Showing posts with label o2012. Show all posts
Showing posts with label o2012. Show all posts

Thursday, November 29, 2012

La Profecía del Ekasilicio y un Sonethelio Semejante



La profecía del Ekasilicio:


Del libro del profeta Mendeleiev:   1,6-32

Yo, Mendeleiev, vi a un enviado del cielo bajar, su poder era inmenso y con sus transistores y fotodetectores iluminaba la Tierra, sus amplificadores regocijaban multitudes enardecidas, se hacían radares e innovadora óptica de él, y su forma cristalina, gris y brillante traía paz a los enfermos.

Estén atentos y busquen en las minas pueblo de Alemania, que entre sus hijos estará quien descubra al treintaidosavo súbdito del universo, un elegido del grupo cuatro para mostrarnos su Bandgap, quien a pesar de su dureza para guiar nos confiará óxidos anfóteros y cinco isotopos estables.

Esto sucederá para confirmar el nuevo orden de los elementos y favorecerá la fe de los hombres en él, abrácense los unos a los otros que la hora se acerca.

Palabra del Señor, gloria a ti, Universo.




Sonethelio Semejante:


No importa si es cada eclipse solar
Que puedo verte volar, no importa,
Mas si las voces agudas de van,
No estás y dos negaciones no afirman.

Hexagonales no importan ni tus formas,
Si eres tres o cuatro o seis, si eres radioactivo,
Si eres fusión de hidrogeno que, así te admiro,
Aunque no me quieras, inicialmente me importas.


Si pudieras no ser superfluo y frio,
Si vieras al mundo gracioso y vivo,
Pequeño cariño mío, déjate vivir.


Y es que no te entiendes ni a ti mismo,
Así a nadie le pasa por la nariz,
Menos por los ojos tu noble existir.

Brillantes 9,10-diboroantracenos


Influence of the Bridging Elements on the Optical Properties of Linked 9,10-Dihydro-9,10-diboraanthracenesAbstract Image

29/noviembre/2012
Paulina Levario

Starting from the monofunctionalized 9,10-dihydro-9,10-diboraanthracene derivatives MesB(C6H4)2BX (X = H, Br), the bridged systems MesB(C6H4)2B–L–B(C6H4)2BMes have been synthesized with L = −C(H)═C(H)(p-C6Me4)C(H)═C(H)– (5), −C≡C(p-C6Me4)C≡C– (6), and −(p-C6H4)(p-C6Me4)(p-C6H4)– (7). The compounds were characterized by NMR, IR, UV/vis, and fluorescence spectroscopy. The vinyl- and phenylboranes 5 and 7 are pale yellow solids, whereas the alkynylborane 6 possesses a bright yellow color. The emission maxima of57 in toluene are λmax(em) 477, 460, and 461 nm with quantum yields f of 0.02, 0.30, and 0.04, respectively. Alkynylborane 6 was found to be the least air- and moisture-sensitive of the three derivatives.

Para mayor información:

Influence of the Bridging Elements on the Optical Properties of Linked 9,10-Dihydro-9,10-diboraanthracenes

Estera Januszewski, Michael Bolte, Hans-Wolfram Lerner, and Matthias Wagner
Organometallics Article ASAP
DOI: 10.1021/om300990z
Publication Date (Web): November 20, 2012
Copyright © 2012 American Chemical Society

Inorgánica para el Alzheimer...


Reactivity of Diphenylpropynone Derivatives Toward Metal-Associated Amyloid-β Species

Abstract Image

29/septiembre/2012
Paulina Levario

In Alzheimer’s disease (AD), metal-associated amyloid-β (metal–Aβ) species have been suggested to be involved in neurotoxicity; however, their role in disease development is still unclear. To elucidate this aspect, chemical reagents have been developed as valuable tools for targeting metal–Aβ species, modulating the interaction between the metal and Aβ, and subsequently altering metal–Aβ reactivity. Herein, we report the design, preparation, characterization, and reactivity of two diphenylpropynone derivatives (DPP1 and DPP2) composed of structural moieties for metal chelation and Aβ interaction (bifunctionality). The interactions of these compounds with metal ions and Aβ species were confirmed by UV–vis, NMR, mass spectrometry, and docking studies. The effects of these bifunctional molecules on the control of in vitro metal-free and metal-induced Aβ aggregation were investigated and monitored by gel electrophoresis and transmission electron microscopy (TEM). Both DPP1 and DPP2 showed reactivity toward metal–Aβ species over metal-free Aβ species to different extents. In particular, DPP2, which contains a dimethylamino group, exhibited greater reactivity with metal–Aβ species than DPP1, suggesting a structure-reactivity relationship. Overall, our studies present a new bifunctional scaffold that could be utilized to develop chemical reagents for investigating metal–Aβ species in AD.

