BODIPYs with Photoactivatable Fluorescence

The borondipyrromethene (BODIPY) chromophore is a versatile platform for the construction of photoresponsive dyes with unique properties. Specifically, its covalent connection to a photocleavable group can be exploited to engineer compounds with photoswitchable fluorescence. The resulting photoactivatable fluorophores can increase their emission intensity or shift their emission wavelengths in response to switching. Such changes permit the spatiotemporal control of fluorescence with optical stimulations and the implementation of imaging strategies that would be impossible to replicate with conventional fluorophores. Indeed, BODIPYs with photoactivatable fluorescence enable the selective highlighting of intracellular targets, the nanoscaled visualization of sub-cellular components, the real-time monitoring of dynamic events and the photochemical writing of optical barcodes.     

Formal Gold‐to‐Gold Transmetalation of an Alkynyl Group Mediated by Palladium: A Bisalkynyl Gold Complex as a Ligand to Palladium

The reaction of [Au(C?C?n‐Bu)]_n with [Pd(η³‐allyl)Cl(PPh₃)] results in a ligand and alkynyl rearrangement, and leads to the heterometallic complex [Pd(η³‐allyl){Au(C?C?n‐Bu)₂}]₂ ( 3 ) with an unprecedented bridging bisalkynyl–gold ligand coordinated to palladium. This is a formal gold‐to‐gold transmetalation that occurs through reversible alkynyl transmetalations between gold and palladium.     

The hetero-Diels-Alder addition of sulfur dioxide: the pseudo-chair conformation of a 4,5-dialkylsultine

Even unsubstituted butadiene adds to sulfur dioxide in the hetero-Diels-Alder mode more rapidly than in the chelotropic mode. The sultine can be observed in equilibrium with the diene and the sulfur dioxide only at low temperature and in the presence of CF(3)COOH. Crystals of 4,5-dialkyl-sultine resulting from the SO(2) addition to 1,2-dimethylidenecyclohexane have been obtained at -100 degrees C and analyzed by X-ray diffraction. Quantum chemical calculations have shown that hyperconjugative interactions within the sulfinyl moiety are responsible for the anomeric effects observed in sultines that prefer pseudo-chair conformations with pseudo-axial Sdbond;O bonds.