Metal-Free Selective Ortho-C-H Amidation of Hypervalent(III) Iodobezenes with N-Methoxy Amides under Mild Conditions.

A metal-free selective ortho-C-H amidation of aryl iodines(III) with the use of N-methoxy amides as aminating reagents under mild conditions is described here. In the protocol, excellent chemoselectivity and high regioselectivity were obtained. Notably, the iodine substituent rendered the amidation product suitable to be used for further elaboration.

Single-Crystal Superstructures via Hierarchical Assemblies of Giant Rubik's Cubes as Tertiary Building Units.

Intricate superstructures possess unusual structural features and promising applications. The preparation of superstructures with single-crystalline nature are conducive to understanding the structure-property relationship, however, remains an intriguing challenge. Herein we put forward a new hierarchical assembly strategy towards rational and precise construction of intricate single-crystal superstructures. Firstly, two unprecedented superclusters in Rubik's cube's form with a size of ≈2×2×2 nm3 are constructed by aggregation of eight {Pr4 Sb12 } oxohalide clusters as secondary building units (SBUs). Then, the Rubik's cubes further act as isolable tertiary building units (TBUs) to assemble diversified single-crystal superstructures. Importantly, intermediate assembly states are captured, which helps illustrate the evolution of TBU-based superstructures and thus provides a profound understanding of the assembly process of superstructures at the atomic level.

Photoredox-Catalyzed Acyl Lactonization of Alkenes with Aldehydes: Synthesis of Acyl Lactones.

An acyl lactonization of alkenes with aldehydes under visible-light photoredox catalysis is described. With the protocol, a broad scope of alkenoic acids and aldehydes could be compatible and good functional group tolerance is obtained. A series of acyl lactones are obtained with isolated yields ranging from 50-95%. Mechanistic studies revealed that the transformation should proceed via a radical chain process.

Visible-Light Photoredox-Catalyzed Sulfonyl Lactonization of Alkenoic Acids with Sulfonyl Chlorides for Sulfonyl Lactone Synthesis.

A visible-light photoredox-catalyzed sulfonyl lactonization of unsaturated carboxylic acids with sulfonyl chlorides is described. This reaction features good functional group tolerance and a broad substrate scope, providing a simple and efficient protocol to access a wide range of sulfonyl lactones in high to excellent yields. Preliminary mechanistic investigations suggested that a free-radical pathway should be involved in the process.

Copper-Catalyzed Intermolecular C(sp2)-H Amination with Electrophilic O-Benzoyl Hydroxylamines.

A copper-catalyzed intermolecular electrophilic amination of benzamides with O-benzoyl hydroxylamines was achieved with the assistance of an 8-aminoquinolyl group. With this protocol, good compatibility was observed for a variety of aryl amides and heteroaryl amides, and excellent tolerance with various functional groups was achieved. Significantly, the monoaminated product was overwhelmingly delivered under the simple reaction conditions. Preliminary mechanistic investigations suggested that a radical pathway should be excluded and C-H activation be potentially the rate-determining step.

Hybrid iodoplumbates with metal complexes: syntheses, crystal structures, band gaps and photoelectric properties.

With the in situ-generated [Pb(MCP)4]2+ (HMCP+ = 1-methyl-4-(carboxyl)pyridinium) or [M(phen)3]2+ (M = Co, Fe and Ni; phen = 1,10-phenanthroline) complexes as structural directing agents and charge-balancing ions, we solvothermally synthesized and structurally characterized four new organic-inorganic hybrid iodoplumbates. Compound K2[Pb(MCP)4]Pb3I10 (1) represents the first K+ and [Pb(MCP)4]2+ co-templated hybrid haloplumbate, and exhibits a curve-like anionic layer of [Pb3I10]n4n-. Compounds [M(phen)3]Pb2I6·CH3CN (M = Co (2), Fe (3) and Ni (4)) have isostructural phases, and feature a one-dimensional (1D) [Pb2I6]n2n- anionic chain characteristic of pyramid-like [PbI5] units. The optical property studies show that compounds 1-4 exhibit semiconductor behaviors with the band gaps of 1.98-2.68 eV. In addition, the title compounds exhibited interesting photoelectrical responsive properties, with the photocurrent density in the order of 1 > 3 > 2 > 4. The thermal stabilities of the title compounds 1-4, as well as the theoretical band structure and density of states (DOS) of compounds 1 and 2 have also been studied.

