Search

Two proton-conductive and luminescent organic-inorganic hybrid materials, {[Cu(II)(bhmbpy)(H2O)(Cl)0.5(CH3CN)]2[PW(VI)10W(V)2O39]}·4H2O(1) and {H2[Cu(I)(bhmbpy)2(Cl)Cu(I)(bhmbpy)2][PW12O40]}·7H2O (2) (where bhmbpy is bis(hydroxymethyl)-2,2′-bipyridine), were synthesized at room temperature. The two products were characterized by infrared spectroscopy, X-ray single-crystal diffraction, X-ray powder diffraction, elemental and thermogravimetric analyses. The proton conductivities and luminescence of 1 and 2 were studied by using alternating-current impedance spectroscopy and luminescence spectroscopy, respectively. X-ray diffraction analysis revealed that 1 includes a decorated polyanion chain {[Cu(II)(bhmbpy)(H2O)(Cl)0.5(CH3CN)]2[PW(VI)10W(V)2O39]}n and forms a three-dimensional network structure depending on short Cl…Cl contacts and hydrogen-bonding interactions. X-ray diffraction analysis revealed that 2 includes a butterfly-like bi-nuclear copper cluster unit with a Cl-bridge, [Cu(I)(bhmbpy)2(Cl)Cu(I)(bhmbpy)2]+, and forms a three-dimensional network structure depending on hydrogen-bonding interactions. [PW12O40]3– anions fill in the network based on hydrogen-bonding and electrostatic interactions. In them, the bhmbpy acts as a bidentate nitrogen donor ligand in the chelating fashion to coordinate with the Cu(II) center in 1 and the Cu(I) center in 2. The bhmbpy in 2 successfully constrains the Cu(I) within a rigid environment in a tetragonal-pyramidal geometry. The two compounds exhibit good proton conductivity (10−4 S·cm−1) at 100 °C in the relative humidity range 35–98%. Their luminescence behaviors in the solid state at room temperature have also been investigated. Upon excitation at 384 nm, 1 exhibits three emission peaks centered at 439, 507 and 566 nm. When excited at 364 nm, 2 displays three emission peaks centered at 443, 501 and 553 nm.

The selection of the most suitable crystal structure for ions storage and the investigation of the corresponding reaction mechanism is still an ongoing challenge for the development of Mg-based batteries. In this article, high flexible graphene network supporting different crystal structures of Nb2O5 (TT-Nb2O5@rGO and T-Nb2O5@rGO) are successfully synthesized by a spray-drying-assisted approach. The three-dimensional graphene framework provides high conductivity and avoids the aggregation of Nb2O5 nanoparticles. When employed as electrode materials for energy storage applications, TT-Nb2O5 delivers a higher discharge capacity of 129.5 mAh g−1, about twice that of T-Nb2O5 for Mg-storage, whereas, T-Nb2O5 delivers a much higher capacity (162 mAh g−1) compared with TT-Nb2O5 (129 mAh g−1) for Li-storage. Detailed investigations reveal the Mg intercalation mechanism and lower Mg2+ migration barriers, faster Mg2+ diffusion kinetics of TT-Nb2O5 as cathode material for Mg-storage, and the faster Li+ diffusion kinetics, shorter diffusion distance of T-Nb2O5 as cathode material for Li-storage. Our work demonstrates that exploring the proper crystal structure of Nb2O5 for different ions storage is necessary.

Tungsten trioxide (WO3) nanostructures were synthesized by a hydrothermal method, and the influence of essential hydrothermal conditions, temperature and time, on their crystal structure, morphology and visible-light driven photocatalysis was studied. The hydrothermal temperature was varied from 120 °C to 200 °C, and the hydrothermal time changed from 12 h to 32 h. The crystal structure, morphology and photocatalytic performance of WO3 nanostructures were characterized by XRD, SEM and UV-Vis. The crystal structure of WO3 nanostructure was triclinic phase and their morphology was mainly one dimensional nanorods. Methylene blue was used as the target to evaluate their photocatalytic performance under visible light (λ>420 nm). The photocatalytic results suggest the suitable hydrothermal conditions to synthesize WO3 nanostructures for the wastewater treatment application.

