Mononuclear Carbonyl Anion Complexes of Groups Ⅳ and Ⅴ Metals

The anionic carbonyl complexes of groups IV and V metals TM(CO)\begin{document}$ _{6,7} $\end{document} (TM=Ti, Zr, Hf, V, Nb, Ta) are prepared in the gas phase using a laser vaporation-supersonic expansion ion source. The infrared spectra of TM(CO)\begin{document}$ _{6,7} $\end{document}\begin{document}$ ^- $\end{document} anion complexes in the carbonyl stretching frequency region are measured by mass-selected infrared photodissociation spectroscopy. The six-coordinated TM(CO)\begin{document}$ _6 $\end{document}\begin{document}$ ^- $\end{document} anions are determined to be the coordination saturate complexes for both the group IV and group V metals. The TM(CO)\begin{document}$ _6 $\end{document}\begin{document}$ ^- $\end{document} complexes of group IV metals (TM=Ti, Zr, Hf) are 17-electron complexes having a \begin{document}$ ^2 $\end{document}A\begin{document}$ _{\rm{1g}} $\end{document} ground state with \begin{document}$ D_{\rm{3d}} $\end{document} symmetry, while the TM(CO)\begin{document}$ _6 $\end{document}\begin{document}$ ^- $\end{document} complexes of group V metals (TM=V, Nb, Ta) are 18-electron species with a closed-shell singlet ground state possessing \begin{document}$ O_{\rm{h}} $\end{document} symmetry. The energy decomposition analyses indicate that the metal-CO covalent bonding is dominated by TM\begin{document}$ ^- $\end{document}(d)\begin{document}$ \rightarrow $\end{document}(CO)\begin{document}$ _6 $\end{document} \begin{document}$ \pi $\end{document}-backdonation and TM\begin{document}$ ^- $\end{document}(d)\begin{document}$ \leftarrow $\end{document}(CO)\begin{document}$ _6 $\end{document} \begin{document}$ \sigma $\end{document}-donation interactions.     

Photochemistry of Potassium Ferrocyanide and its Reaction with Uridine 5′-monophosphate in Aqueous Solution under Ultraviolet Irradiation

The photochemical reaction of potassium ferrocyanide (K\begin{document}$ _4 $\end{document}Fe(CN)\begin{document}$ _6 $\end{document}) exhibits excitation wavelength dependence and non-Kasha rule behavior. In this study, the excited-state dynamics of K\begin{document}$ _4 $\end{document}Fe(CN)\begin{document}$ _6 $\end{document} were studied by transient absorption spectroscopy. Excited state electron detachment (ESED) and photoaquation reactions were clarified by comparing the results of 260, 320, 340, and 350 nm excitations. ESED is the path to generate a hydrated electron (e\begin{document}$ _{\rm{aq}}^{-} $\end{document}). ESED energy barrier varies with the excited state, and it occurs even at the first singlet excited state (\begin{document}$ ^{1} $\end{document}T\begin{document}$ _{\rm{1g}} $\end{document}). The \begin{document}$ ^{1} $\end{document}T\begin{document}$ _{\rm{1g}} $\end{document} state shows \begin{document}$ {\sim} $\end{document}0.2 ps lifetime and converts into triplet [Fe(CN)\begin{document}$ _{6} $\end{document}]\begin{document}$ ^{4-} $\end{document} by intersystem crossing. Subsequently, \begin{document}$ ^{3} $\end{document}[Fe(CN)\begin{document}$ _{5} $\end{document}]\begin{document}$ ^{3-} $\end{document} appears after one CN\begin{document}$ ^{-} $\end{document} ligand is ejected. In sequence, H\begin{document}$ _{2} $\end{document}O attacks [Fe(CN)\begin{document}$ _{5} $\end{document}]\begin{document}$ ^{3-} $\end{document} to generate [Fe(CN)\begin{document}$ _{5} $\end{document}H\begin{document}$ _{2} $\end{document}O]\begin{document}$ ^{3-} $\end{document} with a time constant of approximately 20 ps. The \begin{document}$ ^{1} $\end{document}T\begin{document}$ _{\rm{1g}} $\end{document} state and e\begin{document}$ _{\rm{aq}}^{-} $\end{document} exhibit strong reducing power. The addition of uridine 5\begin{document}$ ' $\end{document}-monophosphate (UMP) to the K\begin{document}$ _{4} $\end{document}Fe(CN)\begin{document}$ _{6} $\end{document} solution decrease the yield of e\begin{document}$ _{\rm{aq}}^{-} $\end{document} and reduce the lifetimes of the e\begin{document}$ _{\rm{aq}}^{-} $\end{document} and \begin{document}$ ^{1} $\end{document}T\begin{document}$ _{\rm{1g}} $\end{document} state. The obtained reaction rate constant of \begin{document}$ ^{1} $\end{document}T\begin{document}$ _{\rm{1g}} $\end{document} state and UMP is 1.7\begin{document}$ {\times} $\end{document}10\begin{document}$ ^{14} $\end{document} (mol/L)\begin{document}$ ^{-1}\cdot $\end{document}s\begin{document}$ ^{-1} $\end{document}, and the e\begin{document}$ _{\rm{aq}}^{-} $\end{document} attachment to UMP is \begin{document}$ {\sim} $\end{document}8\begin{document}$ {\times} $\end{document}10\begin{document}$ ^{9} $\end{document} (mol/L)\begin{document}$ ^{-1}\cdot $\end{document}s\begin{document}$ ^{-1} $\end{document}. Our results indicate that the reductive damage of K\begin{document}$ _{4} $\end{document}Fe(CN)\begin{document}$ _{6} $\end{document} solution to nucleic acids under ultraviolet irradiation cannot be neglected.     

