Showing papers in "Dalton Transactions in 2019"
TL;DR: The robust electrochemical properties indicate the composites as promising electrodes for electrochemical energy storage devices.
Abstract: Nanocomposites with a well-defined sandwich-like nanostructure were prepared via in situ growing NiCo-layered double hydroxide nanosheets with tunable Ni/Co ratios on reduced graphene oxide (rGO). Electrochemical impedance spectra and N2 adsorption/desorption isotherms confirmed that these sandwich nanostructures effectively promoted charge transport and enlarged the specific surface area. The nanocomposites with Ni : Co = 2 : 1 exhibited a maximum specific capacitance of 2130 F g−1 at 2 A g−1, excellent rate capability (72.7% retention at 15 A g−1), and cycling stability. Asymmetric supercapacitors were assembled with these nanocomposite cathodes and rGO as a negative electrode (anode), and demonstrated an energy density of 34.5 W h kg−1 at a power density of 772 W kg−1, while maintaining a capacity retention of 86.7% after 10 000 cycles at 5 A g−1. The robust electrochemical properties indicate the composites as promising electrodes for electrochemical energy storage devices.
218 citations
TL;DR: An in-depth survey of synthetic approaches and surface modifications of SPIONs is provided along with their biological applications such as targeting, site-specific drug delivery and therapy.
Abstract: Cancer is a global epidemic and is considered a leading cause of death. Various cancer treatments such as chemotherapy, surgery, and radiotherapy are available for the cure but those are generally associated with poor long-term survival rates. Consequently, more advanced and selective methods that have better outcomes, fewer side effects, and high efficacies are highly in demand. Among these is the use of superparamagnetic iron oxide nanoparticles (SPIONs) which act as an innovative kit for battling cancer. Low cost, magnetic properties and toxicity properties enable SPIONs to be widely utilized in biomedical applications. For example, magnetite and maghemite (Fe3O4 and γ-Fe2O3) exhibit superparamagnetic properties and are widely used in drug delivery, diagnosis, and therapy. These materials are termed SPIONs when their size is smaller than 20 nm. This review article aims to provide a brief introduction on SPIONs, focusing on their fundamental magnetism and biological applications. The quality and surface chemistry of SPIONs are crucial in biomedical applications; therefore an in-depth survey of synthetic approaches and surface modifications of SPIONs is provided along with their biological applications such as targeting, site-specific drug delivery and therapy.
148 citations
TL;DR: It was found that compound 1 could not only detect trivalent Fe3+, Cr3+ and Al3+ ions with high selectivity and recyclability but also serve as an excellent selective sensing material for PO43- ions among some anions.
Abstract: A luminescent Eu-MOF, namely, [Eu2(ppda)2(npdc)(H2O)]·H2O (1) based on the mixed ligands 4-(pyridin-3-yloxy)-phthalic acid (H2ppda) and naphthalene-1,4-dicarboxylic acid (H2npdc) was synthesized under solvothermal conditions. Compound 1 was initially constructed from the 1D binuclear chains of [Ln(npdc)]2 and further connected by ppda2- ligands, forming a 2D layered structure. It is worth noting that compound 1 exhibited excellent fluorescence stability in the pH range of 2-13 in an aqueous solution. It was found that compound 1 could not only detect trivalent Fe3+, Cr3+ and Al3+ ions with high selectivity and recyclability but also serve as an excellent selective sensing material for PO43- ions among some anions. The detection of NACs demonstrated that compound 1 could also behave as a functional probe with high selectivity, sensitivity, and recyclability, and the detection limit of TNP was 2.97 × 10-6 M. Furthermore, the luminescent sensing mechanisms for different analytes were speculated.
131 citations
TL;DR: A thin layer of conductive polyaniline (PANI) was decorated on Ni foam (NF) before the growth of Ni-MOF to tackle the issues of low conductivity and poor stability, which results in an asymmetric supercapacitor device outperforming most of the reported pristine MOF-based ASC devices.
Abstract: Metal–organic frameworks (MOFs) have emerged as promising electrode materials for supercapacitors (SCs), due to their diverse functionalities and high porosity. However, the applications of MOFs in practical SC devices are restricted by their intrinsic low conductivity and poor stability. Herein, a thin layer of conductive polyaniline (PANI) was decorated on Ni foam (NF) before the growth of Ni-MOF to tackle these issues. PANI not only improves the conductivity but also promotes the formation of Ni-MOF nanosheet arrays and ensures good mechanical adhesion. The as-prepared Ni-MOF/PANI/NF exhibits a high areal capacitance (3626.4 mF cm−2 at 2 mA cm−2) and good rate capacity (71.3% at 50 mA cm−2). Moreover, an asymmetric supercapacitor (ASC) device using Ni-MOF/PANI/NF and activated carbon (AC) can deliver a maximum energy density of 45.6 W h kg−1 (850.0 W kg−1) with excellent cycling stability (capacitance retention of 81.6% after 10 000 cycles), outperforming most of the reported pristine MOF-based ASC devices.
109 citations
TL;DR: The outstanding volumetric electrochemical performance and energy density of the ASC based on the flexible Ti3C2Tx/P-100-H hybrid film electrode demonstrated its promising potential as a strong power source for small portable and wearable electronic devices.
