The Metacyclophanediene-Dihydropyrene Photochromic π Switch

Photoswitching Magnetic Crossover in Organic Molecular Systems

“…A total of around 30 lowest-energy transitions have been considered for each species. Results for the dimethyl derivatives are in close agreement with the experimental values measured by Mitchell …”

Electronic Excited States and UV–Vis Absorption Spectra of the Dihydropyrene/Cyclophanediene Photochromic Couple: a Theoretical Investigation

“…The contributions of the 0-0 transitions in the overall intensity of the optically active S0(1 1 Ag)®S4(1 1 Au) and S0(1 1 Ag)® S5(2 1 Bu) are ~1% and ~35%, respectively. This is in agreement with the larger structural changes computed in the 1 1 Au state than in the 2 1 Bu state with respect to the ground state of 1o (Table S7).…”

“…Based on the present results, it is difficult to determine unambiguously the order of these two electronic states. Transition to the symmetry-allowed 1 1 Bu state is expected to give rise to a weak absorption in the 3.6-3.7 eV region, in agreement with the weak absorption feature observed between 300-400 nm experimentally for CPDs. 30 The assignment of the third excited state is less problematic.…”

“…Au and 21 Bu states (see discussion above), then CAM-B3LYP, M06-2X and wB97XD clearly outperform B3LYP, B3PW91, PBE0, TPSSh and M06, as already reported in a previous study 40. …”

Cover Feature: Synthesis of a Negative Photochrome with High Switching Quantum Yields and Capable of Singlet‐Oxygen Production and Storage (Chem. Eur. J. 67/2021)

“…The unusual position of these signals is due to the ring current flowing through the delocalized p-electrons of the DHP core and constitutes thus a real signature indicating that the photochromic unit is in its closed state. [11] The structures of the other compounds investigated in this work were similarly confirmed by NMR studies (see S.I. and experimental section).…”