Template Thermolysis to Create a Carbon Dots-Embedded Mesoporous Titanium-Oxo Sulfate Framework for Visible-Light Photocatalytic Applications.

An organo-templated titanium-oxo sulfate of the formulation (H2nep)[TiO(SO4)2] (denoted as TiOS, nep = N-ethylpiperazine) was synthesized under solvent-free conditions. The framework of TiOS is assembled from the [TiO(SO4)2]n2n- infinite chains interconnected by the H2nep cations through H-bond networks. After thermal treatment under vacuum conditions, the organic template H2nep was partially decomposed and converted into N-doped carbon dots (N-CDs), resulting in the N-CDs@TiOS composite material with retained crystallinity of the parent TiOS. The thermolysis of organic templates generates meso-cavities in the framework, rendering N-CDs@TiOS with a mesoporous structure. Photoelectrochemical and photocatalytic experiments show that the presence of N-CDs substantially improved visible-light-driven photocatalytic activity of N-CDs@TiOS compared to that of TiOS. The template thermolysis strategy gives an effective approach to construct the CDs-sensitized Ti-based mesoporous open-framework materials for visible-light photocatalytic applications.

Synthesis of titanium-oxo macrocyles and their catalytic properties for oxidative desulfurization.

Two macrocyclic titanium-oxo clusters, namely, [Ti32(µ3-O)8(µ2-O)8(OCH2CH2O)32(OCH2CH2OH)16(BTA)16]·44H2O (BTA = butyrate) and [Ti32(µ3-O)8(µ2-O)8(OCH2CH2O)32(OCH2CH2OH)16(DMBTA)16(HDMBTA)2]·24H2O (DMBTA = 2,2-dimethylbutyrate) were synthesized and structurally characterized. The framework of the Ti32-oxo macrocycle was cyclically fixed by the double-deprotonated ethylene glycolate ligands, which exhibit an inner cavity of about 1.2 × 1.2 nm. The catalytic properties of the Ti32-oxo macrocycles towards the oxidative desulfurization (ODS) reaction were investigated. The structure-dependent catalytic properties towards oxidative desulfurization were observed for the Ti32-oxo macrocycles functionalized with the different carboxylate ligands.

[Ba13Sb36Cl34O54]8-: high-nuclearity cluster for the assembly of nanocluster-based compounds.

Herein, we report two nanocluster-based compounds built on an unprecedented cluster [Ba13Sb36Cl34O54]8-, which represents the first example of a discrete alkaline earth (AE)-containing oxochloride cluster and the largest Sb-based oxohalide cluster to date; the proton-conducting property of the compounds was investigated.

Copper(II)-Catalyzed Alkene Aminosulfonylation with Sodium Sulfinates For the Synthesis of Sulfonylated Pyrrolidones.

A copper-catalyzed direct aminosulfonylation of unactivated alkenes with sodium sulfinates for the efficient synthesis of sulfonylated pyrrolidones is described. This reaction features good functional group tolerance and wide substrate scope, providing an efficient and straightforward protocol to access this kind of pyrrolidones. Moreover, preliminary mechanistic investigations disclosed that a free-radical pathway might be invovled in the process.

Selective O-Cyclization of N-Methoxy Aryl Amides with CH2Br2 or 1,2-DCE via Palladium-Catalyzed C-H Activation.

A selective O-cyclization of N-methoxy aryl amides with CH2Br2 or 1,2-DCE (1,2-dichloroethane) via palladium-catalyzed C-H activation has been described. New C(sp3)-O and C(sp2)-C(sp3) bonds are forged simultaneously with the assistance of an N-methoxy amide group, and good functional group tolerance in substrates is observed. Preliminary mechanistic investigations show that the process may involve a five-membered palladacycle intermediate.

Titanium-oxo clusters functionalized with catecholate-type ligands: modulating the optical properties through charge-transfer transitions.

