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1.
Artigo em Inglês | MEDLINE | ID: mdl-33131271

RESUMO

Control of indoor CO2 concentration to a safe level is important to human health. Metal-organic-framework-based adsorbents show superior adsorption performance at moderate CO2 concentration compared to other solid adsorbents but suffer from low capacities and high regeneration temperature at indoor CO2 concentrations and poor humidity stability. Herein, we report epn-grafted Mg2(dobpdc) (epn = 1-ethylpropane-1,3-diamine) showing a CO2 capacity of 12.2 wt % at an acceptable concentration of 1000 ppm and a practically low desorption temperature of 70 °C, which surpasses the performance of conventional solid adsorbents under the given conditions. After poly(dimethylsiloxane) coating, this material reveals a significant adsorption amount (∼10 wt %) in humid conditions (up to 98% relative humidity) with structural durability.

2.
Artigo em Inglês | MEDLINE | ID: mdl-32969148

RESUMO

Although numerous porous adsorbents have been investigated for NH3 capture applications, these materials often exhibit insufficient NH3 uptake, low NH3 affinity at the ppm level, and poor chemical stability against wet NH3 conditions. The NH3 capture properties of M2 (dobpdc) complexes (M=Mg2+ , Mn2+ , Co2+ , Ni2+ , and Zn2+ ; dobpdc4- =4,4-dioxidobiphenyl-3,3-dicarboxylate) that contain open metal sites is presented. The NH3 uptake of Mg2 (dobpdc) at 298 K was 23.9 mmol g-1 at 1 bar and 8.25 mmol g-1 at 570 ppm, which are record high capacities at both pressures among existing porous adsorbents. The structural stability of Mg2 (dobpdc) upon exposure to wet NH3 was superior to that of the other M2 (dobpdc) and the frameworks tested. Overall, these results demonstrate that Mg2 (dobpdc) is a recyclable compound that exhibits significant NH3 affinity and capacity, making it a promising candidate for real-world NH3 -capture applications.

3.
Chem Commun (Camb) ; 56(7): 1038-1041, 2020 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-31850459

RESUMO

A crown ether-appended calix[2]triazolium[2]arene, which exhibits excellent selectivity for H2PO4- compared to other anions, has been designed and synthesized. The selectivity of the prepared receptor for H2PO4- is caused by the stabilization of H2PO4- by the neighboring triazolium hydrogen bond donors and crown ether hydrogen bond acceptors.

4.
Nanoscale ; 12(2): 1118-1127, 2020 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-31850427

RESUMO

Nanoparticles with an atomically ordered alloy phase have received enormous attention for application as catalysts in fuel cells because of their unique electronic properties resulting from unusually strong d-orbital interactions between two metal components. However, the synthesis of intermetallic nanoparticles requires a high reaction temperature, thus necessitating the protection of nanoparticles with inorganic layers to prevent aggregation of nanoparticles during synthesis. The protective layer needs to be removed later for application as a catalyst, which is a cumbersome process. Herein, a novel synthetic strategy is reported for the preparation of L10-PtZn intermetallic nanoparticles by utilizing Pt2+-exchanged ZIF-8 nanocubes as a solid-state precursor. The Pt2+-exchanged ZIF-8 phase plays a dual role as a metal ion source for L10-PtZn nanoparticles and as a carbonaceous matrix that restrains the aggregation of nanoparticles during thermal treatment. The L10-PtZn nanoparticles embedded in a hollow carbon nanocage obtained from one-step annealing of Pt2+-exchanged ZIF-8 showed better electrocatalytic activity and durability toward methanol oxidation under acidic electrolyte conditions than those obtained from commercial Pt/C catalysts.

5.
Chemistry ; 2019 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-31873958

RESUMO

Two new heterometallic metal-organic frameworks (MOFs), LnZnTPO 1 and 2, and two homometallic MOFs, LnTPO 3 and 4 (Ln=Eu for 1 and 3, and Tb for 2 and 4; H3 TPO=tris(4-carboxyphenyl)phosphine oxide) were synthesized, and their structures and properties were analyzed. They were prepared by solvothermal reaction of the C3 -symmetric ligand H3 TPO with the corresponding metal ion(s) (a mixture of Ln3+ and Zn2+ for 1 and 2, and Ln3+ alone for 3 and 4). Single-crystal XRD (SXRD) analysis revealed that 1 and 3 are isostructural to 2 and 4, respectively. TGA showed that the framework is thermally stable up to about 400 °C for 1 and 2, and about 450 °C for 3 and 4. PXRD analysis showed their pore-structure distortions without noticeable framework-structure changes during drying processes. The shapes of gas sorption isotherms for 1 and 3 are almost identical to those for 2 and 4, respectively. Solvothermal immersion of 1 and 2 in Tb3+ and Eu3+ solutions resulted in the framework metal-ion exchange affording 4 and 3, respectively, as confirmed by photoluminescence (PL), PXRD, IR, inductively coupled plasma atomic emission spectroscopy (ICP-AES), and energy-dispersive X-ray (EDX) analyses.

