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Entoria okinawaensisShiraki, 1935 (Phasmatodea: Phasmatidae) is a stick insect originally distributed among the subtropical islands of Japan. This species, after introduction into the southernmost regions of Kyushu Island, became established there. After insects were collected for this study from Ibusuki city, Kagoshima prefecture, Japan, their eggs were used for experimentation. Embryonic development was fundamentally temperature dependent. At 25 °C, many eggs hatched approximately 2 months after oviposition. However, hatching was observed continuously until the end of the 240-day experiment. Findings from egg dissection suggest that a small number of eggs arrest development at the early embryonic stages. Fluorescence observation of DAPI-stained eggs reveals that eggs show arrested development at the very attenuated blastoderm period. This study proves the existence of embryonic diapause in E. okinawaensis, although the incidence of diapause eggs is small. If future changes in the incidence and duration of diapause as adaptations to local climate occur, then the domestic-introduced subtropical stick insect might expand its distribution range farther north.

The binding process of angiotensin-converting enzyme 2 (ACE2) to the receptor-binding domain (RBD) of the severe acute respiratory syndrome-like coronavirus 2 spike protein was investigated using molecular dynamics simulation and the three-dimensional reference interaction-site model theory. The results suggested that the protein-binding process consists of a protein–protein approaching step, followed by a local structural rearrangement step. In the approaching step, the interprotein interaction energy decreased as the proteins approached each other, whereas the solvation free energy increased. As the proteins approached, the glycan of ACE2 first established a hydrogen bond with the RBD. Thereafter, the number of interprotein hydrogen bonds increased rapidly. The solvation free energy increased because of the desolvation of the protein as it approached its partner. The spatial distribution function of the solvent revealed the presence of hydrogen bonds bridged by water molecules on the RBD–ACE2 interface. Finally, principal component analysis revealed that ACE2 showed a pronounced conformational change, whereas there was no significant change in RBD.

The synthesis, excited state dynamics, and substituent effect on the 1O2-generation efficiency of several copper(II) complexes of 5,15-diazaporphyrin (CuDAPs) bearing peripheral substituents are reported. 10,20-Diaryl-CuDAPs were prepared via a new method consisting of metal-templated cyclization and N-dealkylation as key steps. The effect of the β-substituents on the optical and redox properties of CuDAP was stronger than that of the meso-aryl groups, which can be explained by considering the characteristics of the HOMO and LUMO of the DAP ring. The excited state dynamics and 1O2-generation efficiency of CuDAPs were studied using time-resolved spectroscopic techniques; the electronic effect of the meso-aryl groups on the triplet lifetime and 1O2-generation quantum yield was relatively weak, whereas that of the β-(1-pyrazolyl) groups was appreciable. The analysis of the temperature dependence of phosphorescence spectra of 10,20-bis(2,4,6-trimethylphenyl)-CuDAP allowed the energy gap between the excited trip-quartet and trip-doublet states to be determined. The relatively long triplet lifetimes of CuDAPs show their potential for future application as photosensitizers.Several copper(II) complexes of 5,15-diazaporphyrin (CuDAPs) bearing peripheral substituents were prepared via a new method consisting of metal-templated cyclization and N-dealkylation as key steps. The excited state dynamics and substituent effects on the 1O2-generation efficiency of CuDAPs were studied using time-resolved spectroscopic techniques.

We report herein an improved method for the quantitative preparation of free bases of 5,10,15,20-tetraaryl-5,15-diazaporphyrinoid (TADAP) using Me3SiBr–MeOH to treat the corresponding zinc(II) complexes. Metallation of the free base with HSiCl3followed by Si–X metathesis with SbF3and redox reactions afforded difluorosilicon(IV) complexes of TADAP.Free bases of 5,10,15,20-tetraaryl-5,15-diazaporphyrinoid (TADAP) were easily prepared using Me3SiBr–MeOH to treat the corresponding zinc(II) complexes. The first examples of difluorosilicon(IV) complexes of TADAP were successfully prepared from the free base and trichlorosilane.

The applicability of the linear fitting correction with the three-dimensional reference interaction-site model self-consistent field (LFC/3D-RISM-SCF) scheme, a pKaprediction scheme, for methanol solutions was investigated. The correlation between experimental and predicted pKavalues of dissociative molecules with phenol, amine, and carboxyl derivatives was examined. The pKavalues of the LFC/3D-RISM-SCF results showed a good linear correlation with the experimental pKa. This result demonstrates that the LFC/3D-RISM-SCF method can be applied to a variety of solvents other than water.The applicability of the linear fitting correction with the three-dimensional reference interaction-site model self-consistent field (LFC/3D-RISM-SCF) scheme, a pKaprediction scheme, for methanol solutions was investigated. The correlation between experimental and predicted pKavalues of dissociative molecules with phenol, amine, and carboxyl functional groups was examined. The pKavalues of the LFC/3D-RISM-SCF results showed a good linear correlation with the experimental pKa. This result demonstrates that the LFC/3D-RISM-SCF method can be applied to a variety of solvents other than water.

