Layered Perovskite-like Nitrate Cs₂Pb(NO₃)₂Br₂ as a Multifunctional Optical Material

A novel alkali metal lead halide nitrate, Cs2Pb­(NO3)2Br2, has been successfully synthesized via a hydrothermal method. Interestingly, the title compound features a distinctive Ruddlesden–Popper perovskite-like layered structure, which induces the outstanding multifunctional optical properties, including a large birefringence (0.147@546 nm) and broad light-orange emission. Detailed structural analysis and theoretical calculations revealed that the large birefringence originates from the p−π interaction between the Pb2+ cations and NO3 groups and that the excellent luminescence properties derive from the distortion of PbO4Br4 polyhedra. This work not only enriches the variant structure types of layered perovskites but also guides the further exploration of all-inorganic multifunctional optical materials

SbHPO₃F: 2D van der Waals Layered Phosphite Exhibiting Large Birefringence

A novel antimony(III)-based phosphite, SbHPO3F, featuring a unique two-dimensional (2D) van der Waals layered structure, has been successfully designed and synthesized via the simultaneous employment of optically active moieties including SbO3F seesaw and tetrahedral HPO3 groups. Its optimized layered arrangement formed by the alternating connection of 4-membered rings (4-MRs) and 8-MRs endows the title compound with desirable optical properties including a large birefringence and short ultraviolet (UV) cutoff edge, implying that it is a potential UV birefringent material

Enhanced Second-Harmonic-Generation Response in a KH₂PO₄‑Type Calcium Nitrate Carboxylate with Unusual Three-Dimensional Inorganic and Organic Connections

An organic carboxylate ligand was employed in the synthesis of a nonhygroscopic nitrate-based nonlinear-optical (NLO) material. The hybrid-framework solid has unusual three-dimensional inorganic and organic connections with high thermal stability. Sharing similar structural features with the well-known NLO material KH2PO4 (KDP), this compound shows an enhanced second-harmonic-generation (SHG) response of about 1.6 times that of KDP. Theoretical calculations were carried out to reveal the origin of its SHG response

Two Mixed-Alkali-Metal Selenates as Short-Wave Ultraviolet Nonlinear-Optical Materials

Two novel mixed-alkali-metal selenate nonlinear-optical (NLO) crystals, Na3Li(H2O)3(SeO4)2·3H2O (I) and CsLi3(H2O)(SeO4)2 (II), have been successfully synthesized by an aqueous solution evaporation method. Both compounds feature the unique layers constructed of the same functional moieties including SeO4 and LiO4 tetrahedra: [Li(H2O)3(SeO4)2·3H2O]∞3– layers in I and [Li3(H2O)(SeO4)2]∞– layers in II. The titled compounds display wide optical band gaps of 5.62 and 5.66 eV, respectively, according to the UV–vis spectra. Interestingly, they exhibit significantly different second-order nonlinear coefficients (0.34 × KDP and 0.70 × KDP, respectively). Detailed dipole moment calculations manifest that the large disparity can be attributed to the difference in the dipole moment of the crystallographically independent SeO4 and LiO4 groups. This work confirms that alkali-metal selenate system is an excellent candidate for short-wave ultraviolet NLO materials

C(NH₂)₃MoO₃(IO₃): A Molybdenyl Iodate with Giant Birefringence Designed via a Cation–Anion Synergetic Interaction Strategy

Birefringent crystals are extensively utilized across diverse optical applications due to their unique property of splitting incident light into dual refracted rays, thereby modulating and controlling light polarization. The pursuit of promoting the birefringence of such crystals to facilitate device miniaturization has recently emerged as a prominent area of focus. In this investigation, we introduce two molybdenyl iodates, namely, C(NH2)3MoO3(IO3) and Rb2MoO2(I2O6)(IO3)2, conceived through a “cation–anion synergetic interaction” strategy. Each compound exhibits a one-dimensional chain structure. Despite processing similar wide band gaps (3.33 and 3.22 eV), these materials display a variance in their birefringence (Δn = 0.426 and 0.261 @546 nm). Notably, C(NH2)3MoO3(IO3) showcases the highest birefringence among all hitherto reported molybdenyl iodates, signifying its potential as a high-performance birefringent crystal. Theoretical analyses indicate that the C(NH2)3+ cation, acting as a birefringence-active unit, significantly bolsters the birefringence of molybdate iodates. Moreover, the presence of extensive hydrogen-bonding interactions between C(NH2)3+ cations and iodates influences the orientation of the highly anisotropic iodates, thereby further enhancing the birefringence of C(NH2)3MoO3(IO3). This research paves the way for the future exploration of organic–inorganic hybrid molybdenyl iodates exhibiting exceptional optical performance

