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Some of the authors of the present research group have previously reported mass spectrometric detection of [PdAu9(PPh3)8(CN)]2+ (PdAu9CN) by atmospheric pressure plasma (APP) irradiation of [MAu8(PPh3)8]2+ (PdAu8) in methanol and proposed based on density functional theory (DFT) calculations that PdAu9CN is constructed by inserting a CNAu or NCAu unit into the Au–PPh3 bond of PdAu8 [Emori et al., J. Chem. Phys. 155, 124312 (2021)]. In this follow-up study, we revisited the structure of PdAu9CN by high-resolution ion mobility spectrometry on an isolated sample of PdAu9CN with the help of dispersion-corrected DFT calculation. In contradiction to the previous proposal, we conclude that isomers in which an AuCN unit is directly bonded to the central Pd atom of PdAu8 are better candidates. This assignment was supported by Fourier transform infrared and ultraviolet–visible spectroscopies of isolated PdAu9CN. The simultaneous formation of [Au(PPh3)2]+ and PdAu9CN suggests that the AuCN species are formed by APP irradiation at the expense of a portion of PdAu8. These results indicate that APP may offer a unique method for transforming metal clusters into novel ones by generating in situ active species that were not originally added to the solution. [ABSTRACT FROM AUTHOR]

We report the resolution of a long-standing puzzle in molecular spectroscopy: the origin of the shoulder in the room temperature solution absorption spectrum of crystal violet (CV) - an archetypal cationic triphenylmethane dye. This was achieved by comparing experimental and theoretical results for CV in solution at room temperature and as an isolated cation in gas-phase at 5 K. The two lowest energy electronically excited states involved in the visible region absorption are degenerate and coupled via a Jahn--Teller (JT) mechanism involving phenyl torsions, making CV particularly sensitive to environmental perturbations. The shoulder is absent in the low-temperature isolated cation spectrum, and vibronic simulations based on time dependent density functional theory (TD-DFT) indicate negligible JT effects under these conditions. Combining vibronic simulations with molecular dynamics, demonstrates that in water and toluene solution at room temperature the shoulder arises mainly from an intermolecular, Jahn--Teller-like symmetry-breaking effect induced by the fluctuating electrostatic potential of the disordered solvent environment, rather than from molecular distortions. [ABSTRACT FROM AUTHOR]

Collision-induced dissociation and high-resolution cyclic ion mobility mass spectrometry, along with quantum chemical calculations and trajectory simulations, were used to compare the structures of isolated [MAu24(C≡CR)18]2−, M = Ni, Pd, or Pt, and their associated fragment ions. The three different alkynyl ligand-stabilized (C≡CR, R = 3,5-(CF3)2C6H3), transition metal-doped, gold cluster dianions showed mutually resolvable collision cross sections (CCS), which were ordered consistently with their molecular structures from X-ray crystallography. All three [MAu24(C≡CR)18]2− species fragment by sequential diyne loss to form [MAu24(C≡CR)18−n]2−, with n up to 12. The resultant fragment isomer distributions are significantly n- and M-dependent, and hint at a process involving concerted elimination of adjacent ligands. In particular [NiAu24(C≡CR)18]2− also fragments to generate alkyne-oligomers, an inference supported by the parallel observation of precursor dianion isomerization as collision energy is increased. [ABSTRACT FROM AUTHOR]

Helium tagging photodissociation action spectroscopy in the gas phase together with laser-induced fluorescence (LIF) spectroscopy in neon matrix has been used to probe the photophysics of electrosprayed rhodamine B cation cooled to < 5 K and studied in two different minimally perturbing environments ([RhB•He]+ as well as [RhB]+ in solid neon). Helium tagging experiments were performed using a newly developed apparatus He-TAG. LIF measurements were carried out using an improved matrix-isolation spectroscopy machine Depo-II. The resulting, partially vibrationally resolved electronic spectra of the S0→S1, resp. S1→S0 transition provide benchmarks for gauging the theoretical description of this prototypical organic dye. As a first approach, we have compared our spectra to TD-DFT-based predictions of vibronic structure at the Franck-Condon (FC) and Franck-Condon Herzberg-Teller (FCHT) levels. Depletion action and fluorescence spectroscopy of rhodamine B cation at < 5 K [ABSTRACT FROM AUTHOR]

The reactivity of Bin-clusters (n = 2 to 30) with O2 is found to display even-odd alternations. The open-shell even-sized Bin-clusters are more reactive than the closed-shell odd-sized clusters, except Bi18-, which exhibits no observable reactivity toward O2. We have investigated the structure and bonding of Bi18- to understand its remarkable resistance to oxidation. We find that the most stable structure of Bi18- consists of two Bi8 cages linked by a Bi2 dimer, where each atom is bonded to three neighboring atoms. Chemical bonding analyses reveal that each Bi uses its three 6p electrons to form three covalent bonds with its neighbors, resulting in a Bi18- cluster without any dangling bonds. We find that the robust Bi18 framework along with the totally delocalized unpaired electron is responsible for the surprising inertness of Bi18- toward O2. The Bi18 framework is similar to that in Hittorf's phosphorus, suggesting the possibility to create bismuth nanoclusters with interesting structures and properties. [ABSTRACT FROM AUTHOR]

