Insights in the rational design of synthetic multivalent glycoconjugates as lectin ligands

Much effort has been made during the last decade to design lectin inhibitors as therapeutics against viral and bacterial adhesion or to control biological functions. The chemical strategy adopted generally consists in the tethering of several binding epitopes on a common scaffold. The resulting multivalent glycoconjugates often display a much higher binding affinity for their targets compared to their monovalent counterparts, a phenomenon designed as the "cluster" or "multivalent effect". Hundreds of multimeric architectures have been designed so far and some of the compounds displayed impressive gains in binding affinity or in vivo efficiency. Progress in this area is, however, hampered by the difficulty to predict the potency of the new multimeric inhibitors. This review presents the recent efforts to probe the important structural features of the synthetic multivalent glycoconjugates for a tight binding with specific lectins. We hope that the reported examples will aid the reader to design efficient multivalent ligands in a more predictable way.     

Amidrazones 10. Stevens rearrangement of 1-benzyl and 1-allyl-substituted-3-amino-4,5-dihydro-1-phenyl-1H-pyrazolium bromides

2-Benzyl-3-imino-1-phenylpyrazolidine (5a) and 2-allyl-3-imino-1-phenylpyrazolidine (5b) are obtained by the base-promoted rearrangement of the title compounds (4a and 4b).     

Ferrocenyl‐Coupled N‐Heterocyclic Carbene Complexes of Gold(I): A Successful Approach to Multinuclear Anticancer Drugs

Four gold(I) carbene complexes featuring 4‐ferrocenyl‐substituted imidazol‐2‐ylidene ligands were investigated for antiproliferative and antivascular properties. They were active against a panel of seven cancer cell lines, including multidrug‐resistant ones, with low micromolar or nanomolar IC₅₀ (72 h) values, according to their lipophilicity and cellular uptake. The delocalized lipophilic cationic complexes 8 and 10 acted by increasing the reactive oxygen species in two ways: through a genuine ferrocene effect and by inhibiting the thioredoxin reductase. Both complexes gave rise to a reorganization of the F‐actin cytoskeleton in endothelial and melanoma cells, associated with a G1 phase cell cycle arrest and a retarded cell migration. They proved antiangiogenic in tube formation assays with endothelial cells and vascular‐disruptive on real blood vessels in the chorioallantoic membrane of chicken eggs. Biscarbene complex 10 was also tolerated well by mice where it led to a volume reduction of xenograft tumors by up to 80 %.     

Exciton trapping, binding and diamagnetic shift in T-shaped quantum wires

We determine the exciton states of T-shaped quantum wires. We use anisotropic effective-mass models to describe the electron and hole states. Pair correlation along the wire axis and in the lateral directions is included. We accurately model the measured redshifts between exciton photoluminescence in quantum wells and T-shaped wires. This redshift arises from enhanced exciton binding and the difference between well and wire confinement energy. We predict a large enhancement of binding energy only when lateral correlation is included, indicating that T-shaped wires arequasirather thanquantum1D wires. We calculate exciton shapes and diamagnetic shifts to determine how the exciton is distorted when confined in a T-wire.     

Elastic scattering loss of atoms from colliding bose-einstein condensate wave packets

Bragg diffraction of atoms by light waves can create high momentum components in a Bose-Einstein condensate. Collisions between atoms from two distinct momentum wave packets cause elastic scattering that can remove a significant fraction of atoms from the wave packets and cause the formation of a spherical shell of scattered atoms. We develop a slowly varying envelope technique that includes the effects of this loss on the condensate dynamics described by the Gross-Pitaevski equation. Three-dimensional numerical calculations are presented for two experimental situations: passage of a moving daughter condensate through a nonmoving parent condensate, and four-wave mixing of matter waves.     

In Process Citation

Oxidation of 6-methoxyquinoline with vanadate shows the possibility of initial complex formation between the dioxovanadium(V) ion VO⁺₂ and the ethereal oxygen atom. The opening of the homocycle yields mainly 2-pyridone-3-carboxylic acid. In the case of quinine or mefloquine, the VO⁺₂ ion preferentially forms a pentagonal chelate with the secondary alcohol function. Oxidation of this complex initially produces quinoline-4-carboxylic acids. The acid that results from mefloquine is stable in the reaction solution and this property allows a reproducible consumption of reagent and a quantitative determination of this new antimalarial drug.     

Quantum logic via the exchange blockade in ultracold collisions

A nuclear spin can act as a quantum switch that turns on or off ultracold collisions between atoms even when there is neither interaction between nuclear spins nor between the nuclear and electron spins. This "exchange blockade" is a new mechanism for implementing quantum logic gates that arises from the symmetry of composite identical particles, rather than direct coupling between qubits. We study the implementation of the entangling sqrt SWAP gate based on this mechanism for a model system of two atoms, each with ground electronic configuration 1S0, spin 1/2 nuclei, and trapped in optical tweezers. We evaluate a proof-of-principle protocol based on adiabatic evolution of a one-dimensional double Gaussian well, calculating fidelities of operation as a function of interaction strength, gate time, and temperature.     

Controlled production of subradiant states of a diatomic molecule in an optical lattice

We report the successful production of subradiant states of a two-atom system in a three-dimensional optical lattice starting from doubly occupied sites in a Mott insulator phase of a quantum gas of atomic ytterbium. We can selectively produce either a subradiant 1(g) state or a superradiant 0(u) state by choosing the excitation laser frequency. The inherent weak excitation rate for the subradiant 1(g) state is overcome by the increased atomic density due to the tight confinement in a three-dimensional optical lattice. Our experimental measurements of binding energies, linewidth, and Zeeman shift confirm the observation of subradiant levels of the 1(g) state of the Yb(2) molecule.