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Theoretical calculation results unveil that the reconstructed Co(Ni)OOH on FeNiCo-MOF during OER processes is beneficial to improve the OER activity. Experimentally, to achieve 2D trimetallic FeNiCo-MOF nanosheets, a facile room-temperature dispersion approach is employed. Such 2D nanosheets reveal an OER overpotential as low as 239 mV at 10 mA cm−2 and excellent long-term stability in 1M KOH. Undoubtedly, this work highlights the great potential of directly utilizing MOF nanosheets as OER electrocatalysts. [ABSTRACT FROM AUTHOR]

A zinc-based metal–organic framework was constructed by a solvothermal synthesis approach with the formula {[Zn3(ttta)2(H2O)4]}n (1–Zn) (where H3ttta = 4,4′,4′′-(1,3,5-triazine-2,4,6-triazinediyl) triazinic acid) and was successfully characterized. In terms of photocatalytic degradation, complex 1–Zn has a smaller energy band gap and higher degradation efficiency compared to many other Zn-MOFs, and it has good stability and recyclability. Fluorescence detection experiments showed that complex 1–Zn showed significant specificity in recognition of quinolone antibiotics compared to other antibiotics and showed a better fluorescence quenching rate of metronidazole (MDZ) and tetracycline hydrochloride (TCH). The photodegradation mechanism was investigated by ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) and valence band X-ray photoelectron spectroscopy (VB-XPS). A reasonable mechanism of the fluorescent probe and photodegradation of 1–Zn was determined by density functional theory calculations. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) are highly promising as a novel class of drug delivery carriers; however, there are few reports about their application in nanoparticle-based formulations for dermal administration. In this work, we developed a novel kind of nanoparticular system based on zeolitic imidazolate framework-8 (ZIF-8) and polydopamine (PDA) modification for improving the dermal delivery of 5-fluorouracil (5-FU). The structures and properties of the prepared nanoparticles were characterized using a variety of analytical methods. Their ex vivo delivery performance in the skin was investigated using Franz cells, and the underlying mechanisms were studied via confocal laser scanning microscopy (CLSM) and hematoxylin-eosin (HE) experiments which were employed to probe the penetration pathway and the interaction between nanoparticles and the skin. The results revealed that both 5-FU@ZIF-8 and ZIF-8@5-FU@PDA had an enhancement effect on the deposition of 5-FU in the skin, and the surface coating of PDA could further reduce drug permeation across the skin, especially in the case of impaired skin, in comparison with the drug solution. The CLSM study using rhodamine 6G as the fluorescent probe to mimic 5-FU indicated that ZIF-8 and ZIF-8@PDA could deliver their payloads into the skin via two pathways, i.e., intercellular and follicular ones, and the follicular route was shown to be particularly important for ZIF-8@PDA, in which the drug and carrier were co-delivered into the skin as an intact particle. This study provides evidence for using ZIF-8 and PDA modification for skin-specific drug delivery and offers an effective avenue to develop novel nanoplatforms for dermal application to treat skin diseases. [ABSTRACT FROM AUTHOR]

A novel 3D open-framework copper borovanadate with a unique crown-shaped anion [(VIVO)8(VVO)4B32O64(OH)8]12− and the largest ratio of Cu2+/borovanadate anions (6/1) has been successfully synthesized and systematically studied. The compound not only possesses high stability in a wide pH range of 3.2–10.8 (DMF solution), but also exhibits excellent catalytic activities for selective oxidation of sulfides. [ABSTRACT FROM AUTHOR]