To study the effect of a dye on the photoluminescence (PL) properties of metal complexes, a series of gold(I) complexes were synthesized, containing a 7‐amino‐4‐methylcoumarin luminophore. The complexes are comprised of a coumarin moiety featuring different ancillary ligands, specifically N‐heterocyclic carbenes, triphenylphosphine, and diphenyl‐2‐pyridylphosphine. The synthesized gold(I) complexes are luminescent both in solution and the solid state at room temperature and 77 K. Complexes of different nuclearity, i.e., mono‐, di‐ and trinuclear compounds were synthesized. A clear trend between the nuclearity and the quantum yields can be seen. The coumarin dye not only improves the PL properties, but also enhances the luminescence of trinuclear clusters, which are otherwise known to be weak emitters in solution. The optical absorption properties were investigated in detail by quantum chemical calculations. [ABSTRACT FROM AUTHOR]

The platinum hydride cluster Pt 12 H 24 - is studied in gas phase by a combination of trapped ion electron diffraction and density functional theory computations. We find a cuboctahedral platinum cage with bridge bound hydrogen atoms. This unusual structure is stabilized by Pt-H-Pt multicenter bonds and shows characteristics of spherical aromaticity., (© 2024 The Authors. ChemPhysChem published by Wiley-VCH GmbH.)

The reactivity of Bi n - clusters ( n = 2 to 30) with O 2 is found to display even-odd alternations. The open-shell even-sized Bi n - clusters are more reactive than the closed-shell odd-sized clusters, except Bi 18 - , which exhibits no observable reactivity toward O 2 . We have investigated the structure and bonding of Bi 18 - to understand its remarkable resistance to oxidation. We find that the most stable structure of Bi 18 - consists of two Bi 8 cages linked by a Bi 2 dimer, where each atom is bonded to three neighboring atoms. Chemical bonding analyses reveal that each Bi uses its three 6 p electrons to form three covalent bonds with its neighbors, resulting in a Bi 18 - cluster without any dangling bonds. We find that the robust Bi 18 framework along with the totally delocalized unpaired electron is responsible for the surprising inertness of Bi 18 - toward O 2 . The Bi 18 framework is similar to that in Hittorf's phosphorus, suggesting the possibility to create bismuth nanoclusters with interesting structures and properties.

Some of the authors of the present research group have previously reported mass spectrometric detection of [PdAu9(PPh3)8(CN)]2+ (PdAu9CN) by atmospheric pressure plasma (APP) irradiation of [MAu8(PPh3)8]2+ (PdAu8) in methanol and proposed based on density functional theory (DFT) calculations that PdAu9CN is constructed by inserting a CNAu or NCAu unit into the Au-PPh3 bond of PdAu8 [Emori et al., J. Chem. Phys. 155, 124312 (2021)]. In this follow-up study, we revisited the structure of PdAu9CN by high-resolution ion mobility spectrometry on an isolated sample of PdAu9CN with the help of dispersion-corrected DFT calculation. In contradiction to the previous proposal, we conclude that isomers in which an AuCN unit is directly bonded to the central Pd atom of PdAu8 are better candidates. This assignment was supported by Fourier transform infrared and ultraviolet-visible spectroscopies of isolated PdAu9CN. The simultaneous formation of [Au(PPh3)2]+ and PdAu9CN suggests that the AuCN species are formed by APP irradiation at the expense of a portion of PdAu8. These results indicate that APP may offer a unique method for transforming metal clusters into novel ones by generating in situ active species that were not originally added to the solution., (© 2024 Author(s). Published under an exclusive license by AIP Publishing.)

Collision-induced dissociation and high-resolution cyclic ion mobility mass spectrometry, along with quantum chemical calculations and trajectory simulations, were used to compare the structures of isolated [MAu 24 (CCR) 18 ] 2- , M = Ni, Pd, or Pt, and their associated fragment ions. The three different alkynyl ligand-stabilized (CCR, R = 3,5-(CF 3 ) 2 C 6 H 3 ), transition metal-doped, gold cluster dianions showed mutually resolvable collision cross sections (CCS), which were ordered consistently with their molecular structures from X-ray crystallography. All three [MAu 24 (CCR) 18 ] 2- species fragment by sequential diyne loss to form [MAu 24 (CCR) 18- n ] 2- , with n up to 12. The resultant fragment isomer distributions are significantly n - and M-dependent, and hint at a process involving concerted elimination of adjacent ligands. In particular [NiAu 24 (CCR) 18 ] 2- also fragments to generate alkyne-oligomers, an inference supported by the parallel observation of precursor dianion isomerization as collision energy is increased.