Spectroscopic studies of β-cyclodextrin-complexed cyanine dyes

π-Stacked and unstacked aggregate formation of 3,3′-diethylthiatricarbocyanine iodide, a near-infrared dye

3,3′-Diethylthiatricarbocyanine iodide (DTCI) emits distinctive monomer and dimer emissions whose intensity ratio varied depending on concentration in methanol and water.

A simple protocol for the visual discrimination of natural cyclodextrins in aqueous solution using perichromic probes

Three synthesized compounds, 4-(4-nitrostyryl)phenol, 2,6-dibromo-4-(2,4-dinitrobenzylideneamino)phenol and 2,6-dichloro-4-(2,4-dinitrobenzylideneamino)phenol, were deprotonated to generate the perichromic dyes 2b, 3b and 4b, respectively. These dyes were used as probes to investigate the micropolarity of natural cyclodextrins (CyDs) and it was observed that they interact differently with the CyDs according to the molecular structure of the dye and the diameter of the CyD. The solvatochromic bands of the dyes that interacted with the CyDs were bathochromically shifted, suggesting that the probes were transferred to the hydrophobic interior of the CyD in aqueous solution. Dyes 2b and 4b were found to be very selective for α-CyD and γ-CyD, respectively, while β- and γ-CyD changed the color of the solution of compound 3b. These dyes were then successfully used in a simple assay that allows the naked-eye discrimination of natural CyDs in aqueous solution, without the need for expensive techniques.

Calix[4]arene sulfonate as a template for forming fluorescent thiazole orange H-aggregates

The unexpected interaction between thiazole orange (TO) and calix[4]arene sulfonate is reported herein. H-Aggregates of TO switching on their fluorescence in solution are observed. Surprisingly, fluorescence enhancement is not linked to host-guest inclusion, but rather to calix[4]arene sulfonate serving as a template for several TO molecules.