Unraveling ultrafast dynamics of the photoswitchable bridged dithienylethenes under structural constraints

Abstract

Photochemistry of the bridged dithienylethene series with evidence of anti-parallel/parallel interconversion along the triplet pathway.

Thermodynamic driving forces of guest confinement in a photoswitchable cage

“…23,24 Several approaches exist to increase the amount of the antiparallel form, e.g., by spatial confinement 25,26 or by bridging constraints. 27,28 Forming a cage puts a similar constraint on the open DTE ligands, and hence structures corresponding to the antiparallel conformation are prevalent, as is confirmed by the optimizations displayed in Fig. 1, thus facilitating photo-induced ring closure.…”

Cyclization Dynamics and Competitive Processes of Photochromic Perfluorocyclopentene Dithienylethylene in Solution

“…We are now concerned by the identification of X species. Such species have been reported in more or less extent for the different DTEs we studied in the past but without noticeable photodegradation. In the case of DMTPF, we know that the sample has suffered some non‐negligible photodegradation during transient experiment as proved by the presence of the by‐product absorption band after the nanosecond measurements as shown in Figure S.4 and Figure S.5.…”

“…[22,23] Indeed, the rationalization of complex excited state mechanisms are highly desired to still improve photochromic performances and so considerable investigations have been devoted worldwide to explore the excited state topologies of DTEs (or DAEs) via advanced optical spectroscopies [24][25][26][27] and/or computational chemistry. [28][29][30] In this perspective, our group has actively investigated the spectrokinetic features on the series of bridged DAEs, [31] bridged DTEs [29,32,33] or DTEs dedicated to supramolecular chemistry [34] using ultrafast spectroscopies combined with (TD)-DFT calculations. Our leitmotiv was the attempt to detangle the photochemistry of the antiparallel (AP) conformers from the photophysics of parallel (P) conformers by comparing bridged/ constrained versus free analog molecules (the initial purpose of the former being the blockade of the molecule into a photoactive conformation).…”

“…The main outcomes [32] were: (i) for the P* conformer, an Intersystem crossing (ISC) occurred (40-150 ps) to produce a first triplet state ( 3 P) after ultrafast relaxation toward S 1 relaxed state. Later on the 3 P state relaxed within few tens of μs to the ground state; (ii) for the AP* conformer, the photocyclization reaction occur immediately after light absorption (100-200 fs) starting from the Franck-Condon (FC) region while the relaxed singlet state is populated in parallel way and evolves through an ISC reaction (1-40 ps) and generate a second triplet state, 3 AP with a lifetime depending on the structural constraints; (iii) interconversion between the two triplet states has been experimentally identified, e. g. 3 AP $ 3 P only for some polyether bridged DTE (DTE-O 6 in ref [33]); (iv) an unidentified species (denoted as "X" hereafter) have been reported with variable statistical weight (0-50 %) along with the two triplet states within μs regime.…”

“On-The-Fly” Non-Adiabatic Dynamics Simulations on Photoinduced Ring-Closing Reaction of a Nucleoside-Based Diarylethene Photoswitch

“…Despite many theoretical investigations having been performed before to explore the photochromic properties of diarylethenes, most of them are concentrated on the ground state structures as well as relevant absorption spectroscopic properties [ 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 ]. In contrast, few theoretical works concerning the microscopic details of the photochromic mechanism of diarylethenes have been conducted [ 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 ].…”