An Orthorhombic Polymorph of Lanthanum Ultraphosphate LaP_5O_（14）：Synthesis, Structure and Density Functional Study

An orthorhombic polymorph of lanthanum ultraphosphate, LaP5O14, was firstly synthesized by the high temperature solid-state reaction and structurally characterized by single-crystal X-ray diffraction technique. It crystallizes in the orthorhombic Pmna space group with a=13.155(3), b=8.816(2), c=9.115(2) , V=1057.1(4) 3 and Z=4. The structure features (P5O14)3-anionic ribbons linked with neighboring LaO8 polyhedra. The title solid-state compound is an insulator. Theoretically calculated energy band structure, density of states (DOS), and optical response function by density function theory (DFT) for LaP5O14 were also performed.     

Synthesis and Crystal Structure of a Polyoxomolybdate Framework Modified by Mn-L Units（L=3-（2-Pyridyl）pyrazole）

A new polyoxomolybdate compound,namely {[MnII(L)(4,4?-Hbipy)(H2O)2]2 [Mo5O15(PO4)2]}.2H2O 1(L = 3-(2-pyridyl)pyrazole,4,4'-Hbipy = protonated 4,4'-bipyridine),was designed and synthesized under hydrothermal conditions.Single-crystal X-ray diffraction analysis result reveals that the [Mo5O15(PO4)2]6-cluster in compound 1 links to two MnII cations via the oxygen of PO43-,which is further coordinated by one 3-(2-pyridyl)pyrazole,one 4,4'-Hbipyridine,and two water molecules.     

Two-dimensional Lanthanide Coordination Polymers Constructed from Ce3＋/pr3＋ Cation, Imidazole-4,5- dicarboxylate and in situ Generated Oxalate Anions

Two new lanthanide coordination polymers [Ln(C 5 H 2 N 2 O 4)(H 2 O) 2 (C 2 O 4) 0.5 ] n nH 2 O (Ln=Ce III (1) or Pr III (2);C 5 H 2 N 2 O 4=imidazole-4,5-dicarboxylate anion;C 2 O 4=oxalate anion) have been synthesized and structurally characterized by single-crystal X-ray diffraction,elemental analyses and IR spectrum.Both compounds crystallize in monoclinic,space group P2 1 /c with a=7.5225(3),b=17.2416(6),c=8.6089(3),β=110.9610(10)°,V=1042.68(7)3,Z=4,C 6 H 8 N 2 O 9 Ce,M r=392.26,D c=2.499 g/cm 3,μ(MoKα)=4.414 mm 1,F(000)=752,the final R=0.0167 and wR=0.0412 for 1;a=7.4973(3),b=17.2113(8),c=8.5729(4),β=110.9440(10)°,V=1033.14(8)3,Z=4,C 6 H 8 N 2 O 9 Pr,M r=393.05,D c=2.527 g/cm 3,μ(MoKα)=4.764 mm 1,F(000)=756,the final R=0.0192 and wR=0.0455 for 2.X-ray diffraction analyses reveal that the lanthanide cations in compound 1 or 2 are linked by imidazole-4,5-dicarboxylate and in situ generated oxalate anions via Ln-O and Ln-N covalent bonds to form two-dimensional layered networks.The successful synthesis of compound 1 or 2 also indicates a crystallographic confirmation for the decomposition of curcumin to form oxalate anion under solvothermal conditions.     

不同晶型Bi2O3可见光光催化降解罗丹明B的研究

采用化学沉淀法制备了α、β、γ 3种晶体结构的Bi₂O₃光催化剂。利用XRD、TEM、氮气吸附、TG-DSC、紫外-可见漫反射光谱对样品的晶体结构、微观形貌、光学吸收特性进行了表征,并以罗丹明B(RhB)作为模型污染物,研究了不同的粉体光催化剂在可见光(λ>420 nm)照射下的光催化能力。结果表明：制备的α-Bi₂O₃为长3 μm、宽1 μm的板条状颗粒,带隙为2.84 eV;β-Bi₂O₃为粒径约150 nm的不规则颗粒,带隙为2.75 eV;γ-Bi₂O₃为直径6 nm、长度150~200 nm的纳米管,带隙为2.68 eV。在可见光照射下Bi₂O₃光催化降解RhB的活性如下：γ-Bi₂O₃>β-Bi₂O₃>α-Bi₂O₃,其中γ-Bi₂O₃在辐照60 min后对罗丹明B的脱色率可达97%以上。     

