Utilizing a customized multiple-ion laminar flow tube reactor in tandem with a triple quadrupole mass spectrometer, we report a study of the gas-phase reactivity of Ag n + clusters with acetylene. Well-resolved Ag n + clusters (n = 1–20) are produced by a self-designed magnetron sputtering source (MagS); however, on their reactions with acetylene under sufficient collisional conditions, only Ag7 +[C2H2] is produced with a reasonable intensity. DFT calculations reveal that Ag n + clusters do not form strong Ag–C bonds with C2H2 and Ag7 +[C2H2] bears larger binding energy than the other Ag n +[C2H2] although within similar cluster−π interactions. Besides gas-phase reaction rate estimation, the relatively large noncovalent cluster−π interaction in Ag7 +[C2H2] is fully demonstrated via topological analysis and natural bonding orbital analysis. Also, we illustrate both thermodynamically and kinetically favored channels in producing the Ag7 +[C2H2]. This study helps in understanding metal-involved noncovalent bonds and how such weak interactions are able to tune the material function and biological activity.

Metal clusters including those supported on graphene-based materials have attracted extensive research interest in the past decade allowing dissection of the interfaces, stability, electronic properties, and catalytic activities at an atomically precise scale. Here, we have synthesized glutathione-protected Ag 6 clusters via a facile green reaction route, transferred onto graphene oxide (GO) and exploit as catalyst for cyclohexane oxidation under ambient conditions. High selectivity and high yields to produce cyclohexanone are attained with tert-butyl hydroperoxide (TBHP) as the oxidant in the oxygen-flowing atmosphere. Based on density functional theory calculations, it is demonstrated that both TBHP and oxygen interact with the GO-supported Ag 6 clusters, giving rise to the peroxide structure and hence facilitating the catalytic oxidation of cyclohexane. It is interestingly found that the hydrogen-added hydroperoxyl (−OOH) brings forth largely decreased activation barrier for the O−O bond dissociation. The O−O dissociated intermediate then reacts with cyclohexane to form cyclohexanol, followed by successive oxidative dehydrogenation to produce cyclohexanone. This finding verifies the enhanced catalysis of TBHP and O 2 for the conversion of cyclohexane to cyclohexanone and helps to develop heterogeneous catalysts of metal clusters for efficient C−H activation.

The application of low-fragmentation mass spectrometry to identify chemicals has been recognized to be of particular importance in chemistry, biomedicine, and materials science. Utilizing a customized all-solid-state picosecond-pulsed deep-ultraviolet (DUV) laser, here we present new advances into photoionization mass spectrometry. The DUV laser ionization mass spectrometry (DUV-LIMS) results in very clean spectra pertaining to minimized structure relaxation and fragmentation under the ultrafast ionization process. Typical DUV-LIMS applications are illustrated not only for small organic molecules but also for long-chain unsaturated hydrocarbons and clusters of benzene. The unique advantages of DUV-LIMS enable us to detect and analyze confusing organic compound mixtures, indicating promising applications. DUV-LIMS is also found to be applicable in the identification of phenylenediamine isomers. An in-depth analysis of reaction dynamics is provided showing how hydrogen-atom-transfer (HAT) initiates the distinguishable photodissociation of phenylenediamines under near-resonant excitation. In particular, ortho-phenylenediamine (OPD) finds a remarkable dehydrogenation product with comparable intensity to the molecular ion peak, which is associated with the quantum tunnelling tautomers, providing new subjects for studying intramolecular noncovalent interactions.