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Kumar V, Pilati T, Quici S, Chierotti MR, Nervi C, Gobetto R, Resnati G. Proton in a Confined Space: Structural Studies of H + ⊂Crypt-111 Iodide and Some Halogen-Bonded Derivatives. Chemistry 2017; 23:14462-14468. [PMID: 28657685 DOI: 10.1002/chem.201701699] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2017] [Revised: 06/27/2017] [Indexed: 11/06/2022]
Abstract
Experimental observations and modeling data are reported on the solid-state structural features of crypt- 111⋅HI (1) and the three-component co-crystals that 1 forms with α,ω-diiodoperfluoroalkanes 2 a-d. X-ray analyses indicate that, in all five systems and at low temperature, the caged proton is covalently bonded to a single nitrogen atom and is involved in a network of intramolecular hydrogen bonds. In contrast, room-temperature, solid-state 15 N NMR spectroscopy suggests magnetic equivalency of the two N atoms of crypt-111 in both 1 and co-crystals of 1 with diiodoperfluoroalkanes. Computational modelling confirms that the acidic hydrogen inside the cavity preferentially sits along the internitrogen axis and is covalently bonded to one nitrogen. The computed energy barriers suggest that the hopping of the encapsulated proton between the two N atoms of the cage can occur in the halogen-bonded co-crystals of 1⋅2, but it is hardly possible in the pure H+ ⊂crypt-111 iodide 1. These different pictures of the proton position and dynamics obtained by using different techniques and conditions confirm the unique characteristics of the confined space within the cavity of crypr-111 and the distinctive features of processes occurring therein.
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Affiliation(s)
- Vijith Kumar
- Nanostructured Fluorinated Materials Laboratory (NFMLab), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Via L. Mancinelli 7, 20131, Milan, Italy
| | - Tullio Pilati
- Nanostructured Fluorinated Materials Laboratory (NFMLab), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Via L. Mancinelli 7, 20131, Milan, Italy
| | - Silvio Quici
- CNR, Istituto di Scienze e Tecnologie Molecolari, Via C. Golgi 19, 20133, Milan, Italy
| | - Michele R Chierotti
- Department of Chemistry and NIS, University of Turin, Via P. Giuria 7, 10125, Turin, Italy
| | - Carlo Nervi
- Department of Chemistry and NIS, University of Turin, Via P. Giuria 7, 10125, Turin, Italy
| | - Roberto Gobetto
- Department of Chemistry and NIS, University of Turin, Via P. Giuria 7, 10125, Turin, Italy
| | - Giuseppe Resnati
- Nanostructured Fluorinated Materials Laboratory (NFMLab), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Via L. Mancinelli 7, 20131, Milan, Italy
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Abstract
This paper proposes a new type of molecular device that is able to act as an inverse proton sponge to slowly decrease the pH inside a reaction vessel. This makes the automatic monitoring of the concentration of pH-sensitive systems possible. The device is a composite formed of an alkyl chloride, which kinetically produces acidity, and a buffer that thermodynamically modulates the variation in pH value. Profiles of pH versus time (pH-t plots) have been generated under various experimental conditions by computer simulation, and the device has been tested by carrying out automatic spectrophotometric titrations, without using an autoburette. To underline the wide variety of possible applications, this new system has been used to realize and monitor HCl uptake by a di-copper(II) bistren complex in a single run, in a completely automatic experiment.
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Affiliation(s)
- Giuseppe Alibrandi
- Dipartimento di Scienze Chimiche, Università di Messina, Viale F. Stagno d'Alcontres 31, Villaggio S. Agata, 98166 Messina (Italy).
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Alibrandi G, Lister DG, Lo Vecchio C, Maeder M. [1.1.1]Cryptand: directions for its use as a variable-pH kinetic molecular device. NEW J CHEM 2014. [DOI: 10.1039/c3nj01215h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Alibrandi G, Amendola V, Bergamaschi G, Dollenz R, Fabbrizzi L, Licchelli M, Lo Vecchio C. An Automatic Molecular Dispenser of Chloride. Chemistry 2013; 19:3729-34. [DOI: 10.1002/chem.201203933] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Indexed: 11/07/2022]
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Alibrandi G, Arena CG, Lando G, Lo Vecchio C, Parisi MF. {[1.1.1]Cryptand/imidazole}: a prototype composite kinetic molecular device for automatic NMR variable pH reaction monitoring. Chemistry 2011; 17:1419-22. [PMID: 21268141 DOI: 10.1002/chem.201002725] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Indexed: 11/06/2022]
Affiliation(s)
- Giuseppe Alibrandi
- Dipartimento di Chimica Inorganica, Chimica Analitica e Chimica Fisica-Facoltà di Scienze Matematiche, Fisiche e Naturali, Università di Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy.
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Alibrandi G, Lo Vecchio C, Villari A, Villari I. Molecular apparatus for automatic titrations. Chemistry 2010; 16:7700-3. [PMID: 20533470 DOI: 10.1002/chem.201000965] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Giuseppe Alibrandi
- Dipartimento di Chimica Inorganica, Chimica Analitica e Chimica Fisica-Facoltà di Scienze Matematiche, Fisiche e Naturali, Università di Messina-Salita Sperone 31, Villaggio S. Agata, 98166 Messina, Italy.
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Alibrandi G, Lister DG, Lo Vecchio C. Towards molecular temperature programmers for variable-temperature kinetic experiments. Chemphyschem 2009; 10:3209-11. [PMID: 19830770 DOI: 10.1002/cphc.200900712] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Giuseppe Alibrandi
- Dipartimento di Chimica Inorganica, Chimica Analitica e Chimica Fisica, Università di Messina, Salita Sperone 31, Villaggio S. Agata, 98166 Messina, Italy.
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