Search

Light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs) have brought about a revolution in lighting and display. A very hot field in recent years has been to develop white-light phosphors, aiming to achieve better colour stability, better reproducibility, and a simpler fabrication process for LEDs and OLEDs. This feature article reviews the development of inorganic–organic hybrid white-light phosphors, including coordination compounds of small organic molecules, organically templated inorganic compounds (phosphates, borates, sulfides, halides), metal-functionalized organic polymers, and organically coated nanoparticles. [ABSTRACT FROM AUTHOR]

Introduction of photochromic properties into semiconductors confers semiconductors with smart behaviors, color‐related applications, and new modulation approaches. Photochromophores with electron‐transfer (redox) behavior, such as viologen and naphthalene diimide, are ideal functional motifs to design photochromic semiconductors owing to good adaptability to the solid matrix, but their reverse reactions are exclusively realized by the thermal mode, which is slow (in dozens of seconds or longer) and thus significantly hinders real applications in the fields that require high‐speed switching. This study reveals that photoexcitation in the electronic absorption band of the π‐aggregate of viologen cation radicals can successfully trigger reverse electron transfer quickly (in 1 s with a continuous‐wave 808 nm laser at a power density of 5 W cm−2; the photothermal effect is excluded), and the first single‐component all‐optically photochromic semiconductor is accordingly discovered. This discovery breaks through a traditional concept that reverse reactions of viologen compounds can not be triggered by the light, and provides a potential approach to realize all‐optical switch of single‐component photochromic smart semiconductors based on electron‐transfer photochromic functional motifs. [ABSTRACT FROM AUTHOR]

Abstract: Five new thiogermanates, [NiII(dien)2]2(Ge2S6) (dien=diethylenetriamine) (1), [NiII(dien)2](H2pipe)(Ge2S6) (pipe=piperazine) (2), {[MnII(tren)]2(μ 2-Ge2S6)} (tren=N,N,N-tris(2-aminoethyl)amine) (3) and {[MII(tepa)]2(μ 2-Ge2S6)} (M=Mn (4a), Ni (4b); tepa=tetraethylenepentamine), have been obtained solvothermally in the presence of tri-(L3), tetra-(L4) and penta-dentate (L5) chelating amines and transition metal (TM) ions. Single-crystal X-ray diffraction analyses show that compounds 1–2 are comprised of discrete (Ge2S6)4− anions and TM complex (TMC) cations, while compounds 3–4b are composed of each dimeric (Ge2S6)4− anion bridging two TMC cations via TM–S bonds to form a neutral molecule. Notably, two interesting in situ metal/ligand reactions were observed in the solvothermal syntheses of 2 and 3. The present compounds exhibit wide optical gap ranging from 2.94 to 3.39eV and photoluminescence with the emission maxima occurring around 440 (1, 2, 3 and 4b) and 489nm (4a). Magnetic measurements show the presence of weak antiferromagnetic interactions between magnetic centers in the five compounds. [ABSTRACT FROM AUTHOR]

A photochromic inorganic–organic hybrid based on in situgenerated MV2+cation (MV2+= methyl viologen = N,N′-dimethyl-4,4′-bipyridinium) has been obtained, in which a vagarious partial photochromic phenomenon together with its photoluminescence modulation properties are reported for the first time in the inorganic–organic hybrids. [ABSTRACT FROM AUTHOR]

Abstract: Assembly of isonicotinic acid ligand (HL) with metal halide, five new hybrid complexes [CdI2(C5H4NCOOH)(C5H4NHCOO)]·H2O (1), Na n [ZnCl2(C5H4NCOO)] n ·2nH2O (2), [CdX(C5H4NCOO)] n (X=Br (3), I (4)) and [Cd3Cl2(OH)2(C5H4NCOO)2] n (5) were obtained, which display a variety of structural motifs, ranging from zero-dimensional to complicated three-dimensional networks. Complex 1 possesses an isolated unit MX2 that is further connected into 3D networks through hydrogen bonding and π–π stacking interactions. Complex 2 is characterized by an infinite one-dimensional chain of zinc atoms bridged by L− ligands. While complexes 3 and 4 possess X-bridging inorganic chains connected by L− ligands to form a 2D hybrid network structure. In the case of 5, the cadmium(II) cation is bridged by μ3-Cl atom and μ3-OH− group to form a 2-D inorganic layer which is further extended into 3-D framework by bridging L− ligand via Cd–N and Cd–O bonds. The optical properties of 1, 4, and 5 in the solid state are investigated at room temperature and time-dependent DFT (TDDFT) calculation using the B3LYP functional has been performed on 1. The result indicated that the emission band of 1 is attributed to an admixture of MLCT (metal-to-ligand charge–transfer) and LLCT (ligand-to-ligand charge-transfer). [Copyright &y& Elsevier]

Abstract: Four triazole-bridging coordination complexes, [Zn4(ptr)2(SO4)3(μ 3-OH)2(H2O)4] n (1), [Hg(CN)2(ptr)] n (2), [Hg(Cl)2(ptr)] n (3), and [Cu2(μ 2-ptr)2(μ 2-F)2] n (SiF6) n ·2nH2O (4), were synthesized with (m-phenol)-1,2,4-triazole (ptr). Compounds 1–4 with extended structures of 4-substituted 1,2,4-triazole are rarely reported. The layered structure of 1 can be regarded as constructed from the 2-D inorganic backbone of SO4 2−(2) anions bridging [Zn4(μ 3-OH)2(H2O)2]6− subunits with the ptr ligands anchoring to both sides of backbone. Compounds 2 and 3 are the first mercury(II) complexes with 4-substituted 1,2,4-triazole, which feature the ptr ligand acting as a bidentate ligand bridging the Hg(II) atoms to form arciform –Hg–ptr–Hg–ptr chains. The structure of 4 is constructed from the F atoms bridging Cu atoms in symmetrical μ 2-coordination mode to form a zigzag cationic chain with each ptr ligand bridging a pair of Cu atom on the both sides, resulting in a nonplanar 5-membered [Cu2N2F] ring. Fluorescent properties of 1–4 were characterized and the magnetic property of 4 shows antiferromagnetic interaction between the copper(II) ions. [Copyright &y& Elsevier]

