Resorcinarene Bis‐Thiacrowns: Prospective Host Molecules for Silver Encapsulation

Mixed‐donor atom tetramethoxy resorcinarene bis‐thiacrown hosts, in which the crown unit contains both hard oxygen and soft sulfur donor atoms, were synthesized for soft metal cation binding. The binding properties were investigated both in solution and in the solid state by NMR spectroscopy and X‐ray crystallography. It was found that the resorcinarene bis‐thiacrowns were able to complex silver cations with remarkable affinity forming readily 1:2 host–guest complexes in solution. The solid state structures also revealed that the bis‐thiacrowns form silver complexes in an unanticipated endo‐ and exo‐cavity fashion within the same host molecule. Both the solution and solid state studies indicated the sulfur atoms to be the major contributing donor atoms in forming the binding interactions with silver cations.     

Staying alive: new perspectives on cell immobilization for biosensing purposes

Intact living cells, because of their simplicity of use and their ability to provide highly valuable functional information, are well suited to biosensing applications. Cells can be genetically engineered by introduction of reporter proteins, modified to achieve analyte selectivity for their sensing capabilities, and connected to a transducer to obtain whole-cell biosensors. These bioanalytical features are increasingly attracting attention in the pharmaceutical, environmental, medical, and industrial fields. Whole-cell biosensors based on different recognition elements and transduction mechanisms have been also incorporated into portable devices and, with recent advances in micro and nanofabrication and microfluidics technology, miniaturized to achieve single-cell level analysis. Cell immobilization, widely used in, for example, microbial biofermentors or bioremediation systems, is now emerging as an appealing way of integrating whole-cell biosensors into devices, to maintain long-term cell viability, to increase the reproducibility of the cell’s response, and to avoid the spread of genetically modified cells into the environment, the latter being very important when devices are used for analysis in the field. A plethora of materials and functionalized surfaces have been proposed for immobilization of microbial or mammalian cells, each one having peculiar advantages and limitations. This critical review highlights and discusses recent trends, together with selected bioanalytical applications of immobilized viable cells. In particular the review focuses on some aspects that seem to hold great promise for future applications of immobilized cells, spanning from microbial biosensors to microbial biofilms, cell microarrays, and single-cell analysis.     

Dynamic mapping of CN rotation following photoexcitation of ICN-

In a spin: the dynamics of photoexcited ICN(-) (Ar)(0-5) are presented. Photodetachment produces quasi-thermal electron emission that leaves ICN with up to 2.85 eV of internal energy. Photodissociation at 2.5 eV leads to one-atom caging and highly solvated anion products. Calculations indicate efficient energy transfer into CN rotation upon excitation to the (2)Π(1/2) excited state. CN rotation is vital to explain the unique dynamics observed.     

Intramolecular cyclization of alkoxyaminosugars: access to novel glycosidase inhibitor families

We report the synthesis of two novel families of iminosugars as glycosidase inhibitors involving an intramolecular cyclization between an N-alkoxyamino group and a latent aldehyde of a reducing sugar as the key step. Using this methodology we have prepared the hitherto unknown bicyclic polyhydroxylated N-(methoxy, benzyloxy)anhydroazepanes and N-benzyloxy-d-xylonojirimycin; all these novel compounds turned out to be moderate β-glucosidase inhibitors in a pH-dependent manner.     

Slow relaxation of the magnetization in non-linear optical active layered mixed metal oxalate chains

New Co(II) members of the family of multifunctional materials of general formula [DAMS](4)[M(2)Co(C(2)O(4))(6)]·2DAMBA·2H(2)O (M(III) = Rh, Fe, Cr; DAMBA = para-dimethylaminobenzaldehyde and [DAMS(+)] = trans-4-(4-dimethylaminostyryl)-1-methylpyridinium) have been isolated and characterized. Such new hybrid mixed metal oxalates are isostructural with the previously investigated containing Zn(II), Mn(II), and Ni(II). This allows to preserve the exceptional second harmonic generation (SHG) activity, due to both the large molecular quadratic hyperpolarizability of [DAMS(+)] and the efficiency of the crystalline network which organizes [DAMS(+)] into head-to-tail arranged J-type aggregates, and to further tune the magnetic properties. In particular, the magnetic data of the Rh(III) derivative demonstrate that high spin octacoordinated Co(II) centers behave very similarly to the hexacoordinated Co(II) ones, being dominated by a large orbital contribution. The Cr(III) derivative is characterized by ferromagnetic Cr(III)-Co(II) interactions. Most relevantly, the Fe(III) compound is characterized by a moderate antiferromagnetic interaction between Fe(III) and Co(II), resulting in a ferrimagnetic like structure. Its low temperature dynamic magnetic properties were found to follow a thermally activated behavior (τ(0) = 8.6 × 10(-11) s and ΔE = 21.4 K) and make this a candidate for the second oxalate-based single chain magnet (SCM) reported up to date, a property which in this case is coupled to the second order non linear optical (NLO) ones.     

A quasistatic evolution model for perfectly plastic plates derived by Γ-convergence

The subject of this paper is the rigorous derivation of a quasistatic evolution model for a linearly elastic–perfectly plastic thin plate. As the thickness of the plate tends to zero, we prove via Γ-convergence techniques that solutions to the three-dimensional quasistatic evolution problem of Prandtl–Reuss elastoplasticity converge to a quasistatic evolution of a suitable reduced model. In this limiting model the admissible displacements are of Kirchhoff–Love type and the stretching and bending components of the stress are coupled through a plastic flow rule. Some equivalent formulations of the limiting problem in rate form are derived, together with some two-dimensional characterizations for suitable choices of the data.     

Small noise asymptotic expansions for stochastic PDE’s driven by dissipative nonlinearity and Lévy noise

We study a reaction–diffusion evolution equation perturbed by a space–time Lévy noise. The associated Kolmogorov operator is the sum of the infinitesimal generator of a _C0$C_0$-semigroup of strictly negative type acting on a Hilbert space and a nonlinear term which has at most polynomial growth, is non necessarily Lipschitz and is such that the whole system is dissipative.