Theoretical Rationalization of the Emission Properties of Prototypical Cu(I)–Phenanthroline Complexes

Abstract

The excited state properties of transition metal complexes have become a central focus of research owing to a wide range of possible applications that seek to exploit their luminescence properties. Herein, we use density functional theory (DFT), time-dependent DFT (TDDFT), classical and quantum mechanics/molecular mechanics (QM/MM) molecular dynamics (MD) simulations to provide a full understanding on the role of the geometric and electronic structure, spin-orbit coupling, singlet-triplet gap and the solvent environment on the emission properties of nine prototypical copper(I)-phenanthroline complexes. Our calculations reveal clear trends in the electronic properties that are strongly correlated to the luminescence properties, allowing us to rationalize the role of specific structural modifications. The MD simulations show, in agreement with recent experimental observations, that the lifetime shortening of the excited triplet state in donor solvents (acetonitrile) is not due to the formation of an exciplex. Instead, the solute-solvent interaction is transient and arises from solvent structures that are similar to the ones already present in the ground state. These results based on a subset of the prototypical mononuclear Cu(I) complexes shed general insight into these complexes that may be exploited for development of mononuclear Cu(I) complexes for applications as, for example, emitters in third generation OLEDs.

Excited state decay of cyclometalated polypyridine ruthenium complexes: insight from theory and experiment

“…71,[117][118][119] Additionally, quantum chemical approaches can deliver lots of information about energies and geometries of relevant excited states. Tong, Che and coworkers (vide supra) demonstrated this on luminescent cyclometalated gold(III) complexes.…”

Nonadiabatic transition state theory: Application to intersystem crossings in the active sites of metal‐sulfur proteins

“…Among many examples of processes where intersystem crossings play a central role are combustion, reactions in the atmosphere and in interstellar space, transition metal‐based catalysis, and binding of small molecules to the active sites of metalloproteins . Intersystem crossing has applications in photodynamic therapy, free‐radical polymerization reactions, organic‐light emitting diodes, and metal–organic frameworks . Therefore, it is not surprising that, given the importance and widespread nature of intersystem crossings, the methods for calculating the rates of these nonradiative transitions between electronic states with different spin multiplicities have attracted a lot of interest in recent years …”

“…In principle, the rates of intersystem crossings can be calculated by solving the quantum Schrödinger or classical Newton equations for the nuclear motion on the multiple coupled electronic PESs using nonadiabatic ab initio molecular dynamics (NA‐AIMD). In the most of the applications of NA‐AIMD to intersystem crossings, the classical nuclear trajectories are propagated on the PESs prebuild or calculated “on the‐fly” along the nuclear trajectories . The last approach, also called direct dynamics , can be applied to relatively large systems with dozens of atoms.…”

Origin of the Photoinduced Geometrical Change of Copper(I) Complexes from the Quantum Chemical Topology View

“…To understand the photophysics of [Cu(phen) 2 ] + , DFT and time‐dependent DFT (TD‐DFT) calculations were performed. TD‐DFT methods have been widely used to study these kinds of systems, giving good agreement with experimental data by describing correctly the charge‐transfer phenomenon and the excited state flattening distortions . This motion was explored by scanning the dihedral angle between both the phenanthroline rings from 90 to 10° in four different electronic states, S 0 , S 1 , T 1 , and T 2 .…”