title: Experimental and calculated CPL spectra and related spectroscopic data of camphor and other simple chiral bicyclic ketones.
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.
authors.affiliation: Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Brescia, Italy; CNISM Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Roma, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Longhi
authors.forename: Ettore
authors.initials: E
authors.lastname: Castiglioni
authors.forename: Sergio
authors.initials: S
authors.lastname: Abbate
authors.forename: France
authors.initials: F
authors.lastname: Lebon
authors.forename: David A
authors.initials: DA
authors.lastname: Lightner
mesh_terms: D001643:Bridged Bicyclo Compounds / Q000737:chemistry*; D002164:Camphor / Q000737:chemistry*; D002942:Circular Dichroism; D003198:Computer Simulation; D015394:Molecular Structure; D011789:Quantum Theory; D013237:Stereoisomerism
chemical_list: D001643:Bridged Bicyclo Compounds; D002164:Camphor
keywords: TDDFT (Time-Dependent Density Functional Theory) calculations; VCD (vibrational circular dichroism); [2.2.1] and [2.2.2] bicyclic ketones; circular dichroism (CD); circularly polarized luminescence (CPL); g factor; ground and excited state; octant rule