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In this work, the effects of a chitosan-based derivative (CSA), DOPO and CSA-DOPO additives on the flammable properties of EP composites were systematically studied, where CSA was synthesized by a facile condensation between chitosan (CS) and 9-anthralaldehyde and. DOPO was 9, 10-dihydro-9-oxa-10- phosphaphenanthreene-10-oxide. The mass ratio of CS and 9-anthralaldehyde in CSA was determined by elemental analysis and theoretical calculation, which matched well with each other. Under the 8% addition in EP, EP/2.66%/5.34%DOPO sample was the only one, which passed the UL-94 rating and exhibited the highest LOI value of 36.4%. Compared with EP, the cone calorimeter test (CC) showed that the total smoke emission value and the peak heat release rate of the CSA and DOPO modified EP decreased 36.0% and 61.9%, respectively, and the residual char amount increased by 151%. The possible flame retardant mechanism of CSA/DOPO towards EP was proposed according to the results of the real time FTIR spectra at different pyrolysis temperatures, cone calorimeter and Py-GC/MS analysis for EP and EP/2.66%CSA/5.34%DOPO samples, and Raman spectra and XPS for their char residues. Moreover, the incorporation of CSA/DOPO effectively improved the mechanical properties, especially, the flexural strength was increased by 52.3%. It was proposed that CSA/DOPO plays roles in both vapor and condensed phases, and the synergistic effect of CSA and DOPO significantly improve the flame retardancy and mechanical strength of EP.

This work proposed to prepare solid acid from phosphorus tailings and successfully convert Dioscorea zingiberensis C.H. Wright (DZW) into diosgenin from the perspective of solid waste resource reuse and clean production. The results showed that SiO2–SO3H solid acid could catalyze the production of diosgenin from total saponins under solvothermal reaction conditions. In addition, the parameters of a single factor, such as the amount of SiO2–SO3H, solvent volume, reaction temperature, and reaction time, were optimized to confirm the optimal range of reaction conditions, and the optimal process conditions were determined by the response surface method. The yield of diosgenin was 2.45 ± 0.17% under the optimum conditions, and the yield of diosgenin was increased by 12.90% compared with the traditional acid hydrolysis process. Except the relatively higher catalytic activity, the alcoholysis approach for the production of diosgenin has no waste liquid to discharge. The products were analyzed by high-performance liquid chromatography-mass spectrometry, and the pathway to convert total saponins into diosgenin under SiO2–SO3H has been proposed. Moreover, the adopted catalyst can be prepared with very low cost from phosphorus tailings. Considering the obvious superiorities, the alcoholysis approach in this work could be a promising strategy for green production of diosgenin as well as a possible utilization pathway of phosphorus tailings.

Thanks to the unique structure and properties of MOFs, a well-designed novel hollow ZnO/Mn-ZIF-67 composite photocatalyst was synthesized by a facile sonocrystallization approach successfully. The hollow ZnO/Mn-ZIF-67 composites exhibited higher photocatalytic activity in degrading Bismarck brown R than pure hollow ZnO spheres and Mn-ZIF-67. The optimal ZnO/Mn0.5-ZIF-67 showed the highest catalytic activity with 89.5% Bismarck brown R removal within 100 min. The improved photocatalytic activity of the composites could be mainly attributed to effective photogenerated charge separation and transfer through the coupled Z-scheme heterojunction between hollow ZnO spheres and Mn-ZIF-67. The composite photocatalyst exhibited obviously good stability and recyclability after recycling 4 times. Finally, a possible Z-scheme electron transfer mechanism was proposed based on the active radical trapping experiments and ESR which could explain the improved photocatalytic performance of the photocatalytic system. This work provides a promising approach to construct a direct Z-scheme heterojunction for the degradation of environmental pollutants.

Due to the unique structure and performance of COFs, a new well-designed nano-LZU1@WO3 composite photocatalyst was successfully synthesized through a simple hydrothermal method. The nano-LZU1@WO3 composite material shows higher photocatalytic activity than pure WO3 and LZU1 in the degradation of BBR. The best LZU10.44@WO3 showed the highest catalytic activity, removing 97.7% of BBR within 90 minutes and 97.4% MB in 110 minutes. The improved photocatalytic activity of the composite material is mainly attributed to the effective photo-generated charge separation and Z-type heterojunction transfer through the coupling between WO3 and LZU1. The composite photocatalyst showed obvious good stability and recyclability after 4 cycles. Finally, based on the active radical capture experiment and ESR, a possible Z-scheme electron transfer mechanism is proposed, which can explain the improved photocatalytic performance of the photocatalytic system. Moreover, the best hydrogen evolution for LZU10.5@WO3 reached 6133.2 μmol h−1 g−1, which is 386 times and 1.6 times that of pure WO3 and pure LZU1, respectively. We hope this work will provide a timely reference for the advancement of COF-based heterojunctions towards environmental pollutants and useful insights for future energy technologies beyond water electrolysis.

