Search

Polymorphism control of metal-organic frameworks is highly desired for elucidating structure-property relationships, but remains an empirical process and is usually done in a trial-and-error approach. We adopted the rarely used actinide cation Th4+ and a ditopic linker to construct a series of thorium-organic frameworks (TOFs) with a range of polymorphs. The extraordinary coordination versatility of Th4+ cations and clusters, coupled with synthetic modulation, gives five distinct phases, wherein the highest degree of interpenetration (threefold) and porosity (75.9 %) of TOFs have been achieved. Notably, the O atom on the capping site of the nine-coordinated Th4+ cation can function as a bridging unit to interconnect neighboring secondary building units (SBUs), affording topologies that are undocumented for other tetravalent-metal-containing MOFs. Furthermore, for the first time HCOOH has been demonstrated as a bridging unit of SBUs to further induce structural complexity. The resulting TOFs exhibit considerably different adsorption behaviors toward organic dyes, thus suggesting that TOFs represent an exceptional and promising platform for structure-property relationship study.

A RhIII -catalysed three-component synthesis of isoindolinone frameworks via direct assembly of benzoyl chlorides, o-aminophenols and activated alkenes has been developed. The process involves in situ generation of o-aminophenol (OAP)-based bidentate directing group (DG), RhIII -catalysed tandem ortho C-H olefination and subsequent cyclization via aza-Michael addition. This protocol exhibits good chemoselectivity and functional group tolerance. Computational studies showed that the presence of hydroxyl group on the N-aryl ring could enhance the chemoselectivity of the reaction.

A simple and regioselective palladium-catalyzed ortho-C(sp2)–H acetoxylation of 2-aryloxypyridines with PhI(OAc)2 as both the oxidant and acetate source has been developed. The mono- and di-acetoxylated products can be achieved by tuning the equivalents of PhI(OAc)2 and the reaction temperature. A wide range of 2-aryloxypyridines is tolerated. Moreover, 2-pyridyloxyl and acetyl groups can be easily removed, which provides straightforward access to poly-substituted phenols.

Two bismuth(III) complexes {[Bi(btx)0.5Cl4](Hbtx)}n (1) and [Bi2(Fbtx)Cl10](H2Fbtx)2(MeOH) (2) based on the nonfluorinated ligand 1,4-bis[(1,2,4-triazole-1-yl)methyl] benzene (btx) or the perfluorinated analogue 1,4-bis[(1,2,4-triazole-1-yl)methyl]-2,3,5,6-benzene (Fbtx) were synthesized and characterized. Single-crystal X-ray diffraction revealed that 1 is a coordination polymer consisting of an anionic one-dimensional chain, whereas 2 shows a discrete ionic-paired structure. Furthermore, 1 was found to be more active than 2 toward the bulk solvent-free polymerization of glycolide, giving poly(glycolic acid) (PGA) with high molecular weights and moderate molecular weight distributions. The results indicated that the substituent effect plays an important role in controlling the structure and catalytic activity of such complexes.

The coordination polymers {[Cd(o-BDC-Cl4)(H2O)2]·EtOH}n (1) and {[Cd(p-BDC-Cl4)(DMF)]·H2O}n (2) (o-BDC-Cl4 = tetrachlorophthalate and p-BDC-Cl4 = tetrachloroterephthalate) were synthesized in different solvents using two isomeric tetrachlorinated benzenedicarboxylic acids. Complex 1 based on o-BDC-Cl4 features an extremely rare 2D trinodal (3,4,6)-connected network constructed by the combination of 1D [Cd-H2O]n chains and 1D [Cd2(o-BDC-Cl4)2]n loop-like motifs. Complex 2 based on p-BDC-Cl4 has a 3D framework and shows a uninodal 4-connected sra topology. Complexes 1 and 2 were characterized by elemental analyses, IR spectroscopy, single-crystal X-ray diffraction and thermogravimetric (TG) analyses. The photoluminescence of 1 and 2 were investigated in the solid state at room temperature.

