Site-specific conjugation of 8-ethynyl-BODIPY to a protein by [2 + 3] cycloaddition.

We report a straightforward synthesis of 8-ethynyl-BODIPY derivatives and their potential as fluorescent labeling compounds using an alkyne-azide click chemistry approach. The ethynyl substituted BODIPY dyes at the meso-position were reacted under Cu(+) catalysis and mild physiological conditions in organic and biological model systems using benzyl azide and a Barstar protein which was selectively modified by a single amino acid substituted methionine at the N-terminus (Met1) → azidohomoalanine (Aha). Conjugation with the protein and the model azide was indicated by a significant blue shift upon formation of the triazole moiety system, which allowed easy distinction between free and coupled dyes.

Synthesis and mechanical properties of organic-inorganic hybrid materials from lignin and polysiloxanes.

The preparation of silica-containing organic-inorganic hybrid materials composed of kraft lignin, alkoxysilanes, and organic linkers was investigated. 3-Glycidyloxypropyltrimethoxysilane, 3-(triethoxysilyl)propylisocyanate (IPTES), and bis(trimethoxysilyl)hexane were selected as the most promising linkers. The best materials obtained showed improved mechanical and thermal properties compared with lignin itself.