Synthesis, structure, and stereospecific cross-[2+2] photocycloaddition of pseudodimeric complexes based on ammonioalkyl derivatives of styryl dyes

Abstract

Two different styryl dyes form pseudodimeric complexes via hydrogen bonding and stacking interactions; irradiation of these complexes gives rctt-cyclobutane derivatives.

Supramolecular assembler based on cucurbit[8]uril: Photodimerization of a styryl dye in water

“…1) [9]. In aqueous solutions, using NMR spectroscopy methods, inclusion complexes between 1 and CB [8] of composition 1 : 1 and 2 : 1 were detected and it was shown that photolysis of these solutions gave the same cyclobutane stereoisomer 2 [10]. Note that practically complete conversion of the dye into the cyclobutane derivative can be attained in the presence of only 5 mol % of CB [8]; that is, the cav itand acts as a supramolecular catalyst.…”

“…The solution of the kinetic equation (10) with the initial conditions t = 0, c = c 0 is well known: c = c 0 exp(-2kt). (11) In this work, the experimentally determined value is the absorbance of the sample A = εcl; therefore, it is convenient to rewrite Eq.…”

“…232 nm was observed, which corresponded to the for mation of the cyclobutane product 2 [10]. Equation (12) describes the experimental data only at the initial stage of the process, because it was derived without allowance for the formation of the photolysis product.…”

“…The stability constant of the complex 2@CB[8] (log K 3 = 5.9 (L mol -1 )) and the quantum yield of cycloaddition (ϕ ≈ 0.07 at n ≈ 0.5) have been determined. DOI: 10 size, shape, and electronic properties of the macrocy cle cavity can stabilize certain conformers of guest molecules and maintain their mutual orientation favorable for the photoreaction. In this case, the guest molecules are noncovalently bound with the host mol ecule, which is not involved in the final photoproduct, and the action of the cavitand cavity can resemble the action of a catalyst.…”

Pseudodimeric Complexes of an (18-Crown-6)stilbene with Styryl Dyes Containing an Ammonioalkyl Group: Synthesis, Structure, and Stereospecific [2 + 2] Cross-Photocycloaddition

“…Previously, 5,6 we have demonstrated that two-site binding of olefins is not a necessary condition for stereospecific synthesis of cyclobutane derivatives. This study is concerned with (18crown-6)stilbene (E)-1, N-ammonioalkyl (E)-4-(4-methyl-thiostyryl)pyridine derivatives (E)-2, and their pseudodimeric complexes (Scheme 1).…”