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The charge-transfer (CT) excited state of FHCl (F+H–Cl−), generated by the photodetachment of an electron from its precursor anion (FHCl−) by a photon energy of ∼9.5 eV, is a realistic prototype of two bidirectional-coupled reaction pathways, namely the proton-transfer (PT) and electron-transfer (ET) channels, that produce F + HCl and FH + Cl combinations, respectively. The early-time dynamics of the CT was studied via the time-dependent propagations of nuclear wave packets comprising three nonadiabatically coupled electronic states defined within a three-dimensional space. The detailed analyses of the early-time dynamics revealed an interesting phenomenon in which the onset of PT was ∼80 fs earlier than that of ET, indicating that PT dominated ET in this case. A more significant finding was that the proper adjustment of the electronic-charge distribution for the onset of ET was obtained ∼80 fs after the onset of PT; this adjustment was mediated by the initial movement of the H atom, i.e., the F–H vibration mode. To avail experimental observables, the branching ratio, χ = PT/(PT + ET), and absorption spectrum generating the neutral FHCl molecule from its precursor anion were also simulated. The results further demonstrated the dependences of the χs and spectrum on the change in the initial vibration level of the precursor anion, as well as the isotopic substitution of the connecting H atom with deuterium, tritium, and muonium. [ABSTRACT FROM AUTHOR]

A charge-transfer (CT) excited state of NH3Cl, generated by photo-detachment of an electron from the anionic NH3Cl− precursor, can be represented as H2N+–H–Cl− and proceeds to two chemical reactions: one reaction generating NH2 and HCl resulting from a proton transfer (PT) and the other reaction producing NH3 and a Cl atom resulting from an electron transfer (ET); both are coupled to form a typical proton-coupled electron transfer (PCET) process. The early time dynamics of this CT were studied using time-dependent wavepacket propagation on three nonadiabatically coupled electronic states in a reduced three-dimensional space. The electronic states were treated using the XMS-CASPT2/aug-cc-pVTZ ab initio methodology. The population dynamics of the three coupled electronic states were analyzed in detail to reveal the initial stage of the PCET process up to ∼100 fs, while the branching ratio, χ = PT/(ET+PT), was determined after wavepacket propagations of up to 2000 fs. Another main result is the dependence of χ on the vibration levels of the initial precursor anion and the isotope substitution of the connecting H atom with deuterium and tritium. Our study reveals the detailed microscopic features of the PCET process embedded in the CT state of the NH3Cl complex and certain systematic dependences of the branching ratio χ on the above factors. [ABSTRACT FROM AUTHOR]

To augment previous theoretical studies of thermochemical properties such as the electron affinity (EA) and bond dissociation enthalpy ( D 298 o ) of neutral and anionic SFn (with n = 1–6), further extensive theoretical computations using Gaussian-4 and Weizmann-1 and Weizmann-2 (G4/W1/W2) methods were carried out with extensive consideration of the role of the metastable conformational isomer of the S F 4 − anion. The energy of the metastable conformer is 39 kJ/mol higher than that of the global minimum structure, and the barrier height between the metastable conformer and its global minimum was calculated to be 27 kJ/mol by the CCSD(T)/Aug-cc-pvQZ+d//MP2/cc-pvQZ+d method. Many of the discrepancies that have persisted between previous theoretical and experimental data can be explained more adequately by considering the metastable conformer. The difference in the EA calculated using the Gaussian-3 (G3) vs the W2 method for SFn with n = 2–6 ranges from 0.12 eV to 0.21 eV, which is much larger than ±0.041 eV of the expected error for the G3 method. The difference in D 298 o calculated using G3 vs W2 was also significant in several cases, especially for hypervalent fluorides with n = 3–6. The final results obtained with the W2 procedure are sufficiently converged to a chemical accuracy of ±4 kJ/mol ≈ ±0.04 eV for not only the EA but also D 298 o , for all neutral and anionic SFn species with n = 1–6. [ABSTRACT FROM AUTHOR]

