22 research outputs found
Ligand-Promoted Rh(III)-Catalyzed Coupling of Aryl C–H Bonds with Arylboron Reagents
RhodiumÂ(III)-catalyzed
C–H arylation of arenes with phenylboronic
acid pinacol esters has been achieved using a readily removable <i>N</i>-pentafluorophenylbenzamide directing group for the first
time. The use of a bidentate phosphine ligand (Binap) significantly
increased the yield of the cross-coupling of C–H bonds with
organoboron reagents
La Charente
13 octobre 18851885/10/13 (A14,N5373)-1885/10/13.Appartient à l’ensemble documentaire : PoitouCh
Ligand-Promoted Rh(III)-Catalyzed Coupling of Aryl C–H Bonds with Arylboron Reagents
RhodiumÂ(III)-catalyzed
C–H arylation of arenes with phenylboronic
acid pinacol esters has been achieved using a readily removable <i>N</i>-pentafluorophenylbenzamide directing group for the first
time. The use of a bidentate phosphine ligand (Binap) significantly
increased the yield of the cross-coupling of C–H bonds with
organoboron reagents
Solvent-modulated zinc<sup>II</sup> networks with different stacking arrangements
<div><p>Two Zn<sup>II</sup> complexes, [Zn<sub>2</sub>(L)<sub>2</sub>(DMF)(H<sub>2</sub>O)<sub>2</sub>]·DMF (<b>1</b>) and [Zn(L)(DEF)]·DEF (<b>2</b>), were synthesized by solvothermal reactions using 4,4′-(2,3,5,6-tetramethylbenzene1,4-diyl)dibenzoic acid (H<sub>2</sub>L) and Zn(NO<sub>3</sub>)<sub>2</sub>·6H<sub>2</sub>O in different solvents of DMF, ethanol, and water for <b>1</b> and N,N-diethylformamide (DEF) for <b>2</b>. The L<sup>2−</sup> with different coordination modes connect [Zn<sub>2</sub>(COO)<sub>2</sub>] secondary building units (SBUs) to generate a wavy 2-D (4,4) network of <b>1</b> while in <b>2</b> there are paddlewheel [Zn<sub>2</sub>(COO)<sub>4</sub>] SBUs which are connected by L<sup>2−</sup> to form a planar 2-D (4,4) network. The 2-D layered structures show different stacking arrangements and are further linked by hydrogen bonding or C–H⋯π interactions to give 3-D architectures. The different structures and stacking arrangements of <b>1</b> and <b>2</b> result from different reaction solvents. Photoluminescence properties of the complexes were investigated.</p></div
Syntheses, Structures, and Sorption Properties of Metal–Organic Frameworks with 1,3,5-Tris(1-imidazolyl)benzene and Tricarboxylate Ligands
Seven
new frameworks [Co<sub>3</sub>(tib)<sub>2</sub>(BPT)<sub>2</sub>Â(H<sub>2</sub>O)<sub>2</sub>]·DMA·2.5H<sub>2</sub>O (<b>1</b>), [Co<sub>3</sub>(tib)<sub>2</sub>Â(BPT)<sub>2</sub>Â(H<sub>2</sub>O)<sub>2</sub>]·DMF·3H<sub>2</sub>O (<b>2</b>), [Ni<sub>3</sub>(tib)<sub>2</sub>Â(BPT)<sub>2</sub>Â(H<sub>2</sub>O)<sub>2</sub>]·DMF·1.5H<sub>2</sub>O (<b>3</b>), [Ni<sub>3</sub>(tib)<sub>2</sub>(BPT)<sub>2</sub>Â(H<sub>2</sub>O)<sub>6</sub>]·2H<sub>2</sub>O (<b>4</b>), [MnÂ(tib)Â(H<sub>2</sub>O)<sub>3</sub>]·HBPT·DMF·2H<sub>2</sub>O (<b>5</b>), [Ni<sub>3</sub>(tib)<sub>2</sub>(BTB)<sub>2</sub>Â(H<sub>2</sub>O)<sub>2</sub>]·14H<sub>2</sub>O (<b>6</b>), and [Co<sub>3</sub>(tib)<sub>2</sub>(BTB)<sub>2</sub>]·2DMF·6H<sub>2</sub>O (<b>7</b>) [tib = 1,3,5-trisÂ(1-imidazolyl)Âbenzene, H<sub>3</sub>BPT = biphenyl-3,4′,5-tricarboxylic
acid, H<sub>3</sub>BTB = 4,4′,4″-benzene-1,3,5-triyl-tribenzoic
acid, DMA = <i>N</i>,<i>N</i>-dimethylacetamide,
DMF = <i>N</i>,<i>N</i>-dimethylformamide] were
achieved and structurally characterized. <b>1</b>, <b>2</b>, and <b>3</b> are (3,3,4,4)-connected three-dimensional (3D)
frameworks with a point symbol of {8<sup>3</sup>}<sub>4</sub>{8<sup>5</sup>·12}Â{8<sup>6</sup>}<sub>2</sub>, while <b>4</b>, <b>6</b>, and <b>7</b> are also (3,3,4,4)-connected
3D nets but with different framework structures and topologies. <b>5</b> is a two-dimensional network, which is further joined together
by hydrogen bonds to generate a 3D supramolecular framework. Gas,
vapor, and dye adsorption properties of the frameworks were examined,
and <b>1</b>–<b>7</b> exhibit hysteretic and selective
adsorption of CO<sub>2</sub> over N<sub>2</sub>. Furthermore, <b>7</b> is a potential adsorbent for removing methylene blue in
the aqueous solution
Novel (3,4,6)-Connected Metal–Organic Framework with High Stability and Gas-Uptake Capability
A microporous and noninterpenetrated metal–organic
framework
[Cu<sub>3</sub>(L)<sub>2</sub>(DABCO)Â(H<sub>2</sub>O)]·15H<sub>2</sub>O·9DMF (<b>1</b>) has been synthesized using two
