Redirecting of Charge Transfer Enables the Control of the Photoactivity of Terarylenes

Abstract

Photoinduced charge transfer affects the efficiency and selectivity of photochemical reactions. Incorporation of donating groups into the isoquinolinium core allowed us to overcome the photochemical inactivity of the corresponding dithienyl-substituted terarylenes, presumably by redirecting the charge transfer within the molecule, and gave access to a new family of thermally reversible photoswitches.

Triphenylcyclopentadienyl Rhodium Complexes in Catalytic C–H Annulations. Application for Synthesis of Natural Isocoumarins

“…Notably, the developed protocol proved to be effective for using 1,2-bis­(2,5-dimethylthiophen-3-yl)­ethyne as an alkyne coupling partner. The corresponding isoquinolinium salt 12ag displays photochromic behavior and was isolated in 75% yield under catalysis with 1b ; in the case of the classical [Cp*RhCl 2 ] 2 catalyst, the yield was noticeably lower (63%). At the same time, the reaction of 6a with p -chlorobenzaldehyde catalyzed by 1b gave isoquinolinium salt 12da in a moderate yield (41%), while a similar reaction with p -nitrobenzaldehyde did not afford the desired product 12ea at all.…”

“…Minor atropisomer . 1 H (400 MHz, CDCl 3 ) δ 9.31 (s, 1H), 8.37 (d, J = 9.1 Hz, 1H), 7.49 (d, J = 9.1 Hz, 1H), 7.24–7.26 (m, 2H), 7.15–7.17 (m, 2H), 6.92 (d, J = 1.6 Hz, 1H), 6.35 (s, 1H), 6.19 (s, 1H), 3.90 (s, 3H), 2.36 (s, 3H), 2.33 (s, 3H), 2.17 (s, 3H), 2.05 (s, 3H), 1.96 (s, 3H) (cf …”

Tandem C–H Annulation Reaction of Benzaldehydes and Aminobenzoic Acids with Two Equivalents of Alkyne toward Isocoumarin-Conjugated Isoquinolinium Salts: A Family of Organic Luminophores

“…The classical rhodium complex [Cp*RhCl 2 ] 2 was used as a catalytic system at 2.5 mol % loading with the addition of 20 mol % of AgBF 4 and 2 equiv of Cu(OAc) 2 in methanol. These conditions have already proved their suitability for the synthesis of both isocoumarins and isoquinolinium salts. , Stirring at 80 °C for 8 h under argon gave the desired isocoumarin-conjugated isoquinolinium cation 4aaa in 72% yield as a sole product (entry 1). The yield of 4aaa increased to 85% using 3 equiv of Cu(OAc) 2 as an oxidant (entry 2).…”

Tuning the photochemical ring-closing reaction efficiency in diarylethene-based photoswitches through engineering of internal charge transfer

“…31 Moreover, the isomerization can even be suppressed because of the stabilization of the photo-inactive twisted intramolecular charge transfer (TICT) excited state in polar solvents. 32,33 Nonetheless, the reactivity can be recovered by properly directing the internal CT, as recently reported by Lvov et al for a series of isoquinolinium-based terarylenes, 34 first introduced by Wolf and co-workers. 35 However, to make this ''electronic approach'' more useful and successful, there is clearly a need to rationalize the impact of the introduction of donor and acceptor functional groups on the photocyclization quantum yield so to provide a method to control and tune the photochromic properties, if possible.…”

“…31 Moreover, the isomerization can even be suppressed because of the stabilization of the photo-inactive twisted intramolecular charge transfer (TICT) excited state in polar solvents. 32,33 Nonetheless, the reactivity can be recovered by properly directing the internal CT, as recently reported by Lvov et al for a series of isoquinolinium-based terarylenes, 34 first introduced by Wolf and co-workers. 35…”