Para mayor información:

Reactivity of Diphenylpropynone Derivatives Toward Metal-Associated Amyloid-β Species

Amit S. Pithadia, Akiko Kochi, Molly T. Soper, Michael W. Beck, Yuzhong Liu, Sanghyun Lee, Alaina S. DeToma, Brandon T. Ruotolo, and Mi Hee Lim
Inorganic Chemistry Article ASAP
DOI: 10.1021/ic302084g
Publication Date (Web): November 15, 2012
Copyright © 2012 American Chemical Society

Synthesis and Crystal Structure of Cubic Ca16Si17N34


Synthesis and Crystal Structure of Cubic Ca16Si17N34

Abstract Image
29/noviembre/2012
Paulina Levario

Since the late 1960s, the exact structure of cubic calcium silicon nitride has been a source of debate. This paper offers evidence that the cubic phase CaSiN2 described in the literature is actually Ca16Si17N34. Presented here is a method for synthesizing single crystals of cubic-calcium silicon nitride from calcium nitride and elemental silicon under flowing nitrogen at 1500 °C. The colorless millimeter-sized crystals of Ca16Si17N34 with a refractive index (n25) = 1.590 were found to be cubic (a = 14.8882 Å) and belong to the space groupF4̅3m (216). The synthesis of bulk, powdered cubic-Ca16Si17N34 from calcium cyanamide and silicon is also discussed. Ca16Si17N34 is a relatively air-stable refractory ceramic. In contrast to the orthorhombic phase of CaSiN2, in which Ca2+ sits in octahedral sites, this cubic phase has Ca2+ in cubic sites that makes it an interesting host for new phosphors and gives rise to unique crystal field splitting.

Para mayor información:

Synthesis and Crystal Structure of Cubic Ca16Si17N34

Sandra M. Hick, Mattheu I. Miller, Richard B. Kaner, and Richard G. Blair
Inorganic Chemistry Article ASAP
DOI: 10.1021/ic300627q
Publication Date (Web): November 16, 2012
Copyright © 2012 American Chemical Society

Poker de Mn, Ni, Fe, Co, Fe


Structural and Spectroscopic Trends in a Series of Half-Sandwich Scorpionate Complexes

Abstract Image
29/noviembre/2012
Paulina Levario

Fifteen half-sandwich scorpionate complexes [(L)M(NCMe)3](BF4)n (L = tris(3,5-dimethylpyrazol-1-yl)methane, TpmMe,Men = 2, 1M, M = Mn, Fe, Co, Ni; L = tris(3-phenylpyrazol-1-yl)methane, TpmPhn = 2, 2M, M = Mn, Fe, Co, Ni; L = hydrotris(3,5-dimethylpyrazol-1-yl)borate, [TpMe,Me]n = 1, 3M, M = Fe, Co, Ni; L = hydrotris(3-phenyl-5-methylpyrazol-1-yl)borate, [TpPh,Me]n = 1, 4M, M = Mn, Fe, Co, Ni) were prepared by addition of the tripodal ligands to solvated [M(NCMe)x]2+ (M = Mn, x = 4; M = Fe, Co, Ni, x = 6) precursor complexes. The product complexes were characterized by 1H NMR (except M = Mn), UV–vis–NIR, and FTIR spectroscopy. The structures of 2Mn2Ni3Fe3Co, and 4Fe were determined by X-ray crystallography. The data were consistent with complexes of high-spin divalent metal ions in idealized piano-stool geometries in all cases. Consequent lability of the acetonitrile ligands will enable use of these complexes as synthetic precursors and as catalysts. Comparison to previously reported structures of 1Fe1Co2Fe, and 2Co, the triflate salt analogues of 4Co and 4Ni, as well as related sandwich complexes (e.g., [(TpMe,Me)2M]) and solvated metal dications [M(NCMe)6]2+ reveals numerous trends in M–N bond lengths. Primary among these are the Irving–Williams series, with significant structural effects also arising from ligand charge and sterics. Systematic trends in spectroscopic data were also observed which further elucidate these issues.

Para mayor información:

Structural and Spectroscopic Trends in a Series of Half-Sandwich Scorpionate Complexes

Shengwen Liang, Haoshuang Wang, Tapash Deb, Jeffrey L. Petersen, Gordon T. Yee, and Michael P. Jensen
Inorganic Chemistry Article ASAP
DOI: 10.1021/ic301409s
Publication Date (Web): November 19, 2012
Copyright © 2012 American Chemical Society

Brillan, los traizolatos brillan


Homoleptic Lanthanide 1,2,3-Triazolates 2–3[Ln(Tz*)3] and Their Diversified Photoluminescence Properties

