Synthesis of N-functionalized oleamide derivatives

Oleamide is an interesting compound, which shows various pharmacological activities including the inhibitory effect of gap junction formation. Recently, the studies of the gap junction have been some of the hot topics in biology and its inhibitors have become more useful tools [Cravatt, B. F.; Garcia, O. P.; Siuzdak, G.; Gilula, N. B.; Henriksen, S. J.; Boger, D. L.; Lerner, R. A. Science1995, 268, 1506-1509; Cravatt, B. F.; Lerner, R. A.; Boger, D. L. J. Am. Chem. Soc.1996, 118, 580-590; Guan, X; Cravatt, B. F.; Ehring, G. R.; Hall, J. E.; Boger, D. L.; Lerner, R. A.; Gilula, N. B. J. Cell Biol.1997, 139, 1785-1792; Boger, D. L.; Patterson, J. E.; Guan, X.; Cravatt, B. F.; Lerner, R. A.; Gilula, N. B. Proc. Natl. Acad. Sci. U.S.A.1998, 95, 4810-4815; Ito, A.; Morita, N.; Miura, D.; Koma, Y.; Kataoka, T. R.; Yamasaki, H.; Kitamura, Y.; Kita, Y.; Nojima, H. Carcinogenesis2004, 25, 2015-2022]. However, many reports suggest that the functionalizations of oleamide to retain its biological activity were difficult [Boger, D. L.; Patterson, J. E.; Guan, X.; Cravatt, B. F.; Lerner, R. A.; Gilula, N. B. Proc. Natl. Acad. Sci. U.S.A.1998, 95, 4810-4815; Ito, A.; Morita, N.; Miura, D.; Koma, Y.; Kataoka, T. R.; Yamasaki, H.; Kitamura, Y.; Kita, Y.; Nojima, H. Carcinogenesis2004, 25, 2015-2022]. The synthesis of the functionalized oleamide derivatives, whose biological activity is not blocked, has become attractive in both the biological and chemical fields.Herein, by linking the fluorophore to the oleamide by alkyl chains, we synthesized the fluorescently tagged oleamide whose biological feature is similar to that of oleamide. Moreover, we also synthesized other bioactive derivatives tagged by other groups such as the sugars and biotin via alkyl chain linkers.     

A flexible coordination polymer crystal providing reversible structural and magnetic conversions

Structural flexibility is a remarkable characteristic of coordination polymers and significant for the attainment of environmental responsivity. We have prepared a 2D cyanide-bridged MnIICrIII coordination polymer, [Mn(NNdmenH)(H2O)][Cr(CN)6].H2O (1; NNdmen = N,N-dimethylethylenediamine), with sophisticatedly arranged removable water coligands. The compound clearly showed a reversible single-crystal-to-single-crystal transformation between the 2D sheet and a 3D pillared-sheet framework of dehydrated [Mn(NNdmenH)][Cr(CN)6] (1a). The structural change was reversible and accompanied with generation/cleavage of CN-Mn bonds between 2D sheets by dehydration/hydration. Compounds 1 and 1a also exhibited a ferrimagnetic ordering at 35.2 and 60.4 K, respectively, and the magnetic characteristics were reversibly converted by guest adsorption/desorption. In addition, the dehydrated 1a demonstrated a size-selective solvent adsorption linking chemi- and physisorption processes and shrinkage/expansion of its framework. The flexible magnetic framework incorporating removable coligands delivered multifunctions with chemical response.     

Anthracene array-type porous coordination polymer with host-guest charge transfer interactions in excited states

Confinement of electron donor guests affords an efficient, photo-induced charge transfer (CT) with the anthracene moieties of a porous coordination polymer.     

Simultaneous detection of N-terminal fragment ions in a protein mixture using a ruthenium(II) complex

Use of a bis(terpyridine)ruthenium(II) derivative as an N-terminal labeling reagent resulted in the simultaneous detection and individual determination of all the N-terminal fragments of the proteins in a mixture without requiring any separation. All of the N-termini of the guanidinated proteins were labeled selectively by the ruthenium complex (-CO-labeling). After chymotryptic digestion, the fragments were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and post-source decay (PSD). The -CO moiety exclusively enhanced N-terminal fragment ions in mass spectra and enabled easy N-terminal sequencing. In a mixture containing three different proteins (lysozyme, ubiquitin, and insulin), all of the N-terminal fragment ions labeled with the ruthenium complex were found to produce uniformly intense peaks without the detection of the other unlabeled fragments. The N-terminal sequences of these ions were determined individually by PSD analysis. Application to unknown proteins from Thermus thermophilus HB8 with two-dimensional electrophoretic separation resulted in the successful determination of the N-terminal sequence and easy identification of the target protein.     

