Molecular Recognition Abilities of a New Class of Water-Soluble Cyclophanes Capable of Encompassing a Neutral Cavity

Abstract

We developed a new class of water-soluble cyclophanes, pyrenophanes, capable of encompassing a neutral cavity, in which the hydrophobic area is constructed by aligning two flat polynuclear aromatic rings parallel at an appropriate space that could interpose just one layer of aromatic plane. The height, depth, and width of the cavity in an open conformation of the pyrenophane are 0.46, 0.95, and 1.31 nm, respectively, i.e., the area of this cavity is so large that even porphirin compounds might be incorporated. In the fluorescence spectra, the pyrenophanes showed only excimer-emission, reflecting the existence of two proximal pyrene rings. Treatment of the pyrenophanes with anionic and cationic aromatic compounds revealed the formation of complexes in the UV and fluorescence spectra, suggesting that the binding affinities of the pyrenophanes for aromatic compounds were mainly governed by hydrophobic and/or π-stacking interactions. The macrocyclic structures of the pyrenophanes were found to be indispensable for the complexation.

Artificial Receptors for the Recognition of Phosphorylated Molecules

“…205,206 In this case, preliminary studies with receptor 96a in 3:1 water:ethylene glycol revealed a change in the absorption spectrum upon the addition of a variety of guests, including nucleotide monophosphates AMP, UMP, GMP, and CMP. Among this latter class of substrates, a modest selectivity was observed for GMP ( K = 3.5 × 10 4 M -1 ).…”

Cyclophanes containing large polycyclic aromatic hydrocarbons

“…As before, a system with a 90° twist would have been a useful addition to this study. The (1,6)pyrenophanes 37a-p, 37 several of which are watersoluble, are the largest and most elaborate pyrenophanes to have been reported to date. These systems were designed to have moderately rigid, side-chain-bearing frameworks that would encompass a neutral cavity and thereby resemble the hydrophobic areas of double helical DNA for the purpose of recognizing planar (aromatic) molecules in water.…”

Synthesis of substituted pyrenes by indirect methods

“…[15][16][17] For example, poly( pyrenebutyric acid) has been used as a noncovalent stabilising unit for single-walled carbon nanotubes, preventing formation of bundles and enabling dispersion in solvents. 18 Pyrene has also found use in biological chemistry, especially in systems for binding nucleic acids, [19][20][21][22] and in the design of synthetic receptors for aromatic 23,24 and carbohydrate 25 substrates.…”