MLCT excited states of cuprous bis-phenanthroline coordination compounds

A Molecular-Rotor Device for Nonvolatile High-Density Memory Applications

“…where E a is the activation energy and k B is the Boltzmann's constant, curve fitting of the data acquired at T > 244 K yielded a rotational activation energy of approximately 0.3 eV, a value consistent with the theoretical quenching energy of rotation in the solution [11]. Such agreement between experiment and theory further supports the proposal of attributing the observed switching effect in the device to rotational motion within the molecular layer.…”

“…The rotation speed of this type of molecular rotor has been reported to be in the picosecond timescale, which provides a potential of high switching speed [7], [11]. This switching effect holds a great potential for high-density memory applications.…”

Ultrafast Structural Rearrangements in the MLCT Excited State for Copper(I) bis-Phenanthrolines in Solution

“…3,19,26 Despite the lack of any direct structural evidence, the exciplex formation hypothesis was supported by the correlation between accessibility of the cuprous center by the solvent and the luminescence lifetime, and was widely accepted. 3,19,[27][28][29] Recent contributions from our laboratory using laser-initiated time-resolved x-ray absorption spectroscopy (LITR-XAS) have confirmed the presence of additional coordination to the copper center by a solvent molecule (or counter ion) for photoexcited [Cu I (dmp) 2 ] + in both noncoordinating toluene 30 and strongly coordinating acetonitrile. 31 The interaction strength with the solvent molecule is much weaker in the former and stronger in the latter and is supported by the differentiation of the average copper to ligand distance in the thermally equilibrated 3 MLCT state.…”

A strong steric hindrance effect on ground state, excited state, and charge separated state properties of a CuI-diimine complex captured by X-ray transient absorption spectroscopy

“…It has been shown that the presence of bulky groups at 2,9 positions can block solvent access to the Cu center to prevent the formation of an "exciplex", lowering the energy gap between the MLCT and the ground states and accelerating the ground state recovery, and thus result in a longer MLCT lifetime and a higher emission quantum yield. 14,15,18,[26][27][28][29] These studies suggest that the excited state dynamics of Cu I diimine complexes could be controlled by the dihedral angle between the two phenanthroline ligand planes as well as the solvent accessibility to the Cu center. Previously, we have investigated the structural influence on the excited state dynamics in an extreme case of a completely locked tetrahedral coordination geometry due to the stericallybulky t-butyl groups in bis(2,9-di-tert-butyl-1,10-phenanthroline)- 19 We showed that [Cu…”