10 research outputs found
Solvent-Controlled Syntheses, Structure, and Magnetic Properties of Trinuclear Mn(II)-Based Metal–Organic Frameworks
Solvothermal reactions of manganese(II) salts with hexa[4-(carboxyphenyl)oxamethyl]-3-oxapentane
acid (H<sub>6</sub>L) afforded a family of porous metal–organic
frameworks, namely, Mn<sub>3</sub>(L)(DMA)<sub>4</sub>·2DMA (<b>1</b>, <i>C</i>2/<i>c</i>), Mn<sub>3</sub>(L)(H<sub>2</sub>O)<sub>2</sub>(DMF)<sub>2</sub>·8DMF (<b>2</b>, <i>Cc</i>), and Mn<sub>3</sub>(L)(H<sub>2</sub>O)<sub>2</sub>(DMF)·4DMF (<b>3</b>, <i>P</i>2<sub>1</sub>/<i>c</i>). All compounds have been characterized
by elemental analysis and thermogravimetric analysis and structurally
confirmed by single-crystal X-ray diffractions. Their structures consist
of three types of trinuclear Mn<sup>II</sup> subunits, which are further
bridged by the carboxylic ligand, resulting in two types of topological
nets (pts and sra). All of the Mn<sup>II</sup><sub>3</sub> subunits
are terminally coordinated by solvent molecules. The structure of
the Mn<sup>II</sup><sub>3</sub> core in <b>1</b> is symmetric
with an inversion center, whereas those in <b>2</b> and <b>3</b> display a symmetry-breaking phenomenon. Their magnetic behaviors
exhibit interesting variations, in which the local net magnetization
at low temperature increases gradually from <b>1</b> to <b>3</b>. Such magnetic evolution behavior in trinuclear subunits
has never been observed previously
Construction of Three-Dimensional Cobalt(II)-Based Metal–Organic Frameworks by Synergy between Rigid and Semirigid Ligands
Solvothermal assembly of Co(II) ion, a semirigid tetrahedral
carboxylate
ligand tetrakis[(4-carboxyphenyl)oxamethyl]methane acid (H<sub>4</sub>L), and rigid linear bidentate linker 1,4-di(1<i>H</i>-imidazol-1-yl)benzene
(dib) or 4,4′-di(1<i>H</i>-imidazol-1-yl)-1,1′-biphenyl
(dibp) yields four novel metal–organic frameworks (<b>1</b>–<b>4</b>) with different topological connections. [Co<sub>2</sub>(L)(dib)]·3DMF (<b>1</b>) is a 2-fold interpenetrating <i>sqc</i>422 network and contains 3-dimensional interconnected
channels along [100], [010], and [110] directions; [Co<sub>4</sub>(L)<sub>2</sub>(dib)<sub>3</sub>(H<sub>2</sub>O)<sub>4</sub>]·4H<sub>2</sub>O (<b>2</b>) is a three-dimensional 3,4,4-connected
new topology with 5-fold interpenetration; [Co<sub>2</sub>(L)(dibp)]·5DMF
(<b>3</b>) and Co<sub>2</sub>(L)(dibp)<sub>2</sub> (<b>4</b>) are formed in the presence of dibp linker; they feature three-dimensional
novel topologies based on 4,6-connection and 4,4-connection, respectively,
and no interpenetration is observed. It is demonstrated that interpenetration
is accessible simply by changing auxiliary ligands and solvents. Magnetic
studies reveal that complexes <b>1</b> and <b>3</b> exhibit
antiferromagnetic behavior
Construction of Three-Dimensional Cobalt(II)-Based Metal–Organic Frameworks by Synergy between Rigid and Semirigid Ligands
Solvothermal assembly of Co(II) ion, a semirigid tetrahedral
carboxylate
ligand tetrakis[(4-carboxyphenyl)oxamethyl]methane acid (H<sub>4</sub>L), and rigid linear bidentate linker 1,4-di(1<i>H</i>-imidazol-1-yl)benzene
(dib) or 4,4′-di(1<i>H</i>-imidazol-1-yl)-1,1′-biphenyl
(dibp) yields four novel metal–organic frameworks (<b>1</b>–<b>4</b>) with different topological connections. [Co<sub>2</sub>(L)(dib)]·3DMF (<b>1</b>) is a 2-fold interpenetrating <i>sqc</i>422 network and contains 3-dimensional interconnected
