Tomohito Ide

Tetrapalladium complex with bridging germylene ligands. Structural change of the planar Pd4Ge3 core.

A complex with a planar hexagonal Pd(4)Ge(3) core, [Pd{Pd(dmpe)}(3)(μ(3)-GePh(2))(3)], was synthesized and characterized by X-ray and NMR measurements as well as by DFT calculations. 4-tert-Butylbenzenethiol converted the Pd(4) complex into a hexapalladium complex, [{Pd(3)(μ-GePh(2))(2)(μ-H)(μ(3)-GePh(2)(SC(6)H(4)(t)Bu-4))}(2)(μ-dmpe)], composed of two Pd(3)Ge(3) units bridged by a dmpe ligand. The addition of CuI or AgI to the Pd(4) complex yielded [Pd(μ-MI){Pd(dmpe)}(3)(μ(3)-GePh(2))(3) ] (M = Cu, Ag), in which Cu or Ag bridges a Pd-Pd bond of the Pd(4)Ge(3) core. The CuI adducts in solution undergo a pivot motion of the CuI on the surface of the Pd(4)Ge(3) plane on the NMR time scale.

Dynamic Properties of Molecular Tweezers with a Bis(2‐hydroxyphenyl)pyrimidine Backbone

4,6-Bis(2-hydroxyphenyl)-2-alkylpyrimidines with two anthryl or 9-ethylnylanthryl substituents at the positions para to the OH groups prefer a U-shaped conformation supported by two intramolecular OH⋅⋅⋅N hydrogen bonds in the solid state and in CDCl3 solution. The compound with a hexyl substituent on the pyrimidine group and two 9-ethynylanthryl arms at the hydroxyphenyl groups forms a 1:1 complex with 2,4,7-trinitrofluorenone. Its association constant K(a) was estimated to be 2100 M(-1) at 298 K, which is larger than those of other molecular tweezers (K(a) < 1000 M(-1)). DFT calculations suggested that the complex adopts a stable conformation supported by intramolecular hydrogen bonds among the OH groups and the pyrimidine ring as well as by intermolecular π-π interaction between the anthryl groups and 2,4,7-trinitrofluorenone. Addition of nBu4NF to a solution of the molecular tweezers or their complexes causes the cleavage of one or two OH⋅⋅⋅N hydrogen bonds, formation of new O⋅⋅⋅HF hydrogen bonds, and changes in the molecular conformation. The resulting structure of the molecular tweezers contains nonparallel anthryl groups, which do not bind the guest molecule. Photochemical measurements on 4,6-bis(2-hydroxyphenyl)-2-methylpyrimidine with two anthryl substituents showed negligible luminescence (quantum yield ϕ<0.01), owing to photoinduced electron transfer of the molecule with a U-shaped structure. However, the O-hexylated compound exhibits emission from the anthryl groups with ϕ=0.39.

Evaluation of the flocculation and de-flocculation performance and mechanism of polymer flocculants

Understanding the interaction mechanism between polymeric flocculants and solid particles in two oppositely charged solutions: bentonite and calcium fluoride, is of great practical and fundamental importance. In this work, inorganic flocculants based on aluminum(III) or iron(III); cationic, anionic and non-ionic organic flocculants were used. The solution pH, which highly influenced the flocculation performance of the system, has been used as a function of turbidity removal, sediment volume and velocity. Results show that the flocculation of inorganic polymers does not depend on the zeta potential but on the solution pH, contrary for cationic and anionic polymers. Non-ionic polymer was independent on both. By varying the final pH of the heterogeneous solution formed of flocs-liquid, it was found for inorganic polymers, the optimum condition of pH < 3 to separate inorganic flocculant particles from flocs. Inductively coupled plasma atomic emission spectrometer and X-ray fluorescence analysis proved the reversibility of flocculation process by indicating the concentration of flocculant representative atom (Al or Fe) in the flocs and in the emerging solutions when the flocculation was optimized and the reversibility was effective. As results, weak forces were suggested as responsible for inorganic polymers flocculation where electrostatic interaction and hydrogen bonds may enroll the mechanism of organic flocculants.

Aromatic Macrocycle Containing Amine and Imine Groups: Intramolecular Charge-Transfer and Multiple Redox Behavior

A cyclic compound that has alternating diphenylamine and quinodiimine units was obtained by condensation of anthraquinone with bis(4-aminophenyl)amine (aniline dimer) in 20% yield. The resulting macrocycle has an absorption of 462 nm, which is assigned to charge transfer transitions between electron-rich diphenylamine units and electron-poor anthraquinone diimine units. Cyclic voltammetry in acidic MeCN shows redox of anthraquinone diimine units (E(1/2) = 0.03 V vs Ag/Ag(+)) and of oxidation of amino groups of higher potentials (0.60 and 0.77 V).

Strained and unstrained macrocycles composed of carbazole and butadiyne units: electronic state and optical properties.

Cu(OAc)(2) catalyzes dehydrogenative condensation of 3,6-bis(2-ethynylphenyl)carbazole in the presence of O(2) to afford the cyclization product 1 and cyclodimer 2. Compound 1 contains bent carbazole and butadiyne groups, while 2 has a less strained structure with Z shape around the two parallel butadiyne groups. Optical properties of the compounds are discussed based on the electronic states estimated from electrochemical measurement and density functional theory calculation.

Lanthanide selective adsorption by ion-imprinted polymer with chelidonic acid monoamide groups

ABSTRACT Lanthanide selective adsorbent with chelidonic acid monoamide group was synthesized based on the ion-imprint method and its adsorption character was investigated. A polymerizable ligand 3 with chelidonic acid group was obtained by condensation of chelidonic acid and 4-aminostyrene. A Nd-complex monomer 7 was synthesized from the obtained ligand 3 and Nd(NO3)3. Copolymerization of the Nd-complex monomer, styrene and divinylbenzene afforded Nd-containing polymer 8. To obtain Nd-imprinted polymer 9, Nd ion was removed by hydrochloric acid. A non-imprinted polymer 6 composed by 3, styrene and divinylbenzene was also synthesized. Elemental analysis revealed that the content of chelidonic acid monoamide ligand in the 6 and 9 is 1.70 and 1.56 mmol·g−1, respectively. BET method indicated that 6 and 9 has specific surface area of 14.7 and 1.51 m2·g−1, respectively. Nd adsorption experiments revealed 9 exhibits imprinting factor (IF) 4.3 at initial concentration 0.4 mmol-Nd/L, despite 9 has 0.92-fold of ligands and 0.1-fold of specific surface area of 6. Mixed ion solution including Nd, Dy, Cu, Zn, and Co was used as a model solution for an adsorption experiment. 9 exhibits high lanthanide selectivity in a range of pH of 3.0–7.0 and a maximum adsorption amount at pH 3.75, despite 6 shows the maximum at pH 5.0. Density functional theory (DFT) calculation of a model system revealed that the ion-imprint effect and inhibition effect is cause of large adsorption amount of 9.