A novel [DyIIINaI] complex, [DyNa(L)2(MeOH)]·MeOH (1, H2L = N,N′-bis(2-oxy-3-methoxybenzylidene)-1,2-phenylenediamine), and a zigzag 1D chain based on the [DyIIINaI2] subunit, [DyNa2(L)2(NO3)]n·MeOH (2), were obtained by employing a multidentate Schiff base ligand H2L reacting with Dy(NO3)3·5H2O, NaN3 and NMe4OH·5H2O in MeOH or reacting with Dy(NO3)3·5H2O and NaOH in methanol. Structural analyses revealed that the DyIII in 1 and 2 is sandwiched between two L2− ligands, namely, the DyIII ion was coordinated by four phenoxido O and four amine N atoms from two L2− ligands. SHAPE software calculations and structural analysis indicated that the coordination geometry of DyIII in 1 and 2 is a distorted square antiprism (D4d), but the distortion degree of DyIII in 1 was smaller than that in 2. Additionally, in 1, one NaI is located on one of the N2O2 planes, and the NaI is coordinated by three phenoxido O and three methoxy O atoms from two L2− ligands and one coordinated MeOH molecule. However, in 2, two NaI ions are located on each of the N2O2 planes, in which the coordination environment of each NaI is completed by three phenoxido O atoms, three methoxy O atoms and two O atoms from one NO3− ion. Moreover, the [DyIIINaI2] units are linked into a zigzag 1D chain by nitrate anions. ac magnetic susceptibility measurements revealed that both complexes 1 and 2 exhibit field-induced single ion magnet behavior under a 1000 Oe dc field, with values of the effective energy barrier (Ueff) of 65.33(1) K for 1 and 84.23(1) K for 2. Interestingly, the Ueff values of 1 and 2 are both higher than the corresponding value of 40.1 K for a reported complex with the coordination geometry of a bicapped triangular prism. The moderate SIM performance of 1 and 2 in the Dy(III)-based SIMs with a SAP coordination geometry could be ascribed to the compressed SAP coordination environment of DyIII ions, dipole–dipole interactions and the deviation of the anisotropic axes from the S8 axis.

Two coordination polymers, {[Cu3(tib)4(NO3)4(H2O)]·2NO3·2.96H2O}n (1) and {[Ni(tib)2]·2NO3}n (2), were synthesized by a solvothermal reaction using a flexible tripodal ligand, 1,3,5-tris(imidazol-1-ylmethyl)benzene (TIB), and metal salts; the polymers were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectra. The two complexes exhibited excellent active performance for photodegradation of tetracycline (TC) and photocatalytic hydrogen evolution under visible light. Control experiments revealed clearly that the pH value plays an important role in TC degradation, especially in alkaline solution; 93.21% of tetracycline was degraded by complex 1 within 60 min. In addition, using a Pt cocatalyst, the visible-light-driven photocatalytic H2 evolution rate of complex 2 reached 681.66 μmol h−1 g−1. Moreover, the photocatalysts can remain stable and retain high photocatalytic activity after several cycles of reuse. These MOF-based photocatalysts will provide new efforts for environmental purification and hydrogen evolution.

Heterostructure construction in photocatalysts is an effective method to improve their catalytic activity because of the remarkable role that the heterostructure plays in charge separation. In this study, a novel photocatalyst, a ZnO/ZIF-9 heterojunction, was prepared by a facile sonocrystallization approach. The photocatalytic results showed that ZnO/ZIF-9 heterostructures with 50 wt% ZIF-9 reached the maximum degradation efficiency (around 87.7%) for TC within 1 h. The improved photocatalytic activity of the composites is primarily due to the formation of the heterojunction between ZnO and ZIF-9; therefore, the separation efficiency of electron–hole pairs can be effectively enhanced during the photocatalytic reaction. Finally, a possible mechanism to explain the improved photocatalytic performance of the photocatalytic system was proposed. More importantly, ZnO/ZIF0.5 possesses good stability and reusability after recycling four times. This study demonstrates a promising and facile approach to construct a high efficiency heterojunction photocatalyst for the elimination of environmental pollutants.

Development of highly efficient photocatalysts for photocatalysis research has been a hot research area in recent years. Herein, the phosphate-based metal organic framework (MOF)/P–TiO2 hybrid composites (MOFx/P–TiO2) were first synthesized using the phosphonate-based MOF [Cd(H2L)]n (H4L = 2,5-dimethylbenzene-1,4-diylbis(methylene)diphosphonic acid) and phosphated mesoporous TiO2 beads (P–TiO2) using a versatile step-by-step self-assembly strategy for environmental remediation. The results showed that the Cd-MOF loading content in the MOFx/P–TiO2 has an important influence on the degradation of pollutants, and the hybrid materials could significantly enhance the photocatalytic activity for the photo-oxidative degradation of RhB (97.6% in 25 min over MOF1.5/P–TiO2) and the reduction of Cr(VI) (96.1% in 60 min over MOF0.5/P–TiO2) in comparison with the single-component Cd-MOF or P–TiO2. The enhancement of the photocatalytic activity of MOFx/P–TiO2 could be mainly attributed to: (i) the strong light absorption capacity, and (ii) the effective photogenerated charge separation and transfer through the coupled heterojunction interfaces of P–TiO2 and Cd-MOF. Furthermore, the results verified that the matched band structure of P–TiO2 and Cd-MOF could induce a superfast Z-scheme interfacial charge transfer path. Therefore, a reasonable Z-scheme charge transfer mechanism was proposed based on the active species trapping experiments and the results of electron spin resonance (ESR). More importantly, MOF0.5/P–TiO2 and MOF1.0/P–TiO2 possess a good stability and reusability after recycling five times owing to the high chemical stability of the Cd-MOF, P–TiO2 and heterojunctions. The present work provides a promising approach to construct direct Z-scheme porous heterojunctions for elimination of environmental pollutants.