channels along [100], [010], and [110] directions; [Co<sub>4</sub>(L)<sub>2</sub>(dib)<sub>3</sub>(H<sub>2</sub>O)<sub>4</sub>]·4H<sub>2</sub>O (<b>2</b>) is a three-dimensional 3,4,4-connected
new topology with 5-fold interpenetration; [Co<sub>2</sub>(L)(dibp)]·5DMF
(<b>3</b>) and Co<sub>2</sub>(L)(dibp)<sub>2</sub> (<b>4</b>) are formed in the presence of dibp linker; they feature three-dimensional
novel topologies based on 4,6-connection and 4,4-connection, respectively,
and no interpenetration is observed. It is demonstrated that interpenetration
is accessible simply by changing auxiliary ligands and solvents. Magnetic
studies reveal that complexes <b>1</b> and <b>3</b> exhibit
antiferromagnetic behavior
Rational Assembly of Co/Cd-MOFs Featuring Topological Variation
Three
different carboxylate ligands of 4,4′-biphthalic acid
(<b>H</b><sub><b>4</b></sub><b>L</b>, linear), 4,4′-axydiphthalic
acid (<b>H</b><sub><b>4</b></sub><b>L</b><sup><b>O</b></sup>, V-shaped), and thiophene-2,5-dicarboxylic acid (<b>H</b><sub><b>2</b></sub><b>L</b><sup><b>S</b></sup>, V-shaped and heteroatomic ring) were selected as two-connected
nodes to react with Co(II) or Cd(II) nitrates in the presence of 1,3,5-tris(1-imidazolyl)benzene
(<b>tib</b>, Y-shaped and tridentate). Hydrothermal reactions
in distilled water afforded seven new Co(Cd)-MOFs, namely, M(<b>tib</b>)(H<sub>2</sub>L)(H<sub>2</sub>O)<sub>2</sub>·H<sub>2</sub>O (M = Co, <b>1</b>; Cd, <b>2)</b>, M<sub>2</sub>(<b>tib</b>)<sub>2</sub>(H<sub>2</sub>L<sup>O</sup>)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub> (M = Co, <b>3</b>; Cd, <b>4</b>), Co<sub>2</sub>(<b>tib</b>)(L<sup>O</sup>)·H<sub>2</sub>O (<b>5</b>), Co(<b>tib</b>)(L<sup>S</sup>)·2H<sub>2</sub>O (<b>6</b>), and Cd(<b>tib</b>)(L<sup>S</sup>)·3H<sub>2</sub>O (<b>7</b>). Of particular interest,
they exhibit four interesting nets. <b>1</b>–<b>2</b> and <b>3</b>–<b>4</b> feature binodal (3,4) and
(3,3,4,4)-connected nets if H-bonds are taken into account, respectively. <b>5</b> is composed of a two-dimensional metal-L<sup>O</sup> layer
and a one-dimensional metal-tib chain and simplified into a 4-nodal
(3,4,4,5)-connected net. <b>6</b> and <b>7</b> feature
rare binodal (3,5)-connected {3.7<sup>2</sup>}{3<sup>2</sup>.7<sup>5</sup>.8<sup>3</sup>} <b>fsf/polar</b> net and (3,5)-connected
{6<sup>3</sup>}{6<sup>9</sup>.8} <b>hms</b> net. Structural
analyses show that each type of compound with the same metal components
and <b>tib</b> ligands exhibit such interesting topological
variations, which are derived from different orientations of three
carboxylate ligands. Other properties of these compounds were also
investigated, such as elemental and thermogravimetric analyses, photoluminescent
spectroscopy, and magnetic behavior
Structural Variation within Heterometallic Uranyl Hybrids Based on Flexible Alkyldiphosphonate Ligands
Five novel zinc uranyl
diphosphonates have been hydrothermally
synthesized by using a series of flexible diphosphonate ligands, including
ethane-1,2-diyldiphosphonic acid (H<sub>4</sub>EDP), propane-1,3-diyldiphosphonic
acid (H<sub>4</sub>PDP), and butane-1,4-diyldiphosphonic acid (H<sub>4</sub>BDP). Compound Zn(H<sub>2</sub>tib)(UO<sub>2</sub>)<sub>2</sub>(EDP)(HEDP)(H<sub>2</sub>EDP)<sub>0.5</sub>·3H<sub>2</sub>O
(<b>EDP-ZnU1</b>, tib = 1,3,5-tri(1H-imidazol-1-yl)benzene)
comprises dimeric U<sub>2</sub>O<sub>12</sub> unit condensed by two
