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Recently, gold nanoparticles (Au NPs) have been used to study the treatment of malignant tumors due to their higher biocompatibility and lesser toxicity. In addition, they can be excited through a specific wavelength to produce oscillating plasmonic photothermal therapy (PPTT) on the basis of the localized surface plasma resonance (LSPR) effect. Au NPs can be heated to kill cancer cells in specific parts of the body in a noninvasive manner. In this study, branched gold nanoparticles (BAu NPs) were prepared by mixing HAuCl4 in a 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer solution in a molar ratio of 1:2000. The UV&ndash, vis absorption peak was detected in the range of 700&ndash, 1000 nm. Subsequently, BAu NPs were chemically linked to a thiol-modified mannoside molecule via a stable sulfur&ndash, Au covalent bond (Man@BAu NPs). Due to the presence of abundant mannose receptors on human-breast-cancer cells, MDA-MB-231, Man@BAu NPs were found to be abundant inside cancer cells. After irradiating the Man@BAu NP-laden MDA-MB231 switch with a near-infrared (NIR) laser at 808 nm wavelength, the photothermal-conversion effect raised the surface temperature of Man@BAu NPs, thus inducing cell death. Our experiment results demonstrated the advantages of applying Man@BAu NPs in inducing cell death in MDA-MB-231.

Light-driven sodium ion pump rhodopsin (NaR) is a new functional class of microbial rhodopsin. A previous flash photolysis study of Krokinobacter eikastus rhodopsin 2 (KR2) revealed the presence of three kinetically distinct intermediates: K, L/M, and O. Previous low-temperature Fourier-transform infrared (FTIR) spectroscopy of KR2 showed that photoisomerization from the all-trans to the 13-cis form is the primary event of the Na+ pumping photocycle, but structural information on the subsequent intermediates is limited. Here, we applied step-scan time-resolved FTIR spectroscopy to KR2 and Nonlabens dokdonensis rhodopsin 2 (NdR2). Both low-temperature static and time-resolved FTIR spectra resolved a K-like intermediate, and the corresponding spectra showed few differences. Strong hydrogen-out-of-plane (HOOP) vibrations, which appeared in the K intermediate, are common among other rhodopsins. It is, however, unique for NaR that such HOOP bands are persistent in late intermediates, such as L and O intermediates. This observation strongly suggests similar chromophore structures for the K, L, and O intermediates. In fact, an isotope-labeled study that used 12,14-D2 retinal revealed that the chromophore configuration of the O intermediate in NaR is 13-cis. In contrast to the vibrations of the chromophore, those of the protein differ among intermediates, and this is related to the sodium-pumping function. The molecular mechanism of the light-driven sodium pump is discussed on the basis of the present time-resolved FTIR results.

The reaction of iron(ii) and hydrogen peroxide, namely the Fenton reaction, is well-known for its strong oxidizing capability. While the Fenton reactions are ubiquitous and have wide applications in many areas, the detailed mechanism, especially the nature of the reactive intermediates responsible for oxidation, is not completely clear. In this work, the performances of various density functional theory (DFT) methods on the relative energies of key Fenton intermediates are evaluated. The DFT method selected from the benchmark study is then exploited to investigate the aqueous Fenton reactions in different pH conditions. The results show that at pH > 2.2, the major Fenton oxidants are high-valent oxoiron(iv) aquo complexes. However, depending on the pH conditions, these complexes can exist in three protonation states that display quite different oxidation reactivities. The oxidizing power of FeIV[double bond, length as m-dash]O is found to be principally determined by the total charge of the ligands and is less influenced by the axial ligand effect. Moreover, the calculations reveal that the presence of the hydronium ion can stabilize the intermediate of the hydroxyl radical and further inhibit oxoiron(iv) formation via proton transfer. The contribution of hydroxyl radicals could compete with the oxoiron(iv) species at pH below 2.2. In addition, high-level ab initio calculations question the existence of the iron(iv)-dihydroxo intermediate suggested in the literature. The implications of the computational results for the Fenton oxidation process, cytochrome P450, and catalyst design are discussed.

Allene and propyne as well as their cationic forms play important roles in combustion and interstellar chemistry and serve as a model system for molecular spectroscopic studies. Both cations show Jahn–Teller (J–T) distortions in their ground states. These J–T distortions make the theoretical and experimental studies of their electronic structures difficult. We produced allene cations upon electron bombardment during matrix deposition of Ar containing a small proportion of allene. The intensities of the absorption features of the allene cation decreased after irradiation with UV light, whereas new bands attributed to propyne cations increased. The observed line wavenumbers, relative intensities, and deuterium-substituted isotopic ratios of the isomers of C3H4+ agree satisfactorily with those predicted by density functional theory at the B3PW91/aug-cc-pVTZ level of theory. This method produced the hydrocarbon cations of interest with few other fragments that enabled the clear identification of the IR spectr...