A Rhodium(III)-catalyzed ortho-C-H olefination of aromatic aldehydes in the presence of catalytic amount of TsNH2 has been developed. The in situ generated imine intermediate from aldehyde and TsNH2 worked as a transient directing group. Both electron-rich and electron-deficient aromatic aldehydes were tolerated, affording the corresponding products in moderate to good yields. Importantly, the present protocol provides a straightforward access to olefinated aromatic aldehydes with aldehydes as the simple starting materials.

On the basis of the mechanism of Baeyer–Villiger (B-V) oxidation, a bifunctional catalyst based on tetra(4-sulfonato-phenyl)porphinato-cobalt(II) anion (CoTSPP) intercalated into Zn2Al hydrotalcite (Zn2Al-LDH; LDH=layered double hydroxide) was designed and prepared. XRD, FTIR, DR UV/vis, TG/DTA, and SEM characterization indicate that CoTSPP molecular has been successfully intercalated into the layers of Zn2Al-LDH. The catalytic activity of the synthesized hybrid in the B-V oxidation for various ketones is excellent. Control experiments indicated that the catalyst has a bifunctional role in the reactions. The protocol opens up new perspectives in the rational design of efficient catalytic systems.

Aromatic nitriles were synthesized through copper-catalyzed cyanations of aromatic bromides using benzoyl cyanide as the cyanide source. A series of functional groups were tolerated under the reaction conditions to provide the products in good yields. Moreover, this protocol avoids using of highly toxic alkali cyanides and expensive palladium catalysts.

Reaction of the rigid ligand 2,4,5,6-tetrachloro-1,3-benzenedicarboxylic acid (1,3-H2BDC-Cl4) with copper(II) nitrate in different solvent systems afforded two new complexes {[Cu(1,3-BDC-Cl4)(DMF)] (H2O)}n (1) and {[Cu(1,3-BDC-Cl4)(H2O)3] (dioxane)·(H2O)}n (2), which were fully characterized by elemental analysis, IR spectroscopy, as well as single crystal and powder X-ray diffiraction techniques. Single-crystal X-ray diffraction reveals that complexes 1 and 2 crystallize in different space groups P21/m and Pbca, respectivly. Compound 1 shows a two-dimensional (2D) (4,6)-connected layered network constructed by the connectivity between one-dimensional (1D) [–Cu–DMF–COO–]n chains and tetrachlorinated backbones of 1,3-BDC-Cl4, which is further assembled to generate a three-dimensional (3D) supramolecular framework through intermolecular O–H···O and O–H···Cl hydrogen-bonding interactions. Compound 2 features a 2D 4-connected sql coordination net formed by 1D [Cu-H2O]n chains and 1,3-BDC-Cl4 spacers, which is further extended into a 3D supramolecular network by multiple O–H···O hydrogen-bonding interactions. The different structural features of the two compounds suggest that the choice of solvent systems should play a key role in the process of assembly. Their thermal and fluorescence properties were also investigated.

A simple and efficient synthesis of fluorine-containing heterocycles via SNAr reaction of tetrafluoroterephthalonitrile with various nucleophiles assisted by ultrasound has been developed. The reaction proceeded smoothly at room temperature within 5 min to afford mono-substituted heterocycles in moderate to good yields.

A silver(I) coordination polymer with mixed 2,3,5,6-tetrachloro-1,4-benzenedicarboxylate (BDC-Cl4) and 2,2′-bipyridine (2,2′-bpy) ligands, [Ag2(BDC-Cl4)(2,2′-bpy)]n (1), was synthesized and structurally characterized. Compound 1 features a robust three-dimensional (3D) network, exhibiting a new (4,6)-connected net with the Schlafli symbol of (32·42·5·6)2(32·42·52·87·9·10). The photoluminescence properties of 1 were investigated in the solid state at room temperature.

Yields of mono- as well as bis-acetoxylated arenes depend significantly on the electronic nature of aryl substituents.

