Sodium bisulfite promotes both the deformylative deamination of 5-formylcytosine (5fC) and the decarboxylative deamination of 5-carboxylcytosine (5caC; see picture). By coupling this bisulfite chemistry with selective oxidations of individual DNA bases, new methods allow, for the first time, the sequencing of 5-hydroxymethylcytosine (5hmC) with single-base-pair resolution.

Shape matters: Changes, which are brought about by irradiation, to the properties of a medium have been of immense interest not only in terms of basic science, but also for applications such as data storage media and molecular devices. In the light of a recent publication reporting a photodriven liquid to liquid crystalline transformation (see figure), an overview of similar transitions is presented.

Seeking ideality: Intensive efforts have been invested into the discovery and/or engineering of a range of catalysts, ideally meeting the criteria shown in the picture, for the oxidative CH bond activation of linear alkanes. The comparison between chemical and enzymatic catalysts for alkane oxyfunctionalization is an extremely useful strategy to gain insights into the fundamental mechanisms of this chemistry.

Well red: Modern red fluorescent proteins (RFPs) provide new possibilities to study biological processes at the levels from single molecules to whole organisms (see scheme). Conventional and far-red RFPs, RFPs with a large Stokes shift, fluorescent timers, irreversibly photoactivatable, and reversibly photoswitchable RFPs are discussed in relationship to advanced imaging approaches.

Pencil it in: Mechanical abrasion of compressed single-walled carbon nanotubes (SWCNTs) on the surface of paper produces sensors capable of detecting NH₃ gas at sub-ppm concentrations. This method of fabrication is simple, inexpensive, and entirely solvent-free, and avoids difficulties arising from the inherent instability of many SWCNT dispersions.

A polymersome-stabilized Pickering emulsion was prepared and applied in a biphasic enzymatic reaction. This type of Pickering emulsion was stabilized by fully packed crosslinked polymersomes at the water/oil interface. CalB, as a model enzyme (red ribbon structure), was loaded either in the water phase or in the lumen of the polymersomes of the Pickering emulsion (see picture), which highly enhanced its catalytic performance and recyclability.

PIC-ing a winner: siRNA encapsulated by a phenylboronate-functionalized polyion complex (PIC) micelle shows binding between the phenylboronate and the 3′ ribose of the siRNA (see scheme), stabilizing the complex under conditions equivalent to the extracellular environment. This complex is disrupted in response to addition of ATP, at a concentration comparable to that inside cells.

Narrow ¹H NMR linewidths can be obtained for fully protonated protein samples in the solid state by using ultrafast magic-angle spinning (60 kHz). Medium-size microcrystalline and noncrystalline proteins can be analyzed without any need for deuteration of the protein sample. This approach provides assignments of the backbone ¹H, ¹⁵N, ¹³C^α, and ¹³CO resonances and yields information about ¹H–¹H proximities.

Perfect texture: The roles of surface nanotexturing, TiO₂ passivation, and a ruthenium cocatalyst on the photoelectrochemical evolution of hydrogen by using p-InP photocathodes are investigated. Higher current densities and more favorable onset potentials are observed after surface nanotexturing. NHE=normal hydrogen electrode.

Tweezing out the answer: A microfluidic device combining droplets (less than 100 nL) and magnetic particles (see scheme) was implemented for fast heterogeneous multiplexed assays. Magnetic tweezers can perform the manipulations required in an immunoassay (capture, extraction, mixing, and rinsing). This method was applied to the diagnosis of congenital hypothyroidism with 14 pM sensitivity.

Off the axis: A new lead-free bismuth based perovskite has been formed at ambient pressure in the polar Pmc2₁ structure. Measurements give evidence for ferroelectricity and piezoelectricity. The material is significant due to a rotation of the polarization direction off the [111]_p axis, making it important to the design of materials with a morphotropic phase boundary.

Try to make it ordered! Micrometer-sized PbS–organic mesocrystals show a long-range order of nanoparticles within an fcc superlattice combined with preferred orientational ordering of truncated octahedrally shaped PbS cores (see picture). The concept of formation and structuring of mesocrystalline materials is perfectly illustrated this system.

A chameleon under pressure: The observed piezochromic behavior of the title compound (BP2VA) was found to depend on its molecular aggregation state and specifically on the strength of the π–π interaction between the anthracene rings of adjacent molecules. When BP2VA is ground or placed under pressure, its molecular aggregation state changes, and a red shift in the fluorescence emission from green via orange to red occurs (see picture).