Abstract: A novel 3-D inorganic open-framework containing unusual heptanuclear quasi-supertetrahedra, Cd7I12S·3H2O (1), was obtained by hydrothermal reaction and structurally characterized. Optical absorption spectrum reveals that the presence of an optical gap of 2.26eV, indicating that compound 1 is a semiconductor. [Copyright &y& Elsevier]

Abstract: Spontaneous resolution in solvothermal reactions through tuning the volume of the templating and space-filling agents (quaternary ammonium cations) lead to three novel halogeno(cyano)cuprates [R4N][Cu(CN)X] (R=Et, X=Cl, 1; R=Et, X=Br, 2; R=Bu, X=I, 3), which all consist of 1-D helical chains. Compounds 1 and 2 reveal to be mesomeric structures while compound 3 exhibits a nonracemic enantiopure topology. Luminescent studies indicate that all three compounds are potential materials for efficient luminescent materials. [Copyright &y& Elsevier]

New double salts Ag2C2·6AgO2CCHF2 (1), [HPyCH2OH][Ag9(C2)(CF3CO2)9(HPyCH2OH)(H2O)]·0.5H2O (PyCH2OH=4-(hydroxymethyl)pyridine) (2), Ag2C2·5CF3SO3Ag·2MeCN·2H2O (3) and Ag2C2·8CF3SO3Ag·2EtCN·3H2O (4) have been synthesized by dissolving Ag2C2 in an aqueous solution of the corresponding silver salt followed by the addition of an ancillary ligand. Complex 1 has a three-dimensional structure in which unprecedented basket-like silver cages are inter-connected by difluoroacetate ligands. In 2, centrosymmetric (C2)2@Ag14 double cages with each half taking the shape of a triangulated dodecahedron are linked through additional silver atoms to generate an infinite chain, and unsupported silver(I)–silver(I) interactions exist between neighboring chains. Of the two independent 4-(hydroxymethyl)pyridinium ions in 2, one acts in the O-ligating mode, which is observed for the first time, while the other merely serves to provide charge balance and space-filling. Both 3 and 4 are layer-type structures in which the basic building unit is a distorted monocapped octahedron and monocapped trigonal prism, respectively. [Copyright &y& Elsevier]

Three new polymeric silver cyanide complexes AgCN·AgF·4AgCF3CO2·2CH3CH2CN (3), AgCN·AgCF3CF2CO2 (4) and AgCN·2AgCF3SO3·H2O (5) have been obtained by dissolving AgCN in an aqueous solution of AgX (X=CF3CO2, C2F5CO2 or CF3SO3) and AgBF4, and their layer-type crystal structures determined by X-ray crystallography. In the silver-rich environments, all the co-existing ancillary anions display unusual coordination modes: μ4-O,O,O′,O′-trifluoroacetate and pentafluoropropionate and μ4-η1κO:η1κO′:η1κ2O″-triflate. The cyanide ion functions as a μ3-η1κ2C:η1κN bridge in the construction of an unprecedented chain-like [Ag2(CN)]∞ motif in 4. [Copyright &y& Elsevier]

A novel chiral open-framework structural hexanary chalcogenoborate, (K3I)[SmB12(GaS4)3] (1), was obtained by a facile approach using boron as the reducing reagent; it shows weak SHG-activity and is transparent in the mid-IR region. [ABSTRACT FROM AUTHOR]

Scintillators are essential in converting ionizing X‐rays and γ‐rays into visible light, with applications in medical diagnosis, security inspection, and non‐invasive detection. However, current scintillating materials exhibit unclear structure–function relationships. The performance of scintillators is intricately linked to their electronic band structure, particularly the intrinsic properties of excited states. Therefore, investigating the structural factors affecting scintillation performance is crucial for developing new scintillators. Therefore, Ba‐SMOF 1 ([Ba2(PyTS)(CH3OH)2(H2O)4]n) is synthesized using a pyrene‐based organic motif and metal Ba(II) ions, where PyTS4− refers to pyrene‐1,3,6,8‐tetrasulfonate. For the first time, the excited state of a pyrene‐based X‐ray scintillating metal–organic framework (MOF) is determined through comprehensive all‐electron excitation studies, including in situ experimental electron density and wave‐function analysis. The electron density maps exhibit a continuous overlap, attributed to the associative exciton behaviors among the closely packed PyTS4− linkers. These linkers are identified as the sources of both static and dynamic excimer emissions. The electron density studies reveal the role of excimers in pyrene‐based luminophores, highlighting that interchromophoric interactions are key to enhancing the performance of scintillating MOFs. This discovery opens new avenues for the practical application of scintillating MOFs. [ABSTRACT FROM AUTHOR]

Nonlinear optical (NLO) materials are of immense scientific and technological importance. However, debate has long prevailed theoretically regarding the structural origin of the second harmonic generation (SHG) effect. In this work, the experimental electron density (ED) of controversial β‐BaB2O4 (BBO) is studied by high‐resolution X‐ray diffraction, indicating that the [B3O6]3− motif dominates two large non‐zero SHG tensors (d222 and d311) while Ba atoms contribute mostly to the smallest one (d333), and the atomic SHG contributions of terminal O atoms in [B3O6]3− motifs are much larger than those of B and bridged O atoms, clarifying the disputes on its NLO response mechanism. Besides, the contraction of inner electron shells (5s25p6) of the Ba atom and partial covalent behavior of the Ba─O interaction are first observed experimentally. Furthermore, the SHG coefficients of BBO derived from experimental ED are in excellent agreement with those from bulk crystals, providing a high‐efficient and low‐cost method of screening high‐performance NLO materials with just an easy‐to‐obtain tiny crystal. [ABSTRACT FROM AUTHOR]

