We report the discovery of a facile transformation between perfluoroaromatic molecules and a cysteine thiolate, which is arylated at room temperature. This new approach enabled us to selectively modify cysteine residues in unprotected peptides, providing access to variants containing rigid perfluoroaromatic staples. This stapling modification performed on a peptide sequence designed to bind the C-terminal domain of an HIV-1 capsid assembly polyprotein (C-CA), showed enhancement in binding, cell permeability, and proteolytic stability properties, as compared to the unstapled analog. Importantly, chemical stability of the formed staples allowed us to use this motif in the native chemical ligation mediated synthesis of a small protein affibody that is capable of binding the Human Epidermal Growth Factor 2 (HER-2) receptor.

Transition-metal based reactions have found wide use in organic synthesis and are used frequently to functionalize small molecules.1,2 However, there are very few reports of using transition-metal based reactions to modify complex biomolecules3,4, which is due to the need for stringent reaction conditions (for example, aqueous media, low temperature, and mild pH) and the existence of multiple, reactive functional groups found in biopolymers. Here we report that palladium(II) complexes can be used for efficient and highly selective cysteine conjugation reactions. The bioconjugation reaction is rapid and robust under a range of biocompatible reaction conditions. The straightforward synthesis of the palladium reagents from diverse and easily accessible aryl halide and trifluoromethanesulfonate precursors makes the method highly practical, providing access to a large structural space for protein modification. The resulting aryl bioconjugates are stable towards acids, bases, oxidants, and external thiol nucleophiles. The broad utility of the new bioconjugation platform was further corroborated by the synthesis of new classes of stapled peptides and antibody-drug conjugates. These palladium complexes show potential as a new set of benchtop reagents for diverse bioconjugation applications.

Infinite coordination polymer particles (ICPs) represent an area of growing interest in chemistry and materials science due to their unique and highly tailorable properties. These structures can be conveniently synthesized in high yields from the appropriate metal salts and bifunctional ligand precursors. Unlike conventional metal-organic framework materials (MOFs), these ICPs exhibit a higher level of structural tailorability, including size- and morphology-dependent properties, and therefore, the promise of a wider scope of utility. A variety of methods now exist for making numerous compositions, with modest control over particle size and shape. These structures can exhibit microporosity, tunable fluorescence, magnetic susceptibility, and unusual catalytic activity and selectivity. Perhaps most importantly, many of these ICP structures can be depolymerized (sometimes reversibly) much faster and under milder conditions than MOFs, which makes them attractive for a variety of biomedical applications. Thus far, several types of ICPs have been explored as contrast agents for magnetic resonance imaging and drug delivery systems. The groundwork for this emerging field of ICPs has been laid only in the past few years, yet significant advances have already been made. Indeed, this tutorial review introduces the reader to the field of ICPs, providing a guide to the work done so far, with an emphasis on synthesis, applications and future prospects.

One of the most effective ways to tune the electronic properties of conjugated polymers is to dope them with small-molecule oxidizing agents, creating holes on the polymer and molecular anions. Undesirably, strong electrostatic attraction from the anions of most dopants localize the holes created on the polymer, reducing their mobility. Here, we employ a new strategy utilizing a substituted boron cluster as a molecular dopant for conjugated polymers. By designing the cluster to have a high redox potential and steric protection of the corelocalized electron density, we obtain highly delocalized polarons with mobilities equivalent to films doped with no anions present. AC Hall effect measurements show that P3HT films doped with our boron clusters have conductivities and polaron mobilities roughly an order of magnitude higher than films doped with F 4 TCNQ, even though the boron-cluster-doped films have poor crystallinity. Moreover, the number of free carriers approximately matches the number of boron clusters, yielding a doping efficiency of ∼100%. These results suggest that shielding the polaron from the anion is a critically important aspect for producing high carrier mobility, and that the high polymer crystallinity required with dopants such as F 4 TCNQ is primarily to keep the counterions far from the polymer backbone.

Separation of CO(2)/CH(4) mixtures was studied in carborane-based metal-organic framework materials with and without coordinatively unsaturated metal sites; high selectivities for CO(2) over CH(4) ( approximately 17) are obtained, especially in the material with open metal sites.