LnBSb₂O₈ (Ln = Sm, Eu, Gd, Tb): A Series of Lanthanide Boroantimonates with Unusual 3D Anionic Structures

A series of lanthanide boroantimonates, namely, LnBSb₂O₈ (Ln = Sm <b>1</b>, Eu <b>2</b>, Gd <b>3</b>, and Tb <b>4</b>) have been successfully synthesized by high temperature solid-state reactions for the first time. They are isostructural and feature novel three-dimensional (3D) frameworks composed of 2D [Sb₃O₁₂]^9– layers interconnected by 1D [SbBO₇]^6– chains with remaining BO₃ groups hanging on the walls of the 1D 6-membered-ring (MR) tunnels along the <i>a</i>-axis, and the lanthanide ions filled in the voids of the anionic structure. They exhibit high thermal stability (up to 900 °C). Luminescent studies suggest that compounds <b>1, 2,</b> and <b>4</b> have potential application as orange, red, and green light luminescent materials, respectively. Magnetic measurements reveal ferromagnetic coupling interactions in compound <b>3</b> and antiferromagnetic coupling interactions between magnetic centers in compounds <b>1</b>, <b>2</b>, and <b>4</b>

Ln₂Ga[B₃O₆(OH)]₂[B₇O₉(OH)₂](CH₃CO₂)₂ (Ln = Y, Sm, Eu, Gd, Dy): A Series of Lanthanide Galloborates Decorated by Acetate Anions

The first examples of mixed-anion lanthanide galloborates, namely, Ln₂Ga­[B₃O₆(OH)]₂[B₇O₉(OH)₂]­(CH₃CO₂)₂ [Ln = Y (<b>1</b>), Sm (<b>2</b>), Eu (<b>3</b>), Gd (<b>4</b>), Dy (<b>5</b>)], have been obtained through hydrothermal synthesis. The title compounds are isomorphic and belong to monoclinic space group <i>C</i>2/<i>c</i> (No. 15). Their structures possess [B₇O₁₃(OH)₂] borate layers further bridged with [B₃O₇] clusters to give a three-dimensional (3D) borate framework displaying two types of rhombus-like B₁₄O₁₄ 14-membered-ring (14-MR) channels along the <i>b</i> axis. The Ga³⁺ ions are octahedrally coordinated and located at one end of the B₁₄O₁₄ 14-MR channels, forming small tunnels of B₇Ga 8-MRs, which are filled by the Ln^III ions. The Ln ions and Ga cations are further held together by bridging acetate anions. It is worth noting that in these compounds there are two different types of borate clusters and two types of anions that are uncommon in the borates reported. Luminescent studies revealed the characteristic emission bands of Ln ions for compounds <b>2</b>–<b>5</b>, and the luminescent lifetimes are 3.6, 0.86, and 3.05 ns for compounds <b>2</b>, <b>3</b>, and <b>5</b>, respectively. Magnetic measurements suggest that there are antiferromagnetic interactions between magnetic centers for compounds <b>2</b>–<b>5</b>

K₂Pb₃(CO₃)₃F₂ and KCdCO₃F: Novel Fluoride Carbonates with Layered and 3D Framework Structures

Two new mixed metal fluoride carbonates, KCdCO₃F and K₂Pb₃(CO₃)₃F₂, have been synthesized by solvothermal and solid-state techniques. KCdCO₃F crystallizes in the acentric nonpolar space group <i>P</i>6̅<i>m</i>2, and its structure features a three-dimensional anionic framework in which the CdCO₃ layers are further interconnected by bridging F^– anions with the negative charge balanced by K⁺ cations. K₂Pb₃(CO₃)₃F₂ crystallizes in the centrosymmetric space group <i>P</i>6₃/<i>mmc</i>, and its structure exhibits a layered anionic skeleton featuring corner-shared PbO₆F and PbO₆F₂ polyhedra. UV–vis diffuse reflectance spectroscopy studies show that the short-wavelength absorption edges of KCdCO₃F and K₂Pb₃(CO₃)₃F₂ are 227 and 287 nm, respectively. The second harmonic generation (SHG) measurement reveals that KCdCO₃F is a phase-matchable material for generation of doubled-frequency light at both 532 and 266 nm, with a large SHG response of approximately 5.2 times that of KH₂PO₄ (KDP) at 532 nm and a moderate SHG response of approximately 0.75 times that of β-BaB₂O₄ (BBO) at 266 nm. Therefore, it is a promising UV material for fourth harmonic generation on a 1064 nm Q-switched Nd:YAG laser