Abstract Image
29/noviembre/2012
Paulina Levario

The series of homoleptic lanthanide 1,2,3-triazolates 3[Ln(Tz*)3] (Ln3+ = lanthanide cation, Tz* = 1,2,3-triazolate anion, C2H2N3) is completed by synthesis of the three-dimensional (3D) frameworks with Ln = La, Ce, Pr, Nd, and Sm, and characterization by X-ray powder diffraction, differential thermal analysis-thermogravimetry (DTA/TG) investigations and molecular vibration analysis. In addition, α-2[Sm(Tz*)3], a two-dimensional polymorph of 3D β-3[Sm(Tz*)3], is presented including the single crystal structure. The 3D lanthanide triazolates form an isotypic series of the formula 3[Ln(Tz*)3] ranging from La to Lu, with the exception of Eu, which forms a mixed valent metal organic framework (MOF) of different structure and the constitution 3[Eu(Tz*)6+x(Tz*H)2–x]. The main focus of this work is put on the investigation of the photoluminescence behavior of lanthanide 1,2,3-triazolates3[Ln(Tz*)3] and illuminates that six different luminescence phenomena can be found for one series of isotypic compounds. The luminescence behavior of the majority of these compounds is based on the photoluminescence properties of the organic linker molecules. Differing properties are observed for 3[Yb(Tz*)3], which exhibits luminescence properties based on charge transfer transitions between the linker and Yb3+ ions, and for 3[Ce(Tz*)3] and 3[Tb(Tz*)3], in which the luminescence properties are a combination of the ligand and the lanthanide metal. In addition, strong inner-filter effects are found in the ligand emission bands that are attributed to reabsorption of the emitted light by the trivalent lanthanide ions. Antenna effects of varying efficiency are present indicated by the energy being transferred to the lanthanide ions subsequent to excitation of the ligand. 3[Ce(Tz*)3] shows a 5d-4f induced intense blue emission upon excitation with UV light, while3[Tb(Tz*)3] shows emission in the green region of the visible spectrum, which can be identified with 4f-4f-transitions typical for Tb3+ ions.

Para mayor información:

Homoleptic Lanthanide 1,2,3-Triazolates ∞2–3[Ln(Tz*)3] and Their Diversified Photoluminescence Properties

J.-Christoph Rybak, Larissa V. Meyer, Julian Wagenhöfer, Gerhard Sextl, and Klaus Müller-Buschbaum
Inorganic Chemistry Article ASAP
DOI: 10.1021/ic301482e
Publication Date (Web): November 21, 2012
Copyright © 2012 American Chemical Society

l- and d-[Ln(HCO2)(SO4)(H2O)]n (Ln = La, Ce, Pr, Nd, and Eu): Chiral Enantiomerically 3D Architectures Constructed by Double −[Ln–O]n– Helices


l- and d-[Ln(HCO2)(SO4)(H2O)]n (Ln = La, Ce, Pr, Nd, and Eu): Chiral Enantiomerically 3D Architectures Constructed by Double −[Ln–O]n– HelicesAbstract Image

29/septiembre/2012
Paulina Levario

A total of 10 three-dimensional chiral coordination compounds l- and d-[Ln(HCO2)(SO4)(H2O)]n (Ln = La, Ce, Pr, Nd, and Eu) have been synthesized without any chiral auxiliary and characterized by IR, thermogravimetric, and elemental analyses. Their structures were determined by single-crystal X-ray structural analysis, which shows that l-[Ln(HCO2)(SO4)(H2O)]n (Ln = La, Ce, Pr, Nd, and Eu) crystallize in space group P43 and are laevogyrate and isostructural. The chiral frameworks of l-[Ln(HCO2)(SO4)(H2O)]n are constructed from l-helical Ln–O cluster chains, while adjacent l-type helical −[Ln–O]n– chains are connected through O–Ln–O linkages to form chiral intertwined Ln–O double helices of left-handedness.d-[Ln(HCO2)(SO4)(H2O)]n crystallize in space group P41, and their chiral frameworks consist of d-helical Ln–O cluster chains. The observed second-harmonic-generation efficiencies of [La(HCO2)(SO4)(H2O)]n, Ce(HCO2)(SO4)(H2O)]n, [Pr(HCO2)(SO4)(H2O)]n, [Nd(HCO2)(SO4)(H2O)]n, and [Eu(HCO2)(SO4)(H2O)]n are 0.7, 0.8, 0.7, 0.5, and 0.7 times that of urea, respectively. It is particularly interesting that [Pr(HCO2)(SO4)(H2O)]n shows good two-photon absorption.

Para mayor información:

l- and d-[Ln(HCO2)(SO4)(H2O)]n (Ln = La, Ce, Pr, Nd, and Eu): Chiral Enantiomerically 3D Architectures Constructed by Double −[Ln–O]n– Helices

Weiwei Ju, Deng Zhang, Dunru Zhu, and Yan Xu
Inorganic Chemistry Article ASAP
DOI: 10.1021/ic302134m
Publication Date (Web): November 26, 2012
Copyright © 2012 American Chemical Society

 NEODIMIO  ¡no te lo pierdas!