41 research outputs found
Efficient and Selective Removal of Copper(II) from Aqueous Solution by a Highly Stable Hydrogen-Bonded Metal–Organic Framework
Copper(II)
is an indispensable element in nature, while exposure
to excessive Cu<sup>2+</sup> will potentially cause health issues.
It is imperative to develop new strategies for efficient Cu<sup>2+</sup> uptake from aqueous solution. Herein, a hydrogen-bonded metal–organic
framework (MOF) [(Zn<sub>3</sub>L<sub>3</sub>(H<sub>2</sub>O)<sub>6</sub>][(Na)(NO<sub>3</sub>)] (<b>1</b>) with high stability
was elaborately constructed. The uncoordinated carboxylate oxygen
atoms in the channels of MOF were designed as active sites to recognize
Cu<sup>2+</sup> and further coordinate with it. Without pretreatment,
MOF <b>1</b> demonstrated a relatively high adsorption capacity
(379.13 mg g<sup>–1</sup>), exceeding most Cu<sup>2+</sup> adsorbents.
Even with the existence of different metal ions and a high concentration
of interfering ions, highly selective adsorption of Cu<sup>2+</sup> can be achieved. Moreover, the excellent water stability together
with the high removal efficiency in the presence of coexisting ions
offers MOF <b>1</b> the possibility in practical application.
The mechanism for Cu<sup>2+</sup> selective adsorption was systematically
investigated by UV–vis, Fourier transform infrared, and fluorescence
lifetime techniques, which may originate from the strong interaction
between Cu<sup>2+</sup> and the carboxylate oxygen atoms. Our work
may open an avenue to develop MOFs into adsorbent materials for water
pollutants
High Efficiency and Fast Removal of Trace Pb(II) from Aqueous Solution by Carbomethoxy-Functionalized Metal–Organic Framework
Lead
(Pb) is one of the most widespread toxic heavy metals, and
how to quickly and completely remove trace Pb(II) is a global concern.
Herein, we prepared a novel metal–organic framework (MOF) {[Cd(ADB)L<sub>2</sub>]·1.5DMF·2H<sub>2</sub>O}<sub><i>n</i></sub> (<b>1</b>) decorated with carbomethoxy groups and investigated
the Pb(II) removal performance as well as the underlying mechanism.
The MOF exhibits a fast kinetics with the kinetic rate constant <i>k</i><sub>2</sub> of 0.162 g mg<sup>–1</sup> min<sup>–1</sup>, which is 1–3 orders of magnitude higher than
the reported Pb(II) adsorbent materials. In addition, even in a concentration
of 0.1 ppm, a high removal efficiency (96%) was still obtained after
the treatment with the metal–organic framework, and the concentration
was reduced to 0.004 ppm, which is well below the drinking water standard
of the World Health Organization (0.01 ppm). The possible adsorption
mechanism was systematically verified by Fourier-transform infrared
and X-ray photoelectron spectroscopy investigations. The significant
affinity between carbomethoxy groups and Pb(II) is responsible for
the good removal performance
Guest Molecule Release Triggers Changes in the Catalytic and Magnetic Properties of a Fe<sup>II</sup>-Based 3D Metal–Organic Framework
A Fe<sup>II</sup>-based metal–organic
framework (MOF), {[Fe<sub>2</sub>(pbt)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>]·2H<sub>2</sub>O}<sub><i>n</i></sub>, undergoes
an irreversible dehydration, which triggers changes in the catalytic
and magnetic properties of the MOF. These property changes are attributed
