Excited-states of a rhenium carbonyl diimine complex: solvation models, spin-orbit coupling, and vibrational sampling effects.

Sebastian Mai,Aurora Muñoz-Losa,Hugo Gattuso,Chantal Daniel,Antonio Monari,Maria Fumanal,Leticia González

doi:10.1039/c7cp05126c

Abstract

We present a quantum-chemical investigation of the excited states of the complex [Re(CO)3(Im)(Phen)]+ (Im = imidazole; Phen = 1,10-phenanthroline) in solution including spin-orbit couplings and vibrational sampling. To this aim, we implemented electrostatic embedding quantum mechanics/molecular mechanics (QM/MM) in the Amsterdam Density Functional program suite, suitable for time-dependent density functional calculations including spin-orbit couplings. The new implementation is employed to simulate the absorption spectrum of the complex, which is compared to the results of implicit continuum solvation and frozen-density embedding. Molecular dynamics simulations are used to sample the ground state conformations in solution. The results demonstrate that any study of the excited states of [Re(CO)3(Im)(Phen)]+ in solution and their dynamics should include extensive sampling of vibrational motion and spin-orbit couplings.

Highlights

Rhenium(I) carbonyl diimine complexes are a fascinating class of molecules with interesting photochemical and photophysical properties
We report the implementation of electrostatic-embedding quantum mechanics/molecular mechanics (QM/MM)[32] for DFT and time-dependent density functional theory (TD-DFT) within the Amsterdam Density Functional (ADF)
The computational details of the QM/MM trajectory are given in the Electronic supplementary information (ESI)† and the results in Fig. S2 ( ESI†), which compares the absorption spectrum and excited state energies will be discussed

Summary

Introduction

Rhenium(I) carbonyl diimine complexes are a fascinating class of molecules with interesting photochemical and photophysical properties They are involved in the study of longrange electron transfer processes in proteins across distances longer than 10 Å.1. The CQO stretching frequencies depend sensitively on the electronic structure, allowing to monitor the excited states with timeresolved infrared spectroscopy.[10] the complexes show strong emission spectra that are susceptible to the environment. These complexes show a wide range of prospective applications:[11] they can be employed as photocatalysts for CO2 reduction,[12,13] as phosphorescent labels,[14] for sensors,[15] for molecular switches,[16] and are promising in the development of OLEDs.[17]

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Results

Conclusion