"Two in one": an unprecedented mixed anion, Ba(CNO)(CNO), with the coexistence of isolated sp and spπ-conjugated groups.

The combination of different types of π-conjugated anions into one structure can lead to multifunctional materials with intriguing properties. Herein, we successfully developed a new mixed anion compound, Ba(CNO)(CNO) (I), containing two types of π-conjugated groups, planar (CNO) six-membered rings and linear (CNO) units, for the first time. The compound I exhibits the wide bandgap of 4.

BaSrPbOCl: the first alkali-earth metal lead(ii) oxyhalide with an intriguing multimember-ring layer.

The first alkali-earth metal lead(ii) oxyhalide BaSrPbOCl characterized by fascinating multimember-ring layers has been discovered. Theoretical and experimental investigations illustrate that BaSrPbOCl exhibits a moderate band gap of 3.09 eV, incongruent melting behavior and birefringence of 0.

Facile Growth of an Ultraviolet Hydroisocyanurate Crystal with Strong Nonlinearity and a Wide Phase-Matching Region from π-Conjugated (HCNO) Groups.

Mixed-alkali-metal hydroisocyanurate nonlinear-optical crystal RbLi(HCNO)·2HO was grown by a facile aqueous solution method. It exhibits a short phase-matching wavelength (λ = 239 nm) and a strong second-harmonic-generation response ( = 2.1KDP) benefitting from the well-aligned planar π-conjugated (HCNO) anions, as confirmed by the first-principles calculations.

BaM(CNO) (M = Sr, Pb): Band Engineering from p-π Interaction via Homovalent Substitution in Metal Cyanurates Containing Planar π-Conjugated Groups.

The two new metal cyanurates BaM(CNO) (M = Sr, Pb) were successfully grown by a solid-state cyclotrimerization reaction. The electronic energy bands of BaM(CNO) are totally divergent in spite of their same structures and similar interlayer distances. Theoretical calculations show the narrowing band gap of BaPb(CNO) stems from the strong interaction between Pb 6p orbitals and anti-π orbitals in (CNO) groups.

Parallel Alignment of π-Conjugated Anions in Hydroisocyanurates Enhancing Optical Anisotropy.

Birefringent crystals with optical anisotropy, which are employed to modulate the polarization of light, play a vital role in many fields of the optical industry. In this Communication, two mixed alkali metal hydroisocyanurates, RbLi(HCNO)·2HO () and CsLi(HCNO)·2HO (), were synthesized by a simple aqueous solution method, and they feature layered structures composed of [HCNO] ribbons through hydrogen bonds with the separation of water molecules and alkali cations. They exhibit a simultaneously short ultraviolet cutoff and giant birefringence, resulting from the perfect parallel alignment of π-conjugated (HCNO) anions.

A rich structural chemistry in π-conjugated hydroisocyanurates: layered structures of AB(HCNO)·nHO (A = K, Rb, Cs; B = Mg, Ca; n = 4, 10) with high ultraviolet transparency and strong optical anisotropy.

Ultraviolet (UV) transparent birefringent crystals are indeed indispensable for modern optoelectronics and polarizer devices. Herein, mixed alkali/alkali-earth metal hydroisocyanurates A2B(H2C3N3O3)4·nH2O (A = K, Rb, Cs; B = Mg, Ca; n = 4, 10) were synthesized and their thermal, vibrational and optical properties were characterized in detail. Although they crystallize in different crystallographic point groups, all compounds feature quasi-two-dimensional layered structures built by the 2∞[H2C3N3O3]- ribbons through hydrogen bonds, separated by water molecules and cations.

Synthesis, Structure, and Characterization of Two Mixed-Cation Quaternary Chalcogenides KBaSnQ (Q = S, Se).

Two new isostructural metal chalcogenides, KBaSnS and KBaSnSe, have been isolated for the first time. They feature the intriguing ∞ 1[BaSnQ] (Q = S, Se) tunnel structures which are separated by K cations. Experiments combined with theoretical calculations demonstrate that KBaSnS possesses a large energy gap (3.

SnGaGeSe, a benign addition to the AMMQ family: synthesis, crystal structure and nonlinear optical performance.

A new selenide, SnGa2GeSe6, in the AMIII2MIVQ6 family was synthesized for the first time by a high-temperature solid-state reaction. It crystallized in the non-centrosymmetric space group Fdd2 with cell dimensions of a = 47.195(9) Å, b = 7.

Sr Cd Sb O S : Strong SHG Response Activated by Highly Polarizable Sb/O/S Groups.

