Supramolekulare Chemie von gespannten Kohlenstoffnanoreifen

Abstract

Seit 1996 ist eine stetig wachsende Anzahl von hoch gespannten Makrozyklen präparativ zugänglich geworden, die lediglich sp2‐ oder sp‐hybridisierte Kohlenstoffatome im Ring enthalten, wobei [n]Cycloparaphenylenacetylene (CPPAs) und [n]Cycloparaphenylene (CPPs) die wichtigsten Beispiele dieser Klasse darstellen. Nachdem nun robuste und relativ allgemeine Synthesewege zu einer Vielzahl von Nanoreifen‐Strukturen zur Verfügung stehen, beginnt sich der Forschungsschwerpunkt auf die Erforschung ihrer Eigenschaften und Anwendungen zu verlagern. Aus Sicht der supramolekularen Chemie bieten diese Makrozyklen wegen ihrer nahezu perfekten Kreisform, der ungewöhnlich hohen Formstabilität und der Gegenwart von konvexen und konkaven π‐Flächen einzigartige Möglichkeiten. In diesem Kurzaufsatz besprechen wir den Einsatz von gespannten kohlenstoffreichen Nanoreifen in der Wirt‐Gast‐Chemie, der Herstellung von mechanisch verzahnten Architekturen und dem definierten Kristalldesign.

A Long‐Lived Azafullerenyl Radical Stabilized by Supramolecular Shielding with a [10]Cycloparaphenylene

“…Highly reactive C 59 NC radicals can be shielded by nesting them in carbon nanobelts consisting of single phenyl units connected in para position-cycloparaphenylenes (CPPs). [22][23][24] These convex molecules have been explored for fullerene complexation and the study of photoinduced phenomena. [25][26][27][28][29][30][31] Our approach takes advantage of 1) the 1.4 nm cavity of [10]CPP, resembling the inner space of carbon nanotubes favoring p-p host-guest interactions,t oa ccommodate aC 59 NC radical (Figure 1a), 2) the diminished environmental exposure of the radical resulting from the favorable orientation of the CPPs close to the exposed radical, and 3) the well-established chemistry of C 59 NC,w hich prevents chemical addition to 1,4substituted phenylenes because of steric hindrance.…”

Conjugated Nanohoops with Dibenzo[a,e]pentalenes as Nonalternant and Antiaromatic π-Systems

“…With their circular shape and their large π-surface, conjugated nanohoops are ideally suited for binding guest molecules such as fullerenes. 4 86 Of the DBP-hoops discussed here, we investigated the host–guest chemistry of [4]CDBP 3 16 and [6]DBP[4]Ph (+)- 12 . 14 With a diameter of 13 Å, 3 can perfectly host both spherical C 60 (mean diameter: 7.1 Å) and American-football-shaped C 70 (short axis: 7.12 Å; long axis: 7.96 Å).…”

“…1 Among their most interesting properties are their cyclic conjugation and radially oriented π-systems, their size-dependent optoelectronic properties, 2 and their ability to act as host–guest molecules. 3 4 Due to the cyclic structure of carbon nanohoops, their π-systems are bent, which changes their optoelectronic and other properties. Although they were proposed as attractive synthetic targets as early as 1934, 5,6 only in the past 13 years have synthetic advances led to syntheses of a plethora of different carbon nanohoop structures 7 and architectures.…”

The Aggregation Regularity Effect of Multiarylpyrroles on Their Near‐Infrared Aggregation‐Enhanced Emission Property

“…[17][18][19][20] For example, Tang and his co-workers used triphenylamine as ad onor and ap yridine salt derivativea sa na cceptor to synthesize three NIR molecules with targeting effects for synergistic photodynamic therapy,a chieving the 1 + 1 + 1 > 3e ffect. [21] Ding's group reported as eries of AIE dyes in the NIR region using 2-(4-pyridin-4-ylphenyl) acetonitrile as ar eceptor and triphenylamine and benzene as donors and then added tetraphenylethylene (TPE) units in the donorp art to increase the degree of molecular distortion to reduce intermolecular interactions and to increase reactiveo xygen species (ROS) production. [22,23] Ajayaghosh et al designed aseries of diketopyrrolopyrrole-based NIR absorption or emissiono ptoelectronic functional materials by D-A strategy.…”