PbPt(IO3)6(H2O): a new polar material with two types of stereoactive lone-pairs and a very large SHG response

(Me4N)2[Pt(CO3)2(OH)2]: The Isolated PtIVO6 Carbonato-Complex

The first fully inorganic Pt(IV) carbonato-complex trans-[Pt(CO3)2(OH)2]2- with a {PtO6} coordination sphere was isolated as the (Me4N)2[Pt(CO3)2(OH)2] (1) salt. The compound 1 was characterized using single-crystal and powder X-ray diffraction, Raman spectroscopy, infrared spectroscopy (FTIR), electrospray ionization mass spectrometry (ESI-MS), nuclear magnetic resonance spectroscopy (NMR), and thermogravimetric analysis (TG). Density functional theory (DFT) calculations were also performed to analyze the spectral features of the complex. 1 crystallizes in the triclinic system (P-1) with a Z of 1. The trans-[Pt(CO3)2(OH)2]2- anion has axial hydroxo ligands and κ2-CO3 ligands, which form an equatorial plane. This anionic complex exhibits notable stability in aqueous solutions, while the axial hydroxo ligand can be readily modified, as exemplified by the acylation of the trans-[Pt(CO3)2(OH)2]2- into trans-[Pt(CO3)2(OAc)2]2- anion. Furthermore, it has been shown that rigid and glittering platinum coatings can be electrochemically deposited from an aqueous solution of 1 without the addition of surfactants.

Unprecedented boat-shaped [Mo2O5(IO3)4]2- polyanions induced a strong second harmonic generation response

The first organic-inorganic hybrid guanidine molybdenyl iodate [C(NH₂)₃]₂Mo₂O₅(IO₃)₄·2H₂O was successfully synthesized via an improved moderate hydrothermal method. It features an unprecedented boat-shaped zero-dimensional [Mo₂O₅(IO₃)₄]^2- polyanion cluster, which induces a wide band gap, moderate birefringence and strong second harmonic generation response, indicating that it is a potential nonlinear optical material.

BaI3O9H: a new alkaline-earth metal hydroxy iodate with two groups

A new alkali metal hydroxyl iodate BaI3O9H with a three-dimensional network structure and a moderate birefringence of 0.073 at 1064 nm.

Na7(IO3)(SO4)3: the first noncentrosymmetric alkaline-metal iodate-sulfate with isolated [IO3] and [SO4] units

Metal iodates are of current research interest because of their potential application as nonlinear optical crystals but the exploration of new iodates is mainly concentrated on complex cation iodates. In contrast, iodates with multiple anion groups are rarely reported. In this communication, the first noncentrosymmetric alkaline-metal iodate-sulfate, Na₇(IO₃)(SO₄)₃ has been designed, synthesized and characterized.

[GaF(H2O)][IO3F]: a promising NLO material obtained by anisotropic polycation substitution

A novel salt-inclusion fluoroiodate [GaF(H2O)][IO3F] derived from CsIO2F2 was ingeniously obtained through anisotropic polycation substitution. Because the catenulate [GaF(H2O)]2+ framework serves as a template for the favorable assembly of the polar [IO3F]2- groups and contributes to the nonlinear coefficient, [GaF(H2O)][IO3F] exhibits a greatly improved second-harmonic generation (SHG) effect of 10 times that of KH2PO4 (KDP) and a considerable band gap of 4.34 eV compared to the parent compound CsIO2F2 (3 × KDP, 4.5 eV). Particularly, to the best of our knowledge, [GaF(H2O)][IO3F] has the largest laser-induced damage threshold (LDT) of 140 × AgGgS2 of the reported iodates. All these results signify that [GaF(H2O)][IO3F] is a promising nonlinear optical (NLO) crystal. This work also proposes that anisotropic polycation substitution is an effective approach to optimize the SHG effect and develop excellent NLO materials.