A series of four novel 3-D Ln-MOFs containing both carboxyphenyl and pyridinyl moieties, with the general formula [Ln2(tcptp)(btca)(H2O)m]n {Ln = Sm3+(1), m = 13; Eu3+(2), m = 12; Gd3+(3) m = 13 and Tb3+(4), m = 14; H3tcptp = 4-(2,4,6-tricarboxyl phenyl)-4,2′:6′,4′′-terpyridine}, have been constructed. During reaction, benzene-1,2,3,5-tetracarboxylic acid (H4btca) was generated in situ as a second linker, resulting in the formation of a 3D framework, bearing 1D elliptical channels. MOF-1 exhibits dual emissions based on the ligand and Sm3+, through which single-component complementary near-white-light emission was realized. Both MOF-2 and MOF-4 display strong ligand–metal charge transfer (LMCT) emissions due to an antenna effect. Remarkably, for MOF-4, Tb3+-based fluorescence turn-on sensing of levofloxacin in solution with high sensitivity and excellent selectivity was achieved through a donor photoinduced electron transfer (d-PET) approach, which distinguishes it from other antibiotics, meaning that MOF-4 can be employed as a promising specific fluorescence sensor. [ABSTRACT FROM AUTHOR]

Two transition metal complexes {[Co2(bpda)4(H2O)2]·4H2O}n(Co-1) and {[Ni(bpda)2(H2O)2]·2H2O}(Ni-2) (H2bpda = 2,2′-bipyridine-4,4′-dicarboxylic acid) have been synthesized by a hydrothermal method and characterized. These two compounds can be explored as stable electrocatalysts in the hydrogen evolution reaction (HER) using two important parameters: the overpotential and Tafel slope (TS). Electrochemical studies suggest that the reaction kinetics of a Co-1 catalyst is more favorable than that of a Ni-2 catalyst. Co-1 exhibits better HER performance with an overpotential of 182 mV at a current density of 10 mA cm−2, a small TS of 87.21 mV dec−1 and superior long-term durability (of up to 3000 cycles). Structural analysis shows that its catalytic activity is improved due to the two mixed valence cobalt ions and the pore structure formed by hydrogen bonds in Co-1, which is different from that of Ni-2. In addition, the mechanism of the HER is also explained theoretically by DFT molecular orbital and free energy calculations in this article. [ABSTRACT FROM AUTHOR]

Herein, unique N,O-codoped porous biocarbon (PB) was prepared using Ephedra Herb (EH) as a precursor via a green and sustainable NaCl-sealing strategy and subsequent pyrolysis method. PB possesses vast microstructure, interlinked pores, and high specific surface area, which can facilitate ion adsorption and buffering to improve its properties as an electrode material. In addition, the high specific surface area, well-developed porosity, and abundant heteroatoms in EH are retained well owing to the salt-sealing approach, contributing to additional pseudocapacitance. Therefore, a typical PB sample (S12), obtained from the NaCl-sealing and pyrolysis of the mixture of EH and NaCl at a mass ratio of 1 : 2, is endowed with high specific capacitance, excellent rate performance, and performance retention over long-term cycling. Most importantly, an aqueous symmetrical supercapacitor (S12//S12) assembled with S12 electrodes has a superior specific energy density of 11.6 W h kg−1 at a specific power density of 450.1 W kg−1 in Li2SO4 electrolyte. This work confirms the utility of a NaCl-sealing strategy for designing high specific surface area biocarbon materials that are ultra-rich in micropores, and it sheds some light on the use of sustainable and low-cost synthetic carbon that is ultra-rich in micropores to meet energy-storage device requirements. [ABSTRACT FROM AUTHOR]

In this paper, three isostructural 1D lanthanide complexes, [Ln(dppc)(H2O)4]n·2nH2O (Ln = Eu, Tb and Eu0.501Tb0.499, named 1-Eu, 2-Tb and Eu0.501Tb0.499), based on 3-(2,4-dicarboxylate phenyl)-2-pyridinecarboxylic acid (H3dppc) have been synthesized and characterized by elemental analysis, IR, PXRD, TG and X-ray crystallography. The complexes exhibit a 1D chain structure, which is further linked into a 3D supramolecular framework by hydrogen bonds. Tuneable emission colour of Eu0.501Tb0.499 is realized by adjusting the excitation wavelength. The sensing properties of 1-Eu and 2-Tb towards Fe3+ and aniline indicate that the two complexes have almost the same superior sensitivity and low detection limit for Fe3+ in aqueous solution, while they have different detection abilities for aniline in DMF solvent. The different detection abilities were discussed by means of PXRD, UV-vis, luminescence lifetimes and molecular surface calculations (Hirshfeld surface analysis and 2D fingerprint plots). [ABSTRACT FROM AUTHOR]

