A subazaporphyrin (SubAP), tert-butylated and crowned subphthalocyanines (tBSubPc and SubCRPc), a μ-oxo dimer of tert-butylated SubPc {(tBSubPc)2O}, a subnaphthalocyanine (SubNc), and monosubstituted type unsymmetrical phthalocyanine (Pc) and naphthalocyanine (Nc) analogues have been synthesized. In particular, unsymmetrical Pc's and Nc's have been prepared in moderate yields by the ring expansion reaction of structurally distorted SubPc's and SubNc's with isoindolediimine derivatives in dimethyl sulfoxide−chloronaphthalene (or chlorobenzenes or aromatic hydrocarbons such as toluene and xylene) mixtures. The compounds have been characterized by electronic absorption, magnetic circular dichroism (MCD), fluorescence emission, and nuclear magnetic resonance spectroscopy. Both the Soret bands and Q-bands shift to longer wavelength and gain intensity in the order SubAP, SubPc, and SubNc. Fluorescence quantum yields and lifetimes generally decrease with decreasing molecular symmetry. Circular dichroism and NMR spectroscopy have revealed that a SubPc with three 15-crown-5 ether voids having a phenyl group as an axial ligand (SubCRPc) forms inclusion complexes with 2,6-dimethyl-β-cyclodextrin in acetonitrile or water−acetonitrile mixtures, while the electronic absorption spectroscopy suggests that it is not dimerized by the addition of cations such as K+, Rb+, Ce+, i.e., cations which are effective in dimerizing Pc's with 15-crown-5 ether voids. Molecular orbital (MO) calculations within the framework of the Pariser−Parr−Pople approximation have succeeded in reproducing the optical absorption experimental data of not only the parent subazamacrocycles but also Pc derivatives with lower symmetry obtained by the ring expansion reaction. The correspondence between MO calculations and experiments suggests strongly that, in the metal-free unsymmetrical Pc's, two pyrrole hydrogen atoms are bound to the nitrogens along the short axis. Comparison of formation, bonding, and donation energies between SubPc and typical Pc, i.e., MgPc by natural bond orbital analysis, suggests that the distortion energy is not the major reason for the ring expansion reactivity of SubPc, and that the lack of donor−acceptor stabilization in B−N(pyrrole) bonds destabilizes SubPc. Band deconvolution of the electronic absorption and MCD spectra of SubPc with the same set of bands (with the same centers and width) experimentally identified that the excited state of the Q-band of SubPc is orbitally degenerate, with three degenerate transitions located in the 250−450-nm region. In particular, the transition at 359 nm corresponds to a shoulder seen on the red side of the Soret band tail. Time-resolved EPR analysis has shown that the size of the π-system of SubPc is, indeed, smaller than that of Pc's.

Cross polarization/magic angle spinning (CP/MAS)(13)C (solid state high resolution) NMR spectra were observed for chlorosomes and BChlc aggregates. Similarity of both kinds of spectra (except for some signals assignable to proteins and lipids in chlorosomes) indicates that BChlc's in chlorosomes are present just as in synthetic BChlc aggregates. Chemical shifts for C13(1) carbonyl and C3(1) hydroxylethyl carbons indicate hydrogen bonding between them. Comparison of solution and solid state(13)C NMR chemical shifts shows the five coordinated nature of BChlc aggregates. Some chemical shift differences were attributable to ring currents shifts. Their comparisons with calculated ring current shift values predicted structures for the aggregates. Cross polarization dynamics of the CP/MAS(13)C NMR signals explored dynamic and structural nature of the BChlc aggregates.

