Phenyl Groups versus tert-Butyl Groups as Solubilizing Substituents for Some [5]Phenacenes and [7]Phenacenes

Abstract

In recent years, we have used the photocyclizations of diarylethylenes to synthesize a number of [n]phenacenes in the hope that they might be useful as the bridging groups for electron transfer processes in donor-bridge-acceptor molecules. Because [n]phenacenes with n > 5 are very insoluble, their synthesis and characterization has required the attachment of solubilizing substituents such as tert-butyl. The studies of Pascal and co-workers of some large polynuclear aromatic compounds having multiple phenyl substituents prompted us to explore the use of phenyls as alternative solubilizing groups for [n]phenacenes. Although phenyl groups turned out to provide significantly less solubilization than tert-butyl groups in these compounds, we found some interesting structural comparisons of the phenyl-substituted and tert-butyl-substituted [n]phenacenes.

Synthesis and transistor application of the extremely extended phenacene molecule, [9]phenacene

“…Therefore, to the best of our knowledge, the [9]phenacene synthesized in this study is the most extended phenacene molecule without substituents. The absence of substituents is important, as their presence on the phenacene core may produce a distorted framework rather than the planar structure 28 that is required for the formation of the π-electron network that is sought. It is thought that a sufficiently extended π-electron network may make high-channel transport available for high-speed transistors and high-efficiency optical absorption/emission for solar cells and light-emitting diodes.…”

Kinetic Control in the Regioselective Alkylation of Pterin Sensitizers: A Synthetic, Photochemical, and Theoretical Study

“…One reason the solubility enhancement is so beneficial is that the reactions of pterins are not amenable to common organic solvents and purification techniques. In addition to solubility enhancements, it is logical to suggest an increase in the pterins' resistance against forming of aggregates due to alkylation, similar instances of deaggregation of porphyrins and other aromatics due to alkylation in organic solvents (57)(58)(59)(60)(61)(62)(63)(64)(65). This decrease in aggregation has proven necessary to improve sensitizer performance (66)(67)(68).…”

Synthesis of Pinpoint‐Fluorinated Polycyclic Aromatic Hydrocarbons: Benzene Ring Extension Cycle Involving Microwave‐Assisted SNAr Reaction

“…In addition, the repulsive interaction between lone pairs in the fluorine 2p orbitals and the adjacent π electrons in the carbon 2p orbitals perturbs the electron density of the extended π systems, which would render these compounds highly soluble in polar organic solvents, leading to printable organic electronics . It is also worth mentioning the low steric impact of fluorine, whose introduction into PAH molecules should not change their molecular shape, would not significantly affect their π–π stacking in the solid structure . Therefore, the effects of installing a single fluorine substituent in PAH skeletons would lead to advantageous semiconducting materials, such as THF‐soluble fluorinated picenes, which exhibit p‐type semiconducting behavior…”

“…[4] It is also worth mentioning the low steric impact of fluorine, whose introduction into PAHm olecules should not change their molecular shape, would not significantly affect their p-p stacking in the solid structure. [5,6] Therefore, the effects of installing as ingle fluorine substituent in PAHs keletons would lead to advantageous semiconducting materials, such as THF-soluble fluorinated picenes, whiche xhibit p-type semiconducting behavior. [5,7] To facilitate the efficient synthesis of pinpoint-fluorinated PAHs, we have recently developed metal-catalyzed cyclizations of fluoroalkenes on the basis of the followingb enzene ring construction strategy (Scheme 1): (a) 1,1-difluoroallenes,r eadily prepared via difluorovinylidenation of aldehydes, [8] undergo a Friedel-Crafts-type cyclization in the presence of ac atalytic amount of indium(III) bromide.…”