A pentanuclear heterometallic complex [MnIII4DyIII(HL)4{(py)2CO2}2Cl2](OH) (1, H3L = 2-((2-hydroxybenzylidene)amino)propane-1,3-diol, (py)2C(OH)2 = the gem-diol form of 2,2′-dipyridyl ketone) and a one-dimensional (1D) chain [Mn2Dy(HL)2(hmp)2(CH3COO)2N3]n·H2O (2, Hhmp = 2-pyridinemethanol) were obtained by the assemblies of the H3L ligand and Dy(NO3)3·5H2O with MnCl2·4H2O and 2,2′-dipyridyl ketone or with manganese acetate and 2-pyridinemethanol under different alkaline solutions. In 1, four MnIII ions formed an irregular tetrahedron, in which four MnIII ions were linked with the central DyIII by eight O atoms from HL2− or from (py)2CO22− ligands. In 2, one DyIII and two MnIII formed a [Mn2Dy] unit, in which the metal ions were bridged by one N3− ion and by four O atoms of two HL2− and two hmp− ligands, and then these [Mn2Dy] units were further linked by the O atoms from HL2− ligands and formed a 1D zigzag chain. Magnetic studies indicated that both complexes exhibit slow relaxation behavior, with the effective energy barriers of 7.9 K and 9.6(0) K for 1 and 2, respectively, which might represent new members for the rarely polynuclear Mn–Dy single molecule magnets. The orientations of the easy magnetization axes of DyIII ions in 1 and 2 were estimated by the Magellan program, indicating that the easy axes of DyIII in 1 are nearly directed to C16 and C47 from (py)2CO22− ligands, while the axis in 2 is almost directed to O5 (from the acetate ligand).

A new Dy Na complex [DyIIINaI(CH3CO2)2(DMF)3(H6C8A)]·4DMF (1, DMF = N,N-dimethylformamide, H8C8A = p-tert-butylcalix[8]arene) was obtained and it was characterized by elemental analyses, IR spectroscopy, single-crystal X-ray diffraction analyses, PXRD and magnetic properties. In 1, one DyIII and one NaIII were linked by two O atoms from two CH3CO2− and the two metal ions were enclosed into a H8C8A. The remaining coordination sites of the DyIII and NaI ions were occupied by three O atoms from three DMF coordinated molecules. The DyIII ion in 1 adopts eight coordinate with a triangular dodecahedron. Magnetic property studies indicated complex 1 show slow magnetic relaxation behavior under 1000 Oe applied dc field. Additionally, the orientation of the anisotropy axis for the DyIII in 1 was estimated by Magellan program and the anisotropic axis is aligned along Dy1-O2 bond with an angle of 12.608°.

The photocatalytic hydrogen evolution on inorganic semiconductors has been studied for several decades. However, the conversion efficiency of solar energy is still poor caused by the recombination of photo-generated electron-hole pairs. Semiconductors - metal organic frameworks (MOFs) hybrid photocatalysts are being regarded as promising candidates due to large surface area and porosity. Here we reported the coordinative integration of a composite material with efficient capacity of H2 evolution driven by solar light, namely TiO2@ZIF-8, made up of titanium dioxide hollow nanospheres (TiO2 HNPs) externally decorated with zeolitic imidazolate framework-8 (ZIF-8) via a facile sonochemical route. The resulting composite demonstrates the high dispersion of ZIF-8 on the surface of TiO2 HNPs and this kind of close connection makes for an efficient photocatalyst through the synergistic effect. Up to 50.89% of apparent quantum efficiency (AQE), the hybrid double-shell HNPs exhibits 3.5 times higher H2 evolution rate (HER) than the bare TiO2 HNPs under solar light and shows good stability and recyclability. It is further proposed by photoluminescence spectra and optoelectronic measurement that the remarkably enhanced photocatalytic activity of TiO2@ZIF-8 is not only attributed to the efficient charge separation with electron injection from ZIF-8 to TiO2 HNPs, but also more active reaction sites provided by cavity structure of ZIF-8. Overall, this work exemplifies that surface engineering of semiconductors with MOFs is a great strategy to achieve advanced photocatalytic performance for solar energy conversion.

Porous CuO/Cu2O heterostructure was successfully synthesized through a metal organic frameworks (MOFs)-assisted template method. Tunable production of pure phase CuO and Cu2O could be achieved by regulating the coordination environment of copper. The copper oxides inherited the polyhedral morphology from the Cu MOFs and possessed higher surface area and larger pore volume. Compared with pure CuO and Cu2O, heterostructured CuO/Cu2O displayed remarkably enhanced NH3-SCR de-NOx activity and N2 selectivity in a low temperature range of 170–220 °C. Systematical in situ DRIFT characterization revealed that the NH3-SCR of NOx over CuO/Cu2O heterostructure followed Eley-Rideal (E-R) mechanism, which was greatly improved by the abundant Lewis acid sites, improved O2 adsorption and the synergistic effect between Cu+ and Cu2+. In addition, CuO/Cu2O heterostructure exhibited excellent H2O, SO2, alkali metals, and hydrocarbon durability, indicating its potential use in industrial NH3-SCR of NOx.

Six new transition metal phosphonates, [Cd(H2L)(H2O)]n (1), [Cd2(H2L)2(H2O)]n (2), [Cd4(H2bmt)2(H2O)]n (3), {[Cd2(H4bmt)2(2, 2′-bipy)2]·4H2O} (4), [Zn(H4bmt)(2, 2′-bipy)]n (5) and [Zn3(bmt)(4, 4′-bipy)2]n (6), H4L = (benzylazanediyl)bis(methylene)-diphosphonicacid,H6bmt = (benzene-1,3,5-triyltris(methylene))triphosphonic acid, have been synthesized by H4L or H6bmt as well as auxiliary ligands under hydrothermal conditions and characterized by elemental analysis, IR, XRD and single-crystal X-ray diffraction. Structural analysis indicates that complexes 1–6 feature 0D-3D structures. The introduction of auxiliary ligands including 4, 4′-Vinylenedipyridine, 4-Cyanopyridine, 4, 4′-bipy, 2, 2′-bipy and H6TTHA (1,3,5-triazine-2,4,6-triamine hexaacetic acid) increases the crystallinity and controls the dimensionality of the final complexes. The fluorescence emission properties of 1–6 and the free ligands were investigated in the solid state at room temperature. Moreover, the fluorescence lifetime (τ) and quantum yield (Φf) were measured to further characterize the fluorescence properties. The results are compared to illustrate the influence of the auxiliary ligands and structure difference on the fluorescence properties.