to the high-spin to low-spin transition of 7.1% center Fe<sup>II</sup>, which is demonstrated by <sup>57</sup>Fe Mössbauer, X-ray
photoelectron spectroscopy, and UV/vis absorption spectra
Three New Hg(II) Complexes Constructed From Mercapto- and Amino-Containing Triazole Ligands: Syntheses, Crystal Structures, and Luminescent Properties
<div><p>Three new mercury(II) complexes [HgI<sub>2</sub>(3-aptt)<sub>2</sub>] (1), [Hg(4-aptt)<sub>2</sub>] (2), and [Hg(a-mtt)<sub>2</sub>]·H<sub>2</sub>O (3) were synthesized based on three structurally related ligands: 4-amino-3-(3-pyridyl)-1H-1,2,4-triazole-5-thione (3-Haptt), 4-amino-3-(4-pyridyl)-5-mercapto-1,2,4-triazole (4-Haptt), and 4-amino-3-methyl-1,2,4-triazoline-5-thiadone (a-Hmtt). The structures of complexes 1–3 were determined by single-crystal X-ray diffraction techniques and further characterized by elemental analyses and IR spectra. The results reveal that these three complexes take mononuclear structures. And although various weak interactions, including N‒H···I and N···H‒O H-bondings as well as N<sub>trz</sub>···N<sub>py</sub> and π···π stacking, play significant roles in crystal structures, just these weak interactions link the mononuclear units into higher dimensional supramolecular networks. Their thermal stabilities and the solid state luminescent properties have also been discussed.</p></div
Effect of Organic Polycarboxylate Ligands on the Structures of a Series of Zinc(II) Coordination Polymers Based on a Conformational Bis-triazole Ligand
To explore the influence of six structurally different
polycarboxylate
ligands H<sub>2</sub>L<sup>1</sup> to H<sub>4</sub>L<sup>6</sup> in
the system Zn(II)/btmx, six coordination polymers, formulated as [Zn(btmx)(L<sup>1</sup>)]<sub><i>n</i></sub> (<b>1</b>), {[Zn(btmx)(L<sup>2</sup>)]·2H<sub>2</sub>O}<sub><i>n</i></sub> (<b>2</b>), {[Zn(btmx)(L<sup>3</sup>)]·1.5H<sub>2</sub>O}<sub><i>n</i></sub> (<b>3</b>), [Zn(btmx)(L<sup>4</sup>)]<sub><i>n</i></sub> (<b>4</b>), {[Zn<sub>4</sub>(btmx)<sub>3</sub>(L<sup>5</sup>)<sub>4</sub>(H<sub>2</sub>O)<sub>2</sub>]·4H<sub>2</sub>O}<sub><i>n</i></sub> (<b>5</b>), and [Zn(btmx)(H<sub>2</sub>L<sup>6</sup>)]<sub><i>n</i></sub> (<b>6</b>), have been obtained under similar
conditions (btmx = 1,4-bis(1,2,4-triazol-1-ylmethyl)-2,3,5,6-tetramethylbenzene,
H<sub>2</sub>L<sup>1</sup> = 1,3-benzenedicarboxylic acid, H<sub>2</sub>L<sup>2</sup> = 1,4-benzenedicarboxylic acid, H<sub>2</sub>L<sup>3</sup> = 1,3-adamantanedicarboxylic acid, H<sub>2</sub>L<sup>4</sup> <b>=</b> 1,3-adamantanediacetic acid, H<sub>2</sub>L<sup>5</sup> = 4,4′-oxidibenzoic acid, and H<sub>4</sub>L<sup>6</sup> =
3,3′,4,4′-benzophenone tetracarboxylic acid). The structure
determination reveals that complexes <b>1</b> and <b>4</b> are two-dimensional (2D) layered networks and exhibit typical (4,4)
topological nets. Complex <b>2</b> shows an undulating 2D (4,4)-network
with 2-fold interpenetration. Complex <b>3</b> possesses a three-dimensional
(3D) 3-fold interpenetrating 4-connected framework of 6<sup>6</sup>-<b>dia</b> topology. Both <b>5</b> and <b>6</b> have different 3D interpenetrated motifs generated by 2D →
3D interpenetration. Complex <b>5</b> belongs to a 3D framework
built from the interpenetration of 2D bilayers in an inclined mode,
while <b>6</b> involves a parallel interpenetration between
the adjacent 2D (4,4) layers. This work markedly indicates that the
