Reactivity of a Hexaaryldiboron(6) Dianion as Boryl Radical Anions.

Our study unveils a novel approach to accessing boryl radicals through the spontaneous homolytic cleavage of B-B bonds. We synthesized a hexaaryl-substituted diboron(6) dianion, , via the reductive B-B coupling of 9-borafluorene. Intriguingly, compound exhibits the ability to undergo homolytic B-B bond cleavage, leading to the formation of boryl radical anions, as confirmed by EPR studies, in the presence of the 2.

DNA from herbs can be obtained from air and authenticated by polymerase chain reaction.

DNA barcoding of herbs allows accurate species authentication. However, the DNA of herbs are often not easily PCR amplified due to co-extraction of inhibitors. Methods have been developed to improve DNA extraction to reduce contaminants.

Discovery of a heat-generated compound DHD derived from water extract with inhibitory effects on colon cancer cells viability and migration.

The plant Juss. (PV) has long been used as a medicinal herb for treating intestinal disorders. Pharmacological activities such as anti-oxidation, anti-inflammation, and anti-cancer effects of compounds isolated from PV have been reported, but these bioactive compounds were not derived from PV water extract (PVW).

Bioassay guided isolation of caffeoylquinic acids from the leaves of Ilex pubescens Hook. et Arn. and investigation of their anti-influenza mechanism.

Ethnopharmacological Relevance: Ilex pubescens Hook. et Arn. (Maodongqing, MDQ) is a common herbal tea ingredient in Southern China for heat clearance and anti-inflammation.

Solution Nuclear Magnetic Resonance Structures of ATTTT and ATTTC Pentanucleotide Repeats Associated with SCA37 and FAMEs.

Expansions of ATTTT and ATTTC pentanucleotide repeats in the human genome are recently found to be associated with at least seven neurodegenerative diseases, including spinocerebellar ataxia type 37 (SCA37) and familial adult myoclonic epilepsy (FAME) types 1, 2, 3, 4, 6, and 7. The formation of non-B DNA structures during some biological processes is thought as a causative factor for repeat expansions. Yet, the structural basis for these pyrimidine-rich ATTTT and ATTTC repeat expansions remains elusive.

Robust Radical Cations of Hexabenzoperylene Exhibiting High Conductivity and Enabling an Organic Nonvolatile Optoelectronic Memory.

Herein, we report robust π-conjugated radical cations resulting from the oxidation of hexabenzoperylene (HBP) derivatives, HBP-B and HBP-H, which have butyl and hexyl groups, respectively, attached to the same twisted double helicene π-backbone. The radical cation of HBP-B was successfully crystallized in the form of hexafluorophosphate, which exhibited conductivity as high as 1.32 ± 0.

Structure and Reactivity of One- and Two-Electron Oxidized Manganese(V) Nitrido Complexes Bearing a Bulky Corrole Ligand.

As a strategy to design stable but highly reactive metal nitrido species, we have synthesized a manganese(V) nitrido complex bearing a bulky corrole ligand, [Mn(N)(TTPPC)] (, TTPPC is the trianion of 5,10,15-Tris(2,4,6-triphenylphenyl)corrole). Complex is readily oxidized by 1 equiv of CpFe to give the neutral complex , which can be further oxidized by 1 equiv of [(-Br-CH)N][B(CF)] to afford the cationic complex . All three complexes are stable in the solid state and in CHCl solution, and their molecular structures have been determined by X-ray crystallography.

Multi-methodological approach for the Quality assessment of Senecionis scandentis Herba (Qianliguang) in the herbal market.

We set forth to assess the quality of an herbal medicine sold in Hong Kong called Qianliguang by employing a multi-methodological approach. The quality is set by its identity, chemical composition, and bioactivities, among others. Qianliguang (Senecionis scandentis Herba, Senecio scandens Buch.

Anti-influenza mechanism of phenolic phytochemicals from Canarium album (Lour.) DC. leaf extract.

Ethnopharmacological Relevance: Canarium album (Lour.) DC. belongs to the Burseraceae family.

A purine and a backbone discontinuous site alter the structure and thermal stability of DNA minidumbbells containing two pentaloops.

Minidumbbell (MDB) is a noncanonical DNA structure found to form in several pyrimidine-rich short tandem repeats associated with neurodegenerative diseases. The most recently reported MDB contains two pentaloops formed by ATTCT repeats. Here, we studied the effects of a purine residue and a backbone discontinuous site on the structure and thermal stability of MDBs containing two pentaloops.