Four tetranuclear 3d–4f complexes, namely [Fe2Ln2(L)2(teaH)2(Cl)2](NO3)2·4CH3CN (H2L = N1,N3-bis(3-methoxysalicylidene)diethylenetriamine, teaH3 = triethanolamine, Ln = Dy for 1 and Ln = Gd for 1′) and [Co2Ln2(L)2(pdm)2(CH3COO)2(CH3OH)2](NO3)2·xCH3OH·yH2O (pdmH2 = 2,6-pyridinedimethanol, Ln = Dy, x = 5 and y = 2.5 for 2 and Ln = Gd, x = 6 and y = 1.5 for 2′), have been reported. Two FeIII and two DyIII in 1 formed a zigzag Fe1–Dy1–Dy1a–Fe1a arrangement with a Fe1–Dy1–Dy1a angle of 105.328(3)°. However, in contrast to 1, two CoIII and two DyIII ions in 2 formed a more linear Co1–Dy1–Dy1a–Co1a arrangement with a Co1–Dy1–Dy1a angle of 141.86(2)°. Additionally, two DyIII ions in 1 are eight-coordinated with a triangular dodecahedron geometry, while two DyIII ions in 2 adopt nine-coordination with a muffin geometry. Magnetic studies revealed slow magnetic relaxation behavior for 1, with an energy barrier Ea of 6.9 K. For 2, single molecule magnet behavior was presented under a zero dc field with an effective energy barrier Ueff of 64.0(9) K. Ab initio calculations for 1 and 2 indicate that compared to 2, complex 1 has a larger transversal magnetic moment of its ground Kramers doublets (KD) and a larger value of the tunnelling parameter (Δt) for the exchanged coupled ground state, which may result in poor single molecule magnet behavior for 1.

Three novel metal–organic frameworks (MOFs) photocatalysts with different structures [Cd(4-Hptz)2(H2O)2Cl2](4-Hptz = 4-(1H-tetrazol-5-yl)-pyridine) (1), [Cu(btx)2(ClO4)2]n(btx = 1,4-bis(triazol-1-ylmethyl)benzene) (2), and [Cu(btx)(ClO4)]n (3) have been synthesized by solvothermal reaction successfully. All samples were characterized by X-ray, FT-IR, XPS and UV–Vis diffuse reflectance spectra. The photocatalytic properties were investigated by degradation of methylene blue (MB) dye and reduction of Cr(VI) to Cr(III) in aqueous solution under UV light. Control experiments show that the pH value is vital for Cr(VI) reduction, and meanwhile, the use of hole scavenger of methanol promotes the photocatalytic reduction significantly. It has been also demonstrated that photocatalysts 1 and 2 are efficient for MB degradation. The cyclic experiments indicated three photocatalysts are stable and reusable, enabling them to be the potential candidate in environment governance.

Four chair-like hexanuclear Fe-Ln complexes containing mixed organic ligands, namely, [Fe4Ln2{(py)2CO2}4(pdm)2(NO3)2(H2O)2Cl4]·xCH3CN·yH2O (Ln = GdIII (1, x = 1, y = 0), DyIII (2, x = 1, y = 1), HoIII (3, x = 0, y = 2), and ErIII (4, x = 1, y = 3); (py)2CO2H2 = the gem-diol form of di-2-pyridyl ketone and pdmH2 = 2,6-pyridinedimethanol) have been obtained by employing di-2-pyridyl ketone and 2,6-pyridinedimethanol reacting with FeCl3 and Ln(NO3)3 in MeCN. The structures of 1-4 are similar to each other except for the number of lattice solvent molecules. Four FeIII and two LnIII in these complexes comprise a chair-like core with the "body" constructed by four FeIII ions and the "end" constructed by two LnIII ions. Among the four compounds, 2 shows field-induced single molecule magnet behavior as revealed by ac magnetic susceptibility studies, with the effective energy barrier and the pre-exponential factor of 22.07 K and 8.44 × 10-7 s, respectively. Ab initio calculations indicated that, among 2_Dy, 3_Ho and 4_Er fragments, the energy gap between the lowest two spin-orbit states for 2_Dy is the largest, while the tunneling gap for 2 is the smallest. These might be the reasons for complex 2 exhibiting SMM behavior. Additionally, the orientations of the magnetic anisotropy of DyIII in 2 were obtained by electrostatic calculations and ab initio calculations, both indicating that the directions of the main magnetic axis of Dy1 ions are almost aligned along Dy1-O5 (O5 from the pdm2- ligand).

