Synthesis of π-Extended Carbazole Dimers Via Oxidative Cyclization Using DDQ and Sulfonic Acid and Elucidation of the Reaction Mechanism.

This paper describes the synthesis of various π-extended carbazole dimers via intramolecular oxidative cyclization using a chain precursor consisting of two carbazole units bridged by a nitrogen atom. A careful selection of the reaction conditions using 2,3-dichloro-5,6-dicyano--benzoquinone/sulfonic acid enabled the selective synthesis of a π-extended analogue with an angular (L-shape) structure in moderate yield. The preferential positions for the bonding of the two carbazole units in this π-extended derivative were determined by performing density functional theory calculations.

Synthesis, Structures, and Electronic Properties of 2,7-Anthrylene-Based Azacyclophanes Bearing -, -, and -Phenylenediamine Linkers.

A series of novel azacyclophanes consisting of 2,7-anthrylene and phenylene units were designed and synthesized by the Buchwald-Hartwig coupling reaction to investigate their unique electronic properties in multiple oxidized states. Cyclic voltammetry showed that the -phenylene derivative exhibited three reversible oxidation waves, whereas the - and -phenylene derivatives showed two quasi-reversible oxidation waves due to the complicated intramolecular interaction between the oxidized units and neutral units. Moreover, the absorption spectra of the -phenylene derivative in different oxidation states showed absorption bands at 865 and 1025 nm, which were attributed to intramolecular charge-transfer interactions.

Chemistry of Anthracene-Acetylene Oligomers XXVII. Iterative Synthesis, Structures, and Properties of Anthracene-Diacetylene Cyclic Oligomers with 10-Mesitylanthracene-1,8-diyl Units.

A series of cyclic oligomers consisting of 10-mesitylanthracene-1,8-diyl units and diacetylene linkers were synthesized as soluble π-conjugated compounds. Macrocyclic frameworks from dimer to octamer except heptamer were constructed from 1,8-diethynylanthracene derivatives by iterative coupling reactions. The rigid structure of the dimer, the strained structures of the trimer and the pentamer, and the belt-shaped structures of the other even-numbered oligomers were revealed by X-ray analysis and DFT calculations.

Donor-Donor'-Acceptor Triads Based on [3.3]Paracyclophane with a 1,4-Dithiafulvene Donor and a Cyanomethylene Acceptor: Synthesis, Structure, and Electrochemical and Photophysical Properties.

Donor-donor'-acceptor triads (1, 2), based on [3.3]paracyclophane ([3.3]PCP) as a bridge, with electron-donating properties (D') using 1,4-dithiafulvene (DTF; TTF half unit) as a donor and dicyanomethylene (DCM; TCNE half unit) or an ethoxycarbonyl-cyanomethylene (ECM) as an acceptor were designed and synthesized.

Synthesis and Electronic Properties of Length-Defined 9,10-Anthrylene-Butadiynylene Oligomers.

Linear π-conjugated oligomers consisting of anthracene and diacetylene units were readily synthesized by a one-pot process that involved desilylation and oxidative coupling from appropriate building units. We were able to isolate length-defined oligomers ranging from 2-mer to 6-mer as stable and soluble solids. The bathochromic shifts in the UV-vis spectra suggested that the π-conjugation was extended with elongation of the linear chain.

Oxidation State-Dependent Intramolecular Electronic Interaction of Carbazole-Based Azacyclophanes with 9,10-Anthrylene Units.

We designed an azacyclophane comprising 3,6-substituted carbazole and 9,10-anthrylene units to investigate the unique electronic properties of the oxidation states arising from the presence of multiple oxidizable azacyclophane. This compound and its analogue containing 1,4-phenylene in substitution of 9,10-anthrylene units were synthesized by Buchwald-Hartwig coupling reactions. Cyclic voltammograms of both the 9,10-anthrylene and 1,4-phenylene derivatives exhibited four quasi-reversible oxidation processes.

Isolable Triradical Trication of Hexaaza[1]paracyclophane with Embedded 9,10-Anthrylenes: A Frustrated Three-Spin System.