Research on optical band gap of the novel GeSe2–In2Se3–KI chalcohalide glasses

The glass-forming region of the GeSe₂–In₂Se₃–KI system was reported firstly. The dependence of physical, thermal and optical properties on compositions as formula of (1 ? x)(0.8GeSe₂–0.2In₂Se₃)–xKI (x = 0, 0.1, 0.2, 0.3) chalcohalide glasses was investigated. The allowed direct transition and indirect transition, and Urbach energy of samples were calculated according to the classical Tauc equation. The results show that the glass system has good thermal stability and that there is an obvious blue-shift at the visible absorbing cutting-off edge. When the dissolved amount of KI increased from 0 to 30 mol%, the direct optical band gap and the indirect optical band gap were in the range from 1.617 to 1.893 eV and 1.573 to 1.857 eV. With the decrease of the molar refraction the refractive index decreases, optical band gap and metallization criterion increase. The relationship between energy band gap and metallization criterion was analyzed and the optical properties of chalcohalide glasses were summarized.     

The Electronic and Optical Properties of Au Doped Single-Layer Phosphorene

The electronic properties and optical properties of single and double Au-doped phosphorene have been comparatively investigated using the first-principles plane-wave pseudopotential method based on density functional theory. The decrease from direct band gap 0.78 eV to indirect band gap 0.22 and 0.11 eV are observed in the single and double Au-doped phosphorene, respectively. The red shifts of absorbing edge occur in both doped systems, which consequently enhance the absorbing of infrared light in phosphorene. Band gap engineering can, therefore, be used to directly tune the optical absorption of phosphorene system by substitutional Au doping.     

Band gap engineering of bulk ZrO2 by Ti doping

It has been experimentally observed that Ti doping of bulk ZrO(2) induces a large red-shift of the optical absorption edge of the material from 5.3 to 4.0 eV [Livraghi et al., J. Phys. Chem. C, 2010, 114, 18553-18558]. In this work, density functional calculations based on the hybrid functional B3LYP show that Ti dopants in the substitutional position to Zr in the tetragonal lattice cause the formation of an empty Ti 3d band about 0.5 eV below the bottom of the conduction band. The optical transition level ε(opt)(0/-1) from the topmost valence state to the lowest empty Ti impurity state is found at 4.9 eV in a direct band gap of 5.7 eV. The calculated shift is consistent with the experimental observation. The presence of Ti(3+) species in Ti-doped ZrO(2), probed by means of electron paramagnetic resonance (EPR), is rationalized as the result of electron transfers from intrinsic defect states, such as oxygen vacancies, to substitutional Ti(4+) centers.     

Glass formation and properties of Ge-Te-BiI3 far infrared transmitting chalcohalide glasses

A novel series of Ge-Te-BiI(3) chalcogenide glasses were prepared by traditional melt-quenching method and the glass-forming region was determined. Properties measurements including density, Vis-NIR and infrared (IR) transmission spectra with FTIR, XRD, DSC were adopted to analyze the composition, structure and performance of the Ge-Te-BiI3 glass system. Based on the metallization criterion and band gap energy theory, the relationships between energy gap, metallization criterion and glass composition was investigated. The results show that with the addition of BiI3, the glasses-forming ability and thermal stability are improved. The values of energy band gap and metallization criterion are within the range of 0.627-0.343 eV and 0.177-0.131, respectively. These series of glasses have wide optical transmission window from 2.2 to 25 μm and can offer an alternative solution for far infrared transmitting applications.     

新型同分异构芘基查尔酮的理论研究和超快三阶非线性光学响应

合成了3个新型同分异构芘基查尔酮:1-(芘-1-基)-3-(吡啶-2-基)-2-丙烯-1-酮(3a)、1-(芘-1-基)-3-(吡啶-3-基)-2-丙烯-1-酮(3b)和1-(芘-1-基)-3-(吡啶-4-基)-2-丙烯-1-酮(3c)。 通过核磁共振波谱仪(NMR)、傅里叶变换红外光谱仪(FTIR)和液-质联用仪(LC-MS)等技术手段表征3个化合物的结构、热稳定性和线性光学性质和三阶非线性光学吸收性能。 结果表明,在532 nm和180 fs条件下,化合物3a-3c均表现出超快三阶非线性光学响应,化合物3c的非线性吸收系数分别是化合物3b和3a的1.14和2.67倍。 运用密度泛函理论方法计算了化合物3a-3c的非线性光学性质及其电子性质,结果表明,化合物3c分子具有最大的静态第一超极化率(β₀)(2830.9 a.u.),并具有最小的最高占据分子轨道(HOMO)-最低空分子轨道(LUMO)之间的能隙(3.11 eV)和最小的跃迁能(ΔE)(2.67 eV),这与N原子在吡啶环上的位置有关;分子内部均存在电荷转移现象。 3个化合物的紫外-可见光谱在450 nm以上无吸收,有良好的热稳定性,在激光防护方面有应用前景。     