Theoretical Investigations on Photodissociation Dynamics of Deuterated Alkyl Halides CD3CH2F

The product branching ratio between different products in multichannel reactions is as important as the overall rate of reaction, both in terms of practical applications (\emph{e.g}. models of combustion or atmosphere chemistry) in understanding the fundamental mechanisms of such chemical reactions. A global ground state potential energy surface for the dissociation reaction of deuterated alkyl halide CD\begin{document}$ _3 $\end{document}CH\begin{document}$ _2 $\end{document}F was computed at the CCSD(T)/CBS//B3LYP/aug-cc-pVDZ level of theory for all species. The decomposition of CD\begin{document}$ _3 $\end{document}CH\begin{document}$ _2 $\end{document}F is controversial concerning C\begin{document}$ - $\end{document}F bond dissociation reaction and molecular (HF, DF, H\begin{document}$ _2 $\end{document}, D\begin{document}$ _2 $\end{document}, HD) elimination reaction. Rice-Ramsperger-Kassel-Marcus (RRKM) calculations were applied to compute the rate constants for individual reaction steps and the relative product branching ratios for the dissociation products were calculated using the steady-state approach. At the different energies studied, the RRKM method predicts that the main channel for DF or HF elimination from 1, 2-elimination of CD\begin{document}$ _3 $\end{document}CH\begin{document}$ _2 $\end{document}F is through a four-center transition state, whereas D\begin{document}$ _2 $\end{document} or H\begin{document}$ _2 $\end{document} elimination from 1, 1-elimination of CD\begin{document}$ _3 $\end{document}CH\begin{document}$ _2 $\end{document}F occurs through a direct three-center elimination. At 266, 248, and 193 nm photodissociation, the main product CD\begin{document}$ _2 $\end{document}CH\begin{document}$ _2 $\end{document}+DF branching ratios are computed to be 96.57%, 91.47%, and 48.52%, respectively; however, at 157 nm photodissociation, the product branching ratio is computed to be 16.11%. Based on these transition state structures and energies, the following photodissociation mechanisms are suggested: at 266, 248, 193 nm, CD\begin{document}$ _3 $\end{document}CH\begin{document}$ _2 $\end{document}F\begin{document}$ \rightarrow $\end{document}absorption of a photon\begin{document}$ \rightarrow $\end{document}TS5\begin{document}$ \rightarrow $\end{document}the formation of the major product CD\begin{document}$ _2 $\end{document}CH\begin{document}$ _2 $\end{document}+DF; at 157 nm, CD\begin{document}$ _3 $\end{document}CH\begin{document}$ _2 $\end{document}F\begin{document}$ \rightarrow $\end{document}absorption of a photon\begin{document}$ \rightarrow $\end{document}D/F interchange of TS1\begin{document}$ \rightarrow $\end{document}CDH\begin{document}$ _2 $\end{document}CDF\begin{document}$ \rightarrow $\end{document}H/F interchange of TS2\begin{document}$ \rightarrow $\end{document}CHD\begin{document}$ _2 $\end{document}CHDF\begin{document}$ \rightarrow $\end{document}the formation of the major product CHD\begin{document}$ _2 $\end{document}+CHDF.     

