TY - JOUR
T1 - Obtaining enhanced circular dichroism in [4]Heterohelicenium analogues
AU - Elm, Jonas
AU - Jørgensen, Jacob Lykkebo
AU - Sørensen, Thomas Just
AU - Laursen, Bo Wegge
AU - Mikkelsen, Kurt Valentin
PY - 2012/8/30
Y1 - 2012/8/30
N2 - Electronic circular dichroism in the three helicenium analogues dimethoxyquinacridinium (DMQA +), dimethoxychromenoacridinium (DMCA +), and dimethoxychromenoxanthenium (DMCX +) were investigated in vacuum with time-dependent density functional theory methods using the CAM-B3LYP functional with the basis set 6-311++G**. The systems were thoroughly studied by designing derivatives with several different electron-donating and -withdrawing substituents while at the same time keeping the net charge of the molecule either positive, neutral, or negative. Fifty-six derivatives were examined, and we identify a superior substitution pattern that is found to be independent of the bridging atoms and gives a rotational strength close to 90 × 10 -40 esu 2 cm 2 for DMQA, DMCA, and DMCX. The optimal system shows promising applications as a chromophore because it has a highly allowed primary electronic transition with an angle between the electronic and magnetic transition dipole moments close to 50° and its chiroptical response is thereby limited only by the magnetic transition.
AB - Electronic circular dichroism in the three helicenium analogues dimethoxyquinacridinium (DMQA +), dimethoxychromenoacridinium (DMCA +), and dimethoxychromenoxanthenium (DMCX +) were investigated in vacuum with time-dependent density functional theory methods using the CAM-B3LYP functional with the basis set 6-311++G**. The systems were thoroughly studied by designing derivatives with several different electron-donating and -withdrawing substituents while at the same time keeping the net charge of the molecule either positive, neutral, or negative. Fifty-six derivatives were examined, and we identify a superior substitution pattern that is found to be independent of the bridging atoms and gives a rotational strength close to 90 × 10 -40 esu 2 cm 2 for DMQA, DMCA, and DMCX. The optimal system shows promising applications as a chromophore because it has a highly allowed primary electronic transition with an angle between the electronic and magnetic transition dipole moments close to 50° and its chiroptical response is thereby limited only by the magnetic transition.
U2 - 10.1021/jp304997b
DO - 10.1021/jp304997b
M3 - Journal article
C2 - 22857739
SN - 1089-5639
VL - 116
SP - 8744
EP - 8752
JO - Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory
JF - Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory
IS - 34
ER -