Ln₂Ga[B₃O₆(OH)]₂[B₇O₉(OH)₂](CH₃CO₂)₂ (Ln = Y, Sm, Eu, Gd, Dy): A Series of Lanthanide Galloborates Decorated by Acetate Anions

The first examples of mixed-anion lanthanide galloborates, namely, Ln₂Ga­[B₃O₆(OH)]₂[B₇O₉(OH)₂]­(CH₃CO₂)₂ [Ln = Y (<b>1</b>), Sm (<b>2</b>), Eu (<b>3</b>), Gd (<b>4</b>), Dy (<b>5</b>)], have been obtained through hydrothermal synthesis. The title compounds are isomorphic and belong to monoclinic space group <i>C</i>2/<i>c</i> (No. 15). Their structures possess [B₇O₁₃(OH)₂] borate layers further bridged with [B₃O₇] clusters to give a three-dimensional (3D) borate framework displaying two types of rhombus-like B₁₄O₁₄ 14-membered-ring (14-MR) channels along the <i>b</i> axis. The Ga³⁺ ions are octahedrally coordinated and located at one end of the B₁₄O₁₄ 14-MR channels, forming small tunnels of B₇Ga 8-MRs, which are filled by the Ln^III ions. The Ln ions and Ga cations are further held together by bridging acetate anions. It is worth noting that in these compounds there are two different types of borate clusters and two types of anions that are uncommon in the borates reported. Luminescent studies revealed the characteristic emission bands of Ln ions for compounds <b>2</b>–<b>5</b>, and the luminescent lifetimes are 3.6, 0.86, and 3.05 ns for compounds <b>2</b>, <b>3</b>, and <b>5</b>, respectively. Magnetic measurements suggest that there are antiferromagnetic interactions between magnetic centers for compounds <b>2</b>–<b>5</b>

Silver Pyroarsonates Obtained from Ag(I)-Mediated in Situ Condensation of Aryl Arsonate Ligands under Solvothermal Conditions

Four new layered silver­(I) organoarsonates, namely, [Ag₃(L³)­(CN)] (<b>1</b>) (H₂L³ = (PhAsO₂H)₂O), [Ag₃(L⁴)­(CN)] (<b>2</b>) (H₂L⁴ = (2-NO₂-C₆H₄-AsO₂H)₂O), [Ag₃(HL⁵)­(H₂L⁵)] (<b>3</b>) (H₃L⁵ = 3-NO₂-4-OH-C₆H₃-AsO₃H₂) and [Ag₂(HL⁵)] (<b>4</b>), were synthesized under solvothermal conditions. During the preparations of <b>1</b> and <b>2</b>, condensation of organoarsonate ligands (H₂L¹ = Ph-AsO₃H₂; H₂L² = 2-NO₂-C₆H₄-AsO₃H₂) and the decomposition of acetonitrile molecules to cyanide anions occurred. Single crystals of H₂L⁴ ligand and compounds <b>1</b>–<b>4</b> were isolated, and their crystal structures have been determined by single crystal X-ray diffraction studies. In <b>1</b>, the one-dimensional (1D) chains based on Ag­(I) ions and {L³}^2– anions are further interconnected by CN^– into two-dimensional (2D) layers. In <b>2</b>, adjacent Ag­(I) ions within the silver­(I) organoarsonate layer are further bridged by μ₄-CN^– anions with very short Ag···Ag contacts. In <b>3</b>, the hexanuclear {Ag₆O₁₂} clusters are interconnected by bridging organoarsonate ligands into a silver­(I) arsonate hybrid layer. In <b>4</b>, the right-handed {Ag₄O₄} chains are further interconnected by organoarsonate ligands as well as additional Ag–O–Ag bridges into a novel silver­(I) arsonate layer. Compounds <b>1</b> and <b>2</b> display red and orange-red emissions, respectively, which may be assigned to be an admixture of ligand-to-metal charge transfer (LMCT) and metal-centered (4d-5s/5p) transitions perturbed by Ag­(I)···Ag­(I) interactions. Upon cooling from room temperature to 10 K, compound <b>1</b> exhibits interesting temperature-dependent emissions

