Emissive and reactive excimers in a covalently-linked supramolecular multi-chromophoric system with a balanced rigid-flexible structure

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

“…quinoline M1 and methyl 2-methoxybenzoate M2 were prepared using known procedures. [25][26][27] Spectral properties: dyad Studying the electronic absorption and fluorescence spectra of a supramolecular system allows one to reveal the interaction between its subunits in the ground (S 0 ) state (for example, the formation of complexes) and in the excited (S 1 ) state (for example, the formation of excimers or exciplexes). Such interactions can be detected by comparing the properties of the system under study with those of the model compounds without any interactions.…”

“…3-{( E )-2-[4-(4-Bromo-butoxy)-phenyl]-vinyl}benzo[ f ]quinoline 1 , 3-(4-methoxystyryl)-benzo[ f ]quinoline M1 and methyl 2-methoxybenzoate M2 were prepared using known procedures. 25–27…”

“…Being a s-bonded dimer, cyclobutane is formed through an excited p-bonded dimer, a reactive excimer, and it was noted that emissive and reactive excimers can have the same or different structures. 25 The photochemical properties of the model M1 were studied earlier. 24 This SBQ photochrome undergoes reversible photoisomerization, the quantum yields of trans-cis (j tc ) and cistrans (j ct ) photoisomerization are 0.52 and 0.43, respectively.…”

“…[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. Taking into account the results of previous studies, we designed and synthesized a new biphotochromic dyad D44B, in which two identical SBQ photochromes are linked to a residue of the salicylic acid (SA) by two tetramethylene chains, Scheme 1.…”

“…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…”