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 uncorrectedHNC 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 Cu2+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(H2O)6]2+in Ciand D2hsymmetries, the square pyramidal and trigonal bipyramidal [Cu(H2O)5]2+, and the square planar [Cu(H2O)4]2+. The distorted octahedral structure in the Cisymmetry is preferred in [Cu(H2O)6]2+, and the square pyramidal and trigonal bipyramidal [Cu(H2O)5]2+show almost the same stability. Among these geometries, the six-coordinate complex [Cu(H2O)6]2+in the Cisymmetry had the lowest Helmholtz energy. [Cu(H2O)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(H2O)5]2+and [Cu(H2O)4]2+showed that [Cu(H2O)5]2+and [Cu(H2O)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(H2O)5]2+and 5.3 for [Cu(H2O)4]2+. These results indicated that the Cu2+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(H2O)6]2+, the degeneracies of orbitals were resolved, whereas in [Cu(H2O)5]2+and [Cu(H2O)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.

Nickel(II) and copper(II) complexes of redox‐switchable 20π, 19π, and 18π 5,15‐dialkyl‐10,20‐diaryl‐5,15‐diazaporphyrins were prepared through a metal‐templated cyclization method. Furthermore, the terminal silyloxy groups in the peripheral N‐alkyl chains were transformed into hydroxy groups by deprotection. It is worth noting that redox reactions between the 19π and 18π systems bearing hydroxy groups caused a change in the water solubility of the diazaporphyrin chromophore. Complex Pi(e): Nickel(II) and copper(II) complexes of redox‐switchable 20π, 19π, and 18π 5,15‐dialkyl‐10,20‐diaryl‐5,15‐diazaporphyrins were prepared, and the peripheral N‐alkyl chains were transformed into hydrophilic groups. Notably, redox reactions between the 19π and 18π systems bearing the hydroxy groups caused a change in the water solubility of the diazaporphyrin chromophore.

The role of water in host–ligand binding was investigated using a combination of molecular dynamics simulation and three-dimensional reference interaction site model theory. Three different hosts were selected (CB6, CB7, and CB8). Six organic molecules were used as representative ligands: dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), acetone, 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO), cyclopentanone (CPN), and pyrrole. From the binding free energy and its components, we divided the ligands into two groups: those with relatively small molecular size (DMSO, DMF, acetone, and pyrrole) and those with relatively large molecular size (DBO and CPN). We established that the solvent water in the CB6 cavity can be completely displaced by small ligands, resulting in a greater binding affinity compared with larger CBs, except in the case of the small pyrrole ligand, due to outstanding intrinsic properties such as the relatively high hydrophobicity and low dipole moment. In the case of the large ligands, the solvent water can be displaced by DBO and CPN in both CB6 and CB7; there were similar tendencies in their binding affinities, with the greatest affinity in the CB7 complexes. However, the tendencies of the binding affinity components are completely different due to the difference between the complex structure and the solvation structure when a ligand binds with a CB structure. The binding affinities suggest that the size fit between the ligand and CB cannot guarantee the greatest binding affinity gain because the binding structure and intrinsic properties of CB and ligand equally play a crucial role.

The ß-functionalization of 5,15-diazaporphyrins (DAPs) with phosphoryl, phenoxy, sulfanyl, and sulfonyl groups was achieved by either cross-coupling or aromatic nucleophilic substitution reactions of ß-bromo- and ß,ß'-dibromo-DAPs. The heteroatom-containing functional groups at the ß-positions strongly affected the redox properties of the DAP p-systems.Convenient methods to introduce P-, O-, and S-containing functional groups onto the ß-positions of a DAP ring were established. The electron-withdrawing sulfonyl groups not only enhanced the electrophilicity of the 18p DAP ring but also energetically stabilized the 20p H2DAP ring. In addition, the ß-phosphoryl- and ß-phenoxy-DAPs effectively generated singlet oxygen under visible-light irradiation.

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 NaN3–CuX (X=I, Br), whereas Ni‐DACN and Ni‐DACO were formed as predominant products by the reaction with NaN3. 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 mesopositions. It was found that the peripheral bromination of Ni‐DAP and Ni‐DACO occurred regioselectively to afford Ni‐DAP‐Br4and Ni‐DACO‐Br, respectively. These brominated derivatives underwent Stille reactions with tributyl(phenyl)stannane to give the corresponding phenylated derivatives, Ni‐DAP‐Ph4and 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.

