Craig L. Hill

Synthesis and characterization of several binuclear and mononuclear bis(α-dioximato)nickel(II) complexes

Abstract Four binuclear bis(α-dioximato)nickel(II) complexes (where the dioxime is 4,5-octanedione dioxime) were prepared by treatment of a monomeric bis(α-dioximato)nickel(II) species with the linking reagents (F 2 BRBF 2 , R = 1,4 -C 6 H 4 or -(CH 2 ) 4 −. The binuclear complexes consist of one FBRBF moiety linking the two bis(α-dioximato)nickel(II) units together by attachment of each boron to two oxygen atoms of each of the two bis(α-dioximato)nickel(II) units. Several mononuclear bis(α-dioximato)nickel(II) complexes (where the dioxime is either 3,4-hexanedione dioxime or 4,5-octanedione dioxime) containing two RBF units (R = C 6 H 5 , n-C 4 H 9 ), one RBF unit (R = C 6 H 5 ) and one BF 2 unit, or two BF 2 units bridging two oxygens of the dioximes were also prepared. The complexes containing two RBF units exist in two isomeric forms that can be separated using adsorption chromatography. The mononuclear and binuclear complexes were characterized by their NMR ( 1 H, 13 C, and 19 F) and IR spectra. The complexes containing RBF units were stable in neutral and basic media but unstable in acidic media. The compounds with RBF units were also unstable in the presence of Lewis acids. Reaction of the complexes containing RBF units with BF 3 gave the complexes containing two BF 2 units in quantitative yields. Exchange of the α-dioximato ligands between bis(α-dioximato)nickel(II) complexes containing either two hydrogens or two boron moieties bridging the oxime oxygens was unobserved in dichloromethane over a period of at least one month at room temperature. Ligand exchange was observed in acidified dichloromethane for the complexes containing hydrogen bridges but not observed in this medium for the complexes containing BF 2 bridges.

CD81 receptor expression in human cells

Publisher Summary This chapter determines the level of expression in continuous cell culture systems and primary human cells to develop therapeutic modalities that prevent the binding of hepatitis C virus (HCV) to the CD81 receptor. The chapter also determines nine cell systems with the highest CD81 expression, using flow cytometric analysis. In the study discussed in the chapter, 23 polyoxometalates, a bicyclam, and three sulfated alkyl oligosaccharides were evaluated for their ability to inhibit CD81 binding, using the best cell system (CEM cells). Cells were washed with phosphate-buffered saline (PBS) and then incubated for one hour with an isotype control or CD81-PE. It could also be fixed with 1% paraformaldehyde and then analyzed on a FACScalibur cell sorter. The cells were incubated with the compounds, washed, and processed. The lack of CD81 receptors on human HepG2 cells explains the inability to infect these cells with HCV. The results indicate that the capacity to mediate or inhibit HCV attachment by CD81 should be studied in primary human lymphocytes. The HCV envelope protein E2 binds to human CD81, a tetraspanin expressed on hepatocytes and lymphocytes. Inhibitors of this binding could also prevent HCV transmission.