An unexpected two-group migration involving a sulfonynamide to nitrile rearrangement. Mechanistic studies of a thermal N --> C tosyl rearrangement.

We report the discovery of the first double-barreled thermal rearrangement of a sulfonynamide and a methoxybenzyl to a nitrile and the first rearrangement of an SO(2) group from sulfonamide to ketoimine. The rearrangement occurs under surprisingly mild conditions (onset at 100 degrees C in the melt). [reaction: see text]

Efficient synthesis of a novel, twisted and stable, electroluminescent "twistacene".

[reaction: see text] A twistacene, 6,8,15,17-tetraphenyl-1.18,4.5,9.10,13.14-tetrabenzoheptacene (3), was synthesized using a mild and novel bisbenzyne precursor. It was characterized by X-ray crystallography, NMR, UV-vis, and IR spectroscopies, as well as cyclic voltammetry and DFT calculations. The heptacene derivative possesses a nonpropeller twist topology and is unusually stable for a highly conjugated oligoacene. In addition, it is fluorescent, with a quantum efficiency of 15%. Distortion from planarity, mostly due to the phenyl substituents, causes only marginal changes in electronic properties and is beneficial for redox reversibility, which is required for efficient OLED devices.

Photochemical preparation of 1,3,5,7-tetracyanoadamantane and its conversion to 1,3,5,7-tetrakis(aminomethyl)adamantane.

New adamantane derivatives 1 and 2 that bear functionalized one-carbon extensions at all four bridgehead positions have been prepared. Radical nucleophilic substitution (S(RN)1) reaction of 1,3,5,7-tetrabromoadamantane with cyanide produces 1,3,5,7-tetracyanoadamantane (1), which was reduced with borane reagents to 1,3,5,7-tetrakis(aminomethyl)adamantane (2). Improvements in the preparation of 1,3,5,7-tetrahaloadamantanes (halogen = Br, Cl, I) are also reported. [structure--see text]

Approaching a stable, green twisted heteroacene through "clean reaction" strategy.

A new, longest, stable, green twisted heteroacene 2-methyl-1,4,6,13-tetraphenyl-7:8,11:12-bisbenzo-anthro[g]isoquinolin-3(2H)-one (3) was synthesized by employing a "clean reaction" strategy based on thermally eliminating lactam bridges. Calculation shows that the HOMO-LUMO bandgap is in good agreement with experimental data.

Synthesis, characterization, and physical properties of a conjugated heteroacene: 2-methyl-1,4,6,7,8,9-hexaphenylbenz(g)isoquinolin-3(2H)-one (BIQ).

We report the synthesis and characterization of a novel, stable and blue heteroacene, 2-methyl-1,4,6,7,8,9-hexaphenylbenz(g)isoquinolin-3(2H)-one (BIQ 3). BIQ 3, with its relatively small π framework, has an absorption λ(max) at 620 nm, which is larger than that of pentacene (λ(max) = 582 nm), but BIQ 3 is more stable. The solutions of BIQ 3 are observed without any noticeable photobleaching on the order of days. In the solid state, it is very stable at ambient conditions and can be stored indefinitely. Owing to its pyridone end unit, BIQ 3 can display different resonance structures in different solvents (aprotic and protic) or Lewis acids to give different colors. The attractive stability exhibited by BIQ 3 is very desirable in organic semiconductor devices. Herein, we investigated a simple heterojunction photovoltaic device based on BIQ 3 as an electron donor and [6,6]-phenyl-C(61) butyric methyl ester as an electron acceptor. Our results show that this type of heteroacene could be a good candidate as a charge-transport material in organic semiconductor devices.

Novel reversible ionic-to-covalent transition in a highly conducting TTF derivative.

TTF produces two completely different phenomena with the different isomers of chloranil; with the para isomer it produces an insulating, alternating stack, ambient temperature neutral solid. While with the ortho isomer, it produces a more interesting system consisting of interconvertible conducting ionic and covalent components.

Oligoacenes: theoretical prediction of open-shell singlet diradical ground states.

A series of oligoacenes from benzene to decacene were studied computationally with DFT and CASSCF methods. In contrast to the common view that acenes are closed-shell systems or may have a triplet ground state, these results offer the first theoretical predictions for the singlet ground state and diradical character for oligoacenes. The nature of the ground states of these molecules arises from the disjoint nature of the NBMOs that are singly occupied in the diradical.