Four phenylphosphonate-stabilized titanium-oxo clusters with varying functional ligands, namely, [Ti8(µ3-O)2(µ2-O)2(µ2-OiPr)4(OiPr)8(O3PC6H5)4(cat)2] (cat = catecholate), [Ti8(µ3-O)2(µ2-O)2(µ2-OiPr)4(OiPr)8(O3PC6H5)4(O2C10H6)2] (O2C10H6 = naphthalene-2,3-diolate), [Ti6(µ3-O)2(µ2-O)2(µ2-OiPr)4(OiPr)6(O3PC6H5)2(4-DMAB)2] (4-DMAB = 4-dimethylaminobenzoate), and [Ti6(µ3-O)2(µ2-O)2(µ2-OiPr)4(OiPr)6(O3PC6H5)2(4-CBA)2] (4-CBA = 4-cyanobenzoate) were synthesized and structurally characterized. The introduction of catecholate ligands effectively extended the visible absorption region up to 670 nm and reduced the band gap to 2.1 eV. DFT calculations revealed that the ligand-based energy levels could effectively modify the band structure of titanium-oxo clusters. The ligand-to-core charge transfer (LCCT) transition from the functional ligands to the cluster core is responsible for the low-energy charge transfer states. Photoelectrochemical and photocatalytic experiments show that functional ligands have significant influence on the physicochemical properties of titanium-oxo clusters.

Phosphonate-Stabilized Titanium-Oxo Clusters with Ferrocene Photosensitizer: Structures, Photophysical and Photoelectrochemical Properties, and DFT/TDDFT Calculations.

The metal-to-core charge transfer (MCCT) transition in sensitized titanium-oxo clusters is an important process for photoinduced electron injection in photovoltaic conversion. This process resembles most closely the Type II photoinjection in dye-sensitized solar cells. Herein we report the synthesis and photophysical and photoelectrochemical (PEC) properties of the phosphonate-stabilized titanium-oxo clusters containing the ferrocenecarboxylate ligands. These ferrocene-containing clusters exhibit intense visible absorption extended up to 600 nm along with low optical band gaps of ∼2.2 eV. The low-energy transitions of these clusters were systematically investigated by UV-vis spectroscopy and DFT/TDDFT calculations. The combined experimental and computational studies suggest that the ferrocenecarboxylate-substituted titanium-oxo clusters form a donor-acceptor (D-A) system. The low-energy transition of these clusters primarily involves the MCCT from the iron center to TiO cluster core. The TiO core structure and phosphonate ligands both have great influence on the PEC properties of the clusters. This work provides valuable examples for the sensitized titanium-oxo clusters in which electron injection takes place via MCCT transition.

A 4-dimethylaminobenzoate-functionalized Ti6-oxo cluster with a narrow band gap and enhanced photoelectrochemical activity: a combined experimental and computational study.

Organic donor-π-bridge-acceptor (D-π-A) dyes with arylamines as an electron donor have been widely used as photosensitizers for dye-sensitized solar cells (DSSCs). However, titanium-oxo clusters (TOCs) functionalized with this kind of D-π-A structured dye-molecule have rarely been explored. In the present study, the 4-dimethylaminobenzoate-functionalized titanium-oxo cluster [Ti6(µ3-O)6(OiPr)6(DMABA)6]·2C6H5CH3 (DMABA = 4-dimethylaminobenzoate) was synthesized and structurally characterized by single-crystal X-ray diffraction. For comparison, two other Ti6-oxo clusters, namely [Ti6(µ3-O)6(OiPr)6(AD)6] (AD = 1-adamantanecarboxylate) and [Ti6(µ3-O)2(µ2-O)(µ2-OiPr)4(OiPr)10(DMM)2] (DMM = dimethylmalonate), were also studied. The DMABA-functionalized cluster exhibits a remarkably reduced band gap of ∼2.5 eV and much enhanced photocurrent response in comparison with the other two clusters. The electronic structures and electronic transitions of the clusters were studied by DFT and TDDFT calculations. The computational results suggest that the low-energy transitions of the DMABA-functionalized cluster have a substantial charge-transfer character arising from the DMABA → {Ti6} cluster core ligand-to-core charge transfer (LCCT), along with the DMABA-based intra-ligand charge transfer (ILCT). These low-energy charge transfer transitions provide efficient electron injection pathways for photon-to-electron conversion.

A ferrocenecarboxylate-functionalized titanium-oxo-cluster: the ferrocene wheel as a sensitizer for photocurrent response.