Gamma Ray Radiation Effect on \begin{document}$\rm{{Bi}}_{2}$\end{document}W\begin{document}$\rm{{O}}_{6}$\end{document} Photocatalyst

The development of \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document}-based materials has become one of research hotspots due to the increasing demands on high-efficient photocatalyst responding to visible light. In this work, the effect of high energy radiation (\begin{document}$\gamma$\end{document}-ray) on the structure and the photocatalytic activity of \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document} nanocrystals was first studied. No morphological change of \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document} nanocrystals was observed by SEM under \begin{document}$\gamma$\end{document}-ray radiation. However, the XRD spectra of the irradiated \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document} nanocrystals showed the characteristic 2\begin{document}$\theta$\end{document} of (113) plane shifts slightly from 28.37\begin{document}$^{\rm{o}}$\end{document} to 28.45\begin{document}$^{\rm{o}}$\end{document} with the increase of the absorbed dose, confirming the change in the crystal structure of \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document}. The XPS results proved the crystal structure change was originated from the generation of oxygen vacancy defects under high-dose radiation. The photocatalytic activity of \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document} on the decomposition of methylene blue (MB) in water under visible light increases gradually with the increase of absorbed dose. Moreover, the improved photocatalytic performance of the irradiated \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document} nanocrystals remained after three cycles of photocatalysis, indicating a good stability of the created oxygen vacancy defects. This work gives a new simple way to improve photocatalytic performance of \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document} through creating oxygen vacancy defects in the crystal structure by \begin{document}$\gamma$\end{document}-ray radiation.     

Experimental and Theoretical Study on p-Chlorofluorobenzene in the S0, S1 and D0 States

The geometric structures and vibration frequencies of \begin{document}$ para $\end{document}-chlorofluorobenzene (\begin{document}$ p $\end{document}-ClFPh) in the first excited state of neutral and ground state of cation were investigated by resonance-enhanced multiphoton ionization and slow electron velocity-map imaging. The infrared spectrum of S\begin{document}$ _0 $\end{document} state and absorption spectrum for S\begin{document}$ _1 $\end{document}\begin{document}$ \leftarrow $\end{document}S\begin{document}$ _0 $\end{document} transition in \begin{document}$ p $\end{document}-ClFPh were also recorded. Based on the one-color resonant two-photon ionization spectrum and two-color resonant two-photon ionization spectrum, we obtained the adiabatic excited-state energy of \begin{document}$ p $\end{document}-ClFPh as 36302\begin{document}$ \pm $\end{document}4 cm\begin{document}$ ^{-1} $\end{document}. In the two-color resonant two-photon ionization slow electron velocity-map imagin spectra, the accurate adiabatic ionization potential of \begin{document}$ p $\end{document}-ClFPh was extrapolated as 72937\begin{document}$ \pm $\end{document}8 cm\begin{document}$ ^{-1} $\end{document} via threshold ionization measurement. In addition, Franck-Condon simulation was performed to help us confidently ascertain the main vibrational modes in the S\begin{document}$ _1 $\end{document} and D\begin{document}$ _0 $\end{document} states. Furthermore, the mixing of vibrational modes between S\begin{document}$ _0 $\end{document}\begin{document}$ \rightarrow $\end{document}S\begin{document}$ _1 $\end{document} and S\begin{document}$ _1 $\end{document}\begin{document}$ \rightarrow $\end{document}D\begin{document}$ _0 $\end{document} has been analyzed.     

Theoretical Studies on Dihedral Angle-Bending Isomers of M2Pt20/-Clusters

The structures and electronic properties of the gaseous M\begin{document}$ _2 $\end{document}Pt\begin{document}$ _2 $\end{document}\begin{document}$ ^{0/-} $\end{document} clusters (M represents the alkaline earth metal) were investigated using the density functional theory (B3LYP and PBE0) and wave function theory (SCS-MP2, CCSD and CCSD (T)). The results indicate that the D\begin{document}$ _{2{h}} $\end{document} isomers with the planar structures are more stable than the C\begin{document}$ _{2v} $\end{document} isomers with smaller dihedral angles and shorter Pt-Pt bond lengths. The mutual competition of M(s, p)-Pt(5d) interaction and Pt-Pt covalent bonding contributes to the different stabilizations of the two kinds of isomers. The M(s, p)-Pt(5d) interaction favors the planar isomers with D\begin{document}$ _{2h} $\end{document} symmetry, while the Pt-Pt covalent bonding leads to the C\begin{document}$ _{2v} $\end{document} isomers with bending structures. Two different crossing points are determined in the potential energy curves of Be\begin{document}$ _2 $\end{document}Pt\begin{document}$ _2 $\end{document} with the singlet and triplet states. But there is just one crossing point in potential energy curves of Ra\begin{document}$ _2 $\end{document}Pt\begin{document}$ _2 $\end{document} and Ca\begin{document}$ _2 $\end{document}Pt\begin{document}$ _2 $\end{document}\begin{document}$ ^- $\end{document} because of flatter potential energy curves of Ra\begin{document}$ _2 $\end{document}Pt\begin{document}$ _2 $\end{document} with the triplet state or Ca\begin{document}$ _2 $\end{document}Pt\begin{document}$ _2 $\end{document}\begin{document}$ ^- $\end{document} with quartet state. The results reveal a unique example of dihedral angle-bending isomers with the smallest number of atoms and may help the understanding of the bonding properties of other potential angle-bending isomers.     