Two μ₂-tetrazolyl bridged metal complexes, ([CdI(PTZ)(H₂O)]·H₂O)ₙ1 and ([Cu(PTZ)₂]·H₂O)ₙ2 (HPTZ=5-(pyrazinyl) tetrazolate), were hydrothermally synthesized and fully characterized by X-ray crystallography, elemental analyses and spectrum techniques. In 1, cadmium ions are bridged by tridentate μ₂-κ²N2,N5:κ¹N1 chelating PTZ⁻ ligand and halide linkers into an infinite 1D chain, while in 2 copper ions are connected by tridentate μ₂-κ²N7,N12:κ¹N8 and bidentate μ₂-κ¹N1:κ¹N2 chelating-bridging PTZ⁻ ligands to form a 1D castellated chain structure. Compound 1 displays phosphorescence with a lifetime of ~7.74 ms in the visible region, and the origin of the luminescent emission is primary assigned to the combination of ligand-centered emission, metal-to-ligand charge transfer and ligand-to-ligand charge transfer, which has been probed by the density of states (DOS) calculations. Magnetic measurement reveals that compound 2 displays an anti-ferromagnetic ordering. - Graphical abstract: Two new complexes based on 5-(pyrazinyl) tertrazolate, namely ([CdI(PTZ)(H2O)]·H2O)n and ([Cu(PTZ)2]·H2O)n have been synthesized and characterized. Compound 1 exhibits interesting green luminescence. Compound 2 displays an anti-ferromagnetic ordering. Highlights: • We report two novel 1D μ₂-tetrazolyl bridged Cd(II) and Cu(II) compounds. • The cadmium(II) compound exhibits a green luminescence. • Theoretical calculations were conducted to elucidate the green luminescence. • The Cu(II) compound exhibits an anti-ferromagnetic ordering.

A novel tetranuclear cadmium complex {Cd2[(CH3)2PPDA]2(CH3OH)Cl4}2 (1) [(CH3)2PPDA = dimethyl esterification of H2PPDA], was prepared from CdCl2·2.5H2O with (2,3-f)-pyrazino(1,10)phenanthroline-2,3-dicarboxylic acid (H2PPDA) by solvothermal reaction in methanol, and characterized by single-crystal X-ray diffraction analysis, optical diffuse reflectance and photoluminescence. In 1, cadmium ions are bridged by Cl− ions into a tetranuclear oligomeric chain further connected into a 3D supramolecular network by intermolecular C H⋯Cl, O H⋯Cl, and C H⋯O hydrogen bonds. Compound 1 displays fluorescence with a lifetime value of ~ 5.88 ns in the visible region under visible-light excitation, and the origin of the luminescent emission is primary assigned to the combination of intraligand π–π* transition of (CH3)2PPDA ligand and ligand to ligand charge transfer from Cl− to (CH3)2PPDA which is probed by the density of state (DOS) calculations.

The absorption spectrum of ethyne, C2H2, in solid Ar was measured in the wavelength region 107-220 nm with light from a synchrotron. Based on that absorption, irradiation of samples of ethyne dispersed in neon with vacuum-ultraviolet (VUV) radiation yielded various products that were identified through their infrared absorption spectra including C n (n = 3-12), C2H, C2H3, C4H, C4H2, C8H–, and C8H2. The efficiency of photolysis of ethyne and the nature of photoproducts depend on the selected wavelength of VUV light. Information about the photodissociation of C2H2 with various photon energies and the formation and identification of large carbon clusters and hydrides at low temperature might be useful in photochemical models to simulate the composition of the atmosphere of Titan and as a source of aerosols.

Photolysis of methane dispersed (1/1000) in solid Ne at 3 K with vacuum-ultraviolet light from a synchrotron produced infrared absorption lines of several products, including new lines at 3319.3 and 1955.5 cm–1. Based on experiments with isotopic labeling and results of quantum-chemical calculations, these lines are assigned to the C-H stretching and C=C stretching modes, respectively, of interstellar molecule linear C5H radicals.

Chemical reactions of C2H4 dispersed in solid nitrogen at 10 K that occur upon irradiation with Lyα light at a wavelength of 121.6 nm and 500 eV electrons were investigated by measuring the infrared absorption spectra. Photolysis of the matrix samples with 121.6 nm light yielded products, including C2H2, CN, and isomers of C2N2, as well as a pair of HCN and HNC. In contrast, electron bombardment of similar matrix samples mainly resulted in the generation of N3, C2H2, C2H3, C3H2, and C3N−. Mechanisms of the reactions that occur during the photolysis and electron-radiation of the matrix samples are discussed. The results of the study provide insights into the formation of HNC and HCN, as well as nitriles, in N2-rich ice samples containing a small proportion of C2H4.

Cisplatin, Pt(NH3)2Cl2, is a leading chemotherapeutic agent that has been widely used for various cancers. Recent experiments show that combining cisplatin and electron sources can dramatically enhance DNA damage and the cell-killing rate and, therefore, is a promising way to overcome the side effects and the resistance of cisplatin. However, the molecular mechanisms underlying this phenomenon are not clear yet. By using density functional theory calculations, we confirm that cisplatin can efficiently capture the prehydrated electrons and then undergo dissociation. The first electron attachment triggers a spontaneous departure of the chloride ion, forming a T-shaped [Pt(NH3)2Cl]˙ neutral radical, whereas the second electron attachment leads to a spontaneous departure of ammine, forming a linear [Pt(NH3)Cl](-) anion. We further recognize that the one-electron reduced product [Pt(NH3)2Cl]˙ is extremely harmful to DNA. It can abstract hydrogen atoms from the C-H bonds of the ribose moiety and the methyl group of thymine, which in turn leads to DNA strand breaks and cross-link lesions. The activation energies of these hydrogen abstraction reactions are relatively small compared to the hydrolysis of cisplatin, a prerequisite step in the normal mechanism of action of cisplatin. These results rationalize the improved cytotoxicity of cisplatin by supplying electrons. Although the biological effects of the two-electron reduced product [Pt(NH3)Cl](-) are not clear at this stage, our calculations indicate that it might be protonated by the surrounding water.