A series of isostructural lanthanide coordination polymers (Ln-CPs) formulated as [Ln(tcptpy)(H2O)2·2H2O]n {Ln3+ = Sm3+ (1), Eu3+ (2), Gd3+ (3), Tb3+ (4), Dy3+ (5); H3tcptpy = 4-(2,4,6-tricarboxylphenyl)-4,2′:6′,4′′-terpyridine} has been afforded and characterized systematically. Their structures were established by single-crystal X-ray diffraction. All the complexes feature two dimensional (2D) layers with (4,4)-connected topology. By virtue of the isostructural frameworks, a family of binary co-doped Ln-CPs [Tb1−xEuxtcptpy]n was achieved for ratiometric temperature sensors, among which Tb0.897Eu0.103tcptpy exhibits a good linear response to the temperature range from 305–340 K, with a maximum relative sensitivity (Sm) of 8.41% K−1 at 340 K. Moreover, Tb-CPs exhibit excellent applications as luminescent sensors for the detection of nitrobenzene and Fe3+ cations with high selectivity and sensitivity based on a luminescence quenching approach. The possible mechanisms of the fluorescence quenching effect were also investigated. [ABSTRACT FROM AUTHOR]

Desulfurization of syngas from coal gasification is an essential process in chemical synthesis to achieve high value-added utilization of coal. The hydrogenation conversion method is known for its high desulfurization degree in organic sulfur removal, but it is hindered by severe operating conditions, which leads to low safety and low efficiency. A Mg–carbon composite is synthesized by a reactive ball-milling method to store solid-phase hydrogen with high activity for CS2 hydrogenation. Without the presence of high-pressure gaseous hydrogen, CS2 in the stream is hydrogenated by the composite at 250 °C to yield CH4 and H2S, and the conversion achieved is over 91.8% in 300 min. First-principles calculations reveal that chemisorption structures can influence the reaction of CS2 with MgH2, in which horizontal chemisorption is in favor of the generation of gaseous H2S while vertical chemisorption can result in solid MgS. This new method of hydrogenation paves the way for organic sulfur compound removal at moderate temperatures without using a high-pressure hydrogen atmosphere. [ABSTRACT FROM AUTHOR]

A series of coordination polymers {[Ln(aobtc)(H2O)4]·Hbipy·H2O}n (H4aobtc = azoxybenzene-2,2′,3,3′-tetracarboxylic acid, bipy = 4,4′-bipyridine, and Ln = Sm(1), Eu(2), Gd(3), Tb(4), Dy(5), Er(6)) have been synthesized and characterized systematically. The cationic Hbipy+ guest incorporated polymers are isostructural sets, featuring a one-dimensional (1D) zigzag double chain edifice composed of binuclear clusters [Ln2(H4aobtc)2], with the Hbipy+ guest being located on two sides. These 1D chains are further interlinked into a 2D layer structure, and further extended into a 3D framework through hydrogen bonding interactions. The luminescence emission spectra of polymers 2 and 3 are based on the H4aobtc acid ligands, while 1 and 4 display the characteristic f–f transitions of Ln(iii) ions. Magnetic measurements revealed the presence of ferromagnetic behavior in polymer 3. The magnetic behaviors of 4 and 6 are ascribed to the depopulation of the Stark levels and/or weak antiferromagnetic interactions within MOFs at lower temperature. Slow relaxation is observed through the alternating-current susceptibility measurements for 5 at lower temperature, and the coexistence of weak ferromagnetism corresponding to the spin-canting-like behavior. [ABSTRACT FROM AUTHOR]