Two isomorphic heterometallic 3d–4f cluster-based materials, formulated [Gd8Cr4(IN)18(μ3-O)2(μ3-OH)6(μ4-O)4(H2O)10]·13H2O (1) and [Tb8Cr4(IN)18(μ3-O)2(μ3-OH)6(μ4-O)4(H2O)10]·13H2O (2) (abbreviation: {Ln8Cr4}: Ln = Gd3+ (1); Tb3+ (2); HIN = isonicotinic acid), were achieved by hydro-/solvothermal method through using the ligand HIN. X-ray diffraction analysis illustrates eight lanthanide ions (Ln = Gd3+, Tb3+) and four transition-metal ions (Cr3+) of {Ln8Cr4} were constructed from two classical “drum-like” {Ln4Cr2} structures associated by organic ligands HIN, displaying a one-dimensional wave chain structure, which is rare. The magnetic properties of {Gd8Cr4} were inspected and showed the existence of antiferromagnetic coupling interactions between contiguous metal ions. On top of this, the magnetic entropy change of ΔSm can attain 23.40 J kg−1 K−1 (44.90 mJ cm−3 K−1) at about 3 K and ΔH = 7 T. Besides, fluorescence measurements of {Tb8Cr4} display typical characteristic Tb-based luminescence.

C38H28N2O10, triclinic, P1̄ (no. 2), a = 11.3207(6) Å, b = 11.9296(6) Å, c = 13.6079(8) Å, α = 115.195(5)°, β = 103.259(5)°, γ = 97.356(4)°, V = 1564.58(15) Å3, Z = 2, R gt(F) = 0.0537, wR ref(F 2) = 0.1286, T = 293(2) K.

C32H26N2O11Ni, monoclinic, P21/c (no. 19), a = 7.6085(5) Å, b = 23.5084(14) Å, c = 15.8052(9) Å, β = 94.207(6)°, V = 2819.4(3) Å3, Z = 4, R gt(F) = 0.0571, wR ref(F 2) = 0.1285, T = 293(2) K.

To design and develop high-performance optoelectronic functional materials, the crystal structures and compositions should be fully considered. Copper-based chalcogenides as the core materials of o...

Na(1-x)Lix(Gd0.39Y0.39Yb0.2Er0.02)F4 (0 ≤ x ≤ 1) (denoted as Na(1-x)LixReF4) solid solution microcrystals with different microstructures have been synthesized by a facile hydrothermal method. The influences of Li+ ion concentration on the morphology, crystal structure, grain size, and upconversion emission of the microcrystals are deeply investigated. It is found that the substitution concentration of Li+ not only causes the phase transition but also induces variation in morphology and size. When the substitution concentration of Li+ ions is lower (x ≤ 0.3), the obtained Na(1-x)LixReF4 microcrystals possess hexagonal structure and exhibit hexagonal prism in morphology. Whereas at the higher substitution concentration of Li+ ions (x ≥ 0.6), the crystalline phase of the final Na(1-x)LixReF4 microcrystals transformed into tetragonal structure and their morphology changed into octahedron except for the sample Na(1-x)LixReF4 with x = 0.9. Predictably, the obtained Na(1-x)LixReF4 microcrystals at the moderate s...

Three new zinc(II) complexes, namely, [Zn2(H2L1)2(OAc)2] (1), [Zn3(H2L1)2(OAc)4] (2) and {[Zn3(H2L2)2(OAc)4]·C2H5OH·DMF} (3) [(H3L1 = Schiff-base derived from salicylaldehyde and 2-amino-2-ethyl-1,3-propanediol and H3L2 = Schiff-base derived from 5-chlorosalicylaldehyde and 2-amino-2-ethyl-1,3-propanediol)], were synthesized and characterized using elemental analyses, infrared spectroscopy and X-ray diffraction. Single crystal structure analysis reveals that complex 1 is five-coordinated distorted square pyramidal configuration. Complexes 2 and 3 exhibit the similar trinuclear structure. And the alkoxy groups in the ligands are play an important role in the formation of supramolecular networks of complexes 1–3. The interaction of the complexes 1–3 with calf thymus (CT) DNA was investigated using UV–visible (UV–Vis), circular dichroism spectra (CD), fluorescence, viscosity and thermal denaturation methods. The intrinsic binding constants for the complexes are found to order of 104 indicating that the complexes are good metallo-intercalators. Complex 1 shows maximum binding affinity (Kb: 7.64 × 104) compared to others. The all complexes can bind to CT-DNA via intercalative mode. The MTT assay show that the cytotoxicity of dinuclear complex 1 is more effective with HeLa cancerous cells. All the experimental results are suggestive that the nuclearity and configuration of zinc complexes have significant influence on their properties.

