ABSTRACT
Molecular design strategy to control the crystal structure of two-dimensional (2D) π-extended organic semiconductors has not been intensively explored. We synthesized an unsymmetric tetrabenzoporphyrin derivative (TIPS-Ph-BP) to demonstrate the effect of molecular symmetry on crystal packing. TIPS-Ph-BP formed an antiparallel slipped π-stacking and 2D herringbone-like structure. An unsymmetric structure would make 2D π-stacking more stable than a one-dimensional (1D) columnar structure to counteract steric and electronic imbalance in the crystal. As a result, TIPS-Ph-BP achieved the high hole mobility of 0.71 cm2 V-1 s-1.
ABSTRACT
Quinolines are an important class of compounds, and the development of new efficient synthetic strategies for the construction of quinolines is of considerable interest. Zinc triflate catalyzed cyclization of ethenetricarboxylate derivatives with 2-aminobenzaldehydes has been examined. The reaction of ethenetricarboxylate with 2-aminobenzaldehydes in the presence of zinc triflate (0.2 equiv) at 80 degrees C in ClCH(2)CH(2)Cl gave bridged tetrahydroquinoline derivatives in 15-95% yield. On the other hand, the reaction at room temperature in CH(2)Cl(2) gave hydroxy tetrahydroquinoline derivatives in 38-90% yield. Heating the hydroxy tetrahydroquinolines with zinc triflate (0.2 equiv) at 80 degrees C in ClCH(2)CH(2)Cl led to the bridged tetrahydroquinoline derivatives in 75-96% yield. Thermal reaction of the bridged tetrahydroquinolines (180 degrees C) gave indole derivatives regioselectively.
Subject(s)
Benzaldehydes/chemistry , Hydrocarbons, Chlorinated/chemistry , Mesylates/chemistry , Quinolines/chemical synthesis , Tricarboxylic Acids/chemistry , Catalysis , Crystallography, X-Ray , Molecular Structure , Quinolines/chemistry , StereoisomerismABSTRACT
We have developed 2'-O-methyl-RNAs having phosphorylated cyclohexane at the 5' and/or 3'-terminal adenine. These 2'-O-methyl-RNAs formed less stable duplex with the longer target RNA than that with the short target RNA. We tried to improve the short-RNA selective hybridization property by the synthesis of 2'-O-methyl-RNAs having terminal guanine modifications.
Subject(s)
RNA, Untranslated/chemistry , Cyclohexanes/chemistry , Nucleic Acid Denaturation , Nucleic Acid Hybridization , Oligonucleotides/chemical synthesis , Oligonucleotides/chemistry , PhosphorylationABSTRACT
We study the Arnold tongue of a nonlinear electrochemical oscillator entrained to an electrical periodic forcing. In our system, the width of the 1:3 entrainment region was broader than that of the 1:2 region. The 1:1 and 1:3 regions became monotonically broad when the conductance of the electrode cell was increased by the electrochemical redox reaction of Fe(CN)(6)(4-) <==> Fe(CN)(6)(3-) + e. In contrast, the 1:2 region changed nonmonotonically. In particular, the rate of change in the 1:2 region was greater than those of the 1:1 and 1:3 regions. These experimental results were qualitatively reproduced by the use of phase response curves of a corresponding mathematical model. We also discuss higher harmonics included in a limit cycle describing the isolated oscillator, dependence on the redox reaction, and hysteresis due to a bistability.
ABSTRACT
Zinc Lewis acid-catalyzed cyclization of ethenetricarboxylate derivatives 1 with 2-ethynylanilines has been examined. Reaction of 1,1-diethyl 2-tert-butyl ethenetricarboxylate 1b with 2-(trimethylsilylethynyl)aniline substrates in the presence of Zn(OTf)(2) gave bridged quinoline derivatives in 43-85% yield. The reaction of 1b with 2'-aminoacetophenone also gave the bridged quinoline derivative in 41% yield. Thermal reaction of bridged quinolines (180-190 degrees C) afforded indole derivatives in moderate to good yields.
Subject(s)
Aniline Compounds/chemistry , Heterocyclic Compounds, Bridged-Ring/chemical synthesis , Quinolines/chemical synthesis , Tricarboxylic Acids/chemistry , Zinc/chemistry , Catalysis , Heterocyclic Compounds, Bridged-Ring/chemistry , Indoles/chemical synthesis , Indoles/chemistry , Molecular Structure , Quinolines/chemistryABSTRACT
We have developed new artificial oligonucleotide probes that show selective recognition for short RNA targets over long RNA targets. Our results suggested that modification of the termini of the oligonucleotide probes by bulky substituents such as cyclohexyl and 4-(3,6,9-trioxaundecylenedioxy)phenyl (Bzcr) groups significantly improved the selectivity of the probes toward the short RNA targets. The selectivity was further improved by the addition of a phosphate group on the cyclohexane ring. Although much improved selectivity toward short RNA targets is desirable in a general sense, it is particularly applicable to the selective detection of matured-miRNA over pre-miRNAs.
Subject(s)
Cytidine/analogs & derivatives , Deoxyadenosines/chemical synthesis , Oligonucleotides/chemical synthesis , Oligonucleotides/metabolism , Organophosphorus Compounds/chemical synthesis , RNA/metabolism , Cytidine/chemical synthesis , Cytidine/chemistry , Deoxyadenosines/chemistry , MicroRNAs/metabolism , Models, Molecular , Nucleic Acid Conformation , Nucleic Acid Hybridization , Oligonucleotides/chemistry , Organophosphorus Compounds/chemistry , Structure-Activity Relationship , ThermodynamicsABSTRACT
2'-O-methyl RNAs having phosphorylated cyclohexane groups at the 5' and 3'-terminal bases were synthesized and their hybridization properties toward RNA targets were studied. It was proved that the duplex of the modified 2'-O-methyl RNAs and the target RNA longer than the 2'-O-methyl RNA was less stable than that with the short target. In addition, it was also clarified that the selectivity toward the short target was improved by the introduction of the phosphate group in comparison with that without the phosphate group.