The study of facile‐synthesis and low‐cost X‐ray scintillators with high light yield, low detection limit and high X‐ray imaging resolution plays a vital role in medical and industrial imaging fields. However, the optimal balance between X‐ray absorption, decay lifetime and excitonic utilization efficiency of scintillators to achieve high‐resolution imaging is extremely difficult due to the inherent contradiction. Here two thermally activated delayed fluorescence (TADF)‐actived coinage‐metal clusters M6S6L6 (M=Ag or Cu) were synthesized by simple solvothermal reaction, where the cooperation of heavy atom‐rich character and TADF mechanism supports strong X‐ray absorption and rapid luminescent collection of excitons. Excitingly, Ag6S6L6 (SC‐Ag) displays a high photoluminescence quantum yield of 91.6 % and scintillating light yield of 17420 photons MeV−1, as well as a low detection limit of 208.65 nGy s−1 that is 26 times lower than the medical standard (5.5 μGy s−1). More importantly, a high X‐ray imaging resolution of 16 lp/mm based on SC‐Ag screen is demonstrated. Besides, rigid core skeleton reinforced by metallophilicity endows clusters M6S6L6 strong resistance to humidity and radiation. This work provides a new view for the design of efficient scintillators and opens the research door for silver clusters in scintillation application. [ABSTRACT FROM AUTHOR]

The study of facile‐synthesis and low‐cost X‐ray scintillators with high light yield, low detection limit and high X‐ray imaging resolution plays a vital role in medical and industrial imaging fields. However, the optimal balance between X‐ray absorption, decay lifetime and excitonic utilization efficiency of scintillators to achieve high‐resolution imaging is extremely difficult due to the inherent contradiction. Here two thermally activated delayed fluorescence (TADF)‐actived coinage‐metal clusters M6S6L6 (M=Ag or Cu) were synthesized by simple solvothermal reaction, where the cooperation of heavy atom‐rich character and TADF mechanism supports strong X‐ray absorption and rapid luminescent collection of excitons. Excitingly, Ag6S6L6 (SC‐Ag) displays a high photoluminescence quantum yield of 91.6 % and scintillating light yield of 17420 photons MeV−1, as well as a low detection limit of 208.65 nGy s−1 that is 26 times lower than the medical standard (5.5 μGy s−1). More importantly, a high X‐ray imaging resolution of 16 lp/mm based on SC‐Ag screen is demonstrated. Besides, rigid core skeleton reinforced by metallophilicity endows clusters M6S6L6 strong resistance to humidity and radiation. This work provides a new view for the design of efficient scintillators and opens the research door for silver clusters in scintillation application. [ABSTRACT FROM AUTHOR]

Reports on the solvothermal synthesis of a mixed-metal polysulfide cluster. Structure of the tetranuclear heterometal polysulfide cluster in the complex [Me4N]3[MoS4Cu3(S5)2]; Use of polysulfide ligands.

[Display omitted] • It is an urgent demand to achieve the multifunctional optical properties of visible photochromism and strong photoluminescence on one material. • The photochromic viologen-based MOFs rarely exhibit strong photoluminescence in both initial and colored states. • We report herein a viologen-based host-guest Eu-MOF with both visible photochromism and strong photoluminescence. • The title compound exhibits visible photochromism arising from photoinduced electron transfer from electron rich host framework to electron deficient guest viologen unit. • The title compound emits strong pink luminescence in both initial and colored states with the luminescence quantum yield of about 31.6%. A viologen-based host–guest metal–organic framework with both visible photochromism and strong photoluminescence was designed and synthesized, namely (H 2 bpyb)[Eu(btec)] 2 (bpyb = 1,4-bis(4-pyridyl)benzene, H 4 btec = 1,2,4,5-pyromellitic acid), providing an effective pathway for designing multifunctional optical materials with comprehensive performance. [ABSTRACT FROM AUTHOR]

The selectivity control of Pd nanoparticles (NPs) in the direct CO esterification with methyl nitrite toward dimethyl oxalate (DMO) or dimethyl carbonate (DMC) remains a grand challenge. Herein, Pd NPs are incorporated into isoreticular metal–organic frameworks (MOFs), namely UiO‐66‐X (X=‐H, ‐NO2, ‐NH2), affording Pd@UiO‐66‐X, which unexpectedly exhibit high selectivity (up to 99 %) to DMC and regulated activity in the direct CO esterification. In sharp contrast, the Pd NPs supported on the MOF, yielding Pd/UiO‐66, displays high selectivity (89 %) to DMO as always reported with Pd NPs. Both experimental and DFT calculation results prove that the Pd location relative to UiO‐66 gives rise to discriminated microenvironment of different amounts of interface between Zr‐oxo clusters and Pd NPs in Pd@UiO‐66 and Pd/UiO‐66, resulting in their distinctly different selectivity. This is an unprecedented finding on the production of DMC by Pd NPs, which was previously achieved by Pd(II) only, in the direct CO esterification. [ABSTRACT FROM AUTHOR]

The selectivity control of Pd nanoparticles (NPs) in the direct CO esterification with methyl nitrite toward dimethyl oxalate (DMO) or dimethyl carbonate (DMC) remains a grand challenge. Herein, Pd NPs are incorporated into isoreticular metal–organic frameworks (MOFs), namely UiO‐66‐X (X=‐H, ‐NO2, ‐NH2), affording Pd@UiO‐66‐X, which unexpectedly exhibit high selectivity (up to 99 %) to DMC and regulated activity in the direct CO esterification. In sharp contrast, the Pd NPs supported on the MOF, yielding Pd/UiO‐66, displays high selectivity (89 %) to DMO as always reported with Pd NPs. Both experimental and DFT calculation results prove that the Pd location relative to UiO‐66 gives rise to discriminated microenvironment of different amounts of interface between Zr‐oxo clusters and Pd NPs in Pd@UiO‐66 and Pd/UiO‐66, resulting in their distinctly different selectivity. This is an unprecedented finding on the production of DMC by Pd NPs, which was previously achieved by Pd(II) only, in the direct CO esterification. [ABSTRACT FROM AUTHOR]

