{"title":"溶解增强盐桥","authors":"Ben Iddon, Christopher A Hunter","doi":"10.1021/jacs.4c11869","DOIUrl":null,"url":null,"abstract":"<p><p>Salt bridges formed by amidines and carboxylic acids represent an important class of noncovalent interaction in biomolecular and supramolecular systems. Isothermal titration calorimetry was used to study the relationships between the strength of the interaction, the chemical structures of the components, and the nature of the solvent. The stability of the 1:1 complex formed in chloroform changed by 2 orders of magnitude depending on the basicity of the amidine and the acidity of the acid, which is consistent with proton transfer in the complex. Polar solvents reduce the stabilities of salt bridges formed with <i>N,N'</i>-dialkylamidines by up to 3 orders of magnitude, but this dependence on solvent polarity can be eliminated if the alkyl groups are replaced by protons in the parent amidine. The enhanced stability of the complex formed by benzamidine is due to solvation of the NH sites not directly involved in salt bridge formation, which become significantly more polar when proton transfer takes place, leading to more favorable interactions with polar solvents in the bound state. Calculation of H-bond parameters using density functional theory was used to predict solvent effects on the stabilities of salt bridges to within 1 kJ mol<sup>-1</sup>. While H-bonding interactions are strong in nonpolar solvents, and solvophobic interactions are strong in polar protic solvents, these interactions are weak in polar aprotic solvents. In contrast, amidinium-carboxylate salt bridges are stable in both polar and nonpolar aprotic solvents, which is attractive for the design of supramolecular systems that operate in different solvent environments.</p>","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":null,"pages":null},"PeriodicalIF":14.4000,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Solvation-Enhanced Salt Bridges.\",\"authors\":\"Ben Iddon, Christopher A Hunter\",\"doi\":\"10.1021/jacs.4c11869\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><p>Salt bridges formed by amidines and carboxylic acids represent an important class of noncovalent interaction in biomolecular and supramolecular systems. Isothermal titration calorimetry was used to study the relationships between the strength of the interaction, the chemical structures of the components, and the nature of the solvent. The stability of the 1:1 complex formed in chloroform changed by 2 orders of magnitude depending on the basicity of the amidine and the acidity of the acid, which is consistent with proton transfer in the complex. Polar solvents reduce the stabilities of salt bridges formed with <i>N,N'</i>-dialkylamidines by up to 3 orders of magnitude, but this dependence on solvent polarity can be eliminated if the alkyl groups are replaced by protons in the parent amidine. The enhanced stability of the complex formed by benzamidine is due to solvation of the NH sites not directly involved in salt bridge formation, which become significantly more polar when proton transfer takes place, leading to more favorable interactions with polar solvents in the bound state. Calculation of H-bond parameters using density functional theory was used to predict solvent effects on the stabilities of salt bridges to within 1 kJ mol<sup>-1</sup>. While H-bonding interactions are strong in nonpolar solvents, and solvophobic interactions are strong in polar protic solvents, these interactions are weak in polar aprotic solvents. In contrast, amidinium-carboxylate salt bridges are stable in both polar and nonpolar aprotic solvents, which is attractive for the design of supramolecular systems that operate in different solvent environments.</p>\",\"PeriodicalId\":49,\"journal\":{\"name\":\"Journal of the American Chemical Society\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":14.4000,\"publicationDate\":\"2024-10-04\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of the American Chemical Society\",\"FirstCategoryId\":\"92\",\"ListUrlMain\":\"https://doi.org/10.1021/jacs.4c11869\",\"RegionNum\":1,\"RegionCategory\":\"化学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"CHEMISTRY, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of the American Chemical Society","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1021/jacs.4c11869","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
摘要
脒和羧酸形成的盐桥是生物分子和超分子体系中一类重要的非共价相互作用。等温滴定量热法用于研究相互作用的强度、组分的化学结构和溶剂性质之间的关系。在氯仿中形成的 1:1 复合物的稳定性会因脒的碱性和酸的酸性而发生 2 个数量级的变化,这与复合物中的质子转移是一致的。极性溶剂会降低与 N,N'-二烷基酰胺形成的盐桥的稳定性达 3 个数量级,但如果母脒中的烷基被质子取代,则可以消除这种对溶剂极性的依赖。苯甲脒形成的复合物稳定性增强的原因是没有直接参与盐桥形成的 NH 位点发生了溶解,当质子转移发生时,NH 位点的极性显著增强,从而导致在结合态下与极性溶剂发生更有利的相互作用。利用密度泛函理论计算 H 键参数,预测了溶剂对盐桥稳定性的影响,结果在 1 kJ mol-1 以内。虽然 H 键相互作用在非极性溶剂中很强,疏溶相互作用在极性质子溶剂中很强,但这些相互作用在极性烷基溶剂中很弱。相比之下,脒基羧酸盐桥在极性和非极性烷基溶剂中都很稳定,这对设计在不同溶剂环境中工作的超分子系统很有吸引力。
Salt bridges formed by amidines and carboxylic acids represent an important class of noncovalent interaction in biomolecular and supramolecular systems. Isothermal titration calorimetry was used to study the relationships between the strength of the interaction, the chemical structures of the components, and the nature of the solvent. The stability of the 1:1 complex formed in chloroform changed by 2 orders of magnitude depending on the basicity of the amidine and the acidity of the acid, which is consistent with proton transfer in the complex. Polar solvents reduce the stabilities of salt bridges formed with N,N'-dialkylamidines by up to 3 orders of magnitude, but this dependence on solvent polarity can be eliminated if the alkyl groups are replaced by protons in the parent amidine. The enhanced stability of the complex formed by benzamidine is due to solvation of the NH sites not directly involved in salt bridge formation, which become significantly more polar when proton transfer takes place, leading to more favorable interactions with polar solvents in the bound state. Calculation of H-bond parameters using density functional theory was used to predict solvent effects on the stabilities of salt bridges to within 1 kJ mol-1. While H-bonding interactions are strong in nonpolar solvents, and solvophobic interactions are strong in polar protic solvents, these interactions are weak in polar aprotic solvents. In contrast, amidinium-carboxylate salt bridges are stable in both polar and nonpolar aprotic solvents, which is attractive for the design of supramolecular systems that operate in different solvent environments.
期刊介绍:
The flagship journal of the American Chemical Society, known as the Journal of the American Chemical Society (JACS), has been a prestigious publication since its establishment in 1879. It holds a preeminent position in the field of chemistry and related interdisciplinary sciences. JACS is committed to disseminating cutting-edge research papers, covering a wide range of topics, and encompasses approximately 19,000 pages of Articles, Communications, and Perspectives annually. With a weekly publication frequency, JACS plays a vital role in advancing the field of chemistry by providing essential research.