effect of polycarboxylate ligands is significant in the construction
of these networks
Polynuclear Cd<sup>II</sup> Polymers: Crystal Structures, Topologies, and the Photodegradation for Organic Dye Contaminants
To systematically explore the effect
of polynuclear complexes on
photocatalytic degradation of the organic dyes, a series of coordination
complexes containing Cd<sup>II</sup> clusters, formulated as {[Cd<sub>3</sub>L<sub>2</sub>(H<sub>2</sub>O)<sub>5</sub>]·H<sub>2</sub>O}<sub><i>n</i></sub> (<b>1</b>), {[Cd<sub>3</sub>L<sub>2</sub>(hbmb)(H<sub>2</sub>O)<sub>2</sub>]·2.5H<sub>2</sub>O}<sub><i>n</i></sub> (<b>2</b>), {[Cd<sub>3</sub>L<sub>2</sub>(btbb)(H<sub>2</sub>O)<sub>2</sub>]·2EtOH·1.5H<sub>2</sub>O}<sub><i>n</i></sub> (<b>3</b>), and {[Cd<sub>6</sub>L<sub>4</sub>(bipy)<sub>2</sub>(H<sub>2</sub>O)<sub>6</sub>]·3H<sub>2</sub>O}<sub><i>n</i></sub> (<b>4</b>) (H<sub>3</sub>L = 3,4-bi(4-carboxyphenyl)-benzoic acid, hbmb =
1,1′-(1,6-hexane)bis(2-methylbenzimidazole), btbb = 1,4-bis(2-(4-thiazolyl)benzimidazole-1-ylmethyl)benzene,
4,4′-bipy = 4,4′-bipyridine), have been designed and
synthesized. Complex <b>1</b> based on trinuclear Cd<sup>II</sup> clusters exhibits a new (3,3,6)-connected 3D framework. <b>2</b> belongs to a (3,3,8,8)-connected tfz-d topology net with pillar-layered
frameworks assembled by two kinds of trinuclear Cd<sup>II</sup> clusters. <b>3</b> is a 3D pillar-layered framework, which features a (3,8)-connected
tfz-d net based upon one kind of trinuclear Cd<sup>II</sup> cluster. <b>4</b> presents a new 3D (3,6,10)-connected framework with dinuclear
and tetranuclear clusters. The photocatalytic properties of complexes <b>1</b>–<b>4</b> have been studied in detail. Remarkably, <b>1</b>–<b>4</b> all reveal good photocatalytic activity
in MB/MO degradation. The optical energy gap calculated by the diffuse
reflectivity spectra of <b>1</b>–<b>4</b> are consistent
with their degradation rates. Moreover, the experimental results further
demonstrate that the cluster complexes containing different kinds
of nuclei may exert different impact on the decomposition of disparate
organic dyes
Chiral Metallocycles Templated Novel Chiral Water Frameworks
An intentionally synthesized chiral terpyridyl ligand <i>S</i>-2(4-(2,6-di(pyridin-2-yl)pyridin-4-yl)-benzylamino)propanoic
acid
(H<sub>2</sub>L) was used to construct two chiral Ni<sup>II</sup> complexes,
[Ni<sub>2</sub>(HL)<sub>2</sub>(N<sub>3</sub>)(H<sub>2</sub>O)](N<sub>3</sub>)·19H<sub>2</sub>O (<b>1</b>) and [Ni<sub>2</sub>(HL)<sub>2</sub>(N<sub>3</sub>)<sub>2</sub>]·7H<sub>2</sub>O (<b>2</b>). Both complexes are
dinuclear metallocyclic complexes. The monoanionic form (HL)<sup>−</sup> of the chiral ligand coordinates to the metal centers in a bichelating
antiparallel fashion to form the metallomacrocycles where the chiral
metallocycles Ni<sub>2</sub>(HL)<sub>2</sub> template the formation
of a novel chiral 3D zeolite-like water framework with nanometer cages
trapping the metallocycles or anchor chiral water chains in the 1D
channels of a resulting chiral 3D supermolecule, respectively
Ni(II) Coordination Polymers Constructed from the Flexible Tetracarboxylic Acid and Different N‑Donor Ligands: Structural Diversity and Catalytic Activity
To seek the effect that condition of the complexes has on the manufacture