The photodissociation dynamics of methylamines (CH3NH2 and CD3ND2) on the first electronically excited state has been investigated using the velocity map ion imaging technique probing the H or D fragment. Two distinct velocity components are found in the H(D) translational energy distribution, implying the existence of two different reaction pathways for the bond dissociation. The high H(D) velocity component with the small internal energy of the radical fragment is ascribed to the N–H(D) fragmentation via the coupling of S1 to the upper-lying S2 repulsive potential energy surface along the N–H(D) bond elongation axis. Dissociation on the ground S0 state prepared via the nonadiabatic dynamics at the conical intersection should be responsible for the slow H(D) fragment. Several S1 vibronic states of methylamines including the zero-point level and nν9 states (n=1, 2, or 3) are exclusively chosen in order to explore the effect of the initial quantum content on the chemical reaction dynamics. The branching ratio of the fast and slow components is found to be sensitive to the initial vibronic state for the N–H bond dissociation of CH3NH2, whereas it is little affected in the N–D dissociation event of CD3ND2. The fast component is found to be more dominant in the translational distribution of D from CD3ND2 than it is in that of H from CH3NH2. The experimental result is discussed with a plausible mechanism of the conical intersection dynamics. [ABSTRACT FROM AUTHOR]

The low-lying electronic states of Ag[sub 3][sup -]([sup 1]Σ[sub g][sup +],[sup 3]B[sub 2]), Ag[sub 3]([sup 2]B[sub 2],[sup 2]A[sub 1],[sup 2]B[sub 1],[sup 4]B[sub 2],[sup 2]Σ[sub u][sup +],1 [sup 2]Σ[sub g][sup +],2 [sup 2]Σ[sub g][sup +],[sup 2]Π[sub u],[sup 4]Σ[sub u][sup +]), and Ag[sub 3][sup +]([sup 1]A[sub 1],[sup 1]Σ[sub g][sup +],[sup 3]Σ[sub u][sup +],[sup 3]A[sub 1]) are studied by ab initio calculations with the Stuttgart effective core potentials and corresponding (8s7p6d)/[6s5p3d] and (8s7p5d3f )/[6s5p3d3f] basis sets. The geometries, vibrational frequencies, and energetic splittings are obtained by the coupled-cluster method including singles and doubles (CCSD) and those including up to the noniterative triples [CCSD(T)] correlation methods with additional frozen core molecular orbitals corresponding to 4s and 4p orbitals. The results for well-studied states (Ag[sub 3][sup -] [sup 1]Σ[sub g][sup +];Ag[sub 3] [sup 2]B[sub 2],[sup 2]A[sub 1],[sup 2]Σ[sub u][sup +];Ag[sub 3][sup +] [sup 1]A[sub 1]) are in good agreement with previous experimental results, and therefore our results for other newly studied states are expected to be reliable. The vertical detachment energies of Ag[sub 3][sup -] are obtained by the electron excitation equation-of-motion coupled-cluster (EE-EOM-CCSD) method and the average deviation from the experimental results is small without any scaling correction of the obtained values. The effect of the f-functions in the basis sets and the noniterative triples in the CCSD(T) method is discussed; the bond lengths are reduced significantly and the vertical detachment energies and ionization potentials are in much better agreement with experiment. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The electron diffraction patterns of s-tetrazine in specific electronic and vibrational states are calculated. The differences in diffraction patterns of isoenergetic vibrational states provide an opportunity for observing the flow of vibrational energy through the phase space by time-dependent three-dimensional mapping.

The reactions of [Pd(olefin)(PR3)2] (PR3 = PMe3, PMe2Ph) with two equivalents of an aryl or alkyl isocyanate afford cis-[Pd{–N(R)C(O)N(R)C(O)–}(PR3)2] (R = 1-naphthyl, 4-phenoxyphenyl), which are five-membered palladacycles bearing dimeric isocyanate units, or cyclic tetramers as assemblies of four five-membered palladacycles, [Pd{C(O)N(R′)C(O)N(R′)}(PMe3)]4, (R′ = 3-methylbenzyl, 4-methylbenzyl or 4-methoxybenzyl), depending on the alkyl substituent on R-NCO. Interestingly, these reactions afford cyclic trimers as catalytic products when two equivalents or excess amounts of benzyl isocyanate are used. In contrast, reactions of [Pt(olefin)(PR3)2] with two equivalents of an alkyl or aryl isocyanate afford only the five-membered platinacycle, namely cis-[Pt{–N(R)C(O)N(R)C(O)–}(PMe3)2] (R = 3-methylbenzyl, 4-methylbenzyl, 4-fluorobenzyl, 4-methoxybenzyl, (S)-(+)-(1-naphthyl)ethyl, (R)-(−)-(1-naphthyl)ethyl, 4-phenoxyphenyl and 2,6-difluorophenyl). Aided by theoretical calculations, we propose mechanisms for the formation of the five-membered palladacycle or platinacycle, the cyclic tetramer, and the cyclotrimerization of the organic isocyanate. In addition, the ligand-exchange reactions between a five-membered platinacycle bearing a chiral substituent such as (S)-(+)-(1-naphthyl)ethyl or (R)-(−)-(1-naphthyl)ethyl) moieties and 1,2-bis(diethylphosphino)ethane (DEPE), a chelating phosphine, clearly afford the corresponding platinacycle bearing a DEPE ligand with retention of chirality. On the other hand, reactions of [Ni(COD)2] with various organic isocyanates in the presence of tertiary phosphines only afford the corresponding cyclic trimers. In contrast, similar reactions in the presence of N-heterocyclic carbenes (NHC) such as 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) or 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2-ylidine (SIPr) afford unexpected adducts between R-NCO and the NHC ligand. [ABSTRACT FROM AUTHOR]

