New Molybdenum(VI) Phosphates: Synthesis, Characterization, and Calculations of Centrosymmetric Rb­MoO₂­PO₄ and Noncentrosymmetric Rb₄­Mo₅P₂­O₂₂

Two new molybdenum­(VI) phosphates, Rb­MoO₂­PO₄ and Rb₄­Mo₅P₂­O₂₂, have been synthesized by standard solid-state reactions, and their structures were determined by single-crystal X-ray diffraction. The former is centrosymmetric, whereas the latter is noncentrosymmetric and chiral. Their crystal structures both consist of corner- and edge-shared MoO₆ octahedra, PO₄ tetrahedra, and RbO_<i>n</i> (<i>n</i> = 8 or 10) polyhedra and exhibit three- and one-dimensional structures, respectively. Powder second-harmonic generation (SHG) measurements revealed an SHG efficiency of approximately 1.4 × KH₂PO₄ (KDP) for Rb₄­Mo₅P₂­O₂₂. Thermal analysis, infrared and UV–vis-NIR diffuse reflectance spectroscopy, and electronic band structure calculations were also performed on the reported materials. Crystal data are the following: Rb­MoO₂­PO₄, orthorhombic, space group <i>Fddd</i> (No. 70), <i>a</i> = 11.012(5) Å, <i>b</i> = 12.403(5) Å, <i>c</i> = 15.839(7) Å, <i>V</i> = 2163.3(16) ų, and <i>Z</i> = 16; Rb₄­Mo₅P₂­O₂₂, orthorhombic, space group <i>C</i>222₁ (No. 20), <i>a</i> = 6.5300(5) Å, <i>b</i> = 19.7834(18) Å, <i>c</i> = 17.3451(15) Å, <i>V</i> = 2240.7(3) ų, and <i>Z</i> = 4

Special _∞¹[OPb₂] Chains and _∞¹[O₂Pb₃] Ribbons Based on OPb₄ Anion-Centered Tetrahedra in Pb₂(O₄Pb₈)(BO₃)₃Br₃ and Pb₂(O₈Pb₁₂)(BO₃)₂Br₆

The structures of two new lead-containing oxyborate bromines, Pb₂(O₄Pb₈)­(BO₃)₃Br₃ (<b>1</b>) and Pb₂(O₈Pb₁₂)­(BO₃)₂Br₆ (<b>2</b>), are determined by single-crystal X-ray diffraction for the first time. Both of them crystallize in the space group <i>C</i>2<i>/c</i> of the monoclinic crystal system. Although the two compounds have the same type of fundmental building units (FBUs), the OPb₄ anion-centered tetrahedra and BO₃ triangles, they exhibit different connection modes. Compound <b>1</b> consists of single _∞¹[OPb₂] chains, while compound <b>2</b> possesses _∞¹[O₂Pb₃] ribbons. Interestingly, large Br atoms profoundly influence the conformation of polyions based on the OPb₄ anion-centered tetrahedra, resulting in single _∞¹[OPb₂] chains linked up by finite zweier chains with four OPb₄ tetrahedra via the opposite edges in compound <b>1</b> and _∞¹[O₂Pb₃] ribbons with sequential condensation of OPb₂ chains in compound <b>2</b>. A detailed description of the effect of large Br atoms on the conformation of polyions is discussed. IR spectroscopy, UV–vis–NIR diffuse reflectance spectroscopy, and thermal analysis are also performed on the reported materials

New Molybdenum(VI) Phosphates: Synthesis, Characterization, and Calculations of Centrosymmetric Rb­MoO₂­PO₄ and Noncentrosymmetric Rb₄­Mo₅P₂­O₂₂