Ho3+/Gd3+ co-doped YbNbO4 phosphors were successfully synthesized by the high-temperature solid-state method. The crystal structure, morphology structure, element distribution, up-conversion luminescence and relative optical temperature sensing properties were investigated. X-ray diffraction (XRD) and field emission-scanning electron microscopy (FE-SEM) analysis demonstrated that the doping of Ho3+/Gd3+ ions had no change in crystal structure and microstructure of YbNbO 4 phosphors. Under the excitation of 980 nm laser radiation, the green and red UC emissions were achieved by prepared phosphors, corresponding to the transitions of (5F4, 5S2)→5I8, 5F5→5I8 of Ho3+ ions. It is observed that the UC luminescence intensity was significantly enhanced for Ho3+/Gd3+ co-doped YbNbO4 samples compared to the mere Ho3+ doped YbNbO4 sample. Moreover, Ho3+/Gd3+ co-doped YbNbO4 samples' temperature sensitivity ranging from 303 to 663 K was calculated based on the fluorescence intensity ratio (FIR) method. The maximum sensitivity reached 0.0078 K−1 at 663 K. These results indicate that the YbNbO4:Ho3+/Gd3+ samples are a promising candidate for optical temperature sensing and up-conversion luminescence.

Two novel Cd-based coordination polymers Cd(H2BCP)2(phen)2 1 and {[Cd6(BCP)4(phen)3]·2H2O}n 2 (Phen=1,10-phenanthroline) have been hydrothermally synthesized from a combination of 4-(phosphonomethyl) benzoic acid 4-HOOCC6H4CH2PO3H2 (H3BCP) and 1,10-phenanthroline. The X-ray crystal structure analyses revealed that 1 is a 0D mononuclear molecular structure and 2 is a 3D structure existing the novel Cd6 cluster unit. It is worth mentioning that 1 and 2 have the same constitutional units, namely the Cd ion, H3BCP ligand and second ligand- Phen. However, their structures are different and it results from the different solution pH value. In order to explore the structural characteristics, FTIR, photo-luminescent and solid UV-Vis spectra are employed. Synthesis and properties of two novel Cd-based coordination polymers Cd(H2BCP)2(phen)2 1 and {[Cd6(BCP)4(phen)3]·2H2O}n 2 are reported. It is worth mentioning that 1 is zero-dimensional structure and forms super-molecular layers via O–H···O under the condition of solution pH = 2.1, 2 is a three-dimensional framework and contains the novel Cd6 cluster unit under the condition of solution pH = 5. So controlling the pH of the solution plays an important role in the structure of the compound.

Cyanophages, widespread in aquatic systems, are a class of viruses that specifically infect cyanobacteria. Though they play important roles in modulating the homeostasis of cyanobacterial populations, little is known about the freshwater cyanophages, especially those hypothetical proteins of unknown function. Mic1 is a freshwater siphocyanophage isolated from the Lake Chaohu. It encodes three hypothetical proteins Gp65, Gp66, and Gp72, which share an identity of 61.6% to 83%. However, we find these three homologous proteins differ from each other in oligomeric state. Moreover, we solve the crystal structure of Gp72 at 2.3 A, which represents a novel fold in the α + β class. Structural analyses combined with redox assays enable us to propose a model of disulfide bond mediated oligomerization for Gp72. Altogether, these findings provide structural and biochemical basis for further investigations on the freshwater cyanophage Mic1.

The title complex Cd/4-(phosphonomethyl) benzoic acid 4-HOOCC6H14CH2PO3(H3BCP) with 1,10-phenanthroline has been hydrothermally synthesized directly as [Cd3(BCP)2(phen)]·H2O 1 (phen = 1,10-phenanthroline). The crystal structure was determined by single-crystal X-ray diffraction with the following data: triclinic P-1. The complex is a two-dimensional layer structure. Interestingly, the one-dimensional cluster chain is composed of the novel repeated La4 cluster units connected by two Cd3 ions. The adjacent cluster chains link to be 2D layer structure by the coordination interaction of oxygen atoms of the carboxyl with the Cd3 ions of the adjacent chains. It is worthy of mentioning that IR, photo-luminescent and solid UV–Vis spectrum are employed in order to explore the structural characteristics.

Bi4O5Br2 nanosheets have been fast synthesized via a facile aqueous method. The morphology, crystal structure, optical property, and electronic structure of the obtained samples were discussed. During the reaction process, it was found that the reaction parameters including the amount of NaBr and the amount of NaOH significantly influenced the composition and structure of the samples. The photocatalytic performance of the prepared samples was explored by degrading BPA under visible-light irradiation. Bi4O5Br2 nanosheets exhibited enhanced photocatalytic activity in comparison to BiOBr or Bi5O7Br, which can be attributed to its higher visible-light absorption and lower interface charge transport resistance. Additionally, the photocatalytic degradation mechanism over Bi4O5Br2 nanosheets was also investigated. h+ and •O2− were the main photoactive species during the visible-light photocatalytic process by quencher experiments and EPR results. This study is expected to provide new insights into the development on facile fabrication and potential application of Bi-deficient bismuth oxybromide photocatalysts.

