Modulating ß-Keto-enamine-Based Covalent Organic Frameworks for Photocatalytic Atom-Transfer Radical Addition Reaction.

The atom-transfer radical addition (ATRA) reaction simultaneously forges carbon-carbon and carbon-halogen bonds. However, frequently-used photosensitizers such as precious transition metal complexes, or organic dyes have limitations in terms of their potential toxicity and recyclability. Three ß-ketoenamine-linked covalent organic frameworks (COFs) from 1,3,5-triformylphloroglucinol and 1,4-phenylenediamines with variable transient photocurrent and photocatalytic activity have been prepared. A COF bearing electron-deficient Cl atoms displayed the highest photocatalytic activity toward the ATRA reaction of polyhalogenated alkanes to give halogenated olefins under visible light at room temperature. This heterogeneous photocatalyst exhibited good functional group tolerance and could be recycled without significant loss of activity.

A stable tetrazagallole and its radical anion dimer.

The reaction of the carbazole ligand supported Ga(I) compound LGa(THF) (3) and 1-azido-4-(tert-butyl)benzene (ArN3) afforded the first stable tetrazagallole LGaN4Ar2 (4) bearing a three-coordinate Ga atom. Reduction of 4 with elemental potassium resulted in the radical dimer {[K(18-c-6)]+[4]˙-}2, featuring a strong antiferromagnetic interaction between the spin centers.

Se-Incorporation Stabilizes and Activates Metastable MoS2 for Efficient and Cost-Effective Water Gas Shift Reaction.

Although the water gas shift (WGS) reaction has sparked intensive attention for the production of high-purity hydrogen, the design of cost-efficient catalysts with noble metal-like performance still remains a great challenge. Here, we successfully overcome this obstacle by using Se-incorporated MoS2 with a 1T phase. Combining the optimized electronic structure, additional active sites from edge sites, and a sulfur vacancy based on the 1T phase, as well as the high surface ratio from the highly open structure, the optimal MoS1.75Se0.25 exhibits superior activity and stability compared to the conventional 2H-phase MoS2, with poor activity, large sulfur loss, and rapid inactivation. The hydrogen production of MoS1.75Se0.25 is 942 µmol, which is 1.9 times higher than MoS2 (504 µmol) and 2.8 times higher than MoSe2 (337 µmol). Furthermore, due to the lattice stabilization via Se-incorporation, MoS1.75Se0.25 exhibited excellent long-term stability without obvious change in more than 10 reaction rounds. Our results demonstrate a pathway to design efficient and cost-efficient catalysts for WGS.

An MOF-like Interpenetrated 2D Plus 2D to 3D Inorganic Grid Assembled by Linear Inorganic Pillars, Structures, and Properties in Supercapacitance.

Remarkable progresses regarding pure inorganic frameworks and metal-organic frameworks (MOF) have been made. However, pure inorganic frameworks with MOF-like grid structures are rarely reported due to the weakness of inorganic moiety as a long linear linker. We report herein a fascinating inorganic framework assembled by a [Ge4S10]4- cluster node and a linear [-Cu-MS4-Cu-] (M = Mo (1) and W (2)) inorganic pillar. Their network shows MOF-like orthogonal structure with two interpenetrated two-dimensional (2D) plus 2D to 3D framework and a 1D nano tunnel. Electrodes with crystalline sample of 1 and 2, inorganic sulfide framework, were prepared, and their quasi-capacitance behaviors were investigated. Electrochemical performances were evaluated by cyclic voltammetry and galvanostatic charge-discharge techniques in CsOH, KOH, NaOH, and LiOH electrolytes. The results revealed that the crystal materials exhibit moderate specific capacitance values that are comparable to those of porous sulfide materials.

Photo-electroactive ternary chalcogenido-indate-stannates with a unique 2-D porous structure.