A new derivative of hexaaza[1]paracyclophane in which p-phenylenes are alternately replaced by 9,10-anthrylenes was prepared to investigate the impact on overall π-conjugation as well as conformational change of the macrocycle. The charge and spin distribution for one-electron and three-electron oxidation of the macrocycle was elucidated by means of electrochemical, spectroelectrochemical, EPR spectroscopic, and SQUID magnetometric methods. In particular, the triradical trication was successfully isolated as an air-stable salt, and moreover, its structure was disclosed by X-ray analysis.

Planar Anthracene-Acetylene Frameworks as a Stereogenic Motif.

Planar and rigid frameworks that consist of two 1,8-substituted anthracene units and two acetylene linkers were utilized as key structures for the generation of stereoisomers through the introduction of extra substituents. These compounds were synthesized from 1,8-substituted anthracene building units by a combination of coupling reactions. We designed diastereomers, enantiomers, and topomers by modifying the combination of the two linkers and the number of substituents at sterically crowded intraannular positions.

Synthesis of 1,2-Bis(2-aryl-1H-indol-3-yl)ethynes via 5-exo-Digonal Double Cyclization Reactions of 1,4-Bis(2-isocyanophenyl)buta-1,3-diyne with Aryl Grignard Reagents.

New π-conjugated 1,2-bis(2-aryl-1H-indol-3-yl)ethynes 1a-j having various substituents on the two aryl groups were efficiently synthesized via unusual 5-exo-digonal double isocyanide-acetylene cyclization reactions of 1,4-bis(2-isocyanophenyl)buta-1,3-diyne 3 and aryl Grignard reagents (R-MgBr, R = CH (1a), 4-HCCH (1b), 2-HCCH (1c), 3-MeOCH (1d), 3-(CH)NCH (1e), 4-FCCH (1f), 4-FCH (1g), 3-FCH (1h), 4-PhOCH (1i), and 2-Naph (1j)) in 19-85% yields. The UV-vis spectra were rationalized in detail using time-dependent DFT and single point calculations. The fluorescence emission peaks for 1a-j were observed at around 450 nm.

Intramolecular Charge-Transfer Interaction of Donor-Acceptor-Donor Arrays Based on Anthracene Bisimide.

We designed anthracene bisimide (ABI) derivatives having two triphenylamine (TPA) groups as donor units at the 9,10-positions to form a novel π-conjugated donor-acceptor system. These compounds and their analogues with ethynylene linkers were synthesized by Suzuki-Miyaura and Sonogashira coupling reactions, respectively. In UV-vis spectra, the linker-free derivatives showed broad absorption bands arising from intramolecular charge-transfer interactions.

Macrocyclic 2,7-Anthrylene Oligomers.

A macrocyclic compound consisting of six 2,7-anthrylene units was successfully synthesized by Ni-mediated coupling of the corresponding dibromo precursor as a novel π-conjugated compound. This compound was sufficiently stable and soluble in organic solvents due to the presence of mesityl groups. X-ray analysis showed that the molecule had a nonplanar and hexagonal wheel-shaped framework of approximately S6 symmetry.

Chemistry of anthracene-acetylene oligomers XXV: on-surface chirality of a self-assembled molecular network of a fan-blade-shaped anthracene-acetylene macrocycle with a long alkyl chain.

An anthracene cyclic dimer with two different linkers and a dodecyl group was synthesized by means of coupling reactions. The calculated structure had a planar macrocyclic π core and a linear alkyl chain. Scanning tunneling microscopy observations at the 1-phenyloctane/graphite interface revealed that the molecules formed a self-assembled monolayer that consisted of linear striped bright and dark bands.

Three-dimensional aromatic networks.

Three-dimensional (3D) networks consisting of aromatic units and linkers are reviewed from various aspects. To understand principles for the construction of such compounds, we generalize the roles of building units, the synthetic approaches, and the classification of networks. As fundamental compounds, cyclophanes with large aromatic units and aromatic macrocycles with linear acetylene linkers are highlighted in terms of transannular interactions between aromatic units, conformational preference, and resolution of chiral derivatives.

Chemistry of anthracene-acetylene oligomers XX: synthesis, structures, and self-association of anthracene-anthraquinone cyclic compounds with ethynylene linkers.

