New Three-Dimensional Supramolecular Framework: Crystal Structure and Photocatalytic Property.

In this work, benzimidazole (Hbim) and Cu(II) ions ligands were chosen as building blocks to produce a novel Cu(II) compound (CP) based on {Cu4O}cluster, namely, [Cu4OCl6(Hbim)4]n·n(H2O)·2n(EtOH) (1). The investigation of SCXRD reveals that the CP 1 is a separated 0D structure based on tetrahedral {Cu4O} clusters. Furthermore, this supramolecular frame displayed superior photocatalytic effect on the photodegradation of MB under UV light irradiation.

Application Values of Two Cu(II) Schiff Base Coordination Complexes on Blue Fluorescent Materials.

Two Schiff base binuclear Cu(II) compounds, [Cu2(L)2·(H2O)2]·2DMF (1) together with its coordination polymer (CP) [Cu2(L)2·(4,4'-bpy)2]n (2) (H2L is 4-hydroxy-3-((2-hydroxy-5-mercaptobenzylidene)amino)-2H-chromen-2-one and 4,4'-bpy is 4,4'-bipyridine), were generated under an identical experimental environment in the absence and existence of auxiliary ligand 4,4'-bpy. Fluorescence spectroscopy testing shows that the ligand-based blue fluorescence emission offers potential for application as a blue photoluminescent material.

Synthesis and Fluorescent Characteristics Study of Two Novel Co(II) Complexes.

In this work, two novel mixed-ligand CPs that has a compositions of [Co2(µ-Hdppa)2(phen)2(H2O)2] (1) and {[Co(µ-Hdppa)(µ-4,4'-bipy)(H2O)]·H2O}n (2) is achieved through reaction of cobalt salts with the 5-(3,4-Dicarboxylphenyl)picolinic acid (H3dppa) with various N-donor co-ligands (1,10-phenanthroline (phen) for 1 and 4,4'-bipyridine (4,4'-bipy) for 2). The structures and characteristics of these two complexes were fully examined via IR, TGA, and SXRD. Furthermore, their superior blue fluorescence properties compared to the original ligands were confirmed through fluorescence spectroscopy. These two complexes prepared in this study have enriched the choices for blue fluorescent materials.

Potential Application Values of Two Multicoloured Coordination Compounds as Multicolor Luminescent Materials.

Two Co(II)-based coordination compounds, namely {[Co(apc)2]·H2O}n (1) and [Co(apc)2(H2O)2] (2), have been successfully prepared via reaction of a multifunctional ligand 2-aminopyrimidine-5-carboxylic acid (Hapc) with Co(NO3)2·6H2O based on different reaction environments. Both compounds were studied via elemental analysis (EA), single crystal X-ray diffraction analysis (SC-XRD), thermogravimetric analysis (TG), powder X-ray diffraction (PXRD) and infrared spectroscopy (IR). Fluorescence spectroscopy was employed to analyze the fluorescence properties of the ligand and the two compounds. The results revealed that the two compounds exhibited green and blue fluorescence, surpassing the original ligand in terms of properties. Based on the distinct fluorescence colors of the two compounds, there is potential to create multicolored fluorescent materials by adjusting their material ratios. This prospect could further extend their applications in the field of fluorescent materials.

Bonding character, electronic properties, and electronic transitions of perfluorocubane as a small electron acceptor.

Perfluorocubane is a fluorinated analogue of a polyhedral hydrocarbon observed recently in experiment (M. Sugiyama, M. Akiyama, Y. Yonezawa, K. Komaguchi, M. Higashi, K. Nozaki and T. Okazoe, Electron in a cube: Synthesis and characterization of perfluorocubane as an electron acceptor, Science, 2022, 377, 756-759). Inspired by its unique structure and electronic properties, we systematically explored its chemical stabilities, bonding character, electronic properties, and electronic transitions using density functional theory calculations. Analysis of the binding energies and Mayer bond orders reveals that the C8F8 molecule has high chemical stability with a special electronic structure, and the addition of an extra electron to the neutral molecule may generate a radical anion with a hosted electron inside the cubane frame. The induced ring currents under an external magnetic field reveal that perfluorocubane exhibits an overall small diamagnetic current supported by anisotropy of the current-induced density (ACID) and gauge-including magnetically induced currents (GIMIC). AdNDP analysis indicates that the localized two-center two-electron (2c-2e) σ-bonds are responsible for structural stabilization of the molecule. Further study into the electronic excitations shows that the main electronic transitions of perfluorocubane come from the surface of the cubic frame to its inner structure. Consequently, perfluorocubane can be recognized as a small electron acceptor material due to its special electron-carrying capacity, which will promote further applications of novel conducting and semiconducting materials.

