Belt-, ball-, and tube-shaped molecules

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 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).…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Among the different organic capsules, cucurbiturils (CBs) have specific structural features that arise from the polarity of the entrances, which is controlled by the presence of negative carbonyl oxygen atoms, their ability to bind positively charged organic guests, and their barrel shape, which is able to immobilize guests in the interior that are larger than the size of the portals. [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.…”

Size‐Selective Encapsulation of C60 by [10]Cycloparaphenylene: Formation of the Shortest Fullerene‐Peapod

“…Owing to their unique structures, CPPs have attracted the attention of theoretical, synthetic, and supramolecular chemists for more than half a century. [1][2][3][4][5][6] Based on the analogy to layered carbon networks with curved surfaces, for example multiwalled carbon nanotubes, [7,8] bucky onions, [9,10] and fullerene-peapods, [11][12][13] the concave cavity of the CPPs should act as a host for pconjugated molecules with a convex surface, such as fullerenes. Such a host-guest complex would be a suitable model for elucidating convex-concave p-p interactions.…”

Ionophores and receptors using cation-π interactions: Collarenes

“…There have been reports of the systems in which -orbitals are oriented vertically to the plane of the rings, namely belt-shape carbocyclic-conjugated systems (such as annulenes, beltenes, cyclacenes, and collarenes) (28)(29)(30)(31)(32)(33)(34)(35)(36)(37). The recent discoveries of fully conjugated systems with a curved surface like fullerenes and carbon nanotubes (38,39) further adds fuel to such a kind of study.…”

“…The recent discoveries of fully conjugated systems with a curved surface like fullerenes and carbon nanotubes (38,39) further adds fuel to such a kind of study. However, belt-shape carbocyclic-conjugated systems have hardly been studied apart from the synthetic study of cyclacene precursors and collarenes (32)(33)(34)(35)(36)(37).…”