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This paper presents a novel series of chemically stable and redox-switchable 20π, 19π, and 18π 5,10,15,20-tetraaryl-5,15-diazaporphyrinoids (TADAPs) that have two alkyl-chain straps above and below the diazaporphyrin ring. Three types of doubly strapped TADAPs were prepared as nickel(II) complexes using meso - N -(2,6-dihydroxyphenyl)-substituted TADAP and the corresponding aliphatic diacids as precursors. Theoretical calculations revealed that regardless of their oxidation states, all strapped TADAPs had essentially flat π-planes. It was found that the alkyl-chain straps slightly affected the optical and electrochemical properties of the DAP rings, particularly in the oxidized forms. 1 H NMR spectroscopy was used to evaluate the antiaromatic character of the 20π TADAPs and the aromatic character of the 18π TADAP dications, and it was observed that they displayed paratropic and diatropic ring-current effects, respectively, on the chemical shifts of methylene protons in the spatially separated alkyl chains. The degree of shielding and deshielding depended on the position of the methylene units; it decreased with increase in separation from the π-plane and central axis of the porphyrin ring. The NMR experiments also revealed that the degree of the diatropic ring currents was clearly related to the π-electron density of the porphyrin ring; the ring-current effects decreased as the charge increased from 0 to +2. These findings are also qualitatively supported by the nucleus-independent chemical shifts.

Ferric hexacyanoferrate (FeHCF) or Prussian blue (PB) exhibits selective alkali ion adsorption and has great potential for use in various applications. In the present work, alkali ion (Li + , Na + , K + , and Cs + ) and water configurations in defective PB (d-PB) were studied by using the statistical mechanics of molecular liquids. The three-dimensional (3D) distribution functions of the ions and water were determined by solving the 3D-reference interaction site model (RISM) equation of systems of a unit lattice of d-PB in electrolyte solutions, i.e., LiCl, NaCl, KCl, and CsCl. The results show the difference in the ion-water configurations and distributions between small (Li + and Na + ) and large ions (K + and Cs + ). The adsorption sites of Li + and Na + are located off-center and lie on the diagonal axis. By contrast, the larger ions, K + and Cs + , are adsorbed at the center of the unit cell. The degree of dehydration due to the adsorption of alkali ions indicates that there was no water exchange during Li + and Na + adsorption, whereas two and three water molecules were removed after adsorption of K + or Cs + in the unit cell.

The effect of molecular orientational correlations on the solvation free energy (SFE) of one-dimensional and three-dimensional reference interaction site models (1D- and 3D-RISM) is investigated. The repulsive bridge correction (RBC) and the partial wave (PW) expansion are representative approaches for accounting for the orientational correlation partially lacking in original 1D- and 3D-RISM. The SFEs of 1D- and 3D-RISM for a set of small organic molecules are compared with the simulation results. Accordingly, the SFE expressions, based on RBC and PW, provide more accurate results than those of the uncorrected HNC or KH SFE expressions, which indicates that accounting for molecular orientational dependencies significantly contributes to the improvement of the SFE. The SFE component analysis indicates that the nonpolar component mainly contributes to the correction. The dependence of the error in the RISM SFE on the number of solute sites is examined. In addition, we discuss the differences between 1D- and 3D-RISM through the effect of these corrections.

The molecular and solvation structures of the hydrated Cu 2+ ions and their excitation spectra were investigated using the Kohn-Sham density functional theory (DFT) and the three-dimensional reference interaction site model (3D-RISM) self-consistent field method. Five stable geometrical structures were found to exist in aqueous solution: the distorted octahedral [Cu(H 2 O) 6 ] 2+ in C i and D 2 h symmetries, the square pyramidal and trigonal bipyramidal [Cu(H 2 O) 5 ] 2+ , and the square planar [Cu(H 2 O) 4 ] 2+ . The distorted octahedral structure in the C i symmetry is preferred in [Cu(H 2 O) 6 ] 2+ , and the square pyramidal and trigonal bipyramidal [Cu(H 2 O) 5 ] 2+ show almost the same stability. Among these geometries, the six-coordinate complex [Cu(H 2 O) 6 ] 2+ in the C i symmetry had the lowest Helmholtz energy. [Cu(H 2 O) 6 ] 2+ had a distorted octahedral structure, that is, two long axial bonds and four short equatorial bonds. The spatial and radial distribution function analyses for [Cu(H 2 O) 5 ] 2+ and [Cu(H 2 O) 4 ] 2+ showed that [Cu(H 2 O) 5 ] 2+ and [Cu(H 2 O) 4 ] 2+ had one and two solvent water molecules that constituted a distorted octahedron with ligand water distribution. The coordination numbers (CNs) derived from the distribution functions were 5.2-5.4 for [Cu(H 2 O) 5 ] 2+ and 5.3 for [Cu(H 2 O) 4 ] 2+ . These results indicated that the Cu 2+ ion in an aqueous solution had 5-6 coordination water molecules in the first hydration shell and some structures with different CNs may interchange in the solution. The excitation energies and electronic configurations of low-lying d-d excited states were calculated using the time-dependent DFT with the electric field generated by 3D-RISM. The orbital energies and electronic configurations were in a similar picture to those of the classical crystal field theory because of the highly symmetrical features of all structures. In [Cu(H 2 O) 6 ] 2+ , the degeneracies of orbitals were resolved, whereas in [Cu(H 2 O) 5 ] 2+ and [Cu(H 2 O) 4 ] 2+ , weak and strong quasi-degeneracies remained. As a result, only the four-coordinate complex generated third and fourth excited states, whereas in other complexes, there were no obvious characters of degeneracies. The resulting excitation energies were in good agreement with the absorption spectra.

