KBa3M2F14Cl (M = Zr, Hf): novel short-wavelength mixed metal halides with the largest second-harmonic generation responses contributed by mixed functional moieties.

The development of short-wavelength nonlinear optical (NLO) materials is indispensable and urgently required for further applications. Halides have been disregarded as potential NLO materials with deep-ultraviolet (DUV) cutoff edges due to their weak second-harmonic generation (SHG) response and poor birefringence. Here, two novel and isostructural halides, KBa3M2F14Cl (M = Zr (KBZFC), Hf (KBHFC)), possess structures that are formed by isolated MF7 monocapped triangular prisms and dissociative K+, Ba2+, and Cl- ions. Compared with reported metal halides that are transparent to the DUV region, KBZFC and KBHFC possess the strongest SHG responses (approximately 1, 0.9 × KH2PO4), which are contributed by the synergistic effect of MF7 (M = Zr, Hf) groups, Ba2+ cations, and Cl- ions. The zero-dimensional structures favour sufficient birefringences (0.12, 0.10 @ 1064 nm) for phase-matchable (PM) behaviours. The discovery of KBZFC and KBHFC showcases the potential of NLO mixed metal halides transparent to the DUV region.

From CaBaM2F12 to K2BaM2F12 (M = Zr, Hf): Heterovalent Cation-Substitution-Induced Symmetry Break and Nonlinear-Optical Activity.

Designing short-wavelength nonlinear-optical (NLO) crystals is of vital importance for laser applications. Here, the combination of alkaline-earth metals, d0 transition metals, and F atom has generated two new and isostructural fluorides, CaBaZr2F12 (CBZF) and CaBaHf2F12 (CBHF), which adopt centrosymmetric space group I4/mmm. Taking CBZF and CBHF as the parents, two new fluorides, K2BaZr2F12 (KBZF) and K2BaHf2F12 (KBHF), with an Imm2 polar structure were obtained via a heterovalent cation substitution strategy. All four compounds feature ZrF8-dodecahedra-built {[Zr2F12]4-}∞ chains and show short ultraviolet cutoff edges (<200 nm). KBZF and KBHF show phase-matchable behavior with moderate second-harmonic-generation responses [0.6 and 0.35 × KH2PO4 (KDP)] under 1064 nm laser radiation. This work enriches fluorides as promising short-wavelength NLO materials.

HgBr2: an easily growing wide-spectrum birefringent crystal.

Birefringent materials are of great significance to the development of modern optical technology; however, research on halide birefringent crystals with a wide transparent range remains limited. In this work, mercuric bromide (HgBr2) has been investigated for the first time as a promising birefringent material with a wide transparent window spanning from ultraviolet (UV) to far-infrared (far-IR) spectral regions (0.34-22.9 µm). HgBr2 has an exceptionally large birefringence (Δn, 0.235 @ 546 nm), which is 19.6 times that of commercial MgF2. The ordered linear motif [Br-Hg-Br] with high polarizability anisotropy within the molecule is the inherent source of excellent birefringence, making it an efficient building block for birefringent materials. In addition, HgBr2 can be easily grown under mild conditions and remain stable in air for prolonged periods. Studying the birefringent properties of HgBr2 crystals would provide new ideas for future exploration of wide-spectrum birefringent materials.

Pentanary Oxythiogermanates Ba3MGe3O2S8 (M = Ca, Zn) Featuring [Ge3O2S8]8- Trimers and {[MGe3O2S8]6-}∞ Chains: Structural Chemistry and Physical Properties.

Oxychalcogenides are increasingly attracting wide attention because they contain multiple anions that may combine the advantages of oxides and chalcogenides. In this work, two new pentanary oxythiogermanates, Ba3MGe3O2S8 [M = Ca (1), Zn (2)], were synthesized by a high-temperature solid-state reaction. They crystallize in the orthorhombic space group Pnma, and their structures contain isolated [Ge3O2S8]8- units constructed by one [GeO2S2] and two [GeOS3] tetrahedra that link with M2+ ions to build the {[MGe3O2S8]6-}∞ chain, representing a new type of oxythiogermanate. Notably, a [ZnS5] square pyramid exists in 2. Their structural chemistry and relationship with relevant structures are analyzed. 1 and 2 exhibit wide band gaps of 3.93 and 2.63 eV, birefringences of 0.100 and 0.089 at 2100 nm, respectively, and also obvious photocurrent responses. This work may be extended to a family of AE3MIIMIV3O2Q8 (AE = alkali-earth metal; MII = Ca, Zn, Cd, Hg; MIV = Si, Ge, Sn; Q = S, Se), and further systematic survey on them can be performed to enrich the study of multifunctional oxychalcogenides.

