Halogen Complexes of Anionic N-Heterocyclic Carbenes.
Abstract The lithium complexes [WCA-NHC)Li(toluene)] of anionic N-heterocyclic carbenes with a weakly coordination anionic borate moiety (WCA-NHC) reacted with iodine, bromine or CCl 4 to afford the zwitterionic 2-halogenoimidazolium borates (WCA-NHC)X (X = I, Br, Cl; WCA = B(C 6 F 5 ) 3 , B{3,5-C 6 H 3 (CF 3 ) 2 } 3 ; NHC = IDipp = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene or NHC = IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene). The iodine derivative (WCA-IDipp)I (WCA = B(C 6 F 5 ) 3 ) formed several complexes of the type (WCA-IDipp)I·L (L = C 6 H 5 Cl, C 6 H 5 Me, CH 3 CN, THF, ONMe 3...
Source: Chemistry - October 23, 2020 Category: Chemistry Authors: Frosch J, Koneczny M, Bannenberg T, Tamm M Tags: Chemistry Source Type: research

Crystal structure of urotropine under high pressure and non-hydrostatic stress-induced phase transitions in cage compounds.
Abstract High-pressure behavior of hexamethylenetetramine (urotropine) was studied in situ using angle-dispersive single-crystal synchrotron X-ray diffraction (XRD) and Fourier transform infrared absorption (FTIR) spectroscopy. Experiments were conducted in various pressure transmitting media to study the effect of deviatoric stress on phase transformations. Up to 4 GPa significant damping of molecular librations and atomic thermal motion was observed. A first-order phase transition to a tetragonal structure was observed with an onset at ~12.5 GPa which is characterized by sluggish kinetics and considerable hyster...
Source: Chemistry - October 23, 2020 Category: Chemistry Authors: Guńka PA, Olejniczak A, Fanetti S, Bini R, Collings IE, Svitlyk V, Dziubek KF Tags: Chemistry Source Type: research

Photoactivatable Fluorophore for STED Microscopy and Bioconjugation Technique for Hydrophobic Labels.
Abstract The use of photoactivatable dyes in STED microscopy has so far been limited by two-photon activation through the STED beam and by the fact that photoactivatable dyes are poorly solvable in water. Here we report ONB-2SiR, a fluorophore that can be both photoactivated in the UV and specifically de-excited by STED at 775 nm. Likewise, we introduce a conjugation and purification protocol to effectively label primary and secondary antibodies with moderately water-soluble dyes. Greatly reducing dye aggregation, our technique provides a defined and tunable degree of labeling, and improves the imaging performance...
Source: Chemistry - October 23, 2020 Category: Chemistry Authors: Hell SW, Weber M, Khan TA, Patalag LJ, Bossi M, Leutenegger M, Belov VN Tags: Chemistry Source Type: research

First Tribo-excited Chemical Reaction of a Stacked Lanthanide Coordination Polymer with in Situ Reaction Monitor.
Abstract A tribo-excited chemical reaction using a stacked lanthanide coordination polymer is demonstrated for the first time. The polymer is composed of a Eu III ion, hexafluoroacetylacetonato ligands, and an anthracene-based phosphine oxide bridge. The tightly stacked structure with hydrogen bonding was characterized by X-ray crystal structure analysis. The mechanical stimulus leads to tribo-excited oxidation in the Eu III coordination polymer. Electron ionization mass spectroscopy and photo-spectroscopic analysis reveal that the chemical product afforded by tribo-oxidation is different from that obtained by pho...
Source: Chemistry - October 22, 2020 Category: Chemistry Authors: Kitagawa Y, Naito A, Fushimi K, Hasegawa Y Tags: Chemistry Source Type: research

Cyclodextrin-Based [c2]Daisy Chain Rotaxane Insulating Two Diarylacetylene Cores.
Abstract A [c2]daisy chain rotaxane with two diarylacetylene cores was efficiently synthesized in 53% yield by capping a C2-symmetric pseudo[2]rotaxane composed of two diarylacetylene-substituted permethylated α-cyclodextrins (PM α-CDs) with aniline stoppers. The maximum absorption wavelength of the [c2]daisy chain rotaxane remained almost unchanged in various solvents, unlike that of the stoppered monomer, indicating that the two independent diarylacetylene cores were insulated from the external environment by the PM α-CDs. Furthermore, the [c2]daisy chain rotaxane exhibited fluorescence emissio...
Source: Chemistry - October 22, 2020 Category: Chemistry Authors: Tsuda S, Komai Y, Fujiwara SI, Nishiyama Y Tags: Chemistry Source Type: research

A straightforward synthesis of polyketides via ester dienolate Matteson homologation.
Abstract Application of ester dienolates as nucleophiles in Matteson homologations allows the stereoselective synthesis of highly substituted α,β-unsaturated δ-hydroxy carboxyl acids, structural motifs widespread found in polyketide natural products. The protocol is rather flexible and permits the introduction of substituents and functionalities also at those positions which are not accessible by the commonly used aldol reaction. Therefore, this ester dienolate Matteson approach is an intersting alternative to the "classical" polyketide syntheses. PMID: 33089903 [PubMed - as supplie...
Source: Chemistry - October 22, 2020 Category: Chemistry Authors: Andler O, Kazmaier U Tags: Chemistry Source Type: research