Photoinduced electron transfer between fullerenes (C60 and C70) and phthalocyanines such as tetra-tert-butylphthalocyanine (H2TBPc) and its zinc derivative (ZnTBPc) in solution has been investigated with nanosecond laser photolysis method by observing the transient absorption bands in the visible/near-IR regions. By the predominant excitation of fullerenes with 532 nm laser light, slow rises of the transient absorption bands of phthalocyanine cation radicals and fullerene anion radicals were observed instead of the decays of the excited triplet states of fullerenes (TC60* and TC70*) in polar solvents. Electron-transfer from the phthalocyanines to TC60* or TC70* was confirmed. The quantum yield of the electron transfer via TC70* is higher than that via TC60*; ZnTBPc acts as stronger electron donor than H2TBPc. In nonpolar solvent, energy transfer from TC60* (and TC70*) to the phthalocyanines occurs predominantly as confirmed by the consecutive appearance of the triplet states of the phthalocyanines.

Second-order hyperpolarizabilities (β), electron distribution, dipole moment, and excitation energy together with oscillator strength of stilbazolium cations have been investigated by a semiempirical calculation with PM3 parametrization of the MNDO Hamiltonian. Since stilbazoliums were found to generally have several times larger β value than nitrostilbene derivatives with similar experimental absorption maximum wavelength, such ionic species are concluded to be advantageous to create new second-order nonlinear optical materials having large β and short cutoff. Among the stilbazolium derivatives investigated, the β values increase with increasing electron-donating ability of the substituent at the para position of benzene ring, and exceptionally chlorinated one was found to have comparatively large β value withstanding its short absorption maximum wavelength. The main reason for the large β values of stilbazolium cations is the strong acceptor property of the pyridinium ring resulting in large difference in dipole moment between the ground and excited states, which could be shown using the two-level model. The tendency of calculated β values of stilbazolium cations shows good agreement with that obtained from the hyper Rayleigh scattering (HRS) measurement.

Ion Binding to Poly(oxyethylene) in Methanol latter for the p-nitroperbenzoic acid results could be appreciable. Effect of Brownian Motion of the LigandWhen the target area is smaller than the mean free path of the ligand, the diffusion-controlled rate constant cannot be deduced from a simple diffusion equation.36 However, the mean free path, L, calculated from the following equation36 is only 0.07 Á for p-nitroperbenzoic acid, where M is molecular weight and R is gas constant: L D( §iY Therefore, the effect of Brownian motion is almost negligible for the horseradish peroxidase-ligand system. Publication costs assisted by Tohoku UniversityThe binding of alkali metal cation with poly(oxyethylene) was studied by means of conductometry in methanol. Apparent binding constants, KA, were determined by assuming the existence of discrete binding sites distributed every a monomer units along the polymer chain. KA increased in the order Li < Na < K < Cs < Rb. For large anions, such as thiocyanate or perchlorate, the formation of an ion pair complex was indicated. KA and a increased rapidly with decreasing salt concentration. This result was interpreted by the increased electrostatic repulsion between bound ions. The linear relationship between a1/2 and Cs"1/2 conforms to the Gaussian distribution of the segment between charges as well as to the partial retention of crystalline conformation of the poly-(oxyethylene)-ion complex.Publication costs assisted by the National Science Foundation and the Petroleum Research Fund Two recent theories for ionic mobility, the Hubbard-Onsager theory which is based on a continuum model and the Wolynes theory which is based on a stochastic model, are critically tested by comparison with conductance data. Both theories predict finite mobilities as the ionic size decreases and thus can successfully account for many of the observed features of conductance data. The models upon which the theories are based are described in detail and the current state of ionic mobility theory is discussed.

No abstract

Molecular orbital (MO) calculations of more than 60 porphyrinic p conjugated structures have been performed within the framework of the Pariser-Parr-Pople approximation. The results of a series of compounds are introduced and summarized in order to show how they vary depending on the systematic change in molecular structure. These are shown schematically or itemized. Our results are compared with the spectra of the corresponding known compounds and with the MO results reported by previous workers, if available. In addition, the results have continually been compared, where possible, with those of tetraazaporphyrin or phthalocyanine systems. In naphthalene-or anthracene-fused compounds, these molecule-centered orbitals often appear, and these are indicated using either triangles or circles in figures if they appear between HOMO À 3 and LUMO 3 orbitals.

No abstract