[o-C5 H4 NHOH]2 [I7 O18 (OH)]⋅3 H2 O: An Organic-Inorganic Hybrid SHG Material Featuring an [I7 O18 (OH)] ∞ 2 - Branched Polyiodate Chain

An organic-inorganic hybrid polyiodate, namely, [o-C₅ H₄ NHOH]₂ [I₇ O₁₈ (OH)]⋅3 H₂ O (I), featuring a novel branched polyiodate chain has been obtained by evaporation method. [o-C₅ H₄ NHOH]₂ [I₇ O₁₈ (OH)]⋅3 H₂ O (I) crystalizes in the polar space group Ia and features an [I₇ O₁₈ (OH)] ∞ 2 - branched polyiodate chain in which [I₃ O₉ ]^3- trimers are grafted on the same side of the one-dimensional (1D) chain based on [I₄ O₁₁ (OH)]^3- tetramers. The asymmetric organic amine groups are beneficial to the polymerization of iodate groups and inducing the formation of the non-centrosymmetric (NCS) structure. Compound I exhibits a rather large Second-Harmonic- Generation (SHG) signal of 8.5×KH₂ PO₄ (KDP) upon 1064 nm laser radiation, a moderate band gap of 3.90 eV and a high laser-induced-damage-threshold (LIDT) of 182.34 MW cm^-2 , hence it is a promising new SHG material. The relationship between the structures of the organic amine groups and the overall structures has been also analyzed.

SrTi(IO3)6·2H2O and SrSn(IO3)6: distinct arrangements of lone pair electrons leading to large birefringences

Three new iodates SrTi(IO₃)₆·2H₂O, (H₃O)₂Ti(IO₃)₆, and SrSn(IO₃)₆ have been synthesized via a facile hydrothermal method. The three compounds have zero-dimensional crystal structures composed of one [MO₆]⁸⁻ (M = Ti, Sn) octahedron connected with six [IO₃]⁻ trigonal pyramids. However, the particular coordination of Sr²⁺ cations results in distinct arrangements of lone pair electrons in an [IO₃]⁻ trigonal pyramid, which leads to large birefringences. More importantly, this work enriches the species crystal chemistry for [M(IO₃)₆]²⁻ (M = Ti, Sn) clusters-containing iodates.

The distinct arrangements of [IO₃]⁻ trigonal pyramids lead to larger birefringences in SrTi(IO₃)₆·2H₂O and SrSn(IO₃)₆ than that in (H₃O)₂Ti(IO₃)₆.

On the crystal chemistry of inorganic nitrides: crystal-chemical parameters, bonding behavior, and opportunities in the exploration of their compositional space

The scarcity of nitrogen in Earth's crust, combined with challenging synthesis, have made inorganic nitrides a relatively unexplored class of compounds compared to their naturally abundant oxide counterparts. To facilitate exploration of their compositional space via a priori modeling, and to help a posteriori structure verification not limited to inferring the oxidation state of redox-active cations, we derive a suite of bond-valence parameters and Lewis acid strength values for 76 cations observed bonding to N3-, and further outline a baseline statistical knowledge of bond lengths for these compounds. Examination of structural and electronic effects responsible for the functional properties and anomalous bonding behavior of inorganic nitrides shows that many mechanisms of bond-length variation ubiquitous to oxide and oxysalt compounds (e.g., lone-pair stereoactivity, the Jahn-Teller and pseudo Jahn-Teller effects) are similarly pervasive in inorganic nitrides, and are occasionally observed to result in greater distortion magnitude than their oxide counterparts. We identify promising functional units for exploring uncharted chemical spaces of inorganic nitrides, e.g. multiple-bond metal centers with promise regarding the development of a post-Haber-Bosch process proceeding at milder reaction conditions, and promote an atomistic understanding of chemical bonding in nitrides relevant to such pursuits as the development of a model of ion substitution in solids, a problem of great relevance to semiconductor doping whose solution would fast-track the development of compound solar cells, battery materials, electronics, and more.

Two deep-ultraviolet nonlinear optical monolayers obtained by a template-optimized design strategy

We obtained two two-dimentional deep-ultraviolet nonlinear optical layers with a large band gap and proper second harmonic generation by a template-optimized design strategy.