A lot of ternary In-Sb-Q (Q = S, Se) chalcogenido-metalates with amines or complex cations have been recently reported for their diverse structures, however, such a type of In-Sn-Q chalcogenido-metalate has been rarely announced. Herein, we report a series of 2-D In-Sn-Q compounds prepared using a metal-phenanthroline cationic template, [M(Phen)3](In2Sn2Q8)·(amine)·nH2O (M = Ni(II), Fe(II) or Co(II); amine = cyclohexylamine (Cha) or 1,6-diaminohexane (Dah); Q = S or Se). Their anions are isostructural and a 2-D porous network with large 16-tetrahedron-rings. The 2-D network joint of In-Sn-Q is a (In/Sn)3Q3 six-membered ring, which is different from the Sn3Q4 pseudosemicube of most 2-D Sn-Q binary compounds. The materials exhibit photocurrent response properties measured using a photo-electrochemical cell. The result shows that (1) the selenides exhibit more intense photocurrents than the sulfides and (2) the current intensity is related to the metal-phenanthroline cations.

Ion pair charge-transfer thiogermanate salts [MV]2Ge4S10·xSol: solvent induced crystal transformation and photocurrent responsive properties.

As most of the chalcogenidometalate anions are well-known electron-rich systems, design and preparation of ion pair compounds, by integrating an organic acceptor (A) with an inorganic chalcogenidometalate donor (D), are an attractive strategy to obtain new functional materials. We report herein the single-crystal structures and properties of three new ion pair charge-transfer (IPCT) compounds by incorporating thiogermanates with methylviologen (MV(2+), N,N'-dimethyl-4,4'-bipyridinium dication), [MV]2Ge4S10·xSol (Sol = solvent). Sharp and fast solvent-induced color changes and switchable fluorescence emission are observed for the compounds. The weak interactions that relate to the solvent and ions in the structures are likely the key points to modulate the cation-anion charge-transfer. A photocurrent response is observed for the photoelectric system of the IPCT compound upon repetitive switching of light on and off.

[Ni(dap)3]4[As10Cu2S18]: a new thioarsenate containing the rare [As3CuS6] cluster with mixed-valence As2+/As3+ ions.

A new mixed-valence thioarsenate(II,III) [Ni(dap)3]4-[As10Cu2S18] (1, dap = diaminopropane) has been solvothermally synthesized and structurally characterized. 1 features a new heterometallic thioarsenate [As10Cu2S18](8-) with mixed valence As(2+)/As(3+) ions, which is constructed by combination of the chair-shaped tetramer cyclo-[As4S8] and the rare heterometallic cluster [As3CuS6]. 1 is the first example of transition metal ions encapsulated within mixed-valent thioarsenates(II,III). The optical properties of 1 have also been investigated.

Ionic crystals of {[Ni(phen)3]2Ge4S10}·xSol, showing solid-state solvatochromism and rapid solvent-induced recrystallization.

Thiogermanates, {[Ni(phen)(3)](2)Ge(4)S(10)}·xSol (Sol = 4MeOH·12H(2)O (1) and 24H(2)O (2)) were prepared and characterized by single-crystal structure analysis. There are large quantities of the solvent molecules that cocrystallize with the anions and cations and form a strong hydrogen bonding network (O-H···S and O···H-O-H···O). Reversible yellow-pink color change with fast speed was found for these compounds, when the crystals were immersed in alcohol solvents and water alternately. The time of the solvent-induced color change relates to the molecular size and structure of the alcohols. The smaller the molecule is, the faster the color change will be. The fastest color change was found by using the methanol solvent that took only about one second. The color change also relates to the ratio of water/alcohol. The solvatochromism phenomenon is accompanied with a rapid solvent-induced recrystallization that is verified by the XRD patterns.

A wheel-shaped indium-telluride nanocluster [In18Te30(dach)6]6-: its formation and structure.

The preparation and crystal structure of a large wheel-shaped indium-telluride compound are reported. The inorganic cluster is decorated with 1,2-diaminocyclohexane molecules that play an important role in the formation of the nanoring. A related new 1D polymeric InTe compound is also presented in order to understand the effect of acidity on the formation of the ring structure.