6.
Inorg Chem ; 58(20): 14107-14111, 2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31596572

RESUMO

While mixed-metal ions into a single framework can be randomly arranged in most reported cases, it is synthetically challenging to control and organize the distribution of different metal ions over a three-dimensional structure. In this context, for the family of M2(dobpdc) with broad applications, we present the first case of a bimetallic Mg/Zn(dobpdc) framework with a 1:1 compositional ratio, based on a one-dimensional Zn(H2dobpdc) template, which would not be obtained by the conventional reaction of the corresponding metal salts. Moreover, we demonstrate that the resultant compositional ratios in the bimetallic M'/Zn(dobpdc) (M' = Mg, Mn, Co, Ni) are governed by the ionic radii of the metals and the affinity of the metal ions for the linker groups. Notably, the unexpected gradual reduction in the adsorption enthalpy and the mixed CO2 adsorption feature are revealed in Mg/Zn(dobpdc) and its diamine-grafted framework, respectively.

7.
Angew Chem Int Ed Engl ; 58(45): 16152-16155, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31502347

RESUMO

An S-shaped gas isotherm pattern displays high working capacity in pressure-swing adsorption cycle, as established for CO2 , CH4 , acetylene, and CO. However, to our knowledge, this type of adsorption behavior has not been revealed for NH3 gas. Herein, we design and characterize a hydrogen-bonded organic framework (HOF) that can adsorb NH3 uniquely in an S-shape (type IV) fashion. While conventional porous materials, mostly with type I NH3 adsorption behavior, require relatively high regeneration temperature, this platform which has significant working capacity is easily regenerated and recyclable at room temperature.

8.
Chem Commun (Camb) ; 55(65): 9713-9716, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31353388

RESUMO

Single-crystal-to-single crystal structural conversions occur in a Zn(ii) coordination polymer, uniquely induced by fine-tuned relative humidity. Proton conductivity depends on the number of hydrogen bonds in the structures. Slope change in the Arrhenius plot is uncommon among coordination-based conductors and associated with temperature-dependent phase changes.

9.
Chem Sci ; 10(9): 2663-2669, 2019 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-30996982

RESUMO

Elaborate control of wettability in a single platform is essential for materials' applications towards oil-water separation, but it still remains challenging. Herein, we performed postcoordination modification of Mg2(dobpdc) with monoamines of various alkyl chain lengths, enabling both long-term hydrolytic stability and facile fine-tuning of wettability. An efficient separation of oil-water mixtures was achieved by using the octylamine-appended framework (OctA). We also prepared an OctA/reduced graphene oxide aerogel that showed exceptional absorption capacities towards organic solvents and oil as well as superb recyclability with maintained absorbency.

10.
Dalton Trans ; 48(7): 2263-2270, 2019 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-30693920

RESUMO

Post-synthetic methods are considered facile and effective for adjusting a material's properties. This Frontiers article highlights recent advances in the post-synthetic modifications of MOF-74 type frameworks, whose high-density exposed metal sites, arranged along the chain direction, are grafted by various diamines with different lengths and structures, leading to the tuning of CO2 adsorption capabilities.

11.
ACS Appl Mater Interfaces ; 10(47): 40372-40377, 2018 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-30411880

RESUMO

Distinguishing specific molecules from similar chemical species with minor structural differences is challenging, and differentiation has typically been based on analyte-dependent host-guest interactions upon irradiation with a single wavelength. In this study, we prepared a Cd-based metal-organic framework exhibiting nearly constant emission intensity over a wide range of excitations. Because of its unique emission characteristics, this material facilitated the differentiation of specific molecules amidst structurally similar chemical species via competitive absorption. Such discriminative identification was uniquely achieved based on the use of different excitation wavelengths and is demonstrated to be applicable to the recognition of a target analyte in sensory applications.