Interaction of CO and 02 with Supported Pt Single-Atoms on TiO2(110)

In view of the high activity of Pt single atoms in the low-temperature oxidation of CO, we investigate the adsorption behavior of Pt single atoms on reduced rutile TiO\begin{document}$ _2 $\end{document}(110) surface and their interaction with CO and O\begin{document}$ _2 $\end{document} molecules using scanning tunneling microscopy and density function theory calculations. Pt single atoms were prepared on the TiO\begin{document}$ _2 $\end{document}(110) surface at 80 K, showing their preferred adsorption sites at the oxygen vacancies. We characterized the adsorption configurations of CO and O\begin{document}$ _2 $\end{document} molecules separately to the TiO\begin{document}$ _2 $\end{document}-supported Pt single atom samples at 80 K. It is found that the Pt single atoms tend to capture one CO to form Pt-CO complexes, with the CO molecule bonding to the fivefold coordinated Ti (Ti\begin{document}$ _{5 \rm{c}} $\end{document}) atom at the next nearest neighbor site. After annealing the sample from 80 K to 100 K, CO molecules may diffuse, forming another type of complexes, Pt-(CO)\begin{document}$ _2 $\end{document}. For O\begin{document}$ _2 $\end{document} adsorption, each Pt single atom may also capture one O\begin{document}$ _2 $\end{document} molecule, forming Pt-O\begin{document}$ _2 $\end{document} complexes with O\begin{document}$ _2 $\end{document} molecule bonding to either the nearest or the next nearest neighboring Ti\begin{document}$ _{5 \rm{c}} $\end{document} sites. Our study provides the single-molecule-level knowledge of the interaction of CO and O\begin{document}$ _2 $\end{document} with Pt single atoms, which represent the important initial states of the reaction between CO and O\begin{document}$ _2 $\end{document}.     

Enhanced Photovoltage for Inverted Perovskite Solar Cells Using Delafossite CuCrO2 Hole Transport Material

Poly(3, 4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) has been widely adopted as hole transport material (HTM) in inverted perovskite solar cells (PSCs), due to high optical transparency, good mechanical flexibility, and high thermal stability; however, its acidity and hygroscopicity inevitably hamper the long-term stability of the PSCs and its energy level does not match well with perovskite materials with a relatively low open-circuit voltage. In this work, p-type delafossite CuCrO\begin{document}$ _2 $\end{document} nanoparticles synthesized through hydrothermal method was employed as an alternative HTM for triple cation perovskite [(FAPbI\begin{document}$ _3 $\end{document})\begin{document}$ _{0.87} $\end{document}(MAPbBr\begin{document}$ _3 $\end{document})\begin{document}$ _{0.13} $\end{document}]\begin{document}$ _{0.92} $\end{document}(CsPbI\begin{document}$ _3 $\end{document})\begin{document}$ _{0.08} $\end{document} (possessing better photovoltaic performance and stability than conventional CH\begin{document}$ _3 $\end{document}NH\begin{document}$ _3 $\end{document}PbI\begin{document}$ _3 $\end{document}) based inverted PSCs. The average open-circuit voltage of PSCs increases from 908 mV of the devices with PEDOT: PSS HTM to 1020 mV of the devices with CuCrO\begin{document}$ _2 $\end{document} HTM. Ultraviolet photoemission spectroscopy demonstrates the energy band alignment between CuCrO\begin{document}$ _2 $\end{document} and perovskite is better than that between PEDOT: PSS and perovskite, the electrochemical impedance spectroscopy indicates CuCrO\begin{document}$ _2 $\end{document}-based PSCs exhibit larger recombination resistance and longer charge carrier lifetime than PEDOT: PSS-based PSCs, which contributes to the high \begin{document}$ V_{\rm{OC}} $\end{document} of CuCrO\begin{document}$ _2 $\end{document} HTM-based PSCs.     

