and transition metal ions, and their metal complexes display not only phosphorescence but also unusual and often unprecedented reactivity toward C-H and C-X bonds
Abstract: 7-Azaindole and its derivatives have been extensively investigated for uses in biological probes and imaging In contrast, there have been very limited studies on the coordination chemistry and the applications of 7-azaindole and derivatives in materials science and in chemical bond activation Our recent research has shown that 7-azaindolyl and derivatives are excellent blue emitters for organic light emitting diodes, they have rich coordination chemistry with both main group elements and transition metal ions, and their metal complexes display not only phosphorescence but also unusual and often unprecedented reactivity toward C–H and C–X bonds This critical review discusses recent advances in these fields with focuses on new 7-azaindolyl derivatives and their metal complexes developed by our group The luminescent properties and applications of 7-azaindolyl-based compounds will be presented The reactivity of Pt(II) complexes toward C–H and C–X bonds, especially the steric impact of the bis(7-azaindolyl) chelate ligands and bimetallic cooperativity will be discussed (86 references)
67 citations
TL;DR: In this paper, a series of complexes with steric bulk incorporated into the m-S-to-S linker was synthesized and the compounds were analyzed by infrared spectroscopy and cyclic voltammetry.
67 citations
TL;DR: In this article, the aldol reaction of enantiopure N-(haloacetyl)-2-oxazolidinone enolates with aromatic aldehydes was studied for conditions that would induce the reaction to yield predominantly anti adducts.
Abstract: The aldol reaction of enantiopure N-(haloacetyl)-2-oxazolidinone enolates with aromatic aldehydes was studied for conditions that would induce the reaction to yield predominantly anti adducts. It was found herein that the inherent steric and stereoelectronic properties of the aldehyde (R), as well as its chelative ability with the enolate countercation, are crucial in determining which of its enantiotopic faces reacts. Certain metallic enolates (Sn, IV Zn, and Li) are postulated to react through a three-point coordination transition state to yield mainly anti adducts, while others (Sn, II B, Ti) are shown to react via noncoordinated transition states to yield either syn or anti adducts
67 citations
TL;DR: Frustrated Lewis pairs, comprised of combinations of sterically encumbered phosphine (or amine) Lewis bases with boron Lewis acids containing the strongly electron withdrawing bulky pentafluorophenyl substituents, show very remarkable reaction behaviour.
67 citations