Abstract: MXenes are two-dimensional transition metal carbides/nitrides, and they have shown exciting application prospects for electrochemical energy storage in the future owing to their hydrophilicity, metallic conductivity and surface redox reactions, which are crucial for high-capacitance and high-rate electrode materials. However, the strong tendency of adjacent MXene flakes to aggregate or self-restack under the van der Waals force limits the electrochemical performance of MXene-based electrodes for practical applications. In this study, we developed a simple and effective method to prepare Ti3C2Tx/PEDOT:PSS hybrid films via filtering the Ti3C2Tx/Clevios PH1000 compound inks, followed by H2SO4 treatment. H2SO4 treatment could remove part of the insulating PSS from the Ti3C2Tx/PEDOT:PSS hybrid film, resulting in significant conductivity enhancement of the composite. Furthermore, the conductive PEDOT not only acted as a pillar between Ti3C2Tx sheets to expose more electroactive surfaces and reduce ion diffusion pathways but also played a role as a conductive bridge to form multidimensional electronic transport channels for accelerating the electrochemical reaction process. As a result, the as-prepared H2SO4-treated Ti3C2Tx/PEDOT:PSS (Ti3C2Tx/P-100-H) hybrid film exhibited 4.5-fold increase in the specific surface area and high volumetric capacitance of 1065 F cm-3 at 2 mV s-1 with superior rate performance in 1 M H2SO4 electrolyte. Especially, we assembled an asymmetric supercapacitor (ASC) with excellent flexibility based on a Ti3C2Tx/P-100-H hybrid negative electrode and rGO film positive electrode, which delivered high energy density of 23 mW h cm-3 and high power density of 7659 mW cm-3. Moreover, a simple luminous band was designed and powered by our two ASCs in series. The outstanding volumetric electrochemical performance and energy density of the ASC based on the flexible Ti3C2Tx/P-100-H hybrid film electrode demonstrated its promising potential as a strong power source for small portable and wearable electronic devices.
104 citations
TL;DR: This perspective focuses on various types of novel cisplatin-based Pt(iv) complexes, including Pt-loaded nanostructures, to overcome cisPlatin resistance and special attention will be devoted to complexes that target the tumor microenvironment, which is a new area for the development of effective Pt(IV) prodrugs.
Abstract: Cisplatin plays a pivotal role in the treatment of various malignant tumors, but its therapeutic effects are hampered by drug resistance. Pt(iv) prodrugs represent a promising class of "non-conventional" platinum-based anticancer agents to circumvent drug resistance, which can be easily functionalized with other bioactive ligands. One strategy is to build "dual-action" and "multi-action" Pt(iv) prodrugs that not only damage DNA but also perturb other pathways related to cisplatin resistance to achieve combinatorial therapeutic effects. Another way to overcome the shortcomings of cisplatin is to deliver Pt(iv) prodrugs via nanocarriers. Most studies in this area have focused on designing prodrugs based on the mechanism of cisplatin resistance within isolated cancer cells. Recent findings, however, reveal that the tumor microenvironment also plays important roles in the development of cisplatin resistance. This perspective focuses on various types of novel cisplatin-based Pt(iv) complexes, including Pt-loaded nanostructures, to overcome cisplatin resistance. Special attention will be devoted to complexes that target the tumor microenvironment, which is a new area for the development of effective Pt(iv) prodrugs. Our summary and outlook may have a hope to help researchers in the field generate new ideas and strategies to develop more potent Pt(iv) prodrugs to combat cisplatin resistance.
103 citations
TL;DR: The synthesis of a Co-containing metal-organic framework (Co-MOF) is presented and its electrocatalytic application towards the oxygen electrocatalysis and it is believed that the as-developed Co- MOF holds the potential to be used as both a cathode and an anode electrocatalyst in the future energy storage and conversion systems.
Abstract: The oxygen electrocatalysis, i.e. the oxygen reduction and evolution reactions, is traditionally executed using noble metal and metal oxide-based nanostructures. However, they are associated with many disadvantages such as high cost, lower durability/selectivity and detrimental environmental effects; this motivates researchers to develop new electroactive materials. In this study, we presented the synthesis of a Co-containing metal-organic framework (Co-MOF) and explored its electrocatalytic application towards the oxygen electrocatalysis (i.e. the oxygen reduction reaction and oxygen evolution reaction). The Co-MOF efficiently catalyzes the ORR with a lower onset (0.85 V vs. RHE)/reduction potential and higher reduction current density by a four-electron reduction path. Moreover, the MOF shows higher durability with >70% performance retention after 25 hours of reaction and tolerance towards methanol; this demonstrates its potential for application in direct methanol fuel cells (DMFCs); furthermore, due to the availability of more active sites and accessible surface area, the Co-MOF performs well towards the OER with lower onset potential and small Tafel slope as compared to the commercial RuO2 nanoparticles. Moreover, it needs only 280 mV overpotential to deliver the state-of-the-art current density of 10 mA cm-2 and robust stability. It shows the high TOF value of 93.21 s-1 at the overpotential of 350 mV as compared to the reported MOF/nanoparticle-based electrocatalysts and the state-of-the-art RuO2. Therefore, we believe that the as-developed Co-MOF holds the potential to be used as both a cathode and an anode electrocatalyst in the future energy storage and conversion systems.
96 citations
TL;DR: This work represents the first carbazole-functionalized metal-organic framework as a fluorescent sensor for the highly efficient detection of antibiotics, pesticides and nitroaromatic compounds.