By the coordination assembly of a redox photoactive functional motif and a cyanide-bridged moiety, a cyanide-bridged MnII–FeIII compound with large photoinduced magnetic change at room-temperature due to photoinduced electron transfer was obtanied. This compound also shows unprecedented radical-quenched spin glass in molecule based magnets. [ABSTRACT FROM AUTHOR]

Construction of heterojunctions to photocatalysts is one of the most promising approaches to improve charge separation efficiency; however, the established constructing processes usually require high‐temperature conditions and/or the adding of highly concentrated or expensive exotic species, and the improvement of effective contact and charge exchange between heterojunction components remains a problem. This work proposes an unprecedented "photobreeding" method and realizes the direct growth of Zn nanowires and Mott–Schottky heterojunctions from ZnS or viologen‐coated ZnS microspheres through a photochemical reaction at room temperature without external species, while demonstrating the hypothesis proposed 140 years ago on the formation of Zn in the photochromic process of ZnS. After photobreeding of the heterojunctions, the hydrogen production efficiency of the photocatalysts increases by 2 orders of magnitude. This inexpensive, facile and efficient synthetic method will find applications in H2 production, organic synthesis, CO2 reduction, nitrogen fixation, and so on. [ABSTRACT FROM AUTHOR]

Single‐component semiconductors with photoresponse to full solar spectrum are highly desirable to simplify the device structure of commercial photodetectors and to improve solar conversion or photocatalytic efficiency but remain scarce. This work reports bottom‐up photosynthesis of an air‐stable radical semiconductor using BiI3 and a photochromism‐active benzidine derivative as a photosensitive functional motif. This semiconductor shows photoconductivity to full solar spectrum contributed by radical and non‐radical forms of the benzidine derivative. It has also the potential to detect X‐rays because of strong X‐ray absorption coefficient. This finding opens up a new synthetic method for radical semiconductors and may find applications on extending photoresponsive ranges of perovskites, transition metal sulfides, and other materials. [ABSTRACT FROM AUTHOR]

Photoinduced electron transfer (PET) with the formation of stable radicals plays an important role in many areas. In this work, PET and color change of two sulfone-based donor–acceptor molecules were observed for the first time in the solid state. Generation of radicals was confirmed by experimental and theoretical data. The radicals could be stable in the air and at high temperature (e.g. 105 °C) in the solid state. Introducing an electron-donating substituent (such as –NH2) increases the molecular dipole moment and promotes the PET process. Sulfone-based molecules observed in this work and their analogs may be applied in several potential applications such as photoswitching, photochromism, energy conversion, and photocatalysis. [ABSTRACT FROM AUTHOR]

In contrast to anionic group theory of nonlinear optical (NLO) materials that second‐harmonic generation (SHG) responses mainly originate from anionic groups, structural regulation on the cationic groups of salt‐inclusion chalcogenides (SICs) is performed to make them also contribute to the NLO effects. Herein, the stereochemically active lone–electron‐pair Pb2+ cation is first introduced to the cationic groups of NLO SICs, and the resultant [K2PbX][Ga7S12] (X = Cl, Br, I) are isolated via solid‐state method. The features of their three‐dimensional structures comprise highly oriented [Ga7S12]3− and [K2PbX]3+ frameworks derived from AgGaS2, which display the largest phase‐matching SHG intensities (2.5−2.7 × AgGaS2 @1800 nm) among all SICs. Concurrently, three compounds manifest band gap values of 2.54, 2.49, and 2.41 eV (exceeding the criterion of 2.33 eV), which can avoid two‐photon absorption under the fundamental laser of 1064 nm, along with the relatively low anisotropy of thermal expansion coefficients, leading to improved laser‐induced damage thresholds (LIDTs) values of 2.3, 3.8, and 4.0 times that of AgGaS2. In addition, the density of states and SHG coefficient calculations demonstrate that the Pb2+ cations narrow the band gaps and benefit SHG responses. [ABSTRACT FROM AUTHOR]

Less attention has been paid to the solvent-dependent chirality transformation behavior of coordination compounds when using achiral precursors. We have successfully prepared one known helical achiral compound ( α -[AgL] n ∙ n H 2 O, 1 ) using water or DMSO as a solvent, one new helical homochiral MOF ( β -[AgL] n ∙ n H 2 O, 2 ) using DMF, dimethyl acetamide or ethanol as a solvent, and one new non-helical achiral compound ([Ag 2 L(NO 3 )] n , 3 ) using n -propyl alchohol or cyclohexanol as a solvent, with the V-shaped achiral ligand 3-aminobenzoic acid (HL) as a ligand. Achiral 1 can be converted from chiral isomeric 2 through recrystallization in water. Such successive chirality transformation (achirality → chirality → achirality) behavior is probably proportional the polarity of the used solvent: cyclohexanol ( 3 ) < n -propyl alchohol ( 3 ) < ethanol ( 2 ) < dimethyl acetamide ( 2 ) < DMF ( 2 ) < DMSO ( 1 ) < water ( 1 ). A preliminary study revealed that the isomeric compounds 1 and 2 displayed significantly different photoluminescence. [ABSTRACT FROM AUTHOR]

Abstract: We evaluated the individual atom contributions to the second harmonic generation (SHG) coefficients of LiCs2PO4 (LCPO) by introducing the partial response functionals on the basis of first principles calculations. The SHG response of LCPO is dominated by the metal‐cation‐centered groups CsO6 and LiO4, not by the nonmetal‐cation‐centered groups PO4 expected from the existing models and theories. The SHG coefficients of LCPO are determined mainly by the occupied orbitals O 2p and Cs 5p as well as by the unoccupied orbitals Cs 5d and Li 2p. For the SHG response of a material, the polarizable atomic orbitals of the occupied and the unoccupied states are both important. [ABSTRACT FROM AUTHOR]

Abstract: We evaluated the individual atom contributions to the second harmonic generation (SHG) coefficients of LiCs2PO4 (LCPO) by introducing the partial response functionals on the basis of first principles calculations. The SHG response of LCPO is dominated by the metal‐cation‐centered groups CsO6 and LiO4, not by the nonmetal‐cation‐centered groups PO4 expected from the existing models and theories. The SHG coefficients of LCPO are determined mainly by the occupied orbitals O 2p and Cs 5p as well as by the unoccupied orbitals Cs 5d and Li 2p. For the SHG response of a material, the polarizable atomic orbitals of the occupied and the unoccupied states are both important. [ABSTRACT FROM AUTHOR]

