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Amphiphilic self-assembly usually involves molecules consisting of hydrophobic and hydrophilic segments. Now, this concept has been broadened to encompass the self-assembly of fully hydrophobic molecules that contain mutually immiscible alkyl and π-conjugated segments. Selective additives — n-alkanes or C60 — direct their assembly into various ordered and optoelectronically functional structures.
A general and broad-ranging stereospecific coupling of secondary and tertiary boronic esters with electron-rich aromatics is reported. The reaction involves initial formation of a boronate complex followed by activation of the electron-rich aromatic moiety by an electrophile, which triggers a stereospecific 1,2-migration and subsequent elimination/re-aromatization.
Adjuvants are used to increase the immune response to molecular vaccines. A minimal synthetic variant of the saponin natural product QS-21 has been developed as a potent, non-toxic adjuvant, enabling dissection of structural requirements in the triterpene domain and in vivo biodistribution studies to probe mechanisms of action.
Proton-conducting materials have proved useful for renewable energy applications and bioelectronics technologies. The proton conductivity of thin films made from reflectin — a cephalopod structural protein — is now reported. Reflectin's electrical properties compare favourably to those of artificial materials, and have enabled the demonstration of protein-based protonic transistors.
Most cyclic conjugated molecules, such as benzene, exhibit two sides. Möbius annulenes, however, with an odd number of 180° twists in their π system, are one-sided and violate the Hückel rule. Now, using a topological trick it is demonstrated that triply twisted systems are not particularly strained and probably easier to synthesize than singly twisted ones.
The adoption of multiple conformations by proteins presents a challenge for ligand discovery using docking simulations. Now, a method for representing the conformational behaviour of a flexible protein in docking screens, which is guided by experimental crystallography data, is shown to predict protein conformation, ligand pose and aid the discovery of new ligands.
Tyrosine-kinase inhibitors (TKI) are amongst the best known examples of targeted cancer therapeutics. Now, using hyperspectral stimulated Raman scattering imaging, the label-free visualization and quantification of two TKI drugs inside living cells is reported. Significant trapping of TKI drugs in lysosomes was observed, which can be reversed by co-treatment with chloroquine through lysosome-mediated interactions.
A nanoreactor approach has now been used to investigate the substitution reactions of arsenic(III) compounds with thiols at the single-molecule level. The rates of interconversion of seven reaction components are tracked, revealing the stereochemistry of sulfur–sulfur substitution at an arsenic centre.
Selective functionalization of light hydrocarbons is a challenging but desirable transformation. Now a family of Fe(II)-based metal–organic frameworks has been shown to convert ethane into ethanol and acetaldehyde using N2O. Electronic structure calculations indicate that the active Fe oxidant in the MOF is a high-spin S = 2 iron(II)–oxo species.
Borinium ions are two-coordinate boron cations that contain only four valence electrons on boron, and are difficult to isolate without electron donation from adjacent heteroatoms. Now, diarylborinium salts with no lone-pair donation from heteroatoms have been isolated, characterized and found to participate in an unusual reaction with CO2.
(−)-Lomaiviticin A inhibits the growth of cancer cells at nanomolar to picomolar concentrations; however, the basis for this potent cytotoxicity is not known. This natural product has now been shown to induce production of DNA double-strand breaks at nanomolar concentrations. Evidence demonstrates that strand cleavage proceeds via reactive carbon-centred free radical intermediates.
Colloidal inverse bicontinuous cubic mesophases have now been formed by self-assembly of amphiphilic dendritic-linear block copolymers in solution. The internal networks of water channels provide a high surface area with tunable functional groups that can serve as anchoring points for macromolecular guests such as proteins and enzymes.
Polyene motifs are found in a large number of natural products. Now, by applying a general retrosynthetic algorithm, it has been shown that the polyene motifs found in >75% of these compounds can be synthesized using just 12 bifunctional haloalkenyl MIDA boronate building blocks and one coupling reaction.
Soft materials that can undergo a macroscopic change in response to external stimuli may prove useful for a range of biological applications. Now, it has been shown that hydrogels encapsulating active enzymes can undergo a gel–sol transition in the presence of a range of small-molecule triggers and can potentially be used as sensors or drug-delivery systems.
Carbonization of a self-assembled monolayer of a hexayne amphiphile at the air/water interface at room temperature results in the formation of functional carbon nanosheets. The nanosheets exhibit a molecularly defined thickness, are mechanically self-supporting over several micrometres, and have macroscopic lateral dimensions on the order of centimetres.
Understanding the process of exciton fission, which occurs in certain organic materials, could lead to the development of more efficient photovoltaic devices. Here, an expression derived from first principles is used to accurately characterize the singlet fission rate of a wide array of materials, reproducing a transition from weak to strong coupling as a function of molecular separation.
Strong acoustic fields applied to solutions of linear polymers typically result in mid-chain scission, yielding products half the molecular weight of the original. Now it has been shown that poly(o-phthalaldehyde), a polymer with a ceiling temperature below room temperature, undergoes chain scission and subsequent depolymerization to monomers. Introduction of an appropriate initiator to the monomer regenerates poly(o-phthaladehyde) macromolecules.
Magnetic resonance imaging of gene expression has been limited by the low molecular sensitivity of conventional 1H-MRI. To overcome this limitation, the first genetically encoded reporters for hyperpolarized xenon MRI have been developed. These expressible reporters, based on gas-filled protein nanostructures from buoyant microorganisms, are detectable at picomolar concentrations.
Controlling the self-assembly of small molecules within living animals is complicated because of the complex and dynamic nature of the physiological environment. Here, a strategy for directing in situ self-assembly of small molecules into fluorescent nano-aggregates in living mice is demonstrated. The nano-aggregates can be used for imaging caspase-3/7 activity in human tumour xenograft mouse models.
Studies of the Earth's atmosphere have shown that more than 90% of xenon is depleted — the so-called missing Xe paradox. Now a theoretical study shows that Xe and Fe/Ni can form inter-metallic compounds of XeFe3 and XeNi3 under conditions found in the Earth's inner core, and could provide a solution to the puzzle.
