Silver-Rich Hybrid Framework Iodide Based on [Ag8I6]2+ Clusters Displays Low-Temperature Dual Emission and Luminescence Thermochromism.

Cluster-based framework metal iodides have diverse structures and excellent luminescence properties, and show promising applications in sensing and solid-state lighting. However, the design and synthesis of these materials remain great challenges because excess I- ions introduced into the synthesis systems decrease the condensation degree of M-I units. In this work, a new strategy is developed to control the condensation behavior of Ag-I units, and a new silver-rich cluster-based framework iodide [DabcoAg8I6(SPh)2]n (1) (Dabco = 1,4-diazabicyclo [2.2.2] octane) has been synthesized under solvothermal conditions in the presence of silver thiophenolate (AgSPh)n. Compound 1 features a three-dimensional (3-D) cluster-based framework with a pillared layer structure composed of cationic [Ag8I6]2+ clusters bridged by SPh- and Dabco, and displays low-temperature dual emission and luminescence thermochromism.

Cotemplating Assembly and Structural Variation of Three-Dimensional Open-Framework Sulfides.

Open-framework sulfides (H3O)KCu6Ge2S8 (1) and (H3O)RbCu6Ge2S8 (2) were prepared by a cotemplating strategy. This shows that alkali-metal and protonated water cations act as cotemplates to direct the three-dimensional open-framework sulfides. These templates direct two types of one-dimensional channels that arrange parallelly, and different types of templates reside in different types of channels. By introduction of the Cs cation into the synthetic systems of 1 and 2, (H3O)K0.6Cs0.4Cu6Ge2S8 (3) and (H3O)Rb0.75Cs0.25Cu6Ge2S8 (4) were obtained. Compound 3 has a different anionic framework from those of 1 and 2, while 4 is isostructural with 1 and 2.

Solvothermal Syntheses and Characterizations of Four Quaternary Copper Sulfides BaCu3MS4 (M = In, Ga) and BaCu2MS4 (M = Sn, Ge).

Hydro(solvo)thermal syntheses of quaternary copper sulfides containing alkaline earth metal ions remain a great challenge because of the low solubility of Cu-S compounds. Herein, a new facile solvothermal method was developed, and four quaternary copper sulfides, i.e., BaCu3InS4 (1), BaCu3GaS4 (2), BaCu2SnS4 (3), and BaCu2GeS4 (4), were prepared using excess sulfur as a mineralizer. Compound 1 possesses a novel three-dimensional (3D) anionic [Cu3InS4]2- framework constructed by an 8-membered ring of [Cu4S4] and [Cu2In2S4] alternatively. Compound 2 features a unique 3D anionic [Cu3GaS4]2- framework composed of [Cu3GaS10]n14n- anionic chains and 8-membered rings, in which [Cu4S4] and [Cu2Ga2S4] reside alternatively. Compounds 3 and 4 feature 3D anionic [Cu2MS4]2- (M = Sn, Ge) frameworks composed of CuS4 and MS4 tetrahedra with Ba2+ located in the channels. It is worth noting that different 3D Cu-S frameworks exist in the title crystal structures, in which main group ions are incorporated. This paper provides a new synthetic strategy for new quaternary sulfides.

Unusual Flexibility of Microporous Sulfides during Ion Exchange.

Open-framework chalcogenides with ion-exchange capacity are promising materials for removing hazardous heavy-metal ions and for capturing radioactive Cs+. However, research on the exchange mechanism is limited, especially for the framework chalcogenides that have multiple bridging anions. Generally, open-framework chalcogenides that have multiple bridging anions at the window or wall of the channels are rigid during the ion-exchange process. We show here that microporous sulfides with µ3-S2- (where µ3 = triple bridging mode) at the windows exhibit framework flexibility upon ion exchange. Three new microporous sulfides Na4Cu8Ge3S12·2H2O (1), Na3(Hen)Cu8Sn3S12 (where en = ethylenediamine) (2) and (dap)2(Hdap)4Cu8Ge3S18 (where dap = 1,2-diaminopropane) (3) were synthesized under solvothermal conditions. Compounds 1 and 2 contain a copper-rich framework composed of icosahedral [Cu8S12]16- units linked via monomeric GeS44- or SnS44- tetrahedral units, whereas compound 3 features an expanded framework composed of icosahedral [Cu8S12]16- units interconnected with dimeric Ge2S64- units. These compounds exhibit unusual ion-exchange properties. Specifically, the frameworks of 1 and 2 (with µ3-S at the small windows) show "breathing action" upon ion exchange of K+ or Rb+, which have relative large sizes, and compound 3 exhibits framework flexibility upon Cs+ ion exchange with both space group and channels changed.