All-electron relativistic self-consistent-field (RSCF) method based upon Dirac–Coulomb Hamiltonian is extended to include the magnetic part of the Breit interaction term in the SCF cycle. The explicit form of the Fock matrix for the magnetic part is derived and simplified within the restricted open-shell scheme. The effects of the magnetic part of the Breit term on spin–orbit splittings and dipole moments are investigated for 2Π states of diatomic hydrides AH (A=Be,B,C,N,O,F,Mg,Al,Si,P,S). Calculated spin–orbit splittings are improved significantly by the inclusion of the magnetic part and approach the experimental values to within 10 cm-1 even for the second-row diatomic hydrides. The magnitude of the effect of the magnetic part is similar for the molecules composed of atoms in the same group regardless of the nuclear charge implying that the magnetic part and probably the whole Breit term become less important for molecules with large spin–orbit interactions. With the present RSCF method, the effects of magnetic term on properties can be estimated from expectation values. The effects of the magnetic term on dipole moments of 2Π states of AH molecules are quite small. [ABSTRACT FROM AUTHOR]

Examines the low-lying electronic states of Al[sub 3] and Al[sup -][sub 3] through coupled-cluster methods. Calculation of geometries and harmonic frequencies by coupled-cluster single double triple correlation method; Analysis of processes of ionizations and vibronic transitions; Details on anticipated features of other electronic excitations.

Reports on the systematic study of the magnitude and trends of the effects of frozen molecular orbitals in coupled-cluster and many-body perturbation theory methods. Theoretical considerations and implementations; Effects of core correlation on geometry and vibrational frequencies.

Describes the structures, vibrational frequencies, ionization potentials, electron affinities and excited states of the boron trichloride plasma. Calculation of the excited, electron attached and ionized states by employing the equation-of-motion coupled cluster method; Features of the potential energy surfaces of excited states of boron trichloride.

A brief background on the quantum wave-packet propagation method for the study of photodissociation dynamics of polyatomic molecules is summarized as a short tutorial review. The main emphasis is on reasons to use the wave-packet propagation method, followed by a description about basic considerations for practical application of the wave-packet method to polyatomic molecules. The considerations are divided into six steps in the following sequence: (1) prerequisite information for related states, (2) search for critical points, (3) selection of coordinates and kinetic energy operator, (4) potential energy surface, (5) propagation of wave-packet, and (6) analysis of the propagated results. Limitations of the present review and a very brief perspective are given as concluding remarks. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

ABSTRACT We present a fully transparent nonvolatile resistive polymer memory device based on an anthracene-containing partially aliphatic polyimide along with indium tin oxide (ITO) top and bottom electrodes. High transmittance of over 90% in the wavelength range of 400 to 800 nm is accomplished with an ITO/polyimide/ITO/glass device. The device shows unipolar write-once-read-many times (WORM) memory behavior with an ON/OFF current ratio of ∼2 × 103, and the ratio remained without any significant degradation for over 104 s. The memory behavior of the device is considered to be governed by trap-controlled space-charge limited conduction (SCLC) and local filament formation. Based on molecular simulation of the polyimide, the location of energy states is different from that in the conventional charge transfer (CT) mechanism. Despite the relatively low ON/OFF current ratio, our results can give insight into the development of fully transparent memory device. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 918-925 [ABSTRACT FROM AUTHOR]

Abstract: A synthesis of the E-isomer of the proposed structure of the novel tripeptide, lucentamycin A, was performed in an attempt to define the correct stereochemistry of this natural product. The synthetic route developed employs a stereoselective Rh-catalyzed reductive cyclization process to generate the key pyrrolidine residue in the target and a stereospecific inversion of the Z-olefin geometry to form desired E-isomer. Subsequent amide coupling reactions afforded the desired E-isomer of putative lucentamycin A. A comparison of the NMR data of synthetic E-1a with that of the naturally occurring lucentamycin A demonstrated that they are not identical substances and the E -1a was found to display no anti-proliferative activity on the colon cancer cell line HCT-116 in contrast to natural lucentamycin A. [Copyright &y& Elsevier]

