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https://www.readbyqxmd.com/read/28514507/hydrogen-bond-involving-cavity-nh-protons-drives-supramolecular-oligomerization-of-amido-corroles
#1
Daniel T Gryko, Rafał Orłowski, Mariusz Tasior, Barbara Ventura, Olga Staszewska-Krajewska, Wojciech Schilf, Michał Cyrański, Łukasz Dobrzycki
Trans-A2B-Corroles with amide substituents at different positions versus the macrocyclic core have been synthesized. Their self-organizing properties have been comprehensively evaluated both in solid-state and in solution. The rigid arrangement of the amide functionality with the corrole ring led to the formation of strong intramolecular interactions and precluded intermolecular interactions. Replacement of sterically hindered C6F5 substituents at positions 5 and 15 with smaller electron-withdrawing CO2Me groups resulted in significant changes in the self-assembly pattern...
May 17, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28510440/fundamental-characterization-of-the-micellar-self-assembly-of-sophorolipid-esters
#2
Amanda Koh, Katherine Todd, Ezekiel Sherbourne, Richard A Gross
Surfactants are ubiquitous constituents of commercial and biological systems that function based on complex structure-dependent interactions. Sophorolipid (SL) n-alkyl esters (SL-esters) comprise a group of modified naturally derived glycolipids from Candida bombicola. Herein, micellar self-assembly behavior as a function of SL-ester chain length was studied. Surface tensions as low as 31.2 mN/m and critical micelle concentrations (CMCs) as low as 1.1µM were attained for diacetylated SL-decyl ester (dASL-DE) and SL-octyl ester, respectively...
May 16, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28509541/synthesis-characterization-and-variable-temperature-nmr-studies-of-silver-i-complexes-for-selective-nitrene-transfer
#3
Minxue Huang, Joshua R Corbin, Nicholas S Dolan, Charles G Fry, Anastasiya I Vinokur, Ilia A Guzei, Jennifer M Schomaker
An array of silver complexes supported by nitrogen-donor ligands catalyze the transformation of C═C and C-H bonds to valuable C-N bonds via nitrene transfer. The ability to achieve high chemoselectivity and site selectivity in an amination event requires an understanding of both the solid- and solution-state behavior of these catalysts. X-ray structural characterizations were helpful in determining ligand features that promote the formation of monomeric versus dimeric complexes. Variable-temperature (1)H and DOSY NMR experiments were especially useful for understanding how the ligand identity influences the nuclearity, coordination number, and fluxional behavior of silver(I) complexes in solution...
May 16, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28508392/polyoxometalate-engineered-building-blocks-with-gold-cores-for-the-self-assembly-of-responsive-water-soluble-nanostructures
#4
Yizhan Wang, Manoj Raula, Yifeng Wang, Offer Zeiri, Sourav Chakraborty, Gal Gan-Or, Eyal Gadot, Ira A Weinstock
The controlled assembly of gold nanoparticles (AuNPs) with the size of quantum dots into predictable structures is extremely challenging as it requires the quantitatively and topologically precise placement of anisotropic domains on their small, approximately spherical surfaces. We herein address this problem by using polyoxometalate leaving groups to transform 2 nm diameter gold cores into reactive building blocks with hydrophilic and hydrophobic surface domains whose relative sizes can be precisely tuned to give dimers, clusters, and larger micelle-like organizations...
May 16, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28507679/-ag115s34-sch2c6h4-t-bu-47-dpph-6-synthesis-crystal-structure-and-nmr-investigations-of-a-soluble-silver-chalcogenide-nanocluster
#5
Sebastian Bestgen, Olaf Fuhr, Ben Breitung, Venkata Sei Kiran Chakravadhanula, Gisela Guthausen, Frank Hennrich, Wen Yu, Manfred M Kappes, Peter W Roesky, Dieter Fenske
With the aim to synthesize soluble cluster molecules, the silver salt of (4-(tert-butyl)phenyl)methanethiol [AgSCH2C6H4(t) Bu] was applied as a suitable precursor for the formation of a nanoscale silver sulfide cluster. In the presence of 1,6-(diphenylphosphino)hexane (dpph), the 115 nuclear silver cluster [Ag115S34(SCH2C6H4(t) Bu)47(dpph)6] was obtained. The molecular structure of this compound was elucidated by single crystal X-ray analysis and fully characterized by spectroscopic techniques. In contrast to most of the previously published cluster compounds with more than a hundred heavy atoms, this nanoscale inorganic molecule is soluble in organic solvents, which allowed a comprehensive investigation in solution by UV-Vis spectroscopy and one- and two-dimensional NMR spectroscopy including (31)P/(109)Ag-HSQC and DOSY experiments...