Radical-Enhanced Intersystem Crossing in New Bodipy Derivatives and Application for Efficient Triplet-Triplet Annihilation Upconversion.

A long-lived triplet excited state of the well-known fluorophore boron dipyrromethene (Bodipy) was observed for the first time via efficient radical-enhanced intersystem crossing (EISC). The triplet state has been obtained in two dyads in which the Bodipy unit is linked to a nitroxide radical, 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO), with two different length spacers. The photophysical properties were studied with steady-state and time-resolved transient optical spectroscopies and electron spin resonance (cw-ESR and TR-ESR). The fluorescence of Bodipy units is significantly quenched in the dyads, and the spin-polarized TEMPO signals were observed with TR-ESR, generated by a radical triplet pair mechanism. Efficient EISC (ΦT = 80%) was observed for the dyad with a shorter linker, and the triplet state lifetime of the Bodipy chromophore is exceptionally long (62 µs). The EISC takes 250 ps. Poor ISC was observed for the dyad with a longer linker. The efficient ISC and long-lived triplet excited state in this flexible system are in stark contrast to the previously studied rigid EISC systems. The EISC effect was employed for the first time to perform triplet-triplet annihilation (TTA) upconversion (quantum yield ΦUC = 6.7%).

Coordination-Induced Syntheses of Two Hybrid Framework Iodides: A Thermochromic Luminescent Thermometer.

Two new 3D hybrid framework iodides, Hmta[(Hmta)Ag4I4] (1; Hmta = hexamethylenetetramine) and [(Hmta)2Ag8I6]I2 (2), have been synthesized under solvothermal conditions. Compound 1 consists of a neutral 3D framework built up from alternation of the tetrahedral Ag4I4 unit and Hmta with dia-b topology. Compound 2 features a 3D cationic framework with flu topology, constructed by cationic [Ag8I6](2+) units linked with Hmta. Tetrahedral Hmta plays crucial structure-directing roles in the formation of these 3D frameworks with high symmetry. The temperature-dependent photoluminescent measurement reveals luminescent thermochromism of the compounds, the emission maximum of which shows a gradual blue shift with increasing temperature. The results indicate that 1 is a promising wavelength- and intensity-dependent luminescent thermometer applicable in two different temperature ranges.

Syntheses and Characterization of Chiral Zeolitic Silver Halides Based on 3-Rings.

The synthesis of chiral zeolites remains a significant challenge because the primary tetrahedral building units are achiral and weak interactions exist between the guest and host frameworks. Here, we present the syntheses and characterization of three new chiral zeolitic halides, [H3(Dabco)2]Ag3X6 (X = Br (1) or I (2), Dabco = 1,4-diazabicyclo[2.2.2]octane) and [H2(Dabco)][(Dabco)Ag4I6] (3). Compounds 1 and 2 are isostructural, containing a 4-connected zeolitic framework built up from 3-ring units, with high-charge [H3(Dabco)2]3+ located in chiral cages. Compound 3 contains a similar zeolitic [Ag3I6]3- framework to that of 2, but a [Ag(Dabco)]+ unit is incorporated in each 3-ring, with [H2(Dabco)]2+ located in channels. These frameworks are chiral, representing the first examples of chiral zeolitic halides. The chirality transference of the frameworks for 1 and 2 was attributed to the template effect of the chiral [H3(Dabco)2]3+ through strong electrostatic interactions and multiple hydrogen-bond interactions. For compound 3, direct coordination interactions play important roles in the chirality transference from the chiral Dabco ligand to the framework.

Mild solvothermal syntheses and characterization of layered copper thioantimonates(III) and thioarsenate(III).

The new copper thioantimonates(III) and thioarsenate(III) Rb2Cu2Sb2S5 (1), Cs2Cu2Sb2S5 (2), and Rb8Cu6As8S19 (3) have been synthesized solvothermally. Compound 1 contains a [Cu2SbS3] net to which [Sb2S4] chains adhere through Cu-S bonds and Sb-Cu interactions to give a layered structure. In compound 2, the layer is formed by edge-sharing tetrahedral CuS4 chains linked by dimeric [Sb2S5] units. The layered structure in compound 3 is constructed by helical chains built from [Cu3S7] moieties and dimeric [As2S5] units which are further connected by tetrameric [As4S9] groups. Their optical and thermal properties have been investigated.