Design of Pentanary Mixed-Chalcogenides Ag2In2SiS6-xSex (x = 1, 2) Based on the Bucket Effect: Local Structural Difference and High-Performance Nonlinear-Optical Properties Realized by Partial Congener Substitution.

Noncentrosymmetric chalcogenides are promising candidates for infrared nonlinear-optical (NLO) crystals, and exploring high-performance ones is a hot topic and challengeable. Herein, the combination of AgQ4, InQ4, and SiQ4 (Q = S, Se) units with different S/Se ratios resulted in the discovery of the tetrahedral chalcogenides Ag2In2SiS4Se2 (1) and Ag2In2SiS5Se (2). They both crystallize in the monoclinic Cc space group with different local structures. Co-occupied S/Se sites only exist in 2, and the arrangement of [In2SiQ3] six-membered rings builds different helical chains and 3D [(In2SiQ6)2-]n polyanionic frameworks in 1 and 2. They show balanced NLO performances, including phase-matchable moderate NLO responses (0.7 and 0.5 × AGS) and enhanced laser-induced damage thresholds (4.5 and 5.1 × AGS). Theoretical calculations reveal that their NLO responses are predominantly contributed by the AgQ4 and InQ4 units.

Hg16O12(NO3)6F2(H2O): A Mercury-Rich Nitrate Oxyfluoride with Diverse Triple-Coordinated Mercury-Based Units That Exhibits an Unparalleled [(Hg16O12F2(H2O))6+]∞ Cationic Framework and a Large Birefringence.

Designing new compounds based on anion regulation has been widely favored due to the production of diverse crystal structures and excellent optical properties. Here, a new nitrate oxyfluoride, Hg16O12(NO3)6F2(H2O), has been obtained through a hydrothermal reaction. It crystallizes in the centric Ibca space group and shows a novel three-dimensional [(Hg16O12F2(H2O))6+]∞ cationic framework composed of interconnected HgO2F, HgO3, and HgO2(H2O) units, with isolated NO3- groups as balanced anions to build the whole structure. Notably, the HgO2F and HgO2(H2O) units are first presented here among mercury (Hg)-based compounds. Additionally, Hg16O12(NO3)6F2(H2O) exhibits a large birefringence of 0.17 at 546 nm. This work enriches the multiformity of Hg-based compounds and provides a route for developing promising birefringent materials.

Polysubstitution Induced Centrosymmetric-to-Noncentrosymmetric Structural Transformation and Nonlinear-Optical Behavior: The Case of Na0.45Ag0.55Ga3Se5.

Obtaining compounds with large nonlinear-optical (NLO) coefficients and wide band gaps is challenging due to their competitive requirements for chemical bonds. Herein, the first member with mixed cations on the A site in the A-M3-Q5 or A-Ag-M6-Q10 (A = alkali metal; M = Ga, In; Q = S, Se, Te) family, viz. Na0.45Ag0.55Ga3Se5 (NAGSe), was obtained by a solid-state reaction. Its structure features [GaSe4] tetrahedra built three-dimensional {[Ga3Se5]-}∞ network, with Na and Na/Ag cations located at the octahedral cavities. Noncentrosymmetric (R32) NAGSe can also be transformed from centrosymmetric RbGa3S5 (P21/c) via multiple-site cosubstitution. NAGSe exhibits the highest NLO response (1.9 × AGS) in the A-Ag-M-Q family. Crystal structure analysis and theoretical calculations suggest that the NLO response is mainly contributed by the regularly arranged [GaSe4] units. This work enriches the exploration of the undeveloped A-M3-Q5 or A-Ag-M6-Q10 family as potential infrared NLO materials.

Exploring a new short-wavelength nonlinear optical fluoride material featuring unprecedented polar cis-[Zr6F34]10- clusters.