Series of trinuclear NiIILnIIINiII complexes derived from 2,6-Di(acetoacetyl)pyridine: synthesis, structure, and magnetism

Eighteen trinuclear NiII2LnIII complexes of 2,6-di(acetoacetyl)pyridine (H2L) (Ln=La-Lu except for Pm) were prepared by a "one-pot reaction" of H2L, Ni(NO3)2.6H2O, and Ln(NO3)3.nH2O in methanol. X-ray crystallographic studies indicate that two L2- ligands sandwich two NiII ions with the terminal 1,3-diketonate sites and one LnIII ion with the central 2,6-diacylpyridine site, forming the trinuclear [Ni2Ln(L)2] core of a linear NiLnNi structure. The terminal Ni assumes a six-coordinate geometry together with methanol or water molecules, and the central Ln assumes a 10-coordinate geometry together with two or three nitrate ions. The [Ni2Ln(L)2] core is essentially coplanar for large Ln ions (La, Ce, Pr, Nd) but shows a distortion with respect to the two L2- ligands for smaller Ln ions. Magnetic studies for the Ni2Ln complexes of diamagnetic LaIII and LuIII indicate an antiferromagnetic interaction between the terminal NiII ions. A magnetic analysis of the Ni2Gd complex based on the isotropic Heisenberg model indicates a ferromagnetic interaction between the adjacent NiII and GdIII ions and an antiferromagnetic interaction between the terminal NiII ions. The magnetic properties of other Ni2Ln complexes were studied on the basis of a numerical approach with the Ni2La complex and analogous Zn2Ln complexes, and they indicated that the NiII-LnIII interaction is weakly antiferromagnetic for Ln=Ce, Pr, and Nd and ferromagnetic for Ln=Gd, Tb, Dy, Ho, and Er.     

Synthesis of conjugated polymers with azobenzene moieties in the main chain

Poly(phenylenevinylene)‐based conjugated polymers with azobenzene groups in the main chains were prepared by the Pd‐catalyzed coupling polymerization of divinylarenes with dihaloarenes. The Pd‐catalyzed coupling polymerization of 4,4′‐divinylazobenzene with dihaloarenes such as 1,3‐dibromobenzene, 1,4‐dibromo‐2,5‐dihexylbenzene, 4,4′‐dibromoazobenzene, and 4,4′‐diiodoazobenzene resulted in polymers with poor solubility. In contrast, soluble polymers containing azobenzene moieties in the main chains were attainable from divinylbenzenes with 4,4′‐dihaloazobenzenes if either or both of the monomers possessed hexyl groups on the aromatic rings. The number‐average molecular weight of the polymer exceeded 10,000 under optimized conditions, and the polymer showed a remarkably redshifted absorption in the visible region (456 nm). ¹H NMR and IR spectra supported that the polymers having only trans‐geometry for the double bonds. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1057–1063, 2000     

Transformation of the cationic growing center of poly(tetrahydrofuran) into an anionic one by bis(pentamethylcyclopentadienyl)samarium

Transformation of the cationic growing center of living poly(tetrahydrofuran) [poly(THF)] into an anionic one was achieved in high efficiency (62%) by the end-capping of living poly(THF) with potassium iodide followed by the reduction with bis(pentamethylcyclopentadienyl)samarium (Cp*₂Sm), whereas the direct reduction with Cp*₂Sm without the end-capping resulted in the formation of poly(THF) with pentamethylcyclopentadienyl group at the terminal. The increase in the molecular weight of poly(THF) after the reduction was observed, which indicates the presence of the dimerization of poly(THF) during the reduction. The polymerization of a variety of electrophilic monomers including δ-valerolactone, 2-oxo-1,3-dioxane, and alkyl methacrylates with the macroanion provided good yields of the corresponding block copolymers consisting of both cationically and anionically polymerizable monomers. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2209–2214, 1998