A crystal structure with a diamond-like anionic framework belongs to a non-centrosymmetric macrostructure due to the aligned arrangement of tetrahedral units, meeting the premise of second-order nonlinear optical (NLO) materials. Herein, two new Hg-based sulphides, namely RbHg4Ga5S12 (1) and CsHg4Ga5S12 (2), which are isostructural and crystallise in the trigonal space group R3, are successfully isolated in sealed silica tubes by a solid-state reaction. The features of their three-dimensional open honeycomb frameworks are attributed to the parallel alignment of tetrahedral MS4 (M is disordered by 0.444 Hg and 0.555 Ga) building motifs, accompanied by Rb+ (or Cs+) reseating in the cavities. Notably, although the band gap values of 1 and 2 are 2.30 and 2.36 eV, separately, their thermal expansion anisotropies (0.15 and 0.41, respectively) are favourable for achieving laser-induced damage thresholds (5.6 and 5.8 times that of AgGaS2 for 1 and 2, respectively). In addition, the strong polarisability of tetrahedral MS4 building motifs in the diamond-like anionic structures is responsible for the promising second-harmonic generation (SHG) intensities (1.1 and 1.8 times that of AgGaS2 for 1 and 2, respectively) in the particle size range of 50–75 μm with non-phase-matchable behaviour at 1910 nm. Furthermore, theoretical investigation elaborates that electron transitions in compounds 1 and 2 mainly occur from valence band S-3p to conduction band Hg-6s and Ga-4s states, demonstrating that the linear and nonlinear optical properties originate primarily from the synergy of tetrahedral MS4 units. [ABSTRACT FROM AUTHOR]

The exploration and development of second-order nonlinear optical (NLO) materials in the middle- and far infrared (MFIR) region are important and high profile topics in the fields of NLO, solid-state chemistry and laser. Common MFIR NLO materials are chalcogenides, halides, and iodates, which have a wide MFIR transparent range and large NLO coefficients. This review summarizes recent achievements on MFIR NLO materials, and specifically focuses on their crystal structures and NLO properties. Compared to known materials, the common choice for cations are alkali-metal Li, Na, K, Rb and Cs, the coin-metal Ag, and the alkali-earth metal Ba. Exploring mixed-anions materials could be one of the most promising solutions to obtaining NLO materials with both large second-harmonic generation (SHG) intensities and high laser induced damage thresholds (LIDTs). This review also summarizes functional moiety theory to elucidate the design of promising NLO materials. [ABSTRACT FROM AUTHOR]

Three new ternary rare-earth zirconium chalcogenides, Ce 2 ZrSe 5 ( 1 ), Pr 2 ZrSe 5 ( 2 ) and Nd 2 ZrSe 5 ( 3 ), have been synthesized by a facile solid-state route with boron as the reducing reagent. They crystallize in the space group Pnma of the orthorhombic system, belonging to the U 3 Se 5 structure type. Their 3-D structures are constructed by parallel polyanionic {[ZrSe 5 ] 6– } n chains and LnSe 8 bicapped trigonal prisms. The magnetic susceptibilities' data indicate their antiferromagnetic-like behavior without magnetic order down to 2 K. The structural relationships among several similar structures are discussed, together with the lanthanide contraction in the Ln 2 ZrSe 5 system. [ABSTRACT FROM AUTHOR]

A quaternary metal chalcogenide, namely K2CdGe3S8 (I), is obtained through a high-temperature solid-state approach. Compound I crystallizes with the non-centrosymmetric space group P212121. It features a 2D layer structure with [CdGe3S8] layers consisting of tetrahedral GeS4 and CdS4 units, and counter K+ embedded between the layers. The compound exhibits a powder second-harmonic generation (SHG) response of ~0.1 times that of KH2PO4 (KDP) with phase-matchable character at the laser wavelength of 1064 nm. Remarkably, it has a wide band gap (3.20 eV), which corresponds to a favorable high laser-induced damage threshold of 6.7 times that of AgGaS2. In addition, the calculated birefringence (Δn) is 0.039 at the wavelength of 1064 nm, which satisfies the Δn criteria for a promising infrared NLO material. [ABSTRACT FROM AUTHOR]

Diffusion of diethyl ether into a reaction mixture of zinc salts, crown ether and calcium chloride in tetra­hydro­furan (THF) led to the title compound, [Ca(C12H24O6)(H2O)3][ZnCl4]. The cation is linked to the anion via O—H⋯Cl hydrogen bonding. [ABSTRACT FROM AUTHOR]

The structure of the title compound, [ZnCl2(H2O)2]·C12H24O6·H2O, contains the Zn atom with tetra­hedral geometry and two coordinated water mol­ecules linked to two 18-crown-6 macrocycles (residing on inversion centres) by O—H⋯O inter­actions. A water mol­ecule of crystallization further links the metal salt and one of the crown ether macrocycles. [ABSTRACT FROM AUTHOR]

Two new quaternary selenides AAg3Ga8Se14, (A = Rb, 1; Cs, 2) were synthesised via solid-state reaction in sealed silica tubes. Compounds 1 and 2 crystallised in the monoclinic space group Cm (no. 8) and their three-dimensional [Ag3Ga8Se14]− anionic frameworks were comprised of AgSe4 and GaSe4 tetrahedrons. Their UV-Vis-near infrared diffuse reflectance spectra showed that 1 and 2 possessed wide band gaps of 2.17 and 2.10 eV, respectively. Notably, under incident laser irradiation at 1910 nm, compounds 1 and 2 presented moderate second-harmonic generation responses of 0.6 and 0.7 × AgGaS2, respectively, with phase-matching behaviours due to the parallel arrangement of nonlinear optical (NLO) functional tetrahedral AgSe4 and GaSe4 units. The laser-induced damage thresholds of 1 and 2 were estimated to be 25.4 and 18.0 MW cm−2, respectively, which were 2.1 and 1.5 times the threshold of AgGaS2. This study revealed that the title selenides, which were constructed from tetrahedral units arranged in a parallel array, are promising infrared NLO materials. [ABSTRACT FROM AUTHOR]

