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Spiaggia F, Uccello Barretta G, Iuliano A, Baldassari C, Aiello F, Balzano F. A Squaramide-Based Organocatalyst as a Novel Versatile Chiral Solvating Agent for Carboxylic Acids. Molecules 2024; 29:2389. [PMID: 38792248 PMCID: PMC11123912 DOI: 10.3390/molecules29102389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 05/03/2024] [Accepted: 05/15/2024] [Indexed: 05/26/2024] Open
Abstract
A squaramide-based organocatalyst for asymmetric Michael reactions has been tested as a chiral solvating agent (CSA) for 26 carboxylic acids and camphorsulfonic acid, encompassing amino acid derivatives, mandelic acid, as well as some of its analogs, propionic acids like profens (ketoprofen and ibuprofen), butanoic acids and others. In many cases remarkably high enantiodifferentiations at 1H, 13C and 19F nuclei were observed. The interaction likely involves a proton transfer from the acidic substrates to the tertiary amine sites of the organocatalyst, thus allowing for pre-solubilization of the organocatalyst (when a chloroform solution of the substrate is employed) or the simultaneous solubilization of both the catalyst and the substrate. DOSY experiments were employed to evaluate whether the catalyst-substrate ionic adduct was a tight one or not. ROESY experiments were employed to investigate the role of the squaramide unit in the adduct formation. A mechanism of interaction was proposed in accordance with the literature data.
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Affiliation(s)
- Fabio Spiaggia
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, 56124 Pisa, Italy; (A.I.); (C.B.); (F.B.)
| | - Gloria Uccello Barretta
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, 56124 Pisa, Italy; (A.I.); (C.B.); (F.B.)
| | - Anna Iuliano
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, 56124 Pisa, Italy; (A.I.); (C.B.); (F.B.)
| | - Carlo Baldassari
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, 56124 Pisa, Italy; (A.I.); (C.B.); (F.B.)
| | - Federica Aiello
- National Research Council, Institute for Chemical and Physical Processes (CNR-IPCF), Via G. Moruzzi 1, 56124 Pisa, Italy;
| | - Federica Balzano
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, 56124 Pisa, Italy; (A.I.); (C.B.); (F.B.)
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De Luca C, Compagnin G, Nosengo C, Mazzoccanti G, Gasparrini F, Cavazzini A, Catani M, Felletti S. Novel insights into the dependence of adsorption-desorption kinetics on particle geometry in chiral chromatography. Anal Bioanal Chem 2024; 416:1809-1820. [PMID: 38358532 PMCID: PMC10901921 DOI: 10.1007/s00216-024-05186-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 01/25/2024] [Accepted: 01/29/2024] [Indexed: 02/16/2024]
Abstract
The existence of slow adsorption-desorption kinetics in chiral liquid chromatography is common knowledge. This may significantly contribute to worsening the efficiency and kinetic performance of a chromatographic run, especially when high flow rates are employed. Many attempts and protocols have been proposed to access this term, the so-called c ads , but they are based on different (theoretical) assumptions. As a consequence, no official method is available for the estimation of the adsorption-desorption kinetics term. In this work, a novel approach to access c ads is presented. This procedure combines experimental results obtained with kinetic and thermodynamic measurements. The investigations have been performed on two zwitterionic teicoplanin chiral stationary phases (CSPs) based on 1.9 μ m fully porous and 2.0 μ m superficially porous particles (FPPs and SPPs), using Z-D,L-Methionine as probe molecule. Kinetic studies have been performed through the combination of both stop-flow and dynamic measurements, while adsorption isotherms have been calculated through Inverse Method. This study has confirmed that, on both particle formats, analyte diffusion on the surface of the particle is negligible, meaning that adsorption is localized, and it has been demonstrated that adsorption-desorption kinetics is strongly dependent on particle geometry and, in particular, on the loading of chiral selector. These findings are fundamental not only to unravel novel aspects of the complex enantiorecognition mechanism but also to optimize the employment of CSPs for ultra-fast and preparative applications.
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Affiliation(s)
- Chiara De Luca
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, via L. Borsari 46, Ferrara, 44121, Italy
| | - Greta Compagnin
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, via L. Borsari 46, Ferrara, 44121, Italy
| | - Chiara Nosengo
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, via L. Borsari 46, Ferrara, 44121, Italy
| | - Giulia Mazzoccanti
- Department of Drug Chemistry and Technology, "Sapienza" Università di Roma, P.le A. Moro 5, Rome, 00185, Italy
| | - Francesco Gasparrini
- Department of Drug Chemistry and Technology, "Sapienza" Università di Roma, P.le A. Moro 5, Rome, 00185, Italy
| | - Alberto Cavazzini
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, via L. Borsari 46, Ferrara, 44121, Italy
- Council for Agricultural Research and Economics, CREA, via della Navicella 2/4, Rome, 00184, Italy
| | - Martina Catani
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, via L. Borsari 46, Ferrara, 44121, Italy.
| | - Simona Felletti
- Department of Environmental and Prevention Sciences, University of Ferrara, via L. Borsari 46, Ferrara, 44121, Italy.
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