Aromaticity Survival in Hydrofullerenes: The Case of C66H4 with its π-Aromatic Circuits.
Aromaticity Survival in Hydrofullerenes: The Case of C66H4 with its π-Aromatic Circuits. Chemistry. 2020 Oct 22;: Authors: Chen D, Szczepanik DW, Zhu J, Muñoz-Castro A, Solà M Abstract The isolated-pentagon rule (IPR) is a determining structural feature accounting for hollow fullerene stabilization and properties related to Cn (n ≥ 60) cages. The recent characterization of an unprecedented non-IPR hydrofullerene, C2v-C66H4, bearing two heptagons with adjacent fused-pentagons motif, largely dismiss this feature. Herein, employing DFT calculations, we explore the 13C-NMR pattern and ...
Source: Chemistry - October 22, 2020 Category: Chemistry Authors: Chen D, Szczepanik DW, Zhu J, Muñoz-Castro A, Solà M Tags: Chemistry Source Type: research

Gas phase structures of potassium tetrakis(hexafluoroacetyl-ace-to-nato)-lanthanate(III) complexes [KLn(C5HF6O2)4] (Ln = La, Gd, Lu).
Abstract The molecular structures of potassium tetrakis(hexafluoro-acetylacetonato)lanthanate(III) complexes [KLn(hfa) 4 ] (Ln = La, Gd, Lu; hfa = C 5 HF 6 O 2 ,) were studied by synchronous gas-phase elec-tron diffraction / mass spectrometry (GED/MS) supported by quan-tum-che-mical (DFT/PBE0) calculations. The compounds subli-mate con-gru-ently and the vapors contain single molecular species - the hete-ro--binuclear complex [KLn(hfa) 4 ]. All molecules are of C 1 sym-me-try with the lanthanide atom in the center of a coordination poly-hedron LnO 8 , while the potassium atom is coordinated by three ligands under f...
Source: Chemistry - October 22, 2020 Category: Chemistry Authors: Mitzel NW, Girichev GV, Giricheva NI, Khochenkov AE, Sliznev V, Belova N Tags: Chemistry Source Type: research

The 2-Amino Group of 8-Aza-7-deaza-7-bromopurine-2,6-diamine and Purine-2,6-diamine as Stabilizer for the Adenine-Thymine Base Pair in Heterochiral DNA with Strands in Anomeric Configuration.
Abstract Stabilization of DNA is beneficial for many applications in the fields of DNA therapeutics, diagnostics and material science. Now, this phenomenon is studied on heterochiral DNA, an autonomous DNA recognition system with complementary strands in α-D and β-D configuration showing parallel strand orientation. 12-mer heterochiral duplexes were constructed from anomeric (α/β-D) oligonucleotide single-strands. Purine-2,6-diamine and 8-aza-7-deaza-7-bromopurine-2,6-diamine 2'-deoxyribonucleosides having the capability to form tridentate base pairs with dT were used to strengthen the stabil...
Source: Chemistry - October 22, 2020 Category: Chemistry Authors: Seela F, Chai Y, Kondhare D, Zhang A, Leonard P Tags: Chemistry Source Type: research

Similarities and differences between crystal and enzyme environmental effects on the electron density of drug molecules.
In this study, we compare the crystal interaction density and the interaction electrostatic potential for a model compound of loxistatin acid (E64c) with those inside cathepsin B, in solution and in vacuum. We apply QM/MM calculations and experimental quantum crystallography to show that the crystal interaction density is indeed very similar to the enzyme interaction density. Less than 0.1e are shifted between these two environments in total. However, this has non-negligible consequences for derived properties. PMID: 33090581 [PubMed - as supplied by publisher] (Source: Chemistry)
Source: Chemistry - October 22, 2020 Category: Chemistry Authors: Kleemiss F, Wieduwilt EK, Hupf E, Shi MW, Stewart SG, Jayatilaka D, Turner MJ, Sugimoto K, Nishibori E, Schirmeister T, Schmidt TC, Engels B, Grabowsky S Tags: Chemistry Source Type: research

Synthesis of asparagine derivatives harboring a Lewis X type DC-SIGN ligand and evaluation of their impact on immunomodulation in multiple sclerosis.
Abstract The protein myelin oligodendrocyte glycoprotein (MOG) is a key component of myelin and an autoantigen in the disease multiple sclerosis (MS). The posttranslational N-glycosylation of Asn31 of MOG seems to play a key role in modulating the immune response towards myelin. This is mediated by the interaction of Lewis type glycan structures on the N-glycan of MOG to the DC-SIGN receptor on dendritic cells (DCs). Here, we report the synthesis of an unnatural Lewis X (LeX) containing Fmoc-SPPS compatible asparagine building block, as well as asparagine building blocks containing two LeX derived oligosaccharides...
Source: Chemistry - October 22, 2020 Category: Chemistry Authors: Doelman W, Marqvorsen MHS, Chiodo F, Bruijns SCM, van der Marel GA, van Kooyk Y, van Kasteren SI, Araman C Tags: Chemistry Source Type: research

Self-assembly two-dimensional NiO/CeO2 heterostructure rich in oxygen vacancies as efficient bifunctional electrocatalyst for alkaline hydrogen evolution and oxygen evolution.
Abstract Developing high-efficiency bifunctional electrocatalysts toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline surroundings is essential and challenging for generating clean hydrogen massively. Herein, a novel self-assembly two-dimensional (2D) NiO/CeO2 heterostructure (HS) consisted of NiO and CeO2 nanocrystals has been firstly prepared via a facile two-step approach and utilized as an enhanced bifunctional electrocatalyst for HER and OER under alkaline condition. It is concluded that 2D NiO/CeO2 HS rich in oxygen vacancies demonstrates attractive electrocatalytic prope...
Source: Chemistry - October 21, 2020 Category: Chemistry Authors: Zhang Y, Ye F, Li W Tags: Chemistry Source Type: research

