ABSTRACT
The development of an expedient synthesis toward quinoxaline ring-embedded polyacenoquinone esters with the generic structure A is demonstrated by the synthesis of penta- and hexacenoquinone esters. They are potential n-type small molecules, capable of undergoing successive reductions and self-assembling in face-to-face π-stacks.
Subject(s)
Esters/chemistry , Esters/chemical synthesis , Quinones/chemistry , Quinones/chemical synthesis , Quinoxalines/chemistry , Crystallography, X-Ray , Electrons , Models, Molecular , Molecular Structure , StereoisomerismABSTRACT
New rigid bicyclic N-anthrylsuccinimide 1a, 1b, 2a, and 2b were prepared. The C(aryl)-N(imide) bond rotational barriers, intra/intermolecular arene-arene interactions, and photophysical properties were investigated. The rotational behaviors are more significantly controlled by the position of C(aryl)-N(imide) connection than the sidewall framework. The fluorescence energy transfer (Φ(ET)) in 1a and 1b was estimated to be 61% and 53%, respectively. The difference is attributed to the position of C(aryl)-N(imide) connection, which directly influences the relative orientation of donor (naphthalene) and acceptor (anthracene).
ABSTRACT
[structure, reaction: see text] The U-shaped, multifunctionalized tetraetheno-bridged dicyclopenta[b,i]anthracenediol 10 was synthesized to serve as a platform molecule. The molecule was prepared from the Diels-Alder adduct 5a of tricycloundecatriene 3 and bicyclo[2.2.2]octene-fused p-benzoquinone 4. Functionalization of 10 to construct crab-like molecules was achieved via the base-promoted bis-O-alkylation of two endo-oriented hydroxyl groups at termini in 10 with the following alkyl halides: allyl, propagyl, and benzyl bromides; 1-bromo- and 1-iodo-4-(bromomethyl)benzene; 9-(bromomethyl)anthracene; 1-(bromomethyl)pyrene; and isomeric bromomethylpyridines. Single-crystal X-ray structures were obtained for bis-phenyl (21) and bis-pyrenyl (25) crabs, and for the silver(I) complex (32 and 33) crabs. The silver(I) complex 32 from bis-o-pyridyl crab 30 is a [2+2] dimeric dimetallocyclophane, and 33 from bis-m-pyridyl crab 29 is a [1+1] metallo-bridged cyclophane. The self-assembled intramolecular pi-stacking of pyrenyl rings in 25 with an interplanar distance of 3.40 A and the consequent pi-pi interactions were revealed by the X-ray crystal structure and its luminescence property.
Subject(s)
Bridged Bicyclo Compounds, Heterocyclic , Octanes , Anthracenes/chemical synthesis , Anthracenes/chemistry , Bridged Bicyclo Compounds/chemical synthesis , Bridged Bicyclo Compounds/chemistry , Bridged Bicyclo Compounds, Heterocyclic/chemical synthesis , Bridged Bicyclo Compounds, Heterocyclic/chemistry , Crystallography, X-Ray , Hydrogen Bonding , Luminescence , Models, Molecular , Molecular Conformation , Octanes/chemical synthesis , Octanes/chemistry , StereoisomerismABSTRACT
[reaction: see text] 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-alpha-diketones with benzene-1,2-diamines. The unsymmetric bis-quinoxalines, with electronically different substituents, and the quinoxaline ring-attached alpha-diketones were also prepared. Their luminescence properties were examined and described.
ABSTRACT
The tetracyclic ring-fused, facially dissymmetric maleic anhydride 2 was synthesized from compound 9 obtained from the Diels-Alder cycloaddition of the bicyclic ring-fused cyclohexadiene 1 and acetylenedicarboxylate. Maleic anhydride 2 readily underwent the Diels-Alder cycloadditions with anthracene, 1,3-diphenylisobenzofuran, cyclopentadiene, 1,3-cyclohexadiene, 6,6-dimethylfulvene, and o-quinodimethane. All the cycloadditions occurred exclusively on the pi-face syn to the etheno bridge of 2, thereby in cases of the cycloadditions with anthracene, cyclopentadiene, 1,3-cyclohexadiene, and 6,6-dimethylfulvene producing the corresponding adducts 11a, 18b, 22b, and 23b that contain three double bonds aligned in parallel. The structures of 18b and 22b were unequivocally established by the X-ray structural determinations. The molecular structure of maleic anhydride 2 was analyzed by X-ray crystallography to have a pyramidalized dienophilic double bond, which appeared to correlate well with the observed pi-facial selectivity.
