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Experimental and Calculated CPL Spectra and Related Spectroscopic Data of Camphor and Other Simple Chiral Bicyclic Ketones
Author(s) -
Longhi Giovanna,
Castiglioni Ettore,
Abbate Sergio,
Lebon France,
Lightner David A.
Publication year - 2013
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.22176
Subject(s) - bicyclic molecule , chemistry , heptane , diketone , circular dichroism , spectral line , stereochemistry , camphor , excited state , ketone , computational chemistry , organic chemistry , physics , atomic physics , astronomy
UV, circular dichroism (CD), fluorescence and circularly polarized luminescence (CPL) spectra were recorded for a set of four related [2.2.1] bicyclic compounds ((1 S ,4 S )‐and (1 R ,4 R )‐1,7,7‐trimethylbicyclo[2.2.1]heptan‐2‐one, namely (1 S )‐ and (1 R )‐camphor ( 1 ), (1 S ,4 R )‐4,7,7‐trimethylbicyclo[2.2.1]hept‐5‐en‐2‐one, (1 S )‐dehydro‐epicamphor ( 2 ), (1 S ,4 S )‐1,7,7‐trimethylbicyclo[2.2.1]heptane‐2,5‐dione, (1 S )‐5‐oxocamphor ( 3 ), (1 S ,4 R )‐ and (1 R ,4 S )‐1,7,7‐trimethylbicyclo[2.2.1]heptane‐2,3‐dione, (1 S )‐ and (1 R )‐camphorquinone ( 4 )) and a set of three related [2.2.2] bicyclic compounds (1 S ,4 S )‐bicyclo[2.2.2]octan‐2,5‐dione (saturated diketone ( 5 )), (1 R ,4 R )‐bicyclo[2.2.2]oct‐7‐en‐2,5‐dione (unsaturated diketone ( 6 )), ((1 S ,4 S )‐bicyclo[2.2.2]oct‐7‐en‐5( S )‐ol‐2‐one (which we refer to as unsaturated hydroxy‐ketone ( 7 )). 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.