Strong Equatorial Crystal Field Enhances the Axial Anisotropy and Energy Barrier for Spin Reversal Process in Yb2 SMMs.
Abstract The importance of equatorial crystal fields on magnetic anisotropy of ytterbium SMMs is observed for the first time. Herein, we report three similar dinuclear ytterbium complexes of formula [Yb 2 (3-OMe-L) 2 (DMF) 2 (NO 3 ) 2 ]·DMF ( 1 ), [Yb 2 (3-H-L) 2 (DMF) 2 (NO 3 ) 2 ]·DMF·H 2 O ( 2 ) and [Yb 2 (3-NO 3 -L) 2 (DMF) 2 (NO 3 ) 2 ] ( 3 ), [where 3-X-H 2 L= N'-(2-hydroxy-3-X-benzylidene)picolinohydrazide, X = OMe( 1 ), H( 2 ) NO 2 ( 3 )]. The detailed magnetic measurements display the presence of weak antiferromagnetic interaction between the Yb centers and field induced slow relaxati...
Source: Chemistry - October 21, 2020 Category: Chemistry Authors: Konar S, Mondal A Tags: Chemistry Source Type: research

Corrigendum: Ranking Oxidant Sensitiveness: A Guide for Synthetic Utility.
PMID: 33085117 [PubMed] (Source: Chemistry)
Source: Chemistry - October 21, 2020 Category: Chemistry Authors: Dallaston MA, Bettencourt CJ, Chow S, Gebhardt J, Spangler J, Johnston MR, Wall C, Brusnahan JS, Williams CM Tags: Chemistry Source Type: research

Inverse-Electron-Demand Diels-Alder Reactions of 2-Pyrones: Bridged Lactones and Beyond.
Abstract Inverse-electron-demande Diels-Alder (IEDDA) reactions of electron-poor 2-pyrones as electrophilic dienes have been extensively studied in the past fifty years. These reactions provide and efficient access to bridged bicyclic lactones and their derivatives, such as densely functionalized 1,3-cyclohexadienes after CO 2 extrusion and polysubstituted aromatic compounds through elimination. This reaction has been used for the synthesis of many biologically active natural products and drug candidates. In this review, the developments of these IEDDA reactions including non-catalytic, Lewis acid-catalyzed and or...
Source: Chemistry - October 21, 2020 Category: Chemistry Authors: Huang G, Kouklovsky C, de la Torre A Tags: Chemistry Source Type: research

Electrochemical C-H Amidation of Heteroarenes with N-Alkyl Sulfonamides in Aqueous Medium.
Abstract The construction of C-N bonds by free radical reactions represents a powerful synthetic approach for direct C-H amidations of arenes or heteroarenes. Developing efficient and more environmentally-friendly synthetic methods for C-H amidation reactions remains highly desirable. Herein, metal-free electrochemical oxidative dehydrogenative C-H amidations of heteroarenes with N -alkylsulfonamides have been accomplished. The catalyst- and chemical oxidant-free C-H amidation features an ample scope, and employes electricity as the green and sole oxidant. A variety of heteroarenes, including indoles, pyrroles, be...
Source: Chemistry - October 21, 2020 Category: Chemistry Authors: Zhang Y, Lin Z, Ackermann L Tags: Chemistry Source Type: research

Twofold C-H Activation Enables Synthesis of a Diazacoronene-type Fluorophore with Near Infrared Emission through Isosteric Replacement.
us F Abstract The synthesis and photophysical properties of a soluble amide-embedded coronene is reported. The key step in this synthesis is the twofold C-H activation of diazaperylene by a rhodium(III)Cp* catalyst. This unprecedented structural motif shows intense fluorescence in the near infrared region with a small Stokes shift and a distinct vibronic structure, which exhibits a slight extent of negative solvatochromism. Comparison of this compound with some relevant compounds revealed the importance of the amide incorporation in the peripheral concave region including an angular position to retain high aromati...
Source: Chemistry - October 21, 2020 Category: Chemistry Authors: Greßies S, Ito M, Sakai M, Osaki H, Kim JH, Gensch T, Daniliuc C, Ando N, Yamaguchi S, Glorius F Tags: Chemistry Source Type: research

Design Platform for Sustainable Catalysis with Radicals: Electrochemical Activation of Cp2TiCl2 for Catalysis Unveiled.
l;fer L Abstract The combination of synthesis, rotating ring-disk electrode (RRDE) and cyclic voltammetry (CV) measurements, and computational investigations with the aid of DFT methods shows how a thiourea, a squaramide, and a bissulfonamide as additives affect the EqCr equilibrium of Cp2TiCl2. We have, for the first time, provided quantitative data for the EqCr equilibrium and have determined the stoichiometry of adduct formation of [Cp2Ti(III)Cl2]-, [Cp2Ti(III)Cl] and [Cp2Ti(IV)Cl2] and the additives. By studying the structures of the complexes formed by DFT methods, we have established the Gibbs energies and e...
Source: Chemistry - October 21, 2020 Category: Chemistry Authors: Gansäuer A, Hilche T, Reinsberg PH, Klare S, Liedtke T, Schäfer L Tags: Chemistry Source Type: research

CoPd Nanoalloys with MOF as Template for Both N-doped Carbon and Cobalt Precursor: Efficient and Robust Catalysts for Hydrogenation Reactions.
Abstract In this work, a series of MOF-derived CoPd nanoalloys have been prepared. The nanocatalysts exhibited excellent activities in the hydrogenation of nitroarenes and alkenes in green solvent (ethanol/water) under mild conditions (H 2 balloon, room temperature). Using ZIF-67 as template for both carbon matrix and cobalt precursor coating with a mesoporous SiO 2 layer, the catalyst CoPd/NC@SiO 2 were smoothly constructed. Catalytic results revealed the synergistic effect between Co and Pd components in the hydrogenation process due to the enhanced electron density. Mesoporous SiO 2 shell effectively prevented ...
Source: Chemistry - October 20, 2020 Category: Chemistry Authors: Zhu J, Xu D, Ding LJ, Wang P Tags: Chemistry Source Type: research

