Bathochromic Shift of Fluorescence Peak in Dipyrrolo[1,2-:2',1'-]quinoxaline by Introducing Each of Electron-Donating and Electron-Withdrawing Substituent.

Development of organic fluorophore is an important theme. Especially, the fluorophores with longer fluorescence peaks are useful to biological probes. One of the methods to change the fluorescence peak is the introduction of substituents.

Selective Formation of Internal Olefinic Trimer of α-Methylstyrenes with HI Gas and Ketones.

Reaction of α-methylstyrene in the presence of HI gas and methyl -tolyl ketone selectively resulted in an internal olefinic trimer. We revealed that the ketones with the stabilization of the protonated state were efficient to give the corresponding trimers, whereas the other ketones gave the usual indane compound. From the investigation for the mechanistic path, we found that the trimer is a kinetic product and that indane is a thermodynamic product.

Preparation of chiral 3-oxocycloalkanecarbonitrile and its derivatives by crystallization-induced diastereomer transformation of ketals with chiral 1,2-diphenylethane-1,2-diol.

Chiral 3-oxocycloalkanecarbonitriles were prepared by fractional crystallization and crystallization-induced diastereomer transformation (CIDT) of diastereomeric ketals with (1,2)-1,2-diphenylethane-1,2-diol. Investigation of the crystal structures by X-ray diffraction analysis revealed that the difference in hydrogen bonds caused the discrepancy of the solubilities between () and () diastereomers. Furthermore, CIDT to afford the ()-diastereomer in good yield (95% yield) and with high diastereoselectivity (97% de) was accomplished, which is the first example of CIDT of neutral compounds formation of the diastereomeric ketal with (1,2)-1,2-diphenylethane-1,2-diol.

Incrementing Stokes Shifts through the Formation of 2,2'-Biimidazoldiium Salts.

The formation of biimidazoldiium structures by the introduction of methyl substituents on the N atoms at the 3 and 3' positions of 2,2'-biimidazoles led to increments in the Stokes shift of these structures. Based on time-dependent density functional theory (TDDFT) calculations, the imidazolium rings become distorted and the N atoms of the imidazolium rings underwent structural changes through sp to sp rehybridization in the excited states.

CH/π Interactions for Macroscopic Interfacial Adhesion Design.

Adhesion to chemically inert materials without surface modification through noncovalent interactions represents a challenging task in adhesion science. We successfully develop for the first time a strategy utilizing multiple CH/π interactions that use poly(methacrylate) with an aromatic group (H acceptor) in the ester part and polyolefin materials (H donor). The strength increases with the number of π electrons and aromatic rings.

Formation of Benzimidazoisoquinolinium and Benzimidazoisoindolinum Cyclic Systems by the Reaction of 2-(2-Alkynylphenyl)benzimidazoles with Iodine and Iodine-Iodine Interaction Including Halogen Bonding in Their Crystal Structures.

The reaction of 2-(2-alkynylphenyl)benz[d]imidazoles with molecular iodine constructed 5- and 6-membered rings as novel organic salts in high yield. The constituted number of ring systems was influenced by the substituent at the triple bond: 6-membered rings were formed from compounds bearing aryl substituents, whereas 5-membered ones were obtained from compounds with hydrogen or alkyl substituents. The products were obtained with triiodide as a counteranion; however, compounds with iodide were also obtainable under certain conditions.

Fluorescence of diimidazo[1,2-a:2',1'-c]quinoxalinium salts under various conditions.

The synthesis and photophysical properties of diimidazo[1,2-a:2',1'-c]quinoxalinium salts were examined for different counteranions. The ethyl-substituted diimidazo[1,2-a:2',1'-c]quinoxalinium salt with tosylate anion (categolized in ionic liquid) showed good fluorescence (ΦF = 0.77) in organic solvent.

α-Diketone formation accompanied by oxidation of sulfur functional group by the reaction of o-alkynylarenesulfoxide with iodine.

The reaction of o-alkynylarenesulfoxide with iodine was investigated in detail, revealing functionalities of the formation of α-diketones with sulfenyl, sulfinyl, and sulfonyl. Additives can change the ratio of products to give medium-to-excellent yields. Results show that water is taken into only sulfonyl compound and that other oxygen atoms constructed in the products are presumably derived from sulfoxide of the starting material and molecular oxygen.

