The three-dimensional structure of dendrimers with a nucleus, an interior with cavities, and a surface often supplied with functional groups gives rise to increasing interest in those molecules as new materials,[',2] e.g. for medical and pharmaceutical applications, as 'dendritic boxes' for dyes and radicals, as ligands for metal complexation, or as compounds with liquid crystalline behavior. Furthermore, their specific physical properties, e.g. low bulk viscosities due to the absence of entanglements, make them interesting candidates for modifying rheological and mechanical properties of In this frame, dendritic mesogens are, in addition to main chain liquid crystalline polymers (MCLCPs) and side-chain liquid crystalline polymers (SCLCPs), an interesting third group of liquid crystalline polymers (LCPs). Besides species with a hypcrbranched structure or a dendron skeleton, liquid crystalline compounds with a perfect dendrimeric architecture (liquid crystalline dendrimers in the strict sense,

A sphere of a ferrogel is exposed to a homogeneous magnetic field. In accordance to theoretical predictions, it gets elongated along the field lines. The time-dependence of the elastic shear modulus causes the elongation to increase with time analogously to mechanic creep experiments, and the rapid excitation causes the sphere to vibrate. Both phenomena can be well described by a damped harmonic oscillator model. By comparing the elongation along the field with the contraction perpendicular to it, we can calculate Poisson's ratio of the gel. The magnitude of the elongation is compared with the theoretical predictions for elastic spheres in homogeneous fields.

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Summary: For the first time, thermoreversible ferrogels (FG) by physical gelation of ferrofluids have been described. Finavestan A80B paraffin oil in a concentration range of the gelator KRATON G‐1650 with Cgelator = 3–10 wt.‐%, was used to obtain stable and homogeneous FGs. TEM micrographs revealed that the magnetite particles are preferably located in the ‘free’ paraffin phase between micellar domains of the gelator. So, the magnetite nanoparticles make visible a ‘negative’ picture of the structure of the micellar domains of the gel, which is observed in the pure gel as a ‘positive’ image. The mean diameter of the polystyrene cores is $\overline d$ = 17 nm, and that of the magnetite particles is $\overline d$ = 7 nm.

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Liquid-crystalline derivatives of poly(propylene imine)dendrimers of the 0th, 1st and 2nd generations, complexed with copper(II) ions, were studied by EPR spectroscopy. The structures of copper (II) complexes with different Cu(II) loadings x per dendrimer ligand L (x = Cu/L) were determined. At the lowest concentration, the Cu(II) ions form monomeric complexes with approximately square-planar N2O2 coordination of both carbonyl oxygen and amido nitrogen atoms. At higher copper content, two kinds of Cu(II) complex sites with different geometries exist. The orienting effect of a high magnetic field was used to investigate the structure and magnetic properties of the copper(II) complexes. This effect, for the first time in dendrimers, allowed the resolution of five nitrogen super-hyperfine lines on g(z) components with the unusual coupling constant of a(Nz)= 35.9 x 10(-4) cm(-1). The combination of the magnetic parameters and the orienting effect indicates the presence of a monomeric complex with pseudotetrahedral N2O2 coordination of the Cu(II) ion, as well as a "dimer" structure with fivefold coordination, presumably due to an N3O2 environment. Higher copper loadings lead to increased exchange coupling between the complex sites.

To overcome some drawbacks of polyvinylpyridines, new monomers of acrylate and methacrylate type with pendant pyridine groups i.e., 4‐(3‐methacryloylpropyl)pyridine 1a and 4‐(3‐acryloylpropyl)pyridine 1b were successfully prepared, although it turned out to be challenging work to synthesize the acrylate monomer 1b. First polymerization studies showed that the new monomers could be polymerized easily by atom transfer radical polymerization (ATRP). The new polymers show excellent characteristics, such as very good solubility, low glass‐transition temperature, and easy quaternization. Design and structure of new monomers 1a and 1b.magnified imageDesign and structure of new monomers 1a and 1b.

Thermotropic metal-containing liquid crystalline compounds have enjoyed considerable attention in the last few years.['] Introducing a metal into a mesogenic molecule can result in interesting electrical and magnetic properties. The high electron density of the metallic center may lead to an increased polarizability, high birefringence, and under appropriate conditions, to enhanced nonlinear optical response. Metals with partly filled d-orbitals can be chromogenic due to low-lying electronic transitions. Moreover, metallic centers with unpaired electrons are of interest as the basis for paramagnetic liquid crystals. In recent times, different types of both calamitic and discotic metallomesogens have been found.Nitrogen donor atoms in macrocyclic metallomesogens are known in various phthalocyanine, tetrapyrazinoporphyrazine, porphyrin and dibenzotetraaza[l4]annulene complexes, which form hexagonal or rectangular columnar mesophases.f'] These discotic metal complexes contain a rigid, unsaturated core with the metal atom in most cases in or, in some examples, nearby the center of the cyclic molecule. The molecular structures are mostly square planar. caused by the tetradentate ligand.Metal-free discotic liquid crystalline compounds, containing nitrogen in the central core, exist as derivatives of phthalocyanine,[21 and p~rphyrin,'~] as well as azacrown discogens, such as derivatives of hexa~yclene,[~, '3 ' 1 cyclam,r6] triazacyclododecane and triazacyclononane.[71 On the other hand, numerous nonmesogenic metal complexes of azacrown compounds have been synthesized and characterized in the past three In addition to the above mentioned physical interest, metal complexes with saturated azamacrocyclic ligands seem to be o f important bioinorganic relevance as model compounds for the understanding of the chemistry, reactivity and spectroscopic properties of metal-containing biomolecules, e.g. metaIIopr~teins.'~' Saturated triazamacrocyclic ligands do not normally exhibit different conformers in metal complexes as in the case of ligands with larger saturated azamacrocycles.""]