of the biaryl compounds, seven Ni(II) complexes, namely, {[Ni(L)<sub>0.5</sub>(bpa)(H<sub>2</sub>O)]·2H<sub>2</sub>O}<sub><i>n</i></sub> (<b>1</b>), {[Ni<sub>2</sub>(L)(dpp)<sub>2</sub>(H<sub>2</sub>O)]·4H<sub>2</sub>O}<sub><i>n</i></sub> (<b>2</b>), {[Ni(L)<sub>0.5</sub>(pbmb)(H<sub>2</sub>O)]·H<sub>2</sub>O}<sub><i>n</i></sub> (<b>3</b>), {[Ni<sub>2</sub>(L)(bmp)<sub>2</sub>(H<sub>2</sub>O)]·7H<sub>2</sub>O}<sub><i>n</i></sub> (<b>4</b>), {[Ni(L)<sub>0.5</sub>(pbib)<sub>1.5</sub>]·2H<sub>2</sub>O}<sub><i>n</i></sub> (<b>5</b>), {[Ni<sub>2</sub>(L)(pbib)<sub>1.5</sub>]·3H<sub>2</sub>O}<sub><i>n</i></sub> (<b>6</b>), and [Ni(L)<sub>0.5</sub>(beb)<sub>2</sub>(H<sub>2</sub>O)]<sub><i>n</i></sub> (<b>7</b>) (bpa = 1,2-bis(4-pyridyl)ethane, dpp = 1,3-di(4-pyridyl)propane,
pbmb = 1,1′-(1,3-propane)bis(2-methylbenzimidazole),
bmp = 1,5-bis(2-methylbenzimidazol) pentane, pbib = 1,4-bis(imidazol-1-ylmethyl)benzene,
beb = 1,4-bis(2-ethylbenzimidazol-1-ylmethyl)benzene), have
been gained through hydro(solvo)thermal reactions of 5,5′-(hexane-1,6-diyl)-bis(oxy)diisophthalic
acid ligand (H<sub>4</sub>L) with Ni(II) metal ions under the regulation
and control of six N-donor ligands. 3-fold interpenetrating complex <b>1</b> belongs to a (4,4)-connected 3D <i>bbf</i> net
with a vertex symbol of (6<sup>4</sup>·8<sup>2</sup>)(6<sup>6</sup>) topology. 3-fold interpenetrating complex <b>2</b> presents
a (4,4,4)-connected 3D <i>bbf</i> net with a Schläfli
symbol of (6<sup>6</sup>)<sub>2</sub>(6<sup>4</sup>·8<sup>2</sup>) topology. <b>3</b> features a (3,4)-connected <i>3,4L13</i> topology with a Schläfli symbol of (4·6<sup>2</sup>)(4<sup>2</sup>·6<sup>2</sup>·8<sup>2</sup>) topology. <b>4</b> possesses a (4,4,4)-connected <i>mog Moganite</i> 3D network
fabric, and the vertex symbol is (4·6<sup>4</sup>·8)<sub>2</sub>(4<sup>2</sup>·6<sup>2</sup>·8<sup>2</sup>). <b>5</b> takes on a (4,5)-connected architecture, and the
point symbol is (4·6<sup>9</sup>)(4<sup>2</sup>·6<sup>6</sup>·8<sup>2</sup>). <b>6</b> is a (4,7)-connected
framework, and the Schläfli symbol is (4<sup>5</sup>·5)(4<sup>7</sup>·5<sup>3</sup>·6<sup>11</sup>). <b>7</b> has
a (4,4)-connected <i>4,4L28</i> topology, and the point
(Schläfli) symbol is (4<sup>2</sup>·6<sup>4</sup>)(4·6<sup>4</sup>·8). A systematic structural comparison of <b>1</b>–<b>7</b> signifies that their frameworks can be regulated
through varied conformations of the flexible H<sub>4</sub>L ligand
and diverse N-donor ligands. Between the proximal Ni(II) ions, the
variable-temperature (2–300 K) magnetic susceptibilities of <b>6</b> display overall weak antiferromagnetic coupling. In the
complexes-catalyzed homocoupling reaction of iodobenzene, <b>3</b>, <b>5</b>, <b>6</b>, and <b>7</b> have been verified
to be effectual catalysts for the synthesis of the biaryl compounds
Effect of Organic Polycarboxylate Ligands on the Structures of a Series of Zinc(II) Coordination Polymers Based on a Conformational Bis-triazole Ligand
To explore the influence of six structurally different
polycarboxylate
ligands H<sub>2</sub>L<sup>1</sup> to H<sub>4</sub>L<sup>6</sup> in
the system Zn(II)/btmx, six coordination polymers, formulated as [Zn(btmx)(L<sup>1</sup>)]<sub><i>n</i></sub> (<b>1</b>), {[Zn(btmx)(L<sup>2</sup>)]·2H<sub>2</sub>O}<sub><i>n</i></sub> (<b>2</b>), {[Zn(btmx)(L<sup>3</sup>)]·1.5H<sub>2</sub>O}<sub><i>n</i></sub> (<b>3</b>), [Zn(btmx)(L<sup>4</sup>)]<sub><i>n</i></sub> (<b>4</b>), {[Zn<sub>4</sub>(btmx)<sub>3</sub>(L<sup>5</sup>)<sub>4</sub>(H<sub>2</sub>O)<sub>2</sub>]·4H<sub>2</sub>O}<sub><i>n</i></sub> (<b>5</b>), and [Zn(btmx)(H<sub>2</sub>L<sup>6</sup>)]<sub><i>n</i></sub> (<b>6</b>), have been obtained under similar