Bismuth chalcogenides, including: Bi 2 O 3 , Bi 2 S 3 , Bi 2 Se 3 , and Bi 2 Te 3 , are important photoelectric functional materials, and have a wide range of applications. In this article, first-principles calculations were performed to investigate the crystal structure, electronic properties, and optical properties of these compounds. The relationship between crystal micro-structure, electronic structure, and optical properties has been systematically investigated. On one hand, from Bi 2 O 3 to Bi 2 Te 3 , with the increasing atomic number of the Group VI elements, the electronic structures and optical properties exhibit obvious similarities and tendencies. The bonding varies within the series from strongly ionic in the oxide of Bi 2 O 3 , to iono-covalent in the sulfide of Bi 2 S 3 and selenide of Bi 2 Se 3 , to weak covalent and Van der Waals in the teliuride of Bi 2 Te 3 . Owing to the difference between chain-like structure and layered structure, the gain of electrons of Se atoms in Bi 2 Se 3 with orthorhombic structure is more than that of in Bi 2 Se 3 with trigonal structure. Based on the calculated results, it is found that the optical properties are determined by the components of the bismuth chalcogenide compounds as well as the micro-structure of the bismuth chalcogenide compounds. These calculated results can provide reliable data and support for the development of new bismuth-based optoelectronic materials and devices.

For photocatalytic applications, the response of a material to the solar spectrum and its redox capabilities are two important factors determined by the band gap and band edge position of the electronic structure of the material. The crystal structure and composition of the photocatalyst are fundamental for determining the above factors. In this article, we examine the functional material Ta–O–N as an example of how to discuss relationships among these factors in detail with the use of theoretical calculations. To explore how the crystal structure and composition influence the photocatalytic performance, two groups of Ta–O–N materials were considered: the first group included e-Ta2O5, TaON, and Ta3N5; the second group included β-Ta2O5, δ-Ta2O5, e-Ta2O5, and amorphous-Ta2O5. Calculation results indicated that the band gap and band edge position are determined by interactions between the atomic core and valence electrons, the overlap of valence electronic states, and the localization of valence states. Ta3N5 and TaON are suitable candidates for efficient photocatalysts owing to their photocatalytic water-splitting ability and good utilization efficiency of solar energy. δ-Ta2O5 has a strong oxidation potential and a band gap suitable for absorbing visible light. Thus, it can be applied to photocatalytic degradation of most pollutants. Although a-Ta2O5, e-Ta2O5, and β-Ta2O5 cannot be directly used as photocatalysts, they can still be applied to modify conventional Ta–O–N photocatalysts, owing to their similar composition and structure. These calculation results will be helpful as reference data for analyzing the photocatalytic performance of more complicated Ta–O–N functional materials. On the basis of these findings, one could design novel Ta–O–N functional materials for specific photocatalytic applications by tuning the composition and crystal structure.

Two new dinuclear Cd(II) complexes, [CdL1Cl2]2·H2O (1) and [CdL1(N3)2]2·CH3OH (2) and one dicyanamide bridged one-dimensional polynuclear network [CdL1(μ1,5-dca)dca]n (3) of the potentially tridentate NNN-donor Schiff base 2-((1H-benzimidazol-2-yl-ethylimino)-methyl)pyridine (L1) and another dinucler Cd(II) complex [CdL2Cl(dca)]2 (4) of a similar NNN-donor Schiff base ligand 2-((1H-benzimidazol-2-yl-propylimino)-methyl)pyridine (L2), have been synthesized and characterized by elemental analyses, IR and single crystal X-ray crystallography. The ligands L1 and L2 are [1 + 1] condensation products of pyridine-2-carbaldehyde with 2-aminoethyl-1H-benzimidazole and 2-aminopropyl-1H-benzimidazole, respectively. In the complexes 1 and 4 the two Cd(II) centers are held together by the bridged chloride ligands, while in 2 the two Cd(II) centers are bridged by μ1,1-azide ions. Complex 3 has a one-dimensional infinite chain structure in which Cd(II) ions are bridged by single dicyanamide groups in end-to-end fashion. All the metal centers have a distorted octahedral geometry and H-bonding or π⋯π interactions are operative to bind the complex units in the solid state. Furthermore, these complexes have been investigated by thermogravimetric analyses and fluorescence spectra.