Synthesis of Morpholine-Based Analogs of (-)-Zampanolide and Their Biological Activity.
We describe the convergent synthesis of three prototypical examples of a new class of analogs of the complex, cytotoxic marine macrolide (-)-zampanolide, which incorporate an embedded N- substituted morpholine moiety in place of the natural tetrahydropyran ring. The final construction of the macrolactone core was based on a high-yielding intramolecular HWE olefination, while the hemiaminal-linked side chain was elaborated through a stereoselective, BINAL-H-mediated addition of ( Z,E )-sorbamide to a macrocyclic aldehyde precursor. The synthesis of the common functionalized morpholine building block involved two consecutive...
Source: Chemistry - October 20, 2020 Category: Chemistry Authors: Altmann KH, Bold CP, Gut M, Schürmann J, Lucena Agell D, Diaz JF, Gertsch J Tags: Chemistry Source Type: research

Towards Photochromic Azobenzene-Based Inhibitors for Tryptophan Synthase.
In conclusion, we created a promising lead compound for the combat of bacterial diseases, which targets an essential metabolic enzyme, and whose inhibition strength can be controlled with light. PMID: 33078454 [PubMed - as supplied by publisher] (Source: Chemistry)
Source: Chemistry - October 20, 2020 Category: Chemistry Authors: Simeth NA, Kinateder T, Rajendran C, Nazet J, Merkl R, Sterner R, König B, Kneuttinger AC Tags: Chemistry Source Type: research

Quantification of Non-covalent Interactions in Azide-Pnictogen, -Chalcogen, and -Halogen Contacts.
Abstract The non-covalent interaction between azide and oxygen containing moieties is investigated by a computational study based on  experimental findings. Targeted synthesis of organic compounds with close intramolecular azide-oxygen contacts yielded six new representatives, for which X-ray structures were determined. Two of those compounds were investigated with respect to their potential conformations in the gas-phase and a possible significantly short azide-oxygen contact. Furthermore, a set of 44 high-quality gas-phase computational model systems with intermolecular azide-pnictogen (N, P, As, Sb), chalc...
Source: Chemistry - October 20, 2020 Category: Chemistry Authors: Bursch M, Kunze L, Vibhute AM, Hansen A, Sureshan KM, Jones PG, Grimme S, Werz DB Tags: Chemistry Source Type: research

Dithieno[a,e]pentalenes: Highly Antiaromatic Yet Stable π-Electron Systems without Bulky Substituents.
Dithieno[a,e]pentalenes: Highly Antiaromatic Yet Stable π-Electron Systems without Bulky Substituents. Chemistry. 2020 Oct 20;: Authors: Usuba J, Hayakawa M, Yamaguchi S, Fukazawa A Abstract Dithieno[a,e]penalenes (DTPs) with various substituents were synthesized as a class of antiaromatic compounds. Annulation of thiophene rings imparts the pentalene moiety with high thermal stability even without bulky substituents, while retaining antiaromaticity. The higher magnitude of antiaromaticity in DTPs, in addition to the differences in the electronic structures of the fused aromatic rings, resulted in ...
Source: Chemistry - October 20, 2020 Category: Chemistry Authors: Usuba J, Hayakawa M, Yamaguchi S, Fukazawa A Tags: Chemistry Source Type: research

Gold(I) Complexation of the Phosphanoxy-Substituted Phosphaalkenes for the Activation-Free LAuCl Catalysis.
Abstract The phosphanoxy-substituted phosphaalkene bearing the P=C-O-P skeleton can be prepared from diphosphene Mes*P=PMes* (Mes* = 2,4,6- t Bu 3 C 6 H 2 ), and the use for catalysis is of interest. In this paper, complexation of the phosphanoxy-substituted phosphaalkenes with gold are investigated, and the catalytic activity of the mono- and bis(chlorogold) complexes are subsequently evaluated. Reaction of the P=C-O-P compound with (tht)AuCl (tht = tetrahydrothiophene) showed dominant coordination on the sp 3 phosphorus, and complete coordination on the sp 2 phosphorus required removal of tetrahydrothiophene. At...
Source: Chemistry - October 20, 2020 Category: Chemistry Authors: Kato M, Ueta Y, Ito S Tags: Chemistry Source Type: research

A Selective Sulfide Oxidation catalyzed by Heterogeneous Artificial Enzymes Iron@NikA.
Abstract Performing a heterogeneous catalysis with proteins is still a challenge. Here, we demonstrate the importance of cross-linked crystals for sulfoxide oxidation by an artificial enzyme. The biohybrid consists of the insertion of an iron complex into a NikA protein crystal. The heterogeneous catalysts displays a better efficiency-with higher reaction kinetics, a better stability and expand the substrate scope compared to its solution counterpart. Designing crystalline artificial enzymes represents a good alternative to soluble or supported enzymes for the future of synthetic biology. PMID: 33079395 [PubM...
Source: Chemistry - October 20, 2020 Category: Chemistry Authors: Menage S, Lopez S, Marchi-Delapierre C, Cavazza C Tags: Chemistry Source Type: research

