Chemical Science

List of Papers (Total 4,436)

Inteins: Nature's Gift to Protein Chemists.

Inteins are auto-processing domains found in organisms from all domains of life. These proteins carry out a process known as protein splicing, which is a multi-step biochemical reaction comprised of both the cleavage and formation of peptide bonds. While ...

Detection of molecular binding via charge-induced mechanical response of optical fibers.

We report a charge sensitive optical detection technique for label-free study of molecular interactions. Traditional label-free optical detection techniques largely rely on the detection of the mass of a molecule, which are insensitive to small molecules. ...

Nuclear resonance vibrational spectroscopy reveals the FeS cluster composition and active site vibrational properties of an O2-tolerant NAD+-reducing [NiFe] hydrogenase.

Nuclear resonance vibrational spectroscopy is used to characterize all Fe-containing cofactors in a complex multicofactor enzyme.Hydrogenases are complex metalloenzymes that catalyze the reversible splitting of molecular hydrogen into protons and electrons ...

Elucidating Organ-Specific Metabolic Toxicity Chemistry from Electrochemiluminescent Enzyme/DNA Arrays and Bioreactor Bead-LC-MS/MS.

Human toxic responses are very often related to metabolism. Liver metabolism is traditionally studied, but other organs also convert chemicals and drugs to reactive metabolites leading to toxicity. When DNA damage is found, the effects are termed genotoxic. ...

A Far-Red Emitting Probe for Unambiguous Detection of Mobile Zinc in Acidic Vesicles and Deep Tissue.

Imaging mobile zinc in acidic environments remains challenging because most small-molecule optical probes display pH-dependent fluorescence. Here we report a reaction-based sensor that detects mobile zinc unambiguously at low pH. The sensor responds reversibly ...

Enantioselective Synthesis of D-α-Amino Amides from Aliphatic Aldehydes.

Bromonitromethane is used in a phase transfer-catalysed enantioselective aza-Henry reaction, leading to -amino amide bearing an alkyl chain.Peptides consisting of -amino amides are highly represented among both biologically active natural products and ...

Palladium-Catalyzed Cross-Coupling of α-Bromocarbonyls and Allylic Alcohols for the Synthesis of α-Aryl Dicarbonyl Compounds.

A palladium-catalyzed coupling of α-bromocarbonyl compounds and allylic alcohols has been developed for the generation of acyclic aryl-substituted dicarbonyl compounds.The palladium-catalyzed coupling of olefins and organohalides is a versatile ...

Rh-Catalyzed Decarbonylation of Conjugated Ynones via Carbon-Alkyne Bond Activation: Reaction Scope and Mechanistic Exploration via DFT Calculations.

In this full article, detailed development of a catalytic decarbonylation of conjugated monoynones to synthesize disubstituted alkynes is described. The reaction scope and limitation has been thoroughly investigated, and a broad range of functional groups ...

Tricyclic Analogues of Epidithiodioxopiperazine Alkaloids with Promising In Vitro and In Vivo Antitumor Activity.

Epipolythiodioxopiperazine (ETP) alkaloids are structurally elaborate alkaloids that show potent antitumor activity. However, their high toxicity and demonstrated interactions with various biological receptors compromises their therapeutic potential. ...

Triple Aryne-Tetrazine Reaction Enabling Rapid Access to a New Class of Polyaromatic Heterocycles.

One of the most challenging goals of modern synthetic chemistry is to develop multi-step reactions for rapid and efficient access to complex molecules. We report a triple aryne–tetrazine reaction that enables rapid access to a new class of polyaromatic ...

Configurationally Stable, Enantioenriched Organometallic Nucleophiles in Stereospecific Pd-Catalyzed Cross-Coupling Reactions: An Alternative Approach to Asymmetric Synthesis.

Several research groups have recently developed methods to employ configurationally stable, enantioenriched organometallic nucleophiles in stereospecific Pd-catalyzed cross-coupling reactions.Several research groups have recently developed methods to ...

Efficient conversion of primary azides to aldehydes catalyzed by active site variants of myoglobin.

The oxidation of primary azides to aldehydes constitutes a convenient but underdeveloped transformation for which no efficient methods are available. Here, we demonstrate that engineered variants of the hemoprotein myoglobin can catalyze this transformation ...