The low-lying electronic states of carbonyl chlorofluoride (ClFCO) were studied using the coupled-cluster singles and doubles (CCSD) method. Highly reliable values for not only the geometrical parameters, but also the vibrational properties were generated for T1 and S1 as well as S0. Potential energy surfaces (PESs) of the dissociation of the three bonds were also obtained for each electronic state separately. We found that the T1 and S1 states are both vibrationally predissociative along the C-Cl bond dissociation channel, with barrier heights of only 0.13 and 0.23 eV, respectively. The relative energies for the S1 state of the barriers to C-Cl and C-F bond dissociation are 4.93 and 6.13 eV, respectively, with respect to S0. These results suggest that a simple C-Cl bond dissociation pathway can explain the results of a previous photodissociation experiment with 235 nm (5.276 eV) light, in which only 'Cl + FCO' fragments were observed. [ABSTRACT FROM AUTHOR]

Abstract: Noble metal nanocatalysts such as Pd, Pt, and Au were strongly immobilized on the inside walls of monolithic honeycomb-structured cordierite, in which bi-functional molecules were used as linkers for anchoring noble metal nanoparticles (NPs) on the cordierite surface. The supported nanocatalysts were characterized by ICP-MS, TEM, and X-ray powder diffraction. The efficiencies of the immobilized nanocatalysts for the removal of harmful nitrogen oxides (NO x ) have been investigated by measuring the deNO x capability as a function of temperature. The catalytic activities depend mainly on the compositions of the nanocatalysts. The Pd/Pt bi-metal catalyst anchored on the cordierite surface shows higher NO x conversion and better activity than the commercial emission catalyst at low temperature region, which could be due to the large portion of active surface areas of the catalysts with nanometer scale. [Copyright &y& Elsevier]

Treatment with isoprenaline led to a change in the cell morphology of rat C6 glioma cells. This morphological change was reverted by the addition of sphingosine 1-phosphate (S1P). Using this morphological change as a response marker we determined that DS-SG-44 ((2S,3R)-2-amino-3-hydroxy-4-(4-octylphenyl)butyl phosphoric acid) was an agonist of S1P receptors. The DS-SG-44-induced morphological reversion was not observed with such structurally related molecules as DS-SG-45 ((2S,3R)-2-amino-3-hydroxy-4-(3-octylphenyl)butyl phosphoric acid) and DS-SG-12 ((2S,3R)-2-amino-4-(4-octylphenyl)butane-1,3-diol). The S1P- and DS-SG-44-induced shape changes were nseither reproduced with the S1P1/S1P3 receptor agonist VPC24191 nor inhibited by the S1P1/S1P3 receptor antagonist, VPC23019. Transfection with small interfering RNA (siRNA) for the S1P2 receptor greatly inhibited the DS-SG-44-induced shape change, and in part an S1P-induced response. In the presence of VPC23019, siRNA transfection for the S1P2 receptor almost completely blocked the S1P- and DS-SG-44-induced shape changes. Our results suggested that DS-SG-44, a newly-synthesized S1P analogue, acted as an S1P receptor agonist and that the S1P-induced shape change in rat C6 glioma cells was mediated mainly through the S1P2 receptor, and cooperatively through the S1P1/S1P3 receptors. [ABSTRACT FROM AUTHOR]

An efficient and highly stereoselective synthesis of D-ribo-(2S,3S,4R)-phytosphingosine was accomplished in 62% overall yield starting from commercially available (2S)-hydroxymethylaziridine via osmium-catalyzed asymmetric dihydroxylation as a key step. [ABSTRACT FROM AUTHOR]

The analytic gradient method for the equation-of-motion coupled-cluster (EOM-CC) energy has been extended to employ a reduced molecular orbital (MO) space. The geometrical and the vibrational properties of the first excited singlet state of formaldehyde have been studied by using several different sizes of dropped MO space. It is shown that reliable results can be produced with high efficiency by employing the EOM-CC with a reduced MO space, which provides a new hierarchy in the study of photochemical processes in molecules. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Abstract: In order to find a density functional theory (DFT) method appropriate to perfluorocarbon molecules (PFCs), the properties of three isomeric forms of C4F8 were calculated, with special emphasis on the ring-puckering angle (δ), electron affinity (EA), and the inversion barriers to the ring-puckering (ΔE RP) of and the trans-to-cis isomerization (ΔE iso) of . It was shown that reliable calculations of the EAs of the PFCs require that at least one set of f functions be added to the split valence-shell type and diffuse basis functions. Our analysis of the calculated values recommends the ωB97X-D/aVTZ method for future studies of other PFC systems. Examination of the trans-to-cis isomerization of the neutral 2-C4F8 and anionic systems revealed that the transition state of the neutral form (TSiso) is symmetric but that its anionic counterpart () is asymmetric in both geometry and charge distribution. This asymmetry corresponds to a kind of electronic charge flow from one side of to the other. The reason for the lower energy barrier of the isomerization of the anion than that of the neutral form is also discussed. [Copyright &y& Elsevier]