Ion conductor: A series of Sn_1–xA_xP₂O₇ (A^V=V, Nb, Ta, and Sb) compounds was synthesized, among which Sn_0.92Sb_0.08P₂O₇ (see picture) showed the highest hydroxide ion conductivity in the temperature range of 50–200 °C (0.08 S cm⁻¹ at 100 °C and 0.05 S cm⁻¹ at 200 °C). This high conductivity was also confirmed under fuel-cell-operating conditions.

Dense metastable phases obtained under “hard” high-pressure conditions may contain instabilities such as unusual oxidation states or coordination environments that may be partially relieved by “soft” low-temperature chemistry. The synthesis of SrCrO_2.8 (see picture, left) and SrCrO_2.75 (right) phases from the high-pressure perovskite SrCrO₃ leads to a relaxation of the coordination around Cr⁴⁺ from octahedral to tetrahedral.

Turn it on! β-MAP is a sensitive FRET probe with specificity for monitoring the enzyme β-secretase (BACE), which is associated with Alzheimer's disease. After hydrolysis by the enzyme BACE, the probe fluoresces and thus allows real-time spatial and temporal assessment of enzymatic activity in living cells. β-MAP was used to confirm the cellular efficacy of a reported inhibitor without the need for mutated cell lines or antibodies.

Capture and seal off all exits! Biomacromolecules are routinely microcapsulated in poly(lactic-co-glycolic acid) (PLGA) in multiple complex steps that are deleterious to the biomacromolecule. In contrast, PLGA encapsulation based on self-healing (see picture) shows high efficiency without protein damage and enables the stabilization and slow release of proteins.

Coming to light: The title reaction simply requires an aqueous alkaline solution of Selectfluor and light. The method is inexpensive and effective for a wide range of neutral and electron-poor 2-aryloxy and 2-aryl acetic acids to provide fluoromethyl ethers (see scheme) and benzyl fluorides, respectively. The mechanism most likely proceeds through an initial aryl excitation with a subsequent single-electron transfer.

Remote control: The title reaction for β–ζ arylation of α-amino esters with aryl bromides is described. This reaction, which occurs selectively at the terminal position of linear alkyl chains, gives rise to synthetically useful (hetero)arylalanines and homologues after debenzylation (see scheme).

Getting some closure: Mechanistic studies supported the participation of an oxanickelacycle complex in the hydroacylation step of the title reaction, which proceeds without decarbonylation even in the absence of well-known chelation assistance by heteroatoms.

Easy to N-cycle: The efficient synthesis of azepine derivatives was achieved by Rh-catalyzed tandem 2,3-rearrangement involving the heterocyclization of N-allenylnitrone intermediates (see scheme; cod=1,5-cyclooctadiene, tppms=sodium diphenylphosphinobenzene-3-sulfonate).

Skeletons in the closet: Four new compounds have been isolated from the title mushroom. The compounds display a new steroid skeleton (e.g., 1) not previously reported for steroids. Preliminary bioactivity tests show that compound 1 can protect neuronal cells by attenuating the endoplasmic reticulum stress, and has weak anti-methicillin-resistant Staphylococcus aureus activity.

Hot couple: Propargyl azides were coupled with carboxylic acids by an iron-catalyzed dehydrogenative CO bond formation (see scheme). This method enables propargylic CH functionalization under mild reaction conditions and also may involve the application of the azido moiety as an assisting group in CH activation.

Piña colato? In the presence of a chiral Cu^I/bisphosphine complex and B₂(pin)₂, enone diones undergo diastereo- and enantioselective desymmetrization to deliver highly functionalized bicyclic products. The products can be used as substrates in additional transformations. pin=pinacolato, Cy=cyclohexyl.

A tale of two carbenes: Reaction of :C[N(2,6-iPr₂C₆H₃)CH]₂ (IPr) with Mn₃(mes)₆ (mes=2,4,6-trimethylphenyl) yielded the trigonal planar complex [Mn(IPr)(mes)₂]. Reduction of this species with potassium/graphite in THF afforded the polymeric dicarbene-bridged species K[{:C[N(2,6-iPr₂C₆H₃)]₂(CH)C}₂Mn(mes)(thf)]⋅THF (see picture). The anionic moiety in this complex is the first reported example of a transition metal complex containing an N-heterocyclic dicarbene ligand. Gray C, blue N, red Mn.

Totally OXOme! Monomeric oxophosphonium ions have been prepared from N-heterocyclic phosphenium ions and triethylamine or pyridine N-oxides (see picture; Dipp=2,6-diisopropylphenyl). Their structures were confirmed by single-crystal X-ray crystallography.