Sensitized titanium-oxo clusters (TOCs) have attracted growing interest. However, reports on TOCs incorporated with a metal complex as photosensitizers are still very rare. In the present work, the organometallic complex ferrocene was used as a sensitizer for a titanium-oxo cluster. A ferrocenecarboxylate-substituted titanium-oxo cluster [Ti6(µ3-O)6(OiPr)6(O2CFc)6] (Fc = ferrocenyl) was synthesized and structurally characterized, in which the ferrocene wheel performs as a sensitizer for photocurrent response. For comparison, naphthalene-sensitized titanium-oxo clusters [Ti6(µ3-O)6(OiPr)6(NA)6] (NA = 1-naphthoate) and [Ti6(µ3-O)6(OiPr)6(NAA)6] (NAA = 1-naphthylacetate) with the same {Ti6} core structure were also synthesized. The structures, optical behaviors, electronic states and photoelectrochemical properties of these sensitized {Ti6} clusters were investigated. It is demonstrated that the introduction of ferrocene groups into the titanium-oxo cluster significantly reduces the band gap and enhances the photocurrent response in comparison with the naphthalene-sensitized clusters. The substantially reduced band gap of the ferrocene-sensitized cluster was attributed to the introduction of Fe(ii) d-d transitions and the possible contribution from the Fc → {Ti6} charge transfer. For the naphthalene-sensitized clusters, the better electronic coupling between the dye and the {Ti6} core in the 1-naphthoate (NA) substituted cluster results in higher photoelectrochemical activity.

General Strategy for Controlled Synthesis of NixPy/Carbon and Its Evaluation as a Counter Electrode Material in Dye-Sensitized Solar Cells.

Hydrothermal treatment of nickel acetate and phosphoric acid aqueous solution followed with a carbothermal reduction assisted phosphorization process using sucrose as the carbon source for the controlled synthesis of NixPy/C was successfully realized for the first time. The critical synthesis factors, including reduction temperature, phosphorus/nickel ratio, pH, and sucrose amount were systematically investigated. Remarkably, the carbon serves as a reducer and plays a determinative role in the transformation of Ni2P2O7 into Ni2P/C. The synthesis strategy is divided into four distinguishable stages: (1) hydrothermal preparation of Ni3(PO4)2·8H2O precursor for stabilizing P sources; (2) dimerization of Ni3(PO4)2·8H2O into more thermal stable Ni2P2O7 amorphous phase along with the generation of NiO; (3) carbothermal reduction and phosphidation of NiO into NixPy (0 ≤ y/x ≤ 0.5); and (4) further phosphidation of mixed-phase NixPy and carbothermal reduction of Ni2P2O7 into single-phase Ni2P. The resultant Ni2P, the highly active phase in electrocatalysis, was applied as counter electrode in a dye-sensitized solar cell (DSSC). The DSSC based on Ni2P with 10.4 wt.% carbon delivers a power conversion efficiency of 9.57%, superior to that of state-of-the-art Pt-based cell (8.12%). The abundant Niδ+ and Pδ- active sites and the metal-like conductivity account for its outstanding catalytic performance.

Synthesis, Structure, Band Gap, and Near-Infrared Photosensitivity of a New Chalcogenide Crystal, (NH4)4Ag12Sn7Se22.

A new chalcogenide crystal, (NH4)4Ag12Sn7Se22 (FJSM-STS), has been solvothermally synthesized. The crystal structure, which is composed of arrays of [Sn3Se9]n(6n-) chains interconnecting [SnAg6Se10]n(10n-) and [Ag3Se4]n(5n-) layers, is unprecedented among the reported A/Ag/Sn/Q (A = cation; Q = S, Se, and Te) compounds. Optical absorption together with theoretical calculations of the band structure indicate a direct band gap of 1.21 eV for FJSM-STS, which is close to the ideal band gap to maximize the photoconversion efficiency proposed by Shockley and Queisser. The toxic-metal-free crystal of FJSM-STS exhibits obvious photosensitivity in the near-infrared range. The variates of power and temperature on the photosensitivity have been studied.

Varied forms of lamellar [Sn3Se7]n(2n-) anion: the competitive and synergistic structure-directing effects of metal-amine complex and imidazolium cations.

