Rigid U-shaped molecules containing syn-facially situated quinoxaline rings have been synthesized in three steps, by a combination of the Diels−Alder reaction, the ruthenium-catalyzed oxidation, and ...the Zn(OAc)2-catalyzed condensation of the resulting bis-α-diketones with benzene-1,2-diamines. The unsymmetric bis-quinoxalines, with electronically different substituents, and the quinoxaline ring-attached α-diketones were also prepared. Their luminescence properties were examined and described.
Based on the methodology of repetitive Diels–Alder reactions, the rack- and U-shaped polycyclic compounds
15b
,
17b
,
19
,
20
, and
21
were constructed utilizing ...1,2,3,4-tetrachloro-5,5-dimethoxycyclopentadiene (TDCp),
p-benzoquinone, and norbornadiene as starting materials. These spacer molecules are composed of nine linearly
syn-fused polyhydrobenzene rings (i.e., polyhydrononacene), in which all the etheno-bridge double bonds are arranged on the same side of the carbon skeletons. Upon irradiation with an ordinary tungsten lamp,
17b
and
21
underwent 2+2photocyclization to form quadruple- and double-caged compounds
18
and
22
, respectively. The structure of
20
was analyzed by X-ray crystallography and found to have U-shaped framework.
Graphic
Derivatives of 2,3-(1,4-dialkoxyaceno)norbornadiene 1 − 4 underwent ring-opening metathesis polymerization (ROMP) reactions with a ruthenium carbene complex Cl2(PCy3)2RuCHPh to afford the ...corresponding polymers P1 − P4 with narrow polydispersity. These materials exhibited luminescence both in solution and as films, whereas P3 and P4 were used successfully for the fabrication of light emitting diodes (LED). The device ITO/P4/Ca/Al, made of a spin-coated layer of P3 or P4, displayed white light that can be turned on at 7 V with a maximum intensity of 427 cd/m2 at 15 V. The white electroluminescence is composed of a blue emission band from the aromatic chromophore and a red component derived from solid aggregates. The performance of devices can be improved by insertion of an additional electron-transporting layer, i.e., 1,3,5-tris(2‘-(1‘-phenyl-1‘-H-benzimidazole)benzene (TPBI). The device ITO/P4/TPBI/Mg:Ag displayed blue light with a turn-on voltage of 5 V and maximal intensity of 930 cd/m2 at 15 V. The change of chromaticity can be ascribed to a shift of charge recombination sites in the bulk of P4 film. The phenomenon was verified by adjusting the thickness of TPBI layer, whereas a continuous variation in color was observed upon changing bias.
The easily accessible and multi-functionalized 5,8-dimethoxy-6,7-dihydroxy methyl-1,4-dihydro-1,4-methanonaphthalene (
1
) has been utilized as the basic building material to synthesize the symmetric ...bis-methanonaphthalene-fused crown ethers
14a–
d
(BMN-16-crown-4, BMN-22-crown-6, BMN-28-crown-8, and BMN-34-crown-10), that are constructed based on the connection between the α,β-bis-benzylic carbon atoms of diol
1
and oligoethylene glycols (
9a–
d
) via two synthetic routes keyed upon the method of Williamson ether synthesis.
Graphic
The synthesis of
syn-sesterbicyclo2.2.2octene (
7
) bilaterally grafted by an exocyclic
s-
cis-butadiene moiety is achieved from 1,8,9,10-tetrachloro-11,11-dimethoxy-
endo-tricyclo6.2.1.0
...2,7undeca-3,5,9-triene (
8
) employing repetitive Diels–Alder cycloadditions between 1,3-cyclohexadiene, generated from
p-benzoquinone, and diethyl fumarate or maleic anhydride as the exocyclic butadienyl equivalent, followed by subsequent transformation to the conjugated diene moieties. In comparison with the corresponding sesquibicyclo2.2.2octene
6
, the
1H NMR demonstrates the anisotropic shielding effect operating within the three parallel laticyclic double bonds. However, the UV absorption of
7
shows less effect by the increase of laticyclic conjugated ethylene units.
Graphic
(S)-((2-Methylbutyl)thio)hydroquinone was prepared from benzoquinone and (S)-2-methylbutyl mercaptan. One series of cholesteric copolycarbonates was prepared from this chiral hydroquinone, ...methylhydroquinone, and 4,4‘-dihydroxybiphenyl by interfacial polycondensation with diphosgene. All copolycarbonates were noncrystalline and decomposed upon heating above 250 °C. A Grandjean texture was only observed for one sample. A second series of cholesteric copolycarbonates was prepared from isosorbide, methylhydroquinone, and 4,4‘-dihydroxybiphenyl. Four different polycondensation methods were studied and compared in this case. The best results were obtained by polycondensation in pyridine containing organic cosolvents. Two copolycarbonates of isosorbide were obtained which formed a broad cholesteric phase with a Grandjean texture.
The title compound
6 was synthesized in nine steps, starting from the Diels-Alder adduct
21 of ketomethanoethanonaphthalene
20 and
p-benzoquinone, via 7,8-dimethylidene-diethenoanthracene
10 followed ...by Diels-Alder reaction with (
E)-bis(phenylsulfonyl)ethylene and aromatization. Photocyclization of
6 led to
32 via an intramolecular 2+2 cycloaddition. Hydrogenation and epoxidation of
6 gave the corresponding bis-benzo hydrocarbon
33 and bis-epoxide
34. Bromination of
6 proceeded by transannular reaction to produce
N-type
exo, endo dibromide
35b and
U-type
exo, exo dibromide
36b. Compound
6 underwent thermal decomposition at 210 ± 5°C to form naphthalene and benzobarrelene.
The title compound 6 was synthesized starting from
20 via intermediate
10 by sequential Diels-Alder reactions.
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