A scheme for quantitatively computing the acid dissociation constant, pKa, of hydrated molecules is proposed. It is based on the three-dimensional reference interaction site model self-consistent field (3D-RISM-SCF) theory coupled with the linear fitting correction (LFC) scheme. In LFC/3D-RISM-SCF, pKa values of target molecules are evaluated using the Gibbs energy difference between the protonated and unprotonated states calculated by 3D-RISM-SCF and the parameters fitted by the LFC scheme to the experimental values of training set systems. The pKa values computed by LFC/3D-RISM-SCF show quantitative agreement with the experimental data.

Bicyclo[2.2.2]octadiene (BCOD) fused azuliporphyrins were synthesized by 3+1 porphyrin synthesis of azulitripyrranes with diformylpyrroles. Subsequent retro-Diels-Alder reaction of the BCOD-fused azuliporphyrins afforded azulibenzo-, azulidibenzo-, and azulitribenzoporphyrins 1-5. NMR and UV/Vis spectra, as well as nucleus-independent chemical shift (NICS) calculations revealed that 1-5 and their diprotonated dications exhibit relatively low porphyrinoid aromaticity, which was dependent on the position and number of fused benzene rings present., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The present paper reports the first comprehensive study on the synthesis, structures, optical and electrochemical properties, and peripheral functionalizations of nickel(II) and copper(II) complexes of β-unsubstituted 5,15-diazaporphyrins (M-DAP; M = Ni, Cu) and pyridazine-fused diazacorrinoids (Ni-DACX; X = N, O). These two classes of compounds were constructed starting from mesityldipyrromethane by a metal-template method. Ni-DAP and Cu-DAP were prepared in high yields by the reaction of the respective metal-bis(dibromodipyrrin) complexes with NaN(3)-CuX (X = I, Br), whereas Ni-DACN and Ni-DACO were formed as predominant products by the reaction with NaN(3). In both cases, the metal centers change their geometry from tetrahedral to square planar during the aza-annulation; X-ray crystallographic analyses of M-DAPs showed highly planar diazaporphyrin π planes. The Q band of Ni-DAP was redshifted and intensified compared with that of a nickel-porphyrin reference, due to the involvement of electronegative nitrogen atoms at the meso positions. It was found that the peripheral bromination of Ni-DAP and Ni-DACO occurred regioselectively to afford Ni-DAP-Br(4) and Ni-DACO-Br, respectively. These brominated derivatives underwent Stille reactions with tributyl(phenyl)stannane to give the corresponding phenylated derivatives, Ni-DAP-Ph(4) and Ni-DACO-Ph. On the basis of the absorption spectra and X-ray analysis, it has been concluded that the attached phenyl groups efficiently conjugate with the diazaporphyrin π system. The present results unambiguously corroborate that the β-unsubstituted DAPs and DACXs are promising platforms for the development of a new class of π-conjugated azaporphyrin-based materials., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The solvent effect on the absorption spectra of coumarin 120 (C120) in water was studied utilizing the combined quantum mechanical∕molecular mechanical (QM∕MM) method. In molecular dynamics (MD) simulation, a new sampling scheme was introduced to provide enough samples for both solute and solvent molecules to obtain the average physical properties of the molecules in solution. We sampled the structure of the solute and solvent molecules separately. First, we executed a QM∕MM MD simulation, where we sampled the solute molecule in solution. Next, we chose random solute structures from this simulation and performed classical MD simulation for each chosen solute structure with its geometry fixed. This new scheme allowed us to sample the solute molecule quantum mechanically and sample many solvent structures classically. Excitation energy calculations using the selected samples were carried out by the generalized multiconfigurational perturbation theory. We succeeded in constructing the absorption spectra and realizing the red shift of the absorption spectra found in polar solvents. To understand the motion of C120 in water, we carried out principal component analysis and found that the motion of the methyl group made the largest contribution and the motion of the amino group the second largest. The solvent effect on the absorption spectrum was studied by decomposing it in two components: the effect from the distortion of the solute molecule and the field effect from the solvent molecules. The solvent effect from the solvent molecules shows large contribution to the solvent shift of the peak of the absorption spectrum, while the solvent effect from the solute molecule shows no contribution. The solvent effect from the solute molecule mainly contributes to the broadening of the absorption spectrum. In the solvent effect, the variation in C-C bond length has the largest contribution on the absorption spectrum from the solute molecule. For the solvent effect on the absorption spectrum from the solvent molecules, the solvent structure around the amino group of C120 plays the key role.

