5 research outputs found
Regioselective, Stereoselective, and Conformationally Controlled Synthesis of (Ρ<sup>4</sup>-Tetraarylcyclobutadiene)(Ρ<sup>5</sup>-carbomethoxycyclopentadienyl)cobalt Metallocenes
The FriedelâCrafts reaction of (Ρ<sup>4</sup>-tetraphenylcyclobutadiene)(Ρ<sup>5</sup>-carbomethoxycyclopentadienyl)cobalt with acid chlorides/aluminum chloride resulted exclusively in <i>para</i>-phenyl acylation. Both monoacylated (1.1 equiv of RCOCl/AlCl<sub>3</sub>) and tetraacylated products (>4 equiv of RCOCl/AlCl<sub>3</sub>) were synthesized. Reaction of PhCC(<i>o</i>-RC<sub>6</sub>H<sub>4</sub>) (R = Me, <i>i</i>-Pr) with Na(C<sub>5</sub>H<sub>4</sub>CO<sub>2</sub>Me) and CoCl(PPh<sub>3</sub>)<sub>3</sub> gave predominantly (Ρ<sup>4</sup>-1,3-diaryl-2,4-diphenylcyclobutadiene)(Ρ<sup>5</sup>-carbomethoxycyclopentadienyl)cobalt metallocenes (1,3-[<i>trans</i>] vs 1,2-[<i>cis</i>] selectivity up to 6:1). Conformational control of FriedelâCrafts reactions on the major isomers gave exclusively <i>para</i>-acylation of the unsubstituted phenyl groups
Structural Variability in Multifunctional Metal Xylenediaminetetraphosphonate Hybrids
Two new families of divalent metal
hybrid derivatives from the aromatic tetraphosphonic acids 1,4- and
1,3-<i>bis</i>(aminomethyl)Âbenzene-<i>N</i>,<i>N</i>â˛-<i>bis</i>(methylenephosphonic acid),
(H<sub>2</sub>O<sub>3</sub>PCH<sub>2</sub>)<sub>2</sub>âNâCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>CH<sub>2</sub>âNÂ(CH<sub>2</sub>PO<sub>3</sub>H<sub>2</sub>)<sub>2</sub> (designated herein as <b><i>p</i>-H<sub>8</sub>L</b> and <b><i>m</i>-H<sub>8</sub>L</b>) have been synthesized by crystallization
at room temperature and hydrothermal conditions. The crystal structures
of MÂ[(HO<sub>3</sub>PCH<sub>2</sub>)<sub>2</sub>NÂ(H)ÂCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>CH<sub>2</sub>NÂ(H)Â(CH<sub>2</sub>PO<sub>3</sub>H)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>]¡2H<sub>2</sub>O (M = Mg, Co, and Zn), <b>Mâ(<i>p</i>-H<sub>6</sub>L)</b>, and MÂ[(HO<sub>3</sub>PCH<sub>2</sub>)<sub>2</sub>NÂ(H)ÂCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>CH<sub>2</sub>NÂ(H)Â(CH<sub>2</sub>PO<sub>3</sub>H)<sub>2</sub>]¡<i>n</i>H<sub>2</sub>O (M = Ca, Mg, Co, and Zn and <i>n</i> = 1â1.5), <b><b>Mâ(<i>m</i>-H<sub>6</sub>L)</b></b>,
were solved ab initio by synchrotron powder diffraction data using
the direct methods and subsequently refined using the Rietveld method.
The crystal structure of the isostructural <b><b>Mâ(<i>p</i>-H<sub>6</sub>L)</b></b> is constituted by organicâinorganic
monodimensional chains where the phosphonate moiety acts as a bidentate
chelating ligand bridging two metal octahedra. <b><b>Mâ(<i>m</i>-H<sub>6</sub>L)</b></b> compounds exhibit a 3D pillared
open-framework with small 1D channels filled with water molecules.
