Photodecarbonylation of ruthenium carbonyl octaethylporphyrin via stepwise two-photon absorption of visible light

The photoinduced decarbonylation of a ruthenium(II) carbonyl octaethylporphyrin (RuOEP(CO)(Py)) complex has been shown to occur upon nanosecond pulse laser irradiation as a visible light excitation source, which is reasonably interpreted by a stepwise two-photon absorption process.     

Preparation of organic-inorganic composites containing rod-like phthalocyanine polymers

Sol-gel polymerization of tetraethoxysilane in the presence of amphiphilic phthalocyanine polymer 2 produced organic-inorganic composites with the rod-like phthalocaynine polymers incorporated within ordered hexagonal channels.     

Two new tetranor-cycloartane glycosides from cimicifuga rhizome

Two new tetranor-cycloartane glycosides (1, 2) were isolated from Cimicifuga Rhizome. Their structures were determined by spectroscopic analysis. These compounds suggested the existence of a biogenetic pathway into C-23 lactone-type cycloartane glycosides.     

Selective ligation to sterically isolated metallophthalocyanines

A new class of sterically hindered phthalocyanine has been synthesized and characterized. Pentaphenylbenzene units were introduced at the periphery of each phthalocyanine to yield a sterically protected metal center. The attachment of the bulky oligophenylbenzene units resulted in the complete isolation of individual MPc molecules. The pockets around a cobalt center affect selectivity in the ligation of pyridines that have different sizes and shapes.     

Application of MCD spectroscopy and TD-DFT to nonplanar core-modified tetrabenzoporphyrins: effect of reduced symmetry on nonplanar porphyrinoids

The optical spectra of a series of core-modified tetrabenzoporphyrins were analyzed to determine the effects of core modification, ligand folding, and partial benzo substitution at the ligand periphery on the electronic structure by using magnetic circular dichroism (MCD) and NMR spectroscopy, X-ray crystallography, cyclic and differential pulse voltammetry, and TD-DFT calculations. Planar 21-carba-, 21-thia-, 21,23-dithia-, and 21-oxa-23-thiatetrabenzo[b,g,l,q]porphyrins reported previously were studied together with the previously unreported 21-oxa- and 21-carba-23-thiatetrabenzo[b,g,l,q]porphyrins. The optical properties of these compounds are compared to those of tetrabenzo[b,g,l,q]-, 5,10,15,20-tetraphenyl-, 5,10,15,20-tetraphenyltetrabenzo[b,g,l,q]-21-thia-, 5,10,15,20-tetraphenyltetrabenzodithia-, 5,10,15,20-tetraphenyldibenzo[g,q]-21,23-dithia-, 5,10,15,20-tetraphenyldibenzo[b,l]-21,23-dithia-, 5,10,15,20-tetraphenyltribenzo[g,q,l]-21-thia-, and 5,10,15,20-tetraphenylbenzo[b]-21-thiaporphyrins. Michl's perimeter model and Gouterman's four-orbital model are used to conceptualize the results and to account for red shifts commonly observed in the spectral bands of nonplanar porphyrinoids.     

NMR spectra of free-base porphine, porphyrazine, phthalocyanine and naphthalocyanine as well as their metal complexes: density functional calculations

Nuclear magnetic shielding tensors of porphine have been calculated at density functional B3LYP and PBE level using the gauge independent atomic orbital (GIAO) method. The geometries used were optimized using the 6-31G(d) basis set and the NMR calculations were performed using 6-31G(d) and 6-311G(d,p) basis sets, respectively. The calculated NMR shielding tensors and chemical shifts of porphine are compared with previous calculations as well as experimental data and satisfying results are obtained. Further NMR calculations are extended to metal-free and metallo-porphyrazine, -phthalocyanine, and -naphthalocyanine for the first time and the results are compared with experimental data available. The chemical shifts of the atoms in these compounds are assigned according to the experimental data available.     

Skeletal modification of a non-planar phthalocyanine analogue under very mild conditions

A sterically congested tetraphenyl-substituted dibenzo-tetraaza-isobacteriochlorinato nickel derivative unexpectedly reacts with methanol at room temperature to release internal molecular strains, leading to the formation of a ligand having a skeleton bearing two cis-methoxy substituents.     

Two new cycloartane glycosides from the underground parts of Aquilegia vulgaris

Two new cycloartane glycosides, named aquilegiosides K and L, have been isolated from the dried underground parts of Aquilegia vulgaris. Their structures were determined by two dimensional (2D) NMR spectroscopic analysis and chemical evidence.     

Path integral formulation for many-electron system

The Feynman path integral method is applied to the many-electron problem of quantum chemistry. We begin with constructing new closure relations in terms of the linear combination of atomic orbital (LCAO) coefficients and investigate the transition amplitude and the partition function of the system in question; then a “classical path of electrons,” which is described by the time-dependent Hartree-Fock-Roothaan equation, is obtained by minimizing the action integral of the system with respect to the “electron coordinate.” The next order approximation is obtained by evaluating the deviation from this classical path, which is approximately written by a Gaussian integral. The result is expected to be the random-phase approximation. © 1996 John Wiley & Sons, Inc.     

Reinvestigation of the synthesis of isoliquiritigenin: application of Horner-Wadsworth-Emmons reaction and Claisen-Schmidt condensation

Isoliquiritigenin [ILG, (E)-1] was readily prepared via the Horner-Wadsworth-Emmons reactions using β-ketophosphonates 5a, b. An improved protocol for the synthesis of (E)-1 via the Claisen-Schmidt condensation was also presented.