A Series of Mixed-Metal Germanium Iodates as Second-Order Nonlinear Optical Materials

A series of new compounds in the A/Ae-Ge⁴⁺-IO₃ system, namely, A₂Ge­(IO₃)₆ (A = Li, Na, Rb, or Cs) and BaGe­(IO₃)₆(H₂O), have been obtained by introducing GeO₆ octahedra into a ternary metal iodate system. The structures of all five new compounds feature a zero-dimensional [Ge­(IO₃)₆]^2– anion composed of a GeO₆ octahedron connecting with six IO₃ groups, the alkali or alkali-earth cations acting as spacers between these anions and maintaining charge balance. Interestingly, the isomeric Li₂Ge­(IO₃)₆ and Na₂Ge­(IO₃)₆ are noncentrosymmetric (NCS), whereas the isostructural Rb₂Ge­(IO₃)₆ and Cs₂Ge­(IO₃)₆ are centrosymmetric. BaGe­(IO₃)₆(H₂O) is the first NCS alkali-earth germanium iodate reported. Powder second-harmonic generation (SHG) measurements show that Li₂Ge­(IO₃)₆, Na₂Ge­(IO₃)₆, and BaGe­(IO₃)₆(H₂O) crystals are phase-matchable and display very large SHG signals that are approximately 32, 15, and 12 times that of KH₂PO₄, respectively, under 1064 nm radiation and 2, 0.8, and 0.8 times that of KTiOPO₄, respectively, under 2.05 mm laser radiation. The compounds show high thermal stability and a large laser damage threshold, indicating their potential applications as nonlinear optical (NLO) materials in visible and infrared spectral regions. Measurement of optical properties, thermal analysis, and theoretical calculations of the SHG origin have been performed. Our studies indicate that introducing non-second-order Jahn–Teller-distortive MO₆ octahedra into metal iodate systems can also lead to good mixed-metal iodate NLO materials

A Series of Mixed-Metal Germanium Iodates as Second-Order Nonlinear Optical Materials

A series of new compounds in the A/Ae-Ge⁴⁺-IO₃ system, namely, A₂Ge­(IO₃)₆ (A = Li, Na, Rb, or Cs) and BaGe­(IO₃)₆(H₂O), have been obtained by introducing GeO₆ octahedra into a ternary metal iodate system. The structures of all five new compounds feature a zero-dimensional [Ge­(IO₃)₆]^2– anion composed of a GeO₆ octahedron connecting with six IO₃ groups, the alkali or alkali-earth cations acting as spacers between these anions and maintaining charge balance. Interestingly, the isomeric Li₂Ge­(IO₃)₆ and Na₂Ge­(IO₃)₆ are noncentrosymmetric (NCS), whereas the isostructural Rb₂Ge­(IO₃)₆ and Cs₂Ge­(IO₃)₆ are centrosymmetric. BaGe­(IO₃)₆(H₂O) is the first NCS alkali-earth germanium iodate reported. Powder second-harmonic generation (SHG) measurements show that Li₂Ge­(IO₃)₆, Na₂Ge­(IO₃)₆, and BaGe­(IO₃)₆(H₂O) crystals are phase-matchable and display very large SHG signals that are approximately 32, 15, and 12 times that of KH₂PO₄, respectively, under 1064 nm radiation and 2, 0.8, and 0.8 times that of KTiOPO₄, respectively, under 2.05 mm laser radiation. The compounds show high thermal stability and a large laser damage threshold, indicating their potential applications as nonlinear optical (NLO) materials in visible and infrared spectral regions. Measurement of optical properties, thermal analysis, and theoretical calculations of the SHG origin have been performed. Our studies indicate that introducing non-second-order Jahn–Teller-distortive MO₆ octahedra into metal iodate systems can also lead to good mixed-metal iodate NLO materials

