Three Efficient Methods for Preparation of Coelenterazine Analogues

The growing popularity of bioluminescent assays has highlighted the need for coelenterazine analogues possessing properties tuned for specific applications. However, the structural diversity of known coelenterazine analogues has been limited by current syntheses. Known routes for the preparation of coelenterazine analogues employ harsh reaction conditions that limit access to many substituents and functional groups. Novel synthetic routes reported here establish simple and robust methods for synthesis and investigation of structurally diverse marine luciferase substrates. Specifically, these new routes allow synthesis of coelenterazine analogues containing various heterocyclic motifs and substituted aromatic groups with diverse electronic substituents at the R² position. Interesting analogues described herein were characterized by their physicochemical properties, bioluminescent half‐life, light output, polarity and cytotoxicity. Some of the analogues represent leads that can be utilized in the development of improved bioluminescent systems.     

Effect of weathering on scratch/mar and mechanical behaviour of clearcoats

The study examines the effect of weathering on mechanical and chemical properties of two 2K (twopack, with and without light stabilisation additives) and one 1K (onepack) clearcoats, concentrating on scratch and mar resistance and acid etch resistance. The clearcoats were investigated before and in the course of accelerated weathering. For determining the mar resistance two different instruments were used: - AMTEC laboratory car wash equipment (rotating wet brush) - Crockmeter Explanations for the changes in clearcoat properties caused by weathering are given by Dynamic-Mechanical Analysis, FT-IR-Spectroscopy, Universal-hardness and surface tension measurements. The clearcoat systems investigated show a clear deterioration of their properties after short periods of accelerated weathering. This effect is more expressed for the clearcoat samples without light stabilizers.