The correlation energies (CEs) of the He isoelectronic sequence Z=2-116 with a point nuclear charge model were investigated with the four component relativistic configuration interaction method. We obtained CEs with and without the virtual pair approximation which are close to the values from Pestka et al.'s Hylleraas-type configuration interaction calculation. We also found that the uniform charge and point charge models for the nucleus differ substantially for Z > or = 100.

The electronic structure of the LaO molecule is studied using frozen-core four-component multiconfigurational quasidegenerate perturbation theory. The ground state and nine experimentally observed excited states are examined. The ground state is (2)Sigma(1/2)(+) and its gross atomic orbital population is La(5p(5.76)6s(0.83)6p(0.14)p(*(0.21) )d(*(1.17) )f(*(0.26) )) O(2p(4.63)), where p*, d*, and f* are the polarization functions of La that form molecular spinors with O 2ps. We found that it is not necessary to consider the excitation from the O 2p electrons when analyzing the experimental spectra. This validates the foundation of the ligand field theory on diatomic molecules, including the La atom where only one electron is considered. The spectroscopic constants R(e), omega(e), and T(0) calculated for the ground state and low-lying excited states A'((2)Delta(3/2)), A'((2)Delta(5/2)) A((2)Pi(1/2)), and A((2)Pi(3/2)) are in good agreement with the experimental values.

The nature of chemical bonds on dynamic paths was investigated using the complete active space valence-bond (CASVB) method and the Born-Oppenheimer dynamics. To extract the chemical bond picture during reactions, a scheme to collect contributions from several VB (resonance) structures into a small numbers of indices was introduced. In this scheme, a tree diagram for the VB structures is constructed with the numbers of the ionic bonds treated as generation. A pair of VB structures is related to each other if one VB structure is transferred into the other by changing a covalent bond to an ionic bond. The former and latter VB structures are named parent and child structures, respectively. The weights of the bond pictures are computed as the sum of the CASVB occupation numbers running from the top generation to the bottom along the descent of the VB structures. Thus, a number of CASVB occupation numbers are collected into a small number of indices, and a clear bond picture may be obtained from the CASVB wave function. The scheme was applied to the hydrogen exchange reaction H(2)+F-->H+HF and the Diels-Alder reaction C(5)H(6)(cyclopentadiene)+CH(2)=CH(2)(ethylene)-->C(7)H(10)(norbornene). In both the reactions, the scheme gave a clear picture for the Born-Oppenheimer dynamics trajectories. The reconstruction of the bonds during reactions was well described by following the temporal changes in weight.

We have investigated the ground state and the two lowest excited states of the CeF molecule using four-component relativistic multiconfigurational quasidegenerate perturbation theory calculations, assuming the reduced frozen-core approximation. The ground state is found to be (4f(1))(5d(1))(6s(1)), with Omega = 3.5, where Omega is the total electronic angular momentum around the molecular axis. The lowest excited state with Omega = 4.5 is calculated to be 0.104 eV above the ground state and corresponds to the state experimentally found at 0.087 eV. The second lowest excited state is experimentally found at 0.186 eV above the ground state, with Omega = 3.5 based on ligand field theory calculations. The corresponding state having Omega = 3.5 is calculated to be 0.314 eV above the ground state. Around this state, we also have the state with Omega = 4.5. The spectroscopic constants R(e), omega(e), and nu(1-0) calculated for the ground and first excited states are in almost perfect agreement with the experimental values. The characteristics of the CeF ground state are discussed, making comparison with the LaF(+) and LaF molecules. We denote the d- and f-like polarization functions as d(*) and f(*). The chemical bond of CeF is constructed via {Ce(3.6+)(5p(6)d(*0.3)f(*0.1))F(0.6-)(2p(5.6))}(3+) formation, which causes the three valence electrons to be localized at Ce(3.6+).

