Crystal structures of two novel iron isocyanides from the reaction of 2,6-dimethylphenyl isocyanide, CNXyl, with bis(anthracene)ferrate(−1)

The reaction of the [K(18-crown-6)(thf)2]1+ (thf is tetrahydrofuran) salt of bis(anthracene)ferrate(−1), or [Fe(C14H10)2]−, with 2,6-dimethylphenyl isocyanide (CNXyl) in thf resulted in the formation of two new iron isocyanide complexes, namely, [(1,2,3,4-η)-anthracene]tris(2,6-dimethylphenyl isocyanide)iron, [Fe(C14H10)(C9H9N)3] or [Fe(1,2,3,4-η-C14H10)(CNXyl)3], and {5,6-bis(2,6-dimethylanilino)-3-(2,6-dimethylphenyl)-1,2,7-tris[(2,6-dimethylphenyl)imino]-3-azoniahept-3-ene-1,4,7-triido}tris(2,6-dimethylphenyl isocyanide)iron tetrahydrofuran disolvate, [Fe(C54H56N6)(C9H9N)3]·2C4H8O or [Fe(C54H56N6)(CNXyl)3]·2C4H8O, which were characterized by single-crystal X-ray diffraction. The former is likely an intermediate along the path to the known homoleptic [Fe(CNXyl)5], while the latter contains a tridentate ligand that is formed from the `coupling' of six CNXyl ligands. A third crystal structure from this reaction, (7-methylindol-1-ido-κN)(1,4,7,10,13,16-hexaoxacyclooctadecane-κ6 O)potassium, [K(C9H8N)(C12H24O6)] or [K(C9H8N)(18-crown-6)], contains a 7-methylindol-1-ide anion, in which one CNXyl ligand has shed a proton during its reductive cyclization.

Syntheses, Characterization, and X-ray Crystal Structure of Binuclear Lanthanide Complexes Assembled with Schiff Base and Acetate

Herein we reported the binuclear complexes of the 1-(pyridin-2-yl)-2-(pyridin-2-ylmethylene)hydrazine ligand (HL) [Ln2(HL)2(CH3COO)6].n(H2O) (Ln = Y, Pr, Gd and Er). The binuclear complexes are characterized by IR and physical measurement. Spectroscopic evidence indicated that the Schiff base HL behave an N3 coordination tridentate ligand. The complexes are formulated as [{Ln(1-(pyridin-2-ylmethylidene-kN)-2-(pyridin-2-yl-kN)hydrazine-kN1)(h2-OOCH3)2}{h1:h2:m2-OOCH3}2{Ln(1-(pyridin-2-ylmethylidene-kN)-2-(pyridin-2-yl-kN)hydrazine-kN1))(h2-OOCH3)2}].n(H2O). The structure of the praseodymium complex was elucidated by X-ray diffraction analysis. Suitable crystals were grown by slow evaporation of methanol solution. The asymmetric unit of the compound contains two neutral ligand molecules, two Pr3+ ions, four acetate anions acting in h2-OOCH3 mode, two acetate anions acting in h1:h2:m2-OOCH3 mode, and three uncoordinated water molecules. The praseodymium atom is ten coordinated and the coordination sphere is best described as a distorted bicapped square antiprism. The PrIII···PrIII distance is 4.2777(6) Å and the bridging angle Pr—O—Pr and O—Pr—O are respectively 115.8(3)° and 64.2(3)°. The structure is consolidated by intra and intermolecular hydrogen bond.

Exploiting the Chiral Ligands of Bis(imidazolinyl)- and Bis(oxazolinyl)thiophenes—Synthesis and Application in Cu-Catalyzed Friedel–Crafts Asymmetric Alkylation

Five new C2-symmetric chiral ligands of 2,5-bis(imidazolinyl)thiophene (L1–L3) and 2,5-bis(oxazolinyl)thiophene (L4 and L5) were synthesized from thiophene-2,5-dicarboxylic acid (1) with enantiopure amino alcohols (4a–c) in excellent optical purity and chemical yield. The utility of these new chiral ligands for Friedel–Crafts asymmetric alkylation was explored. Subsequently, the optimized tridentate ligand L5 and Cu(OTf)2 catalyst (15 mol%) in toluene for 48 h promoted Friedel–Crafts asymmetric alkylation in moderate to good yields (up to 76%) and with good enantioselectivity (up to 81% ee). The bis(oxazolinyl)thiophene ligands were more potent than bis(imidazolinyl)thiophene analogues for the asymmetric induction of the Friedel–Crafts asymmetric alkylation.

