Synthesis and application of novel ionic phosphine ligands with a cobaltocenium backbone

Six novel ionic phosphine ligands with a cobaltocenium backbone, 1,1′-bis(dicyclohexylphosphino) cobaltocenium hexafluorophosphate () (1a), 1,1′-bis(di-iso-propylphosphino) cobaltocenium hexafluorophosphate () (2a), 1,1′-bis(di-tert-butylphosphino) cobaltocenium hexafluorophosphate () (3a), and the monophosphine ligand (Cc⁺ = cobaltocenium; R = Cy, 1b; R = i-Pr, 2b; R = t-Bu, 3b) were synthesized and characterized by elemental analysis, spectroscopy, and X-ray diffraction techniques. These ligands are air-stable and useful for Suzuki coupling reactions in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (), enabling high catalytic activity.     

Quaternary ammonium salt-based chromogenic and fluorescent chemosensors for fluoride ions

Chemosensors 5-7 possessing a quaternary ammonium cation (for electrostatic interactions) and an N-H group(s) (for H-bonding) as recognition sites and an anthracene-9,10-dione as both a chromogenic and fluorescent moiety exhibit absorption and emission changes with fluoride ions only. No significant response to other anions such as Cl⁻, Br⁻, I⁻, , CH₃COO⁻, , and is observed. The dual emission at λ_max 580 nm (free 5/6) and λ_max 510 and 540 nm (5/6 + F⁻) in chemosensors 5 and 6 enables ratiometric analysis of fluoride ions.     

Adamantane-dipyrromethanes: novel anion receptors

New adamantane-dipyrromethanes (AdD 1-4) were synthesized and their anion binding properties investigated. AdD 1-3 form 2:1 complexes with F⁻ (AdD:F = 2:1) characterized by high association constants, and 1:1 complexes with Cl⁻, Br⁻, and . The binding of Cl⁻, Br⁻, and by AdD 1-3 is 2-3 times stronger than for the reference compound, meso-phenyldipyrromethane (5). However, AdD 4 forms complexes with F⁻ characterized by 1:1 and 1:2 stoichiometry (AdD:F = 1:2).     

Structure characterization of 1:1 adducts of metal(II) halides and piperazine

From the simple hydro/solvothermal reactions, two 1:1 adducts of MX₂ and piperazine (pip) [CdI₂(pip)] 1 and [CoCl₂(pip)] 2 were prepared. Both were characterized by elemental analyses, IR spectra, ultra-violet visible spectra, thermogravimetric analyses and X-ray single-crystal diffraction. With pip as the bridges, the 1-D linear CdI₂ chains are extended into a 2-D layered compound 1, while the mononuclear CoCl₂ units are linked into a 1-D zigzag-type chain compound 2. The fluorescence emission spectrum indicates that compound 1 possesses fluorescence property with the peaks at 373 nm () and 410 nm ().     

Design and synthesis of four coordination polymers generated from 2,2′-biquinoline-4,4′-dicarboxylate and aromatic bidentate ligands

Four coordination polymers [Zn(bqdc)(phen)]_n (1), [Zn(bqdc)(bpy)(H₂O)]_n (2), [Mn(bqdc)(bpy)(H₂O)₂]_n (3) and [Mn(bqdc)(phen)(H₂O)₂]_n (4) (H₂bqdc=2,2′-biquinoline-4,4′-dicarboxylic acid, phen=1,10-phenanthroline and bpy=2,2′-bipyridyl) have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction. Crystal data for 1: monoclinic system, C2/c, , , , β=103.78(3)°, , Z=4. Crystal data for 2: monoclinic system, p2₁/n, , , , β=107.13(7)°, , Z=4. Crystal data for 3: monoclinic system, C2/c, , , , β=116.8010(11)°, , Z=4. Crystal data for 4: monoclinic system, C2/c, , , , β=117.04(3)°, , Z=4. Single helix-like chains exist in 1. The supramolecular structure of 1 exhibits extended two-dimensional network while 2-4 display extended three-dimensional architectures based on interchain hydrogen bonding and π-π interactions. Compounds 1 and 2 show blue photoluminescence under UV light suggesting that they may be employed to develop luminescent materials. Compounds 3 and 4 show interesting magnetic behaviors.     

An anionic chromogenic sensor based on the competition between the anion and a merocyanine solvatochromic dye for calix[4]pyrrole as a receptor site

The interaction of Brooker’s merocyanine (BM), a merocyanine dye, with calix[4]pyrrole (CP) was studied in acetonitrile. BM is violet in solution, but its interaction with CP changes the color of the solution due to the formation of CP-BM species associated through hydrogen bonding. A displacement assay was then carried out in the presence of different anions (F⁻, Cl⁻, Br⁻, I⁻, , , and ). It was verified that F⁻, and to a lesser extent Cl⁻ and , displace BM through the formation of a complex with CP, coloring the solution. Addition of makes the solution almost colorless because it is sufficiently acidic to transfer a proton to BM, removing it from the receptor site in CP and protonating the dye, thereby allowing the visual detection of the anion in relation to the other anions.     

