175885-77-5Relevant articles and documents
A Novel Sugar Sensing System Designed with a Cooperative Action of a Boronic-Acid-Appended Zinc Porphyrin and a 3-Pyridylboronic Acid Axial Ligand
Takeuchi, Masayuki,Kijima, Hideomi,Hamachi, Itaru,Shinkai, Seiji
, p. 699 - 705 (1997)
The cooperative action of two boronic acids is indispensable to the selective binding of saccharides in aqueous solution and the binding process can be spectrophotometrically monitored by using porphyrins as a chromophoric probe. It is not so easy, however, to synthesize porphyrins that satisfy these prerequisites, i.e., porphyrins bearing two appropriately-arranged boronic acid groups within a molecule. In this paper, we report that such a diboronic-acid-based porphyrin receptor can be easily designed by utilizing the self-assembling nature of a Zn(II) porphyrin and an axial ligand: That is, a mixture of boronic-acid-appended Zn(II) porphyrin (1-Zn) and 3-pyridylboronic acid (2) self-organizes to create a novel diboronic acid system for saccharide (S) recognition. Thus, the 1-Zn·2·S ternary complexes give the CD spectral pattern inherent to saccharide absolute configuration. The present study is a new example for sugar sensing using a boronic acid-porphyrin self-assembly system.
3-(Dimethylboryl)pyridine: Synthesis, structure, and remarkable steric effects in scrambling reactions
Wakabayashi, Shigeharu,Imamura, Saori,Sugihara, Yoshikazu,Shimizu, Makoto,Kitagawa, Toshikazu,Ohki, Yasuhiro,Tatsumi, Kazuyuki
, p. 81 - 87 (2008/09/16)
(Chemical Equation Presented) A facile method for the synthesis of 3-(dimethylboryl)pyridine (1a) is described. Compound 1a assembles into a rigid cyclic tetramer stabilized via intermolecular boron-nitrogen coordination bonds both in the crystalline state and in solution. The outstanding structural feature of 1a, as compared with previously reported 3-(diethylboryl)pyridine (2a) (which adopts a cone conformation), is that the tetramer of la adopts a 1,2-alternate conformation. To investigate the effect of substituents at the boron atom on the stabilities of the oligomers, scrambling experiments of the component molecules using 1, 2, and 3-(di-n-butylboryl)pyridines 3 were carried out. Although heating at 80-90°C for 20 h was required to attain the equilibrium of the scrambling reactions when the component molecules of the tetramers were 2 or 3, the scrambling in 1 proceeded under relatively mild conditions (60°C, 3 h). This difference in reaction conditions required for 1, as compared to conditions required for 2 or 3, could not be explained solely by the stabilities based on bond lengths or THC.1g It appears that whereas only an SN1-type pathway may be involved in the scrambling of 2 or 3, both SN1- and SN2-type mechanisms operate simultaneously during scrambling reactions of 1 or an intermediate mechanism between SN1 and SN2 operates, which was supported by kinetic studies and calculations using model compounds.
