Reversible [2+2] Photocycloaddition in Supramolecular Covalently Bound Dyad with 3-(4-Oxystyryl)benzo[f]quinoline as Photochrome and o-Xylene Bridge Group

[2+2] Photocycloaddition in a bichromophoric dyad: photochemical concerted forward reaction following Woodward–Hoffmann rules and photoinduced stepwise reverse reaction of the ring openingviapredissociation

“…These maxima are characteristic of the benzoquinoline core and indicate a break of the SBQ π-conjugated system. Taking into account an analogy in properties of the dyad D44B and previously studied supramolecular systems with the SBQ photochromes, 22–25 the final spectrum 10 in Fig. 4 can be attributed to the cyclobutane CB44B , which forms from the dyad D44B as a result of the PCA reaction, Scheme 4.…”

“…19 We have recently found that supramolecular systems, dyads and triads, with covalently linked styrylbenzoquinoline (SBQ) photochromes are suitable objects for studying the PCA reaction. [20][21][22][23][24] Using a balanced rigid-flexible linker between SBQ units, we observed for the first time both emissive and reactive excimers in the PCA reaction. 25 The present paper is aimed at studying photochemical cyclobutane formation and especially at a more detailed study of photoinduced cyclobutane ring opening.…”

“…We have recently found that supramolecular systems, dyads and triads, with covalently linked styrylbenzoquinoline (SBQ) photochromes are suitable objects for studying the PCA reaction. 20–24 Using a balanced rigid-flexible linker between SBQ units, we observed for the first time both emissive and reactive excimers in the PCA reaction. 25…”

Interplay between Electronic Energy Transfer and Reversible Photoreactions in a Triad Comprising Two Different Styrylbenzoquinoline Photochromes and a ′Hidden′ Quencher

“…The complete kinetic scheme of the biphotochromic system photolysis, taking into account the photoisomerization and PCA reactions according to Schemes 3 and 4, respectively, includes a system of five differential equations and has been discussed earlier, [29,37] for convenience, the system is reproduced in the Supporting information. For the simplification, we assume that in all of the triad isomers, the trans-cis (E!Z) and cis-trans (Z!E) photoisomerization reactions of the same SBQ photochromes proceed with the same quantum yields ϕ tc and ϕ ct , respectively.…”

Density functional theory study of the styrylbenzoquinoline dyad and the related dibenzoquinolylcyclobutane formed in the [2 + 2] photocycloaddition reaction

“…We have recently found that, as a result of the PCA reaction, supramolecular systems with two covalently linked styrylbenzoquinoline (SBQ) photochromes produce cyclobutanes with two benzoquinoline (BQ) substituents [48][49][50][51]. For example, the dyad D44B produces the rctt-cyclobutane stereoisomer CB44B with two vicinal BQ substituents in a syn-position; this isomer is formed from the folded head-to-head dyad conformer, Scheme 1.…”