Traditional fluorides are rarely reported as candidates for nonlinear optical (NLO) materials featuring a deep-ultraviolet cutoff edge. Theoretical investigations suggest that the ZrF8 dodecahedron shows large polarizability anisotropy and benefits for large birefringence. Herein, a new fluorine-rich fluoride, K3Ba2Zr6F31, was synthesized by coupling the ZrF8 group, featuring acentric cis-[Zr6F34]10- clusters with a 63-screw axis. Significantly, K3Ba2Zr6F31 exhibits a short UV cutoff edge (below 200 nm) and moderate second-harmonic generation (SHG) response (0.5 × KH2PO4). It also possesses a relatively large birefringence (0.08@1064 nm), together with a broad transparency window (2.5-21.1 µm). First-principles calculations suggest that the cis-[Zr6F34]10- cluster built by ZrF8 dodecahedra are the dominant contributors to the large band gap (7.89 eV, cal.) and SHG response simultaneously. Such systematic work highlights that Zr-based fluorides afford a new paradigm for the development of efficient NLO materials with a short UV cutoff edge.

KREP2S6 (RE = Sm, Gd, Tb, Dy): A Series of Polar Rare-Earth Thiophosphates with High Laser-Induced Damage Thresholds and Moderate Nonlinear-Optical Responses Synergistically Contributed by Isolated P2S6 Units and {[RE2S15]24-}∞ Layers.

As one of the potential candidates of nonlinear-optical (NLO) materials, rare-earth chalcophosphates have demonstrated promising properties. Here, KREP2S6 (RE = Sm, Gd, Tb, Dy) were synthesized using the facile RE2O3-B-S solid-state method. They crystallize with a monoclinic chiral P21 structure, and their layer structures are built by isolated ethane-like P2S6 dimers and RES8 bicapped trigonal prisms built {[RE2S15]24-}∞ layers. By comparing the structures with related ones, the change of the alkali metal or RE3+ ions can cause structural transformation. Their band gaps are tunable between 2.58 and 3.79 eV, and their powder samples exhibit good NLO properties. Theoretical calculations suggest that the NLO properties are mainly contributed by P2S6 units and {[RE2S15]24-}∞ layers synergistically, in which {[RE2S15]24-}∞ layers and P2S6 units dominate the contribution to the band gap and second-harmonic-generation response, respectively. This work enriches the application of rare-earth chalcophosphates as NLO materials.

NaREP2Se6 (RE = Y, Sm, Gd-Dy): Quaternary Rare-Earth Selenophosphates with Unique 3D {[REP2Se6]-}∞ Framework Built by RESe8 and P2Se6 Motifs and Multiple Properties.

Rare-earth (RE) chalcophosphates have been widely studied because of their abundant structures. Here, five new RE selenophosphates, NaREP2Se6 (RE = Y, Sm, Gd-Dy), were synthesized by a facile RE oxide-boron-selenium solid-state route. They crystallize in the triclinic P1̅ space group, featuring three-dimensional (3D) structures constructed by RESe8 and P2Se6 motifs, different from common 2D RE chalcophosphates A-RE-P2-Q6 (A = alkali metal; Q = S, Se) system. Their structural chemistry and relationship with related phases are analyzed. Both the size of A and the coordination geometry of RE have important influences on the system's structures. Their optical band gaps are tunable from 1.79 to 2.50 eV, and they exhibit diverse magnetic behaviors, including Van-Vleck-type paramagnetism, antiferromagnetism, and ferromagnetism. Their photocurrent responses and thermal stabilities are analyzed as well. Calculation results suggest that the RESe8 and P2Se6 units make a great contribution to the optical properties. This work enriches the chemistry and multifunctional properties of RE chalcophosphates.

Eu2MGe2OS6 (M = Mn, Fe, Co): Three Melilite-Type Rare-Earth Oxythiogermanates Exhibiting Balanced Nonlinear-Optical Behaviors.