Structure and Reactivity of a Manganese(VI) Nitrido Complex Bearing a Tetraamido Macrocyclic Ligand.

Manganese complexes in +6 oxidation state are rare. Although a number of Mn(VI) nitrido complexes have been generated in solution via one-electron oxidation of the corresponding Mn(V) nitrido species, they are too unstable to isolate. Herein we report the isolation and the X-ray structure of a Mn(VI) nitrido complex, [Mn(N)(TAML)] (), which was obtained by one-electron oxidation of [Mn(N)(TAML)] ().

Effects of Adenine Methylation on the Structure and Thermodynamic Stability of a DNA Minidumbbell.

DNA methylation is a prevalent regulatory modification in prokaryotes and eukaryotes. -methyladenine (mA) and -methyladenine (mA) have been found to be capable of altering DNA structures via disturbing Watson-Crick base pairing. However, little has been known about their influences on non-B DNA structures, which are associated with genetic instabilities.

Charging a Negatively Curved Nanographene and Its Covalent Network.

This study explores a bottom-up approach toward negatively curved carbon allotropes from octabenzo[8]circulene, a negatively curved nanographene. Stepwise chemical reduction reactions of octabenzo[8]circulene with alkali metals lead to a unique highly reduced hydrocarbon pentaanion, which is revealed by X-ray crystallography suggesting a local view for the reduction and alkali metal intercalation processes of negatively curved carbon allotropes. Polymerization of the tetrabromo derivative of octabenzo[8]circulene by the nickel-mediated Yamamoto coupling reaction results in a new type of porous carbon-rich material, which consists of a covalent network of negatively curved nanographenes.

5-Methylcytosine Substantially Enhances the Thermal Stability of DNA Minidumbbells.

Minidumbbell (MDB) is a recently identified non-B DNA structure that has been proposed to associate with genetic instabilities. It also serves as a functional structural motif in DNA nanotechnology. DNA molecular switches constructed using MDBs show instant and complete structural conversions with easy manipulations.

Rational design of a reversible Mg/EDTA-controlled molecular switch based on a DNA minidumbbell.

Here we report that incorporation of an abasic site to DNA minidumbbells formed by natural sequences can lead to significant enhancements in their thermodynamic stability. Based on these stable minidumbbells, the first metal ion-controlled molecular switch which can regulate instant and reversible DNA duplex formation and dissociation has been constructed.

High-Resolution Structures of DNA Minidumbbells Comprising Type II Tetraloops with a Purine Minor Groove Residue.

Minidumbbell (MDB) is a newly discovered DNA structure formed by native sequences, which serves as a possible structural intermediate causing repeat expansion mutations in the genome and also a functional structural motif in constructing DNA-based molecular switches. Until now, all the reported MDBs containing two adjacent type II tetraloops were formed by pyrimidine-rich sequences 5'-YYYR YYYR-3' (Y and R represent pyrimidine and purine, respectively), wherein the second and sixth residues folded into the minor groove and interacted with each other. In this study, we have conducted a high-resolution nuclear magnetic resonance (NMR) spectroscopic investigation on alternative MDB-forming sequences and discovered that an MDB could also be formed stably with a purine in the minor groove, which has never been observed in any previously reported DNA type II tetraloops.

Core-dependent properties of copper nanoclusters: valence-pure nanoclusters as NIR TADF emitters and mixed-valence ones as semiconductors.

We report herein that copper alkynyl nanoclusters show metal-core dependent properties a charge-transfer mechanism, which enables new understanding of their structure-property relationship. Initially, nanoclusters and bearing respective Cu(i) () and Cu(i) () cores were prepared and revealed to display near-infrared (NIR) photoluminescence mainly from the mixed alkynyl → Cu(i) ligand-to-metal charge transfer (LMCT) and cluster-centered transition, and they further exhibit thermally activated delayed fluorescence (TADF). Subsequently, a vanadate-induced oxidative approach to generate a nucleating Cu(ii) cation led to assembly of and featuring respective [Cu(ii)O]@Cu(i) () and {[Cu(ii)O]·[VO]}@Cu(i) () cores.

Generation and Reactivity of a One-Electron-Oxidized Manganese(V) Imido Complex with a Tetraamido Macrocyclic Ligand.

The synthesis and X-ray structure of a new manganese(V) mesitylimido complex with a tetraamido macrocyclic ligand (TAML), [Mn (TAML)(N-Mes)] (1), are reported. Compound 1 is oxidized by [(p-BrC H ) N] [SbCl ] and the resulting Mn species readily undergoes H-atom transfer and nitrene transfer reactions.