TiO 2 /MoS 2 nanocomposite photocatalyst was prepared via simple one-step hydrothermal process. This nontoxic and inexpensive photocatalyst exhibited high activity toward the thiocyanation of indoles under visible light irradiation at room temperature. Simple work-up, good yields, as well as reusability of the catalyst are the major advantages of the present method.

A palladium-catalyzed, one-pot synthesis of unsymmetrical aryl alkyl thioethers involving aryl halides (aryl bromides and chlorides), thiourea and alkyl bromides has been realized under mild conditions (room temperature to 50 °C) in water with polyoxyethanyl α-tocopheryl sebacate (PTS) as amphiphile. The PTS/water could be recycled in up to eight runs without an obvious change in its activity.

Two new coordination polymers [Cd(1,2-BDC-F4)(H2O)2(py)]n (1) and {[Cd(1,2-BDC-F4)(H2O)2](DMF)}n (2) were prepared from the vapor diffusion reactions of CdII acetate with tetrafluorophthalic acid (1,2-H2BDC-F4) under different solvent atmospheres, and structurally characterized by single-crystal diffraction technique. Both complexes reveal polymeric coordination architectures. Complex 1 is a one-dimensional (1D) double chain, which crystallizes in the space group, P212121. In 1, each CdII ion is hexacoordinate by five oxygen atoms from two terminal water and three 1,2-BDC-F4 anions with a μ3-bridging mode, as well as one nitrogen donor from one pyridine molecule. Complex 2 is a two-dimensional (2D) layered network, which crystallizes in the P\bar{1} space group. In 2, each CdII ion is heptacoordinate by seven oxygen atoms from two terminal water and four 1,2-BDC-F4 anions with a μ4-bridging mode. The results clearly suggest that the judicious choice of solvent systems does play a critical role in the construction of coordination frameworks with distinct dimensionality and connectivity. Their spectroscopic, thermal, and fluorescence properties have also been investigated.

The reactions of cobalt acetates with tetrachloroterephthalic acid (H2BDC-Cl4) in different solvents gave two polymeric and one mononuclear CoII complexes. X-ray single-crystal structural determination revealed that the ligand BDC-Cl4 displays a reliable bridging tecton to construct diverse supramolecular architectures through coordinative bonds or secondary hydrogen-bonding interactions. The complexes [Co(BDC-Cl4)(DMF)2(EtOH)2]n (1) and {[Co(BDC-Cl4)(DMF)2(MeOH)2]·2DMF}n (2) demonstrate a one-dimensional (1D) coordination motif with infinite CoII-tetrachloroterephthalate chains, which are tuned by different binding solvent systems of DMF/ethanol (EtOH) and DMF/methanol (MeOH). [Co(DMF)2(H2O)4]·(BDC-Cl4) (3) represents a two-dimensional (2D) metallosupramolecular network by hydrogen-bonded bridging between the aqua ligand of the mononuclear complex with the uncoordinated BDC-Cl4 solvates. The spectroscopic, thermal, and fluorescent properties of 1–3 were also investigated.

The title reaction proceeds under optimized conditions to afford the corresponding hemiaminal derivatives in moderate to good yields.

A metal- and base-free protocol for one-pot synthesis of 2,5-diaryl 1,3,4-oxadiazoles via a radical-promoted cross-dehydrogenative coupling strategy was developed. This reaction involved the N-acylation of aryl tetrazoles with aryl aldehydes, followed by thermal rearrangement. A wide range of aryl tetrazoles and aryl aldehydes survived the reaction conditions to deliver the corresponding products in moderate to good yields.

The catalyst promotes both the oxidation of benzaldehyde to the corresponding percarboxylic acid and the conversion of cyclic ketones into lactones.

Aromatic nitriles were synthesized through copper-catalyzed cyanations of aromatic bromides using benzoyl cyanide as the cyanide source. A series of functional groups were tolerated under the reaction conditions to provide the products in good yields. Moreover, this protocol avoids using of highly toxic alkali cyanides and expensive palladium catalysts.