March 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28504171/tuneable-catechin-functionalisation-of-carbohydrate-polymers
#6
Susan Oliver, Aziidah Jofri, Donald S Thomas, Orazio Vittorio, Maria Kavallaris, Cyrille Boyer
In this contribution, we present a strategy to functionalise three natural carbohydrate polymers (dextran - a neutral polymer, sodium alginate - an anionic polymer and chitosan - a cationic polymer) with catechin with excellent degrees of functionality. In a first step, the carbohydrate polymers were oxidised by sodium periodate to yield aldehyde functionalised carbohydrate polymers. The presence of aldehyde groups was exploited to attach catechin by an acid catalysed nucleophilic reaction. The degree of catechin functionalisation could be easily tuned by varying the acid concentration in the reaction mixture, achieving catechin functionalisation levels of up to 48% for dextran aldehyde catechin, 35% for chitosan-aldehyde-catechin and 22% for sodium alginate aldehyde catechin...
August 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28492211/raised-adenosine-deaminase-in-the-cerebrospinal-fluid-a-tool-for-the-diagnosis-of-tuberculous-meningitis-in-developing-countries
#7
Purti A Saini, Preeti R Chakrabarti, Dosi Shilpi, Gambhir Shankhini, Gupta Priyanka, Tignath Gargi
CONTEXT: The rapid diagnosis followed by the early treatment of tuberculous meningitis (TBM) is important in preventing fatal outcomes. The mainstay of diagnosis lies in cerebrospinal fluid (CSF) analysis, radiological investigations, and clinical findings. AIM: The present study was conducted to determine the efficacy, sensitivity, and specificity of raised adenosine deaminase (ADA) level in CSF to differentiate TBM from non-TBM cases as a rapid, cost-effective, and noninvasive test...
January 2017: Nigerian Postgraduate Medical Journal
https://www.readbyqxmd.com/read/28491062/a-kinetic-study-of-cd83-reveals-an-upregulation-and-higher-production-of-scd83-in-lymphocytes-from-pregnant-mice
#8
Katrin Regina Helene Packhäuser, Gleyder Roman-Sosa, Jens Ehrhardt, Diana Krüger, Marek Zygmunt, Damián Oscar Muzzio
For the normal development of pregnancy, a balance between immune tolerance and defense is crucial. However, the mechanisms mediating such a balance are not fully understood. CD83 is a transmembrane protein whose expression has been linked to anti-inflammatory functions of T and B cells. The soluble form of CD83, released by cleavage of the membrane-bound protein, has strong anti-inflammatory properties and was successfully tested in different mouse models. It is assumed that this molecule contributes to the establishment of immune tolerance...
2017: Frontiers in Immunology
https://www.readbyqxmd.com/read/28489394/surface-engineering-of-ultrathin-gold-nanowires-tailored-self-assembly-and-enhanced-stability
#9
El Said Abd ElFattah Nouh, Edwin A Baquero, Lise-Marie Lacroix, Fabien Delpech, Romuald Poteau, Guillaume Viau
Gold nanowires with a mean diameter of 1.7 nm were synthesized by reduction of HAuCl4 in a solution of oleylamine (OY) in hexane. A bilayer of oleylammonium chloride/oleylamine at the surface of the raw nanowires was evidenced by NMR and DOSY experiments. After washing a monolayer of oleylammonium chloride remained at the surface of the nanowires. The oleylammonium chloride layer could be progressively replaced by a phosphine shell as evidenced NMR and Diffusion Ordered Spectroscopy experiment (DOSY) experiments, in good agreement with the adsorption energies given by DFT calculations...
May 10, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28489257/unsaturated-long-chain-fatty-acids-are-preferred-ferritin-ligands-enhancing-iron-biomineralization
#10
Serena Zanzoni, Katiuscia Pagano, Mariapina D'Onofrio, Michael Assfalg, Silvia Ciambellotti, Caterina Bernacchioni, Paola Turano, Silvio Aime, Laura Ragona, Henriette Molinari
Ferritin is a ubiquitous nanocage protein, which can accommodate up to thousands of iron atoms inside its cavity. Besides its iron storage function, a new role as fatty acid binder has been proposed for this protein. The interaction of apo horse spleen ferritin (HoSF) with a variety of lipids has been here investigated through NMR ligand-based experiments, to provide new insights into the mechanism of ferritin/lipid interactions and the link with iron mineralization. 1D DOSY and STD NMR experiments established a stronger interaction of ferritin with unsaturated fatty acids with respect to saturated fatty acids, detergents and bile acids...