Tuning of optical band gaps: syntheses, structures, magnetic properties, and optical properties of CsLnZnSe(3) (Ln = Sm, Tb, Dy, Ho, Er, Tm, Yb, and Y)

Eight new quaternary selenides CsSmZnSe(3), CsTbZnSe(3), CsDyZnSe(3), CsHoZnSe(3,) CsErZnSe(3), CsTmZnSe(3), CsYbZnSe(3), and CsYZnSe(3) have been synthesized with the use of high-temperature solid-state experimental methods. These compounds are isostructural with KZrCuS(3), crystallizing with four formula units in the orthorhombic space group Cmcm. The structure of these CsLnZnSe(3) compounds is composed of [LnZnSe(3)(-)] layers separated by Cs atoms. The Ln atom is octahedrally coordinated by six Se atoms, the Zn atom is tetrahedrally coordinated by four Se atoms, and the Cs atom is coordinated by a bicapped trigonal prism of eight Se atoms. Because there are no Se-Se bonds in the structure, the oxidation state of Cs is 1+, that of Ln is 3+, and that of Zn is 2+. CsYbZnSe(3) exhibits an antiferromagnetic transition at 11 K, whereas CsSmZnSe(3) does not follow a Curie-Weiss law. The remaining rare-earth compounds are paramagnetic, and the calculated effective magnetic moments of the rare-earth ions agree well with their theoretical values. Optical absorption data on face-indexed single crystals of CsSmZnSe(3), CsErZnSe(3), CsYbZnSe(3), and CsYZnSe(3) demonstrate that the optical band gap changes by more than 0.75 eV with the composition and by as much as 0.20 eV with the crystal orientation. The optical band gaps range from 2.63 eV (CsSmZnSe(3), CsErZnSe(3)) to 1.93 eV (CsYbZnSe(3)) for the (010) crystal face and 2.56 eV (CsErZnSe(3)) to 1.88 eV (CsYbZnSe(3)) for the (001) crystal face. The difference in the optical band gap of the (010) face vs the (001) face varies from +0.05 eV (CsYbZnSe(3)) to +0.20 eV (CsSmZnSe(3)).     

Syntheses and Crystal Structures of Two Octamolybdate Compounds Modified by CuⅡ-Imidazole Cations

Two new polyoxomolybdate compounds,namely(CuIIL2)2[CuⅡ(HL)2]2[Mo8O26(HL)2].(H2O)4(1) and [CuⅡ(HL)2]2[β-Mo8O26](HL)2(2)(HL=imidazole),were designed and synthesized under hydrothermal conditions.X-ray diffraction analyses reveal that compound 1 consists of one Mo8O26(HL)24-cluster,two CuL2,two Cu(HL)22+,and four disassociated water molecules;and compound 2 is constructed by one β-Mo8O264-cluster,two Cu(HL)22+,and two uncoordinated imidazole molecules.     

A Lanthanide-transition Metal Coordination Polymer：{[CuEu（Hbidc）_2（H_2O）_4]·H_2O}_n（H_3bidc=1H-benzimidazole-5,6-dicarboxylic Acid）

The title complex 1,{[CuEu(Hbidc)2(H2O)4]·H2O}n(H3bidc = 1H-benzimidazole-5,6-dicarboxylic acid),has been solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction.Complex 1 crystallizes in triclinic,space group P1,with a = 7.791(2),b = 12.058(3),c = 12.109(3),α = 82.189(5),β = 72.407(5),γ = 89.184(4)°,V = 1073.7(5)3,C18H18CuEuN4O13,Mr = 713.86,Dc = 2.208 g/cm3,μ(MoKα) = 3.967 mm-1,F(000) = 700,GOOF = 0.950,Z = 2,the final R = 0.0531 and wR = 0.1068 for I > 2σ(I).Complex 1 possess a tape-like chain structure consisting of Eu2C8O4 and Cu2Eu2C18N4O4 metallic rings alternatively arranged and is the first 3d-4f heterometallic complex based on the 1H-ben-zimidazole-5,6-dicarboxylato ligand(Hbidc).Plenty of hydrogen-bonding and π...π stacking interactions connect the 1D chains to construct a 3D supramolecular architecture.     