In this work, we report the syntheses, crystal structures and magnetic properties of three novel Zn–Ln mixed metal complexes, namely [Zn4Dy2(L1)2(L2)2(N3)2]Cl2·2H2O (1), [Zn4Tb2(L1)2(L2)2(Cl)2][ZnN3Cl3]·2H2O (2), and [Zn4Gd2(L1)2(L2)2(Cl)2][ZnN3Cl3]·2H2O (3), in which L12− and L23− were formed from the ligand L [L = N1,N3-bis(3-methoxysalicylidene)diethylenetriamine] through in situ reactions. Interestingly, carbon dioxide in air was absorbed in the process of forming carbamate ligand L23−; this can be ascribed to the insertion of CO2 into M–N amide bonds. Moreover, 1 and 2 represent the first series of 3d–4f SMMs containing carbamate ligands by fixation of CO2 in air. Single-crystal X-ray diffraction analyses reveal that the crystal structures of 1 and 2 are anion-dependent, i.e., the apical positions of the two ZnII ions in 1 and 2 are occupied by an N atom of N3− and by Cl−, respectively. However, the topologies of 2 and 3 are similar. Two ZnII ions and one LnIII (Ln = Dy (1), Tb (2) and Gd (3)) form nearly linear trinuclear [Zn2Ln] units which are double-bridged by two L23− ligands. Magnetic studies reveal that two complexes show single molecule magnet behavior under a direct current (dc) field, with effective energy barriers (Ueff) of 30.66(5) K for 1 and 8.87(3) K for 2. Ab initio calculations reveal that the DyIII ions in 1 and the TbIII ions in 2 are axial in nature; however, a difference in the tunnel splitting of 1 and 2 leads to variation in the magnetization blockades of the two complexes. Theoretical calculations also indicate that the directions of the main magnetic axes severely deviate from the coordination atoms of the first spheres of DyIII and TbIII in 1 and 2; thus further results in poor SMM behavior of the two complexes.

Two novel transition metal compounds, [Ni(4,4'-bipyH)2(H2O)4]·2(H4bmt)·9H2O (1) and [Co(4,4'-bipy)(H2O)4][Co(4,4'-bipyH)2(H2O)4]·2(H3bmt)·6H2O (2), have been synthesized. They possess continuous H-bond networks and high-density [PO3] groups, which give conductivity values in the order of 10-3 S cm-1 in a wide temperature range and 98% relative humidity.

To modulate the molecular symmetry of tetrahedral Dy4 complexes, in this paper, we reported two complexes based on a Dy4 or Dy2Fe2 tetrahedral unit, namely, [Dy4(NO3)(HL)4{(py)2C(OH)O}2](OH)·6CH3CN·0.5H2O (1, H3L = 2-((2-hydroxybenzylidene)amino) propane-1,3-diol, (py)2C(OH)2 = the gem-diol form of di-2-pyridyl ketone) and [Fe4Dy2(μ4-O)(HL)3{(py)2CO2}{(py)2C(OH)O}{(py)2C(OCH3)O}(L′)Cl3]Cl·6CH3CN·3.5H2O (2, H2L′ = 2-amino-1,3-propanediol). In 1, each of the four sides of the Dy4 tetrahedron was constructed from one O atom of one (py)2C(OH)O− ligand and one O atom of one HL12− ligand, one side was constructed from two O atoms of two (py)2C(OH)O− ligands, and the remaining side was not constructed from organic ligands. Consequently, NO3− in 1 adopts an unprecedented η4, η1, η1, μ4 coordination mode, in which one O atom (O17) linked with four DyIII and each of another two O atoms further coordinated with a DyIII ion. For 2, the tetrahedral unit was composed of two DyIII ions and two FeIII ions, and each of the two DyIII ions is further linked with an FeIII ion. Slow relaxation behavior was observed for both complexes, with an energy barrier of 8.73 K for 1 under a zero dc field and 13.80 K for 2 under a 1500 Oe dc field, respectively. The orientations of the magnetic anisotropy of DyIII in 1 and 2 were calculated by the Magellan program, indicating that the easy magnetization axes of the four DyIII ions in 1 were not directed to O17, while the axes in 2 are nearly parallel to each other.

A coordination polymer, {[Co(tib)2]·SO4}n, has been synthesized by a solvothermal reaction using the flexible tripodal ligand 1,3,5-tris(imidazol-1-ylmethyl)benzene (TIB) with metal salts, and has been characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and UV-vis diffuse reflectance spectroscopy. The photocatalytic properties of the complex were investigated by the photodegradation of methylene blue (MB) dye under visible light. Control experiments clearly revealed that the pH of the solution plays an important role in MB degradation, especially when in alkaline solution. {[Co(tib)2]·SO4}n has excellent degradation ability of MB, and 150 mL MB (10 mg L−1) could be fully photodegraded in 25 min with a high pseudo-first-order rate constant. The reaction mechanism of photocatalysis showed that O2˙− and h+ are the main active substances, based on active species trapping experiments and ESR. The excellent photocatalytic activity is mainly attributed to the strong light harvesting and high reactivity of electrons and holes. Moreover, liquid chromatography-mass spectrometry (LC-MS) was used to analyze the catalytic process, effectively revealing the photodegradation mechanism of MB. Recycling experiments demonstrated that the photocatalyst is reusable and stable. This MOF-based photocatalyst will, therefore, provide new efforts towards environmental purification.

A novel DyIII-NaI one-dimensional chain, namely [DyIIINaI(L)(CH3CO2)2]n·2CH3CN (1, H2L = N1,N3‑bis(3‑methoxysalicylidene)diethylenetriamine), was synthesized by treating H2L, di-2-pyridyl ketone (dpk), and NaHCO3 with Dy(CH3CO2)2·6H2O in acetonitrile. Complex 1 was characterized by elemental analyses, IR spectroscopy, single-crystal X-ray diffraction analyses and magnetic properties. Structural analyses revealed that 1 consists of a neutral one-dimensional (1D) chain. In each [DyNa] unit, one DyIII and one NaI ions are bridged by two phenoxido O atoms from one L2− ligand and one carboxyl O atom from one CH3CO2−. Moreover, the [DyNa] units were further connected by two carboxyl O atoms from another CH3CO2−. The magnetic studies revealed that 1 exhibits the field-induced single molecule magnet behavior with an effective energy of 13.21 K. The orientation of the anisotropy axes for the DyIII in 1 was estimated by Magellan program, indicating that the directionality of the anisotropic axes is almost collinear to the Dy1-O8 bond, with an angle of 3.085°.