A new, efficient parallel algorithm for four-component relativistic generalized multiconfigurational quasidegenerate perturbation theory (GMC-QDPT) introducing Kramers symmetry is implemented. Because it utilizes the independence of the terms in the matrix element computations, this algorithm both speeds up the calculation and reduces the computational resources required for each node. In addition, the amount of memory for two-electron integrals is reduced to three-eigths by Kramers restriction. The algorithm is applied to the d−d excitation energies of the platinum halide complexes, [PtCl4]2−, [PtBr4]2−, and [PtCl6]2−and to the 6p−7s and 6p−7p excitation energies of the radon atom. It is shown to provide high parallelization efficiency and accurate excitation energies that agree well with experimental data.

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 π 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.

A phosphorus-containing hybrid porphyrin was successfully prepared via the BF3-promoted dehydrative condensation between 4-phosphatripyrrane and 2,5-bishydroxy(phenyl)methylthiophene. The NMR and UV-vis absorption spectra, electrochemical measurements, and DFT calculations revealed that the 3-P,N2,S-hybrid porphyrin exhibits high aromaticity as an 18-electron system in terms of both geometric and magnetic criteria.

The second‐order multireference perturbation theory using an optimized partitioning, denoted as MROPT(2), is applied to calculations of various molecular properties—excitation energies, spectroscopic parameters, and potential energy curves—for five molecules: ethylene, butadiene, benzene, N2, and O2. The calculated results are compared with those obtained with second‐ and third‐order multireference perturbation theory using the traditional partitioning techniques. We also give results from computations using the multireference configuration interaction (MRCI) method. The presented results show very close resemblance between the new method and MRCI with renormalized Davidson correction. The accuracy of the new method is good and is comparable to that of second‐order multireference perturbation theory using Møller‐Plesset partitioning. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 1390–1400, 2003

The quasi‐degenerate perturbation theory (QDPT) with complete active space (CAS) self‐consistent field (SCF) reference functions is extended to the general multiconfiguration (MC) SCF references functions case. A computational scheme that utilizes both diagrammatic and sum‐over‐states approaches is presented. The second‐order effective Hamiltonian is computed for the external intermediate configurations (including virtual or/and core orbitals) by the diagrammatic approach and for internal intermediate configurations (including only active orbitals) by the configuration interaction matrix‐based sum‐over‐states approach. The method is tested on the calculations of excitation energies of H2O, potential energy curves of LiF, and valence excitation energies of H2CO. The results show that the present method yields very close results to the corresponding CAS‐SCF reference QDPT results and the available experimental values. The deviations from CAS‐SCF reference QDPT values are less than 0.1 eV on the average for the excitation energies of H2O and less than 1 kcal/mol for the potential energy curves of LiF. In the calculation of the valence excited energies of H2CO, the maximum deviation from available experimental values is 0.28 eV. © 2002 Wiley Periodicals, Inc. J Comput Chem 23: 1166–1175, 2002

The quasi-degenerate perturbation theory (QDPT) with complete active space (CAS) self-consistent field (SCF) reference functions is extended to the general multiconfiguration (MC) SCF references functions case. A computational scheme that utilizes both diagrammatic and sum-over-states approaches is presented. The second-order effective Hamiltonian is computed for the external intermediate configurations (including virtual or/and core orbitals) by the diagrammatic approach and for internal intermediate configurations (including only active orbitals) by the configuration interaction matrix-based sum-over-states approach. The method is tested on the calculations of excitation energies of H2O, potential energy curves of LiF, and valence excitation energies of H2CO. The results show that the present method yields very close results to the corresponding CAS-SCF reference QDPT results and the available experimental values. The deviations from CAS-SCF reference QDPT values are less than 0.1 eV on the average for the excitation energies of H2O and less than 1 kcal/mol for the potential energy curves of LiF. In the calculation of the valence excited energies of H2CO, the maximum deviation from available experimental values is 0.28 eV. © 2002 Wiley Periodicals, Inc. J Comput Chem 23: 1166–1175, 2002

An algorithm for computing electron repulsion integrals (ERIs) oriented to the general contraction scheme is presented. The accompanying coordinate expansion (ACE) method of Ishida is utilized to derive an efficient algorithm. The performance estimated with the floating-point operation (FLOP) count is about N² times and more as efficient as the conventional algorithm for the segmented contraction scheme, where N indicates the number of contracted Gaussian-type orbitals (GTOs) contained in a set of generally contracted GTOs. The efficiency is also confirmed by using a realistic molecular system, the benzene molecule, with C:14s9p/3s2p, H:8s4p/2s1p, and C:14s9p/6s5p, H:8s4p/4s3p basis sets. The measured central processing unit (CPU) time is in good agreement with the FLOP count estimation. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 76: 396–406, 2000

