Shedding light on the mitochondrial matrix through a functional membrane transporter.

The first fluorescent probes that are actively channeled into the mitochondrial matrix by a specific mitochondrial membrane transporter in living cells have been developed. The new functional probes (BCT) have a minimalist structural design based on the highly efficient and photostable BODIPY chromophore and carnitine as a biotargeting element. Both units are orthogonally bonded through the common boron atom, thus avoiding the use of complex polyatomic connectors. In contrast to known mitochondria-specific dyes, BCTs selectively label these organelles regardless of their transmembrane potential and in an enantioselective way. The obtained experimental evidence supports carnitine-acylcarnitine translocase (CACT) as the key transporter protein for BCTs, which behave therefore as acylcarnitine biomimetics. This simple structural design can be readily extended to other structurally diverse starting F-BODIPYs to obtain BCTs with varied emission wavelengths along the visible and NIR spectral regions and with multifunctional capabilities. BCTs are the first fluorescent derivatives of carnitine to be used in cell microscopy and stand as promising research tools to explore the role of the carnitine shuttle system in cancer and metabolic diseases. Extension of this approach to other small-molecule mitochondrial transporters is envisaged.

Stereochemical and Steric Control of Photophysical and Chiroptical Properties in Bichromophoric Systems.

Stereochemical and steric control of the relative spatial arrangement of the chromophoric units in multichromophoric systems offers an interesting strategy for raising unusual and appealing light-induced emission states. To explore and exploit this strategy, a series of conformationally restricted boron-dipyrromethene (BODIPY) dimers were designed by using tartaric acid as a symmetrical connector between the boron atoms of the dyes. The variety of stereoisomeric forms available for this bis(hydroxy acid) allows the relative spatial orientation of the chromophoric units in the dimer to be modified, which thus opens the door to modulation of the photophysical and chiroptical properties of the new bichromophoric systems. Chromophore alkylation introduces an additional level of control through distance-dependent steric interactions between the BODIPY units in the dimer, which also modulates their relative spatial disposition and properties.

Efficient multi-click approach to well-defined two-faced octasilsesquioxanes: the first perfect Janus nanocube.

The preparation of the first structurally well-defined Janus nanocube showing two chemically distinct opposed faces is described. The synthetic approach is based on a highly efficient and symmetry-controlled CuAAC functionalization of an octa-azido cubic silsesquioxane with a conformationally constrained tetra-alkyne with an appropriate spatial orientation of the triple bonds.