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    Review of 'Bromosubstituted Norbornadienes and Their Reversible Photolytic Transformation to Quadricyclanes'

    Bromosubstituted Norbornadienes and Their Reversible Photolytic Transformation to QuadricyclanesCrossref
    I think that this is a genuine report on synthesis and basic characterization of new norbornadienes
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        Rated 4.5 of 5.
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        Rated 4 of 5.
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        Rated 5 of 5.
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        Rated 5 of 5.
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    Bromosubstituted Norbornadienes and Their Reversible Photolytic Transformation to Quadricyclanes

    Two new model systems for use within the rapidly developing ultrafast time resolved x-ray scattering techniques have been prepared. Their photoisomerisation from norbornadiene to quadricyclane was found to be a suitable reaction to follow. Simulations of scattering patterns (not included in this report) showed that if heavy atoms are included in these molecular structures, then the transformation can be followed by transient x-ray scattering techniques. Two new bromosubstituted norbornadienes were synthesised and characterised. Absorption spectroscopy showed that the norbornadienes are converted quantitatively to quadricyclanes under UV irradiation. NMR studies showed that the process was fully reversible and that the norbornadienes could be completely recovered even without addition of catalysts. Furthermore, it was shown that the formation of quadricyclane from norbornadiene was unaffected by triplet sensitizers. The two new model systems synthesised thus are strong candidates for use in time resolved x-ray scattering studies both in gas and condensed phases.

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      This work has been published open access under Creative Commons Attribution License CC BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Conditions, terms of use and publishing policy can be found at www.scienceopen.com.

      Norbonadiene Synthesis,Bromosubstituted Norbonadiene,Organic Synthesis,Bromosubstituted Quadricyclan,Norbonadiene Scaffold

      Review text

      Hammershøj et al. describes the synthesis and basic characterization of phenyl bromide functionalized norbornadienes designed to study the photo induced 2+2 cycloadition reaction known to happen in these systems. The report is well written and the experimental details comprehensive. In light of the motivation of the work - the use in time resolved pump-probe measurements quantum yield measurements as well as the thermal reversal reaction at different temperatures might reveal important parameters, such as the quantum yield of reaction and activation energy for the conversion from quadricyclane to norbornadiene, see e.g. Gray et al. Chem. Commun. 2014, 50 (40), 5330 - 5332. I am very curious to see what the time resolved measurements will bring in terms of details of the mechanism and the structures of the transition states. For a recent high level computational study, one could refer to: Ivana Antol, Journal of Computational Chemistry 2013, 34, 1439–1445.


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