Na4SnS4 and Na4SnSe4 exhibiting multifunctional physicochemical performances as potential infrared nonlinear optical crystals and sodium ion conductors

Na₄SnS₄ and Na₄SnSe₄ exhibiting excellent physicochemical performances as potential IR NLO crystals and sodium ion conductors were systematically studied.

A study of composition effects on the bandgaps in a series of new alkali metal aluminum/gallium iodates

Four new alkali metal aluminum/gallium iodates, namely A₂M(IO₃)₄(H_0.5IO₃)₂ (A = K, Rb and M = Al, Ga), have been successfully synthesized via a hydrothermal reaction and structurally characterized through single-crystal X-ray diffraction analysis. These compounds are isostructural and crystallize in the P1[combining macron] space group (no. 2) with one formula unit in each unit cell. The rare half-protonated H_0.5IO₃ building units were identified, and their structure feature isolated [M(IO₃)₄(H_0.5IO₃)₂]^2- anions, which are separated by alkali metal cations. The optical diffuse reflectance spectroscopy measurements associated with the Tauc analysis showed direct energy gaps, which are in good agreement with the theoretical calculation prediction. Moreover, this study also indicates that the electronic properties of these compounds are mainly determined by the IO₃ and H_0.5IO₃ anionic units, and the alkali metal cations show a remarkable effect on their energy gap values, whereas the impacts of the group 13 elements aluminum and gallium are insignificant.

From BiF3 to BiF3·H2O: diverse Bi(iii) coordination for structural transformation and birefringence regulation

BiF₃·H₂O with unprecedented BiF₉ building blocks was synthesized, which exhibits a near-isotropic Bi³⁺ coordination and inert lone pair activity.

Synthesis, structure and characterization of M(IO3)2(HIO3) (M = Ca, Sr) as new anhydrous alkaline earth metal bis-iodate hydrogeniodate compounds

Two new metal iodates, namely, M(IO₃)₂(HIO₃) (M = Ca, Sr), were successfully synthesized by the hydrothermal method, and their structures were determined by single-crystal X-ray diffraction. They were found to be isostructural, and crystallized in the monoclinic space group P2₁/n with the lattice parameters: a = 6.9647(14) Å, b = 15.719(3) Å, c = 7.2042(14) Å, β = 92.76(3)°, Z = 4 for Ca(IO₃)₂(HIO₃), and a = 7.0697(14) Å, b = 15.986(3) Å, c = 7.3802(15) Å, β = 93.13(3)°, Z = 4 for Sr(IO₃)₂(HIO₃). The structure featured a [HIO₃]·[IO₃]^- complex with strong intermolecular interactions, and it was composed of [IO₃]^- anions and [HIO₃]·[IO₃]^- complexes interconnected by Ca²⁺ or Sr²⁺ cations. The two compounds were characterized by X-ray diffraction, IR and Raman spectroscopies, UV-Vis diffuse reflectance spectroscopy, thermogravimetry and differential scanning calorimetry as well as by theoretical calculations.

Li2ZnGeS4: a promising diamond-like infrared nonlinear optical material with high laser damage threshold and outstanding second-harmonic generation response

A promising IR nonlinear optical material Li₂ZnGeS₄ with a diamond-like configuration and high optical performance is reported.

ABaSbQ3 (A = Li, Na; Q = S, Se): diverse arrangement modes of isolated SbQ3 ligands regulating the magnitudes of birefringences

The interrelation of arrangement modes of isolated SbQ₃ ligands on structures and birefringences has been systematically studied in series of chalcogenides.

Syntheses, Structures, and Properties of Non-Centrosymmetric Quaternary Tellurates Bi MTeO6 ( M = Al, Ga)

Single crystals of two new metal tellurates Bi MTeO₆ ( M = Al, Ga) with a honeycomb layered structure were obtained by the molten flux method and characterized. The Bi MTeO₆ compounds both crystallize into a non-centrosymmetric trigonal space group of P312 (no. 149) with cell parameters of a = 5.0667(8) Å, c = 4.9920(16) Å and a = 5.107(3) Å, c = 4.932(6) Å, respectively. The non-centrosymmetry of BiAlTeO₆ and BiGaTeO₆ originates from the packing order of the octahedra. In these two structures, TeO₆ octahedra and MO₆ octahedra share edges and form a honeycomb open-framework with [Te MO₆]_∞ layers. The layers of [ MTeO₆]_∞ and [BiO₆]_∞ alternate and are connected along the c-axis by corner-sharing oxygen atoms to form the three-dimensional framework. The chiral compound BiGaTeO₆ exhibits a powder second harmonic generation (SHG) response of ∼0.2 times that of potassium dihydrogen phosphate (KDP) and an absorption edge of 355 nm.