May 10, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28466908/exploring-the-solid-state-and-solution-structural-chemistry-of-the-utility-amide-potassium-hexamethyldisilazide-khmds
#11
Ana I Ojeda-Amador, Antonio J Martínez-Martínez, Gemma M Robertson, Stuart D Robertson, Alan R Kennedy, Charles T O'Hara
The structural chemistry of eleven donor complexes of the important Brønsted base potassium 1,1,1,3,3,3-hexamethyldisilazide (KHMDS) has been studied. Depending on the donor, each complex adopted one of five general structural motifs. Specifically, in this study the donors employed were toluene (to give polymeric 1 and dimeric 2), THF (polymeric 3), N,N,N',N'-tetramethylethylenediamine (TMEDA) (dimeric 4), (R,R)-N,N,N',N'-tetramethyl-1,2-diaminocyclohexane [(R,R)-TMCDA] (dimeric 5), 12-crown-4 (dimeric 6), N,N,N',N'-tetramethyldiaminoethyl ether (TMDAE) (tetranuclear dimeric 8 and monomeric 10), N,N,N',N'',N''-pentamethyldiethylenetriamine (PMDETA) (tetranuclear dimeric 7), tris[2-dimethyl(amino)ethyl]amine (Me6TREN) (tetranuclear dimeric 9) and tris{2-(2-methoxyethoxy)ethyl}amine (TMEEA) (monomeric 11)...
May 16, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28451098/neutral-iodotriazoles-as-scaffolds-for-stable-halogen-bonded-assemblies-in-solution
#12
Leonardo Maugeri, Julia Asencio-Hernández, Tomáš Lébl, David B Cordes, Alexandra M Z Slawin, Marc-André Delsuc, Douglas Philp
The halogen bond (XB) donor properties of neutral 1,4-diaryl-5-iodo-1,2,3-triazoles are explored using a combination of computational and experimental results and are shown to be competitive in halogen bonding efficiency with the classic pentafluoroiodobenzene XB donor. The SNAr reactivity of these donors permits the facile assembly of an iodotriazole functionalised with a 3-oxypyridine XB acceptor, thus generating a molecular scaffold capable of undergoing dimerisation through the formation of two halogen bonds...
October 1, 2016: Chemical Science
https://www.readbyqxmd.com/read/28446127/sample-size-and-power-determination-when-limited-preliminary-information-is-available
#13
Christine E McLaren, Wen-Pin Chen, Thomas D O'Sullivan, Daniel L Gillen, Min-Ying Su, Jeon H Chen, Bruce J Tromberg
BACKGROUND: We describe a novel strategy for power and sample size determination developed for studies utilizing investigational technologies with limited available preliminary data, specifically of imaging biomarkers. We evaluated diffuse optical spectroscopic imaging (DOSI), an experimental noninvasive imaging technique that may be capable of assessing changes in mammographic density. Because there is significant evidence that tamoxifen treatment is more effective at reducing breast cancer risk when accompanied by a reduction of breast density, we designed a study to assess the changes from baseline in DOSI imaging biomarkers that may reflect fluctuations in breast density in premenopausal women receiving tamoxifen...
April 26, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/28430280/potassium-complexes-supported-by-monoanionic-tetradentate-amino-phenolate-ligands-synthesis-structure-and-catalysis-in-the-ring-opening-polymerization-of-rac-lactide
#14
Chenhui Yao, Yang Yang, Shaoan Xu, Haiyan Ma
A series of potassium complexes bearing monoanionic tetradentate amino-phenolate ligands, [LK]2 (L = {(2-R(1))C6H4CH2N[(CH2)2R(2)]CH2(4-R(4)-6-R(3))C6H2O-}, R(1) = NMe2, R(2) = NEt2, R(3) = CPh3, R(4) = Me (1); R(1) = R(2) = NEt2, R(3) = CPh3, R(4) = Me (2); R(1) = NMe2, R(2) = NEt2, R(3) = R(4) = cumyl (4); R(1) = R(2) = OMe, R(3) = (t)Bu, R(4) = Me (6); L = (2-NMe2)C6H4CH2N[[CH2-(S)-1-butylpyrrolidinyl]CH2(4-Me-6-CPh3)C6H2O-] (3)), have been synthesized via reactions of KN(SiMe3)2 and 1 equiv. of the corresponding aminophenols...
May 9, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28402655/self-assembly-of-extended-head-to-tail-triangular-pt3-macrocycles-into-nanotubes
#15
Zhengyu Chen, Brian J Sahli, Mark J MacLachlan
New pyridylsalicylaldimine-based ligands with extended conjugation have been synthesized. The reaction of these ligands with K2PtCl4 yielded triangular Pt3 macrocycles rather than the anticipated Pt4 macrocycles. The macrocycles have been analyzed in solution by variable-temperature and variable-concentration (1)H NMR, NOESY, and DOSY spectroscopy studies. These investigations show that the macrocycles aggregate at room temperature in solution by an entropy-driven process. In the solid state, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and transmission electron microscopy studies show that the macrocycles aggregate into nanotubular structures...