Series of SHG Materials Based on Lanthanide Borate–Acetate Mixed Anion Compounds

The first examples of lanthanide borate–acetate mixed anion compounds, namely, Ln₂(CH₃CO₂)₂[B₅O₉(OH)]·H₂O (Ln = La <b>1</b>; Ce <b>2</b>; Pr <b>3</b>), were synthesized under hydrothermal conditions. These compounds are isostructural and crystallize in polar space group <i>Cc</i>. They display a unique three-dimensional (3D) framework built by a 3D network of lanthanide borate further decorated by acetate anions. The borate anion exhibits a 2D layer in the <i>ac</i> plane with large 9-member rings (MRs) which are filled by lanthanide­(III) ions into a {Ln­[B₅O₉(OH)]}⁻ 2D layer. Adjacent {Ln­[B₅O₉(OH)]}⁻ layers are bridged by remaining lanthanide (III) ions to form a 3D network of lanthanide borate. It is noteworthy that Ln₂(CH₃CO₂)₂[B₅O₉(OH)]·H₂O (Ln = La <b>1</b>; Ce <b>2</b>; Pr <b>3</b>) can be changed into Ln₂(CH₃CO₂)₂[B₅O₉(OH)] (Ln = La <b>4</b>; Ce <b>5</b>; Pr <b>6</b>) under heating at 500 K. Compounds <b>1</b>–<b>4</b> display moderate SHG signals of about 2.0, 1.0, 1.4, and 2.5 times that of KH₂PO₄, respectively, and they are phase matchable. Their SHG responses mainly arise from the synergistic polarization effects of both asymmetric borate clusters and π-conjugated CH₃COO^– anions

Series of SHG Materials Based on Lanthanide Borate–Acetate Mixed Anion Compounds

The first examples of lanthanide borate–acetate mixed anion compounds, namely, Ln₂(CH₃CO₂)₂[B₅O₉(OH)]·H₂O (Ln = La <b>1</b>; Ce <b>2</b>; Pr <b>3</b>), were synthesized under hydrothermal conditions. These compounds are isostructural and crystallize in polar space group <i>Cc</i>. They display a unique three-dimensional (3D) framework built by a 3D network of lanthanide borate further decorated by acetate anions. The borate anion exhibits a 2D layer in the <i>ac</i> plane with large 9-member rings (MRs) which are filled by lanthanide­(III) ions into a {Ln­[B₅O₉(OH)]}⁻ 2D layer. Adjacent {Ln­[B₅O₉(OH)]}⁻ layers are bridged by remaining lanthanide (III) ions to form a 3D network of lanthanide borate. It is noteworthy that Ln₂(CH₃CO₂)₂[B₅O₉(OH)]·H₂O (Ln = La <b>1</b>; Ce <b>2</b>; Pr <b>3</b>) can be changed into Ln₂(CH₃CO₂)₂[B₅O₉(OH)] (Ln = La <b>4</b>; Ce <b>5</b>; Pr <b>6</b>) under heating at 500 K. Compounds <b>1</b>–<b>4</b> display moderate SHG signals of about 2.0, 1.0, 1.4, and 2.5 times that of KH₂PO₄, respectively, and they are phase matchable. Their SHG responses mainly arise from the synergistic polarization effects of both asymmetric borate clusters and π-conjugated CH₃COO^– anions

LiGa₂PS₆ and LiCd₃PS₆: Molecular Designs of Two New Mid-Infrared Nonlinear Optical Materials

To simultaneously maintain large second harmonic generation (SHG) and high laser damage thresholds (LDTs) for mid- and far-infrared (IR) nonlinear optical (NLO) materials is very challenging and significant in laser science and technology. Using a chemical substitution strategy, two new mid-infrared NLO materials based on metal thiophosphates, namely, LiGa₂PS₆ and LiCd₃PS₆, have been obtained from AgGa₂PS₆. They both crystallize in the <i>Cc</i> space group but exhibit different structures. LiGa₂PS₆ is isostructural with the parent AgGa₂PS₆, displaying a three-dimensional (3D) anionic framework of [Ga₂PS₆]⁻ composed of [Ga₂S₆]^6– chains and PS₄ tetrahedra with the 1D triangular-shaped tunnels filled by Li⁺ ions. LiCd₃PS₆ features a 3D anionic framework of [Cd₃S₆]^6– composed of 2D layers of [Cd₂S₅]^6– and the bridging CdS₄ units with 1D tunnels along the <i>b</i>-axis filled by [LiPS₆]^6– chains. Remarkably, both materials display large band gaps of 3.15 eV (for LiGa₂PS₆) and 2.97 eV (for LiCd₃PS₆), and keep a good balance between strong SHG responses (0.5–0.8 × AgGaS₂ at 1910 nm in the particle range 53–71 μm) and high LDTs (5.5–10.4 × AgGaS₂); therefore both crystals are new promising mid-IR NLO materials