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Nitu C, Crespi S. Computational study on the reduction and solvolysis of triplet chlorobenzenes. J PHYS ORG CHEM 2022. [DOI: 10.1002/poc.4437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Cristina Nitu
- Department of Chemistry, Ångström Laboratory Uppsala University Uppsala Sweden
- Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of Groningen, AG Groningen The Netherlands
| | - Stefano Crespi
- Department of Chemistry, Ångström Laboratory Uppsala University Uppsala Sweden
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Di Terlizzi L, Protti S, Ravelli D, Fagnoni M. Diradicals Photogeneration from Chloroaryl‐Substituted Carboxylic Acids. Chemistry 2022; 28:e202200313. [PMID: 35226781 PMCID: PMC9313617 DOI: 10.1002/chem.202200313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Indexed: 11/25/2022]
Abstract
With the aim of generating new, thermally inaccessible diradicals, potentially able to induce a double‐strand DNA cleavage, the photochemistry of a set of chloroaryl‐substituted carboxylic acids in polar media was investigated. The photoheterolytic cleavage of the Ar−Cl bond occurred in each case to form the corresponding triplet phenyl cations. Under basic conditions, the photorelease of the chloride anion was accompanied by an intramolecular electron‐transfer from the carboxylate group to the aromatic radical cationic site to give a diradical species. This latter intermediate could then undergo CO2 loss in a structure‐dependent fashion, according to the stability of the resulting diradical, or abstract a hydrogen atom from the medium. In aqueous environment at physiological pH (pH=7.3), both a phenyl cation and a diradical chemistry was observed. The mechanistic scenario and the role of the various intermediates (aryl cations and diradicals) involved in the process was supported by computational analysis.
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Affiliation(s)
| | - Stefano Protti
- PhotoGreen LabDepartment of ChemistryV. Le Taramelli 1027100PaviaItaly
| | - Davide Ravelli
- PhotoGreen LabDepartment of ChemistryV. Le Taramelli 1027100PaviaItaly
| | - Maurizio Fagnoni
- PhotoGreen LabDepartment of ChemistryV. Le Taramelli 1027100PaviaItaly
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Di Terlizzi L, Roncari F, Crespi S, Protti S, Fagnoni M. Aryl-Cl vs heteroatom-Si bond cleavage on the route to the photochemical generation of σ,π-heterodiradicals. Photochem Photobiol Sci 2021; 21:667-685. [PMID: 34775550 DOI: 10.1007/s43630-021-00119-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 10/16/2021] [Indexed: 11/30/2022]
Abstract
The photochemistry of aryl chlorides having a X-SiMe3 group (X = O, NR, S, SiMe2) tethered to the aromatic ring has been investigated in detail, with the aim to generate valuable ϭ,π-heterodiradicals. Two competitive pathways arising from the excited triplet state of the aromatics have been observed, namely heterolysis of the aryl-chlorine bond and homolysis of the X-silicon bond. The former path is found in chlorinated phenols and anilines, whereas the latter is exclusive in the case of silylated thiophenols and aryl silanes. A combined experimental/computational approach was pursued to explain such a photochemical behavior.Graphical abstract.
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Affiliation(s)
- Lorenzo Di Terlizzi
- Department of Chemistry, PhotoGreen Lab, Viale Taramelli 12, 27100, Pavia, Italy
| | - Francesca Roncari
- Department of Chemistry, PhotoGreen Lab, Viale Taramelli 12, 27100, Pavia, Italy
| | - Stefano Crespi
- Stratingh Institute for Chemistry, Center for Systems Chemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Stefano Protti
- Department of Chemistry, PhotoGreen Lab, Viale Taramelli 12, 27100, Pavia, Italy
| | - Maurizio Fagnoni
- Department of Chemistry, PhotoGreen Lab, Viale Taramelli 12, 27100, Pavia, Italy.
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Crespi S, Protti S, Ravelli D, Merli D, Fagnoni M. Sugar-Assisted Photogeneration of Didehydrotoluenes from Chlorobenzylphosphonic Acids. J Org Chem 2017; 82:12162-12172. [PMID: 29019237 DOI: 10.1021/acs.joc.7b01963] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Irradiation of the three isomeric chlorobenzylphophonic acids in aqueous buffer led to a pH-dependent photochemistry. Under acidic conditions (pH = 2.5), photocleavage of the Ar-Cl bond occurred and a phenyl cation chemistry resulted. Under basic conditions (pH = 11), a photoinduced release of the chloride anion followed by the detachment of the metaphosphate anion gave α,n-didehydrotoluene diradicals (α,n-DHTs), potential DNA cleaving intermediates. At a physiological pH (pH = 7.2), both a cationic and a diradical reactivity took place depending on the phosphonic acid used. It is noteworthy that the complexation exerted by a monosaccharide (glucose or methylglucopyranoside) present in solution induced an exclusive formation of α,n-DHTs. The mechanistic scenario of the different photoreactivities occurring when changing the pH of the solution and the role of the various intermediates (phenyl cations, diradicals, etc.) in the process was studied by computational analysis.
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Affiliation(s)
- Stefano Crespi
- PhotoGreen Lab, Department of Chemistry, University of Pavia , Viale Taramelli 12, 27100 Pavia, Italy
| | - Stefano Protti
- PhotoGreen Lab, Department of Chemistry, University of Pavia , Viale Taramelli 12, 27100 Pavia, Italy
| | - Davide Ravelli
- PhotoGreen Lab, Department of Chemistry, University of Pavia , Viale Taramelli 12, 27100 Pavia, Italy
| | - Daniele Merli
- PhotoGreen Lab, Department of Chemistry, University of Pavia , Viale Taramelli 12, 27100 Pavia, Italy
| | - Maurizio Fagnoni
- PhotoGreen Lab, Department of Chemistry, University of Pavia , Viale Taramelli 12, 27100 Pavia, Italy
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Pedroli C, Ravelli D, Protti S, Albini A, Fagnoni M. Singlet vs Triplet Reactivity of Photogenerated α,n-Didehydrotoluenes. J Org Chem 2017; 82:6592-6603. [DOI: 10.1021/acs.joc.7b00610] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Chiara Pedroli
- Department of Chemistry, PhotoGreen Lab, Viale
Taramelli 12, 27100 Pavia, Italy
| | - Davide Ravelli
- Department of Chemistry, PhotoGreen Lab, Viale
Taramelli 12, 27100 Pavia, Italy
| | - Stefano Protti
- Department of Chemistry, PhotoGreen Lab, Viale
Taramelli 12, 27100 Pavia, Italy
| | - Angelo Albini
- Department of Chemistry, PhotoGreen Lab, Viale
Taramelli 12, 27100 Pavia, Italy
| | - Maurizio Fagnoni
- Department of Chemistry, PhotoGreen Lab, Viale
Taramelli 12, 27100 Pavia, Italy
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Capaldo L, Buzzetti L, Merli D, Fagnoni M, Ravelli D. Smooth Photocatalyzed Benzylation of Electrophilic Olefins via Decarboxylation of Arylacetic Acids. J Org Chem 2016; 81:7102-9. [DOI: 10.1021/acs.joc.6b00984] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Luca Capaldo
- PhotoGreen Lab, Department
of Chemistry, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
| | - Luca Buzzetti
- PhotoGreen Lab, Department
of Chemistry, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
| | - Daniele Merli
- PhotoGreen Lab, Department
of Chemistry, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
| | - Maurizio Fagnoni
- PhotoGreen Lab, Department
of Chemistry, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
| | - Davide Ravelli
- PhotoGreen Lab, Department
of Chemistry, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
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