Release of the Water Molecule Encapsulated Inside an Open-Cage Fullerene through Hydrogen Bonding Mediated by Hydrogen Fluoride.

A reversible wetting/dewetting procedure is reported for an open-cage fullerene with an 18-membered orifice. In a homogeneous mixture of H2O/EtOH/CHCl3, water was encapsulated into the cavity of the open-cage compound quantitatively at 80 °C. Addition of aqueous hydrogen fluoride into the water-encapsulated complex removed the encapsulated water completely at room temperature. H-bonding between the trapped water and fluoride is shown to play a key role for the water release process.

Decomposition reaction rate of BCl3-C3H6(propene)-H2 in the gas phase.

The decomposition reaction rate in the BCl(3)-C(3)H(6)-H(2) gas phase reaction system in preparing boron carbides was investigated based on the most favorable reaction pathways proposed by Jiang et al. [Theor. Chem. Accs. 2010, 127, 519] and Yang et al. [J. Theor. Comput. Chem. 2012, 11, 53]. The rate constants of all the elementary reactions were evaluated with the variational transition state theory. The vibrational frequencies for the stationary points as well as the selected points along the minimum energy paths (MEPs) were calculated with density functional theory at the B3PW91/6-311G(d,p) level and the energies were refined with the accurate model chemistry method G3(MP2). For the elementary reaction associated with a transition state, the MEP was obtained with the intrinsic reaction coordinates, while for the elementary reaction without transition state, the relaxed potential energy surface scan was employed to obtain the MEP. The rate constants were calculated for temperatures within 200-2000 K and fitted into three-parameter Arrhenius expressions. The reaction rates were investigated by using the COMSOL software to solve numerically the coupled differential rate equations. The results show that the reactions are, consistent with the experiments, appropriate at 1100-1500 K with the reaction time of 30 s for 1100 K, 1.5 s for 1200 K, 0.12 s for 1300 K, 0.011 s for 1400 K, or 0.001 s for 1500 K, for propene being almost completely consumed. The completely dissociated species, boron carbides C(3)B, C(2)B, and CB, have very low concentrations, and C(3)B is the main product at higher temperatures, while C(2)B is the main product at lower temperatures. For the reaction time 1 s, all these concentrations approach into a nearly constant. The maximum value (in mol/m(3)) is for the highest temperature 1500 K with the orders of -13, -17, and -23 for C(3)B, C(2)B, and CB, respectively. It was also found that the logarithm of the overall reaction rate and reciprocal temperature have an excellent linear relationship within 700-2000 K with a correlation coefficient of 0.99996. This corresponds to an apparent activation energy 337.0 kJ/mol, which is comparable with the energy barrier 362.6 kJ/mol of the rate control reaction at 0 K but is higher than either of the experiments 208.7 kJ/mol or the Gibbs free energy barrier 226.2 kJ/mol at 1200 K.

Theoretical Investigation of 6-Mercaptopurine Isomers' Adsorption on the Au(001) Surface: Revealing the Fate of Different Isomers.

