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A synergic approach combining molecular dynamics (MD) simulations and X-ray absorption spectroscopy has been used to investigate diluted solutions of zinc bis(trifluoromethanesulfonyl)imide (Zn(TfN)) in TfN based ionic liquids (ILs) having different organic cations, namely the 1-butyl-3-methylimidazolium ([C(mim)]), 1,8-bis(3-methylimidazolium-1-yl)octane ([C(mim)]), N,N,N-trimethyl-N-(2-hydroxyethyl)ammonium ([Choline]) and butyltrimethylammonium ([BTMA]) ions. All of the ILs tend to dissolve the Zn(TfN) species giving rise to a different structural arrangement around the Zn as compared to that of the salt crystallographic structure. A quantitative analysis of the Zn K-edge extended X-ray absorption fine structure (EXAFS) spectra of the solutions has been carried out based on the microscopic description of the systems derived from the MD simulations. A very good agreement between theoretical and experimental EXAFS signals has been obtained, allowing us to assess the reliability of the MD structural results for all the investigated solutions. The Zn ion has been shown to be coordinated by six oxygen atoms of the TfN anions arranged in an octahedral geometry in all the TfN based ILs, regardless of the organic cation of the IL solvent. However, the nature of the organic cation has a small influence on the overall spatial arrangement of the TfN anions in the Zn first solvation shell: two different Zn-TfN complexes are found in solution, a 5-fold one, with one bidentate and four monodentate TfN anions, and a 6-fold one with only monodentate ligands, with the ratio between the two species being slightly dependent on the IL cation. The IL ion three-dimensional arrangements in the different IL solutions were also investigated by carrying out a thorough analysis of the MD simulations, highlighting similarities and differences between imidazolium and ammonium based IL systems.

An elusive tetrahedral hydration structure for bromide in aqueous solution has been unveiled through the use of ab initio molecular dynamics. It has been revealed that a subset of first shell water molecules has a preferential strong interaction with the ion lone pairs, giving rise to a tetrahedral short-lived complex. Through the use of a new geometric descriptor correlated to the ion-water pair interaction energy, we managed to divide the conventional first hydration shell into a tight first shell and a loose first shell, highlighting their different structural and dynamic behavior. This picture suggests the mandatory role of lone pairs in the study of highly disordered systems where the hydrogen bond is the most relevant interaction in the solvation process, such as weakly hydrated anions. This interaction-based approach leads to an improvement in the description of halide hydration given up to now by radial models.

The band-gaps of CsPbI 3 perovskite nanocrystals are measured by absorption spectroscopy at cryogenic temperatures. Anomalous band-gap shifts are observed in CsPbI 3 nanocubes and nanoplatelets, which are modeled accurately by band-gap renormalization due to lattice vibrational modes. We find that decreasing dimensionality of the CsPbI 3 lattice in nanoplatelets greatly reduces electron-phonon coupling, and dominant out-of-plane quantum confinement results in a homogeneously broadened absorption lineshape down to cryogenic temperatures. An absorption tail forms at lowtemperatures in CsPbI 3 nanocubes, which we attribute to shallow defect states positioned near the valence band-edge.