A water soluble pentacene, potassium 3,3′-(pentacene-6,13-diylbis(sulfanediyl))dipropanoate (4), has been synthesized and characterized. The synthesis of 4 is straightforward and scalable, and its isolation does not require time consuming chromatographic separations. UV-vis spectra in several solvents indicate an optical HOMO–LUMO gap of approximately 1.91–1.97 eV. Water soluble pentacene 4 is long-lived in the solution phase and in the solid state. Because it forms stable solutions, inks based on 4 have been formulated and printed onto paper and flexible plastic using an unmodified commercial ink-jet printer. A bi-layer photovoltaic cell using 4 as donor and [60]fullerene as acceptor was fabricated and shown to be active. The crystal structure of the pentacene diacid precursor to water soluble pentacene 4 has been solved and shows a parallel displaced arrangement of pentacene rings, indicative of stabilizing π–π stacking interactions. DFT modeling for 4, however, suggests an unusual, low energy conformation in which both potassium carboxylate moieties are located on the same face (syn) of the pentacene π system. Likewise, calculated two-molecule stacks of 4 suggest a crystal packing arrangement in which potassium carboxylate moieties are intercalated between adjacent pentacene rings.

Several o-quinodimethane adducts of [60]fullerene were synthesized and their intramolecular aryl CH–fullerene π interactions were studied using variable temperature-NMR (VT-NMR). Evaluation of the rate constants associated with the first-order transition states for cyclohexene boat-to-boat inversions enables quantification of ΔG⧧ values for each inversion. A comparison between two constitutional isomers, only one of which is capable of intramolecular CH−π interactions, provides a lower limit of 0.95 kcal/mol for each aryl CH–fullerene π interaction.

A significant technical barrier (i.e., facile oxidative degradation) that has prevented the preparation of large acenes has now been breached. Using a combination of experimentally and theoretically derived substituent effects, the design, synthesis, isolation, and characterization of the first persistent nonacene derivative is described. The molecular design strategy includes placement of arylthio (or alkylthio) substituents on the terminal rings of the nonacene skeleton, effectively converting an open-shell singlet diradical into a closed-shell system. These powerful substituent effects appear to be suitable for the synthesis of other persistent, soluble, large acene derivatives required for advanced thin-film organic semiconductor applications.

The Diels–Alder cycloadditions of [60]fullerene across sterically hindered 6,13-bis(2′,6′-dialkylphenyl)pentacenes, 1 and 2, produce fullerene–acene monoadducts 3 and 4. In both cases, further [60]fullerene cycloaddition to form cis-bis[60]fullerene adducts is retarded by steric resistance between the [60]fullerene moieties and the o-dialkyl substituents. Instead, the fullerene moieties of monoadducts 3 and 4 sensitize the formation of 1O2 which subsequently cycloadds across the acene backbone to produce novel syn and anti [60]fullerene–dioxo bisadducts, 8–11.

All fullerenes including [60]fullerene, [70]fullerene and giant fullerenes are hydrogenated in excellent yield using polyamines like diethylenetriamine (DET), triethylenetetramine (TET), tetraethylenepentamine (TEP) or pentaethylenehexamine (PEH) at elevated temperatures. The resulting hydrogenated fullerenes or fulleranes have been characterized by a combination of NMR spectroscopy and mass spectrometry. The addition of elemental cobalt promotes formation of more highly hydrogenated fulleranes. Hydrogenation reaction times can be reduced to minutes using a microwave reactor. The mechanism of polyamine hydrogenation is discussed in terms of successive electron transfer–protonation cycles as evidenced by deuterium labeling studies.

A water soluble pentacene, potassium 3,3′-(pentacene-6,13-diylbis(sulfanediyl))dipropanoate (4), has been synthesized and characterized. The synthesis of 4 is straightforward and scalable, and its isolation does not require time consuming chromatographic separations. UV-vis spectra in several solvents indicate an optical HOMO–LUMO gap of approximately 1.91–1.97 eV. Water soluble pentacene 4 is long-lived in the solution phase and in the solid state. Because it forms stable solutions, inks based on 4 have been formulated and printed onto paper and flexible plastic using an unmodified commercial ink-jet printer. A bi-layer photovoltaic cell using 4 as donor and [60]fullerene as acceptor was fabricated and shown to be active. The crystal structure of the pentacene diacid precursor to water soluble pentacene 4 has been solved and shows a parallel displaced arrangement of pentacene rings, indicative of stabilizing π–π stacking interactions. DFT modeling for 4, however, suggests an unusual, low energy conformation in which both potassium carboxylate moieties are located on the same face (syn) of the pentacene π system. Likewise, calculated two-molecule stacks of 4 suggest a crystal packing arrangement in which potassium carboxylate moieties are intercalated between adjacent pentacene rings.

All fullerenes including [60]fullerene, [70]fullerene and giant fullerenes are hydrogenated in excellent yield using polyamines like diethylenetriamine (DET), triethylenetetramine (TET), tetraethylenepentamine (TEP) or pentaethylenehexamine (PEH) at elevated temperatures. The resulting hydrogenated fullerenes or fulleranes have been characterized by a combination of NMR spectroscopy and mass spectrometry. The addition of elemental cobalt promotes formation of more highly hydrogenated fulleranes. Hydrogenation reaction times can be reduced to minutes using a microwave reactor. The mechanism of polyamine hydrogenation is discussed in terms of successive electron transfer–protonation cycles as evidenced by deuterium labeling studies.