Synthesis and photoluminescence properties of BF2 complexes with 1,3-diketone ligands

BF₂ complexes with 1,3-diketone ligands were synthesized, and their optical and electrochemical properties were studied. The colors of the complexes varied depending on the structures of the 1,3-diketone ligands. The absorption and emission maxima of the complexes with 1,3-diaryl-1,3-diketone ligands were considerably red shifted as compared to those of the complexes with 1-aryl-3-trifluoromethyl-1,3-diketone ligands, suggesting an extended π-conjugation of the 1,3-diaryl-1,3-diketone moieties. The molar absorption coefficients and quantum yields of the complexes with 1,3-diaryl-1,3-diketone ligands were larger than those of the complexes with 1-aryl-3-trifluoromethyl-1,3-diketone ligands. Cyclic voltammetry measurements revealed that the reduction potentials of the BF₂ complexes were higher than those of the free ligands. These complexes exhibited various emission colors in the solid states due to the intermolecular interactions.     

Radical copolymerization of proto-hemin dimethyl ester

Iron(III) proto-porphyrin IX dimethyl ester (HDME) can copolymerize with π-conjugated monomers binding at one end of the polymer chain. Apparent Q, e values of HDME were Q = 70 and e = ?0.17. The copolymerization of HDME with π-unconjugated monomer was feasible by using π-conjugated monomer as a third component. When unconjugated vinylimidazoles were used as monomers, the obtained ternary copolymers of HDME formed intramacromolecular complexes of iron(II) porphyrin with vinylimidazole residues, which gave stable carbon monoxide adducts.     

Electrostatic Interaction between Two Dissimilar Spheres with Constant Surface Charge Density

Explicit exact analytic expressions are obtained in the form of infinite series for the potential energy of the electrostatic interaction for the system of two dissimilar hard spheres with constant surface charge density in an electrolyte solution on the basis of the linearized Poisson-Boltzmann equation. The effects of the particle polarization, that is, the internal fields induced within tim interacting spheres, which are found to be of the order of instead of 1/κa (where κ is the Debye-Hückel parameter and a is the sphere radius), are taken into account. As in the case of the interaction at constant surface potential, the zeroth-order approximation to the interaction energy corresponds to the interaction energy that would be obtained if both spheres were ion-penetrable spheres ("soft" spheres) and to that obtained by the linear superposition approximation. The first-order approximation corresponds to the interaction energy that would be obtained if either sphere were a soft sphere, with the other being a hard sphere with constant surface charge density. The first-order correction term can be interpreted as the image interaction between the soft sphere and its image with respect to the hard sphere.     

Novel synthesis, static and dynamic properties, and structural characteristics of 5-cyano[n](2,4)pyridinophane-6-ones (n= 9-6) and their chemical transformations

A novel synthesis of 5-cyano[n](2,4)pyridinophane-6-ones 12a-d (n= 9, 8, 7, and 6) consists of allowing cyanoacetatoamide to react with cycloalk-2-enones. Their static and dynamic properties as well as structural characteristics are studied on the basis of their spectroscopic properties, cyclic voltammetry, and theoretical calculations. The (1)H and (13)C NMR spectra at various temperatures have clarified the dynamic behavior of the methylene chains for [7](2,4)- and [6](2,4)pyridinophane-6-one derivatives 12c and 12d. The energy barrier (Delta G(++)) of the bridge flipping of 12c is estimated to be 12.0 kcal mol(-1)(T(c)= 0 degree C). On the other hand, compound 12d undergoes pseudorotation (conformational change of the methylene chain) at room temperature, and does not undergo bridge flipping even at 150 degree C in DMSO-d(6). The energy barrier (Delta G(++)) of the pseudorotation of the methylene chain 12d of is found to be 10.5 kcal mol(-1)(T(c)=-25 degree C), and thus, two stable conformers of the hexamethylene bridge of 12d are determined as predicted by theoretical calculations. Deformation of the pyridone ring of 12d is also determined by X-ray crystallographic analysis. Furthermore, chemical transformations of 12a-c leading to 5-carbamoyl[n](2,4)pyridinophanes 15a-c are also accomplished successfully in moderate to good yields.     