April 12, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28402286/longitudinal-optical-monitoring-of-blood-flow-in-breast-tumors-during-neoadjuvant-chemotherapy
#16
Jeffrey Martin Cochran, So Chung, Anaïs Leproux, Wesley Baker, David Busch, Angela DeMichele, Julia Tchou, Bruce Tromberg, Arjun Yodh
We measure tissue blood flow markers in breast tumors during neoadjuvant chemotherapy and investigate their correlation to pathologic complete response in a pilot longitudinal patient study (n=4). Tumor blood flow is quantified optically by diffuse correlation spectroscopy (DCS), and tissue optical properties, blood oxygen saturation, and total hemoglobin concentration are derived from concurrent diffuse optical spectroscopic imaging (DOSI). The study represents the first longitudinal DCS measurement of neoadjuvant chemotherapy in humans over the entire course of treatment; it therefore offers a first correlation between DCS flow indices and pathologic complete response...
April 12, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28394584/hierarchy-of-pyrophosphate-functionalized-uranyl-peroxide-nanocluster-synthesis
#17
Mateusz Dembowski, Christopher A Colla, Sarah Hickam, Anna F Oliveri, Jennifer E S Szymanowski, Allen G Oliver, William H Casey, Peter C Burns
Herein, we report a new salt of a pyrophosphate-functionalized uranyl peroxide nanocluster {U24Pp12} (1) exhibiting Oh molecular symmetry both in the solid and solution. Study of the system yielding 1 across a wide range of pH by single-crystal X-ray diffraction, small-angle X-ray scattering, and a combination of traditional (31)P and diffusion-ordered spectroscopy (DOSY) NMR affords unprecedented insight into the amphoteric chemistry of this uranyl peroxide system. Key results include formation of a rare binary {U24}·{U24Pp12} (3) system observed under alkaline conditions, and evidence of acid-promoted decomposition of {U24Pp12} (1) followed by spatial rearrangement and condensation of {U4} building blocks into the {U32Pp16} (2) cluster...
April 10, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28394573/introducing-stereogenic-centers-to-group-xiv-metallatranes
#18
Britta Glowacki, Michael Lutter, Hazem Alnasr, Rana Seymen, Wolf Hiller, Klaus Jurkschat
The syntheses of the novel amino alcohols NH(CH2CMe2OH)2(CMe2CH2OH) (1) and N(CH2CMe2OH)(CMe2CH2OH)(CH2CH2OH) (2) as well as the stannatranes N(CH2CMe2O)(CMe2CH2O)(CH2CH2O)SnX (3, X = Ot-Bu), N(CH2CMe2O)3SnOC(O)C9H13O2, 4, and germatranes N(CH2CMe2O)(CMe2CH2O)(CH2CH2O)GeX (5, X = OEt; 6, X = Br) are reported. The compounds were characterized by (1)H, (13)C (1-6), (119)Sn (3, 4), and (15)N (2, 3, 5) NMR and IR spectroscopy, electrospray ionization mass spectrometry, and single crystal X-ray diffraction analysis...
April 10, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28382756/direct-self-assembly-of-a-2d-and-3d-star-of-david
#19
Bo Song, Zhe Zhang, Kun Wang, Chih-Hao Hsu, Olapeju Bolarinwa, Jing Wang, Yiming Li, Guang-Qiang Yin, Edwin Rivera, Hai-Bo Yang, Changlin Liu, Bingqian Xu, Xiaopeng Li
Two- and three-dimensional metallosupramolecules shaped like a Star of David were synthesized by the self-assembly of a tetratopic pyridyl ligand with a 180° diplatinum(II) motif and Pd(II) ions, respectively. In contrast to other strategies, such as template-directed synthesis and stepwise self-assembly, this design enables the formation of 2D and 3D structures in one step and high yield. The structures were characterized by both one-dimensional ((1) H, (13) C, (31) P) and two-dimensional (COSY, NOESY, DOSY) NMR spectroscopy, ESI-MS, ion-mobility mass spectrometry (IM-MS), AFM, and TEM...
May 2, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28358162/ligands-and-complexes-based-on-piperidine-and-their-exploitation-of-the-ring-opening-polymerisation-of-rac-lactide
#20
Paul McKeown, James Brown-Humes, Matthew G Davidson, Mary F Mahon, Timothy J Woodman, Matthew D Jones
A range of ligands based upon 2-(aminomethyl)piperidine have been successfully complexed to Mg(ii), Zn(ii) and group IV metal centres. These complexes have been characterised both in solution and solid state with different coordination geometries realised dependant on the nature of the ligand. For the Mg(ii) and Zn(ii) complexes, M(1-2)2, were isolated and analysed by DOSY NMR spectroscopy. These ligands also furnished diastereomeric group IV complexes, M(1-2)2(O(i)Pr)2. Group IV salalen and salan complexes, M(4-5)(OR)2 were also found to be diastereomeric in nature, with either β-cis or α-cis geometriesrespectively...
April 11, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
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