Abstract: Organic pollutants, such as antibiotics, pesticides, and nitroaromatic compounds (NACs), have posed a great threat to human health and sustainable development. Therefore, the detection of these organic pollutants is of great importance but challenging. In this work, we synthesized a rigid conjugated tricarboxylic acid ligand 4,4'-(9-(4'-carboxy-[1,1'-biphenyl]-4-yl)-9H-carbazole-3,6-diyl)dibenzoic acid (H3CBCD), and employed this ligand to react with Cd(ii) ions to construct a Cd-LMOF, namely [Cd3(CBCD)2(DMA)4(H2O)2]·10DMA (Cd-CBCD). Cd-CBCD features a three-dimensional (3D) supramolecular framework based on two-dimensional (2D) layer structures through ππ stacking interactions. The fluorescence sensing measurements demonstrate that Cd-CBCD can detect nitrofurans (NFs), 4-nitroaniline (4-NA) and 2,6-dichloro-4-nitroaniline (DCN) with high selectivity and sensitivity. This work represents the first carbazole-functionalized metal-organic framework as a fluorescent sensor for the highly efficient detection of antibiotics, pesticides and nitroaromatic compounds.
93 citations
TL;DR: The synergistic effects of the core-shell CoMoO4@NiCo2S4@NF electrode material highlight the potential of this composite as an effective active material for supercapacitor applications.
Abstract: Supercapacitors are one of the most promising renewable-energy storage systems. In this study, a three-dimensional walking palm-like core–shell CoMoO4@NiCo2S4@nickel foam (NF) nanostructure was synthesized using a two-step hydrothermal method for high electrochemical performance. The as-prepared composite exhibited a high areal capacitance of 17.0 F cm−2 (2433 F g−1) at a current density of 5 mA cm−2 in a three-electrode system. The results revealed outstanding cycling stability of 114% after 10 000 charge–discharge cycles. An aqueous asymmetric supercapacitor device assembled with CoMoO4@NiCo2S4@NF and activated carbon (AC)@NF as the positive and negative electrodes, respectively, showed a high capacitance of 4.19 F cm−2 (182 F g−1) and delivered a high energy density of 60.2 W h kg−1 at a power density of 188 W kg−1 and a high power density of 1.5 kW kg−1 at an energy density 29.2 W h kg−1, lighting 22 parallel-connected red light emitting diodes for over 60 s. The synergistic effects of the core–shell CoMoO4@NiCo2S4@NF electrode material highlight the potential of this composite as an effective active material for supercapacitor applications.
93 citations
TL;DR: This review article is aimed at updating researchers on the recent developments on the synthesis and evaluation of ferrocene-containing bio-active pharmacophores with emphasis on their structure-activity relationship and mechanism of action.
Abstract: Two exemplary contributions of organometallics in medicinal chemistry, ferroquine and ferrocifen, which exhibit excellent anti-plasmodial and anti-cancer activities, respectively, have opened a new field called medicinal organometallic chemistry. This field has been gaining significant interest due to the recent upsurge in ferrocene-linked organic frameworks with promising biological potential. The success of ferrocene is due to the sustained efforts by organic medicinal chemists and its inherent stability in air, heat and light, low toxicity, low cost and reversible redox properties. The replacement of the aryl/heteroaryl core with a ferrocene nucleus in organic molecules imparts a significant change not only in their molecular properties, such as solubility and hydro-/lipophilicity, but also improves the activities of bioactive compounds. Ferrocifen (ferrocene analogue of hydroxytamoxifen) possesses the remarkable feature of being anti-proliferative against both the MCF-7 (hormone dependent) and MDA-MB-231 (hormone independent) breast cancer cell lines. Accordingly, this review article is aimed at updating researchers on the recent developments (2014-18) on the synthesis and evaluation of ferrocene-containing bio-active pharmacophores with emphasis on their structure-activity relationship and mechanism of action.
92 citations
TL;DR: Investigations on the solid-state fluorescence properties show that the clusters 2, 3, 5 and 6 display the characteristic lanthanum luminescence at room temperature and magnetic studies reveal that weak antiferromagnetic interactions exist between adjacent Gd(iii) ions in cluster 4.
Abstract: Herein, ten new linear-shaped LnIII4 and LnIII6 clusters, with the formula [Ln4(acac)6L2(CH3O)2(CH3OH)4]·xCH3OH (Ln = Nd (1), Sm (2), Eu (3), Gd (4), Tb (5), Dy (6), and Tm (8), Hacac = acetylacetone), [Ln6(acac)4L4(CH3O)6]·xCH3OH (Er (7) and Yb (9)), and [Lu4(acac)6L2(OH)2]·2CH2Cl2 (10), based on a polydentate Schiff base ligand, H2L, and a β-diketone co-ligand were successfully synthesized and structurally characterized. Single crystal X-ray diffraction measurements reveal that the structures of the clusters 1–6, 8 and 10 are very similar and their central Ln(III) ions are linearly arranged Ln4; however, the clusters 7 and 9 possess a rare linearly arranged Ln6. The investigations on the solid-state fluorescence properties show that the clusters 2, 3, 5 and 6 display the characteristic lanthanum luminescence at room temperature. Magnetic studies reveal that weak antiferromagnetic interactions exist between adjacent Gd(III) ions in cluster 4. More importantly, the cluster 4 exhibits significant MCE with the maximum −ΔSm value of 27.96 J kg−1 K−1 at 2.0 K and 7.0 T, whereas the cluster 6 displays a slow magnetic relaxation behavior under a zero dc field with the effective energy barrier ΔE/kB = 8.64 K and τ0 = 6.98 × 10−6 s.