Reduction of nitric acid reaction (2NO + HNO3 + 3CH3OH → 3CH3ONO + 2H2O) can convert by-product nitric acid into raw material methyl nitrite in the coal to ethylene glycol (CTEG) technology. This not only realizes the efficient recycling of nitrogen resources but also plays a crucial role in mitigating environmental pollution. Despite being a promising catalyst, the Pd/C catalyst face challenges due to its high metal loading, substantial loss rate, and consequent issues of poor stability, presenting obstacles in meeting industrial requirements. To address this issue, a defect strategy has been employed to develop a low-loaded 0.3% Pd/NC catalyst with robust metal-support interaction, resulting in a significant enhancement of catalyst stability. Remarkably, even after undergoing five cycles, the catalyst maintains a high nitric acid conversion rate of 90%. This improved performance can be attributed to the strong metal-support interaction driven by electron transfer from the nitrogen-doped carbon (NC) substrate to the Pd nanoparticles evident in the Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma (ICP) results. This interaction effectively suppresses the leaching of the active Pd nanoparticles, leading to significantly enhanced stability and a noticeable reduction in the loss rate. Raman spectrum and electron paramagnetic resonance (EPR) results can further reveal that the increase in the defect density lead to the strong metal-support interaction after nitrogen doping (pyridinic-N-dominated). These findings highlight the significant potential of the Pd/NC catalyst and its applicability in expediting the industrialization process of catalyst.Graphical Abstract: Reduction of nitric acid reaction (2NO + HNO3 + 3CH3OH → 3CH3ONO + 2H2O) can convert by-product nitric acid into raw material methyl nitrite in the coal to ethylene glycol (CTEG) technology. This not only realizes the efficient recycling of nitrogen resources but also plays a crucial role in mitigating environmental pollution. Despite being a promising catalyst, the Pd/C catalyst face challenges due to its high metal loading, substantial loss rate, and consequent issues of poor stability, presenting obstacles in meeting industrial requirements. To address this issue, a defect strategy has been employed to develop a low-loaded 0.3% Pd/NC catalyst with robust metal-support interaction, resulting in a significant enhancement of catalyst stability. Remarkably, even after undergoing five cycles, the catalyst maintains a high nitric acid conversion rate of 90%. This improved performance can be attributed to the strong metal-support interaction driven by electron transfer from the nitrogen-doped carbon (NC) substrate to the Pd nanoparticles evident in the Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma (ICP) results. This interaction effectively suppresses the leaching of the active Pd nanoparticles, leading to significantly enhanced stability and a noticeable reduction in the loss rate. Raman spectrum and electron paramagnetic resonance (EPR) results can further reveal that the increase in the defect density lead to the strong metal-support interaction after nitrogen doping (pyridinic-N-dominated). These findings highlight the significant potential of the Pd/NC catalyst and its applicability in expediting the industrialization process of catalyst. [ABSTRACT FROM AUTHOR]

A precise control strategy has been employed to regulate the electronic structure and catalytic microenvironment of Pd nanoparticles through the synergistic effect of metal nodes and linker groups within the UiO-66. The higher electronegativity TiIV species and nitro-functionalized linker groups as electron acceptors effectively reduced the electron density of Pd species and synergistically promoted the activation of CO and MN. As a result, Pd@Ti-Zr-UiO-66-NO 2 exhibits excellent performance in direct CO esterification to DMC. [Display omitted] • Electronic structure and microenvironment of Pd@UiO-66 can be finely modulated. • The Pd@Ti-UiO-66-NO 2 enhances the reaction of CO to dimethyl carbonate. • The electron transfer from Pd to support is responsible for high-performance. While the microenvironment around metal catalytic sites is recognized to be crucial in heterogeneous catalysis, its roles in CO esterification to dimethyl carbonate remain subtle. Herein, Pd nanoparticles are confined into the metal–organic frameworks with TiIV metal substitutions and functional linker groups, namely Pd@Ti-Zr-UiO-66-X (X = H, NH 2 , NO 2). The partial substitution of metal nodes by Ti species can dramatically enhance the activity of CO, and synergistically improves catalytic performance with electron-withdrawing functionalized nitroxide linkers. As a result, Pd@Ti-Zr-UiO-66-NO 2 exhibits superior conversion of CO (67.5%), selectivity for DMC (83.5%, based on all products) and WTY for DMC (1725 g·kg cat −1·h−1) much higher than those of Pd@Zr-UiO-66-H with conversion of CO (46.4%), selectivity for DMC (87%) and WTY for DMC (1175 g·kg cat −1·h−1). Based on results of experimental and DFT calculation, the synergistic effect of highly electronegative Ti species and nitro-functional linker groups with electron-withdrawing ability realizes the precise control of the electronic structure and microenvironment of Pd NPs. The number of charges transferred from Pd NPs to Zr-UiO-66 and Ti-Zr-UiO-66-NO 2 increased from 1.83 to 2.69 e, respectively. The microenvironment of electron-deficient palladium species and Ti-Zr-UiO-66-NO 2 promotes the activation of MN and CO, which exhibits a superior performance in direct CO esterification to dimethyl carbonate. This study not only provides a new approach for rational modulation of the chemical microenvironment of metal centers and optimization of catalytic performance but also offers important insights for the design of heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