UO<sub>7</sub> pentagonal bipyramids, which are further connected
by Zn-centered polyhedra and EDP ligands resulting in a 3-dimensional
framework. Compound [Zn(bipy)(H<sub>2</sub>O)](UO<sub>2</sub>)(PDP)
(<b>PDP-ZnU1</b>, bipy = 2,2′-bipyridine) also features
U<sub>2</sub>O<sub>12</sub> dimers and Zn-centered polyhedra, but
a layered arrangement is formed. Different from that in <b>PDP-ZnU1</b>, the uranium exists in the form of UO<sub>6</sub> tetragonal bipyramid
and is surrounded by four PDP ligands to generate the layered structure
of Zn(bipy)(UO<sub>2</sub>)(PDP) (<b>PDP-ZnU2</b>). ZnO<sub>2</sub>N<sub>2</sub> tetrahedra are connected on both sides of the
layers. Both Zn<sub>2</sub>(phen)<sub>4</sub>(UO<sub>2</sub>)<sub>3</sub>(BDP)(HBDP)<sub>2</sub>·4H<sub>2</sub>O (<b>BDP-ZnU1</b>, phen = 1,10-phenanthroline) and Zn<sub>2</sub>(bipy)<sub>2</sub>(UO<sub>2</sub>)<sub>3</sub>(HBDP)<sub>2</sub>(H<sub>2</sub>BDP)<sub>2</sub> (<b>BDP-ZnU2</b>) contain U<sub>2</sub>O<sub>12</sub> dimers and UO<sub>6</sub> tetragonal bipyramids. In <b>BDP-ZnU1</b>, uranyl centers are bridged by BDP to form a 2-dimensional structure,
on which Zn(phen)<sub>2</sub> are decorated. Whereas in <b>BDP-ZnU2</b>, uranyl phosphonate layers are connected by bridging ZnO<sub>3</sub>N<sub>2</sub> to produce framework structure. All of these compounds
have been investigated by IR and photoluminescent spectroscopy. Their
characteristic green light emissions have been attributed to transition
properties of uranyl dications
Rational Assembly of Co/Cd-MOFs Featuring Topological Variation
Three
different carboxylate ligands of 4,4′-biphthalic acid
(<b>H</b><sub><b>4</b></sub><b>L</b>, linear), 4,4′-axydiphthalic
acid (<b>H</b><sub><b>4</b></sub><b>L</b><sup><b>O</b></sup>, V-shaped), and thiophene-2,5-dicarboxylic acid (<b>H</b><sub><b>2</b></sub><b>L</b><sup><b>S</b></sup>, V-shaped and heteroatomic ring) were selected as two-connected
nodes to react with Co(II) or Cd(II) nitrates in the presence of 1,3,5-tris(1-imidazolyl)benzene
(<b>tib</b>, Y-shaped and tridentate). Hydrothermal reactions
in distilled water afforded seven new Co(Cd)-MOFs, namely, M(<b>tib</b>)(H<sub>2</sub>L)(H<sub>2</sub>O)<sub>2</sub>·H<sub>2</sub>O (M = Co, <b>1</b>; Cd, <b>2)</b>, M<sub>2</sub>(<b>tib</b>)<sub>2</sub>(H<sub>2</sub>L<sup>O</sup>)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub> (M = Co, <b>3</b>; Cd, <b>4</b>), Co<sub>2</sub>(<b>tib</b>)(L<sup>O</sup>)·H<sub>2</sub>O (<b>5</b>), Co(<b>tib</b>)(L<sup>S</sup>)·2H<sub>2</sub>O (<b>6</b>), and Cd(<b>tib</b>)(L<sup>S</sup>)·3H<sub>2</sub>O (<b>7</b>). Of particular interest,
they exhibit four interesting nets. <b>1</b>–<b>2</b> and <b>3</b>–<b>4</b> feature binodal (3,4) and
(3,3,4,4)-connected nets if H-bonds are taken into account, respectively. <b>5</b> is composed of a two-dimensional metal-L<sup>O</sup> layer
and a one-dimensional metal-tib chain and simplified into a 4-nodal
(3,4,4,5)-connected net. <b>6</b> and <b>7</b> feature
rare binodal (3,5)-connected {3.7<sup>2</sup>}{3<sup>2</sup>.7<sup>5</sup>.8<sup>3</sup>} <b>fsf/polar</b> net and (3,5)-connected
{6<sup>3</sup>}{6<sup>9</sup>.8} <b>hms</b> net. Structural
analyses show that each type of compound with the same metal components
and <b>tib</b> ligands exhibit such interesting topological
variations, which are derived from different orientations of three
carboxylate ligands. Other properties of these compounds were also