Circularly Polarized Luminescence of A Stereogenic Curved Paraphenylene Anchoring A Chiral Binaphthyl in Solution and Solid State.
Abstract A curved stereogenic [6]paraphenylene ([6]PP), anchoring a chiral binaphthyl scaffold at 7,7'-positions, was prepared and investigated for its properties as a solid-state circularly polarized luminescence (CPL) dye. X-ray analysis revealed a helically twisted structure of PP units induced by axial chirality of binaphthyl framework. The curved [6]PP exhibits fluorescence in powder and polymethyl methacrylate (PMMA) film as well as solution. A significant increase in quantum yield was observed for a non-fluid PMMA film owing the suppression of the molecular motion. The g CPL values of the dye in solution an...
Source: Chemistry - October 20, 2020 Category: Chemistry Authors: Sato K, Hasegawa M, Nojima Y, Hara N, Nishiuchi T, Imai Y, Mazaki Y Tags: Chemistry Source Type: research

Enhancing magnetic communication between metal centres: the role of s-tetrazine based radicals as ligands.
Abstract Although 1,2,4,5-tetrazines or s -tetrazines have been known in the literature for more than a century, their coordination chemistry has become increasingly popular in recent years due to their unique redox activity, multiple binding sites and their various applications. The electron-poor character of the ring and stabilization of the radical anion through all four nitrogen atoms in their metal complexes provide new aspects in molecular magnetism towards the synthesis of new high performing Single Molecule Magnets (SMMs). The scope of this review is to examine the role of s -tetrazine radical ligands in t...
Source: Chemistry - October 20, 2020 Category: Chemistry Authors: Murugesu M, Mavragani N, Kitos AA, Brusso JL Tags: Chemistry Source Type: research

Strain Release Chemistry of Photogenerated Small-Ring-Intermediates.
Abstract Photochemical processes such as isomerizations and cycloadditions have proven to be very useful in the construction of highly strained molecular frameworks. Photoinduced ring-strain enables subsequent exergonic reactions which do not require the input of additional chemical energy as well as a variety of attractive synthetic options leading to complex structures. This review covers the progress achieved in the application of sequences combining excitation by ultraviolet light to form strained intermediates, which are further transformed to lower energy products in strain-release reactions. As ring strain ...
Source: Chemistry - October 20, 2020 Category: Chemistry Authors: Luque A, Paternoga J, Opatz T Tags: Chemistry Source Type: research

Isolation of a 16 π-Electrons 1,4-Diphosphinine-1,4-diide with a Planar C4P2 Ring.
Isolation of a 16π-Electrons 1,4-Diphosphinine-1,4-diide with a Planar C4P2 Ring. Chemistry. 2020 Oct 20;: Authors: Ghadwal R, Rottschäfer D, Neumann B, Stammler HG, Andrada D, Sergeieva T Abstract Herein, we report the first 1,4-diphosphinine-1,4-diide compound [(ADC Ph )P] 2 ( 5-Ph ) (ADC Ph = PhC{(NDipp)C} 2 ; Dipp = 2,6-iPr 2 C 6 H 3 ) derived from an anionic dicarbene (ADC Ph ) as a red crystalline solid. Compound 5-Ph containing a 16π-electron planar fused-tricyclic ring system was obtained by the 4e reduction of [(ADC Ph )PCl 2 ] 2 ( 4-Ph ) with Mg (or KC 8 ) in a quantitative yield....
Source: Chemistry - October 20, 2020 Category: Chemistry Authors: Ghadwal R, Rottschäfer D, Neumann B, Stammler HG, Andrada D, Sergeieva T Tags: Chemistry Source Type: research

Development of ADPribosyl ubiquitin analogs to study enzymes involved in Legionella infection.
In this study we use a modular approach for the synthesis of triazole-linked Ub ADPr and analogues thereof and determine their affinity towards the hydrolase DupA, and compare its proteolysis to natively linked Ub ADPr . The inhibitory effects of modified Ub on the canonical eukaryotic E1-enzyme Uba1 are investigated and rationalized in the context of a high-resolution crystal structure reported here. Finally, we show that the synthetic Ub ADPr can be used to effectively pull-down over-expressed DupA from cell lysate. PMID: 33075184 [PubMed - as supplied by publisher] (Source: Chemistry)
Source: Chemistry - October 19, 2020 Category: Chemistry Authors: van der Heden van Noort G, Kim RQ, Misra M, Alexis G, Tomašković I, Shin D, Schindelin H, Filippov DV, Ovaa H, Dikic I Tags: Chemistry Source Type: research

Generation of oxidoreductases with dual alcohol dehydrogenase and amine dehydrogenase activity.
Abstract The l-lysine-ε-dehydrogenase (LysEDH) from Geobacillus stearothermophilus naturally catalyzes the oxidative deamination of the ε-amino group of l-lysine. We previously engineered this enzyme to create amine dehydrogenase (AmDH) variants that possess a new hydrophobic cavity in their active site such that aromatic ketones can bind and be converted into α-chiral amines with excellent enantioselectivity. We also recently observed that LysEDH was capable of reducing aromatic aldehydes into primary alcohols. Herein, we harnessed the promiscuous alcohol dehydrogenase (ADH) activity of LysE...
Source: Chemistry - October 19, 2020 Category: Chemistry Authors: Tseliou V, Schilder D, Masman MF, Knaus T, Mutti F Tags: Chemistry Source Type: research