As early as 2001, the need for the 'functional motif theory' was pointed out, to assist the rational design of functional materials. The properties of materials are determined by their functional motifs and how they are arranged in the materials. Uncovering functional motifs and their arrangements is crucial in understanding the properties of materials and rationally designing new materials of desired properties. The functional motifs of materials are the critical microstructural units (e.g. constituent components and building blocks) that play a decisive role in generating certain material functions, and can not be replaced with other structural units without the loss, or significant suppression, of relevant functions. The role of functional motifs and their arrangement in materials, with representative examples, is presented. The microscopic structures of these examples can be classified into six types on a length scale smaller than ∼10 nm with maximum subatomic resolution, i.e. crystal, magnetic, aperiodic, defect, local and electronic structures. Functional motif analysis can be employed in the function-oriented design of materials, as elucidated by taking infrared non-linear optical materials as an example. Machine learning is more efficient in predicting material properties and screening materials with high efficiency than high-throughput experimentation and high-throughput calculations. In order to extract functional motifs and find their quantitative relationships, the development of sufficiently reliable databases for material structures and properties is imperative. [ABSTRACT FROM AUTHOR]

Mixed-anionic compounds have caught considerable attention due to their flexible coordination manners and abundant physical properties. Four new chalcohalides RbIn4S6Cl (1), CsIn4S6Cl (2), Pb5Sn3S10Cl2 (3) and Pb5Sn3Se10Cl2 (4) were successfully obtained by the high-temperature halide salt flux method. Compounds 1 and 2 have layered structures that consist of octahedral InS6 and aliovalent-anionic InS3Cl units. Compounds 3 and 4 feature 3-D structural frameworks built by [Pb4SnQ8Cl4]6− and [PbSn2Q6]2− (Q = S and Se) polyhedral chains, in which partial Pb2+ cations are coordinated by Q2− and Cl− anions. Compounds 1–4 have optical band gaps close to the wavelength range of visible light and exhibit significant photocurrent responses of 28.75 nA cm−2, 55.12 nA cm−2, 19.58 mA cm−2, and 36.12 μA cm−2 with on/off ratios 30.0, 2.5, 15.7 and 2.6, respectively, implying their potential for photovoltaic applications. To the best of our knowledge, compound 3 has the largest photocurrent response among all non-oxides. In addition, the activation energies of 1–4 are well below 0.3 eV, which makes these compounds interesting for potential applications in electrochemical devices. This work sheds light on the exploration of promising photocurrent response materials in the mixed-anionic compound system. [ABSTRACT FROM AUTHOR]

Copper chalcogenides have drawn considerable attention due to their prominent semiconducting properties. A new Cu-containing semiconductor, namely, CsCuS4 (1), was obtained by a halide salt flux method. Its structure featured 1D infinite ∞1 [CuS4] − chains, where the polysulfide anion S42− was relatively rare in Cu chalcogenides. The compound was multifunctional and exhibited significant photocurrent, humidity sensitivity, and proton conductivity properties. Specifically, it exhibits an "on" state photocurrent response of 0.95 μA cm−2 and an "off" state photocurrent response of 0.55 μA cm−2 with good reversibility. The humidity-sensitive resistance in dry air (10% RH) could reach up to six orders of magnitude higher than that in wet air (100% RH). Compound 1 showed an activation energy of 0.19 eV and may have potential electrochemical applications. [ABSTRACT FROM AUTHOR]

The detection of X-rays has always been a frontier of scientific research. An Eu-MOF with both X-ray-induced photochromic and scintillation properties has been synthesized through the combination of a photochromism-active viologen ligand and rare earth Eu element with high-efficiency absorption of X-rays. In a bright environment, Eu-MOF exhibits different color changes under high-energy X-rays and low-energy X-rays, which can effectively distinguish X-rays. Eu-MOF can also be used for X-ray detection by scintillation properties in dark environments. This work provides a new perspective on the design of multifunctional materials that can perform simple X-ray detection in different environments. [ABSTRACT FROM AUTHOR]

CO direct esterification to dimethyl oxalate (DMO) has important industrial application value. Pd-based heterogeneous catalysts have been often utilized for this reaction. However, the effects of defect structures causing by the different morphologies of the support on the catalytic performance has not been investigated sufficiently. In this work, three different morphologies of CeO2 support (denoted as rod, cube, and octahedron) loading Pd were synthesized, and further investigated their catalytic activities for CO direct esterification to DMO. The Pd/CeO2-rod catalyst exhibited the best CO conversion compared with Pd/CeO2-cube and Pd/CeO2-octa. The results of Raman and XPS show that CeO2-rod has the highest oxygen vacancy concentration than those of CeO2-cube and CeO2-octa. In addition, it was found that partial interfacial electrons transfer from Pd to CeO2 support at the interface from the result of XPS. More intriguingly, the result of in situ DRIRS of CO exhibits that the partial interfacial electrons transfer from CeO2 to Pd, resulting from oxygen vacancies serve as a charge compensator to promote partial electrons transfer. The enriched electron of Pd would promote the adsorption and activation of CO, thus enhancing the catalytic activity. This work will provide a general understanding of the support effect to catalytic performance, which induced by the oxygen vacancies. [ABSTRACT FROM AUTHOR]

Abstract: Different composition, thickness and structure of CoNi thin films supported on glassy carbon were prepared by electrochemical codeposition. Potential step method was applied to prepare CoNi thin films with different composition which was controlled by varying the concentration ratio of Co2+/Ni2+ (x:y) in the deposition solution, thus this type of CoNi thin film was defined as CoNi(x:y). Nevertheless, CoNi thin films with different thickness and structure (denoted as CoNi(n)) were synthesized in a fixed Co2+/Ni2+ solution under cyclic voltammetric conditions by varying the cyclic numbers (n) within a defined potential range. AES and EDS analysis revealed that the atomic ratio of Co/Ni in the film (including both outer and inner layer) was in good accordance with the initial Co2+/Ni2+ ratio. XRD investigation indicated that the CoNi(20:0) and CoNi(15:5) thin films were hexagonal closed-packed (hcp) structure, however, the CoNi(10:10), CoNi(5:15) and CoNi(0:20) thin films were face centered cubic (fcc) structure. SEM studies demonstrated that the CoNi(x:y) thin films were uniformly composed of irregular nanoparticles. In the case of CoNi(n), with n increasing, the structure of nanoparticles inside the CoNi thin films underwent a transition from imperfectly spherical particles to multiform particles, and finally to irregular polyhedral particles, accompany with an increase of average size. In situ FTIR reflection spectroscopic studies demonstrated that the mainly chemisorbed CO species (COad) on CoNi(x:y) surfaces were transferred from linearly bonded CO (COL) to bridge bonded CO (COB) as a function of the content of Ni and the crystal phase structure of CoNi thin films. CoNi(x:y) and CoNi(n) thin films all exhibited anomalous IR properties, corresponding respectively to abnormal IR effects (AIREs), Fano-like IR effects and surface-enhanced IR absorption effects. AIREs characterized mostly with inversion of IR band was found on CoNi(x:y), CoNi(4), CoNi(8) thin films which were dominated by irregular or imperfectly spherical particles. Fano-like IR bands with positive-going peak on the lower wavenumbers side were observed in cases of CO adsorbed on CoNi thin films composed mainly of multiform nanoparticles, typically on CoNi(25) thin film. IR features were finally changed into surface-enhanced IR absorption as CO adsorbed on the CoNi(50) thin film, i.e., the CoNi thin film was dominated by smooth irregular polyhedral particles. [Copyright &y& Elsevier]

