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Experimental and Calculated CPL Spectra and Related Spectroscopic Data of Camphor and Other Simple Chiral Bicyclic Ketones

Authors

  • Giovanna Longhi,

    1. Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Brescia, Italy
    2. CNISM Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Roma, Italy
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  • Ettore Castiglioni,

    1. Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Brescia, Italy
    2. JASCO Europe, Cremella (LC), Italy
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  • Sergio Abbate,

    Corresponding author
    1. Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Brescia, Italy
    2. CNISM Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Roma, Italy
    • Correspondence to: Sergio Abbate, Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Viale Europa 11, 25123 Brescia, Italy. E-mail: abbate@med.unibs.it

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  • France Lebon,

    1. Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Brescia, Italy
    2. CNISM Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Roma, Italy
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  • David A. Lightner

    1. Department of Chemistry, University of Nevada, Reno, Nevada, USA
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ABSTRACT

UV, circular dichroism (CD), fluorescence and circularly polarized luminescence (CPL) spectra were recorded for a set of four related [2.2.1] bicyclic compounds ((1S,4S)-and (1R,4R)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-one, namely (1S)- and (1R)-camphor (), (1S,4R)-4,7,7-trimethylbicyclo[2.2.1]hept-5-en-2-one, (1S)-dehydro-epicamphor (), (1S,4S)-1,7,7-trimethylbicyclo[2.2.1]heptane-2,5-dione, (1S)-5-oxocamphor (), (1S,4R)- and (1R,4S)-1,7,7-trimethylbicyclo[2.2.1]heptane-2,3-dione, (1S)- and (1R)-camphorquinone ()) and a set of three related [2.2.2] bicyclic compounds (1S,4S)-bicyclo[2.2.2]octan-2,5-dione (saturated diketone ()), (1R,4R)-bicyclo[2.2.2]oct-7-en-2,5-dione (unsaturated diketone ()), ((1S,4S)-bicyclo[2.2.2]oct-7-en-5(S)-ol-2-one (which we refer to as unsaturated hydroxy-ketone ()). For the latter three compounds also mid-IR vibrational circular dichroism (VCD) spectra were recorded and are presented. Time-Dependent Density Functional (TD-DFT) calculations provide a satisfactory interpretation of both absorption and emission chiroptical spectra and permit insight into ground and excited state electronic properties. We discuss the applicability of the octant rule or of other approximated models to rationalize the observed sign of the CPL. Chirality 25:589–599, 2013. © 2013 Wiley Periodicals, Inc.

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