These channels are formed by the pillaring action of the organic ligand
connecting adjacent layers through the phosphonate oxygens. Thermogravimetric
and X-ray thermodiffraction analyses of <b><b>Mâ(<i>p</i>-H<sub>6</sub>L)</b></b> showed that the integrity
of their crystalline structures is maintained up to 470 K, without
significant reduction of water content, while thermal decomposition
takes place above 580 K. The utility of <b><b>Mâ(<i>p</i>-H<sub>6</sub>L)</b></b> (M = Mg and Zn) hybrid materials
in corrosion protection was investigated in acidic aqueous solutions.
In addition, the impedance data indicate both families of compounds
display similar proton conductivities (Ď âź 9.4 Ă
10<sup>â5</sup> S¡cm<sup>â1</sup>, at 98% RH and
297 K), although different proton transfer mechanisms are involved
Structural Variability in Multifunctional Metal Xylenediaminetetraphosphonate Hybrids
Two new families of divalent metal
hybrid derivatives from the aromatic tetraphosphonic acids 1,4- and
1,3-<i>bis</i>(aminomethyl)Âbenzene-<i>N</i>,<i>N</i>â˛-<i>bis</i>(methylenephosphonic acid),
(H<sub>2</sub>O<sub>3</sub>PCH<sub>2</sub>)<sub>2</sub>âNâCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>CH<sub>2</sub>âNÂ(CH<sub>2</sub>PO<sub>3</sub>H<sub>2</sub>)<sub>2</sub> (designated herein as <b><i>p</i>-H<sub>8</sub>L</b> and <b><i>m</i>-H<sub>8</sub>L</b>) have been synthesized by crystallization
at room temperature and hydrothermal conditions. The crystal structures
of MÂ[(HO<sub>3</sub>PCH<sub>2</sub>)<sub>2</sub>NÂ(H)ÂCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>CH<sub>2</sub>NÂ(H)Â(CH<sub>2</sub>PO<sub>3</sub>H)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>]¡2H<sub>2</sub>O (M = Mg, Co, and Zn), <b>Mâ(<i>p</i>-H<sub>6</sub>L)</b>, and MÂ[(HO<sub>3</sub>PCH<sub>2</sub>)<sub>2</sub>NÂ(H)ÂCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>CH<sub>2</sub>NÂ(H)Â(CH<sub>2</sub>PO<sub>3</sub>H)<sub>2</sub>]¡<i>n</i>H<sub>2</sub>O (M = Ca, Mg, Co, and Zn and <i>n</i> = 1â1.5), <b><b>Mâ(<i>m</i>-H<sub>6</sub>L)</b></b>,
were solved ab initio by synchrotron powder diffraction data using
the direct methods and subsequently refined using the Rietveld method.
The crystal structure of the isostructural <b><b>Mâ(<i>p</i>-H<sub>6</sub>L)</b></b> is constituted by organicâinorganic
monodimensional chains where the phosphonate moiety acts as a bidentate
chelating ligand bridging two metal octahedra. <b><b>Mâ(<i>m</i>-H<sub>6</sub>L)</b></b> compounds exhibit a 3D pillared
open-framework with small 1D channels filled with water molecules.
These channels are formed by the pillaring action of the organic ligand
connecting adjacent layers through the phosphonate oxygens. Thermogravimetric
and X-ray thermodiffraction analyses of <b><b>Mâ(<i>p</i>-H<sub>6</sub>L)</b></b> showed that the integrity
of their crystalline structures is maintained up to 470 K, without
significant reduction of water content, while thermal decomposition
takes place above 580 K. The utility of <b><b>Mâ(<i>p</i>-H<sub>6</sub>L)</b></b> (M = Mg and Zn) hybrid materials
in corrosion protection was investigated in acidic aqueous solutions.