Large-Scale Synthesis of Porous Bi2O3 with Oxygen Vacancies for Efficient Photodegradation of Methylene Blue

Photocatalytic degradation of organic pollutants has become a hot research topic because of its low energy consumption and environmental-friendly characteristics. Bismuth oxide (Bi\begin{document}$ _2 $\end{document}O\begin{document}$ _3 $\end{document}) nanocrystals with a bandgap ranging from 2.0 eV to 2.8 eV have attracted increasing attention due to high activity of photodegradation of organic pollutants by utilizing visible light. Though several methods have been developed to prepare Bi\begin{document}$ _2 $\end{document}O\begin{document}$ _3 $\end{document}-based semiconductor materials over recent years, it is still difficult to prepare highly active Bi\begin{document}$ _2 $\end{document}O\begin{document}$ _3 $\end{document} catalysts in large scale with a simple method. Therefore, developing simple and feasible methods for the preparation of Bi\begin{document}$ _2 $\end{document}O\begin{document}$ _3 $\end{document} nanocrystals in large scale is important for the potential applications in industrial wastewater treatment. In this work, we successfully prepared porous Bi\begin{document}$ _2 $\end{document}O\begin{document}$ _3 $\end{document} in large scale via etching commercial BiSn powders, followed by thermal treatment with air. The acquired porous Bi\begin{document}$ _2 $\end{document}O\begin{document}$ _3 $\end{document} exhibited excellent activity and stability in photocatalytic degradation of methylene blue. Further investigation of the mechanism witnessed that the suitable band structure of porous Bi\begin{document}$ _2 $\end{document}O\begin{document}$ _3 $\end{document} allowed the generation of reactive oxygen species, such as O\begin{document}$ _2 $\end{document}\begin{document}$ ^{-\cdot} $\end{document} and \begin{document}$ \cdot $\end{document}OH, which effectively degraded MB.     

Hydrogen-Assisted C-C Coupling on Reaction of CuC3H-Cluster Anion with CO

A fundamental study on C-C coupling, that is the crucial step in the Fischer-Tropsch synthesis (FTS) process to obtain multi-carbon products, is of great importance to tailor catalysts and then guide a more promising pathway. It has been demonstrated that the coupling of CO with the metal carbide can represent the early stage in the FTS process, while the related mechanism is elusive. Herein, the reactions of the CuC\begin{document}$ _3 $\end{document}H\begin{document}$ ^- $\end{document} and CuC\begin{document}$ _3 $\end{document}\begin{document}$ ^- $\end{document} cluster anions with CO have been studied by using mass spectrometry and theoretical calculations. The experimental results showed that the coupling of CO with the C\begin{document}$ _3 $\end{document}H\begin{document}$ ^- $\end{document} moiety of CuC\begin{document}$ _3 $\end{document}H\begin{document}$ ^- $\end{document} can generate the exclusive ion product COC\begin{document}$ _3 $\end{document}H\begin{document}$ ^- $\end{document}. The reactivity and selectivity of this reaction of CuC\begin{document}$ _3 $\end{document}H\begin{document}$ ^- $\end{document} with CO are greatly higher than that of the reaction of CuC\begin{document}$ _3 $\end{document}\begin{document}$ ^- $\end{document} with CO, and this H-assisted C-C coupling process was rationalized by theoretical calculations.     

Ionization and Dissociation of Benzene and Aniline under Deep Ultraviolet Laser Irradiation

We report a study on photo-ionization of benzene and aniline with incidental subsequent dissociation by the customized reflection time-of-flight mass spectrometer utilizing a deep ultraviolet 177.3 nm laser. Highly efficient ionization of benzene is observed with a weak C\begin{document}$ _4 $\end{document}H\begin{document}$ _3 $\end{document}\begin{document}$ ^+ $\end{document} fragment formed by undergoing disproportional C\begin{document}$ - $\end{document}C bond dissociation. In comparison, a major C\begin{document}$ _5 $\end{document}H\begin{document}$ _6 $\end{document}\begin{document}$ ^{+\cdot} $\end{document} fragment and a minor C\begin{document}$ _6 $\end{document}H\begin{document}$ _6 $\end{document}\begin{document}$ ^{+\cdot} $\end{document} radical are produced in the ionization of aniline pertaining to the removal of CNH\begin{document}$ ^\cdot $\end{document} and NH\begin{document}$ ^\cdot $\end{document} radicals, respectively. First-principles calculation is employed to reveal the photo-dissociation pathways of these two molecules having a structural difference of just an amino group. It is demonstrated that hydrogen atom transfer plays an important role in the cleavage of C\begin{document}$ - $\end{document}C or C\begin{document}$ - $\end{document}N bonds in benzene and aniline ions. This study is helpful to understand the underlying mechanisms of chemical bond fracture of benzene ring and related aromatic molecules.     