12.
Chem Sci ; 9(33): 6871-6877, 2018 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-30310620

RESUMO

A hypercrosslinked porous organic polymer was modified by post-oxidation and post-sulfonation to obtain a porous platform with a high density of acidic groups. Such an acidified material exhibits record high NH3 adsorption capacity per surface area, fast adsorption rate, and recyclability at low desorption temperature. Noticeably, the coating of the polymer with PDMS represents a facile and efficient route to enable both a significant improvement of low-pressure NH3 adsorption capacity (∼40-fold enhancement; from 0.04 to 1.41 mmol g-1) with respect to the non-modified polymer at 500 ppm and hydrophobicity associated with the selective sorption of NH3 over water vapor (hydrophilic for the non-coated material). This material is easy to prepare, cost-effective, and scalable to mass production.

13.
Acta Crystallogr E Crystallogr Commun ; 74(Pt 8): 1107-1110, 2018 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-30116572

RESUMO

The asymmetric unit of the solvated title complex, [Ir(C11H8N)2(C15H14NO3)]·2CH2Cl2, consists of two complex mol-ecules together with four di-chloro-methane solvent mol-ecules, one of which is disordered. In each complex mol-ecule, the IrIII ion has a distorted octa-hedral coordination environment defined by two 2-phenyl-pyridine ligands, through two phenyl C and two pyridine N atoms, and by one N,O-bidentate 2-[(2,4-di-meth-oxy-phenyl-imino)-meth-yl]phenolate anion. The IrIII ions lie almost in the equatorial planes with deviations of 0.0396 (17) and 0.0237 (17) Å, respectively, for the two complex mol-ecules. In both complex mol-ecules, the two 2-phenyl-pyridine ligands are nearly perpendicular to each other [dihedral angles between the least-squares-planes of 89.91 (11) and 85.13 (11)°]. In the crystal, inter-molecular C-H⋯O inter-actions as well as inter-molecular C-H⋯π inter-actions are present, leading to a three-dimensional network structure. One of the four dichlormethane solvent mol-ecules shows disorder over two sets of sites [occupancy ratio 0.79 (2):0.21 (2)].

14.
ChemSusChem ; 11(10): 1694-1707, 2018 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-29603670

RESUMO

For real-world postcombustion applications in the mitigation of CO2 emissions using dry sorbents, adsorption and desorption behaviors should be controlled to design and fabricate prospective materials with optimal CO2 performances. Herein, we prepared diamine-functionalized Mg2 (dobpdc) (H4 dobpdc=4,4'-dihydroxy-(1,1'-biphenyl)-3,3'-dicarboxylic acid). (1-diamine) with ethylenediamine (en), primary-secondary (N-ethylethylenediamine-een and N-isopropylethylenediamine-ipen), primary-tertiary, and secondary-secondary diamines. A slight alteration of the number of alkyl substituents on the diamines and their alkyl chain length dictates the desorption temperature (Tdes ) at 100 % CO2 , desorption characteristics, and ΔT systematically to result in the tuning of the working capacity. The existence of bulky substituents on the diamines improves the framework stability upon exposure to O2 , SO2 , and water vapor, relevant to real flue-gas conditions. Bulky substituents are also responsible for an interesting two-step behavior observed for the ipen case, as revealed by DFT calculations. Among the diamine-appended metal-organic frameworks, 1-een, which has the required adsorption and desorption properties, is a promising material for sorbent-based CO2 capture processes. Hence, CO2 performance and framework durability can be tailored by the judicial selection of the diamine structure, which enables property design at will and facilitates the development of desirable CO2 -capture materials.

15.
Sci Rep ; 8(1): 4661, 2018 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-29549304

RESUMO

Two dimensional layered organic-inorganic halide perovskites offer a wide variety of novel functionality such as solar cell and optoelectronics and magnetism. Self-assembly of these materials using solution process (ex. spin coating) makes crystalline thin films synthesized at ambient environment. However, flexibility of organic layer also poses a structure stability issue in perovskite thin films against environment factors (ex. moisture). In this study, we investigate the effect of solvents and moisture on structure and property in the (C6H5(CH2)2NH3)2(Cu, Mn)Cl4 (Cu-PEA, Mn-PEA) perovskite thin films spin-coated on Si wafer using three solvents (H2O, MeOH, MeOH + H2O). A combination of x-ray diffraction (XRD) and x-ray absorption spectroscopy (XAS) show that relative humidity (RH) has a profound effect on perovskite thin films during sample synthesis and storage, depending on the kind of solvent used. The ones prepared using water (Cu-PEA:H2O, Mn-PEA:H2O) show quite different behavior from the other cases. According to time-dependent XRD, reversible crystalline-amorphous transition takes place depending on RH in the former cases, whereas the latter cases relatively remain stable. It also turns out from XAS that Mn-PEA thin films prepared with solvents such as MeOH and MeOH + H2O are disordered to the depth of about 4 nm from surface.

