An All-Photonic Molecule-Based D Flip-Flop

The photochromic fluorescence switching of a fulgimide derivative was used to implement the first molecule-based D (delay) flip-flop device, which works based on the principles of sequential logic. The device operates exclusively with photonic signals and can be conveniently switched in repeated cycles. \ua9 2011 American Chemical Society

Hepatitis C Virus Antigenic Convergence

Vaccine development against hepatitis C virus (HCV) is hindered by poor understanding of factors defining cross-immunoreactivity among heterogeneous epitopes. Using synthetic peptides and mouse immunization as a model, we conducted a quantitative analysis of cross-immunoreactivity among variants of the HCV hypervariable region 1 (HVR1). Analysis of 26,883 immunological reactions among pairs of peptides showed that the distribution of cross-immunoreactivity among HVR1 variants was skewed, with antibodies against a few variants reacting with all tested peptides. The HVR1 cross-immunoreactivity was accurately modeled based on amino acid sequence alone. The tested peptides were mapped in the HVR1 sequence space, which was visualized as a network of 11,319 sequences. The HVR1 variants with a greater network centrality showed a broader cross-immunoreactivity. The entire sequence space is explored by each HCV genotype and subtype. These findings indicate that HVR1 antigenic diversity is extensively convergent and effectively limited, suggesting significant implications for vaccine development

Designing Dendrimers

The term dendrimer derives from the Greek words dendron (tree) and meros (part) and refers to its regularly and highly branched structure. Like trees, dendrimers usually exhibit aesthetically pleasant structures, but the interest in a specific dendrimer does not depend, of course, only on its beauty; rather, it depends on the "fruit" (i.e., the specific function) that the dendrimer is able to produce

Dinuclear Tris(1-pyrazolyl)methane Complexes of Ru(II)

By exploiting the "complexes-as-metals/complexes-as-ligands" synthetic strategy, six new dinuclear achiral complexes of Ru(II), containing the tripodal ligand tris(1-pyrazolyl) methane (tpm), a chelating ligand (L-L) such as 2,2'-bipyridine (2,2'-bpy), 1,10-phenanthroline (phen) or 2,2'-biquinoline (biq), and either pyrazine (pz) or 4,4'-bipyridine (4,4'-bpy) as bridging ligands (BL), have been prepared and fully characterized. The starting building blocks, many of which have been synthesized for the first time, have been conveniently prepared by improved literature methods. The reactivity of these building blocks in specific experimental conditions has been rationalized. All novel compounds have been characterized fully by elemental analysis and FT-IR. (1)H NMR spectra have been carefully assigned and interpreted on the basis of possible inductive and magnetic anisotropic effects exerted by the ligands. Electrochemical, UV/Vis spectroscopic, and luminescence studies have been carried out on all the dinuclear complexes and their precursor species; the collected data have been discussed and thoroughly interpreted. Ru(II)/Ru(III) mixed-valence species of two dinuclear compounds have been investigated by spectroelectrochemistry and assigned to the Robin and Day's Class II group on the basis of the experimental parameters obtained