A recent study, lead by Florian Glöcklhofer from Imperial College London, explores the effect of methoxy and thiomethyl subtitutions on a formally antiaromatic macrocycle. The corresponding paper “[126.96.36.199]Paracyclophanetetraenes (PCTs): cyclic structural analogues of poly(p‑phenylene vinylene)s (PPVs)” is available via Open Research Europe, 1, 111, 2012.
The above figure compares the orbitals and aromaticity descriptors for different charge and spin states. Importantly, the symmetry is broken in the T1 state, inhibiting Baird aromaticity. By comparison, the symmetry is retained for the neutral singlet, dianion, and dication states all of which exhibit aromaticity.
Recent research led by Samantha Bodman and Steve Butler from Loughborough University presents a luminescent lanthanide probe with selective affinity for adenosine monophosphate (AMP), able to differentiate AMP from the more highly charged analogues ADP and ATP.
Density functional theory computations shed insight onto the binding modes involved.
We were interested in understanding the difference in thermally activated delayed fluorescence (TADF) between two closely related donor-acceptor-donor systems using either an anthraquinone and benzodithiophenedione acceptor units, respectively. The first one was known to be an effective TADF emitter [JACS2014, 136, 18070] whereas the second one had significantly lower quantum yield for TADF [PCCP2019, 21, 10580].
Rather than just presenting energies, it was the purpose of this paper to shed detailed insight into the wavefunctions involved. Notable differences in the wavefunctions and charge-transfer character were found between the two molecules. Even more striking differences existed between different computational methods.
After evaluating electronic structure methods, we presented geometry optimisations in solution, highlighting the importance of symmetry breaking for producing an emissive lowest singlet state. The role of different solvation models was discussed as well.
Molecules interacting with light undergo fascinating photodynamical processes inducing chemical reactions, transferring energy, or converting electronic energy into heat. These processes can be elucidated computationally via photodynamics simulations. However, these can be computationally highly demanding making the simulation of many interesting processes unfeasible.
A possible route to overcome this problem and to allow for efficient dynamics simulations is by combining vibronic coupling models (describing the energies) with the surface hopping method (describing the dynamics). We have introduced this idea two years ago [PCCP, 2019, 21, 57]. A new paper in Accounts of Chemical Research summarises developments since then: Surface Hopping Dynamics on Vibronic Coupling ModelsAcc. Chem. Res.2021, 52, 3760.
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