K8Ce2I18O53: a novel potassium cerium(iv) iodate with enhanced visible light driven photocatalytic activity resulting from polar zero dimensional [Ce(IO3)8]4- units

Hydrothermally grown iodate, K₈Ce₂I₁₈O₅₃, featuring polar 0D [Ce(IO₃)₈]^4- units, has shown the highest visible light driven (VLD) photocatalytic activity in metal iodates reported before. The enhanced VLD photocatalytic property results from a synergistic effect between the narrow band gap and polar 0D [Ce(IO₃)₈]^4- units, as confirmed using first principles calculations.

Remarkable multimember-ring configurations in a new family of Na7MIISb5S12 (MII = Zn, Cd, Hg) exhibiting various three-dimensional tunnel structures

A new series of thioantimonates featuring the newly discovered trimer (M^II/Sb)₃S₉ and 12 + 12-MR configurations are verified as potential IR birefringent materials.

Pb3(SeO3)Br4: a new nonlinear optical material with enhanced SHG response designedviaan ion-substitution strategy

A new NLO material has been designedviaion-substitution from a similar structure. It shows an enhanced SHG response equalling to that of KH₂PO₄(KDP) and a high laser damage threshold of 67 MW cm⁻¹.

Two Barium Gold Iodates: Syntheses, Structures, and Properties of Polar BaAu(IO3)5 and Nonpolar HBa4Au(IO3)12 Materials

Two new barium gold iodates, namely, BaAu(IO₃)₅ and HBa₄Au(IO₃)₁₂, have been prepared. BaAu(IO₃)₅ crystallizes in the polar space group Pca2₁, whereas HBa₄Au(IO₃)₁₂ crystallizes in the centrosymmetric space group P2₁/c. BaAu(IO₃)₅ consists of unique polar [Au(IO₃)₄]^- anions whose four iodate groups are located at both sides of the AuO₄ plane and the polarity points in the [001̅] direction. BaAu(IO₃)₅ displays strong second-harmonic-generation (SHG) effects about 0.6KTiOPO₄ (KTP) and is phase-matchable. Thermal properties, optical spectra analyses, and theoretical calculations are also reported.

Two deep-ultraviolet nonlinear optical alkaline-earth metal borates based on different types of oxoboron clusters

Two non-centrosymmetric alkaline-earth metal borates were synthesized, showing the layered structures constructed from different oxoboron clusters and potentially new candidates for deep-UV NLO materials.

Na6Si3S8O: the first example of a sulfide silicate exhibiting unusual tri-polymerized [Si3S8O]6−units without S–O bonds

A new sulfide silicate – Na₆Si₃S₈O – featuring novel tri-polymerized [Si₃S₈O]⁶⁻units without common S–O bonds has been verified as a promising birefringent material.

The first quaternary diamond-like semiconductor with 10-membered LiS4rings exhibiting excellent nonlinear optical performances

New DLS–Li₄HgGe₂S₇with novel 10-MR LiS₄rings and excellent performances(concurrently large SHG coefficient and impressive LDT) is reported.