Pd-based heterogeneous nanocatalysts have wide application in chemical industry. However, the traditional synthesis process contains multi-steps such as impregnation, dry, calcination and reduction. The pre-synthesis nanoparticles process can reduce the steps, but need to remove the surfactants, which are added in the synthesis process. In this work, a facile one-pot hydrothermal synthesis process named as single molecular precursor method was successfully developed to prepare Pd/Mg(OH)2 heterogeneous nanocatalysts with clean surface. The as-synthesized Pd/Mg(OH)2 heterogeneous nanocatalysts show excellent performance for CO direct esterification to dimethyl oxalate (DMO). The WTY (weight time yield) of DMO can reach the high-performance of 2544 g kgcat.−1 h−1, while the conversion of CO is 62.6% and selectivity to DMO is 90.8%. The single molecular precursor method developed by this work can be extended to other supported noble metal nanocatalysts. [ABSTRACT FROM AUTHOR]

Five coordination polymers 1–5with four types of (4,4) layers havebeen synthesized through anew strategy of designing their crystal structures based on (4,4)topology. Compound [Co(adc)(bpp)(H2O)]n(1) presents a 2-D structurewith 2-fold homointerpenetration of layer A, while the2-D compound {[Ni(adc)(bpp)2(H2O)]2·bpp}n(2) presents 2-fold heterointerpenetration of layer Bandlayer C. Compound [Zn(adc)(bpp)·DMF]n(3) displays a typical 2-D→ 3-D parallel interpenetrating structure of layer D. Compounds [Ni(Cladc)(bpp)(H2O)]n(4) and [Co(Cladc)(bpp)(H2O)]n(5) are isomorphousand display similar structures to 1. (H2adc= 4,4′-azodibenzoic acid, ClH2adc = 3,3′-dichloro-4,4′-azodibenzoicacid, bpp = 1,3-di(4-pyridyl)propane, DMF = N,N-dimethylformamide). Luminescence propertiesand thermal stabilities of 1–5havebeen explored. [ABSTRACT FROM AUTHOR]

Abstract: In our investigation of non-centrosymmetric rare earth sulfides in the La3AgSnS7/KBr, LaAlGeS5/NaBr, HoAlGeS5/KBr, ErAlGeS5/NaBr, Er3AgGeS7/KBr and La3NaSnS7/NaBr systems, five compounds belonging to the R6B2C2Q14 family have been obtained. These compounds crystallize in the P63 space group, and the crystal data are as follows—La3AgSnS7: a =10.3780(15)Å, c =5.9900(12)Å, Z =2; La3Ge0.25GeS7: a =10.2970(15)Å, c =5.8120(12)Å, Z =2; Ho3Ge0.272(10)GeS7: a =9.6480(14)Å, c =5.7920(12)Å, Z =2; Er3Ge0.330(10)GeS7: a =9.5930(14)Å, c =5.8490(12)Å, Z =2; La3Sn0.25SnS7: a =10.2770(15)Å, c =6.0030(12)Å, Z =2. Single-crystal analysis indicated that the crystal structures consist of three types of building block: LnS n , MS4, and AgS3 (for La3AgSnS7) or MS6 units (for Ln3M x MS7, Ln=La, Ho, Er; M=Ge, Sn; 1/4≤ x ≤1/2), as any other compounds belonging to the R6B2C2Q14 family. Ln3M x MS7 (Ln=La, Ho, Er; M=Ge, Sn; 1/4≤ x ≤1/2) are deficient compounds with the B sites occupied partly by M(II), and/or M(IV). [Copyright &y& Elsevier]

Abstract: Four homotrinuclear linear coordination compounds with bridging ligand of (m-phenol)-1,2,4-triazole, [Mn3(L)6(H2O)6](ClO4)6 (1), [Ni3(L)6(H2O)6](BF4)6·4DMF (2), [Cd3(L)6(H2O)6](ClO4)6· 2H2O·2DMF·2EtOH (3), [Zn3(L)8(H2O)4](BF4)4(SiF6)·2EtOH·12H2O (4), have been synthesized and structurally determined. The structures consist of three metal ions in linear arrangements, linked to each other by two pairs of three N1, N2 bridging triazole ligands. The negative value of J suggests that antiferromagnetic interaction exists in 1. Green fluorescence of 2 and 4 with emissions at 518nm for 2 and 524 for 4 is possibly assigned to LMCT. The energy gaps of the compounds 2 and 4 are 1.82 and 1.97eV, respectively, which suggests that the two materials behave as semiconductors. [Copyright &y& Elsevier]

Abstract: A novel triazole-bridging polynuclear silver(I) complex, [Ag4(ptr)6](NO3)4 ·4H2O (1), was synthesized with (m-phenol)-1,2,4-triazole (ptr), which is the first discrete tetranuclear complex containing 4-substituted triazoles. The compound features blue fluorescence with a broad emission at 432nm excited at 363nm, possibly originating from the π–π∗ transition of the triazole ring. [Copyright &y& Elsevier]