Designer Mg-Mg and Zn-Zn Single Bonds Facilitated by Double Aromaticity in the M2B7-(M=Mg,Zn) Clusters

The simple homodinuclear M

\begin{document}$ - $\end{document}

M single bonds for group II and XII elements are difficult to obtain as a result of the fulfilled s

\begin{document}$ ^2 $\end{document}

electronic configurations, consequently, a dicationic prototype is often utilized to design the M

\begin{document}$ ^+ $\end{document}\begin{document}$ - $\end{document}

M

\begin{document}$ ^+ $\end{document}

single bond. Existing studies generally use sterically bulky organic ligands L

\begin{document}$ ^- $\end{document}

to synthesize the compounds in the L

\begin{document}$ ^- $\end{document}\begin{document}$ - $\end{document}

M

\begin{document}$ ^+ $\end{document}\begin{document}$ - $\end{document}

M

\begin{document}$ ^+ $\end{document}\begin{document}$ - $\end{document}

L

\begin{document}$ ^- $\end{document}

manner. However, here we report the design of Mg

\begin{document}$ - $\end{document}

Mg and Zn

\begin{document}$ - $\end{document}

Zn single bonds in two ligandless clusters, Mg

\begin{document}$ _2 $\end{document}

B

\begin{document}$ _7 $\end{document}\begin{document}$ ^- $\end{document}

and Zn

\begin{document}$ _2 $\end{document}

B

\begin{document}$ _7 $\end{document}\begin{document}$ ^- $\end{document}

, using density functional theory methods. The global minima of both of the clusters are in the form of M

\begin{document}$ _2 $\end{document}\begin{document}$ ^{2+} $\end{document}

(B

\begin{document}$ _7 $\end{document}\begin{document}$ ^{3-} $\end{document}

), where the M

\begin{document}$ - $\end{document}

M single bonds are positioned above a quasi-planar hexagonal B

\begin{document}$ _7 $\end{document}

moiety. Chemical bonding analyses further confirm the existence of Mg

\begin{document}$ - $\end{document}

Mg and Zn

\begin{document}$ - $\end{document}

Zn single bonds in these clusters, which are driven by the unusually stable B

\begin{document}$ _7 $\end{document}\begin{document}$ ^{3-} $\end{document}

moiety that is both

\begin{document}$ \sigma $\end{document}

and

\begin{document}$ \pi $\end{document}

aromatic. Vertical detachment energies of Mg

\begin{document}$ _2 $\end{document}

B

\begin{document}$ _7 $\end{document}\begin{document}$ ^- $\end{document}

and Zn

\begin{document}$ _2 $\end{document}

B

\begin{document}$ _7 $\end{document}\begin{document}$ ^- $\end{document}

are calculated to be 2.79 eV and 2.94 eV, respectively, for the future comparisons with experimental data.

     

Are Fulleranes Responsible for the 21 Micron Feature?

Recent detections of C\begin{document}$ _{60} $\end{document}, C\begin{document}$ _{70} $\end{document}, and C\begin{document}$ _{60} $\end{document}\begin{document}$ ^+ $\end{document} in space induced extensive studies of fullerene derivatives in circumstellar environments. As the promising fullerene sources, protoplanetary nebulae (PPNe) shows a number of unidentified bands in their infrared spectra, among which a small sample exhibits an enigmatic feature at \begin{document}$ \sim $\end{document}21 \begin{document}$ \mathtt{μ} $\end{document}m. Hydrogenation converts fullerenes into fulleranes, which breaks the symmetry of fullerene molecules and produces new infrared bands. In this work, we investigate the possibility of fulleranes (C\begin{document}$ _{60} $\end{document}H\begin{document}$ _m $\end{document}) as the carrier of the 21 \begin{document}$ \mathtt{μ} $\end{document}m feature in terms of theoretical vibrational spectra of fulleranes. The evidences favoring and disfavoring the fullerane hypothesis are presented. We made an initial guess for the hydrogen coverage of C\begin{document}$ _{60} $\end{document}H\begin{document}$ _m $\end{document} that may contribute to the 21 \begin{document}$ \mathtt{μ} $\end{document}m feature.     

Mode Specificity Dynamics of Prototypical Multi-Channel H+CH3OH Reaction on Globally Accurate Potential Energy Surface

The H+CH\begin{document}$ _3 $\end{document}OH reaction, which plays an important role in combustion and the interstellar medium, presents a prototypical system with multiple channels. In this work, mode specific dynamics of different product channels is investigated theoretically on a recently developed reliable potential energy surface based on a large number of data points calculated at the level of UCCSD(T)-F12a/AVTZ. It has been demonstrated that vibrational excitations of the O\begin{document}$ - $\end{document}H stretching motion, the torsional motion, the C\begin{document}$ - $\end{document}H stretching vibrations, show different influences on the four product channels, H\begin{document}$ _2 $\end{document}+CH\begin{document}$ _3 $\end{document}O, H\begin{document}$ _2 $\end{document}+CH\begin{document}$ _2 $\end{document}OH, H\begin{document}$ _2 $\end{document}O+CH\begin{document}$ _3 $\end{document}, and H+CH\begin{document}$ _3 $\end{document}OH. This work is helpful for understanding the mode-specific dynamics and controlling the competition for complicated reactions with multiple product channels.     