Two Short-Wave UV Antimony(III) Sulfates Exhibiting Large Birefringence

In the present work, we have successfully obtained two new UV antimony-based sulfates, NH4Sb­(SO4)2 and Ca2Sb2O­(SO4)4, by a conventional hydrothermal method. Interestingly, both compounds share similar structural building blocks, such as SbO4 seesaws and SO4 tetrahedra, yet they endow discrepant birefringence values measured at 546 nm with values of 0.150 and 0.114, respectively, owing to the different distortions of the SbO4 groups with SCALP electrons. Moreover, both compounds display large band gaps (4.32 and 4.43 eV, respectively), so they can be used as short-wavelength UV birefringent materials. Moreover, NH4Sb­(SO4)2 is a noncentrosymmetric compound, showing a frequency doubling effect of 0.2 × KDP. Detailed structural analyses and calculations confirm the source of superior optical performance and the reasons for the different birefringence of the two compounds. This work provides ideas for the following discovery of antimony-based optical materials with excellent properties

Corrugated 1D Hybrid Metal Halide [C₆H₇ClN]CdCl₃ Exhibiting Broadband White-Light Emission

Organic–inorganic hybrid metal halides (OIMHs) exhibiting white-light emission are a splendid class of emitters and are regarded as desired phosphors for solid-state lighting applications. Here we report a single-component white-light-emitting hybrid metal halide, namely, [C6H7ClN]­CdCl3 (C6H7ClN = 4-(chloromethyl)­pyridinium), which features a corrugated 1D anionic double chain composed of edge-shared CdCl6 octahedrons and exhibits broadband white-light emission with a photoluminescence quantum yield of 12.3% under 365 nm UV light irradiation. Density functional theory calculations and temperature-dependent emission spectral analysis unveil that the broadband emission of [C6H7ClN]­CdCl3 is ascribed to self-trapped excitons. Moreover, a single-component white-light-emitting diode device with a correlated color temperature of 5214 K and color rendering index of 83.7 can be fabricated via coating [C6H7ClN]­CdCl3 on a 365 nm UV light-emitting diode chip. Such a promising luminescent material provides guidance for the design and synthesis of OIMHs with unique structures and desired properties

Homochiral Hybrid Organic–Inorganic Cadmium Chlorides Directed by Enantiopure Amino Acids

Homochiral cadmium chlorides were prepared under mild conditions using enantiopure amino acids as structure-directing agents. They feature a lacunary hexagonal CdCl2 lattice as well as a one-dimensional perovskite structure. The coexistence of protonated and zwitterionic amino acids between cadmium chloride chains is quite rare. These compounds are nonlinear optically active solids showing a moderate second-harmonic-generation response. Theoretical calculations were performed to reveal the origin of their nonlinear-optical properties

Two van der Waals Layered Antimony(III) Phosphites as UV Optical Materials

Herein, two new Sb3+-based phosphites, Sb2O2(HPO3) (I) and Sb2O­(HPO3)2 (II), were successfully obtained by ingeniously combining Sb3+-based polyhedra containing stereochemically active lone pair (SCALP) and HPO3 polar groups. Both reported compounds exhibit unique 2D van der Waals layered structures, [Sb4O4(HPO3)2]∞ and [Sb2O­(HPO3)2]∞, respectively, which favors compounds with large optical anisotropy. Interestingly, the different curvatures of the two layers resulted in the two title compounds showing significantly different birefringences (0.079@546 and 0.046@546 nm, respectively). Both compounds endow wide optical band gaps (4.32 and 4.54 eV, respectively), which indicates their potential as promising ultraviolet (UV) birefringent crystals. The synthesis of the two title compounds enriched Sb3+-based phosphites in the UV region and provided guidance for the subsequent synthesis of superior optical materials

Hg₃(SeO₃)₂(SO₄): A UV Nonlinear Optical Mercury Selenite Sulfate Constructed by Neat [Hg₆O₈(SeO₃)₄]_∞ Layers and SO₄ Tetrahedra

A novel mercury selenite sulfate named Hg3(SeO3)2(SO4) has been successfully synthesized under a mild hydrothermal method. Hg3(SeO3)2(SO4) crystallizes in a monoclinic space group P21 and features a unique three-dimensional (3D) frame structure formed by [Hg6O8(SeO3)4]∞ layers and SO4 tetrahedra, which enables it to exhibit a comprehensive performance of a moderate second-harmonic generation (SHG) response of approximately 1.3 times that of baseline KH2PO4 (KDP), a moderate birefringence (0.118@546 nm), and a wide band gap (4.70 eV), which indicates that it has potential for application as an ultraviolet (UV) nonlinear optical material. Detailed theoretical calculations show that the Hg2+-based polyhedra with large polarizability and deformability and the SeO3 groups with stereochemically active lone pair (SCALP) electrons are the main contributors to moderate optical properties