investigated, such as elemental and thermogravimetric analyses, photoluminescent
spectroscopy, and magnetic behavior
A Dual-Functional Luminescent MOF Sensor for Phenylmethanol Molecule and Tb<sup>3+</sup> Cation
A highly luminescent
porous metal–organic framework Cd<sub>3</sub>(L)<sub>2.5</sub>(4-PTZ)(DMF)<sub>3</sub>, labeled as <b>NBU-9</b>, has been
designedly synthesized based on Cd(NO<sub>3</sub>)<sub>2</sub>·4H<sub>2</sub>O and mixed ligands of 4-(1<i>H</i>-tetrazol-5-yl)pyridine
(4-HPTZ) with N-coordinated sites and thiophene-2,5-dicarboxylic acid
(H<sub>2</sub>L) with heteroatomic (S) ring and carboxylate groups
in <i>N</i>,<i>N</i>-dimethylformamide (DMF) at
100 °C for 3 days. The interesting
result is that this compound <b>NBU-9</b> can be also obtained
via the mixed raw materials of Cd(NO<sub>3</sub>)<sub>2</sub>·4H<sub>2</sub>O, 4-cyanopyridine, NaN<sub>3</sub>, and H<sub>2</sub>L under
solvothermal condition at a higher temperature of 140 °C for
3 days, involving <i>in situ</i> ligand synthesis of 4-HPTZ.
Its structure was indentified by single-crystal X-ray study, powder
X-ray diffraction, element analysis, and TGA results. Structural analysis
shows that the three-dimensional framework of <b>NBU-9</b> contains
cubic channels of 9.59 × 10.26 Å<sup>2</sup> covered by
a large number of open S- and O-coordinated sites and can be simplified
into a 8-connected uninodal <i>eca</i> net with high potential
solvent accessible volumes of 34.1%. Its luminescent properties demonstrate
that <b>NBU-9</b> as a multifunctional sensory material realizes
the selective detection for the phenylmethanol molecule on the basis
of fluorescence quenching mechanism and effectively sensitizing the
visible emitting of the Tb<sup>3+</sup> cation based on luminescence
enhancement
Hierarchical Two-Dimensional Conductive Metal–Organic Framework/Layered Double Hydroxide Nanoarray for a High-Performance Supercapacitor
A novel
hierarchical nanoarray material based on a two-dimensional metal–organic
framework (Ni-CAT) and a layered double hydroxide (NiCo-LDH) was fabricated
on a nickel foam substrate. By taking advantage of the regular nanostructure
and making full use of the high porosity and excellent conductivity,
the hybrid material exhibits a high areal capacitance for a supercapacitor
(3200 mF cm<sup>–2</sup> at 1 mA cm<sup>–2</sup>)
An Ultrastable Metal–Organic Framework with Open Coordinated Sites Realizing Selective Separation toward Cationic Dyes in Aqueous Solution
A novel
Zn-based metal–organic framework (MOF) was synthesized from
the mixed ligands, 3,3′,5,5′-azoxybenzenetetracarboxylic
acid (H<sub>4</sub>AOBTC) and 1,4-bis(1<i>H</i>-benzo[d]imidazol-1-yl)benzene
(phenDIB) ligand. The crystal structure of the complex exhibits an
interpenetrated three-dimensional framework that can be simplified
as a (4,4)-connected 2-nodal <i>bbf</i> net. This MOF displays
extraordinary thermostability in boiling water for 12 h and chemical
stability in a wide pH range of 2–13. The most intriguing feature
is that it can successfully separate cationic dyes from mixed dye
molecules in aqueous solution with high effectivity and selectivity,
even for rhodamine B molecule with a large size. Furthermore, this
material is reusable, and the adsorbed dye molecules can be released
and recovered completely. It is very important for the practical application
from a view of environmental protection and resource recycling