TL;DR: The presented MOF exhibits excellent selectivity toward cationic methylene blue (MB) dye adsorption and its separation over neutral (neutral red) and anionic (methyl orange) dyes, and simultaneous one-pot photocatalytic reduction of Cr(vi) and dye degradation has been demonstrated with high efficiency using the same catalyst.
Abstract: A Cd(ii)-based metal-organic framework (MOF) {[Cd(PA)(4,4'-bpy)2](H2O)}n (where, PA = pamoic acid, and bpy = bipyridine) has been demonstrated to have trifunctional properties, namely as (i) an efficient and selective adsorbent for dyes, (ii) a visible-light-active photocatalyst for the degradation of dyes and (iii) a photocatalyst for Cr(vi) reduction. Hence, this material has a very good potential for application in environmental remediation. In particular, the MOF exhibits excellent selectivity toward cationic methylene blue (MB) dye adsorption and its separation over neutral (neutral red) and anionic (methyl orange) dyes. In addition, the catalyst has also been explored for the photocatalytic degradation of less adsorbed dyes, such as methyl orange (MO) and rhodamine B (RhB). Subsequently, the potential of the presented MOF for the photocatalytic reduction of Cr(vi) under visible light irradiation has also been investigated and the catalyst was found to reduce 95% of Cr(vi) within 3 h. Moreover, simultaneous one-pot photocatalytic reduction of Cr(vi) and dye degradation has been demonstrated with high efficiency using the same catalyst. The mechanism of adsorption could be correlated to the presence of peripheral hydroxyl groups in the MOF and the photocatalytic activity observed under visible light could be attributed to the optical properties of Cd-MOF. In principle, this work could broaden the utilization of single metal organic platform for multifunctional applications toward environmental remediation.
TL;DR: This work not only deepens the understanding of the improved HER performance of surface intercalated catalysts, but also provides novel strategies for preparing durable electrocatalysts through surface engineering.
Abstract: An efficient hydrogen evolution reaction (HER) depends essentially on high-performing electrocatalysts. The aggregation of catalysts normally deteriorates their activity and stability. In this study, a two-step route was used to synthesize surface intercalated well-dispersed spherical MoS2xSe2(1−x) nanocatalysts. The resulting catalysts present a highly active and stable performance towards the HER with an overpotential of −143 mV at 10 mA cm−2, and a Tafel slope of 53.8 mV dec−1. The mechanism for the enhanced HER was analyzed and was attributed to three factors: (i) large numbers of defects and edge active sites arising from the coexistence of S and Se elements; (ii) enhanced electric conductivity arising from the phase transition from the semiconducting 2H-phase to metallic 1T-phase during the intercalation process; and (iii) enlarged contact areas between active sites and electrolyte caused by the increased surface roughness due to the surface intercalation. This work not only deepens our understanding of the improved HER performance of surface intercalated catalysts, but also provides novel strategies for preparing durable electrocatalysts through surface engineering.
TL;DR: This MOF shows ratiometric detection of acetone, Cr2O72- ions, and nitroaromatic compounds (NACs) and is the first LnIII-MOF which can display distinguishing fluorescence phenomena on NACs rather than relying on the quenching effect.
Abstract: A water-stable EuIII-based metal–organic framework (MOF) with dual-emission luminescence behavior, namely {[Eu4(INO)5(μ3-OH)2Cl4(H2O)]·(NO3)·(H2O)5}n (Eu-MOF; HINO = isonicotinic acid N-oxide), was successfully constructed by the solvothermal reaction of Eu3+ ions with the organic ligand HINO. The cationic 3D framework contains microporous channels with accessible Lewis-base sites and NO3− ions as balanced anions, which all contribute to the selective detection of multifarious analytes. This MOF shows ratiometric detection of acetone, Cr2O72− ions, and nitroaromatic compounds (NACs). In particular, it shows great recognition of four NACs in water, representing the first LnIII-MOF which can display distinguishing fluorescence phenomena on NACs rather than relying on the quenching effect. Furthermore, this is also the first example of a MOF-sensor for detecting these explosives discriminatively by ratiometric methods. Additionally, the mechanisms for luminescent responses towards different analytes have been discussed in detail.
TL;DR: These interesting results indicate that heteromatallic coordination polymers can serve as favorable dual- or even multiple-responsive luminescence sensors to selectively recognize different kinds of contaminants.
Abstract: The detection of nitrofuran antibiotics and toxic inorganic anions is currently necessary and challenging because their abuse and/or residuals have caused severe environmental pollution and illness. A heterometallic two-dimensional (2D) layered complex, {[Eu2Na(Hpddb)(pddb)2(CH3COO)2]·2.5(DMA)}n (1), was solvothermally synthesized and structurally and photophysically characterized. Pairs of acetate aggregated {Eu2Na(CH3COO)2} chains are periodically interconnected by V-shaped 4,4'-(pyridine-2,6-diyl)dibenzolate (pddb) linkers. More interestingly, the layered complex exhibits a bright red emission and can efficiently discriminate nitrofuran antibiotics by luminescent quenching with a strong quenching constant (Ksv) and low detection limit (LOD) of 4.93 × 104 M-1 and 0.64 μM for nitrofurazone, 4.42 × 104 M-1 and 0.68 μM for nitrofurantoin as well as 2.13 × 104 M-1 and 1.06 μM for furazolidone. Additionally, 1 can also probe trace amounts of toxic Cr2O72- and MnO4- anions with Ksv = 6.45 × 103 M-1 and LOD = 5.35 μM for Cr2O72- and Ksv = 2.84 × 103 M-1 and LOD = 5.99 μM for MnO4- anions. These interesting results indicate that heteromatallic coordination polymers can serve as favorable dual- or even multiple-responsive luminescence sensors to selectively recognize different kinds of contaminants.