Nest-Like Silver(I) Thiolate Clusters Templated by Hetero Anions with Tunable Colored Emission.
Abstract Four silver thiolate clusters, [H3O]·[(Ag3S3)(BF4)@Ag27( t BuS)18(hfac)6H2O]·H2O (1; hfac = hexafluoroacetylacetone), [(Ag3S3)(CF3CO2)@Ag30( t BuS)16(CF3CO2)9(CH3CN)4]·CF3CO2·4CH3CN (2), [(Ag3S3)(MoO4)@Ag30( t BuS)16(CF3CO2)9(CH3CN)4]·2CH3CN (3), and [(Ag3S3)(CrO4)@Ag30( t BuS)16(CF3CO2)9(CH3CN)4]·4CH3CN (4), were isolated, which have the similar nest-like structure assembled by a [Ag3S3]3- template together with one of BF4-, CF3CO2-, MoO42- and CrO42- anions. Interestingly, the solid-state emissions of 2-4 are dependent on the templating anions and are tunable fr...
Source: Chemistry - October 19, 2020 Category: Chemistry Authors: Xie YP, Shen YL, Jin JL, Duan GX, Yu PY, Lu X Tags: Chemistry Source Type: research

Bis(bipyridine)ruthenium(II) ferrocenyl β-diketonate complexes: exhibiting nanomolar potency against human cancer cell lines.
Bis(bipyridine)ruthenium(II) ferrocenyl β-diketonate complexes: exhibiting nanomolar potency against human cancer cell lines. Chemistry. 2020 Oct 19;: Authors: Allison M, Caramés-Méndez P, Pask CM, Phillips RM, Lord RM, McGowan PC Abstract The synthesis and characterisation of new bis(bipyridine)ruthenium(II) ferrocenyl β-diketonate complexes, [(bpy)2Ru(Fc-acac)][PF6] (bpy = 2,2'-bipyridine; Fc-acac = functionalized ferrocenyl β-diketonate ligand) are reported. Alongside clinical platinum drugs, these bimetallic ruthenium-iron complexes have been screened for their cytotox...
Source: Chemistry - October 19, 2020 Category: Chemistry Authors: Allison M, Caramés-Méndez P, Pask CM, Phillips RM, Lord RM, McGowan PC Tags: Chemistry Source Type: research

Germaborenes: Borylene Transfer Agents for the Synthesis of Iminoboranes.
Abstract Halide and phenyl substituted germaborenes were shown to react with azides at room temperature and transfer a borylene moiety to give iminoboranes. This iminoborane synthesis based on a borylene transfer route was investigated computationally in the case of the phenyl substituted germaborene. PMID: 33073886 [PubMed - as supplied by publisher] (Source: Chemistry)
Source: Chemistry - October 19, 2020 Category: Chemistry Authors: Wesemann L, Schubert H, Raiser D, Bettinger HF Tags: Chemistry Source Type: research

Structural Transformations and Spin-Crossover in [FeL2]2+  Salts (L = 4-{tertbutylsulfanyl}-2,6-di{pyrazol-1-yl}pyridine) - the Influence of Bulky Ligand Substituents.
Structural Transformations and Spin-Crossover in [FeL2]2+ Salts (L = 4-{tertbutylsulfanyl}-2,6-di{pyrazol-1-yl}pyridine) - the Influence of Bulky Ligand Substituents. Chemistry. 2020 Oct 19;: Authors: Kulmaczewski R, Bamiduro F, Shahid N, Cespedes O, Halcrow MA Abstract 4-(Tert-butylsulfanyl)-2,6-di(pyrazol-1-yl)pyridine (L) was obtained in low yield from a one-pot reaction of 2,4,6-trifluoropyridine with 2-methylpropane-2-thiolate and sodium pyrazolate in a 1:1:2 ratio. The materials [FeL2][BF4]2·solv (1[BF4]2·solv) and [FeL2][ClO4]2·solv (1[ClO4]2·solv; solv = MeNO2,...
Source: Chemistry - October 19, 2020 Category: Chemistry Authors: Kulmaczewski R, Bamiduro F, Shahid N, Cespedes O, Halcrow MA Tags: Chemistry Source Type: research

Dynamic Helicates Self-Assembly from Homo- and Heterotopic Dynamic Covalent Ligand Strands.
hn JM Abstract The understanding and the application of reversible covalent reactions and coordination chemistry together with the proper design of the molecular frameworks, allow to achieve not only well-defined output architectures but also different grades of complex behavior. In this work, the dynamic nature of the helical systems offers an additional level of complexity by combining self-sorting on two levels: 1) the build-up of the ligand strand constituents from their components through dynamic covalent chemistry; 2) the assembly of the helicates from the ligands and the metal cations through dynamic me...
Source: Chemistry - October 19, 2020 Category: Chemistry Authors: Santoro A, Holub J, Fik-Jaskółka MA, Vantomme G, Lehn JM Tags: Chemistry Source Type: research

Polyamine-functionalized 2'-amino-LNA in oligonucleotides: Facile synthesis of novel monomers and high affinity binding towards ssDNA and dsDNA.
In this study, polyamine functionalities were introduced into ONs via 2'-amino-LNA scaffolds. The resulting ONs exhibited efficient binding towards ssDNA, ssRNA and dsDNA targets, with the 2'-amino-LNA analogue carrying a tri-aminated linker showing the most pronounced duplex and triplex stabilizing effect. Molecular modelling revealed that favourable conformational and electrostatic effects led to the salt-bridge formed between positive-charged polyamine moieties and the Watson-Hoogsteen groove of the dsDNA targets, resulting in the observed triplex stabilization. All the investigated monomers conferred increased resistan...
Source: Chemistry - October 19, 2020 Category: Chemistry Authors: Danielsen MB, Christensen NJ, Jørgensen PT, Jensen KJ, Wengel J, Lou C Tags: Chemistry Source Type: research

