Per-Substituted [8]Circulene and Its Non-Planar Fragments: Synthesis, Structural Analysis, and Properties.

The syntheses, structures, and physical properties of a full series of benzannulated tetraphenylenes are reported. The palladium-catalyzed annulation of tetraiodo-substituted 2,3,6,7,10,11,14,15-octamethyltetraphenylene with insufficient di(4-anisyl)ethyne yielded a mixture of per-substituted [8]circulene and its non-planar fragments, including mono-, para-di-, ortho-di-, and triannulated products. Their structures were unambiguously verified by X-ray crystallography. Successive benzannulations significantly affect the molecular geometries, dynamic behaviors, and physical properties of the compounds. In this series of compounds, [8]circulene is the most strained one, as reflected by the significant deplanarization of the phenanthrene moieties (ca. 63° in the bay region) and the fact that it has the highest strain energy (120.6 kcal mol(-1) ). The dynamic behaviors of these compounds were examined both experimentally and theoretically. The ring flipping of per-substituted [8]circulene is confirmed to proceed through pseudorotation with a barrier of around 21 kcal mol(-1) , whereas its non-planar fragments require much more energy for the ring inversion. The photophysical and electrochemical properties of the investigated compounds depend strongly on the extent of efficient π conjugation. The successive benzannulations red-shift both the absorption and the emission bands, and reduce the first oxidation potential.

Palladium-catalyzed annulation of 9-halophenanthrenes with alkynes: synthesis, structural analysis, and properties of acephenanthrylene-based derivatives.

The palladium-catalyzed annulation of 9-bromo- and 9-chlorophenanthrenes with alkynes gave 4,5-disubstituted acephenanthrylenes in yields of 58-95% (9 examples). Asymmetric alkynes, such as 1-phenyl-1-propyne, 1-phenyl-1-hexyne, and 1-cyclopropyl-2-phenylethyne, regioselectively form (cyclo)alkyl-substituted products, following the regular rule that governs the carbopalladation of alkynes. This synthetic protocol can also be utilized in annulations with several π-extended bromoarenes, such as 7-bromo[5]helicene, 5-bromo[4]helicene, 9-bromoanthracene, 3-bromoperylene, and 3-bromofluoranthene, to give the corresponding annulated products in moderate to good yields (51-86%; 6 examples). Similarly, bromocorannulene produced highly curved 1,2-disubstituted cyclopentacorannulenes. Reactions of 6,12-dibromochrysene and 4,7-dibromo[4]helicene with di(4-tolyl)ethyne provided the twofold annulated products in moderate yields. 4,5-Diphenylacephenanthrylene and 6,7-diphenylbenzo[a]acephenanthrylene thus generated were converted into phenanthro[9,10-e]acephenanthrylene and benzo[a]phenanthro[9,10-e]acephenanthrylene, respectively, by oxidative cyclodehydrogenation. The structures of 4,5-diphenylacephenanthrylene, 4,5-diphenyldibenzo[a,l]acephenanthrylene, 1,2-diarylcyclopentacorannulenes, and benzo[a]phenanthro[9,10-e]acephenanthrylene were verified by X-ray crystallography. The photophysical and electrochemical properties of the selected annulated products were investigated.

Secondary special educators' transition involvement.

BACKGROUND: Different roles and responsibilities are required of school professionals to facilitate students' successful transition from school to post-school lives. Special educators' involvement in transition services is essential for better post-school outcomes for students with disability. METHOD: The Transition Involvement Survey with five domains was developed for the study and a total of 343 secondary special educators in the United States participated. MANOVA and post hoc discriminant analysis were used to examine group differences across the five domains. RESULTS: Special educators rated highly in their involvement in transition planning but less so in other domains. Receiving in-service training was significantly related to educators' transition involvement but receiving pre-service training was found to be only partly related. CONCLUSION: The gap between special educators' knowledge and involvement in extending transition services affects the provision of services. Recommendations from this study support stronger personnel preparation to improve this situation.

Rotation of Aryl Groups in 9,10-Diarylphenanthrenes: Does the Rotational Barrier Become Lower as the Backbone Becomes More Crowded?

A series of 9,10-diarylphenanthrenes was prepared, and their structures and dynamic behaviors were both theoretically and experimentally investigated. A more twisted and crowded phenanthrene backbone was associated with a lower barrier to the rotation of an aryl group.

Dinaphthozethrene and Diindenozethrene: Synthesis, Structural Analysis, and Properties.

Zethrene-based condensed arenes dinaphthozethrene and diindenozethrene were synthesized by oxidative cyclodehydrogenation and palladium-catalyzed cyclization of 7,14-diarylzethrenes, respectively. Their structures were analyzed by X-ray crystallography. The photophysical and electrochemical properties of these compounds were investigated.