A new nonlinear optical (NLO) oxysulfide, Sr Cd Sb O S , which contains the functional groups [SbO S ] (x=0, 1) with a 5s electron configuration, is synthesized by a solid-state reaction. This compound displays a phase-matchable second harmonic generation (SHG) response four times stronger than AgGaS (AGS) under laser irradiation at 2.09 μm.

NaCa(TeO)(PO): a new noncentrosymmetric tellurite phosphate with fascinating multimember-ring architectures and intriguing nonlinear optical performance.

A new functional compound Na3Ca4(TeO3)(PO4)3 has been successfully synthesized and fully characterized. It is the first example of a tellurite phosphate that exhibits a fascinating multimember-ring configuration. Moreover, a careful theoretical and experimental study also reveals the intriguing nonlinear optical performance of Na3Ca4(TeO3)(PO4)3.

NaBOF: a new sodium-rich fluorooxoborate with a unique [BOF] ring and a short ultraviolet absorption edge.

A new sodium-rich fluorooxoborate Na3B7O11F2 features a novel large [B14O24F4] ring formed by two corner-shared [B7O13F2] groups, each containing two [B3O7] anionic units linked by a [BO2F2] group. The band gap of the title compound calculated by using first-principles calculations is 7.69 eV (∼161 nm) and the birefringence refractive index is 0.

ZnPS: A Promising Infrared Nonlinear-Optical Material with Excellent Overall Properties.

The thiophosphate ZnPS is reported for its potential application in infrared (IR) nonlinear optics. This nondeliquescent compound features a cubic closet packing of the (PS) groups, with Zn filling in three-quarters of the tetrahedral interspaces. The optical band gap of ZnPS is characterized as 3.

KZnGeS: A Congruent-Melting Infrared Nonlinear-Optical Material with a Large Band Gap.

KZnGeS belonging to the noncentrosymmetric space group P2 of the monoclinic system was discovered via a solid-state method. It possesses two-dimensional [ZnGeS] layers, with alkali-metal cations K located between the layers. On the basis of UV-vis-near-IR diffuse-reflectance spectrometry, the band gap of KZnGeS is 3.

Synthesis, crystal structure and optical properties of a new fluorocarbonate with an interesting sandwich-like structure.

A new fluorocarbonate, Na3Zn2(CO3)3F, was synthesized using a subcritical hydrothermal method. Na3Zn2(CO3)3F crystallizes in the space group C2/c with a sandwich-like framework in which the stacked [Zn(CO3)]∞ layers are connected with one another by bridging F atoms and [CO3] groups alternately. Interestingly, each Zn atom is surrounded by one F atom and four O atoms, forming a distorted [ZnO4F] trigonal bipyramid, which is observed for the first time in the carbonate system.

Beryllium-Free Nonlinear-Optical Crystals ABaLiGaBOF (A = K and Rb): Members of the SrBe(BO)O Family with a Strong Covalent Connection between the [LiGaBOF] Double Layers.

Two gallium-based borates, KBaLiGaBOF (I) and RbBaLiGaBOF (II), have been successfully grown in the MO (M = K, Rb)-LiF-BO flux. They can be recognized as the element cosubstitutions of Sr for K/Rb and Ba and of Be for Li and Ga from SrBe(BO)O (SBBO), which uses poisonous beryllium oxide during the synthesis and crystal growth process and also exhibits the problem of structural instability. The isostructural borates crystallize into the noncentrosymmetric space group P6̅2 c, with a = 8.

K Li Gd (BO ) : A New Gadolinium-Rich Orthoborate for Cryogenic Magnetic Cooling.

Magnetic cooling technology based on magnetocaloric effect (MCE) has attracted great interest in obtaining extremely low temperatures, for example, for space exploration. Here, we grew a new gadolinium-rich orthoborate K Li Gd (BO ) (1) as a promising cryogenic magnetic coolant. It exhibits a complicated three dimensional framework constructed from BO groups and gadolinium-oxygen chains.

Noncentrosymmetric Cubic Cyanurate KCd(CNO) Containing Isolated Planar π-Conjugated (CNO) Groups.

Single crystals of KCd(CNO) (1) were successfully grown via a solid-state cyclotrimerization reaction method from CdCl and KOCN. To our best knowledge, it is the first inorganic compound containing isolated six-membered-ring (6-MR) anionic groups that crystallizes in the cubic system. In the structure, the basic 6-MR anionic unit is a planar π-conjugated (CNO) group that is isoelectronic with the (BO) group, as observed in the benchmark nonlinear-optical (NLO) crystal β-BaBO with strong second-harmonic-generation response.