Two new molybdenum­(VI) phosphates, Rb­MoO₂­PO₄ and Rb₄­Mo₅P₂­O₂₂, have been synthesized by standard solid-state reactions, and their structures were determined by single-crystal X-ray diffraction. The former is centrosymmetric, whereas the latter is noncentrosymmetric and chiral. Their crystal structures both consist of corner- and edge-shared MoO₆ octahedra, PO₄ tetrahedra, and RbO_<i>n</i> (<i>n</i> = 8 or 10) polyhedra and exhibit three- and one-dimensional structures, respectively. Powder second-harmonic generation (SHG) measurements revealed an SHG efficiency of approximately 1.4 × KH₂PO₄ (KDP) for Rb₄­Mo₅P₂­O₂₂. Thermal analysis, infrared and UV–vis-NIR diffuse reflectance spectroscopy, and electronic band structure calculations were also performed on the reported materials. Crystal data are the following: Rb­MoO₂­PO₄, orthorhombic, space group <i>Fddd</i> (No. 70), <i>a</i> = 11.012(5) Å, <i>b</i> = 12.403(5) Å, <i>c</i> = 15.839(7) Å, <i>V</i> = 2163.3(16) ų, and <i>Z</i> = 16; Rb₄­Mo₅P₂­O₂₂, orthorhombic, space group <i>C</i>222₁ (No. 20), <i>a</i> = 6.5300(5) Å, <i>b</i> = 19.7834(18) Å, <i>c</i> = 17.3451(15) Å, <i>V</i> = 2240.7(3) ų, and <i>Z</i> = 4

Special _∞¹[OPb₂] Chains and _∞¹[O₂Pb₃] Ribbons Based on OPb₄ Anion-Centered Tetrahedra in Pb₂(O₄Pb₈)(BO₃)₃Br₃ and Pb₂(O₈Pb₁₂)(BO₃)₂Br₆

The structures of two new lead-containing oxyborate bromines, Pb₂(O₄Pb₈)­(BO₃)₃Br₃ (<b>1</b>) and Pb₂(O₈Pb₁₂)­(BO₃)₂Br₆ (<b>2</b>), are determined by single-crystal X-ray diffraction for the first time. Both of them crystallize in the space group <i>C</i>2<i>/c</i> of the monoclinic crystal system. Although the two compounds have the same type of fundmental building units (FBUs), the OPb₄ anion-centered tetrahedra and BO₃ triangles, they exhibit different connection modes. Compound <b>1</b> consists of single _∞¹[OPb₂] chains, while compound <b>2</b> possesses _∞¹[O₂Pb₃] ribbons. Interestingly, large Br atoms profoundly influence the conformation of polyions based on the OPb₄ anion-centered tetrahedra, resulting in single _∞¹[OPb₂] chains linked up by finite zweier chains with four OPb₄ tetrahedra via the opposite edges in compound <b>1</b> and _∞¹[O₂Pb₃] ribbons with sequential condensation of OPb₂ chains in compound <b>2</b>. A detailed description of the effect of large Br atoms on the conformation of polyions is discussed. IR spectroscopy, UV–vis–NIR diffuse reflectance spectroscopy, and thermal analysis are also performed on the reported materials

Effect of Rigid Units on the Symmetry of the Framework: Design and Synthesis of Centrosymmetric NaBa₄(B₅O₉)₂F₂Cl and Noncentrosymmetric NaBa₄(AlB₄O₉)₂Br₃

Two similarly stoichiometric borate halides, NaBa₄(AlB₄O₉)₂Br₃ and NaBa₄(B₅O₉)₂F₂Cl, have been successfully designed and synthesized, and their structures were determined by single-crystal X-ray diffraction. Their crystal structures feature the [AlB₄O₉]_∞ and [B₅O₉]_∞ networks, respectively. NaBa₄(AlB₄O₉)₂Br₃ is noncentrosymmetric and crystallizes in polar space group <i>P</i>4₂<i>nm</i>, while NaBa₄(B₅O₉)₂F₂Cl is centrosymmetric and crystallizes in monoclinic space group <i>P</i>2₁/<i>n</i>. Powder second-harmonic generation (SHG) measurements reveal that NaBa₄(AlB₄O₉)₂Br₃ has an optical nonlinearity comparable to that of KH₂PO₄ (KDP) and is type I phase-matchable. In addition, infrared and UV–Vis–NIR diffuse reflectance spectroscopy, as well as electronic band structure calculations, were performed on the reported materials

Effect of Rigid Units on the Symmetry of the Framework: Design and Synthesis of Centrosymmetric NaBa₄(B₅O₉)₂F₂Cl and Noncentrosymmetric NaBa₄(AlB₄O₉)₂Br₃