Indium sulfide clusters integrated with 2,2'-bipyridine complexes.

Supertetrahedral compounds of chalcogenometalates (T3 cluster compounds) integrated with Ni-bpy (bpy = 2,2'-bipyridine) complex were prepared by a solvothermal technique. The compound [Ni(bpy)(3)](3)[H(4)In(10)S(20)]·bpy·2EG·6H(2)O (Mb-InS-1) (EG = ethylene glycol) consists of discrete T3 clusters of [H(4)In(10)S(20)](6-) with three [Ni(bpy)(3)](2+) cations. The compound [Ni(bpy)(3)](2)[H(2)In(10)S(19)]·bpy·2HEA·2H(2)O (Mb-InS-2) (EA = ethanolamine) is a 1-D polymer, in which zigzag T3 cluster chains are charge balanced by metal-bpy complex cations. The compound [Ni(bpy)(3)](7)[H(4)In(40)S(74)]·7Hbpy·3HEA·8H(2)O (Mb-InS-3) is a 2-D T3 polymer with cation layers of [Ni(bpy)(3)](2+). Integrating M-bpy complex cations into chalcogenido structures has been made with the aim of improving the photoabsorption of the materials. The electronic spectra showed the new bands of cation-anion charge-transfer (CACT) that is mainly caused by the S···H-C(py) contacts between the InS T3 supertetrahedral clusters and the [Ni(bpy)(3)](2+) cations.

Anion-cation charge-transfer properties and spectral studies of [M(phen)3][Cd4(SPh)10] (M = Ru, Fe, and Ni).

Three anion-cation compounds 1-3 with formula [M(phen)(3)][Cd(4)(SPh)(10)]·Sol (M = Ru(2+), Fe(2+), and Ni(2+), Sol = MeCN and H(2)O) have been synthesized and characterized by single-crystal analysis. Both the cations and anion are well-known ions, but the properties of the co-assembled compounds are interesting. Molecular structures and charge-transfer between the cations and anions in crystal and even in solution are discussed. These compounds are isomorphous and short inter-ion interactions are found in these crystals, such as π···π stacking and C-H···π contacts. Both spectroscopic and theoretical calculated results indicate that there is anion-cation charge-transfer (ACCT) between the Ru-phen complex dye and the Cd-SPh cluster, which plays an important role in their photophysical properties. The intensity of the fluorescent emission of the [Ru(phen)(3)](2+) is enhanced when the cation interacts with the [Cd(4)(SPh)(10)](2-) anion. The mechanism for the enhancement of photoluminescence has been proposed.

Diamino-diamido tetrathiafulvalene for the sensing of anions and cations: a view in electrochemistry and structure.

A new cation- and anion-sensitive system based on a TTF derivative with a diamino-diamido moiety (H(2)L) has been studied. The results of cyclic voltammetry indicated that the redox potentials of the protonated H(2)L (H(4)L(2+)) selectively respond to later transition metal cations and some oxo anions. Solid-state structures of the cation-anion compounds formed by H(4)L(2+) and oxo anions were characterized crystallographically, which is helpful to understand the matter of the sensitivity for the anion. There are two types of hydrogen bonds in these compounds, one is with an amino group and the other is with an amido group. The shift of the redox potential is obviously related to formation of hydrogen bonding with the amido group. The packing structures of these cation-anion compounds are arranged to layered sandwiched structures assembled by an oxo-anion layer and two TTF layers through hydrogen bonding.

Metal-carboxylate coordination polymers with redox-active moiety of tetrathiafulvalene (TTF).