Density functional theory (DFT) calculations were performed for the adsorption of different isomers of 6-mercaptopurine on the Au(001) surface. All of the configurations of four thione and two thiol isomers were considered. The results show that the thione isomers adsorbed more strongly on the Au(001) surface compared with the thiol ones. In all of the configurations, the calculated binding energy of ma-8 is the largest, in which the S atom of 6-mercaptopurine binds strongly with one Au atom on the monodentate sites and 6-mercaptopurine retains a flat geometry, predominantly with an approximately 30° orientation between the C-S bond and the Au-Au bond of the catalyst. Additionally, the 6-mercaptopurines in ma-2, mb-5, and mc-3 also bind more strongly onto the surface, which show relatively higher stability on the surfaces, indicating a high preference for adsorption. Charge density differences and TDOS analyses for the four configurations also show that the electronic charges are accumulated between Au and S atoms in the Au-S bonds, indicating occurrence of adsorption and chemical-bond formation.

A new insight of structures, bonding and electronic properties for 6-mercaptopurine and Ag8 clusters configurations: a theoretical perspective.

BACKGROUND: Many reports have also shown that the silver nanoparticles can effectively increase the anticancer drug activity and intensely enhance the drug curative effect. The adsorption of 6MP on nanomaterials has received a lot of attentions because of the drug coordination to its chemotherapeutic activity. The geometrical structures, chemical bonds, molecular orbital properties as well as density of states for the configurations were analyzed to deeply understand the interactions between the 6MP and Ag8 clusters for high effect anticancer drug production. RESULTS: In this work, the density functional theory B3LYP has been used to investigate the structures and properties of the configurations between 6-mercaptopurine (6MP) and Ag8 clusters using 6-311++G** level as well as an effective pseudo potential LANL2DZ. The geometries of ten configurations were optimized with full freedom. The geometrical structures, chemical bonds, molecular orbital properties as well as density of states for partial configurations were analyzed based on the density functional calculations. Polarizable continuum solvent model (PCM) in self-consistent reaction field (SCRF) were used for the aqueous calculations. The influences of temperature and pressure on the stability of the predominant configurations in the gas phase were further considered using standard statistical thermodynamic methods from 50 to 500 K and at 1 bar or 100 bar. CONCLUSION: The result shows that there are ten stable configurations in the gas phase and there is a strong chemical bond between a Ag and S atom in the most stable configuration. The analysis of density of states also shows that the Ag-S chemical bond in the most stable configuration has been formed. Moreover, the results show that the temperature and the pressure will significantly influence the stability of the configurations in the gas phase. Additionally, when the solvent effect was considered, we found that there are only seven stable configurations and the solvent have different effect on various configurations.

First-Principles Study of Structural, Electronic and Magnetic Properties of Metal-Centered Tetrahexahedral V15⁺ Cluster.

The V-centered bicapped hexagonal antiprism structure (A), as the most stable geometry of the cationic V15⁺ cluster, is determined by using infrared multiple photo dissociation (IR-MPD) in combination with density functional theory computations. It is found that the A structure can be stabilized by 18 delocalized 3c-2e σ-bonds on outer V3 triangles of the bicapped hexagonal antiprism surface and 12 delocalized 4c-2e σ-bonds on inner trigonal pyramidal V4 moiety, and the features are related to the strong p-d hybridization of the cluster. The total magnetic moments on the cluster are predicted to be 2.0 µB, which come mainly from the central vanadium atom.

Double Biocatalysis Signal Amplification Glucose Biosensor Based on Porous Graphene.

Controllable preparation of nanopores to promote the performance of electrochemical biosensing interfaces has become one of the researching frontiers in biosensing. A double biocatalysis signal amplification of glucose biosensor for the study of electrochemical behaviors of glucose oxidase (GOx) was proposed by using horseradish peroxidase biosynthesized porous graphene (PGR) as the platform for the biocatalytic deposition of gold nanoparticles (AuNPs). The biosensor showed a linear range from 0.25 to 27.5 µM with a detection limit of 0.05 µM (S/N = 3) towards glucose. Furthermore, the proposed AuNPs/GOx-PGR modified glassy carbon electrode (AuNPs/GOx-PGR/GCE) achieved direct electron transfer of GOx.

Effect of Alkali Metal Atoms Doping on Structural and Nonlinear Optical Properties of the Gold-Germanium Bimetallic Clusters.