TL;DR: The Mn-CP exhibits high photoelectron response performance while Zn-CP can generate frequency tunable alternating current when the period of on-off illumination is changed.
Abstract: Room temperature phosphorescence of Mn(II) and Zn(II) based coordination polymers (Mn-CP and Zn-CP) with a different mechanism was confirmed by experiments and theory calculations. The Mn-CP exhibits high photoelectron response performance while Zn-CP can generate frequency tunable alternating current when the period of on–off illumination is changed.
TL;DR: A highly water-stable MOF-based magnetic material Fe3O4@ZTB-1 has been obtained and it was for the first time used as an excellent adsorbent for the fast adsorption of Congo red from aqueous solutions, exhibiting an adsorptive capacity of 458 mg CR per gram.
Abstract: Metal–organic frameworks (MOFs) are an exciting class of porous crystallized materials, which have attracted great interest in sustainable energy and environmental remediation. Magnetite (Fe3O4) is one of the best-known magnetic materials and has been extensively studied with respect to properties involving high saturation magnetization, biocompatibility and low toxicity. The combination of MOFs and Fe3O4 has shown its potential applications in drug delivery, catalysis and wastewater treatment. However, only classical porous MOFs are used to encapsulate magnetic nanoparticles, such as MIL-100(Fe), ZIF-8, UiO-66 and so on. Herein, we firstly synthesized a new MOF ZTB-1 and surveyed its applications in magnetic materials. As a result, a highly water-stable MOF-based magnetic material Fe3O4@ZTB-1 has been obtained, and it was for the first time used as an excellent adsorbent for the fast adsorption of Congo red (CR) from aqueous solutions, exhibiting an adsorption capacity of 458 mg CR per gram. The electrostatic interactions and hydrogen bond are responsible for binding of CR with Fe3O4@ZTB-1. The magnetic material Fe3O4@ZTB-1 shows a potential application in dyeing wastewater treatment.
TL;DR: Two luminescent coordination polymers reveal readily dispersible two-dimensional (2D) layer structures with considerable stability in aqueous media within a wide pH range (pH = 2-12).
Abstract: Two luminescent coordination polymers (CPs), {[Cd2L2(H2O)4]·H2O}n (1) and {[Zn2L2(H2O)4]·H2O}n (2) (H2L = 5-(1H-1,2,4-triazol-1-yl)isophthalic acid) are reported herein. The CPs reveal readily dispersible two-dimensional (2D) layer structures with considerable stability in aqueous media within a wide pH range (pH = 2–12). Sensing experiments indicate that they can serve as highly selective and sensitive fluorescent probes toward CrVI-anions (CrO42− and Cr2O72−).
TL;DR: Solvent luminescence studies, pH stability and PXRD data indicate that complexes 1 and 2 can be used as excellent water-stable multi-response luminescent sensors for detecting a wide variety of toxic substances.
Abstract: Lanthanide MOFs (Ln-MOFs), {[Ln2(L)2(H2O)2]·5H2O·6DMAC}n, [Ln||| = Eu(1) and Tb(2); H3L = 4,4'-(((5-carboxy-1,3-phenylene)bis(azanediyl))bis(carbonyl)) dibenzoic acid, DMAC = N,N'-dimethylacetamide], with a new topology type have been isolated. Single crystal X-ray diffraction indicates that complexes 1 and 2 are isostructural with binuclear [Eu2(COO)7]n secondary building units as 7-connected nodes and H3L ligands as 3-connected nodes and can be viewed as a (5,7)-connected 3D framework with a new topological point symbol of {32·44·54} {34·46·56·65}. Complexes 1 and 2 exhibit an excellent luminescence sensing response to inorganic ions Fe3+, Cr2O72-, MnO4- and 4-nitrophenol, with a low detection limit and high Ksv value. Interestingly, when the MnO4- ions are detected, the color of the solid sample is observed to change from yellow to brown, visually indicating luminescence induction, which makes the process of detecting MnO4- ions simpler and more practical. Moreover, by using time-resolved photoluminescence techniques, complex 1 can effectively eliminate background fluorescence interference during detection and improve detection accuracy. Solvent luminescence studies, pH stability and PXRD data indicate that complexes 1 and 2 can be used as excellent water-stable multi-response luminescent sensors for detecting a wide variety of toxic substances. In addition, the mechanism of selective detection is explained by the energy competition between the excitation of complexes 1 and 2 and the ultraviolet absorption of the responsive substance.
TL;DR: Although these Cu-MOFs were found to be structurally very stable in aqueous medium during antibacterial activity tests, they exhibited excellent antibacterial activities against all five kinds of bacteria, including Gram-positive bacteria and Gram-negative bacteria, with very low MBCs.