Ligand-Free Iron-Catalyzed Carbon (sp)-Carbon (sp) Oxidative Homo-Coupling of Alkenyllithiums.

A new strategy was developed for the efficient synthesis of di-, tetra-, and hexa-substituted 1,3-butadienes. This one-pot procedure involves lithium-iodine exchange to generate the corresponding vinyllithium intermediates. A subsequent iron-catalyzed ligand-free oxidative homo-coupling eventually led to the formation of 1,3-butadienes in acceptable to excellent isolated yields.

A Nitrido-bridged Heterometallic Ruthenium(IV)/Iron(IV) Phthalocyanine Complex Supported by A Tripodal Oxygen Ligand, [Co(η-CH){P(O)(OEt)}]: Synthesis, Structure, and Its Oxidation to Give Phthalocyanine Cation Radical and Hydroxyphthalocyanine Complexes.

Dinuclear iron nitrido phthalocyanine complexes are of interest owing to their applications in catalytic oxidation of hydrocarbons. While nitrido-bridged diiron phthalocyanine complexes are well documented, the oxidation chemistry of heterodinuclear iron(IV) phthalocyanine nitrides has not been well explored. In this paper we report on the synthesis of a heterometallic Fe/Ru phthalocyanine nitride and its oxidation to yield phthalocyanine cation radical and hydroxyphthalocyanine complexes.

Arylruthenium(III) Porphyrin-Catalyzed C-H Oxidation and Epoxidation at Room Temperature and [Ru(Por)(O)(Ph)] Intermediate by Spectroscopic Analysis and Density Functional Theory Calculations.

The development of highly active and selective metal catalysts for efficient oxidation of hydrocarbons and identification of the reactive intermediates in the oxidation catalysis are long-standing challenges. In the rapid hydrocarbon oxidation catalyzed by ruthenium(IV) and -(III) porphyrins, the putative Ru(V)-oxo intermediates remain elusive. Herein we report that arylruthenium(III) porphyrins are highly active catalysts for hydrocarbon oxidation.

Borylene Insertion into Cage B-H Bond: A Route to Electron-Precise B-B Single Bond.

A new strategy to construct electron-precise B-B single bond via direct borylene insertion into B-H bond is described. Reduction of bromoborylene stabilized by carborane-fused silylenes with 2 equiv of sodium gives a new compound with a B-B single bond. Both experimental and density functional theory results suggest that such an electron-precise B-B single bond is formed via in situ generated borylene insertion into B-H bond.

cis-Dioxorhenium(V/VI) Complexes Supported by Neutral Tetradentate N Ligands. Synthesis, Characterization, and Spectroscopy.

A series of cis-dioxorhenium(V) complexes containing chiral tetradentate N ligands, including cis-[Re(O)(pyxn)] (1; pyxn = N,N'-dimethyl-N,N'-bis(2-pyridylmethyl)cyclohexane-1,2-diamine), cis-[Re(O)(6-Mepyxn)] (cis-2), cis-[Re(O)(R,R-pdp)] (3; R,R-pdp = 1,1'-bis((R,R)-2-pyridinylmethyl)-2,2'-bipyrrolidine), cis-[Re(O)(R,R-6-Mepdp)] (4), and cis-[Re(O)(bqcn)] (5; bqcn = N,N'-dimethyl-N,N'-di(quinolin-8-yl)cyclohexane-1,2-diamine), were synthesized. Their structures were established by X-ray crystallography, showing Re-O distances in the range of 1.740(3)-1.

Alkane Oxidation: Methane Monooxygenases, Related Enzymes, and Their Biomimetics.

Methane monooxygenases (MMOs) mediate the facile conversion of methane into methanol in methanotrophic bacteria with high efficiency under ambient conditions. Because the selective oxidation of methane is extremely challenging, there is considerable interest in understanding how these enzymes carry out this difficult chemistry. The impetus of these efforts is to learn from the microbes to develop a biomimetic catalyst to accomplish the same chemical transformation.

Toxicity of ZnO and TiO to Escherichia coli cells.

We performed a comprehensive investigation of the toxicity of ZnO and TiO nanoparticles using Escherichia coli as a model organism. Both materials are wide band gap n-type semiconductors and they can interact with lipopolysaccharide molecules present in the outer membrane of E. coli, as well as produce reactive oxygen species (ROS) under UV illumination.