Two KBBF-Type Beryllium Borates MBeBO (M = Sr, Ba) with a Three-Dimensional (BeBO) Network.

Two new polyborates, BaBeBO and SrBeBO, in a three-dimensional (BeBO) network featuring KBBF-type two-dimensional planes are synthesized. Compared with KBBF, both compounds possess comparable optical birefringence and deep-ultraviolet (deep-UV) cutoff edges and exhibit better bulk growth habits owing to their three-dimensional networks, which make them applicable deep-UV optical materials.

BaZn(BO): A Nonlinear-Optical Material with Reinforced Interlayer Connections and Large Second-Harmonic-Generation Response.

A nonlinear-optical crystal BaZn(BO) (BZBO) is obtained that is constructed with [Zn(BO)O] units bridged by planar BO groups along the a axis based on the flexibility of the BO and ZnO groups. The distance between adjacent [Zn(BO)O] layers in BZBO is 5.07 Å, which is much shorter than those of KBeBOF, BaZn(BO), and NaCsBeB5O.

Structural Design of Two Fluorine-Beryllium Borates BaMBe(BO)F (M = Mg, Ca) Containing Flexible Two-Dimensional [BeBOF] Single Layers without Structural Instability Problems.

Molecular structural design is a compelling strategy to develop new compounds and optimize the crystal structure by atomic-scale manipulation. Herein, two fluorine-beryllium borates, BaMgBe(BO)F and BaCaBe(BO)F, have been rationally designed to overcome the structural instability problems of SrBeBO (SBBO). When relatively large Ba atoms were introduced, the [BeBO] double layers of SBBO were successfully broken, generating flexible [BeBOF] single layers.

Homologous Series of 2D Chalcogenides Cs-Ag-Bi-Q (Q = S, Se) with Ion-Exchange Properties.

Four new layered chalcogenides CsAgBiS, CsAgBiSe, CsAgBiS, and CsAgBiSe are described. CsAgBiS and CsAgBiSe are isostructural and have a hexagonal P6/mmc space group; their structures consist of [Ag/Bi]Q (Q = S, Se) quintuple layers intercalated with disordered Cs cations. CsAgBiS also adopts a structure with the hexagonal P6/mmc space group and its structure has an [Ag/Bi]S layer intercalated with a Cs layer.

Orthoborates LiCdRE(BO) (RE = Sm-Lu and Y) with Rare-Earth Ions on a Triangular Lattice: Synthesis, Crystal Structure, and Optical and Magnetic Properties.

Single crystals of LiCdY(BO) were successfully grown from a LiO-BO flux, and its lanthanide homotypic compounds, LiCdRE(BO) (RE = Sm-Lu), have been prepared by solid-state reaction. They crystallize in the noncentrosymmetric space group P622 with cell parameters in the ranges of a = 7.0989(2)-6.

Pb@Pb Basket-like-Cluster-Based Lead Tellurate-Nitrate Kleinman-Forbidden Nonlinear-Optical Crystal: PbTeO(OH)(NO).

The first lead tellurate-nitrate nonlinear-optical (NLO) crystal, PbTeO(OH)(NO), featuring a 3D anionic diamondlike toplogical structural motif formulated as [PbO] constructed by unique nonanuclear basket-shaped Pb@PbO clusters has been hydrothermally achieved, in which the Pb@PbO cluster shows a core-shell structure with one PbO polyhedron enclosed by eight PbO (x = 3 and 4) polyhedera via edge and face sharing. The hexavalent Te in TeO(OH) octahedra is linked to a [PbO] cluster to form a rare [PbTeO(OH)] cationic framework. The compound demonstrates a powder second-harmonic-generation (SHG) response of about 1.

PbMnGaS and PbMnGaSe: Two Quaternary Metal Chalcognides with Open-Tunnel-Framework Structures Displaying Intense Second Harmonic Generation Responses and Interesting Magnetic Properties.

By combining different nonlinear optical-active structural chromophores with transition metal Mn into a crystal structure, two novel quaternary metal chalcogenides PbMnGaS (1) and PbMnGaSe (2) were successfully synthesized. Compounds 1 and 2 are isostructural, and they represent a new structure type that crystallizes in the space group P6̅ (No. 174) in the hexagonal system.

The Two-Dimensional ACdBiQ (A = K, Rb, Cs; Q = S, Se): Direct Bandgap Semiconductors and Ion-Exchange Materials.

We report the new layered chalcogenides ACdBiQ (A = Cs, Rb, K; Q = S and A = Cs; Q = Se). All compounds are isostructural crystallizing in the orthorhombic space group Cmcm, with a = 4.0216(8) Å, b = 6.