Novel formation of diimidazo[1,2-a:2',1'-c]quinoxaline derivatives and their optical properties.

Reaction of 1,2-di(imidazolyl)benzene treated with n-BuLi proceeded to give diimidazo[1,2-a:2',1'-c]quinoxaline in the presence of iodine or Pd(PPh(3))(4). Blue fluorescence was observed from 3,10-diarylated diimidazoquinoxalines with high quantum yield. They were also applied to organic light-emitting devices as emitters, in which the diphenyl derivative emits a nearly pure blue light.

Synthesis and C(2) -symmetric structure of a cyclotetrapeptide composed of anthranilic acid and leucine.

A chiral cyclotetrapeptide (1) was synthesized from 2-nitrobenzoic acid and leucine. A single-crystal X-ray of the compound revealed a C(2) -symmetric bowl-shaped structure. The cyclic compound had a unique hydrogen-bonding network composed of three-centered hydrogen bonds and bifurcated hydrogen bonds between NH and CO of anthranilic residue.

Predominant (S)-enantioselective inclusion of aryl methyl sulfoxides by (S)-isoleucyl-(S)-phenylglycines.

In terms of chiral recognition for racemic aryl methyl sulfoxides in the solid state, three kinds of crystalline (S)-alkylglycyl-(S)-phenylglycines were examined as potential dipeptides host molecules. When (S)-alanyl-(S)-phenylglycines [(S,S)-Ala-Phg] crystallized with aryl methyl sulfoxides, the stereochemistry of preferentially included sulfoxides depended on the individual shapes of the sulfoxides and the enantiomeric excess was relatively low. Although (S)-leucyl-(S)-phenylglycines [(S,S)-Leu-Phg] and (S)-isoleucyl-(S)-phenylglycines [(S,S)-Ile-Phg] mainly included the S-form of aryl methyl sulfoxides, the enantiomeric recognition of (S,S)-Ile-Phg was superior to that of (S,S)-Leu-Phg.

Novel synthesis of alpha-trifluoromethylated alpha-amino acid derivatives from gamma-hydroxy-alpha-fluoro-alpha-trifluoromethyl carboxamides.

On treatment with an organoaluminum reagent such as trimethylaluminum or DIBAL-H, gamma-hydroxy-alpha-fluoro-alpha-trifluoromethyl carboxamides (1) give a single diastereomer of alpha-amino-alpha-trifluoromethyl-gamma-lactones (2), which are a ring-closed form of gamma-hydroxy-alpha-trifluoromethyl-alpha-amino acids. This intriguing reaction results from intramolecular replacement of the fluorine atom on the alpha-carbon atom with the nitrogen atom of the amide group, which occurs in an SN2 manner. [reaction: see text]

Formation of gold-like metal-lustrous inclusion crystals from 1-phenyl-2,5-bis[5-(tricyanoethenyl)-2-thienyl]pyrrole host and an electron-donating aromatic guest.

A novel pi-conjugated organic compound, 1-phenyl-2,5-bis[5-(tricyanoethenyl)-2-thienyl]pyrrole, which bears two powerful electron-withdrawing tricyanoethenyl substitutents, readily yielded gold-like metal-lustrous inclusion crystals with a series of aromatic guest molecules such as toluene, p-xylene, anisole, dimethoxybenzenes and indene. All the inclusion compounds have a common stoichiometric ratio (host/guest) of 2 : 1. X-Ray structural analyses demonstrate that the structural feature for toluene included crystal is similar to those containing p-xylene, anisole, dimethoxybenzenes and indene.

Sheet structure of an L,D-dipeptide aggregate: inclusion compounds of (S)-phenylglycyl-(R)-phenylglycine with amides.

A simple dipeptide, (S)-phenylglycyl-(R)-phenylglycine (S,R-1), formed inclusion compounds with a small amide such as formamide, acetamide, N,N-dimethylformamide (DMF), or N,N-dimethylacetamide. By single-crystal X-ray analysis, the inclusion compounds were shown to have a wavy layer structure. The molecules of S,R-1 are arranged in parallel via ionic pairing of the carboxyl and amino groups to construct the wavy layers.