Electronic States of Tris(bipyridine) Ruthenium(II) Complexes in Neat Solid Films Investigated by Electroabsorption Spectroscopy.

We present the electric field-induced absorption (electroabsorption, EA) spectra of the solid neat films of tris(bipyridine) Ru(II) complexes, which were recently functionalized in our group as photosensitizers in dye-sensitized solar cells, and we compare them with the results obtained for an archetypal [Ru(bpy)3]2+ ion (RBY). We argue that it is difficult to establish a unique set of molecular parameter values by discrete parametrization of the EA spectra under the Liptay formalism for non-degenerate excited states. Therefore, the experimental EA spectra are compared with the spectra computed by the TDDFT (time-dependent density-functional theory) method, which for the first time explains the mechanism of electroabsorption in tris(bipyridine) Ru complexes without any additional assumptions about the spectral lineshape of the EA signal. We have shown that the main EA feature, in a form close to the absorption second derivative observed in the spectral range of the first MLCT (metal-to-ligand charge transfer) absorption band in Ru(bpy)3(PF6)2, can be attributed to a delocalized and orbitally degenerate excited state. This result may have key implications for the EA mechanism in RBY-based systems that exhibit similar EA spectra due to the robust nature of MLCT electronic states in such systems.

Gas-phase generation of dinuclear Au(I)-Au(II) complexes by laser desorption ionization mass spectrometry.

Alkali metal chloroaurates(III) were analysed by laser desorption ionization mass spectrometry. Among a number of generated gas-phase ionic clusters, the unusual ions [MAu2Cl5]- (were M stands for Na, K, Rb, Cs) were detected. The spectra of metastable ions and quantum mechanics calculations show the presence of unprecedented Au(I)-Au(II) interactions in the clusters.

Methyl group transfer upon gas phase decomposition of protonated methyl benzoate and similar compounds.

Gas phase decompositions of protonated methyl benzoate and its conjugates have been studied by using electrospray ionization-collision induced dissociation-tandem mass spectrometry. Loss of CO2 molecule, thus transfer of methyl group, has been observed. In order to better understand this process, the theoretical calculations have been performed. For methyl benzoate conjugates, it has been found that position of substituent affects the loss of CO2 molecule, not the electron donor/withdrawing properties of the substituent. Therefore, electrospray ionization-mass spectrometry in positive ion mode may be useful for differentiation of isomers of methyl benzoate conjugates.

Formation of organometallic species, [M - H](+) ions and radical cations upon mass spectrometric fragmentation of mercury-crown ether complexes.

Mass spectrometric fragmentation pathways of [M + HgClO(4)](+) (M - crown ether molecule), determined by tandem mass spectrometry experiments, are discussed in detail. The decomposition of [M + HgClO(4)](+) proceeds along three fragmentation pathways: formation of [M - H](+) ions, formation of organometallic species, namely [M - H + Hg](+) ions, and formation of radical cations [M](+*). The factors influencing these processes, namely crown ether cavities and the presence of electron withdrawing/electron donor groups, have been discussed.

Anion-pi interactions-interactions between benzo-crown ether metal cation complexes and counter ions.

The loss of X(.) radical from [M + Cu + X](+) ions (copper reduction) has been studied by the so called in-source fragmentation at higher cone voltage (M = crown ether molecule, X(-) = counter ion, ClO(4)(-), NO(3)(-), Cl(-)). The loss of X(.) has been found to be affected by the presence/lack of aromatic ring poor/rich in electrons. Namely, the loss of X(.) occurs with lower efficiency for the [NO(2)-B15C5 + Cu + X](+) ions than for the [B15C5 + Cu + X](+) ions, where NO(2)-B15C5 = 3-nitro-benzo-15-crown-5, B15C5 = benzo-15-crown-5. A reasonable explanation is that Anion-pi interactions prevent the loss of X(.) from the [NO(2)-B15C5 + Cu + X](+) ions. The presence of the electron-withdrawing NO(2) group causes the aromatic ring to be poor in electrons and thus its enhances its interactions with anions. For the ion containing the aromatic ring enriched in electrons, namely [NH(2)-B15C5 + Cu + ClO(4)](+) where NH(2)-B15C5 = 3-amino-benzo-15-crown-5, the opposite situation has been observed. Because of Anion-pi repulsion the loss of X(.) radical proceeds more readily for [NH(2)-B15C5 + Cu + X](+) than for [B15C5 + Cu + X](+). Iron reduction has also been found to be affected by Anion-pi interactions. Namely, the loss of CH(3)O(.) radical from the ion [B15C5 + Fe + NO(3) + CH(3)O](+) proceeds more readily than from [NO(2)(-)B15C5 + Fe + NO(3) + CH(3)O](+).