Expect the unexpected: The reactions of a series of imidazolium pyridinium salts with [{IrCp*Cl₂}₂] and [{RhCp*Cl₂}₂] afford a series of complexes. Together with the expected bis(NHC) complexes, some species resulting from CC coupling between the pyridylidene and Cp* ligands were observed (see figure; Cp*=pentamethylcyclopentadienyl).

False identity: The synthesis of a natural product described by Faulkner and co-workers two decades ago has revealed the need for the revision of some stereochemical assignments. The key steps in this flexible route, which could provide access to stereodefined analogues for biological evaluation, included a Julia coupling, a Suzuki–Miyaura reaction, and Wittig olefination (see scheme; MOM, PMB, and TBS are protecting groups).

Shine a light: A fluorescent light-induced synthetic method for the title compounds has been developed and the chemoselective nature of the reaction is highlighted by the observation of the cis/trans isomers of various N-unsubstituted imines. The synthetic utility of this method is demonstrated by the one-pot imine formation/asymmetric allylation sequence of benzyl azide catalyzed by 1. (Ipc=isopinocampheyl).

Sulfur tyranny: Thiiranes, instead of oxiranes, can be obtained in a highly stereoselective manner through the cycloaddition reaction of N-acyl oxazolidine tethered diazo thione compounds with aldehydes catalyzed by Rh^II. Thus, this reaction provides versatile adducts S functionalized at both the α and β position, with concomitant generation of two contiguous stereocenters.

Silver bullet: A methodology for stereoselective synthesis of polysubstituted tetrahydronaphthols catalyzed by [Ag⁺]/NPO has been developed. The reactions proceeded through an unprecedented [4+2] cyclization of 2-(2-formylphenyl)ethanone and an alkene, in both inter- and intramolecular fashion. NPO=pyridine N-oxide.

Crossed products: Ortho-substituted benzaldehydes react with other aromatic aldehydes in a highly selective, atom-economical Tishchenko disproportionation (see scheme) in the presence of a readily prepared, inexpensive thiolate-based catalyst. The methodology is of exceptionally wide scope and exhibits a high functional-group tolerance.

Porphyrin without N: Bilin analogues and related aromatic dicarbaporphyrinoids have been prepared from bis(3-indenyl)methane. Even though all four pyrrole rings from the porphyrin macrocycle have been replaced by two furan and two indene subunits, the system retains porphyrin-like UV/Vis spectra and highly diatropic characteristics.

Branching out: The rhodium-catalyzed enantioselective hydroamination of monosubstituted allenes with anilines permits the atom-economic synthesis of valuable branched allylic amines. In contrast to previous linear selective allene hydroaminations, a Rh^I/Josiphos catalyst system (see scheme; cod=1,5-cyclooctadiene, DCE=1,2-dichloroethane) allows branched allylic amines to be obtained with perfect regioselectivity, high yield, and good enantioselectivity.

Closing the loop: Photoisomerization of 1,2-dihydro-1,2-azaborine in neon, argon, or xenon at 4 K with UV light (253.7 nm) as part of a matrix isolation study led to the Dewar form as the only photoproduct, in agreement with the vibrational spectra computed for possible isomers of 1,2-dihydro-1,2-azaborine.

Looking in the right (NMR) ballpark: The ¹³C shifts of carbon atoms σ-bonded to uranium(VI) centers, and in particular the ¹H shifts of U^VI bound hydride ligands, are predicted to be at unprecedentedly high frequencies (see picture), as a result of unexpectedly large spin-orbit effects. Based on relativistic quantum-chemical calculations, the right spectral ranges are suggested, which may allow identification of such compounds.

From termite soldier's secretions: The enantioselective total synthesis of the diterpene (+)-cubitene is described. The route is characterized by the cyclization of a carvone-derived C₂₀ allylphosphate with SmI₂, followed by fragmentation to the twelve-membered ring. As a result, perfect stereocontrol of the isopropenyl-substituted positions is achieved.

Tout au contraire: Both tautomeric forms of a methanetrisamidine were structurally characterized for the first time by X-ray diffraction and by ab initio calculations (see structures; gray C, red H, blue N). Their reactivity as proton acceptors and multianionic ligands was demonstrated.

By simply counting individual molecules in STM images after defined heating steps, the kinetic parameters and the activation energy of a complex surface reaction can be determined quantitatively. This procedure was demonstrated for the metalation of 2H-tetraphenylporphyrin (2HTPP) with substrate atoms on a Cu(111) surface.