We present the STM investigation of four different oligopyridines at the liquid/highly oriented pyrolytic graphite interface. The heteroaromatic compounds are constitutional isomers showing the same overall shape regardless of their actual conformation. On the basis of weak intermolecular C-H...N hydrogen-bonding interactions, different nanopatterns are formed following a simple general concept for the two dimensional self-assembly. The molecules arrange either in linear or in cyclic structures. Though the oligopyridines are achiral, the formation of prochiral trimeric superstructures leads to chiral phases due to the immobilization on the surface. Some of the molecules show polymorphic structures depending on the solvent. The large variety of the presented structures formed by self-assembly of the different oligopyridines which retain the same functional heteroaromatic backbone shall open the possibility of exploiting these patterns as templates for the nanostructuring of surfaces with guests such as small molecules or metal ions for intriguing applications in, for example, catalysis.

We describe a versatile method to obtain functional hollow nanoreactors with a hydrophilic liquid core. The synthesis of hollow polyurea, polythiourea, and polyurethane nanocapsules was performed by interfacial polycondensation or cross-linking reactions in inverse miniemulsion. The miniemulsions were built upon emulsification of a solution of amines or alcohols in a polar solvent with cyclohexane as the nonpolar continuous phase. The addition of suitable hydrophobic diisocyanate or diisothiocyanate monomers to the continuous phase allows the polycondensation or the cross-linking reactions to occur at the interface of the droplets. The wall thickness of the capsules can be directly tuned by the quantity of the reactants. The nature of the monomers and the continuous phase are the critical factors for the formation of the hollow capsules, which is explained by the interfacial properties of the system. The resulting polymer nanocapsules could be subsequently dispersed in water. The capsules were found to be spherical when formamide was used as the liquid core, whereas elongated capsules were obtained with water. Finally, we used these hollow nanoreactors as a model system for the preparation of silver nanoparticles by reducing silver nitrate solutions encapsulated by the polyurea shell. These syntheses are the first that allow the encapsulation of hydrophilic compounds in miniemulsion in a hollow structure.

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The preparation of nanoparticles in a soap-free system is highly attractive, as surfactants may influence and deteriorate subsequent applications. Thereby, the assembly of solid particles on droplets/particles is well known as Pickering-type stabilization. The resulting hybrid nanocomposites offer in general a rough surface and are highly intriguing for potential drug delivery systems, coating applications, and so forth. This review highlights developments in production and application of Pickering-type nanoparticles synthesized via heterophase polymerization techniques in emulsion, miniemulsion, dispersion, and suspension. We will focus our discussion on systems, wherein stabilization of the final nanometer-sized hybrids is exclusively accomplished via particle stabilizers. In case surfactants are used during preparation, they only serve as pre-treating agents to modify the surface properties of the particle stabilizer, and not being employed for the purpose of droplet/particle stabilization.

A bisterpyridine based molecule, 3,3′-BTP, shows a variety of adlayer structures at the interface between highly oriented pyrolytic graphite (HOPG) and the liquid depending on the concentration in solution. Three closely related linear and one hexagonal 2D patterns are found. Comparison with the self-assembly at the HOPG|gas interface shows that in the absence of the solvent one of the linear and the hexagonal structures can be found. The concentration dependent order of appearance of the different surface structures is rationalized by a thermodynamic model. In the adlayer unit cell, the hexagonal phase offers a central void which is mostly filled with a seventh 3,3′-BTP molecule. In the presence of the solvent, those molecules are presumably rotating, whereas at the HOPG|gas interface no clear rotation can be observed.