Mononuclear five-coordinate molybdenum(IV) and -(V) monosulfide complexes coordinated with dithiolene ligands: reversible redox of Mo(V)/Mo(IV) and irreversible dimerization of [MoVS]- cores to a dinuclear [MoV2(mu-S)2]2- Core

A mononuclear five-coordinate molybdenum(IV) monosulfide complex, (Et4N)2[MoS(L)2] (L = cyclohexene-1,2-dithiolate) (1), was obtained and characterized by IR, UV-vis spectroscopic methods, and X-ray crystallography. 1 was oxidized by an equivalent ferrocenium cation to give the corresponding mononuclear molybdenum(V) complex, (Et4N)[MoS(L)2] (2), which was stable for a few minutes under a lower concentration than 0.3 mM and then further dimerized to (Et4N)2[Mo(L)2]2(mu-S)2 (3).     

A theory of adsorption kinetics with time delay and its application to overshoot and oscillation in the surface tension of gelatin solution

A theory of adsorption kinetics with time delay [Ohshima et al. (1992) Colloid Polym. Sci. 270:707] is developed and applied to the surface tension of a polymer solution. It is found that the general appearance of the overshoot and oscillation in the time course of the surface tension of aqueous gelatin solution observed by Sato and Ueberreiter [(1979) Makromol. Chem. 180:829, 1107; (1979) Polym. Prepr. Am. Chem. Soc. Div. Polym. Chem. 20:907) can be explained by the present theory.     

Structures of a CO adlayer on a Pt(100) electrode in HClO4 solution studied by in situ STM

We have obtained the first in situ STM atomic images of a CO adlayer on a Pt(100)-(1 x 1) electrode in 0.1 M HClO(4) solution, exhibiting a phase transition from c(6 x 2)-10CO to c(4 x 2)-6CO at E > 0.3 V vs. RHE.     

Dynamic coordination polymers with 4,4'-oxybis(benzoate): reversible transformations of nano- and nonporous coordination frameworks responding to present solvents

Reversible construction of a nanoporous framework from a nonporous framework has been found in the zinc(II) coordination polymer with 4,4'-oxybis(benzoate) (oba). [Zn(2)(oba)(2)(dmf)(2)].2DMF (1), which has 1 nm scale channels, transforms to the nonporous coordination polymer [Zn(oba)(H(2)O)] (2) with the loss of the open framework. Compound 2 on treatment with DMF reversibly yields nanoporous compound 1.     

Chemoenzymatic synthesis of (+)-totarol, (+)-podototarin, (+)-sempervirol, and (+)-jolkinolides E and D

The enzymatic resolution products [(1R,4aR,8aR)-1,2,3,4,4a,5,6,7,8,8a-decahydro-5,5,8a-trimethyl-2-oxo-trans-naphthalene-1-methanol-2-ethylene acetal (8aR)-7 (98% ee) and {acetate of (1S,4aS,8aS)-1,2,3,4,4a,5,6,7,8,8a-decahydro-5,5,8a-trimethyl-2-oxo-trans-naphthalene-1-methanol-2-ethylene acetal} (8aS)-9 (>99% ee)] obtained by the lipase-catalyzed enantioselective acetylation of (±)-7 in the presence of vinyl acetate as an acyl donor were converted to the ,β-unsaturated ketones (8aR)-6 and (8aS)-6, respectively. Concise syntheses of (+)-totarol 1, (+)-podototarin 2 and (+)-sempervirol 3 were achieved based on Michael reactions between (8aS)-6 and the appropriate β-keto ester followed by aldol condensation. The first chiral syntheses of (+)-jolkinolides E 4 and D 5 were achieved from (5R,10R,12R)-12-hydroxypodocarpa-8(14)-en-13-one 15 derived from (8aR)-6.     

Heavenly blue anthocyanin II trans-4-0-(6-0-(trans-3-0-(β -d-glucopyranosyl)caffeyl)-β-d-glucopyranosyl)- caffeic acid,a novel component in heavenly blue anthocyanin

Structure of an alkaline hydrolysis product of heavenly blue anthocyanin was determined to be $\text{trans}$-4-0-(6-0-($\text{trans}$-3-0-(β-D-glucopyranosyl)caffeyl)-β-D- glucopyranosyl)caffeic acid ($\text{1}$).