We report facile synthesis of the Au(SG) nanoclusters, where SG stands for glutathione, found to be promising as a new class of radiosensitizers for cancer radiotherapy. The homoleptic catenane structure with two AuSG interconnected rings, among different isomer structures, gives the best agreement between theoretical and experimental optical spectra and XRD patterns. This catenane structure exhibits a centrosymmetry-broken structure, resulting in enhanced second harmonic response and new characteristic circular dichroism signals in the spectral region of 250-400 nm. This is the first determination of the nonlinear optical properties of a ligated cluster with an equal Au-to-ligand ratio, thus without a metallic core and therefore zero confined electrons. Insight into the nonlinear and chiroptical efficiencies arising from interplay between structural and electronic properties is provided by the TD-DFT approach.

Incorporating anisotropic surface charges on atomically precise gold nanoclusters led to a intense shortwave infrared photoluminescence exceeding 1100 nm with QY up to 6.1%.

Ion mobility (IM) is now a well-established and fast analytical technique. The IM hardware is constantly being improved, especially in terms of the resolving power. The Drift Tube (DTIMS), the Traveling Wave (TWIMS), and the Trapped Ion Mobility Spectrometry (TIMS) coupled to mass spectrometry are used to determine the Collision Cross-Sections (CCS) of ions. In analytical chemistry, the CCS is approached as a descriptor for ion identification and it is also used in physical chemistry for 3D structure elucidation with computational chemistry support. The CCS is a physical descriptor extracted from the reduced mobility (K) measurements obtainable only from the DTIMS. TWIMS and TIMS routinely require a calibration procedure to convert measured physical quantities (drift time for TWIMS and elution voltage for TIMS) into CCS values. This calibration is a critical step to allow interinstrument comparisons. The previous calibrating substances lead to large prediction bands and introduced rather large uncertainties during the CCS determination. In this paper, we introduce a new IM calibrant (CCS and K) using singly charged sodium adducts of poly(ethylene oxide) monomethyl ether (CHO-PEO-H) for positive ionization in both helium and nitrogen as drift gas. These singly charged calibrating ions make it possible to determine the CCS/K of ions having higher charge states. The fitted calibration plots exhibit larger coverage with less data scattering and significantly improved prediction bands and uncertainties. The reasons for the improved CCS/K accuracy, advantages, and limitations of the calibration procedures are also discussed. A generalized IM calibration strategy is suggested.

The shape of the spectral features in arrival time distributions (ATDs) recorded by ion mobility spectrometry (IMS) can often be interpreted in terms of the coexistence of different isomeric species. Interconversion between such species is also acknowledged to influence the shape of the ATD, even if no general quantitative description of this effect is available. We present an analytical model that allows simulating ATDs resulting from interconverting species. This model is used to reproduce experimental data obtained on a bistable system and to interpret discrepancies between measurements on different types of instruments. We show that the proposed model can be further exploited to extract kinetic and thermodynamic data from tandem-IMS measurements.

We report a simple size focusing, two-step “bottom-up” protocol to prepare water-soluble Au 25 (MBA) 18 nanoclusters, using the three isomers of mercaptobenzoic acids ( p / m / o -MBA) as capping ligands and Me 3 NBH 3 as a mild reducing agent. The relative stability of the gas-phase multiply deprotonated Au 25 (MBA) 18 ions was investigated by collision-induced dissociation. This permitted us to evaluate the possible isomeric effect on the Au–S interfacial bond stress. We also investigated their optical properties. The absorption spectra of Au 25 (MBA) 18 isomers were very similar and showed bands at 690, 470, and 430 nm. For all Au 25 (MBA) 18 isomeric clusters, no measurable one-photon excited fluorescence under UV–vis light was found, in neither solid- nor solution-state. The two-photon excited emission spectra and first hyperpolarizabilities of the clusters were also determined. The results are discussed in terms of the possible isomeric effect on excitations within the metal core and the possibility of charge transfer excitations from the ligands to the metal nanocluster.

We report a combined experimental and theoretical study of the two-photon absorption and excited emission properties of monodisperse ligand stabilized Ag, Ag and Ag nanoclusters in aqueous solutions. The nanoclusters were synthesized using a cyclic reduction under oxidative conditions and separated by vertical gel electrophoresis. The two-photon absorption cross-sections of these protected noble metal nanoclusters measured within the biologically attractive 750-900 nm window are several orders of magnitude larger than that reported for commercially available standard organic dyes. The two-photon excited fluorescence spectra are also presented for excitation wavelengths within the same excitation spectral window. They exhibit size-tunability. Because the fundamental photophysical mechanisms underlying these multiphoton processes in ligand protected clusters with only a few metal atoms are not fully understood yet, a theoretical model is proposed to identify the key driving elements. Elements that regulate the dipole moments and the nonlinear optical properties are the nanocluster size, its structure and the charge distribution on both the metal core and the bound ligands. We coined this new class of NLO materials as "Ligand-Core" NLO-phores.

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The crucial role of solubilization and crystallization steps in the vibrational and optical properties of {Ta6Bri12} cluster core containing systems.