Location Effect in a Photocatalytic Hybrid System of Metal-Organic Framework Interfaced with Semiconductor Nanoparticles

We report an ultrafast spectroscopy investigation that addresses the subtle location effect in a prototypical semiconductor-MOF hybrid system with TiO\begin{document}$_2$\end{document} nanoparticles being incorporated inside or supported onto Cu\begin{document}$_3$\end{document}(BTC)\begin{document}$_2$\end{document}, denoted as TiO\begin{document}$_2$\end{document}@Cu\begin{document}$_3$\end{document}(BTC)\begin{document}$_2$\end{document} and TiO\begin{document}$_2$\end{document}/Cu\begin{document}$_3$\end{document}(BTC)\begin{document}$_2$\end{document}, respectively. By tracking in real time the interface electron dynamics in the hybrid system, we find that the interface states formed between TiO\begin{document}$_2$\end{document} and Cu\begin{document}$_3$\end{document}(BTC)\begin{document}$_2$\end{document} can act as an effective relay for electron transfer, whose efficiency rests on the relative location of the two components. It is such a subtle location effect that brings on difference in photocatalytic CO\begin{document}$_2$\end{document} reduction using the two semiconductor-MOF hybrids. The mechanistic understanding of the involved interface electron-transfer behavior and effect opens a helpful perspective for rational design of MOF-based hybrid systems for photoelectrochemical applications.     

Unravelling Hydrogen Adsorption Kinetics on Ir(111) Electrode in Acid Solutions by Impedance Spectroscopy

The kinetics for hydrogen (H) adsorption on Ir(111) electrode has been studied in both HClO\begin{document}$ _4 $\end{document} and H\begin{document}$ _2 $\end{document}SO\begin{document}$ _4 $\end{document} solutions by impedance spectroscopy. In HClO\begin{document}$ _4 $\end{document}, the adsorption rate for H adsorption on Ir(111) increases from 1.74\begin{document}$ \times $\end{document}10\begin{document}$ ^{-8} $\end{document} mol\begin{document}$ \cdot $\end{document}cm\begin{document}$ ^{-2} $\end{document}\begin{document}$ \cdot $\end{document}s\begin{document}$ ^{-1} $\end{document} to 3.47\begin{document}$ \times $\end{document}10\begin{document}$ ^{-7} $\end{document} mol\begin{document}$ \cdot $\end{document}cm\begin{document}$ ^{-2} $\end{document}\begin{document}$ \cdot $\end{document}s\begin{document}$ ^{-1} $\end{document} with the decrease of the applied potential from 0.2 V to 0.1 V (vs. RHE), which is ca. one to two orders of magnitude slower than that on Pt(111) under otherwise identical condition. This is explained by the stronger binding of water to Ir(111), which needs a higher barrier to reorient during the under potential deposition of H from hydronium within the hydrogen bonded water network. In H\begin{document}$ _2 $\end{document}SO\begin{document}$ _4 $\end{document}, the adsorption potential is ca. 200 mV negatively shifted, accompanied by a decrease of adsorption rate by up to one order of magnitude, which is explained by the hindrance of the strongly adsorbed sulfate/bisulfate on Ir(111). Our results demonstrate that under electrochemical environment, H adsorption is strongly affected by the accompanying displacement and reorientation of water molecules that initially stay close to the electrode surface.     

Doping Copper Ions in a Metal-Organic Framework (UiO-66-NH2):Location Effect Examined by Ultrafast Spectroscopy

