Synthesis, Structure, and Properties of Supramolecular Photoswitches Based on Ammonioalkyl Derivatives of Crown Ether Styryl Dyes

Abstract

The synthesis of new styryl dyes derived from 4-pyridine and 4-quinoline and having an ammonioalkyl N-substituent and benzocrown ether moieties of different sizes and with different sets of heteroatoms was developed. Spontaneous "head-to-tail" dimerization of these dyes via the formation of numerous hydrogen bonds between the terminal NH3(+) groups and crown ether moieties was detected in MeCN solutions. The stability constants of the dimeric complexes having pseudocyclic structure were studied by (1)H NMR titration. The most stable complexes (log Kd up to 8.2) were found in the case of dyes with the 18-crown-6 ether moiety, which is most complementary for binding a primary ammonium group. Stacking interaction of the conjugated systems in the dimeric complexes contributes to their stability to a much lesser extent. In dimeric complexes, the ethylene bonds of the dyes are preorganized for stereospecific [2 + 2] photocycloaddition (PCA) induced by visible light. PCA yields only rctt isomers of bis-crown-containing cyclobutane derivatives. The dyes were studied by X-ray diffraction; it was found that the dimeric arrangement is also retained in the crystalline state. The possibility of topochemical PCA of the dyes in single crystals without their destruction was demonstrated. The possibility of retro-PCA of the obtained cyclobutane derivatives to give the starting dyes was shown. The elucidated regularities of PCA can be used to fabricate optical data recording systems based on ammonioalkyl derivatives of crown ether styryl dyes.

Inhibitory effect of synthetic aromatic heterocycle thiosemicarbazone derivatives on mushroom tyrosinase: Insights from fluorescence, 1 H NMR titration and molecular docking studies

“…1 H NMR titration is a useful method to identify interaction between different molecules by determining chemical shift of hydrogen atoms (Gromov et al, 2014;Liu et al, 2015). The interactions between compounds 1a-3a and tyrosinase were further observed from 1 H NMR titrations in DMSO-d 6 .…”

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

“…Our previous investigations [3][4][5][6][7]17,18,28,45,46 have shown that brightly colored protonated styrylheterocycles and quaternary salts of styrylheterocycles (styryl dyes) Het + -CHCH-Ar X − (X − = I − , ClO 4 − , BF 4 − , TsO − ) are very suitable species for studying PCA reaction in the solid state, including the "single crystal-to-single crystal" (SCSC) processes (i.e., the processes that proceed without single crystal destruction). First their advantage is the potential to create the stacking packing motifs 1 or 2, and the rarely parallel-dimeric motifs 3 or 4.…”

“…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.…”

Novel Linear Bis-Crown Receptors with Cross-Conjugated and Conjugated Central Cores

“…[4][5][6][7][8][9] The most peculiar photochemical processes taking place in these supramolecular systems with significant changes in the properties are trans-cis-photoisomerization and [2+2]-photocycloaddition (PCA) reactions. [10][11] Consequently, it is possible to control the receptor properties of bis-crown ethers through photochemical modification of the labile central moiety.…”