甘氨酸的α,β和γ多态体的热容量
Václav Pokorný1,2, Vojtěch Štejfa1, Jakub Havlín3
1Department of Physical Chemistry, University of Chemistry and Technology, Prague, Technická 5, CZ-166 28 Prague, Czech Republic.
Molecules (Basel, Switzerland)
|November 27, 2024
概括
这项研究为甘氨酸多态提供了基本的热力学数据,包括高达450K的热容量和相位行为.为热力学应用开发了alpha,gamma和beta甘氨酸的可靠数据.
科学领域:
- 热力学是一种热力学.
- 固态化学 固态化学
- 材料科学是一种材料科学.
背景情况:
- 准确的热力学数据对于理解和预测氨基酸的行为至关重要.
- 甘氨酸是最简单的氨基酸,存在于多种结晶形式 (多态),具有不同的特性.
- 对于糖氨酸多态体的现有热力学数据是有限的,特别是在更高的温度下.
研究的目的:
- 建立可靠的热力学数据,特别是热容量和相位行为,用于糖氨酸 (氨基酸) 的稳定多态.
- 为0K至450K的晶体甘氨酸开发全面的热力学功能.
- 提供一个完整的热力学数据集,在大气压下为所有三种已知多态糖氨酸的三种多态糖氨酸.
主要方法:
- 热重力测量分析 (TGA) 和X射线粉末衍射 (XRPD) 用于描述分解温度和晶体结构.
- 使用放松热量计 (热脉冲法) 来测量α-甘氨酸的热容量,从2K到267K.
- -卡尔维特热量计和功率补偿差异扫描热量计 (DSC) 用于将热容量测量扩展到更高的温度 (高达449K).
主要成果:
- 对α-和gamma-glycine的参考热容量分别从0K发展到450K和435K.
- 计算了α-和gamma-glycine晶体相的热力学函数.
- 对β-甘氨酸的文献数据进行了重新评估,以提供0K至295K的这种多态体的热力学数据.
结论:
- 已为所有三种多态糖氨酸建立了全面可靠的热力学数据,包括热容量和热力学函数.
- 开发的数据集将已知多态甘氨酸的热力学特性扩展到更高的温度,这对于各种应用至关重要.
- 这项工作对氨基酸热力学和固态行为的基本理解作出了重大贡献.
相关概念视频
Amino acids
88.0K
Amino acids are the monomers that comprise proteins. Each amino acid has the same fundamental structure, which consists of a central carbon atom, or the alpha (α) carbon, bonded to an amino group (NH2), a carboxyl group (COOH), and to a hydrogen atom. Every amino acid also has another atom or group of atoms bonded to the central atom known as the R group. There are 20 common amino acids present in proteins, each with a different R group. Variation in the amino acid sequence is responsible...
88.0K
Basicity of Aliphatic Amines
5.7K
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...
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...
5.7K
Inductive Effects on Chemical Shift: Overview
1.1K
The protons in unsubstituted alkanes are strongly shielded with chemical shifts below 1.8 ppm. Methine, methylene, and methyl protons appear at approximately 1.7, 1.2 and 0.7 ppm, while the proton signal from methane appears at 0.23 ppm. An electronegative substituent, such as chlorine, withdraws the electron density from the protons, increasing their chemical shift. Progressive substitution of the hydrogens in methane by chlorine shifts the proton signals increasingly downfield, to 3.05 ppm in...
1.1K
Stability of Substituted Cyclohexanes
12.4K
This lesson discusses the stability of substituted cyclohexanes with a focus on energies of various conformers and the effect of 1,3-diaxial interactions.
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
12.4K
Polymer Classification: Stereospecificity
2.4K
Polymerization generates chiral centers along the entire backbone of a polymer chain. Accordingly, the stereochemistry of the substituent group has a significant effect on polymer properties. Polymers formed from monosubstituted alkene monomers feature chiral carbons at every alternate position in the polymer backbone. Relative to the predominant orientation of substituents at the adjacent chiral carbons, the polymer can exist in three different configurations: isotactic, syndiotactic, and...
2.4K
Physical Properties of Amines
3.0K
Amines with low molecular weight are usually gaseous at room temperature, while those with high molecular weight are liquid or solids in nature. Usually, low molecular weight amines have a rotten fish-like smell. Diamines typically have a pungent smell. For instance, cadaverine and putrescine, depicted in Figure 1, are two molecules responsible for decaying tissue.
3.0K


