Photodeactivation Channels of Transition
Metal Complexes: A Computational
Chemistry Perspective
Daniel Escudero
Abstract A detailed molecular-level understanding of the excited-state (ES) decay
dynamics of transition metal complexes (TMCs) is vital to develop the next generation of light-active components in a wide variety of applications related to photochemistry, including optoelectronics, photocatalysis, dye-sensitized solar cells, artificial
photosynthesis, photonics sensors and switches, and bioimaging. After photoexcitation, TMCs can undergo a plethora of interconnected relaxation processes, which
compete to each other and are controlled by the subtle interplay of electronic and
geometrical rearrangements that take place during the ES deactivation dynamics at
different timescales. Intrinsic factors such as (i) the spin and character of the electronically ES involved in the process and (ii) the energetic alignment and effective
couplings between these states do play a protagonist role in determining the preferred
deactivation channels. Extrinsic factors, such as temperature, pressure, excitation
wavelength, and environmental effects, can often strongly modify the outcome of
the photochemical processes. As kinetic control is always at play, only the fastest processes among all possible deactivation channels are generally observed. Due to their
high density of ES of various characters, TMCs usually display rich and chameleonic
ES and photochemical properties. Computational chemistry is a powerful and unique
tool to provide a microscopic and time-resolved description of these complex processes, and it often constitutes the fundamental ingredient for the interpretation of
time-resolved absorption and emission spectroscopic measurements. This chapter
provides first a general overview on this complex topic, followed by an overview
of the state-of-the-art quantum chemical and reaction dynamics methods to study
the photodeactivation dynamics of TMCs and finally illustrates the progress and
challenges in this field with recent examples from the literature. Importantly, these
examples cover the ultrafast ES decay regime but also the long-lived photodeactivation from thermally equilibrated ES.
D. Escudero (B)
Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
e-mail: daniel.escudero@kuleuven.be
© Springer Nature Switzerland AG 2019
E. Broclawik et al. (eds.), Transition Metals in Coordination Environments,
Challenges and Advances in Computational Chemistry and Physics 29,
https://doi.org/10.1007/978-3-030-11714-6_9
259
Metal Complexes: A Computational
Chemistry Perspective
Daniel Escudero
Abstract A detailed molecular-level understanding of the excited-state (ES) decay
dynamics of transition metal complexes (TMCs) is vital to develop the next generation of light-active components in a wide variety of applications related to photochemistry, including optoelectronics, photocatalysis, dye-sensitized solar cells, artificial
photosynthesis, photonics sensors and switches, and bioimaging. After photoexcitation, TMCs can undergo a plethora of interconnected relaxation processes, which
compete to each other and are controlled by the subtle interplay of electronic and
geometrical rearrangements that take place during the ES deactivation dynamics at
different timescales. Intrinsic factors such as (i) the spin and character of the electronically ES involved in the process and (ii) the energetic alignment and effective
couplings between these states do play a protagonist role in determining the preferred
deactivation channels. Extrinsic factors, such as temperature, pressure, excitation
wavelength, and environmental effects, can often strongly modify the outcome of
the photochemical processes. As kinetic control is always at play, only the fastest processes among all possible deactivation channels are generally observed. Due to their
high density of ES of various characters, TMCs usually display rich and chameleonic
ES and photochemical properties. Computational chemistry is a powerful and unique
tool to provide a microscopic and time-resolved description of these complex processes, and it often constitutes the fundamental ingredient for the interpretation of
time-resolved absorption and emission spectroscopic measurements. This chapter
provides first a general overview on this complex topic, followed by an overview
of the state-of-the-art quantum chemical and reaction dynamics methods to study
the photodeactivation dynamics of TMCs and finally illustrates the progress and
challenges in this field with recent examples from the literature. Importantly, these
examples cover the ultrafast ES decay regime but also the long-lived photodeactivation from thermally equilibrated ES.
D. Escudero (B)
Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
e-mail: daniel.escudero@kuleuven.be
© Springer Nature Switzerland AG 2019
E. Broclawik et al. (eds.), Transition Metals in Coordination Environments,
Challenges and Advances in Computational Chemistry and Physics 29,
https://doi.org/10.1007/978-3-030-11714-6_9
259