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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

“…The remarkably high roomtemperature phosphorescence quantum yield of the TP + @CB [8] complex has been advantageously applied to develop an electroluminescent cell that contains this host-guest complex. In contrast, analogous cells prepared with TP + or TP + @CB [7] fail to exhibit electroluminescence. Keywords: cucurbiturils · electroluminescence · host-guest systems · phosphorescence · supramolecular chemistry [a] As expected in view of previous reports of encapsulating organic molecules inside CBs, [1,2,5] addition of increasing amounts of CBs to the aqueous solution of TP + produces changes in the absorbance spectrum.…”

“…[19,23,31,32,34,37,40,41] Upon addition of CB [5] and CB [6], very minor changes in fluorescence are recorded. In contrast, the presence of CB [7] causes a significant blueshift of l fl (10 nm). More relevant are the changes in the emission produced by the presence of CB [8].…”

“…[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].…”

“…1 H NMR spectroscopic data indicates that complexation takes place by encapsulation of the phenyl ring at the four position within CB. Formation of the complex with CB [6] and CB [7] leads to minor shifts in the fluorescence wavelength maximum (l fl ) or quantum yield (F fl ). In sharp contrast, for complexes with CB [8], the emission results in the simultaneous observation of fluorescence (l fl = 480 nm, F fl = 0.05) and room-temperature phosphorescence (l ph = 590 nm, F ph = 0.15).…”

“…Keywords: cucurbiturils · electroluminescence · host-guest systems · phosphorescence · supramolecular chemistry [a] As expected in view of previous reports of encapsulating organic molecules inside CBs, [1,2,5] addition of increasing amounts of CBs to the aqueous solution of TP + produces changes in the absorbance spectrum. These variations with respect to free TP + were relatively minor for CB [5], CB [6], and CB [7], for which small shifts in l max (about 10 nm) and some variations in the absorption coefficient were observed. More notable is the case of CB [8] whose presence led to a significant change in the values for l max , the extinction coefficient, and the full width at half height of the absorption bands.…”