A family of six new homo-lanthanide coordination polymers incorporating a conjugated ligand of 2,5-di(2′,4′-dicarboxylpheny)pyridine, namely, {[Ce(μ3−ddpp)]·4H2O}n (1), {[Nd(μ3−ddpp)]·2H2O}n (2), {[Sm(μ6−ddpp)]·H2O}·H2O}n (3), {[Eu(μ6−ddpp)]·H2O}n (4), {[Tb(μ6−ddpp)]·H2O}n (5), and {[Er(μ6−ddpp)]·H2O}n (6) (H3ddpp = 2,5-di(2′,4′-dicarboxylpheny)pyridine acid), has been prepared successfully through solvothermal reactions. Polymers 1–6 exhibit various coordination environments and different multi-dimensions, but they are all assembled in a one dimensional (1-D) Ln–carboxylate chain. Polymer 1 only shows a 1-D ribbon chain, while polymer 2 exhibits a binodal (3, 8)-connected topology net. Heavy lanthanide polymers 4–6 possess 3D frameworks based on a rare (4, 8)-connected msw framework. Thermogravimetric and different thermal analysis measurements indicate that they all display high thermal stability. The luminescence emission spectra display characteristic f–f transition emissions of Ln(iii) polymers in visible or near infrared (NIR) regions. The fluorescent ligand H2ddpp provides efficient energy transfer for the sensitization of Eu(iii) and Tb(iii) ions in the visible region, among which a Tb(iii) polymer may be employed as a fluorescence ratiometric probe for the pollutant CrO42− anion. [ABSTRACT FROM AUTHOR]

Controllable engineering of high-electronegativity oxygen (O)-heteroatoms into MoS2 ultrathin nanosheets is realized via a facile post-modification process. The incorporated oxygen atoms impart a dramatically enhanced ORR activity to the pristine nanosheets, with a 7.8-fold current increase as well as 180 mV and 160 mV positive shifts in both onset and half-wave potentials that are almost comparable with the commercial Pt/C catalyst. Furthermore, oxygen incorporation also triggers a transformation of the process from two-electron to a four-electron process. The improved topical conductivity, as well as the preferential adsorption of oxygen molecules originating from the heteroatoms engineering is supposed to be responsible for the efficient ORR. The prospect of controllably engineering heteroatoms into MoS2 ultrathin nanosheets with versatile applications is also highlighted in this work. [ABSTRACT FROM AUTHOR]

Engineering phosphorus heteroatoms into the plane of ultrathin MoS2 nanosheets is realized via a facile thermolytical process. The doping of low-electronegative P atoms generates an extra ORR activity with four-electron selectivity, manifesting seven-fold current increase as well as 160 mV positive shift in both onset and half-wave potentials. [ABSTRACT FROM AUTHOR]

MoS2 nanodots (NDs) were successfully embedded in the three-dimensional (3D) porous frameworks of N-doped graphene (NGr) via in situ pyrolysis of glucose, a layered C3N4 sacrificial template and monolayered MoS2 NDs. The monolayered MoS2 NDs were hydrothermally pre-synthesized and acted as size-controlled precursors. By varying the content of the MoS2 NDs, a series of MoS2 NDs/NGr was obtained, which displayed amendable activity towards oxygen reduction reaction (ORR) in basic solution, due to the balance between the exposed edge sites of the MoS2 NDs and the internal conductive channels of the 3D porous NGr. The optimal composition generated an efficient Pt-free ORR catalyst with good four-electron selectivity, and was shown to have a more positive shift in both the onset and peak potentials than its counterparts. The novel catalyst also demonstrated superior tolerance against methanol and better durability than commercial Pt/C. [ABSTRACT FROM AUTHOR]

Uniform iron carbide nanoparticles (Fe3C, ∼10 nm), size evolved from nano-scaled Fe-MIL-88b, were one-pot pyrolytically embedded in 3D porous N-rich graphene. Extra ORR catalytic activity with four-electron selectivity was achieved in an alkaline electrolyte. The onset and peak potential were 10 mV and 40 mV more positive, respectively, than commercial Pt/C. [ABSTRACT FROM AUTHOR]

