Institution: | 1. Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
Leibniz Institute of Photonic Technology Jena (Leibniz-IPHT), Albert-Einstein-Str. 9, 07745 Jena, Germany;2. Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany;3. Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
Leibniz Institute of Photonic Technology Jena (Leibniz-IPHT), Albert-Einstein-Str. 9, 07745 Jena, Germany
Abbe Center of Photonics (ACP), Albert-Einstein-Str. 6, 07745 Jena, Germany;4. Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstr. 8, 07743 Jena, Germany;5. Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
Abbe Center of Photonics (ACP), Albert-Einstein-Str. 6, 07745 Jena, Germany |
Abstract: | In this paper, the photophysical behavior of four panchromatically absorbing, homoleptic bis(4H-imidazolato)CuI complexes, with a systematic variation in the electron-withdrawing properties of the imidazolate ligand, were studied by wavelength-dependent time-resolved femtosecond transient absorption spectroscopy. Excitation at 400, 480, and 630 nm populates metal-to-ligand charge transfer, intraligand charge transfer, and mixed-character singlet states. The pump wavelength-dependent transient absorption data were analyzed by a recently established 2D correlation approach. Data analysis revealed that all excitation conditions yield similar excited-state dynamics. Key to the excited-state relaxation is fast, sub-picosecond pseudo-Jahn-Teller distortion, which is accompanied by the relocalization of electron density onto a single ligand from the initially delocalized state at Franck-Condon geometry. Subsequent intersystem crossing to the triplet manifold is followed by a sub-100 ps decay to the ground state. The fast, nonradiative decay is rationalized by the low triplet-state energy as found by DFT calculations, which suggest perspective treatment at the strong coupling limit of the energy gap law. |