A Novel L-Shaped Fluorescent Probe for AIE Sensing of Zinc (II) Ion by a DR/NIR Response

In the field of optical sensors, small molecules responsive to metal cations are of current interest. Probes displaying aggregation-induced emission (AIE) can solve the problems due to the aggregation-caused quenching (ACQ) molecules, scarcely emissive as aggregates in aqueous media and in tissues. The addition of a metal cation to an AIE ligand dissolved in solution can cause a “turn-on” of the fluorescence emission. Half-cruciform-shaped molecules can be a winning strategy to build specific AIE probes. Herein, we report the synthesis and characterization of a novel L-shaped fluorophore containing a benzofuran core condensed with 3-hydroxy-2-naphthaldehyde crossed with a nitrobenzene moiety. The novel AIE probe produces a fast colorimetric and fluorescence response toward zinc (II) in both in neutral and basic conditions. Acting as a tridentate ligand, it produces a complex with enhanced and red-shifted emission in the DR/NIR spectral range. The AIE nature of both compounds was examined on the basis of X-ray crystallography and DFT analysis.

Mononuclear and Tetranuclear Copper(II) Complexes Bearing Amino Acid Schiff Base Ligands: Structural Characterization and Catalytic Applications

Two new glycine-Schiff base copper(II) complexes were synthesized. Single crystal X-ray diffraction (SCXRD) allowed us to establish the structure of both complexes in the solid state. The glycine-Schiff base copper(II) complex derived from 2′-hydroxy-5′-nitroacetophenone showed a mononuclear hydrated structure, in which the Schiff base acted as a tridentate ligand, and the glycine-Schiff base copper(II) complex derived from 2′-hydroxy-5′-methylacetophenone showed a less common tetranuclear anhydrous metallocyclic structure, in which the Schiff base acted as a tetradentate ligand. In both compounds, copper(II) had a tetracoordinated square planar geometry. The results of vibrational, electronic, and paramagnetic spectroscopies, as well as thermal analysis, were consistent with the crystal structures. Both complexes were evaluated as catalysts in the olefin cyclopropanation by carbene transference, and both led to very high diastereoselectivity (greater than 98%).

The Synthesis and Properties of TIPA-Dominated Porous Metal-Organic Frameworks

Metal-Organic Frameworks (MOFs) as a class of crystalline materials are constructed using metal nodes and organic spacers. Polydentate N-donor ligands play a mainstay-type role in the construction of metal−organic frameworks, especially cationic MOFs. Highly stable cationic MOFs with high porosity and open channels exhibit distinct advantages, they can act as a powerful ion exchange platform for the capture of toxic heavy-metal oxoanions through a Single-Crystal to Single-Crystal (SC-SC) pattern. Porous luminescent MOFs can act as nano-sized containers to encapsulate guest emitters and construct multi-emitter materials for chemical sensing. This feature article reviews the synthesis and application of porous Metal-Organic Frameworks based on tridentate ligand tris (4-(1H-imidazol-1-yl) phenyl) amine (TIPA) and focuses on design strategies for the synthesis of TIPA-dominated Metal-Organic Frameworks with high porosity and stability. The design strategies are integrated into four types: small organic molecule as auxiliaries, inorganic oxyanion as auxiliaries, small organic molecule as secondary linkers, and metal clusters as nodes. The applications of ratiometric sensing, the adsorption of oxyanions contaminants from water, and small molecule gas storage are summarized. We hope to provide experience and inspiration in the design and construction of highly porous MOFs base on polydentate N-donor ligands.

Three-Dimensional Walnut-Like, Hierarchically Zn-MOF Microsphere: One-Pot Synthesis, Characterization And Its Application as a Green Catalyst For The Asymmetric Hantzsch Synthesis of Polyhydroquinolines

A three-dimensional walnut-like, microsphere Zn-based MOFs system was designed and synthesized via hydrothermal reaction of zinc salt with 4,6-diamino-2-pyrimidinethiol as a tridentate ligand. Besides, Zn ions were coordinated to the ligand’s functional groups to give a novel Zn-MOF microsphere material. Afterward, the resultant material was thoroughly characterized by various analysis and physico-chemical methods; including, FT-IR, XRD, TGA, EDX, X-ray mapping, SEM, TEM, and BET analysis. The Zn-MOF microspheres were utilized in the Hantzsch reaction for selective synthesis of asymmetric polyhydroquinolines, using various aromatic aldehydes. Our strategy provides a way for controlled synthesis of the hierarchically nanoporous Zn-MOF microspheres with well-defined morphology, structure, and excellent catalytic properties, resulting in having a promising heterogeneous catalyst for a selective synthesis with good yields in the short reaction time and a low limit of steric hindrance and electronic effects. Besides, the heterogeneity of the catalyst is further tested with hot filtration and also the reusability results point.