Mild solvothermal syntheses of thioargentates A-Ag-S (A = K, Rb, Cs) and A-Ag-Ge-S (A = Na, Rb): crucial role of excess sulfur.

A series sulfides of A-Ag-S (1-3; A = K, Rb, Cs), Na5AgGe2S7 (4), and Rb2Ag2GeS4 (5) have been prepared solvothermally in the presence of excess sulfur. Among these compounds, 4 is a new compound that has a novel layered structure; the others were obtained under mild conditions. The results showed that excess sulfur could increase the solubility of silver sulfide and lower the synthetic temperature effectively. The mineralizer effect of excess sulfur is discussed in detail.

Photoactive chiral metal-organic frameworks for light-driven asymmetric α-alkylation of aldehydes.

Chiral metal-organic frameworks (MOFs) with porous and tunable nature show promise as heterogeneous asymmetric catalysts. Through incorporating the stereoselective organocatalyst L- or D-pyrrolidin-2-ylimidazole (PYI) and a triphenylamine photoredox group into a single framework, we have developed two enantiomeric MOFs, Zn-PYI1 and Zn-PYI2, to prompt the asymmetric α-alkylation of aliphatic aldehydes in a heterogeneous manner. The strong reductive excited state of the triphenylamaine moiety within these MOFs initiated a photoinduced electron transfer, rendering an active intermediate for the α-alkylation. The chiral PYI moieties acted as cooperative organocatalytic active sites to drive the asymmetric catalysis with significant stereoselectivity. Control experiments using the lanthanide-based metal-organic frameworks Ho-TCA and MOF-150, assembled from 4,4',4"-nitrilotribenzoic acid, as catalysts suggested that both the photosensitizer triphenylamine moiety and the chiral organocatalyst D-/L-PYI moiety were necessary for the light-driven α-alkylation reactions. Further investigations demonstrated that the integration of both photocatalyst and asymmetric organocatalyst into a single MOF makes the enantioselection superior to that of simply mixing the corresponding MOFs with the chiral adduct. The easy availability, excellent stereoselectivity, great separability, and individual components fixed with their well-defined porous and repeating structures make the MOF a versatile platform for a new type of tandem catalyst and cooperative catalyst.

In situ growth of hierarchical phase junction CdS on a H-mordenite zeolite for enhanced photocatalytic properties.

A kind of cadmium sulfide (CdS) nanocomposite with different crystalline phases was grown on the surface of H-mordenite zeolite (HMOR) by a chemical liquid-phase co-precipitation method. In this work, 2 wt% CdS@HMOR photocatalytic material with the coexistence phase (hexagonal phase and cubic phase) of cadmium sulfide was grown on the surface of HMOR by controlling the reaction temperature and ammonia concentration. Photocatalytic degradation of methylene blue (MB) was used as an index to detect the photocatalytic performance of materials. The results indicated that the photocatalytic degradation efficiency of the system with HMOR was significantly improved in comparison to that without HMOR (CdS, 40.34%, 0.2578 h-1). It was found that 2 wt% CdS@HMOR had the best photocatalytic activity. The degradation rate of MB was 84.15% in 2 h, and the degradation rate constant was 0.8884 h-1. When 1.5 ml H2O2 was introduced into the system, the degradation rate of MB was increased to 98.98%, and the degradation rate constant was 1.9976 h-1. SEM, HRTEM, PL, EIS and photocurrent showed that the cubic and hexagonal phases of CdS were in contact with each other on the HMOR surface, forming a good electron transport. By XRD, XPS and SEM tests, the results of materials after four cycles of reactions showed that the structure of the 2 wt% CdS@HMOR was still stable. Therefore, HMOR may provide a good support for CdS, and the synergistic effect between them is beneficial for the occurrence of photocatalytic reactions. HMOR can act as an electron receptor to inhibit the recombination of carriers. The homo-junction between different phases of CdS on the surface of HMOR is beneficial to the separation of photo-induced carriers. These results indicate that the construction of phase heterojunctions on zeolites and the synergism among them are a method for improving the photocatalytic activity.

Copper-rich framework sulfides: A(4)Cu(8)Ge(3)S(12) (A = K, Rb) with cubic perovskite structure.

Two copper-rich open-framework sulfides, K(4)Cu(8)Ge(3)S(12) (1) and Rb(4)Cu(8)Ge(3)S(12) (2), have been synthesized under solvothermal conditions. Compounds 1 and 2 are isostructural and contain icosahedral [Cu(8)S(12)](16-) clusters as basic building blocks. These clusters are primitive cubic packed and connect to one another by discrete Ge(4+) ions to generate 3D copper-rich Cu-Ge-S framework and form 3D channels along 100 directions where the alkali metal cations reside. These two open-framework sulfides crystallize in cubic perovskite structure.

