Non-aqueous capillary electrophoresis of p-quinone anion radicals.

The electrophoretic detection of two kinds of p-quinone anion radicals arising from the electrolysis of benzoquinone and chloranil was achieved by employing an acetonitrile medium. Sufficient dehydration of a running solution was necessary for the detection of the benzoquinone anion radical. Oxygen in the running solution also caused a serious decrease in the amount of the benzoquinone anion radical during electrophoresis. The addition of methanol as a hydrogen-donor decreased the electrophoretic mobility of the benzoquinone anion radical significantly, while that of the chloranil anion radical was little changed. This result is interpreted in terms of hydrogen-bonding interaction between the p-quinone anion radicals and methanol, reflecting the magnitude of their proton-accepting ability (benzoquinone anion radical > chloranil anion radical).     

Highly Pure Synthesis,Spectral Assignments,and Two‐Photon Properties of Cruciform Porphyrin Pentamers Fused with Benzene Units

Tetrameric porphyrin formation of 2‐hydroxymethylpyrrole fused with porphyrins through a bicyclo[2.2.2]octadiene unit gave bicyclo[2.2.2]octadiene‐fused porphyrin pentamers. Thermal conversion of the pentamers gave fully π‐conjugated cruciform porphyrin pentamers fused with benzene units in quantitative yields. UV/Vis spectra of fully π‐conjugated porphyrin pentamers showed one very strong Q absorption and were quite different from those of usual porphyrins. From TD‐DFT calculations, the HOMO level is 0.49 eV higher than the HOMO?1 level. The LUMO and LUMO+1 levels are very close and are lower by more than 0.27 eV than those of other unoccupied MOs. The strong Q absorption was interpreted as two mutually orthogonal single‐electron transitions (683 nm: 86 %, HOMO→LUMO; 680 nm: 86 %, HOMO→LUMO+1). The two‐photon absorption (TPA) cross section value (σ⁽²⁾) of the benzene‐fused porphyrin pentamer was estimated to be 3900 GM at 1500 nm, which is strongly correlated with a cruciform molecular structure with multidirectional π‐conjugation pathways.     

1,21‐Henicosanediol

In the molecular structure of the title compound, C₂₁H₄₄O₂, the hydro­carbon skeleton has an all‐trans conformation. One of the terminal hydroxyl groups is also trans with respect to the skeleton, while the other is gauche. In the crystal structure, the mol­ecules lie parallel to the b axis, forming layers with a thickness of b/2. The packing is similar to that in the smectic A phase of liquid crystals. These features are similar to those of the homologues with an odd number of C atoms, but different from those with an even number.     

A note on chordal bound graphs and posets

We study relations between induced subgraphs and (n,m)-subposets. Using properties of (n,m)-subposets, we consider a characterization of chordal double bound graphs in terms of forbidden subposets. Furthermore, we deal with properties of a poset whose double bound graph is isomorphic to its upper bound graph or its comparability graph, etc.     

Über die charakteristischen Untergruppen einer endlichen Abelschen Gruppe

Ohne Zusammenfassung     

On double bound graphs and forbidden subposets

For a poset P=(X,≤_P), the double bound graph (DB-graph) of P is the graph DB(P)=(X,E_DB(P)), where xy∈E_DB(P) if and only if x≠y and there exist n,m∈X such that n≤_Px,y≤_Pm. We obtain that for a subposet Q of a poset P,Q is an (n, m)-subposet of P if and only if DB(Q) is an induced subgraph DB(P). Using this result, we show some characterizations of split double bound graphs, threshold double bound graphs and difference double bound graphs in terms of (n, m)-subposets and double canonical posets.     

Effective synthesis of diiodinated picene and dibenzo[a,h]anthracene by AuCl-catalyzed double cyclization

6,13-Diiododibenzo[a,h]anthracene and 5,8-diiodopicene were synthesized by AuCl-catalyzed double cyclization. The highly selective reaction yielded a new class of peri-halogenated fused aromatics.     

A modular approach to a new class of phosphinohydrazones and their use in asymmetric allylic alkylation reactions

A group of five phosphino hydrazones with a pendant binaphthyl unit as a chiral modifier has been synthesized from non-racemic 2,2′-bis(bromomethyl)-1,1′-binaphthyl and 3,3′-diiodo-2,2′-bis(bromomethyl)-1,1′-binaphthyl as the key intermediates. Their efficiency as chiral ligands in palladium-catalyzed allylic alkylation reactions has been investigated showing up to 95% ee under optimized conditions. X-ray diffraction structures of mono- and dimeric Pd complexes are also reported.