Metal oxychalcogenides as candidates for novel mid-infrared nonlinear-optical materials have attracted great interest due to the distinctive advantages of oxides and chalcogenides in this field. Herein, the first melilite-type rare-earth (RE) oxythiogermanates Eu2MGe2OS6 [M = Mn (1), Fe (2), Co (3)] are obtained by combining RE metals with localized f electrons, magnetic transition metals with delocalized d electrons, and the highly distorted mixed anionic group [GeOS3] into one structure. They belong to the tetragonal P4̅21m space group, and highly distorted [EuOS7] bicapped trigonal prisms bridge adjacent {[MGe2OS6]4-}∞ layers to build the three-dimensional network. Their optical band gaps are determined as 2.40, 2.11 and 2.14 eV, and they show moderate second-harmonic-generation (SHG) responses (0.3, 0.3 and 0.5 × AGS) and large laser-induced damage thresholds (2.77-8.31 × AGS). Theoretical calculation results indicate that the synergistic effect of [EuOS7] and [MS4] units acts on the SHG effect. This work enriches the crystal chemistry of melilite-structure materials.

Hydroxysafflor yellow A inhibits the hyperactivation of rat platelets by regulating the miR-9a-5p/SRC axis.

Pathological platelet activation plays a vital role in the prevalence of cardiovascular diseases. Hydroxysafflor yellow A (HSYA) has been shown to have significant anti-platelet aggregation and anti-activation effects, but its mechanism of action is unclear. Our study showed that HSYA inhibited the expression of platelet surface glycoproteins IIß/III α (GPIIß/III α) and thromboxane A2 (TXA2) during platelet activation and reduced platelet Ca2+ accumulation. HSYA significantly reduced the number of platelets and inhibited adrenaline-induced platelet hyperaggregation in rats. Transcriptomic analysis of platelets suggested that HSYA significantly suppressed SRC and MAPK3 (ERK1/2) gene expression. YEEI peptide, an SRC activator, could significantly reverse the inhibition of HSYA on the phosphorylation of SRC/PLCγ2/PKCδ/MEK/ERK1/2 pathway proteins and reverse the effect of HSYA on platelet activation-related markers GPIIß/IIIα protein, TXA2 and cAMP. The SRC genes were further predicted by transcriptome analysis of HSYA-regulated miRNAs combined with bioinformatics techniques. The results suggested that HSYA could significantly upregulate the expression level of the miR-9a-5p gene and further confirmed that miR-9a-5p had a targeted regulatory relationship with SRC by dual-luciferase activity reporter and cell transfection experiments. The inhibitory effect of HSYA on the SRC/PLCγ2/PKCδ/MEK/ERK1/2 pathway was significantly reversed after platelets were transfected with the miR-9a inhibitor, while SRC siRNA attenuated the effect of the miR-9a inhibitor. SRC siRNA was able to attenuate the effect of the miR-9a inhibitor. In conclusion, this study suggests that HSYA can inhibit the activation of the SRC/PLCγ2/PKC δ/MEK/ERK1/2 axis by upregulating platelet miR-9a-5p, thereby reducing the activation of platelets and inhibiting platelet aggregation.

Three-in-One Tetrahedral Functional Units Constructing Diamondlike Ag2In2SiS3.06Se2.94 with High-Performance Nonlinear-Optical Activity.

Exploration of new functional materials with enhanced performance from known ones is always an attractive strategy. A new infrared (IR) nonlinear-optical (NLO) mixed chalcogenide Ag2In2SiS3.06Se2.94 (1), was obtained through partial congener substitution originated from Ag2In2SiS6 (0). 1 crystallizes in the monoclinic space group Cc, and its three-dimensional (3D) polyanionic network is composed of {[In4Si2Se5(S/Se)11]12-}∞ helical chains sharing S/Se(5) corner atoms with cavities embedded with counterion Ag+ ions. It exhibits a much enhanced NLO response compared to that of 0, reaching 1.1 × AgGaS2. Further theoretical analysis results indicate that the large NLO response can be attributed to the synergistic effect of AgQ4 and InQ4 tetrahedral functional motifs. This work not only reports a new high-performance IR NLO material but also enriches the partial ion substitution strategy to obtain new functional materials.

KHg4Ga3S9: A Hg-Based Sulfide with Nonlinear-Optical Activity in the A-MII-MIII-Q (A = Alkali Metal; MII = d10 Metal; MIII = Ga, In; Q = S, Se) System.