A new series of alkali-based complexes, AM@GenAu (AM = Li, Na, and K), have been theoretically designed and investigated by means of the density functional theory calculations. The geometric structures and electronic properties of the species are systematically analyzed. The adsorption of alkali metals maintains the structural framework of the gold-germanium bimetallic clusters, and the alkali metals prefer energetically to be attached on clusters' surfaces or edges. The high chemical stability of Li@Ge12Au is revealed by the spherical aromaticity, the hybridization between the Ge atoms and Au-4d states, and delocalized multi-center bonds, as well as large binding energies. The static first hyperpolarizability (ßtot) is related to the cluster size and geometric structure, and the AM@GenAu (AM = Na and K) clusters exhibit the much larger ßtot values up to 13050 a.u., which are considerable to establish their strong nonlinear optical (NLO) behaviors. We hope that this study will promote further application of alkali metals-adsorbed germanium-based semiconductor materials, serving for the design of remarkable and tunable NLO materials.

Exploring the chemical bonding, infrared and UV-vis absorption spectra of OH radicals adsorption on the smallest fullerene.

In the present work, the density-functional theory calculations were performed on C20 hydroxylated fullerene. B3LYP functionals with 6-31G(d,p) basis set were utilized to gain insight into the bonding characters and intramolecular interactions of hydroxyl groups adsorbed on the cage. Interestingly, we observed that the C20 cage has the bonding patterns with spherical orbitals configuration [1S(2)1P(6)1D(10)1F(2)], and the adsorbed hydroxyl groups significantly affect the chemical bonding of the cage surface. Analysis of vertical electron affinities and vertical ionization potentials indicates that the polyhydroxylated derivative with eight hydroxyl groups is more stable than others. The intramolecular interaction of these derivatives considered here reveals that the more the hydroxyl groups in derivatives, the stronger the interaction in stabilizing structures. On the basis of theoretical studies, the hydroxyl groups largely enhance the infrared intensities, especially for the polyhydroxylated derivatives.

A theoretical investigation on the proton transfer tautomerization mechanisms of 2-thioxanthine within microsolvent and long range solvent.

A relative complete study on the mechanisms of the proton transfer reactions of 2-thioxanthine was carried out with density functional theory. The models were designed with monohydrated and dihydrated microsolvent catalyses either with or without the presence of water solvent considered with the polarized continuum model (PCM). A total number of 114 complexes and 67 transition states were found with the B3LYP/6-311+G** calculations. The energies were refined with both B3LYP/aug-cc-pVTZ and PCM-B3LYP/aug-cc-pVTZ methods. The activation energies were reported with respect to the Gibbs free energies obtained in conjunction with the standard statistical thermodynamics. Possible reaction pathways were confirmed with the intrinsic reaction coordinates. Pathways via C8 atom on the imidazole ring, via the bridged C4 and C5 atoms between pyrimidine and imidazole rings and via N, O and S atom on the pyrimidine ring were examined. The results show that the most feasible pathway is the proton transfers within the long range solvent surrounding via the N, O and S atoms in the pyrimidine ring with di-hydrated catalysis: N(7)H + 2H2O → IM89 → IM90 → P13 + 2H2O → IM91 → IM92 → P6 + 2H2O → IM71 → IM72 → P7 + 2H2O → IM107 → IM108 → P18 + 2H2O → IM111 → IM112 → P19 + 2H2O → IM113 → IM114 → P17 + 2H2O → IM105 → IM106 → N(9)H + 2H2O that has the highest energy barrier of 44.0 kJ mol(-1) in the transition of IM89 to IM90 via TS54. The small energy barrier is in good agreement with the experimental observation that 2-TX tautomerizes at room temperature in water. In the aqueous phase, the most stable intermediate is found to be IM21 [N(7)H + 2H2O] and the possible co-existing species are the monohydrated IM1, IM9, IM39 and IM46, and the di-hydrated IM5, IM8, IM13, IM16, IM81, IM89, IM90, IM91 and IM106 complexes that have a relative concentration larger than 10(-6) (1 ppm) with respect to IM21.