Presented are the syntheses, characterizations and properties of a series of selenidostannate compounds directed by metal-amine complex (MAC) cations and/or [Bmmim](+) (Bmmim = 1-butyl-2,3-dimethylimidazolium). Mixtures of the ionic liquid (IL) (Bmmim)Cl and amines, such as ethylenediamine (en) and diethylenetriamine (dien), in various ratios were used to ionothermally/solvothermally prepare four selenidostannates, namely, [Mn(en)3]Sn3Se7 (1), [Mn(dien)2]Sn3Se7·H2O (2), (Bmmim)3[Mn(en)3]2[Sn9Se21]Cl (3) and (Bmmim)6[Mn(dien)2]2Sn15Se35 (4). Single-crystal X-ray diffraction analyses revealed that these compounds exhibit lamellar anionic [Sn3Se7]n(2n-) structures. [Sn3Se7]n(2n-) layers in all 1-4 possess a {6(3)} net, considering [Sn3Se10] semi-cube unit as a 3-connected node; however, diverse multi-membered rings exist there. In compounds 1 and 2, all the [Sn3Se10] units are 3-connected nodes interlinking with each other via edge-sharing two Se atoms to produce six-membered rings. However, in compound 3, the insertion of two [Sn3Se9] units into a six-membered ring results in a novel eight-membered heart-shaped ring, which has never been observed before in the family of chalcogenidostannates. More interestingly, the [Sn3Se7]n(2n-) layer in compound 4 consists of mixed six- and eight-membered rings. The phase composition is strongly dependent on the ratio of IL to MAC in the syntheses, e.g., 1 and 2 were obtained with IL:MAC ratios less than 3:1 and 4:1, while 3 and 4 were obtained when the ratios were increased to 4:1 and 5:1, respectively. The structural variation from 1 to 4 clearly indicates the competitive and synergistic effects between MAC and IL cation on the formation of lamellar selenidostannates. A synthetic approach via varying the ratio of IL to MAC cation as solvent and structure-directing agent will be attractive in the synthesis of novel chalcogenidometallates.

[Bmim]2SbCl5: a main group metal-containing ionic liquid exhibiting tunable photoluminescence and white-light emission.

An antimony-based photoluminescent ionic liquid, namely [Bmim]2SbCl5, has been synthesized and characterized. It exhibits bright yellow and white light emission, with quantum yield as high as 86.3% under UV irradiation.

Syntheses, structures and photocatalytic properties of five new praseodymium-antimony oxochlorides: from discrete clusters to 3D inorganic-organic hybrid racemic compounds.

Five novel praseodymium-antimony oxochloride (Pr-Sb-O-Cl) cluster-based compounds, namely (2-MepyH)2[Fe(1,10-phen)3]2[Pr4Sb12O18Cl14.6(OH)2.4(Hsal)]·H2O (1), (2-MepyH)2[Fe(1,10-phen)3]4{[Pr4Sb12O18Cl13.5(OH)0.5](bcpb)2[Pr4Sb12O18Cl13.5(OH)0.5]}·42H2O (2), (3-MepyH)2[Fe(1,10-phen)3]{[Pr4Sb12O18Cl13(H2O)2](bcpb)}·2(3-Mepy)·3H2O (3), [Fe(1,10-phen)3]2{[Pr4Sb12O18Cl10(H2O)2](bcpb)2}·3(3-Mepy)·13H2O (4), and (2-MepyH)6[Fe(1,10-phen)3]10{[Pr4Sb12O18Cl13(OH)2]2[Pr4Sb12O18Cl9][Pr4Sb12O18Cl9(OH)2]2(Hpdc)10(pdc)2}·110H2O (5) (2-Mepy = 2-methylpyridine, 3-Mepy = 3-methylpyridine, 1,10-phen = 1,10-phenanthroline, H2sal = salicylic acid, H3bcpb = 3,5-bis(4-carboxyphenoxy)benzoic acid, H3pdc = 3,5-pyrazoledicarboxylic acid) have been solvothermally synthesized and structurally characterized. Compound 1 is the first zero-dimensional (0D) Pr-Sb-O-Cl cluster decorated by an organic ligand. Compounds 2-4 are constructed from the same H3bcpb ligands but adopt different structures: 2 represents a rare example of a one-dimensional (1D) nanotubular structure based on high-nuclearity clusters; 3 exhibits a two-dimensional (2D) mono-layered structure, in which left-handed and right-handed helical chains are alternately arranged, while 4 features a double-layered structure with an unprecedented (3,3,6)-connected 3-nodal topological net. Compound 5 is a unique three-dimensional (3D) 2-fold interpenetrating racemic compound, simultaneously containing three kinds of Pr-Sb-O-Cl-pdc clusters. UV-light photocatalytic H2 evolution activity was observed for compound 3 with Pt as a co-catalyst and MeOH as a sacrificial electron donor. In addition, the magnetic properties of compounds 1 and 5 are also studied.