The search for new high-performance infrared (IR) nonlinear-optical (NLO) materials is a hot topic in the fields of laser chemistry and inorganic solid-state chemistry. Here, a new Hg-based sulfide KHg4Ga3S9 in the family of A-MII-MIII-Q (A = alkali metal; MII = d10 metal; MIII = Ga, In; Q = S, Se) was synthesized. It crystallizes in the orthogonal system of the C2221 structure, which is rare for IR NLO chalcogenides. Its anionic framework {[Hg4Ga3S9]-}∞ is constructed by two types of interconnected helical chains, viz., the inner layer ({[Hg6Ga2S29/3]4/3-}∞) and the outer layer ({[Hg2Ga4S25/3]2/3-}∞). It exhibits a moderate NLO response and a high laser-induced damage threshold. Theoretical calculations indicate that the HgS4 unit accounts for its much larger NLO response compared to RbCd4Ga3S9. The influence of alkali metals and d10 metals on the initial phase-matching wavelength is also discussed. This work provides inspiration for improving the properties of NLO materials' properties.

Dual Monomeric Inorganic Units Constructed Bright Emissive Zero-Dimensional Antimony Chlorides with Solvent-Induced Reversible Structural Transition.

A5M2X11 and A3M2X9 families (A = monovalent organic cation; M = trivalent metal; X = halogen) are receiving increasing attention because of their combination of easy solution processability and superior ferroelectricity properties. However, synthesizing highly efficient A5M2X11 and A3M2X9-type fluorophores with multiple monomeric inorganic units and achieving their structural interconversion remains challenging. Here, we report two novel zero-dimensional (0D) antimony halides, (C10H16N)5Sb2Cl11·C2H3N (1) and (C10H16N)3Sb2Cl9 (2), which not only contain two distinct [SbXn]3-n units but also have excellent orange (590 nm) and yellow-green emission (540 nm) with high PLQY of 17.7% and 31.5%, respectively. Interestingly, a reversible structural conversion could be triggered by acetonitrile steam stimulation, accompanied by luminescence switching properties. This work not only enriches the structure of hybrid Sb-based halides but also provides the possibility of well-known A5M2X11 and A3M2X9 families as structural transformation materials.

Mixed Rare-Earth Chalcogenide Borate Eu9-xRExMgS2B20O41 (RE = Sm, Gd) Featuring a 3D {[B20O41]22-}∞ Framework Connected by [B6O9(O0.5)6]6- and [B7O13(O0.5)3]8- Clusters.

Rare-earth (RE) chalcogenide borates are very rarely discovered in view of the difficulties in synthesis though they have demonstrated attractive physical performances. Here, the first mixed RE chalcogenide borates Eu5.4Sm3.6MgS2B20O41 (1) and Eu3Gd6MgS2B20O41 (2) are synthesized by combining RE, sulfur, and borate ions into one structure. They crystallize in the centrosymmetric hexagonal space group P63/m, and their 3D honeycomb-like {[B20O41]22-}∞ open frameworks are built by [B6O9(O0.5)6]6- and [B7O13(O0.5)3]8- polyanionic clusters and consolidated by Mg2+ ions; both of which are formed by BO4 tetrahedra and BO3 planar triangles. The coordination modes of RE ions are rare REO6S2 bicapped trigonal prisms and REO8S irregular polyhedra, and their band gaps are determined to be 2.25 and 2.22 eV, respectively. They exhibit antiferromagnetic interactions and distinct photocurrent responses. The corresponding theoretical calculations are also performed. The study of 1 and 2 perhaps stimulates interest in exploring new functional RE chalcogenide borates.

Three-in-One Strategy Constructing the First High-Performance Nonlinear Optical Sulfide Crystallizing with the P43 Space Group.