The 18pi-sigma3- and 22pi-sigma4-phosphaporphyrins were successfully prepared by an acid-promoted condensation between a phosphatripyrrane and a 2,5-bis[hydroxy(phenyl)methyl]pyrrole, and their structures, aromaticity, and optical and electrochemical properties were disclosed. Notably, a sigma4-phosphaporphyrinogen and the 18pi-sigma3-phosphaporphyrin undergo oxidative pi-extension at the peripherally fused carbocycle to afford the 22pi-sigma4-phosphaporphyrin.

The synthesis and aggregation behavior of meso-sulfinylporphyrins are described. The copper-catalyzed C-S cross-coupling reaction of a meso-iodoporphyrin with benzenethiol and n-octanethiol has proved to be an efficient method for the synthesis of meso-sulfanylporphyrins, which are oxygenated by m-chloroperbenzoic acid to produce the corresponding meso-sulfinylporphyrins. Optically active zinc meso-sulfinylporphyrins were successfully isolated by means of optical resolution of the racemates on a chiral HPLC column. Zinc sulfinylporphyrins readily undergo self-organization through S-oxo-zinc coordination to form cofacial porphyrin dimers in solution, in which the hetero- and homodimers are present as a diastereomeric mixture. The aggregation modes of the S-oxo-tethered porphyrin dimers were fully characterized by 1H NMR, IR, and UV/Vis spectroscopy as well as DFT calculations on their model compounds, thus revealing that the self-aggregation behavior depends on the combination of S chirality. The absolute configurations at the sulfur center can be determined by the exciton-coupled CD method. The observed self-association constant for the S-oxo-tethered dimerization of (S)-phenylsulfinylporphyrin in toluene is larger than that in dichloromethane, which reflects the difference in dipole moments between the homodimer and the monomer. In cyclic and differential pulse voltammetry, the first oxidation process of the cofacial dimers is split into two reversible steps, which indicates that the initially produced pi radical cations are delocalized efficiently between the two porphyrin rings. The present findings demonstrate the potential utility of meso-sulfinyl groups as promising ligands for investigating the effects of peripheral chirality on the structures and optical and electrochemical properties of metal-assisted porphyrin self-assemblies.

The correlation energies (CEs) for the He-like ions are studied with the virtual-pair approximation (VPA) and with the no-virtual-pair approximation (NVPA). In contrast to the nonrelativistic CEs, the CEs calculated with relativity fell sharply as the nuclear charge Z increased, although the CE calculated with the NVPA was considerably lower than with the VPA for the heavier atoms. It is shown that CE calculated with a Hylleraas-type function implicitly includes the effects of the excitations into negative-energy states, which corresponds to the VPA. The present results verify that the strong dependence on Z of the CE of He-like ions is an essential effect of the relativity.

We study the electronic structure of the ground state of the manganese dimer using the state-averaged complete active space self-consistent field method, followed by second-order quasidegenerate perturbation theory. Overall potential energy curves are calculated for the 1Sigmag+, 11Sigmau+, and 11Piu states, which are candidates for the ground state. Of these states, the 1Sigmag+ state has the lowest energy and we therefore identify it as the ground state. We find values of 3.29 A, 0.14 eV, and 53.46 cm(-1) for the bond length, dissociation energy, and vibrational frequency, in good agreement with the observed values of 3.4 A, 0.1 eV, and 68.1 cm(-1) in rare-gas matrices. These values show that the manganese dimer is a van der Waals molecule with antiferromagnetic coupling.

Relativistic quasidegenerate perturbation theory (QDPT) using general multiconfiguration (GMC) reference functions is developed and implemented. It is the relativistic counterpart of the nonrelativistic QDPT with GMC reference and thus retains all the advantages of the nonrelativistic GMC reference QDPT, such as applicability to any configuration space and small computational cost compared to the complete configuration-space case. The method is applied to the potential-energy curves of the ground states of I(2) and Sb(2) molecules, the excitation energies of CH(3)I, and the energies of the lowest terms of C, Si, and Ge atoms, and is shown to provide a balanced description of potential-energy curves and accurate transition energies for systems containing heavy elements and to provide much better results compared to the reference function (i.e., active space configuration interaction) level.