Enantioselective aromatic amination?
ureau FW Abstract The atroposelective formation of C-N bonds has recently emerged within the field of amination reactions. On first sight, it may seem quite surprising that such an ancient class or organic coupling reactions (Gabriel, Ullmann, Goldberg, Buchwald, Hartwig and many others) has so few enantioselective solutions, and this in spite of asymmetric synthesis being now a mature concept and field. Why should enantioselective C-N bond formation be so difficult? This question and some of the first examples that promise an imminent change of paradigm are herein discussed. PMID: 33073420 [PubMed - as suppl...
Source: Chemistry - October 18, 2020 Category: Chemistry Authors: Thönnißen V, Patureau FW Tags: Chemistry Source Type: research

Recent progress of Nickel-rich layered cathode materials for lithium ion batteries.
Abstract Nickel-rich layered transition metal oxides are considered as promising cathode candidate to construct next-generation lithium ion batteries to satisfy the demands of electrical vehicles, because of the high energy density, low cost and environment friendliness. However, some problems related with rate capability, structure stability and safety still hamper the commercial application. In this review, beginning with the relations between the physicochemical properties and electrochemical performance, the behind mechanisms of the capacity/voltage fade and the unstable structure of Ni-rich cathodes are deepl...
Source: Chemistry - October 18, 2020 Category: Chemistry Authors: Ye Z, Qiu L, Yang W, Wu Z, Liu Y, Wang G, Song Y, Zhong B, Guo X Tags: Chemistry Source Type: research

Generation of α-Boryl Radicals and Their Conjugate Addition to Enones: Transition-Metal-Free Alkylation of gem-Diborylalkanes.
Generation of α-Boryl Radicals and Their Conjugate Addition to Enones: Transition-Metal-Free Alkylation of gem-Diborylalkanes. Chemistry. 2020 Oct 16;: Authors: Wu C, Bao Z, Dou B, Wang J Abstract A transition-metal-free method for the alkylation of gem-diborylalkanes with alpha, beta-unsaturated ketones has been developed. It is demonstrated that the alpha-boryl radicals can be generated efficiently from gem-diborylalkanes with the aid of catechol and oxidants. The alpha-boryl radicals formed through such process can be engaged in conjugate addition reaction with alpha,beta-unsaturated ketones....
Source: Chemistry - October 16, 2020 Category: Chemistry Authors: Wu C, Bao Z, Dou B, Wang J Tags: Chemistry Source Type: research

Characterizing Polyoxovanadate-alkoxide Clusters Using Vanadium K-edge X-ray Absorption Spectroscopy.
Abstract A number of technologies would benefit from developing inorganic compounds and materials with specific electronic and magnetic exchange properties. Unfortunately, designing compounds with these properties is difficult because metal···metal coupling schemes are hard to predict and control. Fully characterizing communication between metals in existing compounds that exhibit interesting properties could provide valuable insight and advance those predictive capabilities. One such class of molecules are the series of Lindqvist iron-functionalized and hexavanadium polyoxovanadate-alkoxide c...
Source: Chemistry - October 16, 2020 Category: Chemistry Authors: Kozimor SA, Meyer RL, Greer SM, Blake AV, Cary SK, Ditter AS, Daly SR, Li F, Matson EM, Mocko V, Seidler GT, Stein BW, Weinstein SD Tags: Chemistry Source Type: research

Silica supported phosphine gold complexes as an efficient catalytic system for a dearomative spirocyclization.
bal B Abstract The combination of metal catalyst and inorganic silica frames provides a greener approach for recyclable catalysis. Herein, chiral silica nanohelices were successfully employed to covalently graft three phosphine gold chloride complexes. The resulting 3D ensembles showed chiroptical properties that allowed the monitoring of the supported ligands. T he heterogeneous gold chloride catalysts in cooperation with silver triflate exhibited a high reactivity in various reactions, especially for the spirocyclization of aryl alkynoate esters when a catalytic loading of 0.05 %mol can be employed. The heteroge...
Source: Chemistry - October 16, 2020 Category: Chemistry Authors: Cao Z, Scalabre A, Nlate S, Buffière S, Oda R, Pouget E, Bibal B Tags: Chemistry Source Type: research

A nanoprobe based on gated mesoporous silica nanoparticles for the selective and sensitive detection of benzene metabolite t,t-muconic acid in urine.
ute;nez-Máñez R Abstract Benzene is a highly toxic aromatic hydrocarbon. Inhaling benzene can cause dizziness, vertigo, headaches, aplasia, mutations and, in the most extreme cases, cancer. Trans, trans-muconic acid (t,t-MA) is one of the metabolization products of benzene.  Although different analytical methods have been reported for the determination of t,t-MA, these are often expensive, require trained personnel, are not suitable for on-site measurements, and use hazardous organic solvents. For these reasons, the development of reliable, selective and sensitive methods for rapid and in situ d...
Source: Chemistry - October 16, 2020 Category: Chemistry Authors: Domínguez M, Blandez JF, Lozano-Torres B, de la Torre C, Licchelli M, Mangano C, Amendola V, Sancenón F, Martínez-Máñez R Tags: Chemistry Source Type: research

Enhancement of Photocatalytic Activity for Hydrogen Production by Surface Modification of Pt-TiO2 Nanoparticles with a Double Layer of Photosensitizers.
Abstract To investigate the effect of the surface structure of dye-sensitized photocatalyst nanoparticles, we prepared three types of Ru(II)-photosensitizer(PS)-double-layered Pt-cocatalyst-loaded TiO 2 nanoparticles with different surface structures, Zr- RuCP 6 -Zr- RuP 6 @ N  wt%Pt-TiO 2 , RuCP 6 -Zr- RuP 6 @ N  wt%Pt-TiO 2 , and RuCP 2 -Zr- RuP 6 @ N  wt%Pt-TiO 2 ( N = 0.2, 1, and 5), and evaluated their photocatalytic H 2 evolution activity in the presence of redox-reversible iodide (I - ) as the electron donor. Although the driving force of the electron injection from I - to the photooxidized R...
Source: Chemistry - October 16, 2020 Category: Chemistry Authors: Yoshimura N, Kobayashi A, Yoshida M, Kato M Tags: Chemistry Source Type: research

