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Photochemical-mediated solid-state [2+2]-cycloaddition reactions of an unsymmetrical dibenzylidene acetone (monothiophos-dba)

DOI: 10.1039/c2ce25480h DOI Help

Authors: A. G. Jarvis (Department of Chemistry, University of York) , Hazel Sparkes (Department of Chemistry, Durham University) , S. E. Tallentire (Department of Chemistry, Durham University) , L. E. Hatcher (Department of Chemistry, University of Bath) , Mark R. Warren (Department of Chemistry, University of Bath) , P. R. Raithby (Department of Chemistry, University of Bath) , D. R. Allan (Diamond Light Source) , A. C. Whitwood (Department of Chemistry, University of York) , M. C. R. Cockett (Department of Chemistry, University of York) , S. B. Duckett (Department of Chemistry, University of York) , J. L. Clark (Department of Chemistry, University of York) , I. J. S. Fairlamb (Department of Chemistry, University of York)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Crystengcomm , VOL 14 (17) , PAGES 5564-5571

State: Published (Approved)
Published: June 2012

Abstract: A novel unsymmetrical dibenzylidene acetone (monothiophos-dba, compound 3), containing two chemically different alkene moieties, undergoes a selective photochemically-induced [2+2] cycloaddition solid-state transformation (single crystal and powder), as shown by X-ray diffraction methods. In the single crystal the rate constant for the cycloaddition reaction was determined {k = (2.3 ± 0.1) × 10[-4] s[-1], with a 69% conversion attained, which compares well with a two-photon irradiation experiment using a Nd:YAG laser pumped dye laser at 605 nm radiation (66% conversion). Full conversion was attained using powdered 3 after 43 h. A similar conversion was noted between the single crystal and powder forms (59% and 66% conversion after 5 h irradiation). Irradiation of monothiophos-dba in solution using a 325 nm laser, and monitoring by 1H NMR spectroscopy, showed that no cycloaddition occurred, but exclusive photochemically-induced trans to cis isomerisation of the alkene bond connecting the unsubstituted aryl group (cis to trans isomerisation in these electron-deficient and polarised C=C bonds occurs rapidly by thermal equilibration).

Subject Areas: Chemistry

Instruments: I19-Small Molecule Single Crystal Diffraction

Added On: 16/11/2012 12:22

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