Multivalent Cucurbituril Dendrons for Cell Membrane Engineering with Supramolecular Receptors.

The affinity possible from certain supramolecular motifs rivals that for some of the best-recognized interactions in biology. Cucurbit[7]uril (CB[7]) macrocycles, for example, are capable of achieving affinities in their binding to certain guests that rival that of biotin-avidin. Supramolecular host-guest recognition between CB[7] and certain guests has been demonstrated to spatially localize guest-linked agents to desired sites in vivo, offering opportunities to better exploit this affinity axis for applications in biomedicine. Herein, architectures of CB[7] are prepared from a polyamidoamine (PAMAM) dendrimer scaffold, installing a PEG-linked cholesterol anchor on the opposite end of the dendron to facilitate cell membrane integration. Cells are then modified with this dendritic CB[7] construct in vitro, demonstrating the ability to deliver a model guest-linked agent to the cell membrane. This approach to realize synthetic supramolecular "membrane receptors" may be leveraged in the future for in situ imaging or modulation of cell-based therapies or to facilitate a synthetic supramolecular recognition axis on the cell membrane.

Transition metal-free hydrodefluorination of acid fluorides and organofluorines by Ph3GeH promoted by catalytic [Ph3C][B(C6F5)4].

It has been shown that the germane Ph3GeH converts aryl and aliphatic acid fluorides directly to their corresponding aldehydes without over-reduction via the conversion of Ph3GeH to the germylium cation [Ph3Ge]+ by a catalytic amount of the tritylium salt [Ph3C][B(C6F5)4]. Here, no transition metal catalyst is required and there is no decarbonylation of the acid fluoride, which are advantages over existing methods. The fluorine atoms can also be abstracted from organofluorine compounds using this method.