Microstructured Magnetoactive Elastomers for Switchable Wettability.

We demonstrate the control of wettability of non-structured and microstructured magnetoactive elastomers (MAEs) by magnetic field. The synthesized composite materials have a concentration of carbonyl iron particles of 75 wt.% (≈27 vol.

Reconfigurable Surface Micropatterns Based on the Magnetic Field-Induced Shape Memory Effect in Magnetoactive Elastomers.

A surface relief grating with a period of 30 µm is embossed onto the surface of magnetoactive elastomer (MAE) samples in the presence of a moderate magnetic field of about 180 mT. The grating, which is represented as a set of parallel stripes with two different amplitude reflectivity coefficients, is detected via diffraction of a laser beam in the reflection configuration. Due to the magnetic-field-induced plasticity effect, the grating persists on the MAE surface for at least 90 h if the magnetic field remains present.

Molecular recognition of a lipophilic guanosine derivative in Langmuir films at the air-water interface.

Molecular recognition of a lipophilic deoxyguanosine derivative at the air-water interface was investigated by film balance experiments and Brewster Angle Microscopy. Results showed that guanosine, despite strong tendency towards self-assembly, interacts with both complementary and noncomplementary liponucleosides (lipophilic derivatives of deoxycytidine and deoxythymidine). At surface pressures below 17mN/m, attractive and repulsive interactions were present in case of both mixed monolayers and were the strongest at guanosine molar fractions of 0.

Ion-specific self-assembly of a lipophilic guanosine derivative in thin surface films.

We investigated the effect of various ions on the surface assembly of a guanosine derivative with one hexadecanoyl chain at the air-water interface. The ions were added to the water subphase prior to spreading of the surface film. Like in bulk water, also at the air-water interface, K(+) ions exhibit the strongest influence on the assembly features as they induce structural transformation from lamellar to mosaic-like assembly.

Lamellar versus compact self-assembly of lipoguanosine derivatives in thin surface films.

We performed a comparative study on the self-assembling properties of four guanosine derivatives with one and two lipophilic chains of two different lengths at the air-water interface and after Langmuir-Blodgett (LB) deposition onto various solid supports (mica, silicon wafer, graphite). At the air-water interface the derivatives with one lipophilic chain exhibit surface compression behaviour with a profound first order phase transition from the liquid-expanded to the liquid-condensed phase. They assemble into lamellar surface formations, whose structural characteristics remain practically unmodified after their transfer onto the solid substrates.

Two novel ternary dicopper(II) μ-guanazole complexes with aromatic amines strongly activated by quantum dots for DNA cleavage.

Two novel (μ-guanazole)-bridged binuclear copper(II) complexes with 1,10-phenanthroline (phen) or 2,2'-bipyridine (bipy), [Cu2(μ-N2,N4-Hdatrz)(phen)2(H2O)(NO3)4] (1) and [Cu2(μ-N1,N2-datrz)2(μ-OH2)(bipy)2](ClO4)2 (2) (Hdatrz = 3,5-diamino-1,2,4-triazole = guanazole), have been prepared and characterized by X-ray diffraction, spectroscopy, and susceptibility measurements. Compounds 1 and 2 differ in the aromatic amine, which acts as a coligand, and in the Cu···Cu'-bridging system. Compound 1, which contains two mono-bridged copper ions, represents the first example of a discrete Cu-(NCN-trz)-Cu' complex.

Liponucleoside thin films: the special behaviour of guanosine.

We performed a comparative study of self-assembling properties of liponucleoside materials containing different nucleobases in their hydrophilic headgroups, but possessing the same type of lipophilic moiety in their hydrophobic tails. Surface pressure versus area isotherms (π(A)) of monolayers formed at the air-water interface show that guanine-based materials form stable monolayer films exhibiting a profound first order phase transition from the liquid expanded to the condensed phase. Materials based on other nucleobases form less stable films exhibiting a liquid-like behaviour.