TY - JOUR
T1 - Electron delocalization in a rigid cofacial naphthalene-1,8:4,5- bis(dicarboximide) dimer
AU - Wu, Yilei
AU - Frasconi, Marco
AU - Gardner, Daniel M.
AU - McGonigal, Paul R.
AU - Schneebeli, Severin T.
AU - Wasielewski, Michael R.
AU - Stoddart, J. Fraser
PY - 2014/9/1
Y1 - 2014/9/1
N2 - Investigating through-space electronic communication between discrete cofacially oriented aromatic π-systems is fundamental to understanding assemblies as diverse as double-stranded DNA, organic photovoltaics and thin-film transistors. A detailed understanding of the electronic interactions involved rests on making the appropriate molecular compounds with rigid covalent scaffolds and π-π distances in the range of ca. 3.5 Å. Reported herein is an enantiomeric pair of doubly-bridged naphthalene-1,8:4,5- bis(dicarboximide) (NDI) cyclophanes and the characterization of four of their electronic states, namely 1) the ground state, 2) the exciton coupled singlet excited state, 3) the radical anion with strong through-space interactions between the redox-active NDI molecules, and 4) the diamagnetic diradical dianion using UV/Vis/NIR, EPR and ENDOR spectroscopies in addition to X-ray crystallography. Despite the unfavorable Coulombic repulsion, the singlet diradical dianion dimer of NDI shows a more pronounced intramolecular π-π stacking interaction when compared with its neutral analog. Two are better than one: A doubly-bridged naphthalene diimide (NDI) cyclophane has been synthesized. It shows efficient π-orbital overlap between two rigid cofacial NDI units. The resulting through-space electronic delocalization in the neutral as well as reduced states induces emergent photophysical, electrochemical, and magnetic properties both in solution and in the solid phase.
AB - Investigating through-space electronic communication between discrete cofacially oriented aromatic π-systems is fundamental to understanding assemblies as diverse as double-stranded DNA, organic photovoltaics and thin-film transistors. A detailed understanding of the electronic interactions involved rests on making the appropriate molecular compounds with rigid covalent scaffolds and π-π distances in the range of ca. 3.5 Å. Reported herein is an enantiomeric pair of doubly-bridged naphthalene-1,8:4,5- bis(dicarboximide) (NDI) cyclophanes and the characterization of four of their electronic states, namely 1) the ground state, 2) the exciton coupled singlet excited state, 3) the radical anion with strong through-space interactions between the redox-active NDI molecules, and 4) the diamagnetic diradical dianion using UV/Vis/NIR, EPR and ENDOR spectroscopies in addition to X-ray crystallography. Despite the unfavorable Coulombic repulsion, the singlet diradical dianion dimer of NDI shows a more pronounced intramolecular π-π stacking interaction when compared with its neutral analog. Two are better than one: A doubly-bridged naphthalene diimide (NDI) cyclophane has been synthesized. It shows efficient π-orbital overlap between two rigid cofacial NDI units. The resulting through-space electronic delocalization in the neutral as well as reduced states induces emergent photophysical, electrochemical, and magnetic properties both in solution and in the solid phase.
KW - cyclophane
KW - excimer emission
KW - mixed-valence compounds
KW - radical anion dimer
KW - π-electron delocalization
UR - http://www.scopus.com/inward/record.url?scp=84906946218&partnerID=8YFLogxK
U2 - 10.1002/anie.201403816
DO - 10.1002/anie.201403816
M3 - Article
C2 - 25044761
AN - SCOPUS:84906946218
SN - 1433-7851
VL - 53
SP - 9476
EP - 9481
JO - Angewandte Chemie - International Edition
JF - Angewandte Chemie - International Edition
IS - 36
ER -