Abstract: Metal-organic frameworks (MOFs) can be utilized as antibacterial agents due to their effective antibacterial activities. Four three-dimensional (3D) Cu-MOFs formulated as [Cu2(Glu)2(μ-L)]·x(H2O) (Glu is glutarate, and L is bpy = 4,4'-bipyridine (1), bpa = 1,2-bis(4-pyridyl)ethane (2), bpe = 1,2-bis(4-pyridyl)ethylene (3), and bpp = 1,2-bis(4-pyridyl)propane (4)) were synthesized by hydrothermal reactions or modified literature methods. Their solid-state structures were slightly modified to increase their hydrolytic stabilities in aqueous solution. Despite the seemingly sufficient void spaces in all the solvent-free MOFs, only the thermally activated form of MOF 2 displayed selective gas uptake ability for CO2 over N2 and H2. The antibacterial activities of the four Cu-MOFs, 1, 2, 3, and 4, were investigated by determining their minimal bactericidal concentration (MBC) values against five strains of bacteria, including E. coli, S. aureus, K. pneumonia, P. aeruginosa, and MRSA, which can be easily met in our daily surrounding environments. Although these Cu-MOFs were found to be structurally very stable in aqueous medium during antibacterial activity tests, they exhibited excellent antibacterial activities against all five kinds of bacteria, including Gram-positive bacteria (S. aureus and MRSA) and Gram-negative bacteria (E. coli, K. pneumonia, and P. aeruginosa), with very low MBCs. The robust 3D frameworks with surface active metal sites rather than the small amount of leached CuII ions may participate more strongly in inactivating various kinds of bacteria and reduce potential cytotoxicity mainly caused by leached metal ions.
TL;DR: This work design, synthesize, and characterize mono-disperse, dumbbell-shaped lanthanide-doped NaYF4@NaGdF4 core-shell nanoparticles (CSNPs) with dual-mode fluorescence, which provide a simple and promising material and technique for anti-counterfeiting applications.
Abstract: Development of advanced luminescent nanomaterials and technologies is of great significance for anti-counterfeiting applications in global economy, security, and human health, but has proved to be a great challenge. In this work, we design, synthesize, and characterize mono-disperse, dumbbell-shaped lanthanide-doped NaYF4@NaGdF4 core-shell nanoparticles (CSNPs) with dual-mode fluorescence by coating the NaGdF4:Ln'3+ shell onto NaYF4:Ln3+ core nanospheres via a two-step oleic acid mediated thermal decomposition process. Different from the conventional synthesis method to produce spherical nanoparticles, the epitaxial growth of the NaGdF4:Ln'3+ shell onto the nanosphere cores and the lattice mismatch between β-NaGdF4 and β-NaYF4 nanocrystals enable the formation of dumbbell-shaped CSNPs, as evidenced by the morphological evolution of CSNPs and as explained by the Ostwald ripening growth mechanism. By tailoring different doped lanthanide ions in the core and the shell, the resultant CSNPs exhibit tunable but different up-/down-conversion luminescence under the irradiation of a 980 nm laser and 254 nm UV light, respectively. Finally, these hydrophilic CSNPs are further fabricated into environmentally benign luminescent inks for inkjet printing to create a variety of dual-mode fluorescent patterns (peacock, temple, and a logo of "Hunan University of Technology") on different paper-based substrates (A4 paper, envelope, and postcard). Our dual-mode light-responsive CSNPs, along with an easy fabrication method, provide a simple and promising material and technique for anti-counterfeiting applications.
TL;DR: 1 shows stable catalytic efficiency after five reaction cycles, which indicates that 1 exhibits efficient catalytic activity and good reusability toward the degradation of organic dyes, enabling it to be a potential candidate for environmental governance.
Abstract: A novel 2D zinc(ii) metal-organic framework, formulated as [Zn(L)(H2O)]·H2O (1) (H2L = 4-(pyridine-4-yl) phthalic acid), has been successfully obtained under solvothermal conditions. This metal-organic framework (MOF) material exhibits efficient photocatalytic activity towards the degradation of organic dyes in the absence of any photosensitizer or cocatalyst. Its catalytic performance for rhodamine B (RhB) and methyl orange (MO) degradation was superior to most reported MOFs with a degradation efficiency of 98.5% for RhB and 83.8% for MO within 120 min in the absence of H2O2, which could be attributed to its high efficiency in generating ·O2- (an effective oxidant for the degradation of dyes). The possible mechanism of the reaction was discussed in detail. In addition, 1 shows stable catalytic efficiency after five reaction cycles, which indicates that 1 exhibits efficient catalytic activity and good reusability toward the degradation of organic dyes, enabling it to be a potential candidate for environmental governance.
TL;DR: Catalytic studies showed that Ag@TPHH-COF could catalyze the reduction of the various nitroaromatic compounds (NACs) with high efficiency, such as 4-nitrophenol, 2-nitroaniline, nitrobenzene, 4-Nitrotoluene and 1-butyl-4-nitrifying compounds, and has good reusability and high recovery.
Abstract: A covalent organic framework (COF) featuring a unique light porous structure and silver nanoparticles shows high efficiency in the degradation of environmental pollutants. However, the combination of a COF with silver nanoparticles has never been reported until now. Toward this end, 2,4,6-tris-(4-formylphenoxy)-1,3,5-triazine (TPT-CHO) and hydrazine hydrate were selected as the construction units of the COF material (TPHH-COF), which possesses rich nitrogen and oxygen sites. Then a new type of composite catalyst (Ag@TPHH-COF) was successfully obtained by solution infiltration. The obtained materials were also fully characterized by standard methods. The results showed that the silver nanoparticles (with diameters of 5 ± 3 nm) were uniformly dispersed on the surface and in the interlayer gaps of the TPHH-COF substrate. Catalytic studies showed that Ag@TPHH-COF could catalyze the reduction of the various nitroaromatic compounds (NACs) with high efficiency, such as 4-nitrophenol, 2-nitrophenol, 4-nitroaniline, nitrobenzene, 4-nitrotoluene and 1-butyl-4-nitrobenzene. Ag@TPHH-COF could also catalyze the reduction of organic dyes such as Rhodamine B (RhB), Methylene Blue (MB), Methyl Orange (MO) and Congo Red (CR). Moreover, Ag@TPHH-COF has good reusability and high recovery.