Though numerous metal-organic frameworks or polymers have been reported, the organic building blocks are usually not redox-active. On the other hand, some mono-, di- or tri-nuclear compounds with tetrathiafulvalene (TTF) have been prepared, although little is known about the coordination polymers combined with paramagnetic metals and organic TTF ligands. We report herein a series of coordination polymers of copper(II) and manganese(II) with TTF dicarboxylate ligand (L). Compound 1, [CuL(2,2-bpy)](n), is a one-dimensional (1-D) coordination polymer with five-coordinated square-pyramidal Cu(II) centers. Mn(II) complex 2, [MnL(2,2-bpy)](n), also takes a 1-D structure, showing a double-bridged mode by carboxylate groups. The 4,4-bipyridine compound 3, [MnL(4,4-bpy)(H(2)O)](n)·CH(3)CN, takes a 2-D grid network. A zinc(II) compound 4, [ZnL(4,4-bpy)(H(2)O)](n)·CH(3)CN, isomorphous structure with 3, is also presented. The electrochemical properties of the solid-state compounds were investigated by cyclic voltammetry using surface-modified electrodes. As usually observed in TTF derivatives, two sets of redox-waves were observed. The values of E(1/2)(1) of compounds 1-4 are in the order of 2(Mn) ≈ 3(Mn) < 1(Cu) < 4(Zn), indicating that the metal coordination can affect the potential shift of the TTF ligand. Weak antiferromagnetic exchanges are observed for compounds 1, 2, and 3.

Transition metal complexes as linkages for assembly of supertetrahedral T4 clusters.

Tn clusters are usually connected into frameworks by sulfur bridges. A new type of T4 compounds in which the clusters are linked by both sulfur bridges and transition metal complexes are described.

Tetrathiafulvalene-tetracarboxylate: an intriguing building block with versatility in coordination structures and redox properties.

The synthesis of the transition metal coordination polymers containing a tetrathiafulvalene (TTF) moiety substituted with a tetracarboxylate group of the formulas [Mn(L)(0.5)(phen)(H(2)O)(2)](n).nH(2)O (1), [Mn(L)(0.5)(bpy)](n).nH(2)O (2), [Mn(L)(0.5)(bpy)(CH(3)OH)](n).2nH(2)O (3), and [Cu(L)(0.5)(bpy)(DMF)](n).n(DMF) (4) (L(4-) = TTF-tetracarboxylate; phen = 1,10-phenanthroline; bpy = 2,2'-bipyridine) is reported. Complex 1 is a two-dimensional (2-D) coordination polymer constructed of infinite carboxylate bridged Mn(II) chains and TTF moiety linkages. Complex 2 possesses a 3-D polymeric structure formed by infinite -Mn-(O-C-O)(2)-Mn- bridged one-dimensional (1-D) chains, which are further coordinated by TTF-tetracarboxylate ligands of two different orientations. Both complexes 3 and 4 show 1-D extended chain structures but are constituted by different dinuclear metal(II) units with a -Mn-(O-C-O)(2)-Mn- bridge in 3 and a -Cu-(O)(2)-Cu- bridge in 4. Electrochemical study of the solid-state compounds attests to the redox activity of the coordination system. Magnetic investigations reveal the existence of antiferromagnetic interactions between magnetic centers in complexes 3 and 4, while in 1, the paramagnetic metallic centers are isolated, in agreement with the solid-state structure.

{[SmCl(en)4][In2Te4]}n: an indium telluride with a one-dimensional sinusoidal chain.

The title compound, catena-poly[[chloridotetrakis(ethylenediamine-kappa(2)N,N')samarium(III)] [indium(III)-di-mu-tellurido-indium(III)-di-mu-tellurido]], {[SmCl(C(2)H(8)N(2))(4)][In(2)Te(4)]}(n), consists of a one-dimensional sinusoidal {[InTe(2)](-)}(n) anionic chain and [SmCl(en)(4)](2+) cations (en is ethylenediamine). The only other previously reported lanthanide analogue, viz. [LaCl(en)(4)][In(2)Te(4)], contains more usual linear one-dimensional {[InTe(2)](-)}(n) anion chains [Chen, Li, Chen & Proserpio (1998). Inorg. Chim. Acta, 273, 255-258]. The one-dimensional polymeric {[InTe(2)](-)}(n) chain is built of InTe(4) tetrahedra sharing opposite edges. The Sm(III) ion in the [SmCl(en)(4)](2+) cation is nine-coordinated by eight N atoms from four bidentate en molecules and by one chloride ion to form a monocapped square-antiprismatic geometry. The presence or absence of N-H...Cl hydrogen bonding is shown to affect the conformation of the anion.

