{"title":"Molecular insights into the complex formation between dodecamethylcucurbit[6]uril and phenylenediamine isomers","authors":"Venkataramanan Natarajan Sathiyamoorthy, Ambigapathy Suvitha, Ryoji Sahara","doi":"10.1007/s10847-022-01144-3","DOIUrl":null,"url":null,"abstract":"<div><p>The complexation behavior of diprotonated phenylenediamine isomers with decamethylene cucurbit[6]uril (Me<sub>12</sub>Q[6]) in 1:1 and 1:2 stoichiometry was investigated in vacuum and solution using density functional theory (DFT). Among the isomers, <i>o-</i>phenylenediamine (<i>o</i>PDA) forms an exclusion complex in 1:1 stoichiometry, while others form an inclusion complex. In the 1:2 stoichiometry, at least one of the guest molecule lie on the surface of the Me<sub>12</sub>Q[6] cavity. The structural reorganization was found to depend on the mode of interaction of the guest molecule. In the gas phase, the enthalpy and Gibbs free energy are negative for all the complexes demonstrating the encapsulation process is spontaneous and thermodynamically favorable. In the solution phase, the enthalpy and entropy are negative for complexes with guest molecules <i>meta</i>- and <i>para</i>-isomers of phenylenediamine. For <i>o</i>PDA as a guest, the enthalpy and entropy are positive indicating the complex formation to be nonspontaneous. The MESP isosurface of complexes shows a higher accumulation of charge in the 1:2 stoichiometry, which reduces their stability. AIM analysis shows the interaction between <i>o</i>PDA and Me<sub>12</sub>Q[6] is due to hydrogen bonding with moderate strength, while for the other isomers, interactions between the benzene group and the Me<sub>12</sub>Q[6] cavity were noticed. EDA analysis shows the larger contribution is the electrostatic attraction and it decreases with the increase in the guest ratio. The formation of inclusion complexes by mPDA and pPDA and the surface adsorption of <i>o</i>PDA on Me<sub>12</sub>Q[6] and the higher accumulation of positive charge during solvation in <i>o</i>PDA@Me<sub>12</sub>Q[6] complexes make them labile in the solution phase.</p><h3>Graphical abstract</h3>\n <figure><div><div><div><picture><source><img></source></picture></div></div></div></figure>\n </div>","PeriodicalId":54324,"journal":{"name":"Journal of Inclusion Phenomena and Macrocyclic Chemistry","volume":null,"pages":null},"PeriodicalIF":1.7000,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Inclusion Phenomena and Macrocyclic Chemistry","FirstCategoryId":"92","ListUrlMain":"https://link.springer.com/article/10.1007/s10847-022-01144-3","RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 1
Abstract
The complexation behavior of diprotonated phenylenediamine isomers with decamethylene cucurbit[6]uril (Me12Q[6]) in 1:1 and 1:2 stoichiometry was investigated in vacuum and solution using density functional theory (DFT). Among the isomers, o-phenylenediamine (oPDA) forms an exclusion complex in 1:1 stoichiometry, while others form an inclusion complex. In the 1:2 stoichiometry, at least one of the guest molecule lie on the surface of the Me12Q[6] cavity. The structural reorganization was found to depend on the mode of interaction of the guest molecule. In the gas phase, the enthalpy and Gibbs free energy are negative for all the complexes demonstrating the encapsulation process is spontaneous and thermodynamically favorable. In the solution phase, the enthalpy and entropy are negative for complexes with guest molecules meta- and para-isomers of phenylenediamine. For oPDA as a guest, the enthalpy and entropy are positive indicating the complex formation to be nonspontaneous. The MESP isosurface of complexes shows a higher accumulation of charge in the 1:2 stoichiometry, which reduces their stability. AIM analysis shows the interaction between oPDA and Me12Q[6] is due to hydrogen bonding with moderate strength, while for the other isomers, interactions between the benzene group and the Me12Q[6] cavity were noticed. EDA analysis shows the larger contribution is the electrostatic attraction and it decreases with the increase in the guest ratio. The formation of inclusion complexes by mPDA and pPDA and the surface adsorption of oPDA on Me12Q[6] and the higher accumulation of positive charge during solvation in oPDA@Me12Q[6] complexes make them labile in the solution phase.
期刊介绍:
The Journal of Inclusion Phenomena and Macrocyclic Chemistry is the premier interdisciplinary publication reporting on original research into all aspects of host-guest systems. Examples of specific areas of interest are: the preparation and characterization of new hosts and new host-guest systems, especially those involving macrocyclic ligands; crystallographic, spectroscopic, thermodynamic and theoretical studies; applications in chromatography and inclusion polymerization; enzyme modelling; molecular recognition and catalysis by inclusion compounds; intercalates in biological and non-biological systems, cyclodextrin complexes and their applications in the agriculture, flavoring, food and pharmaceutical industries; synthesis, characterization and applications of zeolites.
The journal publishes primarily reports of original research and preliminary communications, provided the latter represent a significant advance in the understanding of inclusion science. Critical reviews dealing with recent advances in the field are a periodic feature of the journal.