TL;DR: Two-dimensional transition metal carbides (MXenes) are investigated as scavengers of cesium (Cs+) from contaminated water and showed an excellent Cs+ removal efficiency in neutral to slightly alkaline solutions.
Abstract: Industrial utilization of nuclear resources greatly depends on the effective treatment of nuclear waste. The efficient removal of radioactive nuclides from liquid effluents by using different adsorbents has thus become crucial. Herein, for the first time, two-dimensional transition metal carbides (MXenes) are investigated as scavengers of cesium (Cs+) from contaminated water. Due to the combined advantages of the layered structure and the presence of heterogeneous sites (hydroxyl, oxygen and fluorine groups), the adsorbent reached the steady state within 1 min with the maximum Cs+ adsorption capacity of 25.4 mg g−1 at room temperature. The kinetics studies of the Cs+ scavenging process demonstrated that the adsorption of Cs+ followed the pseudo-second-order model whereas the adsorption equilibrium data obeyed the Freundlich model. Thermodynamic studies revealed that the adsorption process was endothermic. The adsorbent showed an excellent Cs+ removal efficiency in neutral to slightly alkaline solutions. Moreover, it can retain Cs+ even in the presence of a high concentration of competing cations (Li+, Na+, K+, Mg2+ and Sr2+). The Cs+ loaded adsorbent was regenerated with a 0.2 M HCl solution and reused at least five times for over 91% removal of contaminants.
TL;DR: This is the first example of a MOF-based multiresponsive fluorescent probe for the simultaneous detection of Fe(iii), Cr(iii/vi), Mn(vii) and the pesticide 2,6-Dich-4-NA in aqueous solution.
Abstract: A novel metal–organic framework with the formula [Zn3(DDB)(DPE)]·H2O (1) (H5DDB = 3,5-di(2′,4′-dicarboxylphenyl)benzoic acid and DPE = 1,2-di(4-pyridyl)ethylene) has been solvothermally synthesized by employing a rigid carboxylate ligand H5DDB to assemble with Zn(II) ions in the presence of a flexible bis(pyridyl) linker DPE. The Zn-MOF is a 3D framework with six-nuclear clusters and possesses remarkable water stability and pH stability. Interestingly, complex 1 can sensitively and selectively sense Fe(III), Cr(III), Cr(VI), Mn(VII) and the pesticide 2,6-Dich-4-NA with low detection limits in aqueous solution. Moreover, complex 1 also exhibits selectivity for 2,6-Dich-4-NA detection in real samples including carrot, grape and nectarine extracts, and its detection ability is almost unchanged in the presence of the surfactant sodium dodecyl sulfate (SDS). The possible mechanisms of luminescence quenching have been explained by the weak affinity of nitrogen atoms, resonance energy transfer, and photoinduced electron transfer. To our knowledge, this is the first example of a MOF-based multiresponsive fluorescent probe for the simultaneous detection of Fe(III), Cr(III/VI), Mn(VII) and the pesticide 2,6-Dich-4-NA in aqueous solution.
TL;DR: Three zinc-viologen compounds, constructed from aromatic carboxylic acid and viologen-derived ligands, display photochromic properties from pale yellow to dark blue after being irradiated by a xenon lamp with different photoresponsive rates.
Abstract: Three zinc-viologen compounds, namely, {[Zn(Mebpy)(Hbtc)Cl]·2H2O}n (1), {[Zn3(Cebpy)2(Hbtc) (H2btc)2 (OH)2]·4H2O}n (2), and {[Zn4(Cebpy)2(IPA)3(OH)2]·2H2O}n (3) (Mebpy = N-methyl-4,4'-bipyridinium, Cebpy = N-carboxyethyl-4,4'-bipyridinium, H3btc = 1,3,5-benzenetricarboxylic acid, and H2IPA = isophthalic acid) have been constructed from aromatic carboxylic acid and viologen-derived ligands. In compound 1, the Hbtc2- ligands bridge Zn2+ cations to form a 1D fence-like chain with the Mebpy+ ligand suspended on the chains. Compound 2 possesses a 2D (4, 4) double-layered grid structure based on linear trinuclear Zn3O2 cluster units. The structure of compound 3 can be described as a 3D open-framework based on tetranuclear Zn4O2 cluster units and helical chains with helical channels. All three compounds display photochromic properties from pale yellow to dark blue after being irradiated by a xenon lamp with different photoresponsive rates. Compounds 2 and 3 can be deposited in paper simply by coating them with a solution of ethanol. The papers can be used as inkless and erasable print media. In addition, the photo-modulated luminescence of these compounds was also investigated.
TL;DR: Considering the notable properties of the electrodes, a flexible asymmetric all-solid-state device based on graphene-wrapped NiCo2Se4 microspheres and petal-like iron disulfide (negative electrode) was assembled and exhibits the high specific capacitance, the significant energy density, and excellent flexibility.