纳米尺度TiO2聚苯胺多孔膜电极光电化学研究

用光电流作用谱，光电流－电势图等光电化学方法研究了ＴｉＯ２／聚本胺复合多孔膜电极在不含氧化还原和含有没氧化还原对体系中的光电转换过程。结果说明，ＴｉＯ２／聚苯胺复合多孔膜电极为双层ｍ－型半导体结构，ＴｉＯ２多孔膜的禁带宽度为３．２ｅＶ，外层聚苯胺膜的禁带宽度为２．８８ｅＶ。     

Synthesis, Crystal Structure and Antibacterial Activity of a New Ternary Copper（Ⅱ） Complex with 2,6-Pyridinedicarboxylic Acid and 1,10-Phenanthroline

A new ternary copper(II) complex,[C 43 H 27 Cu 2 N 7 O 5 ]·[C 14 H 6 CuN 2 O 8 ]·6.5H 2 O,has been synthesized by the reaction of copper sulfate,2,6-pyridinedicarboxylic acid and 1,10-phenanthroline (phen),and characterized by elemental analysis,IR,UV and X-ray single-crystal diffraction.It crystallizes in triclinic,space group P1,with a=14.379(5),b=15.510(5),c=15.835(6),α=78.567(6),β=63.594(6),γ=81.287(6)°,V=3092.1(19)3,C 57 H 46 Cu 3 N 9 O 19.5,M r=1359.54,Z=2,D c=1.446 Mg/m 3,λ(MoKα)=0.71073,μ=1.101 mm-1,F(000)=1362,S=1.071,the final R=0.0718 and wR=0.11960 for 10705 observer reflections (I > 2σ(I)).The structure unit of the title complex consists of a mononuclear part and a di-nuclear part,and the three copper ions show three coordination modes.Each 6-coordinated geometry of the Cu atom is a distorted octahedral coordination geometry.The 3D supramolecular system is formed by the hydrogen bond O-H···O and π-π stacking interaction between neighboring single cells.The antibacterial activity of the title complex is also studied.     

Twisting of conjugated oligomers and polymers: case study of oligo- and polythiophene

Interring twisting (change in the dihedral angle between conjugated rings) of polythiophene was studied theoretically using periodic boundary conditions (PBC) at the B3LYP/6-31G(d) level. We find that the band gap of polymers is strongly dependent on the interring twist angle; yet twisting requires very little energy. A twist of 30 degrees increases the band gap by 0.75 eV in polythiophene, while requiring only 0.41 kcal mol(-1) per monomer unit. Such a small energetic value is of the order of crystal packing or van der Waals forces. These results are compared with calculations performed on model oligomers. Sexithiophene, its radical cations, and its dication are optimized at 0-180 degrees end-to-end twist angles (which correspond to 0-36 degrees interring dihedral angles) using the B3LYP/6-31G(d) method. The theoretical results suggest that the HOMO-LUMO gap, ionization potential, and charge distribution of oligomers are strongly dependent on twisting, whereas, similar to the case of polythiophene, twisting of neutral oligothiophenes costs very little energy. In the case of the radical cation, the lowest energy transition is shifted to a longer wavelength region on twisting, while the second-lowest energy transition is shifted to a shorter wavelength region. This implies that twisted, doped conducting polymers (modeled here by an oligomer radical cation), in contrast to planar, doped polymers, should be transparent within a certain optical window (in the far-visible region, at approximately 1.5 eV). This observation is explained on the basis of changes in the shape and overlap of the frontier molecular orbitals.     

An approach to control of band gap energy and photoluminescence upon band gap excitation in Pr(3+)-doped perovskites La(1/3)MO3 (M=Nb, Ta):Pr3+

