Ultrastable Rhodamine with Cucurbituril

Abstract

Rhodamines are arguably the most important fluorescent dyes as shown by their classical and contemporary applications, [1][2][3][4][5][6][7][8] for example, in dye lasers, as quantum counters, as photosensitizers, for spectral calibration in fluorometers, in single-molecule detection, as imaging agents for biomolecules, for scanning confocal microscopy, in fluorescence correlation spectroscopy (FCS), and in high-throughput screening assays. The various applications are made possible through the combination of their water solubility, close-tounity quantum yields, high extinction coefficients, and very high photostability. Rhodamine 6G (Rh6G) is the most prominent derivative and has become a prototype for many reasons, [3,4] including its photostability: the first continuouswave dye laser, for example, was based on an aqueous solution of Rh6G containing 1.5 % triton X as surfactant.[9]

Specific Binding Effects for Cucurbit[8]uril in 2,4,6‐Triphenylpyrylium–Cucurbit[8]uril Host–Guest Complexes: Observation of Room‐Temperature Phosphorescence and their Application in Electroluminescence

“…[1][2][3][4][5][6] Substituted pyrylium ions have been widely used as photosensitizers in photoinduced electron transfer and as sensors. [18][19][20][21][22][23][24][25][26][27][28] Given the related precedent for a remarkable increase in the photostability of Rhodamine 6G upon encapsulation in CB [7], [29][30] it is of interest to determine the properties of the resulting host-guest complex with pyrylium ions, particularly to put the behavior of these inclusion complexes into context with those reported for related supramolecular systems that contain pyrylium ions. [18,20,23,25,28,[31][32][33][34][35][36] Herein we report the unique features exhibited by the 2,4,6-triphenylpyrylium ion (TP + ) upon encapsulation in CB [8].…”

Control of the Supramolecular Excimer Formation of Thioflavin T within a Cucurbit[8]uril Host: A Fluorescence On/Off Mechanism

“…In our recent study on ThT interaction with cucurbit [5]uril (CB5) and cucurbit [7]uril (CB7), it was seen that interaction with CB7 leads to the formation of 1:1 and 2:1 (CB7-ThT) inclusion complexes, whereas, CB5 prefers an exclusion complex formation due to its smaller cavity size. [24] In both cases, ThT displayed emission enhancement over its 490 nm spectral band to % 30 fold and % 5 fold for CB7 and CB5, respectively.…”

Photoreversible Fluorescence Modulation of a Rhodamine Dye by Supramolecular Complexation with Photosensitive Cyclodextrin

“…The shift in fluorescence is not pronounced, which suggests that the relaxation of the dye through geometrical and solvent effects is smaller, as expected for inclusion in a less polar and more confined environment. [14] However, at the same concentration of RhB, the fluorescence intensity of the complex is stronger than that of a pure RhB solution, which is probably because the supramolecular complexation between RhB and CDSP-2 reduces the selfquenching of RhB resulting from self-aggregation. A widely used method [21] was employed to determine the complexation stoichiometry, and a complexation ratio of 1:1 for RhB and CDSP-2 was found (see the Supporting Information).…”

“…[14,15] Herein, we synthesized photosensitive cyclodextrin (CDSP) by covalently attaching spiropyran moieties onto b-CD. Rhodamine B [16][17][18] (RhB) was used as a model fluorophore to form a supramolecular complex with the CDSP, and photoreversible fluorescence modulation was thus realized.…”