We have synthesized anthracene-acetylene oligomers, which contained one 10-substituted anthracene unit and one anthraquinone unit, by cyclization with Sonogashira coupling. X-ray analysis revealed an almost-planar framework and significant out-of-plane deformation around the inner carbonyl moiety because of steric hindrance. These compounds underwent self-association in solution and their association constants for monomer-dimer exchange were determined by variable-concentration (1)H NMR measurements in CDCl(3): 8 mol(-1) L (10-substituent: isopropyl), <5 mol(-1) L (methoxy), and 19 mol(-1) L (octyloxy).

Chemistry of anthracene-acetylene oligomers. XVII. Synthesis, structure, and dynamic behavior of 1,8-anthrylene pentamers and hexamers with acetylene linkers.

Three types of cyclic oligomers consisting of five or six 1,8-anthrylene units with acetylene linkers were synthesized by macrocyclization of the corresponding acyclic precursors with coupling reactions. DFT calculations at the M05/3-21G level revealed that the pentamers had a relatively rigid structure with strained alkyne carbons. Meanwhile, out of several possible conformers the hexamers preferred to take parallelogram-prism structures due to transannular π···π interactions, and conformational interconversions via rotation about the acetylene axes took place rapidly at room temperature.

Stereogenic motif consisting of rigid ring and intraannular chains: isolation and structures of stereoisomers of 9-alkyl-1,8-anthrylene-butadiynylene cyclic dimers.

Stereoisomers of the title pi-conjugated compounds with intraannular propyl and butyl groups were isolated by chromatography. The high barrier to isomerization is attributed to the steric hindrance between the alkyl chains and the rigid framework.

Synthesis, structure, and transannular pi-pi interaction of three- and four-layered [3.3]paracyclophanes.

The synthesis of three- and four-layered [3.3]paracyclophanes ([3.3]PCPs) 3-5 has been accomplished by utilizing the (p-ethylbenzenesulfonyl)methyl isocyanide (EbsMIC) method.

Molecular folding screen: folding and unfolding of 1,8-anthrylene-ethynylene oligomers by photochemical cycloaddition and thermal cycloreversion.

Molecular folding screens consisting of anthracene plates and acetylene linkers stereoselectively fold into a zigzag form by [4 + 4]photocycloaddition, and unfold by thermal cycloreversion.

New pi-conjugated system with a rigid framework of 1,8-anthrylene-ethynylene cyclic dimer and its monoanthraquinone analogue.

Two types of pi-conjugated compounds were synthesized by Sonogashira coupling, and their structures and properties were investigated by X-ray analysis and spectroscopic measurements. The monoanthraquinone compound features an out-of-plane deformation of the inner carbonyl moiety and dimer formation in crystals and solution.

Synthesis, structure, and transannular pi-pi interaction of multilayered [3.3]metacyclophanes.

The synthesis of a series of three- to six-layered [3.3]metacyclophanes ([3.3]MCPs) 3-6 has been successfully accomplished by the (p-tolylsulfonyl)methyl isocyanide (TosMIC) method as a critical coupling reaction.

[Investigation of radioactivity measurement of medical radioactive waste].

To explore the possibility of which medical radioactive wastes could be disposed as general wastes after keeping them a certain period of time and confirming that their radioactivity reach a background level (BGL), we made a survey of these wastes in several nuclear medicine facilities. The radioactive wastes were collected for one week, packed in a box according to its half-life, and measured its radioactivity by scintillation survey meter with time. Some wastes could reach a BGL within 10 times of half-life, but 19% of the short half-life group (group 1) including 99mTc and 123I, and 8% of the middle half-life group (group 2) including 67Ga, (111)In, and 201Tl did not reach a BGL within 20 times of half-life.

[A questionnaire about radiation safety management of the draining-water system at nuclear medicine facilities].

We conducted a questionnaire survey about radiation-safety management condition in Japanese nuclear medicine facilities to make materials of proposition for more reasonable management of medical radioactive waste. We distributed a questionnaire to institutions equipped with Nuclear Medicine facilities. Of 1,125 institutions, 642 institutes (52.