Syntheses and characterization of a series of silver-thioantimonates(III) and thioarsenates(III) containing two types of silver-sulfur chains.

Three framework silver-thioantimonates, K(3)Ag(9)Sb(4)S(12)(1), Rb(3)Ag(9)Sb(4)S(12)(2), and Cs(3)Ag(9)Sb(4)S(12)(3), and one layered silver-thioarsenate, CsAg(2)AsS(3)(4), have been synthesized solvothermally in the presence of thiophenol as a mineralizer. Compounds 1, 2, and 3 are isostructural and contain infinite silver-sulfur chains [Ag(9)S(12)](15-). These chains are connected to one another by the antimony atoms to generate wide channels along the [001] direction where the alkali metal cations reside. The structure of 4 consists of helical chains [Ag(2)S(3)](4-) linked by the arsenic atoms to form layers with potassium ions between the layers.

Syntheses, structures, and photocatalytic properties of open-framework Ag-Sn-S compounds.

Four open-framework Ag-Sn-S compounds K2Ag2Sn2S6 (1); K2Ag2SnS4 (2); Rb2Ag2SnS4 (3); and Cs2Ag2SnS4 (4) have been synthesized using a solvothermal method. Compound 1 possesses a unique three-dimensional (3D) structure in which Ag+ ions are two-coordinated. Compounds 2-4 have the same layered structure in which Ag+ ions are tetrahedrally coordinated. Photocatalytic degradation properties of methylene blue have been investigated and compound 1 displays excellent photodegradation activities. The photoelectric response properties, optical properties, and theoretical calculations of these compounds have also been studied.

Photo-switched wettability on an electrostatic self-assembly azobenzene monolayer.

A simple electrostatic self-assembly technique was used to fabricate a photo-switched azobenzene monolayer, on which superhydrophobicity and a large reversible CA change could be realized.

(H(2)en)(2)Cu(8)Sn(3)S(12): a trigonal CuS(3)-based open-framework sulfide with interesting ion-exchange properties.

(H(2)en)(2)Cu(8)Sn(3)S(12) contains a trigonal CuS(3)-based framework into which Sn(4+) ions are incorporated, and exhibits multiple channel systems and interesting ion-exchange properties.

New framework iodoargentates: M(en)3Ag2I4 (M=Zn, Ni) with tridymite topology.

Two novel framework compounds, Zn(en) 3Ag2I4 (1) and Ni(en) 3Ag2I4 (2), have been synthesized by a self-assembly reaction. Both of them contain an unexpected framework, Ag2I4(2-) with tridymite topology, and the discrete M(en)3(2+) cations are located in the channels. Their thermal properties and circular dichroism spectra were investigated.

K2Ag6Sn3S10: a quaternary sulfide composed of silver sulfide layers pillared by zigzag chains 1infinity[SnS3]2-.

A novel framework K(2)Ag(6)Sn(3)S(10) was synthesized solvothermally and characterized by single-crystal diffraction. The framework comprises [Ag(6)SnS(4)](2+) cationic layers pillared by [SnS(3)](2)(-) zigzag chains formed by vertex-sharing SnS(4) tetrahedra, and potassium ions are located in 1D channels. This compound crystallizes in the orthorhombic Pbcn space group with a = 24.0201(2) A, b = 6.4017(3) A, c = 13.3056(4) A, Z = 4. Its thermal and optical properties are studied.

A solvothermal synthesis and the structure of K4Ag2Sn3S9 x 2KOH.

A novel layered K(4)Ag(2)Sn(3)S(9) x 2KOH was synthesized solvothermally. A mixture of ethanol and HSCH(2)CH(SH)CH(2)OH was used for the synthesis. The HSCH(2)CH(SH)CH(2)OH plays an important role and appears to serve as a mineralizer for the solvothermal reaction. A layer comprises Sn(3)S(9)(6)(-) clusters linked by Ag(+) ions and possesses two types of 1D channels in which potassium ions are located. The compound crystallizes in the monoclinic P2(1)/m space group [a = 7.8071(2) A, b = 27.3508(1) A, c = 10.5008(2) A, alpha = 90 degrees, beta = 103.874(1) degrees, gamma = 90 degrees, Z = 4]. Its crystal structure, composition analysis, and IR are presented.