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Inorganic metal chalcohalides, as significant semiconductor materials, have emerged as promising candidates for photoelectric applications. Herein, a new type of quaternary chalcohalide, [Ba4X][In19S32] (X = Cl, Br), has been discovered using the high-temperature halide salt flux method. Single-crystal X-ray diffraction analysis reveals that they are isostructural and crystallize in the tetragonal space group I41/amd (no. 141) featuring the octahedral hole formed by six [InS4]5− tetrahedra filled with a [ClBa4]7+ polycation, surrounded by a three-dimensional covalent framework formed by interconnecting [InS6]9− octahedra through corner-sharing and edge-sharing. Moreover, [Ba4Cl][In19S32] and [Ba4Br][In19S32] exhibit wide optical bandgaps of 2.70 eV and 2.46 eV, respectively, and moderate birefringences (0.044 @ 2100 nm and 0.042 @ 2100 nm, respectively). Specifically, [Ba4X][In19S32] (X = Cl, Br) display remarkable photocurrent responses under simulated solar-light illumination, implying their potential for photocatalytic applications. Theoretical calculations were employed to understand the interrelationship between the optical properties and electronic structure. The study on the synthesis and structure–property relationship analysis of inorganic metal chalcohalides provides new insight into the exploration of promising photoelectric materials. [ABSTRACT FROM AUTHOR]

Stability is a key factor that restricts the practical applications of metal–organic framework (MOF) materials. In this work, we report an ultrastable three-dimensional cage-like MOF, SrCu(HC3N3O3)2, constructed by a polydentate cyanurate ligand and two kinds of different metal nodes. A high ratio of coordination sites in organic ligands, specific coordination of strong acid with a strong base and weak acid with a weak base and double independent completed coordination networks endow SrCu(HC3N3O3)2 with outstanding thermal stability (up to 300 °C) and acid/alkali resistance (pH = 2–14). Moreover, SrCu(HC3N3O3)2 possesses the highest porosity up to 36.7% among cyanuric acid-based MOF materials and exhibits differentiated adsorption of C3H4 (63 cm3 g−1) and C3H6 (51 cm3 g−1). The breakthrough experiment further verified that efficient C3H4/C3H6 separation can be achieved under dynamic conditions by SrCu(HC3N3O3)2. [ABSTRACT FROM AUTHOR]

Metal thiophosphates have outstanding properties for the generation of mid-infrared coherent light and are an emerging nonlinear optical material system. In this study, a new non-centrosymmetric (NCS) quaternary alkaline-earth metal thiophosphate, SrAgPS4, was obtained via a high-temperature solid-state method. The new compound crystallizes in the NCS Ama2 (No. 40) space group and features two-dimensional [AgPS4]2− layers consisting of alternately connected [PS4] and [AgS4] tetrahedra. SrAgPS4 exhibits a strong phase-matched second harmonic generation response (1.10 × AgGaS2 at 2100 nm) and a large band gap (2.97 eV). In addition, theoretical calculations reveal the intrinsic relationship between the electronic structure and optical properties. This work enriches and greatly promotes the research on infrared nonlinear optical materials based on thiophosphates. [ABSTRACT FROM AUTHOR]

Inorganic metal chalcohalides are significant semiconductive materials for photovoltaics, photodetetion and infrared optics. Thus it is considerably rewarding to develop a new synthetic strategy to provide more degrees of freedom for atomic coordination to tune the optical and electronic properties of metal chalcohalides. In this work, the mixed-anion strategy is performed to synthesize two new metal chalcohalides Cs2InPS4X2 (X = Cl, Br) with mixed-anion structure by the reaction of InPS4 and CsX. Single-crystal X-ray diffraction analysis shows that they are isostructural and crystallize in the centrosymmetric space group P21/n, consisting of zero-dimensional structure [In2P2S8X4]4− (X = Cl, Br) built from tetrahedral [PS4]3− and octahedral [InS4X2]7− (X = Cl, Br) through edge-sharing, with Cs cations filling in intervening voids. The UV-vis-NIR diffuse reflectance spectroscopy measurement reveals that Cs2InPS4Cl2 and Cs2InPS4Br2 exhibit large optical bandgaps of 3.21 eV and 3.12 eV, respectively. The electronic structure calculations show that the bandgap mainly originates from the [InS4X2]7− (X = Cl, Br) mixed-anion groups. First-principles calculations indicate that the birefringence of Cs2InPS4Cl2 and Cs2InPS4Br2 is ∼0.08 and ∼0.05 at 2090 nm, respectively. Furthermore, thermal analysis reveals that the Cs2InPS4X2 (X = Cl, Br) are thermostable up to 400 °C. This discovery enriches the structural diversity of inorganic chalcohalides and provides an insight for the exploration of new semiconductive materials. [ABSTRACT FROM AUTHOR]