A relaxor-based ferroelectric single crystal with the nominal composition of xPb(Sm0.5Nb0.5)O3-(0.7‒x) Pb(Mg1/3Nb1/3)O3-0.3PbTiO3 (x = 0.01, 0.02, and 0.03) was grown by the vertical Bridgman process. The electrical properties and the ferroelectric domains, as well as the luminescent characteristics of the single crystals, were investigated systematically. The piezoelectric coefficient d33 of the single crystals are slightly higher than that of the undoped PMN-PT single crystal under direct current polarization, while the crystal wafers gain a much higher d33 value upon being polarized with alternating current voltage. The single crystals possess a decreased phase transition temperature of around 60 °C and a decreased Curie temperature of 92~116 °C compared with the undoped PMN-PT single crystal. The crystal wafers polarized with alternating current voltage exhibited a desirable optical transmittance, which is associated with the domain structure changes inside the crystal medium. The domain density of the crystal wafers under alternating current polarization was significantly decreased compared with the direct current polarized crystal wafers. The luminescent spectra of the crystal wafers exhibit the typical emission peaks corresponding to the characteristic transition of Sm3+ ions in the crystal lattice.

The use of molecular iodine to tune the electrical conductivity in metal-organic frameworks is an effective but seldom investigated strategy. Herein, the single-crystal-to-single-crystal transformation of [Co1.5 (bdc)1.5 (H2 bpz)]⋅DMF⋅4 H2 O (1) to [Co1.5 (bdc)1.5 (H2 bpz)]⋅0.5 I2 ⋅DMF (I2 @1) (H2 bdc=1,4-benzenedicarboxylic acid, H2 bpz=3,3',5,5'-tetramethyl-4,4'-bipyrazole) upon I2 loading caused a three orders of magnitude enhancement in electrical conductivity of the framework. Single-crystal X-ray diffraction revealed that I2 exists as a single molecule embedded in the channels of framework, and the C-H⋅⋅⋅I hydrogen bonds between I2 molecules and phenyl units on the porous surface of the framework were suggested to participate in n→σ* host-guest charge transfer, leading to increased electrical conductivity in I2 @1. Furthermore, 1 displayed moderate adsorption selectivity for CO2 over CH4 and N2 .

C40H28Cl4N4O4Zn, monoclinic, C2/c (no. 19), a = 26.573(4) Å, b = 12.898(2) Å, c = 11.4503(17) Å, β = 110.837(12)°, V = 3667.8(10) Å3, Z = 4, R gt(F) = 0.0631, wR ref(F 2) = 0.1100, T = 293(2) K.

Using first-principles calculations, the crystal structure, mechanical property and electronic structure were investigated systematically for TM-Si (TM = V, Nb and Ta) systems. Pm 3 ¯ n-V3Si, I4/mcm-V5Si3 and P6222-VSi2 for V-Si system, I4/mcm-Nb5Si3, P6222-NbSi2 for Nb-Si system, and P42/n-Ta3Si, I4/mcm-Ta2Si, I4/mcm-Ta5Si3, P6222-TaSi2 for Ta-Si system, are identified as thermodynamically stable structures, well consistent with previous theoretical and experimental reports. Stable P4/mbm-Nb3Si2, P41212-Nb5Si4, Ibam-Nb6Si5, Pnma-NbSi and P4/mbm-Ta3Si2 are proposed to be more likely realized in experiment because their formation enthalpies are close to convex-hull. The general order of bulk modulus is found to be Ta-Si > Nb-Si > V-Si at each stoichiometry. P6222-TMSi2 in each system shows the better mechanical properties. Both covalent bonding between Si-Si and Si-TM in TMSi2 are responsible for the structural stability and good mechanical property. The present study may shed light on better understanding of the phase relations in these transition metal silicides.

Carboxysome, encapsulating an enzymatic core within an icosahedral-shaped semipermeable protein shell, could enhance CO2 fixation under low CO2 conditions in the environment. The shell of Halothiobacillus neapolitanus α-carboxysome possesses two 38% sequence-identical pentameric proteins, namely CsoS4A and CsoS4B. However, the functions of two paralogous pentameric proteins in α-carboxysome assembly remain unknown. Here we report the crystal structure of CsoS4B at 2.15 A resolution. It displays as a stable pentamer, each subunit of which consists of a β-barrel core domain, in addition to an insertion of helix α1 that forms the central pore. Structural comparisons and multiple-sequence alignment strongly indicate that CsoS4A and CsoS4B differ from each other in interacting with various components of α-carboxysome, despite they share a similar overall structure. These findings provide the structural basis for further investigations on the self-assembly process of carboxysome.