Four new complexes of Robson-type macrocycles, [CuH(L1)]2(ClO4)2(H2O)2 (1), [CuH(L2)] ClO4 (2), [Cu H(L3)]2(ClO4)2 (3), [Cu H(L4)]2(ClO4)2(CH3CH2OH)2(CH3CN)2(4) and two reported Robson-type macrocycles polymers {[CuL5](H2O)2}n(5), {[MnL5](H2O)2}n (6) were obtained. The ligands (H2L1, H2L2, H2L3) are the products from the condensation between bata and N,N′-bis(3-formyl-5-X-salicylimine)-1,2-ethylenediimine (X = CH3, Cl, F), respectively. Ligands H2L4 and H2L5 are the products of N,N′-bis(3-formyl-5-methylsalicylimine)-1,2-propylenediimineand condensation with bafa and bapa, respectively. All the metal ions have unsaturated coordinated sites, which are available for NO binding. The binding of the complexes with NO molecules have been confirmed by UV–Vis spectrophotometry. The binding constants were calculated to be 1.28 × 103 M−1, 8.9 × 102 M−1, 7.7 × 103 M−1, 1.2 × 103 M−1, 1.2 × 103 M−1, 1.3 × 103 M−1 for 1, 2, 3, 4, 5 and 6, respectively. The control experiments revealed there was non-reversible binding of NO, which can be ascribed to specially coordination environment of the central ions. Moreover, the interactions of the complexes with calf thymus DNA (CT-DNA) have been measured by agarose gel electrophoresis, and unobvious DNA cleavage ability of complexes 1, 3 and 4 indicating no damage to DNA. The results reveal that complexes 1, 3 and 4 can be served as potential NO scavengers.

New magnesium phosphonates Mg(H 2 L) 3 1 (H 4 L = 2,5-dimethylbenzene-1,4 -diylbis(methylene)diphosphonic acid) and Ca(H 2 L)·2H 2 O 2 have been hydrothermally synthesized from H 4 L and the corresponding metal salts. Complex 1 and 2 have been characterized by IR, powder and single-crystal X-ray diffraction methods. Complex 1 crystallizes in trigonal space group R-3c and complex 2 belongs to the triclinic space group. The complexes both form two-dimensional (2D) network structure and show three-dimensional (3D) network through hydrogen bonds. Thermal stability of complex 1 and 2 have also been investigated. CCDC: 1534599 for 1 ; 1536423 for 2 .

The synthesis, crystal structures, and magnetic properties of a nonanuclear dysprosium complex [Dy9(μ3-OH)8(μ4-OH)2(N3)8{(py)2C(OCH3)O}8](OH)·4H2O (1, (py)2C(OCH3)OH = the hemiacetal form of di-2-pyridyl ketone) and a tetranuclear dysprosium complex [Dy4(μ4-O)(μ-N3)2(μ-OCH3)2(L)4](OH)2·3.5CH3OH (2, HL = 2-(benzothiazol-2-yl-hydrazonomethyl)-6-methoxyphenol) have been prepared and structural characterization. Nine DyIII ions in 1 form a sandglass with the eight DyIII atoms at the apexes and one DyIII ion located at the center of a square antiprism formed by eight DyIII ions, while four DyIII ions in 2 form an irregular tetrahedron. Complexes 1 and 2 have been investigated by direct current (dc) and alternating current (ac) susceptibility measurements. The ac susceptibility studies revealed that complexes 1 and 2 exhibit slow magnetic relaxation. Moreover, complex 2 shows two-step thermal magnetic relaxation with their energy barriers of about 15 K and 2.68 K, respectively. The orientations of the magnetic anisotropy of DyIII ions in 1 and 2 were also estimated by electrostatic calculations.

Two 3D metal–organic frameworks (MOFs) with different structures, [Cu(4,4′-bipy)Cl]n (1) and [Co(4,4′-bipy)·(HCOO)2]n (2), were synthesized by means of a hydrothermal method using a typical ligand (4,4′-bipyridine), and characterized by elemental analyses, thermal analyses and single crystal X-ray diffraction. As MOF materials, the two complexes showed active performance for the photodegradation of methylene blue (MB) dye under visible light. MB degradation over the two MOF-based photocatalysts follows first-order kinetics. The addition of an H2O2 electron acceptor can markedly enhance the photocatalytic MB degradation performance via a ligand-to-metal charge transfer mechanism, especially in complex 1. Complex 1 is better than complex 2 in MB photodegradation performance under the same conditions. Moreover, complex 1 showed a stable activity for MB degradation after four consecutive usages. Owing to the advantages of the visible light response, stable structure, low cost and high yield, these MOF-based photocatalysts will facilitate new efforts in environmental purification.

Two 1-D luminescent metal-organic frameworks with identical structures, {[Mn(BBPTZ)2(MeCN)2]·(ClO4)2}n (1) and {[Zn(BBPTZ)2(MeCN)2]·(MeCN)2·(ClO4)2}n (2), have been synthesized under solvent diffusion evaporation and characterized by elemental analyses, thermal analyses and single-crystal X-ray diffraction. Both complexes crystallize in the monoclinic system, space group C2/c with six-coordinate M(II). Thermal decompositions of the complexes have been studied using thermogravimetric analyses (TGA). The complexes exhibit a significant fluorescence quenching effect to Fe3+ in acetonitrile solution. The LoDs (Limit of Detection) of the complexes to Fe3+ are 2.59 × 10−8 M and 1.57 × 10−8 M for 1 and 2, respectively. The complexes could be applied to efficient chemosensor for Fe3+ detection.