Effects of protonation and metal coordination on intramolecular charge transfer of tetrathiafulvalene compound.

A protonated bifunctional pyridine-based tetrathiafulvalene (TTF) derivative (DMT-TTF-pyH)NO3 and a copper(II) complex Cu(acac)2(DMT-TTF-py)2 have been obtained and studied. Electronic spectra of the protonated compound show a large ICT (intramolecular charge transfer) band shift (Deltalambda=136 nm) compared with that of the neutral compound. Cyclic voltammetry also shows a large shift of the redox potentials (DeltaE1/2(1)=77 mV). Theoretical calculation suggests that the pyridium substituent is a strong pi-electron acceptor. Crystal structures of the protonated compound and the metal complex have been obtained. The dihedral angle between least-squares planes of the pyridyl group and the dithiole ring might reflect the intensity of the ICT effect between the TTF moiety and the pyridyl group. It is also noteworthy that the TTF moiety could be oxidized to TTF2+ dication by Fe(ClO4)(3).6H2O when forming a metal complex, while the protonated TTF derivative can only be oxidized to the TTF*+ radical cation by Fe(ClO4)(3).6H2O even with an excess amount of the Fe(III) salt, which can be used to control the oxidation process to obtain neutral TTF, TTF*+ radical cation, or TTF2+ dication.

One-dimensional indium sulfides with transition metal complexes of polyamines.

Three new indium sulfides, [Ni(dien)2]0.5[InS2] (dien = diethylenetriamine) (1), [Ni(dap)3]0.5[InS2] (dap = 1,2-diaminopropane) (2), and [Ni(tepa)]2[In4S7(SH)2].H2O (tepa = tetraethylenepentamine) (3), have been prepared under solvothermal conditions and characterized by single-crystal X-ray diffraction. Compounds 1 and 2 consist of discrete 1-D {[InS2]-} infinity chains with complex cations as charge-compensating ions, while compound 3 consists of a novel 1-D anionic chain constructed from arachno-shaped In4S11 clusters. The sulfide chain of 3 coordinates into the complex cations via the nonterminal S atoms of the polymeric anion, forming a covalently linked organic-inorganic hybrid compound.

Synthesis of a selenidostannate(IV), [Mn(tepa).Sn3Se7]n, demonstrating the transformation from achiral to chiral and dimeric to polymeric structure.

Although a number of chalcogenostannates have been obtained by using [M(amine)m]n+ as the structure director, these materials with chiral metal complex ions are usually achiral because they are a racemic mix of chiral complex cations. A chiral selenidostannate, [Mn(tepa).Sn3Se7]n (1; tepa = tetraethylenepentamine), containing incorporated [Mn(tepa)]2+ units, is reported herein. The unique structure is just like a grapevine appended with chiral grapes. In the same reaction, a centrosymmetric compound, [Mn(tepa)]2(mu2-Sn2Se6) (2), in which the Sn2Se64- anion acts as a bridge coordinating to [Mn(tepa)]2+ cations, has also been obtained. This is a reaction-time-related process in which compound 2 transformed gradually to 1 after prolonging the reaction time. This phenomenon demonstrates a transformation from achiral to chiral and dimeric to polymeric selenidostannate.

Luminescent 2-D double-layered polymer, [(CuI)4(CH3SCH3)3]infinity, containing helical chains constructed by flower-basket-shaped Cu4I4 clusters.

A new route for the synthesis of coordination compounds with dimethyl sulfide ligand is reported; the prepared compound is a novel 2-D framework with a 1-D right-handed and left-handed helical structure, which is unique in the sense that the fundamental units are unusual Cu4I4 clusters.