A new Co(II) polymer [Co(btc)(4,4′-bipyridine)]n 1 (H4btc = 3,3′,4,5′-biphenyl tetracarboxylic acid) was synthesized under hydrothermal conditions. The compound crystallizes in the triclinic system, space group P-1 with a = 6.4834(15), b = 13.495(3), c = 14.933(3) A, α = 104.044(3), β = 98.844(3), γ = 94.987(3)°, V = 1241.9(5) A3, Z = 2, Mr = 690.33, Dc = 1.846 Mg/m3, μ = 1.417 mm−1, F(000) = 704, the final R = 0.0491, and wR = 0.0925 for 4581 observed reflections with I > 2σ(I). The compound presents a three-dimensional (3D) network extended by both btc4− anions and 4,4′-bipyridine ligands in which the btc4− anions employ a chelating coordination mode. From the topology point of view, the structure could be described as a (3 4,5)-connected 3D network with (4.62)(42.66)(43.64.83) topology net. Infrared spectroscopy, elemental analyses, thermogravimetric analysis, and powder X-ray diffraction properties of 1 are also investigated.

The reaction between the 1,1′-carbonyldiimidazole and Co(NO3)2·6H2O produced the crystalline material [Co(Im)6](NO3)2 (Im=imidazole). The crystal structure of [Co(Im)6](NO3)2 has been determined via X-ray diffraction and the result showed that Co(II) ion is coordinated by six nitrogen atoms from six ligands in a slightly distorted octahedral arrangement. The N-H…O hydrogen bonds generate a structure with two-dimensional networks. [Co(Im)6](NO3)2 was characterized via elemental analysis, FT-IR, and UV-Vis spectroscopy and the thermal stability of the complex has also been investigated in the solid state. In addition, the antibacterial activity of Im and [Co(Im)6](NO3)2 to Staphylococcus aureus was studied.

This study elucidated the effects of crystalline structure and acidity of sulfation-acidified HZSM-5 (HZ5) catalyst on the reaction routes and light aromatics (LAs) distribution during catalytic fast pyrolysis (CFP) of Shengli lignite. HZ5 modified by (NH4)2SO4 (AS), (NH4)2S2O8 (APS), and H2SO4 (HS) were applied to conduct CFP of lignite in a drop tube quartz reactor at 600 °C. The results indicated that the yield of LAs, especially monocyclic aromatics, increased considerably as the increase of pore size and midstrength acid sites (the decrease of non-shape selective acid sites) caused by sulfation-acidification modification. Among all the modified catalysts, 0.5AS-550 (modified with 0.5 mol/L AS and calcined at 550 °C) showed a better prospect than APS and HS modification in promoting the formation of LAs (the maximum yield of 28.8 mg/g). Meanwhile, the elimination of non-shape selective acid sites and regeneration of mesoporous reduced coke yield by 0.6% compared to HZ5. In addition, the possible reaction routes and catalytic mechanism over sulfation-acidified HZ5 catalysts were proposed to describe the formation of LAs.

Long-term instability and possible lead contamination are the two main issues limiting the widespread application of organic-inorganic lead halide perovskites. Here a facile and efficient solution-phase method is demonstrated to synthesize lead-free Cs2 SnX6 (X = Br, I) with a well-defined crystal structure, long-term stability, and high yield. Based on the systematic experimental data and first-principle simulation results, Cs2 SnX6 displays excellent stability against moisture, light, and high temperature, which can be ascribed to the unique vacancy-ordered defect-variant structure, stable chemical compositions with Sn4+ , as well as the lower formation enthalpy for Cs2 SnX6 . Additionally, photodetectors based on Cs2 SnI6 are also fabricated, which show excellent performance and stability. This study provides very useful insights into the development of lead-free double perovskites with high stability.

Impurity doping is a simple and efficient modification method to improve the photocatalytic performance of wide band gap photocatalysts. However, some basic and important issues about the mechanism of impurity doping modification still need to be further confirmed and explained. In the present work, Pr-doped TiO2 with a mono-phase crystal structure was prepared by a sol-gel method. Then, the crystal structure, binding information, optical absorption, and photocatalytic activity were systematically investigated. The experimental results show that Pr doping could significantly enhance the photocatalytic activity of TiO2, and the effects of modification on rutile TiO2 are more obvious than for anatase TiO2. In order to understand the underlying mechanism, density functional theory was utilized to calculate the crystal structure and electronic structure of pure and Pr-doped TiO2. The differences in electronic structure between anatase and rutile phases lead to the above photocatalytic performance. The experimental measurements and theoretical calculations mutually support each other in the present work. Two points are confirmed: the position of the band edge determines the redox activity of the photocatalyst, and the shallow energy bands induced by impurity doping could improve the photocatalytic performance.

