- Activation of Aptamers with Gain of Function by Small-Molecule-Clipping of Intramolecular Motifs
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Click reactions have the advantages of high reactivity, excellent orthogonality, and synthetic accessibility. Inspired by click reactions, we propose the concept of “clipped aptamers”, whose binding affinity is regulated by the “clip”-like specific intera
- Huang, Mengjiao,Li, Tingyu,Xu, Yuanfeng,Wei, Xinyu,Song, Jia,Lin, Bingqian,Zhu, Zhi,Song, Yanling,Yang, Chaoyong
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p. 6021 - 6028
(2021/01/29)
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- Syntheses, Spectroscopic Properties, and Computational Study of (E, Z)-Ethenyl and Ethynyl-Linked BODIPYs
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A series of (E,Z)-ethenyl- and ethynyl-linked boron dipyrromethene (BODIPY) dimers were synthesized in 23-34% yields by condensation of pyrroles with the corresponding bis-benzaldehydes, followed by oxidation and boron complexation. The BODIPY dimers were characterized by 1H, 13C, and 11B NMR spectroscopy, high-resolution mass spectrometry, and, in the cases of 1b, 2, and 3, by X-ray crystallography. The spectroscopic properties for this series of dimers were investigated in tetrahydrofuran solutions, and very similar absorption and emission profiles were observed for all dimers. Density functional theory calculations show minimal conjugation between the two BODIPY units in the dimers, as a result of the large dihedral angle between the BODIPYs and the linker. The (E)-ethenyl-linked dimer 1a showed the highest fluorescence quantum yield of all dimers investigated in this study.
- Zhang, Guanyu,Zhao, Ning,Bobadova-Parvanova, Petia,Wang, Maodie,Fronczek, Frank R.,Smith, Kevin M.,Vicente, M. Gra?a H.
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p. 6256 - 6265
(2018/07/15)
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- Alternating oligo(o,p-phenylenes) via ruthenium catalyzed diol-diene benzannulation: orthogonality to cross-coupling enables de novo nanographene and PAH construction
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Ruthenium(0) catalyzed diol-diene benzannulation is applied to the conversion of oligo(p-phenylene vinylenes) 2a-c, 5 and 6 to alternating oligo(o,p-phenylenes) 10a-c, 11-13. Orthogonality with respect to conventional palladium catalyzed biaryl cross-coup
- Kasun, Zachary A.,Sato, Hiroki,Nie, Jing,Mori, Yasuyuki,Bender, Jon A.,Roberts, Sean T.,Krische, Michael J.
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p. 7866 - 7873
(2018/10/31)
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- Precipiton reagents: Precipiton phosphines for solution-phase reductions
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(Equation Presented) Several Precipiton phosphines were prepared and employed in the Staudinger reaction and in the reduction of secondary ozonides. Both amines and aldehdyes were obtained in good to excellent yields and purities. After use of the phosphine, isomerization and precipitation of the spent phosphorus reagent were induced by exposure to visible light in the presence of erythrosin B, a triplet sensitizer. Products were isolated by simple filtration. The use of the triplet sensitizer has the added advantage of eliminating [2 + 2] cycloaddition reactions between trans-Precipitons.
- Bosanac, Todd,Wilcox, Craig S.
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p. 2321 - 2324
(2007/10/03)
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- Synthesis and Intramolecular Electron- and Energy-Transfer Reactions of Polyyne- or Polyene-Bridged Diporphyrins
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A series of geometrically restricted polyyne- or polyene-bridged diporphyrins 1-7 has been prepared by a convenient, one-pot, double porphyrin cyclization reaction in acceptable yields from the corresponding dialdehydes 1-7CHO.Polyene-bridged diporphyrins 8 and 9 were prepared by a double Horner-Emmons-Wadsworth reaction of formyl-substituted zinc-porphyrin monomer 12 with bis-phosphonate esters 13 and 14, respectively.The diporphyrins 1-9 were transformed into zinc-free-base and zinc-ferric hybrid diporphyrins.Photoinduced intramolecular electron transfer in the zinc-ferric hybrid diporphyrins as well as intramolecular excitation energy transfer in the zinc-free-base hybrid diporphyrins have been studied by picosecond time-resolved fluorescence spectroscopy.Rate constants through the polyene-bridges are larger than those through the polyyne-bridges in both reactions.The distance dependence of the electron-transfer rate was found to be quite small: the attenuation factors were determined to be 0.08 and 0.1 Angstroem-1 for the polyene- and polyyne-bridged diporphyrins, respectively.The distance dependence of the energy-transfer rate was quite similar to that of the electron transfer and was explained better by the Dexter mechanism rather than by the Foerster mechanism.These results clearly demonstarate that the linear ?-conjugated polyyne and polyene spacers enhance through-bond electronic coupling between the donor and acceptor.
- Osuka, Atsuhiro,Tanabe, Nobuhiro,Kawabata, Shigeki,Yamazaki, Iwao,Nishimura, Yoshinobu
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p. 7177 - 7185
(2007/10/03)
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- A HIGHLY EFFICIENT VERSION OF THE PALLADIUM-CATALYSED ARYLATION OF ALKENES WITH ARYL BROMIDES
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The palladium-catalysed arylation of alkenes with aryl bromides or iodides is shown to proceed in high yields at very low palladium concentration when carried out in a suitable strongly polar solvent with a carboxylate anion as base.The preferred combination is N,N-dimethylformamide with sodium acetate.The reaction is markedly dependent on the substituents in the aryl bromide, being favoured by electron-withdrawing groups.Turnover numbers up to 134,000 have been achieved.
- Spencer, Alwyn
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p. 101 - 108
(2007/10/02)
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