We synthesized polycrystalline pristine and Pr(3+)-doped perovskites La(1/3)MO(3) (M = Nb, Ta):Pr(3+) and investigated their crystal structure, optical absorption, and luminescence properties. The optical band gap of La(1/3)NbO(3) (3.2 eV) is smaller than that of La(1/3)TaO(3) (3.9 eV), which is primarily due to the difference in electronegativity between Nb and Ta. In La(1/3)NbO(3):Pr(3+), the red emission assigned to the f-f transition of Pr(3+) from the excited (1)D(2) level to the ground (3)H(4) state upon band gap photoexcitation (near-UV) was observed, whereas the f-f transition of Pr(3+) with blue-green emission from the excited (3)P(0) level to the ground (3)H(4) state was quenched. On the other hand, in La(1/3)TaO(3):Pr(3+), the blue-green emission upon band gap photoexcitation was observed. Their differences in emission behavior are attributed to the energy level of the ground and excited states of 4f(2) for Pr(3+), relative to the energy levels of the conduction and valence bands, and the trapped electron state, which mediates the relaxation of electron from the conduction band to the excited state of Pr(3+). La(1/3)NbO(3):Pr(3+) is a candidate red phosphor utilizing near-UV LED chips (e.g., λ = 375 nm) as an excitation source.     

Synthesis,Crystal Structure and Thermal Behavior of a New 2D Barium（Ⅱ） Coordination Polymer with 1H-benzimi-dazole-5,6-dicarboxylate as the Single Ligand

The self-assembly of 1H-benzimidazole-5,6-dicarboxylic acid with barium chloride under hydrothermal conditions afforded a new 2D coordination polymer,[Ba2(L)(HL)Cl]n(1,L = 1H-benzimidazole-5,6-dicarboxylate),which was characterized by elemental analysis,infrared spectroscopy,thermogravimetric analysis,and single-crystal X-ray diffraction.Compound 1 is of monoclinic system,space group P21/c with a = 10.0145(6),b=25.6854(15),c=7.3116(4) ?,β = 99.4980(10)°,V = 1854.95(19)3,C18H9Ba2ClN4O8,Z = 4,Mr=719.42,Dc = 2.576 g/cm3,μ(MoKα) = 4.427 mm-1,F(000) = 1352,the final R = 0.0202 and wR=0.0465 for 3051 observed reflections with I > 2σ(I).It exhibits an interesting two-dimensional network structure and high thermal stability(up to 420 ℃).     

Optical band gap and conductivity measurements of polypyrrole-chitosan composite thin films

Electrical conductivity and optical properties of polypyrrole-chitosan（PPy-CHI） conducting polymer composites have been investigated to determine the optical transition characteristics and energy band gap of composite films.The two electrode method and I-V characteristic technique were used to measure the conductivity of the PPy-CHI thin films,and the optical band gap was obtained from their ultraviolet absorption edges.Depending upon experimental parameter,the optical band gap（E_g） was found within 1.30-2.32 eV as estimated from optical absorption data.The band gap of the composite films decreased as the CHI content increased.The room temperature electrical conductivity of PPy-CHI thin films was found in the range of 5.84×10^-7-15.25×10^-7 S·cm^-1 depending on the chitosan content.The thermogravimetry analysis（TGA） showed that the CHI can improve the thermal stability of PPy-CHI composite films.     

Optical properties of thermally evaporated 4-(4-nitrobenzalideneamino) antipyrine Schiff base thin films

4-(4-nitrobenzalideneamino) antipyrine (NBAA) have been synthesized by refluxed ethanolic solution of 4-aminoantipyrine and p-nitrobenzaldehyde for 4 h and characterized with various physico-chemical techniques. Thin films of NBAA have been prepared by the thermal deposition technique in a vacuum of 1.5 × 10⁻⁵ mbar onto optical flat glass substrates. X-ray diffraction patterns show amorphous nature for all NBAA thin films except UV irradiated thin film which shows amorphous nature with some crystallinity but with small amount. The optical constants of thermally deposited NBAA thin film were investigated in the wavelength range 200–2500 nm. The type of optical transition near the edge of the band gap is found to be indirect allowed transition. The effect of UV irradiation as well as the effect of annealing on the optical properties of NBAA thin films was investigated. The value of the energy gap for thin films under investigation is calculated and found to be 1.56 eV for as-deposited, 1.45 eV for annealed and 1.82 eV for UV irradiation.     

DFT calculation of the electronic and optical properties of Ag2PdO2 from X-ray and neutron crystallographic data

Electronic and optical properties of ternary silver palladium oxide (Ag₂PdO₂) are investigated using density functional theory. Two different possible approximations for the exchange correlation potentials were employed. The X-ray and neutron crystallographic data were optimized by minimization of the forces (1 mRy/a.u.) acting on the atoms. The electronic structure, electron space charge density, chemical bonding and optical dielectric were determined from the relaxed geometry seeking deep insight understanding of this material. Our calculated energy band gap (0.15 eV) shows a good agreement with the experimental value (0.18 eV).