16.
Dalton Trans ; 47(3): 845-851, 2018 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-29250623

RESUMO

MII (M = Mn, Ni) coordination frameworks, singly linked by end-on azide ligands, were prepared by employing the long, flexible spacer ligand, p-XBP4. These two-dimensional layer structures underwent reversible crystal-to-amorphous phase transformations during the hydration-dehydration process. Moreover, the magnetic nature changes from antiferromagnetic to ferromagnetic coupling when moving from Mn to Ni.

17.
Inorg Chem ; 56(13): 7443-7448, 2017 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-28617591

RESUMO

Three MOF-74-type Co(II) frameworks with one-dimensional hexagonal channels have been prepared. Co(II) spins in a chain are ferromagnetically coupled through carboxylate and phenoxide bridges. Interchain antiferromagnetic couplings via aromatic ring pathways operate over a Co-Co length shorter than ∼10.9 Å, resulting in a field-induced metamagnetic transition, while being absent over lengths longer than ∼14.7 Å.

18.
Inorg Chem ; 56(9): 4911-4917, 2017 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-28414438

RESUMO

Controlling the coordination sphere of lanthanoid complexes is a challenging critical step toward controlling their relaxation properties. Here we present the synthesis of hexacoordinated dysprosium single-molecule magnets, where tripodal ligands achieve a near-perfect octahedral coordination. We perform a complete experimental and theoretical investigation of their magnetic properties, including a full single-crystal magnetic anisotropy analysis. The combination of electrostatic and crystal-field computational tools (SIMPRE and CONDON codes) allows us to explain the static behavior of these systems in detail.

19.
Inorg Chem ; 56(1): 305-312, 2017 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-27936739

RESUMO

Five-fold interpenetrated Zn(II) frameworks (1 and 2) have been prepared, and an irreversible phase transformation from 1 to 2 is found to occur through a dissolution-recrystallization process. Compound 1 exhibits the highest quenching efficiency (>96%) for nitrobenzene at 7 ppm among luminescent coordination polymers. Selective discrimination of nitroaromatic molecules including o-nitrophenol (o-NP), p-nitrophenol (p-NP), 2,4-dinitrophenol (DNP), and 2,4,6-trinitrophenol (TNP) is realized in 1 and 2 as a result of the fact that the framework-analyte interaction affords characteristic emission signals. This observation is the first case of a nonporous coordination framework for such discriminative detection. Notably, significant hydrophobicity is evident in the framework 1 because of its surface roughness, which accounts for the enhanced quenching ability.

20.
ChemSusChem ; 10(3): 541-550, 2017 02 08.
Artigo em Inglês | MEDLINE | ID: mdl-28004886

RESUMO

A combined sonication and microwave irradiation procedure provides the most effective functionalization of ethylenediamine (en) and branched primary diamines of 1-methylethylenediamine (men) and 1,1-dimethylethylenediamine (den) onto the open metal sites of Mg2 (dobpdc) (1). The CO2 capacities of the advanced adsorbents 1-en and 1-men under simulated flue gas conditions are 19 wt % and 17.4 wt %, respectively, which are the highest values reported among amine-functionalized metal-organic frameworks (MOFs) to date. Moreover, 1-den exhibits both a significant working capacity (12.2 wt %) and superb CO2 uptake (11 wt %) at 3 % CO2 . Additionally, this framework showcases the superior recyclability; ultrahigh stability after exposure to O2 , moisture, and SO2 ; and exceptional CO2 adsorption capacity under humid conditions, which are unprecedented among MOFs. We also elucidate that the performance of CO2 adsorption can be controlled by the structure of the diamine ligands grafted such as the number of amine end groups or the presence of side groups, which provides the first systematic and comprehensive demonstration of fine-tuning of CO2 uptake capability using different amines.


Assuntos
Dióxido de Carbono/química , Diaminas/química , Compostos Organometálicos/química , Adsorção , Dióxido de Carbono/isolamento & purificação , Modelos Moleculares , Conformação Molecular , Oxigênio/química , Teoria Quântica , Vapor , Dióxido de Enxofre/química , Temperatura
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