In addition, the impedance data indicate both families of compounds
display similar proton conductivities (Ď âź 9.4 Ă
10<sup>â5</sup> S¡cm<sup>â1</sup>, at 98% RH and
297 K), although different proton transfer mechanisms are involved
High Proton Conductivity in a Flexible, Cross-Linked, Ultramicroporous Magnesium Tetraphosphonate Hybrid Framework
Multifunctional materials, especially those combining
two or more properties of interest, are attracting immense attention
due to their potential applications. MOFs, metal organic frameworks,
can be regarded as multifunctional materials if they show another
useful property in addition to the adsorption behavior. Here, we report
a new multifunctional light hybrid, MgH<sub>6</sub>ODTMP¡2H<sub>2</sub>OÂ(DMF)<sub>0.5</sub> (<b>1</b>), which has been synthesized
using the tetraphosphonic acid H<sub>8</sub>ODTMP, octamethylenediamine-<i>N</i>,<i>N</i>,<i>N</i>â˛,<i>N</i>â˛-tetrakisÂ(methylenephosphonic acid), by high-throughput
methodology. Its crystal structure, solved by Patterson-function direct
methods from synchrotron powder X-ray diffraction, was characterized
by a 3D pillared open framework containing cross-linked 1D channels
filled with water and DMF. Upon H<sub>2</sub>O and DMF removal and
subsequent rehydration, MgH<sub>6</sub>ODTMP¡2H<sub>2</sub>O
(<b>2</b>) and MgH<sub>6</sub>ODTMP¡6H<sub>2</sub>O (<b>3</b>) can be formed. These processes take place through crystallineâquasi-amorphousâcrystalline
transformations, during which the integrity of the framework is maintained.
A water adsorption study, at constant temperature, showed that this
magnesium tetraphosphonate hybrid reversibly equilibrates its lattice
water content as a function of the water partial pressure. Combination
of the structural study and gas adsorption characterization (N<sub>2</sub>, CO<sub>2</sub>, and CH<sub>4</sub>) indicates an ultramicroporous
framework. High-pressure CO<sub>2</sub> adsorption data are also reported.
Finally, impedance data indicates that <b>3</b> has high proton
conductivity Ď = 1.6 Ă 10<sup>â3</sup> S cm<sup>â1</sup> at <i>T</i> = 292 K at âź100% relative
humidity with an activation energy of 0.31 eV
High Proton Conductivity in a Flexible, Cross-Linked, Ultramicroporous Magnesium Tetraphosphonate Hybrid Framework
Multifunctional materials, especially those combining
two or more properties of interest, are attracting immense attention
due to their potential applications. MOFs, metal organic frameworks,
can be regarded as multifunctional materials if they show another
useful property in addition to the adsorption behavior. Here, we report
a new multifunctional light hybrid, MgH<sub>6</sub>ODTMP¡2H<sub>2</sub>OÂ(DMF)<sub>0.5</sub> (<b>1</b>), which has been synthesized
using the tetraphosphonic acid H<sub>8</sub>ODTMP, octamethylenediamine-<i>N</i>,<i>N</i>,<i>N</i>â˛,<i>N</i>â˛-tetrakisÂ(methylenephosphonic acid), by high-throughput
methodology. Its crystal structure, solved by Patterson-function direct
methods from synchrotron powder X-ray diffraction, was characterized
by a 3D pillared open framework containing cross-linked 1D channels
filled with water and DMF. Upon H<sub>2</sub>O and DMF removal and
subsequent rehydration, MgH<sub>6</sub>ODTMP¡2H<sub>2</sub>O
(<b>2</b>) and MgH<sub>6</sub>ODTMP¡6H<sub>2</sub>O (<b>3</b>) can be formed. These processes take place through crystallineâquasi-amorphousâcrystalline
transformations, during which the integrity of the framework is maintained.
A water adsorption study, at constant temperature, showed that this
magnesium tetraphosphonate hybrid reversibly equilibrates its lattice
water content as a function of the water partial pressure. Combination
of the structural study and gas adsorption characterization (N<sub>2</sub>, CO<sub>2</sub>, and CH<sub>4</sub>) indicates an ultramicroporous
framework. High-pressure CO<sub>2</sub> adsorption data are also reported.
Finally, impedance data indicates that <b>3</b> has high proton
conductivity Ď = 1.6 Ă 10<sup>â3</sup> S cm<sup>â1</sup> at <i>T</i> = 292 K at âź100% relative
humidity with an activation energy of 0.31 eV