Abstract: Herein, we proposed a desirable strategy for the synthesis of graphene-wrapped NiCo2Se4 microspheres (positive electrode) and petal-like iron disulfide (FeS2) (negative electrode) on nickel foam substrates. The positive electrode represents a substantial specific capacitance of 2112.30 F g-1 and excellent durability (6.8% loss after 5000 cycles). Furthermore, the negative electrode reflects good electrochemical performance with a specific capacitance of 321.30 F g-1 and a satisfactory rate capability of 47% capacitance retention. Considering the notable properties of the electrodes, a flexible asymmetric all-solid-state device based on graphene-wrapped NiCo2Se4 microspheres (positive electrode) and petal-like iron disulfide (negative electrode) was assembled. Our flexible device exhibits the high specific capacitance of 221.30 F g-1, the significant energy density of 78.68 W h kg-1 and excellent flexibility.
TL;DR: The luminescence performance revealed that Ca18Li3Bi1-xEux(PO4)14 phosphors could emit intense red emission under 394 nm excitation with excellent CIE chromaticity coordinates and high color purity.
Abstract: To research and develop potential phosphors for ultraviolet-based white light emitting diodes, a novel red emission phosphate phosphor Ca18Li3Bi1-xEux(PO4)14 was synthesized and investigated in the full range of 0 ≤x≤ 1. The phase purity and crystal structure of the solid solution phosphors were investigated in detail by employing X-ray diffractometer structure refinement, scanning electron microscopy and energy dispersive spectrometry. The crystal structure information was confirmed and the structure as well as the doping concentration dependent characteristic photoluminescence properties were discussed in detail. The results indicated that high Eu3+ doping content x could be realized in Ca18Li3Bi1-xEux(PO4)14 solid solutions even when x = 1. The luminescence performance revealed that Ca18Li3Bi1-xEux(PO4)14 phosphors could emit intense red emission under 394 nm excitation with excellent CIE chromaticity coordinates and high color purity. The concentration dependent emission decay behavior at room temperature and the temperature dependent decay behavior were studied to investigate the luminescent dynamics. The abnormal thermal quenching behavior was investigated via the temperature dependent emission. The related mechanism was discussed through thermoluminescence analysis, charge compensation contrast test and the cooling emission curve measurement, and the thermal activation energy was studied. The above results indicated that the Ca18Li3Bi1-xEux(PO4)14 could be a promising red-emitting phosphor for white light emitting diodes.
TL;DR: A simple assay based on aggregation-caused quenching of sulfur quantum dots (SQDs) to detect cobalt ions (Co2+) and a new determination strategy of norfloxacin was built using the S QDs as a "switch".
Abstract: Sulfur nanomaterials exceed carbon nanomaterials in terms of the antimicrobial or antifungal properties. To date, there have been no reports on sulfur dots being used as fluorescence sensors. Herein, we report a simple assay based on aggregation-caused quenching (ACQ) of sulfur quantum dots (SQDs) to detect cobalt ions (Co2+). The S QDs allows the detection of Co2+ ions in the range of 0–9 × 10−5 mol L−1. This reliable, rapid, sensitive, and selective S QD probe has been utilized for the determination of the concentrations of Co2+ ions in water samples (I = 61.89C + 1.72, R2 = 0.9485). After adding norfloxacin, the fluorescence intensity recovered. There were good linear correlations between the concentrations of norfloxacin and the fluorescence-recovered intensities. A new determination strategy of norfloxacin was built using the S QDs as a “switch”. The recovered photoluminescence intensity of S QDs-Co2+ was proportional to the concentration of norfloxacin in the range of 0–2 × 10−4 mol L−1 (I = −44.18C + 138.45, R2 = 0.9943). Co2+ coordinated with the carbonyl oxygen and the hydroxyl oxygen on the side chain of the norfloxacin molecule. This is the first time S QDs were used as a sensing platform.
TL;DR: The as-fabricated leaf-like Co3O4@NiCo2O4 nanoarrays hold great promise as binder-free electrodes in electrochemical energy storage devices.
Abstract: A rational design of heterostructures for electrode materials is highly desired for boosting the electrochemical performance, but it is still challenging, especially through a cost-effective method. Herein, novel NiCo2O4 nanosheet-decorated leaf-like Co3O4 nanoarrays have been constructed on a Ni foam using a leaf-like Co-based metal–organic framework (Co-MOF-L) template, which can be simply prepared in an aqueous solution at room temperature. Combining the merits of MOF derivatives and the free-standing core–shell heterostructure, the leaf-like Co3O4@NiCo2O4 nanoarray electrode displayed a high specific capacity of 544.2 C g−1 at 1 A g−1, which is almost 9.3 times that of Co3O4 (58.3 C g−1) and 6 times that of NiCo2O4 (92.1 C g−1). It also displayed a good rate capacity (65.5% at 10 A g−1) and superior long-term stability (93.0% capacity retention over 5000 cycles at 10 A g−1). Moreover, a hybrid supercapacitor (HSC) assembled from the battery-type Co3O4@NiCo2O4 electrode and a capacitive activated carbon (AC) electrode delivered a high energy density of 36 W h kg−1 at a high power density of 852 W kg−1 with good cycling stability, demonstrating a capacity retention of 89.5% after 10 000 cycles at 10 A g−1. Furthermore, two connected HSCs could light up a red light-emitting diode (LED). Therefore, the as-fabricated leaf-like Co3O4@NiCo2O4 nanoarrays hold great promise as binder-free electrodes in electrochemical energy storage devices.