Photocontrolled Molecular Assembler Based on Cucurbit[8]uril: [2+2]‐Autophotocycloaddition of Styryl Dyes in the Solid State and in Water

Abstract

Three styryl dyes of the 4-pyridine series that form syn-headto-tail dimeric pairs in polycrystalline films were synthesised. NMR and UV/Vis spectroscopic studies showed that this promotes stereospecific [2+2]-autophotocycloaddition (PCA) in the dimeric pairs to give rctt-isomers of cyclobutane derivatives. For the dye with an N-ammoniopropyl substituent, this transformation was accomplished according to the singlecrystal-to-single-crystal pattern. In aqueous solutions, the dyes and cucurbit[n]urils (CB[n], n = 7, 8) form complexes with a pseudorotaxane structure. CB [7] tends to form 1:1 complexes, and CB[8] forms 1:1 and 2:1 complexes. The structure of the termolecular complex formed by the betaine of the N-sulfonatopropyl styryl dye and CB[8] was determined by X-ray diffraction. The stability of the complexes

Stimuli‐Responsive Cucurbit[n]uril‐Mediated Host‐Guest Complexes on Surfaces

“…Structural parameters for CB[n] homologues CB [5] CB [6] CB [7] CB [8] portal diameter (Å ) (Figure 2). [20] As shown by several groups, CB [8] can be used for photo-induced chemical reactions inside the cavity, [21][22][23][24][25][26][27][28][29] and switching between CB[n]-favoring and disfavoring conformers can be achieved through applying of an external stimulus. [30][31][32][33] The role of water in host-guest complexation has received attention in numerous studies.…”

Photoprocesses of alkyl meso-thiacarbocyanine dyes in the presence of cucurbit[7]uril

“…CB(n) are important for many applications, such as drug delivery [4], molecular recognition [5,6] or supramolecular catalysis [7][8][9]. In the past decade much attention has been paid for the formation of CB(n) inclusion complexes with organic dyes [10][11][12][13].…”

Features of styryl dye crystal packings and their influence on [2 + 2] photocycloaddition reaction with single crystal retention

“…The PCA reaction is also challenging for creation of information optical recording systems. [3][4][5][6][7]9,[17][18][19][20]22,28,29,38,43,45,46 In studies of PCA reactions it is important to a priori achieve the formation of a "pre-organized" dimeric pair which shows the stacking interaction of the two molecules. 49 However, these reactions are thermal and they proceed in solution.…”

“…8,16 Many reactions of cycloaddition are known in organic chemistry, for instance -[2 + 3] cyloaddition, 47 [3 + 4] cycloaddition, 48 [4 + 2] cycloaddition. Many examples of pre-organized dimeric pairs are described in the literature via the coordination of the initial ethylene systems with metal cations 11,30,32,34,38,40,43,50 or the formation of hydrogen bonds between the components, 7,9,10,12,14,15,17,20,21,[23][24][25]29,30,40,41,46,50 as well as entering two structural units in cavitand cavitycyclodextrins, calixarenes, cucurbit [8]uril, nanocages. Whereas, PCA represents a temperature independent process.…”

“…49 However, these reactions are thermal and they proceed in solution. 17,35,36,39,40 Another approach to create the "pre-organized" dimeric pair is only possible for the PCA reaction in the solid state. It is photochemically reversible, often regio-and stereoselective and it proceeds in both solution and in the solid phase.…”