Chapter 6
Thermo-Responsive Phosphorescence
Control Mediated by Molecular Rotation
and Aurophilic Interactions
in Amphidynamic Crystals
of Phosphine-Gold(I) Complex
Here a structural design aimed at the control of phosphorescence emission as the
result of changes in molecular rotation in a crystalline material is presented. The
proposed strategy includes the use of aurophilic interactions, both as a crystal engineering tool and as a sensitive emission probe, and the use of a dumbbell-shaped
architecture intended to create a low packing density region that permits the rotation of a central phenylene. A correlation between phosphorescence lifetimes and
rotational frequencies is interpreted in terms of conformational changes arising from
rotation of the central phenylene, which causes a change in electronic communication
between the gold-linked rotors. These results and control experiments with analogue
gold(I) complex, possessing a hindered tetramethylphenylene that is unable to rotate
in the crystal, suggest that the molecular rotation can be a useful tool for controlling
luminescence in the crystalline state.
6.1 Introduction
The precise control of luminescent properties in solid-state materials has attracted
much attention because of their potential for the development of sophisticated functional materials such as sensors, transducers and external field-sensitive devices [1].
A concept that has attracted a great deal of attention in this context is the development of aggregation induced emission (AIE), pioneered by Tang and co-workers.
In this case, it has been shown that the rotation of conjugated groups within certain chromophores result in emission quenching as the excited state is able to decay
through a conical intersection (CI) [2]. Therefore, while the AIE chromophores are
non-emissive and are free to explore their torsional space in solution, aggregation
and crystallization suppress their rotational freedom and prevents access to the CI,
such that emission can be turned on in the solid state.
© Springer Nature Singapore Pte Ltd. 2020
M. Jin, Novel Luminescent Crystalline Materials of Gold(I) Complexes
with Stimuli-Responsive Properties, Springer Theses,
https://doi.org/10.1007/978-981-15-4063-9_6
157
Thermo-Responsive Phosphorescence
Control Mediated by Molecular Rotation
and Aurophilic Interactions
in Amphidynamic Crystals
of Phosphine-Gold(I) Complex
Here a structural design aimed at the control of phosphorescence emission as the
result of changes in molecular rotation in a crystalline material is presented. The
proposed strategy includes the use of aurophilic interactions, both as a crystal engineering tool and as a sensitive emission probe, and the use of a dumbbell-shaped
architecture intended to create a low packing density region that permits the rotation of a central phenylene. A correlation between phosphorescence lifetimes and
rotational frequencies is interpreted in terms of conformational changes arising from
rotation of the central phenylene, which causes a change in electronic communication
between the gold-linked rotors. These results and control experiments with analogue
gold(I) complex, possessing a hindered tetramethylphenylene that is unable to rotate
in the crystal, suggest that the molecular rotation can be a useful tool for controlling
luminescence in the crystalline state.
6.1 Introduction
The precise control of luminescent properties in solid-state materials has attracted
much attention because of their potential for the development of sophisticated functional materials such as sensors, transducers and external field-sensitive devices [1].
A concept that has attracted a great deal of attention in this context is the development of aggregation induced emission (AIE), pioneered by Tang and co-workers.
In this case, it has been shown that the rotation of conjugated groups within certain chromophores result in emission quenching as the excited state is able to decay
through a conical intersection (CI) [2]. Therefore, while the AIE chromophores are
non-emissive and are free to explore their torsional space in solution, aggregation
and crystallization suppress their rotational freedom and prevents access to the CI,
such that emission can be turned on in the solid state.
© Springer Nature Singapore Pte Ltd. 2020
M. Jin, Novel Luminescent Crystalline Materials of Gold(I) Complexes
with Stimuli-Responsive Properties, Springer Theses,
https://doi.org/10.1007/978-981-15-4063-9_6
157