As promising solar cell absorb materials, detailed density functional theory calculations of the structural, electronic, and optical properties of Cu 2 ZnSn(S 1 − x Se x ) 4 alloys with different crystal structures (including: zincblende-derived kesterite, zincblende-derived stannite, wurtzite-derived kesterite, and wurtzite-derived stannite) over the whole range of Se composition from x = 0 to x = 1 were systematically investigated in the present work. The calculated results revealed that the lattice constants variation of Cu 2 ZnSn(S 1 − x Se x ) 4 alloys obey the Vegard’s law; and the wurtzite-derived alloys have better alloy solubility and component-uniform compared with zincblende-derived alloys. In the whole range of x, the calculated lattice constants, band gaps, dielectric constants, and refractive index are nearly linear varying with Se compositions. Using the fitting functional relationships, one not only designs suitable Cu 2 ZnSn(S 1 − x Se x ) 4 alloys as absorber materials for solar cells, but also determines the composition of Cu 2 ZnSn(S 1 − x Se x ) 4 alloys by conventional optical measurements in practice.

Europium-doped luminescent heavy metal bismuth oxychloride has been investigated by first-principles calculation, and the crystal structure, electronic structure, and optical properties of pure BiOCl and Eu-doped BiOCl have been examined and compared. Based on the calculated results, the luminescence properties and mechanism of Eu-doped BiOCl has been discussed. Owing to the unique layered structure, BiOCl host could produce enough separated electron–hole pairs, under UV-light excitation. Furthermore, because the energy levels (5D0) of Eu3+ is matched with the energy bands (the bottom of conduction band) of BiOCl, the energy transport and charge transfer from host to luminescence center can be efficiently carried out. Thus, the photoluminescence of Eu3+ could be enhanced in the matrix of BiOCl. These findings are helpful to understand previously published experimental results, and to improve novel luminescence materials.

A new three-dimensional (3D) coordination polymer has been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, and X-ray diffraction. The X-ray diffraction analysis reveals that the polymer crystallizes in monoclinic system, space group C2/c. Unit cell parameters: a = 25.444(2), b = 5.8508(5), c = 19.0633(17) A, α = 90°, β = 124.1250(10)°, γ = 90°, V = 2349.2(4) A3, Z = 4. The polymer can be specified by the Schlafli symbol (42·64)(42·67·8) as a 3D (4,5)-connected net.

Metastable tetragonal bismuth oxide (β-Bi 2 O 3 ) architectures of pumpkin shape were successfully prepared by a solution crystallization technique, which was performed at 70 °C without further calcination or other complex treatment. The elementary units of β-Bi 2 O 3 architectures are microrods of ~1 μm in width. The metastable crystalline structure was determined by X-ray powder diffraction (XRD), and the crystal evolution process from irregular particles to pumpkin aggregates was investigated on a field emission scanning electron microscope (FESEM). The tetragonal β-Bi 2 O 3 crystalline powders exhibited orange in color, which could transform to yellow monocline α-Bi 2 O 3 crystals upon enough reaction time as 60 min, the corresponding morphology changes from pumpkin structure of β-Bi 2 O 3 crystals to big diamond structure of α-Bi 2 O 3 crystals. The stabilization of metastable β-Bi 2 O 3 crystals in the solution system is a size controlled process. By tuning experimental parameters, such as NaOH concentration, reaction temperature, stirring rate etc., metastable β-Bi 2 O 3 crystals can preserve stably in the reaction system for different time. The pumpkin β-Bi 2 O 3 architectures showed excellent photocatalytic activity to Rhodamine B (RhB) degradation under visible light irradiation, which is due to an indirect dye photosensitization degradation process.

The title compound, 2-(γ-aminopropyl)benzimidazole dichloride dihydrate ([H2APB2+][Cl−]2·2H2O), was synthesized and characterized by elemental analysis, IR, UV, 1H NMR, and fluorescent spectroscopic method. Single-crystal X-ray analysis was performed, which reveals that the benzimidazole and amine nitrogen atoms are protonated. The [H2APB2+] ions are linked into a 3D framework by chloride ions and two water molecules via hydrogen bonds, C‒H···π and π-π packing interactions between adjacent benzimidazole rings. Antibacterial activities of [H2APB2+][Cl−]2·2H2O have been studied on the strains S. aureus and E. coli.

C28H20N2Cl4O4Cd, monoclinic, P21/c (no. 14), a = 12.5272(4) Å, b = 28.7754(10) Å, c = 7.7485(3) Å, β = 96.627(1)°, V = 2774.48(17) Å3, Z = 4, R gt(F) = 0.0341, wR ref(F 2) = 0.0787, T = 296(2) K.

C40H28N4O10Cd, monoclinic, P21/c (no. 14), a = 9.5953(8) Å, b = 22.1448(17) Å, c = 16.3937(13) Å, β = 90.528(1)°, V = 3483.3(5) Å3, Z = 4, R gt (F) = 0.068, wR ref (F 2 ) = 0.1343, T = 296(2) K.