We constructed two types of copper-doped metal-organic framework (MOF), i.e., Cu@UiO-66-NH\begin{document}$ _2 $\end{document} and Cu-UiO-66-NH\begin{document}$ _2 $\end{document}. In the former, Cu\begin{document}$ ^{2+} $\end{document} ions are impregnated in the pore space of the amine-functionalized, Zr-based UiO-66-NH\begin{document}$ _2 $\end{document}; while in the latter, Cu\begin{document}$ ^{2+} $\end{document} ions are incorporated to form a bimetal-center MOF, with Zr\begin{document}$ ^{4+} $\end{document} being partially replaced by Cu\begin{document}$ ^{2+} $\end{document} in the Zr\begin{document}$ - $\end{document}O oxo-clusters. Ultrafast spectroscopy revealed that the photoinduced relaxation kinetics associated with the ligand-to-cluster charge-transfer state is promoted for both Cu-doped MOFs relative to undoped one, but in a sequence of Cu-UiO-66-NH\begin{document}$ _2 $\end{document}\begin{document}$ > $\end{document}Cu@UiO-66-NH\begin{document}$ _2 $\end{document}\begin{document}$ > $\end{document}UiO-66-NH\begin{document}$ _2 $\end{document}. Such a sequence turned to be in line with the trend observed in the visible-light photocatalytic hydrogen evolution activity tests on the three MOFs. These findings highlighted the subtle effect of copper-doping location in this Zr-based MOF system, further suggesting that rational engineering of the specific metal-doping location in alike MOF systems to promote the photoinduced charge separation and hence suppress the detrimental charge recombination therein is beneficial for achieving improved performances in MOF-based photocatalysis.     

Product Vibrational State Distributions of F+CH3OH Reaction on Full-Dimensional Accurate Potential Energy Surface

The hydrogen abstraction reaction of methanol with fluorine atoms can produce HF and CH\begin{document}$ _3 $\end{document}O or CH\begin{document}$ _2 $\end{document}OH radicals, which are important in the environment, combustion, radiation, and interstellar chemistry. In this work, the dynamics of this typical reaction is investigated by the quasi-classical trajectory method based on a recently developed globally accurate full-dimensional potential energy surface. Particularly, the vibrational state distributions of the polyatomic products CH\begin{document}$ _3 $\end{document}O and CH\begin{document}$ _2 $\end{document}OH are determined by using the normal mode analysis method. It is found that CH\begin{document}$ _3 $\end{document}O and CH\begin{document}$ _2 $\end{document}OH are dominantly populated in the ground state when the reactants are at the ground ro-vibrational state. The OH stretching mode, torsional mode, H\begin{document}$ _2 $\end{document}CO out-of-plane bending mode and their combination bands in the CH\begin{document}$ _2 $\end{document}OH product can be effectively excited once the OH stretching mode of the reactant CH\begin{document}$ _3 $\end{document}OH is excited to the first vibrationally excited state. Most of the available energy flows into the HF vibrational energy and the translational energy in both channels, while the radical products, CH\begin{document}$ _3 $\end{document}O or CH\begin{document}$ _2 $\end{document}OH, receive a small amount of energy, consistent with experiment, which is an indication of its spectator nature.     

Sum Frequency Spectroscopy Studies on Cell Membrane Fusion Induced by Divalent Cations

Cell membrane fusion is a fundamental biological process involved in a number of cellular living functions. Regarding this, divalent cations can induce fusion of the lipid bilayers through binding and bridging of divalent cations to the charged lipids, thus leading to the cell membrane fusion. However, the elaborate mechanism of cell membrane fusion induced by divalent cations is still needed to be elucidated. Here, surface/interface sensitive sum frequency generation vibrational spectroscopy (SFG-VS) and dynamic light scattering (DLS) were applied in this research to study the responses of phospholipid monolayer to the exposure of divalent metal ions i.e. Ca\begin{document}$ ^{2+} $\end{document} and Mg\begin{document}$ ^{2+} $\end{document}. According to the particle size distribution results measured by DLS experiments, it was found that Ca\begin{document}$ ^{2+} $\end{document} could induce inter-vesicular fusion while Mg\begin{document}$ ^{2+} $\end{document} could not. An octadecyltrichlorosilane self-assembled monolayer (OTS SAM)-lipid monolayer system was designed to model the cell membrane for the SFG-VS experiment. Ca\begin{document}$ ^{2+} $\end{document} could interact with the lipid PO\begin{document}$ _2 $\end{document}\begin{document}$ ^- $\end{document} head groups more strongly, resulting in cell membrane fusion more easily, in comparison with Mg\begin{document}$ ^{2+} $\end{document}. No specific interaction between the two metal cations and the C=O groups was observed. However, the C=O orientations changed more after Ca\begin{document}$ ^{2+} $\end{document}-PO\begin{document}$ _2 $\end{document}\begin{document}$ ^- $\end{document} binding than Mg\begin{document}$ ^{2+} $\end{document} mediation on lipid monolayer. Meanwhile, Ca\begin{document}$ ^{2+} $\end{document} could induce dehydration of the lipids (which should be related to the strong Ca\begin{document}$ ^{2+} $\end{document}-PO\begin{document}$ _2 $\end{document}\begin{document}$ ^- $\end{document} interaction), leading to the reduced hindrance for cell membrane fusion.