The balance between large nonlinear optical (NLO) effect and wide bandgap is the key scientific issue for the exploration of infrared NLO materials. Targeting this issue, two new pentanary chalcogenides KGaGe1.37 Sn0.63 S6 (1) and KGaGe1.37 Sn0.63 Se6 (2) are obtained by the three-in-one strategy, viz. three types of fourfold-coordinated metal elements co-occupying the same site. They crystallize in the tetragonal P43 (1) and monoclinic Cc (2) space group. Their structures can be evolved from benchmark AgGaS2 (AGS) by suitable substitution. Remarkably, 1 is the first NLO sulfide crystallizing with the P43 space group, representing a new structure-type NLO material. The structural relationship between 1 and 2 and the evolution from 1, 2 to AGS are also analyzed. Both 1 and 2 show balanced NLO properties. Specifically, 1 exhibits phase-matchable SHG response of 0.6 × AGS, a wide bandgap of 3.50 eV, and a high laser damage threshold of 6.24 × AGS. Theoretical calculation results suggest that the Ga/Ge/Sn element ratios of the co-occupied sites of 1 and 2 are the most appropriate for stabilizing the structures. The strategy adopted here will provide some inspiration for exploring new high-performance NLO materials.

Study on the Controllable Preparation of Nd3+ Doped in Fe3O4 Nanoparticles for Magnetic Protective Fabrics.

Magnetic protective fabrics with fine wearability and great protective properties are highly desirable for aerospace, national defense, and wearable protective applications. The study of the controllable preparation method of Nd3+ doped in Fe3O4 nanoparticles with supposed magnetic properties remains a challenge. The characterization of the microstructure, elemental composition, and magnetic properties of NdFe2O4 nanoparticles was verified. Then, the surface of NdFe2O4 was treated with glyceric acid to provide sufficient -OH. Subsequently, the connection of the nanoparticle by the succinimide group was studied and then grafted onto cotton fabrics as its bridging effect. The optimal loading rate of the functional fabrics with nanoparticles of an average size of 230 nm was 1.37% after a 25% alkali pretreatment. The color fatness to rubbing results showed better stability after washing and drying. The corresponding hysteresis loop indicated that the functional fabrics exhibited typical magnetism behavior with a closed "S" shape and a magnetic saturation value of 17.61 emu.g-1 with a particle size of 230 nm. However, the magnetic saturation value of the cotton fabric of 90 nm was just 4.89 emu.g-1, exhibiting controllable preparation for the aimed electromagnetic properties and great potential in radiation protective fields. The electrochemical properties of the functional fabrics exhibited extremely weak electrical conductivity caused by the movement of the magnetic dipole derived from the NdFe2O4 nanoparticles.

Multi-Stimuli Responsive Luminescence and Domino Phase Transition of Hybrid Copper Halides with Nonlinear Optical Switching Behavior.

Although phase transition materials (PTMs) under external stimuli are of great research interest duo to their rich potential applications, it is still challenging to explore multi-responsive PTMs. Herein, two different phases of organic-inorganic hybrid copper-based halides, α- and ß-Gua3 Cu2 I5 (Gua+ =CN3 H6 + ), were synthesized by solvent evaporation method, which they crystalize in the noncentrosymmetric space group Fdd2 with zero-dimensional structure and centrosymmetric space group C2/c with one-dimensional metal-halogen framework, respectively. Interestingly, it is firstly demonstrated that Gua3 Cu2 I5 simultaneously possesses reversible PL conversion and NLO switching properties in response to thermal stimulus. Strikingly, apart from heat, its structural phase transition can also be triggered by crystalline-phase-recognition (CPR) and mechanical force. These new findings may pave a path for future exploration of PTMs with multiple physical properties.

The first quaternary rare-earth oxythiogermanate with second-harmonic generation and ferromagnetic behavior.

The discovery of new functional materials is attractive since they have the opportunity to change some important fields. Of these materials, oxychalcogenides constitute an increasing type of nonlinear optical (NLO) material. Herein, a new rare-earth oxythiogermanate Eu3GeOS4 crystallizing with a polar orthorhombic Pca21 structure is studied. Its three-dimensional structure is constructed from unique [EuOS6] monocapped trigonal prisms and isolated [GeOS3] tetrahedra, featuring a new type of oxysulfides. Its band gap is 2.05 eV, and it exhibits obvious second-harmonic generation (SHG) response and high laser-induced damage threshold. In addition, Eu3GeOS4 exhibits Curie-Weiss ferromagnetic behavior in the high-temperature region. The SHG effect is ascribed to the synergistic effect of [EuOS6] and [GeOS3] units based on theoretical calculation results. This work is the first investigation of quaternary rare-earth oxythiogermanates as NLO materials.