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相关概念视频

Alkyl Halides02:45

Alkyl Halides

20.7K
Structural Properties
Alkyl halides are halogen-substituted alkanes wherein one or more hydrogen atoms of an alkane is replaced by a halogen atom such as fluorine, chlorine, bromine, or iodine. The carbon atom in an alkyl halide is bonded to the halogen atom, which is sp3-hybridized and exhibits a tetrahedral shape.
Unlike alkyl halides, compounds in which a halogen atom is bonded to an sp2 -hybridized carbon atom of a carbon-carbon double bond (C=C) are called vinyl halides. Whereas aryl...
20.7K
Basicity of Aliphatic Amines01:21

Basicity of Aliphatic Amines

7.0K
Amines can behave as Brønsted–Lowry bases by accepting a proton from the acid to form corresponding conjugate acids. Due to a lone pair of nonbonding electrons, aliphatic amines can also act as Lewis bases by forming a covalent bond with an electrophile.
To measure the basicity of amines, two conventions are generally used. The first defines Kb as the basicity constant for the deprotonation reaction of water by the amine, as presented in Figure 1. Conventionally, lower Kb indicates higher...
7.0K
Ions as Acids and Bases02:54

Ions as Acids and Bases

26.9K
Salts with Acidic Ions
Salts are ionic compounds composed of cations and anions, either of which may be capable of undergoing an acid or base ionization reaction with water. Aqueous salt solutions, therefore, may be acidic, basic, or neutral, depending on the relative acid-base strengths of the salt’s constituent ions. For example, dissolving the ammonium chloride in water results in its dissociation, as described by the equation:
26.9K
Hydrogen Bonds01:04

Hydrogen Bonds

15.5K
A hydrogen bond is formed when a weakly positive hydrogen atom already bonded to one electronegative atom (for example, the oxygen in the water molecule) is attracted to another electronegative atom from another polar molecule, such as water (H2O), hydrogen fluoride (HF), or ammonia (NH3). The huge electronegativity difference between the H atom (2.1) and the atom to which it is bonded (4.0 for an F atom, 3.5 for an O atom, or 3.0 for an N atom), combined with the very small size of an H atom...
15.5K
Hydrogen Bonds00:26

Hydrogen Bonds

135.7K
Hydrogen bonds are weak attractions between atoms that have formed other chemical bonds. One of these atoms is electronegative, like oxygen, and has a partial negative charge. The other is a hydrogen atom that has bonded with another electronegative atom and has a partial positive charge.
Hydrogen Bonds Control the World!
Because hydrogen has very weak electronegativity when it binds with a strongly electronegative atom, such as oxygen or nitrogen, electrons in the bond are unequally shared....
135.7K
Relative Strengths of Conjugate Acid-Base Pairs02:29

Relative Strengths of Conjugate Acid-Base Pairs

53.2K
Brønsted-Lowry acid-base chemistry is the transfer of protons; thus, logic suggests a relation between the relative strengths of conjugate acid-base pairs. The strength of an acid or base is quantified in its ionization constant, Ka or Kb, which represents the extent of the acid or base ionization reaction. For the conjugate acid-base pair HA / A−, the ionization equilibrium equations and ionization constant expressions are
53.2K

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相关实验视频

Updated: Mar 3, 2026

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding
06:44

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding

Published on: March 24, 2018

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阳离子的H键受体参数

Sarah J Pike1, Jordan J Hutchinson2, Christopher A Hunter1

  • 1Department of Chemistry, University of Cambridge , Lensfield Road, Cambridge CB2 1EW, U.K.

Journal of the American Chemical Society
|May 5, 2017
PubMed
概括

这项研究使用UV/vis定位量化各种离子的结强度. 阳离子H键参数 (β) 可以在溶剂和捐赠者之间转移,从而能够准确地预测阳离子识别.

科学领域:

  • 超分子化学
  • 分析化学
  • 物理有机化学

背景情况:

  • 键在分子识别和自我组装中起着至关重要的作用.
  • 量化阴离子的键受体 (HBA) 强度对于理解它们在溶液中的相互作用至关重要.
  • 之前的研究通常集中在特定的离子捐赠对或有限的溶剂系统上.

研究的目的:

  • 系统地研究和量化15个离子组的键受体 (HBA) 参数 (β).
  • 评估这些HBA参数在不同中性键捐赠剂 (HBD) 和有机溶剂 (和乙) 中的可转移性.
  • 建立一种可靠的方法来预测各种化学环境中的离子识别特性.

主要方法:

  • 使用紫外线/紫外线吸收定位来监测阳离子和中性HBD之间的键复合物的形成.
  • 使用15种不同的离子和3种不同的HBD在和乙中.
  • 分析定位数据以获得每个离子的自相一致的HBA参数 (β).

主要成果:

  • 确定15个阴离子的自相一致的HBA参数 (β),包括化物,碳酸盐和硫酸盐.
  • 在不同溶剂和HBD合作伙伴之间证明了阴离子HBA参数的可转移性.
  • 鉴定出碳酸盐是异常强的HBA (β ≈ 15),明显超过中性有机HBA.

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Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex
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Vibrational Spectra of a N719-Chromophore/Titania Interface from Empirical-Potential Molecular-Dynamics Simulation, Solvated by a Room Temperature Ionic Liquid
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Vibrational Spectra of a N719-Chromophore/Titania Interface from Empirical-Potential Molecular-Dynamics Simulation, Solvated by a Room Temperature Ionic Liquid

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From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding
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Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex
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  • 发现六酸是研究中最弱的HBA,与酸相比较.
  • 在特定条件下,确认离子配对与反的效果是微不足道的.
  • 结论:

    • 阳离子HBA参数 (β) 是稳固的和可转移的,允许可预测的阳离子识别.
    • 阳离子的HBA强度与它们的结合酸的pKa无关.
    • 这项工作为设计具有特定离子结合能力的系统提供了有价值的定量框架.