Two similarly stoichiometric borate halides, NaBa₄(AlB₄O₉)₂Br₃ and NaBa₄(B₅O₉)₂F₂Cl, have been successfully designed and synthesized, and their structures were determined by single-crystal X-ray diffraction. Their crystal structures feature the [AlB₄O₉]_∞ and [B₅O₉]_∞ networks, respectively. NaBa₄(AlB₄O₉)₂Br₃ is noncentrosymmetric and crystallizes in polar space group <i>P</i>4₂<i>nm</i>, while NaBa₄(B₅O₉)₂F₂Cl is centrosymmetric and crystallizes in monoclinic space group <i>P</i>2₁/<i>n</i>. Powder second-harmonic generation (SHG) measurements reveal that NaBa₄(AlB₄O₉)₂Br₃ has an optical nonlinearity comparable to that of KH₂PO₄ (KDP) and is type I phase-matchable. In addition, infrared and UV–Vis–NIR diffuse reflectance spectroscopy, as well as electronic band structure calculations, were performed on the reported materials

Effect of Rigid Units on the Symmetry of the Framework: Design and Synthesis of Centrosymmetric NaBa₄(B₅O₉)₂F₂Cl and Noncentrosymmetric NaBa₄(AlB₄O₉)₂Br₃

Two similarly stoichiometric borate halides, NaBa₄(AlB₄O₉)₂Br₃ and NaBa₄(B₅O₉)₂F₂Cl, have been successfully designed and synthesized, and their structures were determined by single-crystal X-ray diffraction. Their crystal structures feature the [AlB₄O₉]_∞ and [B₅O₉]_∞ networks, respectively. NaBa₄(AlB₄O₉)₂Br₃ is noncentrosymmetric and crystallizes in polar space group <i>P</i>4₂<i>nm</i>, while NaBa₄(B₅O₉)₂F₂Cl is centrosymmetric and crystallizes in monoclinic space group <i>P</i>2₁/<i>n</i>. Powder second-harmonic generation (SHG) measurements reveal that NaBa₄(AlB₄O₉)₂Br₃ has an optical nonlinearity comparable to that of KH₂PO₄ (KDP) and is type I phase-matchable. In addition, infrared and UV–Vis–NIR diffuse reflectance spectroscopy, as well as electronic band structure calculations, were performed on the reported materials

First Principle Assisted Prediction of the Birefringence Values of Functional Inorganic Borate Materials

Prediction of the birefringence values of borate is very essential for developing new optical materials in UV range. In this paper, the birefringence values of five lead borates, Pb₈B₉O₂₁F, PbBiBO₄, Pb₃BO₄F, Pb₆B₃O₁₀Cl, and Pb₂BO₃F with network B–O structure or isolated BO₃ groups, are calculated by the first principle method. The calculations show that PbBiBO₄, Pb₃BO₄F, and Pb₂BO₃F have the large birefringence, greater than 0.1. Pb₂BO₃F, especially, is the first compound with large birefringence above 0.08 among positive uniaxial borate crystals. It is found that the parallel arrangement of fundamental building units is not the only light anisotropy active character. In the further research of Pb₂BO₃F, polarization disproportionation via a visualized model is first put forward for identifying the origin of large birefringence, which will be helpful to search for new optical materials with suitable birefringence

Linear and Nonlinear Optical Properties of K₃B₆O₁₀Br Single Crystal: Experiment and Calculation

The experimental and theoretical analysis of linear and nonlinear optical properties of K₃B₆O₁₀Br (KBOB), with a moderate birefringence that is suitable for UV coherent light generation and optical parametric oscillators, is presented in detail. The second-order nonlinear optical coefficients were measured by the Maker fringe method and the refractive indices dispersion curves were deduced by the minimum deviation technique at 16 different monochromatic sources from UV to NIR, and then the type I and type II phase-matching curves of second, third, and fourth harmonic generation (SHG, THG, and FHG) were calculated. Moreover, the correlations of crystallographic and crystallophysical axes were determined. On the basis of the density functional theory (DFT), the first-principles calculations have been employed successfully to study the structural and electronic properties of KBOB. In addition, to gain further insight into the structure–property relationship, the SHG density method was adopted to analyze the origin of the nonlinear optical response of KBOB