A very simple equation, F ij App =[(∂ 2 (V i a -V j a )/∂Q 2 )/(V i a -V j a )] 1/2 /2, giving a reliable magnitude of non-adiabatic coupling terms (NACTs, F ij 's) based on adiabatic potential energies only (V i a and V j a ) was discovered, and its reliability was tested for several prototypes of same-symmetry interstate crossings in LiF, C 2 , NH 3 Cl, and C 6 H 5 SH molecules. Our theoretical derivation starts from the analysis of the relationship between the Lorentzian dependence of NACTs along a diabatization coordinate and the well-established linear vibronic coupling scheme. This analysis results in a very simple equation, α=2κ/Δ c , enabling the evaluation of the Lorentz function α parameter in terms of the coupling constant κ and the energy gap Δ c (Δ c =|V i a -V j a | Q c ) between adiabatic states at the crossing point Q C . Subsequently, it was shown that Q C corresponds to the point where F ij App exhibit maximum values if we set the coupling parameter as κ=[(V i a -V j a )⋅(∂ 2 (V i a -V j a )/∂Q 2 )] Q c 1/2 /2. Finally, we conjectured that this relation could give reasonable values of NACTs not only at the crossing point but also at other geometries near Q C . In this final approximation, the pre-defined crossing point Q C is not required. The results of our test demonstrate that the approximation works much better than initially expected. The present new method does not depend on the selection of an ab initio method for adiabatic electronic states but is currently limited to local non-adiabatic regions where only two electronic states are dominantly involved within a nuclear degree of freedom.

A fixed relation of α × β = 1.397 between the α- and β-parameters of a Lorentz function and a Laplace function that approximates nonadiabatic coupling terms and maximizes the overlap area between the two functions was found. The mixing angle corresponding to the geometric average between the potential couplings calculated using the individual path-integral of the two functions was then used in the construction of diabatic states and the coupling of the states. Employing the new method, the actual computation of nonadiabatic coupling terms at just a few geometries before and after the guessed conical intersection is enough, and the remaining steps are straightforward and almost automatic. The new method was tested for the one-dimensional LiF system and the two-dimensional space of the collinear case of NH3Cl, and promising results were achieved.

Rigorous quantum dynamical study of concerted proton-coupled electron transfer (PCET) on the time scale of a few femtoseconds (fs) has been rarely reported. Herein, a time-dependent quantum wavepacket propagation method was applied to the dynamics of the charge-transfer excited electronic state of FHCl corresponding to F(+)HCl(-). The dynamics corresponds to a bidirectional PCET with two dissociation channels: the electron transfer (ET, generating FH+Cl) and proton transfer (PT, generating F+HCl) paths. The calculated branching ratio (Cl/F), 0.78, implies a surprising fact: PT prevails over ET. A detailed analysis of the proton movement and electron readjustment suggests that the proton movement starts ∼3 fs earlier than the electron movement, and the electron readjustment is triggered by the initial movement of the proton. The branching ratio drastically inverts to 1.24 because of a reduced nonadiabatic effect in the isotope-substituted system, FDCl.

An earlier time-dependent quantum wave packet propagation study of the photochemistry of Ph-OH [J. Chem. Phys. 2005, 122, 224315] is extended to investigate isotope effects (for Ph-OD) and the dynamics initiated by direct (vibronically induced) excitation to the (1)πσ* state. The isotope effect is significant only when the initially excited state is (1)ππ*, that is, there are noticeable changes not only in the time scale but also in the branching ratio (Ã/X̃) for the electronic states of the product Ph-O radical. In contrast, the isotope effect on the dynamics initiated by direct excitation to the (1)πσ* state is very small. Our most important observation for the dynamics initiated by direct excitation to the (1)πσ* state is that the initial excitation of the O-H stretch mode does not result in a noticeable enhancement of the product Ph-O radical in the à state, which corresponds to a dissociating H atom with low kinetic energy. The initial excitation of the CCOH torsion mode is the main reason for the enhancement of the product Ph-O radical in the à state that was observed in a vibrationally mediated two-photon experiment [J. Chem. Phys.2008, 128, 104307].