Study of π-π, cation-π and hydrogen bonding interactions in liquid crystalline materials and weakly bound organic metal complexes

We are interested in the use of non-covalent interactions for improved control over materials properties. This includes π-π interaction between stacked π-systems, cation-π interactions between unsaturated molecules and transition metals, and hydrogen bonding.

The combination of hydrogen-bonding and π-π interactions is the theme of our research in H-bond stabilized liquid crystals.  Here we aim to combine high columnar ordering with tailor-made degrees of stabilization by H-bonding.  Such materials can play a role in a variety of opto-electronic applications.

Generalized structure of monofunctional HAT6 structure, and a typical texture of a columnar discotic liquid crystal material as observed by optical microscopy.

A parallel study of a series of new unsymmetrically substituted HAT6 derivatives has been realized within our group. The results of this work, presented during International Liquid Crystals Conference, Slovenia – ILCC 2004, indicate the importance of Van der Waals interactions (interdigitation phenomena) on the stability of the Colh mezophase, and directly on the degree of ordering in the investigated systems.

Molecular modeling calculations are also been used in our group (Materials Studio 2.2 – Accelrys) to build up the periodical structures of the investigated discotic columnar liquid-crystalline materials.

Cation-π interactions are of interest for both fundamental and applied studies.  We have e.g. studied the interaction of Ag(I) [JPC2002] and Cu(II) [Orglett2003] with unsaturated substrates (alkenes, aromatic moieties) via computational means, and have applied our knowledge in the field to the enantiomeric separation of amino acids [Theo’s ref].

Recently we have started an STW-sponsored project together with prof. Andre de Haan (University of Twente) to further investigate and optimize such interactions for application in large-scale separation process.

Current co-workers: Ioan Paraschiv and  Ruud Cuypers.

Most of these ‘soft interaction’-topics only flourish due to the intense collaboration with dr. Ton Marcelis.