Reactions of lanthanide(iii) nitrates with multi-donor carboxylate ligand in the presence of oxalate anion afforded four new lanthanide coordination polymers with three dimensional (3D) frameworks, namely, {[Ln2(DPPA)2(μ2-C2O4)(H2O)2]·2H2O}n (Ln = Nd (1), Sm (2)) and [Ln2(HDPPA)2(DPPA)2]n (Ln = Tb (3), Yb (4)), (H3DPPA = 3-(4-hydroxyl pyridinium-1-yl) phthalic acid and H2C2O4 = oxalic acid). Compounds 1 and 2 are isostructural and isomorphous, featuring oxalate pillared binodal (4,5)-connected porous 3D framework with intersected 1D channels, in which the coordinated and lattice waters are accommodated. The complexes 3 and 4 are also isostructural, but featuring a (4,6)-connected 3D network based on a rectangular window composed of {Ln(HDPPA)}+ extended anion chains, further interlinked by DPPA. The Tb(iii) analogue exhibits intense characteristic green photoluminescence employing DPPA as an antenna. While Sm(iii) compound 2 mainly involves ligand-to-ligand charge transfer. Variable-temperature susceptibility analyses of complexes 1 (Nd), 2 (Sm) and 3 (Tb) revealed that depopulation of the Stark levels together with weak antiferromagnetic interactions between the lanthanide ions lead to a continuous decrease in χMT when the samples are cooled from 300 to 2 K. [ABSTRACT FROM AUTHOR]

A novel three-dimensional non-interpenetrated nanoporous polymeric complex {[Dy(ABTA)]·2H2O}n, (H3ABTA = azobenzene-3,5,4′-tricarboxylic acid) with centro-symmetric six connected binuclear dysprosium as the building block has been designed from the rational synthetic approach and has been characterized and evaluated systematically. [ABSTRACT FROM AUTHOR]

Seven new lanthanide–organic coordination polymers incorporating both nitrogen heterocyclic dicarboxylate and various auxiliary ligands, {[Ln3(Hpimda)4(μ2-HCOO)·5H2O]·H2O}n} Ln = Sm (1), Ln = Eu (2), Ln = Gd (3), Ln = Dy (4), Ln = Ho (5), {[Ce2(Hpimda)2(μ4-C2O4)·8H2O]·2H2O}n(6), {[Yb2(pyda)(μ4-C2O4)2·4H2O]·3H2O}n(7) (H3pimda = 1H-2-propyl-4,5-imidazoledicarboxylic acid, H2pyda = 2,6-pyridinedicarboxylic acid) have been fabricated successfully and characterized systematically. Complexes 1–5are isomorphous and isostructural, and are built from two-dimensional (2-D) double-decker networks based on the tetranuclear basic carboxylate as a secondary building unit (SBU). Both polymers 6and 7feature a (3,4)-connected 3-D framework consisting of 2-D lanthanide–organic hexagonal grids, which are further interlinked viathe μ4-oxalate ligand. The results of magnetic determination show the same end-to-end bridging fashion of formate group results in different magnetic properties occurring between lanthanide centers. The luminescence emission spectra of the complexes vary depending on the lanthanide ion present. [ABSTRACT FROM AUTHOR]

A novel 3D open-framework copper borovanadate with a unique crown-shaped anion [(V IV O) 8 (V V O) 4 B 32 O 64 (OH) 8 ] 12- and the largest ratio of Cu 2+ /borovanadate anions (6/1) has been successfully synthesized and systematically studied. The compound not only possesses high stability in a wide pH range of 3.2-10.8 (DMF solution), but also exhibits excellent catalytic activities for selective oxidation of sulfides.

Two transition metal complexes {[Co 2 (bpda) 4 (H 2 O) 2 ]·4H 2 O} n (Co-1) and {[Ni(bpda) 2 (H 2 O) 2 ]·2H 2 O}(Ni-2) (H 2 bpda = 2,2'-bipyridine-4,4'-dicarboxylic acid) have been synthesized by a hydrothermal method and characterized. These two compounds can be explored as stable electrocatalysts in the hydrogen evolution reaction (HER) using two important parameters: the overpotential and Tafel slope (TS). Electrochemical studies suggest that the reaction kinetics of a Co-1 catalyst is more favorable than that of a Ni-2 catalyst. Co-1 exhibits better HER performance with an overpotential of 182 mV at a current density of 10 mA cm -2 , a small TS of 87.21 mV dec -1 and superior long-term durability (of up to 3000 cycles). Structural analysis shows that its catalytic activity is improved due to the two mixed valence cobalt ions and the pore structure formed by hydrogen bonds in Co-1, which is different from that of Ni-2. In addition, the mechanism of the HER is also explained theoretically by DFT molecular orbital and free energy calculations in this article.