A study of FeCO+ and Fe+ using both the second-order multi-configurational quasi-degenerate perturbation theory (MC-QDPT2) method and the coupled cluster theory with single and double replacements (augmented by perturbative triples) [CCSD(T)] method are presented. An all-electron triple-ζ valence plus polarization basis set was used in all calculations. The equilibrium CCSD(T) geometry of FeCO+ is found to be linear (4Σ-) with a Fe+ to CO distance of 1.905 Å and a CO bond distance of 1.133 Å. The dissociation energy D0 of 4Σ- FeCO+ to 6D Fe+ and 1Σ+ CO is predicted to be 28.8 kcal mol-1, which is within the experimental range. Excited state properties including potential energy surfaces and De are predicted for the low lying sextet and quartet states of FeCO+. The first excited state is predicted to be 4Δ with a De of 17.6 kcal mol-1. The lowest sextet state is predicted to be 6Δ with a D0 of 12.3 kcal mol-1. Several examples of pathological behavior at many levels of theory have been discovered and are discussed.

Abstract.: The valence π → π * excited states of anthracene and naphthacene are studied with multireference perturbation theory with complete active space self-consistent field reference functions. The predicted spectra provide a consistent assignment of all one- and two-photon spectra and T-T spectra of low-lying valence π → π * excited states of anthracene and naphthacene. The present theory predicts the valence π → π * excitation energies with an accuracy of 0.15 eV for anthracene and of 0.25 eV or better for naphthacene. The excited states of anthracene and naphthacene are compared with those of benzene and naphthalene studied previously. The present calculations predict that, going from anthracene to naphthacene, there is a symmetry reversal of the two lowest singlet state transitions, but not for the triplet, just as indicated by the experimental data. Some general trends of polyacene excited states are discussed based on the calculated results for benzene to naphthacene. Conclusive results obtained for anthracene and naphthacene can be used as a model for understanding the excited states of larger polyacenes.

Summary It is proposed to use a norm of anth order effective Hamiltonian, for analyzing the convergence property of the multireference many-body perturbation theory (MR-MBPT). The utilization of the norm allows us to employ only (1) asingle number for all the states that we are interested in, and (2) values which decreases from thepositive side to zero as the ordern of the perturbation increases. This characteristic features are in contrast to those in the usually used scheme whereseveral numbers, namely, the eigenvalues of the target states, should be used and they mayoscillate around exact eigenvalues. The present method has been applied to MR-MBPT calculations of the (H2)2, CH2, and LiH molecules based on the multireference versions of Rayleigh-Schrödinger PT, Kirtman-Certain-Hirschfelder PT, and the canonical Van Vleck PT; and following features are found: (1) the above three versions of the perturbation theories have essentially the same convergence property judged from the lowering of the norm; (2) the lower order truncation of the perturbation series gives reasonable solutions; (3) the norm decreases irrespective of the perturbation expansion being convergent or divergent for the first several orders (up to about the sixth order).

Multireference perturbation theory with complete active space self-consistent field (CASSCF) reference functions is applied to the study of the valence π→π* excited states of 1,3-butadiene, 1,3,5-hexatriene, 1,3,5,7-octatetraene, and 1,3,5,7,9-decapentaene. Our focus was put on determining the nature of the two lowest-lying singlet excited states, 1¹Bu⁺ and 2¹Ag⁻, and their ordering. The 1¹Bu⁺ state is a singly excited state with an ionic nature originating from the HOMO→LUMO one-electron transition while the covalent 2¹Ag⁻ state is the doubly excited state which comes mainly from the (HOMO)²→(LUMO)² transition. The active-space and basis-set effects are taken into account to estimate the excitation energies of larger polyenes. For butadiene, the 1¹Bu⁺ state is calculated to be slightly lower by 0.1 eV than the doubly excited 2¹Ag⁻ state at the ground-state equilibrium geometry. For hexatriene, our calculations predict the two states to be virtually degenerate. Octatetraene is the first polyene for which we predict that the 2¹Ag⁻ state is the lowest excited singlet state at the ground-state geometry. The present theory also indicates that the 2¹Ag⁻ state lies clearly below the 1¹Bu⁺ state in decapentaene with the energy gap of 0.4 eV. The 0–0 transition and the emission energies are also calculated using the planar C2h relaxed excited-state geometries. The covalent 2¹Ag⁻ state is much more sensitive to the geometry variation than is the ionic 1¹Bu⁺ state, which places the 2¹Ag⁻ state significantly below the 1¹Bu⁺ state at the relaxed geometry. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 66: 157–175, 1998

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. 1H 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.

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