C12H18O14S2Mn, Triclinic, P1̅, a = 6.5076(10) Å, b = 8.4923(13) Å, c = 9.8092(15) Å, α = 66.6180(10)°, β = 86.903(2)°, γ = 82.235(2)°, V = 493.02(13) Å3, Z = 1, R gt (F) = 0.0569, wR ref (F 2 ) = 0.1756, T = 296(2) K.

C24H16N3O11Co2, monoclinic, P21/n, a = 7.3343(2) Å, b = 42.2275(12) Å, c = 7.5118(2) Å, β = 100.988(3)°, V = 2283.82(11) Å3, Z = 4, R gt (F) = 0.0365, wR ref (F 2 ) = 0.1142, T = 293(2) K.

C40H40N4O12Ni, triclinic, P1̅, a = 7.6612(6) Å, b = 8.0725(7) Å, c = 16.3021(10) Å, α = 89.394(6)°, β = 77.966(6)°, γ = 69.868(8)°, V = 923.75(12) Å3, Z = 1, R gt (F) = 0.0492, wR ref (F 2 ) = 0.1309, T = 293(2) K.

C28H22O6N8Cu, Triclinic, P1̅, a = 6.826(5) Å, b = 9.040(7) Å, c = 10.930(8) Å, α = 101.068(8)°, β = 95.054(8)°, γ = 96.278(8)°, V = 653.8(9) Å3, Z = 1, R gt (F) = 0.0469, wR ref (F 2 ) = 0.1063, T = 293(2) K.

C26H18N2O8, triclinic, P1̅ (No. 2), a = 10.101(5) Å, b = 10.589(6) Å, c = 10.705(6) Å, α = 93.183(8)°, β = 108.614(8)°, γ = 97.323(8)°, V = 1070.5(10) Å3, Z = 2, R gt (F) = 0.0399, wR ref (F 2 ) = 0.1027, T = 296(2) K.

Iron oxide particles with spherical, date-pit like, or polyhedron morphology were obtained by hydrothermal method. The morphology, thermal analysis, crystal structure of the products was characterized by FESEM, thermogravimetry (TG), X-ray diffraction (XRD), respectively. The measured results reveal that the product of three different shapes is hematite (α-Fe2O3).

By the introduction of oxalate as the second ligand, five new lanthanide oxalatophosphonate hybrids with a 2D layered structure, namely, [Ln(H2L)(C2O4)(H2O)]·2H2O [Ln = Nd (1), Sm (2), Eu (3), Tb (4), Dy (5), H3L = H2O3PCH2NCH2(CH2CH2OPO2H)], have been hydrothermally synthesized and structurally characterized by X-ray single-crystal diffraction, X-ray powder diffraction, infrared spectroscopy, elemental analysis and thermogravimetric analysis. Compounds 1-5 are isostructural and exhibit a 2D layer formed by the interconnection of a 1D zigzag chain of {Ln(C2O4)}(+) with the phosphonate ligands. The effect of lanthanide contraction induces the decrease of the lattice parameters and crystal size from Nd to Dy. The luminescence properties of compounds 2-5 have been studied.

Three new coordination polymers, namely, [ML(H2O)]n (M = Co (1), Zn (2)) and [CuL(DMF)]n (3), have been hydrothermally synthesized through the reaction of bifunctional ligand 5-((2-methyl-1H-imidazol-1-yl)methyl)benzene-1,3-dioic acid (H2L) with divalent cobalt, zinc and copper salts, and structurally characterized by elemental analysis, IR and X-ray diffraction. Both complexes 1 and 2 are two-fold interpenetration 3D frameworks. Complex 3 exhibits (3,6)-connected framework with (4.62)2(42.610.83) topology. Furthermore, UV–vis absorption spectra and powder X-ray diffraction (PXRD) were investigated as well.

In order to explore the relationship between crystal structure and optical properties, five Si–O–N compounds with different crystal structures, including: α-quartz SiO2, β-quartz SiO2, Si2N2O, α-Si3N4, β-Si3N4 were considered in the present work. Using density functional theory with the GGA+U method, their crystal structure, electronic structure, and optical properties have been systematically investigated. The electronic structure of α and β phases of SiO2 (or Si3N4) are similar, but with some subtle differences that can be attributed to the different local bonding structure, and the electronic structure of Si2N2O shows the fundamental features of the electronic properties of SiO2 and Si3N4. Based on the calculated results, it is found that the optical properties not only are determined by the components of the Si–O–N compounds, but also are determined by the microstructure of the Si–O–N compounds. These calculated results will be useful as reference data for analyzing the optical properties of more complicated SiOxNy compounds. According to this principle, one could design novel Si–O–N compounds for specific optoelectronic applications, via tuning the composition and crystal structure.