A transition-metal-free synthetic approach for constructing alkylated aryl tetrazoles has been developed using n-Bu4NI as the catalyst and t-BuOOH as the oxidant. It involves the direct C–N bond formation through sp3 C–H activation. A wide range of benzylic C–H substrates (or alkyl ethers) and aryl tetrazoles undergo this reaction smoothly to deliver the corresponding products in good yields.

The oxidative coupling of methylarenes with thiols tolerates various functional groups in both partners and gives thioesters in moderate to good yields.

A straightforward route for the synthesis of o-alkenylaryl tetrazoles via Rh-catalyzed C—H olefination of aryl tetrazoles is described.

The reaction of various bis-nucleophiles with tetrafluoroterephthalonitrile (I) is studied.

A kind of Metal–organic framework (MOF) composite namely Cu-BTC@Fe3O4 (BTC = 1,3,5-benzenetricarboxylate) was prepared and showed good catalytic activity toward the reduction of nitroarenes. This reaction proceeded smoothly under mild reaction conditions in aqueous medium using sodium borohydride as the reduction agent, affording the corresponding anilines in good to excellent yields. In addition, the catalyst could be easily recovered with an external permanent magnet and be reused for successive six runs with slight decrease in its activity.

An orthogonal dimeric BODIPY was easily prepared via condensation of 2,4-dimethylpyrrole and oxalyl dichloride, and was utilized as a visible-light-driven photocatalyst for the oxidation of sulfides. High catalytic efficiencies, and mild and green conditions are the major advantages of this protocol. Moreover, meso-carbalkoxylated BODIPYs could also be prepared using a similar one-pot condensation of 2,4-dimethylpyrrole, oxalyl dichloride and a series of alcohols.

Major advantages of the introduced protocol are broad substrate compatibility, good yields and selectivities, the reusability of the catalyst as well as the possibility of gram-scale synthesis.

The deep eutectic solvent catalyst is non-toxic, inexpensive and easily recyclable and can be reused for at least five times without considerable loss of its effectivity.

A new deep eutectic mixture based on choline chloride and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) was prepared and was found to be effective for the rapid transformation of aryl/heteroaryl boronic acids to the corresponding phenols in water using hydrogen peroxide as the oxidant. Broad substrate compatibility, metal- and additive-free conditions as well as reusability of the catalyst made this procedure more environmentally benign.

The Broensted acidic deep eutectic solvent based on choline chloride and TosOH is found to be an effective catalyst for the one-pot, multicomponent synthesis of polysubstituted imidazoles.

The super acidic ionic liquid Me—C(OH)2+ClO4-, prepared by mixing acetic acid and perchloride acid at room temperature, is shown to be an extremely active catalyst for the synthesis of dihydropyrimidine derivatives via Biginelli-type reactions.

An efficient and selective conversion of various aldehydes into corresponding nitriles and primary amides using tBuOOH and aqueous ammonia is presented.

Three new coordination compounds, [Pb(HBDC-I4)2(DMF)4](1) and [M(BDC-I4)(MeOH)2(DMF)2]n (M = ZnII for 2 and MnII for (3) (H2BDC-I4 = 2, 3, 5, 6-tetraiodo-1, 4-benzenedicarboxylic acid), were synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric (TG) analysis, and X-ray single crystal structure analysis. Single-crystal X-ray diffraction reveals that 1 crystallizes in the monoclinic space group C2/c and has a discrete mononuclear structure, which is further assembled to form a two-dimensional (2D) layer through intermolecular O–H···O and C–H···O hydrogen bonding interactions. The isostructural compounds 2 and 3 crystallize in the space group P21/c and have similar one-dimensional (1D) chain structures that are extended into three-dimensional (3D) supramolecular networks by interchain C–H···π interactions. The PbII and ZnII complexes 1 and 2 display similar emissions at 472 nm in the solid state, which essentially are intraligand transitions.

The title reaction of aryl chlorides or bromides with alkyl halides and thiourea as thiol surrogate proceeds at room temperature in many cases.