Sodium iron fluoride (Na 3 FeF 6 ) is a colorless ferromagnetic fluoride with a monoclinic crystal structure (space group P 21/ c ), and it is expected to be an ideal platform for exploring magneto-optical interactions. In the present work, Eu 3+ doped Na 3 FeF 6 micro-powders were synthesized by a hydrothermal method, and the structures were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The optical properties were examined using UV-Vis spectra and fluorescence spectra, and the results show that the emission spectra can be finely tuned by the hydrothermal reaction temperature and doping concentration of Eu ions. We found that Na 3 FeF 6 doped with 5% Eu 3+ synthesized at 196 °C exhibited the optimal red emission under excitation at 395 nm. The magnetization of Na 3 FeF 6 :5% Eu 3+ decreased rapidly from about 7.85 emu g -1 at 5 K to 0.4 emu g -1 at 60 K, then slowly decreased with temperature increase from 60 K to 300 K. This Eu 3+ doped Na 3 FeF 6 powder is expected to find potential applications in the field of magneto-optical modulation and relevant devices., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Engineering phosphorus heteroatoms into the plane of ultrathin MoS2 nanosheets is realized via a facile thermolytical process. The doping of low-electronegative P atoms generates an extra ORR activity with four-electron selectivity, manifesting seven-fold current increase as well as 160 mV positive shift in both onset and half-wave potentials.

A family of heteronuclear metal organic frameworks (MOFs) using lanthanide and transition metal ion based on a rigid ligand of substituted imidazoledicarboxylic acid, namely, {[Ln2Zn2 (μ3-Hmimda)2 (μ3-mimda)2·4H2O]n·mn H2O}, Ln = Nd, m = 2 (1), Ln = Ho, m = 3 (2), Ln = Er, m = 2 (3), Ln = Yb, m = 3 (4), [Tb2Co2(μ3-Hmimda)2 (μ3-mimda)2·4H2O]n·2nH2O} (5) and [Dy2Co2 (μ3-Hmimda)2 (μ3-mimda)2·4H2O]n·nH2O} (6), (H3mimda = 1H-2-methyl-4,5-imidazole-dicarboxylic acid), have been developed and characterized. All the complexes (except for a little disparity for 1) are isostructural, and all crystallize in the monoclinic system. They possess an extended reticular-like porous structure constructed from corrugated 2D layers. Direct current (dc) magnetic susceptibility measurements for 1-5 indicated depopulation of the Stark components at low temperature and/or possible weak anti-ferromagnetic interactions within hetero-nuclear MOFs. Alternating current (ac) susceptibility studies reveal that the Dy(III)-Co(II) complex exhibits both possible ferromagnetic couplings and frequency-dependent out-of-phase signals, behaviour of single-ion magnet nature. Fluorescence properties of series complexes both in near-infrared (NIR) and visible regions have been comparatively studied.

A new zinc compound, together with a corresponding series of Zn-4f heterometallic coordination polymers, namely, [Zn(H2PBDA)(PBDA)]n (1), {[Ln2(PBDA)2·2H2O] [Zn2(PBDA)2Cl2]}n [H2PBDA = 3-(pyridin-3-yl-oxy) benzene-1,2-dicarboxylic acid, and Ln = Pr(2), Nd(3), Eu(4), Gd(5), Dy(6), Ho(7), Er(8)] have been hydrothermally synthesized and characterized systematically. Polymers 2-8 feature two-dimensional (2D) 4,4 networks, containing the original 1D heterometallic double stranded chains composed of [Ln2Zn2(PBDA)2] entities. The extensive hydrogen bonding and π-π stacking interactions were observed to stabilize the extended architectures. The luminescence emission spectra of the polymers vary depending on the lanthanide(III) ion present. Informative magnetic susceptibility measurements show that the same carboxylate bridging fashion of the PBDA ligand results in the different magnetic properties occurring within the heterometallic coordination polymers. In addition, polymer 6 exhibits an interesting slow magnetic relaxation behavior at lower temperatures.