Pnictogen-functionalised C1-Ligands: MC-ARn (n = 0,1,2,3).
Abstract The chemistry of transition metal carbynes, LnM≡CR, has historically been dominated by species bearing hydrocarbyl or amino 'R' substituents, with other elements appearing only sporadically. In recent years carbynes and related 'C1' species bearing other main-group substituents, particularly heavier elements of the p-block, have begun to emerge. This review details the chemistry of heavier pnictogen-functionalised C1 ligands, MCARn (A = P, As, Sb, Bi; n = 0-3), including their syntheses, properties and reactivities, and how these are distinguished from more traditional carbyne complexes. Recent deve...
Source: Chemistry - October 16, 2020 Category: Chemistry Authors: Hill AF, Colebatch AL, Frogley BJ, Onn CS Tags: Chemistry Source Type: research

Sensory Perception of non-Deuterated and Deuterated Organic Compounds.
Abstract The chemical background of olfactory perception has been subject of intensive research, but no available model can fully explain the sense of smell. There are also inconsistent results on the role of the isotopology of molecules. In experiments with human subjects it was found that the isotope effect is weak with acetone and D6-acetone. In contrast, clear differences were obvious in the perception of octanoic acid and D15-octanoic acid. Furthermore, a trained sniffer dog was initially able to distinguish between these isotopologues of octanoic acid. In chromatographic measurements, the respective deuterat...
Source: Chemistry - October 15, 2020 Category: Chemistry Authors: Salthammer T, Monegel F, Schulz N, Uhde E, Grimme S, Seibert J, Hohm U, Palm WU Tags: Chemistry Source Type: research

Boronic acid-mediated activity control of split 10-23 DNAzymes.
In this study, we designed new split 10-23 DNAzymes made of two non-functional fragments, the first one carrying a boronic acid group at its 5' end, while the other one is composed of a ribonucleotide at its 3' end. We demonstrate herein that the addition of Mg2+ ions leads to the assembly of the fragments, which in turn induces the formation of a new boronate internucleoside linkage that restores the DNAzyme activity. A systematic evaluation has been performed that identified the most performant system. Our results highlight key features for an efficient control of DNAzymes activity through the formation of boronate linka...
Source: Chemistry - October 15, 2020 Category: Chemistry Authors: Smietana M, Debiais M, Lelievre A, Vasseur JJ, Müller S Tags: Chemistry Source Type: research

Chalice-type tridentate silicon Lewis acids of C3 symmetry in a single step starting from hexadehydrotri-benzo[12]annulene.
Abstract Tridentate Lewis acids with aligned functions were syn-thesized based on the rigid framework hexadehydrotribenzo[12]annu-lene. The backbone and its fluorinated analogue were synthesised in one-pot syntheses, with alkyne deprotection and Sonogashira cross coupling reaction being carried out in one step. Hydrosilylation of the annulene with chlorohydrosilanes proceeded highly selectively and afforded rigid poly-Lewis acids with three SiCl 3 or SiCl 2 Me substitu-ents perfectly oriented to one side of the molecule in a single step. The progress of hydrosilylation was investigated by time-correlated NMR spect...
Source: Chemistry - October 15, 2020 Category: Chemistry Authors: Mitzel NW, Schwartzen A, Weddeling JH, Langosch J, Neumann B, Stammler G Tags: Chemistry Source Type: research

Structural Snapshots of π-arene Bonding in a Gold Germylene Cation.
In this study we have accessed the metalogermylenium cation [(PMe 2 Ar Dipp2 )AuGe(Ar Dipp2 )Cl] + ( 4 + ) (Ar Dipp2 = C 6 H 3 -2,6-(C 6 H 3 -2,6- i Pr 2 ) 2 ) that has been structurally characterized with three different non-coordinating counteranions. These studies provide for the first time dynamic information about the conformational rearrangement that characterizes π-arene bonding thorough a series of X-ray diffraction structural snapshots. Computational studies reveal the weak character of the π-arene bonding ( ca . 2 kcal/mol) that can be described as the donation from a π C=C bond toward the empty p valenc...
Source: Chemistry - October 15, 2020 Category: Chemistry Authors: Bajo S, Alcaide MM, López-Serrano J, Campos J Tags: Chemistry Source Type: research

N-truncated A β peptides impact on Cu and Cu(Aβ)-generated ROS: Cu(I) matters !
N-truncated Aβ peptides impact on Cu and Cu(Aβ)-generated ROS: Cu(I) matters ! Chemistry. 2020 Oct 15;: Authors: Esmieu C, Ferrand G, Borghesani V, Hureau C Abstract The in vitro Cu(Aβ 1-x ) induced ROS production has been extensively and thoroughly studied. Conversely, the ability of N-truncated isoforms of Aβ to alter the Cu-induced ROS production has been overlooked even though they are main constituents of amyloid plaques found in the human brain. N-truncated peptides at the positions 4 and 11 (Aβ 4-x and Aβ 11-x ) contain an amino-terminal copper and nickel (ATCUN) b...
Source: Chemistry - October 15, 2020 Category: Chemistry Authors: Esmieu C, Ferrand G, Borghesani V, Hureau C Tags: Chemistry Source Type: research