A new quaternary chalcogenide Ba4HgAs2S10 has been successfully synthesized with the aid of a KI flux. The compound crystallizes in the space group C2/c (no. 9) of the monoclinic system [a = 22.7787(6) Å, b = 6.4712(2) Å, c = 25.0606(7) Å, β = 90.101(2)° and Z = 8]. It is the first example of tetrahedral [AsS4]3− and linear [HgS2]2− units coexisting in a single compound. The [AsS4]3− tetrahedra and [HgS2]2− units are totally separated by Ba2+. The UV-visible diffuse reflectance spectrum reveals a large bandgap of 2.98 eV for Ba4HgAs2S10 and DSC measurement demonstrates the incongruent melting nature of the compound. Moreover, based on first-principles calculations, Ba4HgAs2S10 is a direct bandgap semiconductor with the optical property related to the electron transition from the S-3p orbital to As-4p and Ba-5d orbitals. [ABSTRACT FROM AUTHOR]

Two new rare-earth-based chalcogenides EuCdGeQ4 (Q = S, Se) have been designed and constructed by using Eu2+ and the classical NLO-active SBUs of [CdQ4] and [GeQ4]. They crystallize in a non-centrosymmetric Ama2 (no. 40) space group. Benefiting from the synergistic effects of [GeQ4] and highly distorted [CdQ4] tetrahedra, both compounds possess type-I phase-matching behaviour and large powder second harmonic generation (SHG) effects at 2.09 μm (2.6 and 3.8 × AgGaS2 for sulfide and selenide), as well as large direct band gaps (2.5 eV and 2.25 eV). Besides, they melt congruently at relatively low temperatures (997 °C for EuCdGeS4 and 882 °C for EuCdGSe4), which is suitable for bulk crystal growth by the Bridgman method. In addition, their electronic structures and some optical coefficients are calculated by first-principles. [ABSTRACT FROM AUTHOR]

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, Ba2(C3N3O3)(CNO) (I), containing two types of π-conjugated groups, planar (C3N3O3)3− six-membered rings and linear (CNO)− units, for the first time. The compound I exhibits the wide bandgap of 4.82 eV and high absorption coefficients in the wavelength range of 200–280 nm; this indicates that it is a potential optical detection material in the solar-blind region. [ABSTRACT FROM AUTHOR]

Two new quaternary selenides, namely Ba4Ga4SnSe12 and Ba6Ga2SnSe11, have been synthesized for the first time, representing the first two members in the A/M/Sn/Q (A = alkaline-earth metal; M = Al, Ga, In; Q = S, Se, Te) system. Ba4Ga4SnSe12 crystallizes in the non-centrosymmetric space group P4̅21/c of the tetragonal system and has a three-dimensional structure. Its three-dimensional framework is built up from corner-sharing GaSe4 and SnSe4 tetrahedra with eight-coordinated Ba2+ cations residing in the cavities. Ba6Ga2SnSe11 crystallizes in a new structure type in the monoclinic centrosymmetric space group P21/c. The structure of Ba6Ga2SnSe11 features a zero-dimensional structure containing totally isolated distorted SnSe4 tetrahedra and a discrete Ga2Se7 unit with Ba2+ cations located between them. On the basis of the diffuse-reflectance spectra, the band gaps are 2.16 (2) eV and 1.99 (2) eV for Ba4Ga4SnSe12 and Ba6Ga2SnSe11 respectively. In addition, the electronic structure calculation of Ba4Ga4SnSe12 indicates that it is a direct-gap semiconductor with the band gap mainly determined by the [Ga4SnSe12]8− anionic framework. [ABSTRACT FROM AUTHOR]

Two new quaternary selenides, namely Ba4Ga4SnSe12 and Ba6Ga2SnSe11, have been synthesized for the first time, representing the first two members in the A/M/Sn/Q (A = alkaline-earth metal; M = Al, Ga, In; Q = S, Se, Te) system. Ba4Ga4SnSe12 crystallizes in the non-centrosymmetric space group P4̅21/c of the tetragonal system and has a three-dimensional structure. Its three-dimensional framework is built up from corner-sharing GaSe4 and SnSe4 tetrahedra with eight-coordinated Ba2+ cations residing in the cavities. Ba6Ga2SnSe11 crystallizes in a new structure type in the monoclinic centrosymmetric space group P21/c. The structure of Ba6Ga2SnSe11 features a zero-dimensional structure containing totally isolated distorted SnSe4 tetrahedra and a discrete Ga2Se7 unit with Ba2+ cations located between them. On the basis of the diffuse-reflectance spectra, the band gaps are 2.16 (2) eV and 1.99 (2) eV for Ba4Ga4SnSe12 and Ba6Ga2SnSe11 respectively. In addition, the electronic structure calculation of Ba4Ga4SnSe12 indicates that it is a direct-gap semiconductor with the band gap mainly determined by the [Ga4SnSe12]8− anionic framework. [ABSTRACT FROM AUTHOR]