A recent study led by F. Glöcklhofer from Imperial College, London, investigates the properties of substituted conjugated macrocycles. The first (pre-review) version just appeared on Open Research Europe:
Computations reveal the local and global aromaticity of the macrocycles in various electronic states by using the VIST method along with a discussion of the nodal structures of the orbitals.
Dominant natural difference orbitals (NDOs) (blue/red for electron detachment; green/orange for attachment) for different electronic states of O-PCT (C2 rotamer) and VIST plots for the S0 and T1 states at the S1 geometry. Copyright 2021 Pletzer M. et al. (CC-BY 4.0).
A recent study, led by Benjamin Buckley and Felipe Iza from Loughborough University, presents an innovative use of carbon dioxide. Using a plasma, carbon dioxide is turned into a source of atomic oxygen, which is used as a waste-free oxidant for the oxidation of alkenes to epoxides. The study, a collaborative work between engineering, synthesis and computation, just appeared in Chemical Science: Oxygen Harvesting from Carbon Dioxide: Simultaneous Epoxidation and CO Formation.
The main idea behind this work is to use symmetry-selection rules and the associated forbidden transitions to probe how inversion symmetry is broken during the photodynamics. See [JPCL 2021, 12, 4067] for an initial discussion of the idea.
Can you sort these molecules according to increasing triplet excitation energies?
Some basic considerations might suggest that energies go down as the size of the molecule increases. But this is incorrect. The decisive feature of these molecules is their ground-state antiaromaticity along with their potential for excited-state Baird aromaticity. Triplet excitation energies increase sharply going from 1 (0.1 eV) via 2 (1.9 eV) to 3 (2.6 eV). This can be understood in the sense that antiaromaticity is blurred as the molecule becomes larger.
More strikingly, when going from 3 to 4 or 5, the energy drops again dramatically down to 1.0 eV. This effect is explained following Ayub et al. by the simple fact that these molecule possess resonance structures with simultaneous quartets and sextets.
A new study led by J. Lachner from the Helmholtz-Zentrum Dresden describes a method for detecting 26Al via Ion-Laser Interaction Mass Spectrometry using a particle accelerator.
Quantum chemical calculations highlight the different energetics of 26MgO and 26AlO, which are separated with high specificity despite being isobars.
A new study led by C. Heshmatpour and J. Hauer from TU München studies exciton-exciton annihilation in a squaraine trimer. The experiment exploits 5th-order optical spectroscopy to study the evolution of the trimer after two-photon excitation into its bi-exciton state. Quantum chemistry computations performed by M. Menger, now located at Groningen, provide the required parameters to model the experimental signals within a Frenkel exciton model. The associated article Annihilation Dynamics of Molecular Excitons Measured at a Single Perturbative Excitation Energy just appeared in J. Phys. Chem. Lett.
Privacy & Cookies: This site uses cookies. By continuing to use this website, you agree to their use.
To find out more, including how to control cookies, see here:
Cookie Policy