conditions (btmx = 1,4-bis(1,2,4-triazol-1-ylmethyl)-2,3,5,6-tetramethylbenzene,
H<sub>2</sub>L<sup>1</sup> = 1,3-benzenedicarboxylic acid, H<sub>2</sub>L<sup>2</sup> = 1,4-benzenedicarboxylic acid, H<sub>2</sub>L<sup>3</sup> = 1,3-adamantanedicarboxylic acid, H<sub>2</sub>L<sup>4</sup> <b>=</b> 1,3-adamantanediacetic acid, H<sub>2</sub>L<sup>5</sup> = 4,4′-oxidibenzoic acid, and H<sub>4</sub>L<sup>6</sup> =
3,3′,4,4′-benzophenone tetracarboxylic acid). The structure
determination reveals that complexes <b>1</b> and <b>4</b> are two-dimensional (2D) layered networks and exhibit typical (4,4)
topological nets. Complex <b>2</b> shows an undulating 2D (4,4)-network
with 2-fold interpenetration. Complex <b>3</b> possesses a three-dimensional
(3D) 3-fold interpenetrating 4-connected framework of 6<sup>6</sup>-<b>dia</b> topology. Both <b>5</b> and <b>6</b> have different 3D interpenetrated motifs generated by 2D →
3D interpenetration. Complex <b>5</b> belongs to a 3D framework
built from the interpenetration of 2D bilayers in an inclined mode,
while <b>6</b> involves a parallel interpenetration between
the adjacent 2D (4,4) layers. This work markedly indicates that the
effect of polycarboxylate ligands is significant in the construction
of these networks
Template-Assisted Synthesis of Co,Mn-MOFs with Magnetic Properties Based on Pyridinedicarboxylic Acid
To investigate the influence
of organic molecules with reactive functional groups as templates
on the structures of the resulting MOFs, four novel complexes based
on the pyridyl carboxylic acid ligand 5-(pyridin-4-yl)isophthalic
acid (H<sub>2</sub>pyip), namely, [Mn<sub>3</sub>(pyip)<sub>2</sub>(HCOO)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>]<sub><i>n</i></sub> (<b>1</b>), {[Co(pyip)(H<sub>2</sub>O)]·H<sub>2</sub>O}<sub><i>n</i></sub> (<b>2</b>), {[Mn<sub>2</sub>(pyip)<sub>2</sub>(H<sub>2</sub>O)<sub>4</sub>]·5H<sub>2</sub>O}<sub><i>n</i></sub> (<b>3</b>), and [Co(pyip)(EtOH)(H<sub>2</sub>O)]<sub><i>n</i></sub> (<b>4</b>), have been
synthesized under solvothermal conditions. In the presence of 4,4′-bipyridyl
as the template, 3D coordination framework <b>1</b> with the
Schläfli symbol of (4·6·7) (4<sup>2</sup>·5·6<sup>5</sup>·7<sup>3</sup>·8<sup>2</sup>·9·11) was
obtained. Using cyanoacetic acid as the template, we obtained 2D double-layered
structure <b>2</b> with the Schläfli symbol of (4<sup>3</sup>) (4<sup>6</sup>·6<sup>6</sup>·8<sup>3</sup>). <b>3</b> and <b>4</b> are prepared in the absence of a templating
agent. <b>3</b> features an infinite 2D network with a 1D water
chain penetrating the 1D channel and further results in a 3D supramolecule
through hydrogen-bond interactions. <b>4</b> contains two independent
2D networks that are further connected to a 2D double-layered supramolecular
framework by hydrogen bonds. The template-assisted method is a potential
approach for obtaining specific intriguing complexes that might be
difficult to access by routine synthetic methods. Magnetic investigations
revealed that both <b>1</b> and <b>2</b> exhibit weak
antiferromagnetic interactions mediated by pyip<sup>2–</sup>