Browsing by Subject "Excited states"

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    Catalysis in the excited state: bringing innate transition metal photochemistry into play
    (American Chemical Society, 2005-03-05) Juliá Hernández, Fabio; Química Inorgánica; Facultad de Química
    Transition metal catalysis is an indispensable tool for organic synthesis that has been harnessed, modulated and perfected for many decades by careful selection of metal centers and ligands, giving rise to synthetic methods with unparalleled efficiency and chemoselectivity. Recent developments have demonstrated how light irradiation can also be recruited as a powerful tool to dramatically alter the outcome of catalytic reactions, providing access to innovative pathways with remarkable synthetic potential. In this context, the adoption of photochemical conditions as a mainstream strategy to drive organic reactions has unveiled exciting opportunities to exploit the rich excited-state framework of transition metals for catalytic applications. This Perspective examines the advances on the application of transition metal complexes as standalone photocatalysts, exploiting the innate reactivity of their excited states beyond the common use as photoredox catalysts. An account of relevant examples is dissected to provide a discussion on the electronic reorganization, the orbitals involved and the associated reactivity of different types of excited states. This analysis aims to provide practitioners with fundamental principles and guiding strategies to understand, design and apply light-activation strategies to homogeneous transition metal catalysis for organic synthesis.
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    NEXMD v2.0 Software package for nonadiabatic excited state molecular dynamics simulations
    (American Chemical Society, 2023-07-28) Freixas, Victor M.; Malone, Walter; Li, Xinyang; Song, Huajing; Negrin Yuvero, Hassiel; Pérez Castillo, Royle; White, Alexander; Gibson, Tammie R.; Makhov, Dmitry V.; Shalashilin, Dmitrii V.; Zhang, Yu; Fedik, Nikita; Kulichenko, Maksim; Messerly, Richard; Mohanam, Luke Nambi; Sharifzadeh, Sahar; Bastida, Adolfo; Mukamel, Shaul; Fernández Alberti, Sebastián; Química Física
    We present NEXMD version 2.0, the second release of the NEXMD (Nonadiabatic EXcited-state Molecular Dynamics) software package. Across a variety of new features, NEXMD v2.0 incorporates new implementations of two hybrid quantum-classical dynamics methods, namely, Ehrenfest dynamics (EHR) and the AbInitio Multiple Cloning sampling technique for Multiconfigurational Ehrenfest quantum dynamics (MCE-AIMC or simply AIMC), which are alternative options to the previously implemented trajectory surface hopping (TSH) method. To illustrate these methodologies, we outline a direct comparison of these three hybrid quantum-classical dynamics methods as implemented in the same NEXMD framework, discussing their weaknesses and strengths, using the modeled photodynamics of a polyphenylene ethylene dendrimer building block as a representative example. We also describe the expanded normal-mode analysis and constraints for both the ground and excited states, newly implemented in the NEXMD v2.0 framework, which allow for a deeper analysis of the main vibrational motions involved in vibronic dynamics. Overall, NEXMD v2.0 expands the range of applications of NEXMD to a larger variety of multichromophore organic molecules and photophysical processes involving quantum coherences and persistent couplings between electronic excited states and nuclear velocity