Unsaturated Rh(I) and Rh(III) Naphthyl-Based PCP Complexes. Major Steric Effect on Reactivity

2009 ◽  
Vol 28 (6) ◽  
pp. 1900-1908 ◽  
Author(s):  
Christian M. Frech ◽  
Linda J. W. Shimon ◽  
David Milstein
Keyword(s):  
Steric Effect ◽  
Pcp Complexes

scholarly journals Differential steric effects in the inelastic scattering of NO(X) + Ar: spin–orbit changing transitions

2019 ◽  
Vol 21 (26) ◽  
pp. 14173-14185 ◽  
Author(s):  
M. Brouard ◽  
S. D. S. Gordon ◽  
B. Nichols ◽  
V. Walpole ◽  
F. J. Aoiz ◽  
...  
Keyword(s):  
Inelastic Scattering ◽  
Steric Effect ◽  
Steric Effects ◽  
Spin Orbit ◽  
First Time

The differential steric effect for spin–orbit changing collisions of NO with Ar is determined for the first time.

scholarly journals Spatiotemporally programmable cascade hybridization of hairpin DNA in polymeric nanoframework for precise siRNA delivery

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Feng Li ◽  
Wenting Yu ◽  
Jiaojiao Zhang ◽  
Yuhang Dong ◽  
Xiaohui Ding ◽  
...  
Keyword(s):  
Steric Effect ◽  
Sirna Delivery ◽  
Dna Nanotechnology ◽  
Hybridization Chain Reaction ◽  
Dna Nanostructures ◽  
Chain Reaction ◽  
Dna Hairpins ◽  
In Vivo Experiments ◽  
Dna And Rna

AbstractDNA nanostructures have been demonstrated as promising carriers for gene delivery. In the carrier design, spatiotemporally programmable assembly of DNA under nanoconfinement is important but has proven highly challenging due to the complexity–scalability–error of DNA. Herein, a DNA nanotechnology-based strategy via the cascade hybridization chain reaction (HCR) of DNA hairpins in polymeric nanoframework has been developed to achieve spatiotemporally programmable assembly of DNA under nanoconfinement for precise siRNA delivery. The nanoframework is prepared via precipitation polymerization with Acrydite-DNA as cross-linker. The potential energy stored in the loops of DNA hairpins can overcome the steric effect in the nanoframework, which can help initiate cascade HCR of DNA hairpins and achieve efficient siRNA loading. The designer tethering sequence between DNA and RNA guarantees a triphosadenine triggered siRNA release specifically in cellular cytoplasm. Nanoframework provides stability and ease of functionalization, which helps address the complexity–scalability–error of DNA. It is exemplified that the phenylboronate installation on nanoframework enhanced cellular uptake and smoothed the lysosomal escape. Cellular results show that the siRNA loaded nanoframework down-regulated the levels of relevant mRNA and protein. In vivo experiments show significant therapeutic efficacy of using siPLK1 loaded nanoframework to suppress tumor growth.

scholarly journals Steric Effect in Base-catalyzed Ring-opening Reactions of Epoxides

1963 ◽  
Vol 66 (3) ◽  
pp. 355-357 ◽  
Author(s):  
Shizuyoshi Sakai ◽  
Tatsuo Sugiyama ◽  
Yoshio Ishii
Keyword(s):  
Ring Opening ◽  
Steric Effect ◽  
Ring Opening Reactions

The nature of the steric effect in the general-acid-catalyzed hydrolyses of benzaldehyde acetals

1983 ◽  
Vol 48 (23) ◽  
pp. 4175-4179 ◽  
Author(s):  
James L. Jensen ◽  
Anna B. Martinez ◽  
Cheryl L. Shimazu
Keyword(s):  
Steric Effect ◽  
General Acid ◽  
Acid Catalyzed

Abiotic Reactivity of De Novo Designed Artificial Copper Peptides (ArCuPs): The Case of C-H Activation

2022 ◽  
Author(s):  
Divyansh Prakash ◽  
Suchitra Mitra ◽  
Morgan Murphy ◽  
Saumen Chakraborty
Keyword(s):  
Steric Effect ◽  
De Novo ◽  
Outer Sphere ◽  
The Other ◽  
Easy Access ◽  
Oxygen Species ◽  
Redox Potentials ◽  
Spectroscopic Feature ◽  
Detailed Assessment ◽  
Active Variant

We report a series of de novo designed Artificial Cu Peptides (ArCuPs) that oxidize and peroxygenate C-H bonds of model abiotic substrates via electrochemically generated Cu-oxygen species using H2O2 as the terminal oxidant, akin to native Cu enzymes. Detailed assessment of kinetic parameters established the catalytic nature of the ArCuPs. Selective alteration of outer sphere steric at the d layers above and below the Cu site allows facilitated access of substrates, where a more pronounced effect on catalysis is observed when space is created at the d layer below the Cu site via Ile to Ala mutation producing a kcat of 6.2 s-1, TONmax of 14800 and catalytic proficiency (kcat/KM/kuncat) of 340 M-1 for the oxidation of benzyl alcohol. Independent spectroscopic studied revealed that the rate of formation of the Cu-oxygen species and the spectroscopic feature of the most active variant is distinct compared to the other ArCuPs. Systematic alteration of outer sphere hydrophobicity led to a correlated tuning of the T2 Cu site redox potentials by ~80 mV. The enhanced activity of the ArCuP variant is attributed to a combination of steric effect that allows easy access of substrates, the nature of Cu-oxygen species, and stability of this construct compared to others, where Ile to Ala mutation unexpectedly leads to a higher thermostability which is further augmented by Cu binding.

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