From self-inclusion and host-guest complexes to channel structures

Mario Cetina

Department of Applied Chemistry, Faculty of Textile Technology, University of Zagreb,
Prilaz baruna Filipovića 28a, HR-10000 Zagreb, Croatia; E-mail: mario.cetina@ttf.hr

Multiple hydrogen-bonding interactions are widely used for the design of self-assembled structures capable of molecular encapsulation. For instance, intramolecular hydrogen bonds are responsible for the concave nature of resorcinarenes, thus enhancing their ability to act as host compounds for several guest molecules. Alongside intramolecular interactions, intermolecular hydrogen bonds are responsible for the building of several complicated self-assembled structures involving resorcinarenes with a variety of ionic and neutral guests leading to dimeric assemblies or host-guest complexes. In this lecture, a series of crystal structures of N-alkylammonium resorcinarenes will be presented, having both halides and large non-spherical anions (e.g. triflate and picrate) as counteranions. These structures have a flower-like shape and a cavity of suitable size for accepting small guests, thus offering promises as an interesting novel family of compounds for inclusion studies.

Furthermore, the design of molecules capable of self-assembling by weak, noncovalent interactions to form well-defined higher-order architectures is also an attractive tool for the development of advanced materials with novel properties. Thus, the synthesis and characterization of molecular cages and capsules, spheres and tubes have attracted significant interest and led to many efforts aimed at the development of novel materials. Of particular interest are inclusion complexes with channels or pores in the crystalline state because of their unique potential capabilities in gas storage, ion exchange and catalysis. Solvates of palladium(II) pincer chloride and bromide complexes prefer to interact with themselves via very weak hydrophobic interactions. In this lecture will be shown that they form channels, and thus structures which are completely different from those of pure palladium(II) pincer complexes containing terminal metal halides (chloride, bromide and iodide).