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相关概念视频

Polyprotic Acids03:38

Polyprotic Acids

Acids are classified by the number of protons per molecule that they can give up in a reaction. Acids such as HCl, HNO3, and HCN that contain one ionizable hydrogen atom in each molecule are called monoprotic acids. Their reactions with water are:
Titration of a Polyprotic Acid02:08

Titration of a Polyprotic Acid

A polyprotic acid contains more than one ionizable hydrogen and undergoes a stepwise ionization process. If the acid dissociation constants of the ionizable protons differ sufficiently from each other, then the titration curve for such polyprotic acid generates a distinct equivalence point for each of its ionizable hydrogens. Therefore, titration of a diprotic acid results in the formation of two equivalence points, whereas the titration of a triprotic acid results in the formation of three...
ATP Driven Pumps I: An Overview01:27

ATP Driven Pumps I: An Overview

ATP-driven pumps, also known as transport ATPases, are integral membrane proteins. They have binding sites for ATP located on the membrane's cytosolic side and the ion-conducting domain in the transmembrane region. These pumps use the free energy released from ATP hydrolysis to move the solutes across cell membranes against an electrochemical gradient.
There are four main types of ATP-driven pumps - P-type, V-type, F-type, and ABC transporter. All these pumps are of varying complexities and are...
ATP Driven Pumps II: P-type Pumps01:34

ATP Driven Pumps II: P-type Pumps

The P-type pumps are a large family of integral membrane transporter ATPases. They are divided into five major types based on substrate specificity, from I to V.
A typical P-type pump has three cytosolic domains: nucleotide-binding (N), phosphorylation (P), and activator (A) domains. These domains are connected to the membrane-spanning helices by short amino acid segments. ATP hydrolysis and covalent phosphoenzyme intermediate formation are crucial parts of the catalytic cycle. At the highly...
Insensitive Nuclei Enhanced by Polarization Transfer (INEPT)01:15

Insensitive Nuclei Enhanced by Polarization Transfer (INEPT)

Insensitive Nuclei Enhanced by Polarization Transfer (INEPT) is an advanced Nuclear Magnetic Resonance (NMR) technique specifically designed to detect and enhance the signals of low-abundance nuclei, such as carbon-13 and nitrogen-15, in small molecules. The fundamental principle behind INEPT is the transfer of polarization from a more abundant and highly polarizable nucleus, typically hydrogen-1, to the low-abundance nucleus of interest. This process effectively boosts the NMR signal of the...
Titration of Polyprotic Acids with a Strong Base01:23

Titration of Polyprotic Acids with a Strong Base

Titration of a polyprotic acid, which contains multiple ionizable protons, involves distinct dissociation steps, each with its own dissociation constant (Ka). Each successive Ka is weaker than the previous one. In the titration of a polyprotic acid like sulfurous acid with a strong base such as sodium hydroxide, the base first neutralizes the initial ionizable proton, forming an intermediate species (e.g., hydrogen sulfite ions). This step's titration curve resembles that of a weak monoprotic...

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相关实验视频

Updated: Jul 16, 2026

Reductive Electropolymerization of a Vinyl-containing Poly-pyridyl Complex on Glassy Carbon and Fluorine-doped Tin Oxide Electrodes
09:17

Reductive Electropolymerization of a Vinyl-containing Poly-pyridyl Complex on Glassy Carbon and Fluorine-doped Tin Oxide Electrodes

Published on: January 30, 2015

减小应变的多循环:一个烯离子能承受多少应变?

Ivan Aprahamian1, Graham J Bodwell, Jim J Fleming

  • 1Department of Organic Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.

Journal of the American Chemical Society
|May 27, 2004
PubMed
概括

在[n](2,7) 聚烯中压力决定了还原产品. 较短的带产生二分化和西格玛键的形成,而较长的带导致二离子物种和溶剂裂变.

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Site Directed Spin Labeling and EPR Spectroscopic Studies of Pentameric Ligand-Gated Ion Channels
11:19

Site Directed Spin Labeling and EPR Spectroscopic Studies of Pentameric Ligand-Gated Ion Channels

Published on: July 4, 2016

Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method
05:51

Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method

Published on: July 19, 2019

相关实验视频

Last Updated: Jul 16, 2026

Reductive Electropolymerization of a Vinyl-containing Poly-pyridyl Complex on Glassy Carbon and Fluorine-doped Tin Oxide Electrodes
09:17

Reductive Electropolymerization of a Vinyl-containing Poly-pyridyl Complex on Glassy Carbon and Fluorine-doped Tin Oxide Electrodes

Published on: January 30, 2015

Site Directed Spin Labeling and EPR Spectroscopic Studies of Pentameric Ligand-Gated Ion Channels
11:19

Site Directed Spin Labeling and EPR Spectroscopic Studies of Pentameric Ligand-Gated Ion Channels

Published on: July 4, 2016

Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method
05:51

Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method

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科学领域:

  • 有机化学 有机化学
  • 超分子化学 超分子化学

背景情况:

  • 烯是带有连接桥梁的多环芳化合物.
  • 了解它们的反应性对于设计新型有机材料至关重要.

研究的目的:

  • 为了研究绳索长度对[n](2,7) pyrenophanes的还原性行为的影响.
  • 阐明金属还原过程中形成的反应通路和产品.

主要方法:

  • 使用或金属减少[n](2,7) 烯 (n=7-10) .
  • 使用光谱技术分析减少产品.

主要成果:

  • 较短的绳索 ([7]-和 [2]metacyclo[2]-) 导致了还原性二元化和分子内西格玛键的形成.
  • [8](2,7) 烯仅经过了减小的二元化.
  • 较长的带 ([9]-和 [10](2,7) 聚烯) 形成了二离子反芳香物种,导致溶剂裂变.

结论:

  • 带应变是控制烯的减少途径的关键因素.
  • 观察到新的反应途径,包括西格玛键的形成和溶剂裂变.
  • 较长束的pyrenophanes的还原行为类似于pyrene本身.