Four chair-like hexanuclear Fe-Ln complexes containing mixed organic ligands, namely, [Fe

Four tetranuclear 3d-4f complexes, namely [Fe

The magnetic solid acid, Fe3O4@PEI@SO3H, was synthesized and used as a catalyst to transfer steroid saponins into diosgenin in an alcoholysis approach. The results showed that the magnetic solid acid greatly improved the alcoholysis efficiency for extraction diosgenin from steriod saponins. To optimize the parameters for alcoholysis, such as the mass of the solid acid, solvent volume, the reaction temperature and time, single factor experiments as well as response surface experiment have been performed. Under the optimal conditions, the diosgenin yield obtained by alcoholysis is higher than that of the traditional inorganic acid hydrolysis. And it worth to mention that no waste liquid is discharged. The catalyst is very stable and can be used for three times without obvious mass loss and activity decrease, indicating that the technology of extracting diosgenin from Dioscorea zingiberensis C.H. Wright tuber has a broad prospect in industrial application.

Since 1993, single molecule magnets (SMMs) have received a wide attention for their potential applications in high-density information storage device, quantum computer and spintronics. Particularly, since a CuII2TbII2 complex was found to possess slow magnetic relaxation behavior in 2004, 3d-4f heterometallic complexes are being investigated because they can provide the moderate magnetic couplings between 3d and 4f ions and can provide the significant single-ion magnetic anisotropies of 4f ions, which are in favor of improving SMM performance. Choosing an appropriate organic ligand with ligating atoms linked with 3d and 4f ions simultaneously is a key to synthesize 3d-4f complexes. However, synthesizing 3d-4f complexes by employing two kinds of non-carboxylate organic ligands has received little attention. We believe that the metal core topologies, the magnetic couplings, coordination geometries of 4f ions and the magnetic relaxation behavior of the 3d-4f complexes could be modulated by employing several types of non-carboxylate organic ligands due to the large steric effects between the non-carboxylate organic ligands. Based on the considerations, in recent years, we concentrated on the investigations of the 3d-4f complexes with several types of non-carboxylate organic ligands. In this review, we will present a summary of the 3d-4f complexes reported by us. The studies indicate that the metal core topologies and the magnetic couplings of the obtained 3d-4f complexes were indeed regulated, and most of the complexes possess SMM behavior. Finally, we provided some suggestions to further improve the SMM performance of the 3d-4f complexes.

Diosgenin is an important intermediate of steroid hormone drugs, green production of diosgenin with high yield is a key research issue. In this study, a convenient, efficient, and eco-friendly approach was developed to produce diosgenin from saponins in D. zingiberensis C. H. Wright (Curcuma longa L) using a magnetic solid acid. Fe3O4@SiO2-Pr-S-SO3H is a heterogeneous catalyst and was obtained by loading 3-(mercaptopropyl) trimethoxysilane on the surface of Fe3O4@SiO2, followed by sulfonation with chlorosulfonic acid. The magnetic solid acid catalyst was fully characterized by Fourier Transform-Infrared (FT-IR) spectra, thermo gravimetric analysis (TGA), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and X-ray photoelectron spectroscopy (XPS), scanning electron microscope(SEM), transmission electron microscope (TEM), NH3-TPD, elemental mapping analysis. The effects of single factors, such as the solid acid mass, alcoholysis temperature, extraction time, and solvent volume on the diosgenin yield were analyzed. The extraction parameters for diosgenin were optimized by response surface methodology (RSM). The optimized values for the solid acid mass, solvent volume, extraction time, and temperature were 0.22 g, 7.8 mL, 7.4 h, and 100 °C, respectively. Under the optimized conditions, the maximum yield of diosgenin was 19.15 %. The solid acid reported in this work exhibited higher catalytic activity at a smaller dosage than traditional sulfuric acid and other solid acids. The alcoholysis products were identified by high-performance liquid chromatography-mass spectrometry (HPLC-MS). Alcoholysis catalysed by an as-prepared magnetic solid acid is clearly superior in terms of catalytic activity, dosage, and reusability. It is a promising strategy for the green production of diosgenin.

A new family of octanuclear Cu–Ln complexes, [Cu6Ln2(tea)2{(py)2CO2}3Cl6]·xH2O (Ln = Dy (1), Tb (2), Ho (3), Er (4), Gd (5); x = 1 for 1, 3 and 5, x = 0 for 2 and x = 7 for 4; (py)2CO2H2 = the gem-diol form of di-2-pyridyl ketone, teaH3 = triethanolamine), has been synthesized and characterized by single-crystal X-ray diffraction, elemental analyses, IR and magnetic properties. These complexes are all isostructural and were obtained by following a self-assembly reaction involving CuCl2·2H2O, Ln(NO3)3·6H2O, di-2-pyridyl ketone, triethanolamine and triethylamine in acetonitrile at room temperature. Single-crystal X-ray diffraction analyses indicate that the LnIII ions in these complexes are seven-coordinate, which is rare in 3d–4f complexes and 4f complexes. The geometries of LnIII in these complexes severely deviate from capped octahedrons. Moreover, coordination sites of Ln were occupied by two (py)2CO22− and one tea3− ligands, without the presence of coordinated solvent molecules such as H2O and small anions such as NO3− ions, which is also rare in 4f ions complexes. The direct-current magnetic susceptibilities show that the ferromagnetic coupling interactions between CuII and Ln ions are presented by fitting the data of 1/χMversus T using the Curie–Weiss law and fitting the data of χMT versus T of 5 (Gd) using PHI program. AC magnetic measurements of 1–5 without dc field and 2000 Oe dc fields show no temperature- and frequency-dependent signals, which may be due to the low symmetry of the coordination configuration of Ln in these complexes.

