Long-Lived Charge Transfer Excited States in HBC-Polypyridyl Complex Hybrids.
The synthesis of two bipyridine-hexa-peri-hexabenzocoronene (bpy-HBC) ligands functionalized with either (t)Bu or C12H25 and their Re(I) tricarbonyl chloride complexes are reported and their electronic properties investigated using spectroscopic and computational methods. The metal complexes show unusual properties, and we observed the formation of a long-lived excited state using time-resolved infrared spectroscopy. Depending on the solvent, this appears to be of the form Rebpy(•-)HBC(•+) or a bpy-centered π,π* state. TD-DFT calculations support the donor-acceptor charge transfer character of these systems, in which HBC is the donor and bpy is the acceptor. The ground state optical properties are dominated by the HBC chromophore with additional distinct transitions of the complexes, one associated with MLCT 450 nm (ε > 17 000 L mol(-1) cm(-1)) and another with a HBC/metal to bpy charge transfer, termed the MLLCT band (373 nm, ε = 66 000 L mol(-1) cm(-1)). These assignments are also supported by resonance Raman spectroscopy.
MacDiarmid Institute for Advanced Materials and Nanotechnology and Department of Chemistry, University of Otago , Dunedin, New Zealand.
Anastasia B S
AB
Elliott
Department of Chemistry, University of Nottingham , Nottingham, United Kingdom.
Raphael
R
Horvath
Department of Chemistry, University of Nottingham , Nottingham, United Kingdom.
Xue-Zhong
XZ
Sun
School of Physical Sciences (Chemistry), University of Tasmania , Private Bag 75, Hobart 7001, Australia.
Michael G
MG
Gardiner
Max Planck Institute for Polymer Research , Ackermannweg 10, Mainz 55128, Germany.
Klaus
K
Müllen
MacDiarmid Institute for Advanced Materials and Nanotechnology and Department of Chemistry, University of Otago , Dunedin, New Zealand.
Nigel T
NT
Lucas
Department of Chemistry, University of Nottingham , Nottingham, United Kingdom.|Department of Chemical and Environmental Engineering, University of Nottingham Ningbo China , 199 Talking East Road, Ningbo 315100, China.
Michael W
MW
George
MacDiarmid Institute for Advanced Materials and Nanotechnology and Department of Chemistry, University of Otago , Dunedin, New Zealand.
Keith C
KC
Gordon