Synthesis and characterization of new, modified terphenyl ligands: Increasing the rotational barrier for flanking rings

The synthesis and characterization of some new terphenyl ligands, modified by meta alkyl substitution on the central ring are described. The new ligands were designed for potential applications in the stabilization of novel low valent main group species or transition metal heteronuclear multiply bonded compounds. Compounds (1), (3) (Mes = 2,4,6-trimethylphenyl), (5) (Trip = 2,4,6-triisopropylphenyl) and (6) (Dipp = 2,6-diisopropylphenyl) were obtained by addition of two equivalents of the corresponding aryl Grignard reagent to the benzyne intermediate generated by lithiation with BuⁿLi of the starting material 2,4-dichloro-5-isopropylcumene, followed by quenching with iodine. The lithium salts of 2 and 4 were obtained treatment of the parent terphenyl iodides with one equivalent of nBuLi. All compounds were isolated as either colorless crystals or as white powders. They were characterized by ¹H and ¹³C NMR spectroscopy and (in the case of 1 and 3) by X-ray crystallography. DFT calculations were performed on model terphenyl molecules in an attempt to estimate how much the rotation barriers of the flanking aryls can be influenced by substitution by alkyl groups of the two meta positions on central ring.     

Reactions of pyridyl donors with halogens and interhalogens: an X-ray diffraction and FT-Raman investigation

Three different N-donors L, namely N-ethyl-N′-3-pyridyl-imidazolidine-4,5-dione-2-thione (1), N,N′-bis(3-pyridylmethyl)-imidazolidine-4,5-dione-2-thione (2), and tetra-2-pyridyl-pyrazine (3), bearing one, two and four pyridyl substituents, respectively, have been reacted with halogens X₂ (X = Br, I) or interhalogens XY (X = I; Y = Cl, Br). CT σ-adducts L · nXY, bearing linear N?XY moieties (L = 3; X = I; Y = Br, I; n = 2), and salts containing the protonated cationic donors H_nLⁿ⁺ (L = 1 − 3; n = 1, 2, 4), counterbalanced by Cl⁻, Br⁻, , , , , I₂Br⁻, , or anions, have been isolated. Among the reactions products, (H1⁺)Cl⁻, (H1⁺)Br⁻, , , and 3 · 2IBr have been characterised by single-crystal X-ray diffraction. The nature of the products has been elucidated based on elemental analysis and FT-Raman spectroscopy supported by MP2 and DFT calculations.     

A new fluorescent metal sensor with two binding moieties

A new fluorescent chelator Oxa, having two metal-binding sites, was designed and synthesized in six steps. Oxa exhibited two distinctive dissociation constants for Zn²⁺ ( μM and  μM), with considerable fluorescence increase in aqueous buffer at pH 7.2. Affinities of Oxa for the other biologically important ions such as Ca²⁺ ( μM and  mM) and Mg²⁺ ( μM and could not be determined) in the same conditions were also obtained.     

Synthesis, structure and optical limiting effect of a novel inorganic-organic hybrid polymer containing mixed chains of copper(I)/iodine

In this paper, treatment of N-ethyl-benzo[f]quinolium (ebq) iodide and CuI with excess KI afforded an unusual coordination polymer [(ebq)₂(Cu₃I₄)(CuI₂)]_n (1). 1 crystallizes in tetragonal system, space group P4(2)bc with cell parameters of , , , Z=8, , R₁=0.0447 and wR₂=0.0974. A highly interesting feature of 1 is its presence of mixed types of chains [ and chain] in one crystal lattice based on supramolecular self-assembly directed by cations. The infinite chains and in 1 could be described as the edge-sharing arrangement of CuI₄ tetrahedron. Furthermore, IR, EA, UV-Vis, thermal analysis and optical limiting measurements were adopted to characterize polymer 1. The optical limiting experiment shows that the present polymer exhibits a large optical limiting capacity.     

Low-temperature flux syntheses and characterizations of two 1-D anhydrous borophosphates: Na3B6PO13 and Na3BP2O8

Two new anhydrous sodium borophosphates with one-dimensional structure, Na₃B₆PO₁₃(1) and Na₃BP₂O₈(2), were synthesized by low-temperature molten salts techniques using boric acid and sodium dihydrogen phosphate as flux, respectively. The crystal structures were solved by means of single-crystal X-ray diffraction (1, orthorhombic, Pnma (no. 62), , , , Z=4; 2 , monoclinic, C2/c (no. 15), , , , β=92.492(5)°, Z=8). Compound 1 is characterized by an infinite chain of containing eight-membered rings in which all vertexes of borate groups contribute to interconnection. Compound 2 reveals an infinite straight chain built of vertex-sharing four-membered rings, and chains in neighboring layers arranged along different orientations. The relations between structures and the synthetic conditions with only traced water are discussed.     

Self-assembly of silver polymers based on flexible isonicotinate ligand at different pH values: syntheses, structures and photoluminescent properties

Two interesting coordination polymers, [Ag₈(IN)₆(NO₃)₂] 1 and [Ag(IN)(HIN)]_1/2 [Ag(IN)] 2 (HIN=isonicotinic acid) have been synthesized hydrothermally at different pH values. 1 crystallizes in the triclinic space group P-1, with , , , α=75.87(3)°, β=80.87(3)°, γ=76.50(3)°, and Z=2. Compound 1 is the first example of a bilayer framework, in which both single layers are connected by the bond interactions (Ag-O) between Ag from two two-dimensional (2D) single layers generated by the A building block and O atoms from one-dimensional (1D) chain constructed by the B building block, in which coordination modes of IN were reported for the first time. 2 crystallizes in the monoclinic space group P2(1)/c, with , , , β=92.90(3)°, V=1185.0(4) and Z=4. Compound 2 exhibits a 2D plywood-like structure assembled by hydrogen bonds and weak Ag-O interactions.