The SARS coronavirus main proteinase (M(pro)) is a key enzyme in the processing of the viral polyproteins and thus an attractive target for the discovery of drugs directed against SARS. The enzyme has been shown by X-ray crystallography to undergo significant pH-dependent conformational changes. Here, we assess the conformational flexibility of the M(pro) by analysis of multiple crystal structures (including two new crystal forms) and by molecular dynamics (MD) calculations. The MD simulations take into account the different protonation states of two histidine residues in the substrate-binding site and explain the pH-activity profile of the enzyme. The low enzymatic activity of the M(pro) monomer and the need for dimerization are also discussed.

A large, symmetrically substituted triazine-based molecule, synthesized by a copper-free Sonogashira coupling procedure self-assembles to form a novel 1D channel structure that hosts chlorobenzene molecules as guests.

The reaction of LTiCl3 (1) (L = HC(CMeN(2,6-iPr2C6H3))2, nacnac) with MeLi·(Et2O)0.14 in toluene afforded the stable Ti(IV) alkyl complex LTiMe3 (1). Reaction of 1 with 2 equiv of AlMe3 in toluene resulted in the formation of LTi(Me)CH(Al2Me5) (2) in high yield. Compounds 1 and 2 were characterized by X-ray structural analysis, NMR, IR, mass spectrometry, and elemental analysis. The Ti−CH bond length (1.880(2) Å) of 2 is in the range of a short Ti−C bond. This was additionally supported by NMR and DFT calculations. Compound 2 polymerized ethylene without adding any cocatalyst, although activity is low; the best TOF value was 2.4 × 104 g(polymer)/mol catalyst·h·bar.

In addition, I was involved in cooperations leading to the following publications or manuscripts. I wish to express my kindest regards to all people involved in these studies for the productive collaborations. -A. Ranganathan, B.C. Heisen, I. Dix and F. A. Meyer (2007) A triazine-based threedirectional rigid-rod tecton forms a novel 1D channel structure. Chem Commun