A loop system was used to investigate the effect of flow velocity on corrosion behavior of AZ91D magnesium alloy at an elbow of loop system based on array electrode technology by polarization, computational fluid dynamics (CFD) simulation and surface analysis. The experimental results showed that the corrosion rate increased with increasing flow velocity, and a critical flow velocity could exist in the corrosion of AZ91D magnesium alloy. When flow velocity exceeded the critical flow velocity, fluid hydrodynamics was dominant in the corrosion of AZ91D magnesium alloy. On the contrary, the electrochemical factors were dominant.

Two new coordination polymers of Robson-type macrocycles, {[CuL1]n (1) and {[CuL2]n (2), were obtained by the condensation between bapa and N,N′-bis(3-formyl-5-R-salicylimine)-1,2-propylenediimine in the presence of Cu(II). These polymers have the common feature that the 3-methylaminopyridine group in one ligand coordinates to the metal ion in the neighboring coordination unit, leading to the formation of one-dimensional infinite chain. The formation of NO complexes has been confirmed by UV/Vis spectrophotometry. The binding constants were calculated to be 8.18 × 102 M− 1, 1.2 × 103 M− 1 for 1 and 2, respectively. The control experiments revealed there was non-reversible binding of NO, which can be ascribed to specially coordination environment of the central Cu(II) ions. Moreover, the interactions of the complexes with calf thymus DNA (CT-DNA) have been measured by agarose gel electrophoresis, and the results showed that they can not cleavage the CT-DNA. These two complexes can be served as potential NO scavengers. Graphical abstract Two new coordination polymers of Robson-type macrocycles, {[CuL1]n (1) and {[CuL2]n (2), were obtained by the condensation between bapa and N,N′-bis(3-formyl-5-R-salicylimine)-1,2-propylenediimine in the presence of Cu(II). The NO absorption experiments revealed a moderate binding to NO and control experiments showed the non-reversibility of the binding NO to these two macrocyclic metal Cu(II) complexes.

A one-dimensional (1D) chain [Cu3(HL)2(N3)(Mtta)]n.0.5CH3CN (1, H3L = 2-((2-hydroxybenzylidene)amino)propane-1,3-diol and Mtta = 5-methyl tetrazolate) and a Cu4Dy2 complex [Cu4Dy2{(py)2CO2}2{(py)2C(OH)O}2(CH3COO)4(N3)4].3CH3CN (2, (py)2C(OH)2 = the gem-diol form of di-2-pyridyl ketone) were obtained by the assemblies of the H3L ligand and Dy(NO3)3·5H2O with copper nitrate or with copper acetate and di-2-pyridyl ketone under the MeCN solution containing triethylamine or containing NaOH. In 1, three CuII ions were linked into a trinuclear Cu unit by three neighboring N atoms of Mtta ligand and two alkoxido-type O atoms from two HL2− ligands, then these units were further linked into a one-dimensional (1D) chain by two phenoxido O atoms from two HL2− ligands. In 2, two CuII and two DyIII ions formed a butterfly-type topology, which was further linked another two CuII by the O atoms from (py)2CO22– or from acetate ligands. Magnetic studies indicated that, in 1, the magnetic coupling through the paths of Cu N N Cu and Cu-Oalkoxido-Cu is antiferromagnetic (J1 = −14.81 cm−1), and its value was first determined in the polynuclear Cu complexes containing Mtta ligand. However, the magnetic coupling through the path of Cu-Ophenoxido-Cu is ferromagnetic (J2 = 24.61 cm−1). Magnetic studies revealed that 1 exhibits slow magnetic relaxation behavior, with an energy barrier Ueff of 6.06 K. The orientations of the easy magnetization axes of DyIII ions in 2 was estimated by Magellan program, indicating that the easy axes of DyIII in 2 are roughly aligned along alkoxido-type O atoms (O3 and O3a), which is slightly longer than other Dy-O distances.

In the present work, a 3D metal–organic frameworks (MOFs) of {[Mn2(BPDC)2]⋅DMF}n was successfully synthesized via solvothermal method based on 2,2′-biisonicotinic acid (H2BPDC) as ligand. The synthesized complex was characterized by single-crystal X-ray diffraction, thermogravimetric analyzer (TGA), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), X-ray Photoelectron Spectroscopy (XPS) and UV–vis diffuse reflectance spectroscopy(DRS). 4-Nitrophenol (4-NP) and Methyl Orange (MO) contaminants were selected as model contaminants to investigate the photocatalytic properties of the complex. In order to further evaluate the photocatalytic activity, the effects of the pH value and the catalyst dosage have been investigated. Under the optimized conditions, 97.72% of the photocatalytic degradation efficiency for MO was obtained. Moreover, only in 5 mins, the reduction efficiency for 4-NP reached 99.92% under the UV light irradiation. Accordingly, the results indicated that the superoxide radicals were main active substance in the process of photocatalytic degradation. It is worth mentioning that the complex could be recycled five times without noticeable loss of activity.

An unprecedented Tb(iii) polycarboxylate, {[Tb4(TTHA)2(H2O)4]·7H2O}n (1), has been synthesized. It possesses an efficient proton transfer pathway formed by water molecules and carboxyl groups, which exhibits proton conductivity over 10-2 S cm-1 at 295-358 K and 98% relative humidity.