Synthesis and Surface Behaviour of NDI Chromophores Mounted on a Tripodal Scaffold: Towards Self-Decoupled Chromophores for Single-Molecule Electroluminescence.

This paper reports the efficient synthesis, absorption and emission spectra, and the electrochemical properties of a series of 2,6-disubstituted naphthalene-1,4,5,8-tetracarboxdiimide (NDI) tripodal molecules with thioacetate anchors for their surface investigations. Our studies showed that, in particular, the pyrrolidinyl group with its strong electron-donating properties enhanced the fluorescence of such core-substituted NDI chromophores and caused a significant bathochromic shift in the absorption spectrum with a correspondingly narrowed bandgap of 1.94 eV. Cyclic voltammetry showed the redox properties of NDIs to be influenced by core substituents. The strong electron-donating character of pyrrolidine substituents results in rather high HOMO and LUMO levels of -5.31 and -3.37 eV when compared with the parental unsubstituted NDI. UHV-STM measurements of a sub-monolayer of the rigid tripodal NDI chromophores spray deposited on Au(111) show that these molecules mainly tend to adsorb flat in a pairwise fashion on the surface and form unordered films. However, the STML experiments also revealed a few molecular clusters, which might consist of upright oriented molecules protruding from the molecular island and show electroluminescence photon spectra with high electroluminescence yields of up to 6×10-3 . These results demonstrate the promising potential of the NDI tripodal chromophores for the fabrication of molecular devices profiting from optical features of the molecular layer.

Cyclodextrin-Polypyrrole Coatings of Scaffolds for Tissue Engineering.

Polypyrrole is one of the most investigated conductive polymers used for tissue engineering applications because of its advantageous properties and the ability to promote different cell types' adhesion and proliferation. Together with ß-cyclodextrin, which is capable of accommodating helpful biomolecules in its cavity, it would make a perfect couple for use as a scaffold for tissue engineering. Such scaffolds were prepared by the polymerisation of 6-(pyrrol-3-yl)hexanoic acid on polycaprolactone microfibres with subsequent attachment of ß-cyclodextrin on the polypyrrole layer. The materials were deeply characterised by several physical and spectroscopic techniques. Testing of the cyclodextrin enriched composite scaffold revealed its better performance in in vitro experiments compared with pristine polycaprolactone or polypyrrole covered polycaprolactone scaffolds.

Regioselective halogenation of thiacalix[4]arenes in the cone and 1,3-alternate conformations.

Monohalogenation of thiacalix[4]arene in the cone conformation gave either the meta- or para-substituted isomers depending on the halogen and reaction conditions used. Surprisingly, the same reaction with the 1,3-alternate conformer led only to the meta isomer. This is the first example of such a conformation-dependent regioselectivity in calixarene/thiacalixarene chemistry. As the halogen-substituted calixarenes are useful synthetic intermediates, this provided the unique opportunity to functionalize the basic skeleton at two different positions.