Asymmetric addition of α-branched cyclic ketones to allenamides catalyzed by a chiral phosphoric acid.

Asymmetric addition of unactivated α-branched cyclic ketones to allenamides catalyzed by a chiral phosphoric acid catalyst, generates an all-carbon quaternary stereocenter with broad substrate scope and high enantioselectivity.We describe the ...

Re-Orienting Coupling of Organocuprates with Propargyl Electrophiles from SN2' to SN2 with Stereocontrol.

Diorganocuprate() reagents derived from lithiated heterocycles and CuCN react with enantioenriched secondary propargyl bromides to give the corresponding propargylated heterocycles. While propargyl electrophiles typically undergo S[N] 2′ displacement, ...

Indacenodibenzothiophenes: synthesis, optoelectronic properties and materials applications of molecules with strong antiaromatic character.

Indeno[1,2-b]fluorenes (IFs), while containing 4n π-electrons, are best described as two aromatic benzene rings fused to a weakly paratropic s-indacene core. In this study, we find that replacement of the outer benzene rings of an IF with benzothiophenes ...

Stepwise N-H Bond Formation From N2-Derived Iron Nitride, Imide and Amide Intermediates to Ammonia.

Reduction of N[2] to ammonia in nature and in electrocatalysis takes place through 1-proton/1-electron steps, motivating efforts to experimentally study the steps during proton/electron transfer to well-characterized N[2] -derived species with bridging ...

Photoacid Behaviour in a Fluorinated Green Fluorescent Protein Chromophore: Ultrafast Formation of Anion and Zwitterion States.†.

The photophysics of the chromophore of the green fluorescent protein in Aequorea victoria (avGFP) are dominated by an excited state proton transfer reaction. In contrast the photophysics of the same chromophore in solution are dominated by radiationless ...

New Insights into the Biosynthesis of Fosfazinomycin.

The biosynthetic origin of a unique hydrazide moiety in the phosphonate natural product fosfazinomycin is unknown. This study presents the activities of five proteins encoded in its gene cluster. The flavin-dependent oxygenase FzmM catalyses the oxidation ...

Optical control of neuronal activity using a light-operated GIRK channel opener (LOGO).

G-protein coupled inwardly rectifying potassium (GIRK) channels are expressed throughout the human body and are an integral part of inhibitory signal transduction pathways. Upon binding of G[βγ] subunits released from G-protein coupled ...

Intramolecular 1,5-C(sp3)-H Radical Amination via Co(II)-Based Metalloradical Catalysis for Five-Membered Cyclic Sulfamides.

Co()-based metalloradical catalysis (MRC) proves effective for intramolecular 1,5-C–H amination of sulfamoyl azides under neutral and nonoxidative conditions, providing a straightforward approach to access strained 5-membered cyclic sulfamides ...

Prostate-specific membrane antigen targeted gold nanoparticles for prostate cancer radiotherapy: does size matter for targeted particles?

Since the introduction of PSA testing, significantly more men have been diagnosed and treated for prostate cancer. Localized prostate cancer typically is treated with prostatectomy, however there is still a high risk of recurrence after surgery, and adjuvant ...

Seconds-resolved pharmacokinetic measurements of the chemotherapeutic irinotecan in situ in the living body.

The ability to measure drugs in the body rapidly and in real time would advance both our understanding of pharmacokinetics and our ability to optimally dose and deliver pharmacological therapies. To this end, we are developing electrochemical aptamer-based ...

Achieving high performance poly(vinylidene fluoride) dielectric composites via in situ polymerization of polypyrrole nanoparticles on hydroxylated BaTiO3 particles.

Polymer dielectric composites have widespread applications in many fields ranging from energy storage, microelectronic devices, and sensors to power driven systems, etc. and attract much attention of researchers. However, it is still challenging to prepare ...

Hierarchically porous carbons as supports for fuel cell electrocatalysts with atomically dispersed Fe-N x moieties.

The development of high-performance non-platinum group metal (non-PGM) catalysts for the oxygen reduction reaction (ORR) is still of significance in promoting the commercialization of proton exchange membrane fuel cells (PEMFCs). In this work, a “hierarchically ...