New Series of Polar and Nonpolar Platinum Iodates A2Pt(IO3)6 (A = H3O, Na, K, Rb, Cs)

A new series of platinum iodates, namely, α-(H3O)2Pt(IO3)6, β-(H3O)2Pt(IO3)6, and A2Pt(IO3)6 (A = Na, K, Rb, Cs), have been synthesized. Interestingly, among these six stoichiometrically identical compounds, α-(H3O)2Pt(IO3)6 is polar, whereas other compounds are nonpolar and centrosymmetric. They all consist of zero-dimensional [Pt(IO3)6](2-) molecular units separated by H3O(+) or A(+) cations. All of the lone electron pairs of the IO3(-) groups are aligned and almost point to one direction for α-(H3O)2Pt(IO3)6, whereas IO3(-) groups are located trans to each other in other compounds. The material, α-(H3O)2Pt(IO3)6, exhibits very strong second harmonic generation (SHG) effects, approximately 1.2 × KTiOPO4 (KTP), and is phase-matchable. Thermogravimetric analysis, elemental analysis, infrared spectra, UV-vis spectra, nonlinear optical properties, and theoretical calculations are also reported.

K2 Au(IO3)5 and β-KAu(IO3)4: Polar Materials with Strong SHG Responses Originating from Synergistic Effect of AuO4 and IO3 Units

Two new polar potassium gold iodates, namely, K2 Au(IO3)5 (Cmc21) and β-KAu(IO3)4 (C2), have been synthesized and structurally characterized. Both compounds feature zero-dimensional polar [Au(IO3)4](-) units composed of an AuO4 square-planar unit coordinated by four IO3(-) ions in a monodentate fashion. In β-KAu(IO3)4, isolated [Au(IO3)4](-) ions are separated by K(+) ions, whereas in K2 Au(IO3)5, isolated [Au(IO3)4](-) ions and non-coordinated IO3(-) units are separated by K(+) ions. Both compounds are thermally stable up to 400 °C and exhibit high transmittance in the NIR region (λ=800-2500 nm) with measured optical band gaps of 2.65 eV for K2 Au(IO3 )5 and 2.75 eV for β-KAu(IO3)4. Powder second-harmonic generation measurements by using λ=2.05 μm laser radiation indicate that K2 Au(IO3)5 and β-KAu(IO3)4 are both phase-matchable materials with strong SHG responses of approximately 1.0 and 1.3 times that of KTiOPO4, respectively. Theoretical calculations based on DFT methods confirm that such strong SHG responses originate from a synergistic effect of the AuO4 and IO3 units.

An outstanding second-harmonic generation material BiB2O4F: exploiting the electron-withdrawing ability of fluorine

The fluorine atoms in BiB₂O₄F withdraw the non-bonding electrons of Bi³⁺ and thus strongly increase the SHG efficiency.

Bi2Te(IO3)O5Cl: a novel polar iodate oxychloride exhibiting a second-order nonlinear optical response

A novel iodate oxychloride Bi₂Te(IO₃)O₅Cl with a second-order nonlinear optical response originating from constructive stacking of dipole moments of IO₃.

Series of lead oxide hydroxide nitrates obtained by adjusting the pH values of the reaction systems

A series of lead(II) nitrates have been synthesized by a hydrothermal method and adjusting the pH values of the reaction systems. Pb20O6(OH)16(NO3)12 and Pb2O(OH)NO3, crystallize in the centrosymmetric space group P1̅ and Pbca, respectively. The structure of Pb20O6(OH)16(NO3)12 features infinite cationic chains of [Pb20O6(OH)16]∞ running along c axis, and the nitrate groups as the counterions reside between adjacent chains, while the structure of Pb2O(OH)NO3 can be described as alternate stacking of cationic [Pb2O(OH)]∞ layers with anionic [NO3](-) layers along [001] direction by the weak Pb-O bonds, forming a 3D framework with 1D tunnels of 12-member rings (MRs). [Pb4(OH)4](NO3)4, crystallizing in the noncentrosymmetric space group Cc, has been studied as the nonlinear optical material for the first time. The second harmonic generation (SHG) measurement indicates that the SHG responses of [Pb4(OH)4](NO3)4 are 0.7 times that of KDP. Theoretical calculations confirmed the SHG efficiency of [Pb4(OH)4](NO3)4 originates from the cooperative effect of NO3(-) groups and lead oxygen polyhedras in the structure. Meanwhile, the relationship between pH value and ratio of Pb/OH(-) in the molecules presents a positive correlation, which results in the diversity of these structures under different pH value.