different ligands, [1,1′:3′,1″-terphenyl]-4,4″,5′-tricarboxylic
acid (H<sub>3</sub>L) and 1,4-diazabicyclo[2.2.2]Âoctane (DABCO). As
revealed by variable-temperature powder X-ray diffraction (VT-PXRD)
measurements, <i>N</i>,<i>N</i>′-ditopic
DABCO plays an important role for stabilization of the Cu–L
framework. The three-dimensional framework of <b>1</b> exhibits
high stability and excellent adsorption capacity for H<sub>2</sub> (54.3 mg g<sup>–1</sup> at 77 K and 20 bar), CO<sub>2</sub> (871 mg g<sup>–1</sup> at 298 K and 20 bar), CH<sub>4</sub> (116.7 mg g<sup>–1</sup>, 99 cm<sup>3</sup> (STP) cm<sup>–3</sup> at 298 K and 20 bar), and <i>n</i>-pentane
(686 mg g<sup>–1</sup> at 298 K and 1 bar). Interestingly,
the excellent selectivity toward CO<sub>2</sub> over N<sub>2</sub> at ambient temperature (273 and 298 K) and 1 bar makes complex <b>1</b> possess practical application in gas separation and purification
Novel (3,4,6)-Connected Metal–Organic Framework with High Stability and Gas-Uptake Capability
A microporous and noninterpenetrated metal–organic
framework
[Cu<sub>3</sub>(L)<sub>2</sub>(DABCO)Â(H<sub>2</sub>O)]·15H<sub>2</sub>O·9DMF (<b>1</b>) has been synthesized using two
different ligands, [1,1′:3′,1″-terphenyl]-4,4″,5′-tricarboxylic
acid (H<sub>3</sub>L) and 1,4-diazabicyclo[2.2.2]Âoctane (DABCO). As
revealed by variable-temperature powder X-ray diffraction (VT-PXRD)
measurements, <i>N</i>,<i>N</i>′-ditopic
DABCO plays an important role for stabilization of the Cu–L
framework. The three-dimensional framework of <b>1</b> exhibits
high stability and excellent adsorption capacity for H<sub>2</sub> (54.3 mg g<sup>–1</sup> at 77 K and 20 bar), CO<sub>2</sub> (871 mg g<sup>–1</sup> at 298 K and 20 bar), CH<sub>4</sub> (116.7 mg g<sup>–1</sup>, 99 cm<sup>3</sup> (STP) cm<sup>–3</sup> at 298 K and 20 bar), and <i>n</i>-pentane
(686 mg g<sup>–1</sup> at 298 K and 1 bar). Interestingly,
the excellent selectivity toward CO<sub>2</sub> over N<sub>2</sub> at ambient temperature (273 and 298 K) and 1 bar makes complex <b>1</b> possess practical application in gas separation and purification
Iodoarene-Catalyzed Stereospecific Intramolecular sp<sup>3</sup> C–H Amination: Reaction Development and Mechanistic Insights
A new
strategy is reported for intramolecular sp<sup>3</sup> C–H
amination under mild reaction conditions using iodoarene as catalyst
and <i>m</i>-CPBA as oxidant. This C–H functionalization
involving iodineÂ(III) reagents generated in situ occurs readily at
sterically hindered tertiary C–H bonds. DFT (M06-2X) calculations
show that the preferred pathway involves an iodonium cation intermediate
and proceeds via an energetically concerted transition state, through
hydride transfer followed by the spontaneous C–N bond formation.
This leads to the experimentally observed amination at a chiral center
without loss of stereochemical information
Iodoarene-Catalyzed Stereospecific Intramolecular sp<sup>3</sup> C–H Amination: Reaction Development and Mechanistic Insights
A new
strategy is reported for intramolecular sp<sup>3</sup> C–H
amination under mild reaction conditions using iodoarene as catalyst
and <i>m</i>-CPBA as oxidant. This C–H functionalization
involving iodineÂ(III) reagents generated in situ occurs readily at
sterically hindered tertiary C–H bonds. DFT (M06-2X) calculations
show that the preferred pathway involves an iodonium cation intermediate
and proceeds via an energetically concerted transition state, through
hydride transfer followed by the spontaneous C–N bond formation.
This leads to the experimentally observed amination at a chiral center
without loss of stereochemical information
Cucurbit[6]uril-Based Supramolecular Assemblies: Possible Application in Radioactive Cesium Cation Capture
Multidimensional supramolecular assemblies
based on cucurbitÂ[<i>n</i>]Âuril (<i>n</i> = 6
or 7) were constructed via
the outer-surface interactions of cucurbitÂ[<i>n</i>]Âurils
with the polyaromatic compound 4,4′,4″-benzene-1,3,5-triyl-tribenzoate
as a structure-directing agent. Most impressively, the cucurbit[6]Âuril-based
assembly exhibits high selectivity for capture of cesium cations among
the common alkali metal ions in a basic medium and releases the cesium
cations under acidic conditions. This reversible process enables possible
applications in cesium cation capture