Structural characterization, thermal, dielectric, vibrational properties and molecular dynamics of (C5H5NH)3BiCl6

Internal Vibrations of Pyridinium Cation in One-Dimensional Halide Perovskites and the Corresponding Halide Salts

We investigate vibrations of the pyridinium cation PyH+ = C5H5NH+ in one-dimensional lead halide perovskites PyPbX3 and pyridinium halide salts PyHX (X- = I-, Br-), combining infrared absorption and Raman scattering methods at room temperature. Internal vibrations of the cation were assigned based on density functional theory modeling. Some of the vibrational bands are sensitive to perovskite or the salt environment in the solid state, while halide substitution has only a minor effect on them. These findings have been confirmed by 1H, 13C and 207Pb solid-state nuclear magnetic resonance (NMR) experiments. Narrower vibrational bands in perovskites indicate less disorder in these materials. The splitting of NH-group vibrational bands in perovskites can be rationalized the presence of nonequivalent crystal sites for cations or by more exotic phenomena such as quantum tunneling transition between two molecular orientations. We have shown how organic cations in hybrid organic-inorganic crystals could be used as spectators of the crystalline environment that affects their internal vibrations.

Crystal structure, spectroscopic measurement, optical properties, thermal studies and biological activities of a new hybrid material containing iodide anions of bismuth(iii)

As part of our interest in halogenobismuthate(iii) organic-inorganic hybrid materials, a novel compound named bis(4,4'-diammoniumdiphenylsulfone) hexadecaiodotetrabismuthate(III) tetrahydrate with the chemical formula (C₁₂H₁₄N₂O₂S)₂[Bi₄I₁₆]·4H₂O, abbreviated as (H₂DDS)[Bi₄I₁₆], has been prepared by a slow evaporation method at room temperature. This compound was characterized by single crystal X-ray diffraction (SCXRD), spectroscopic measurements, thermal study and antimicrobial activity. The examination of the molecular arrangement shows that the crystal packing can be described as made of layers of organic [C₁₂H₁₄N₂O₂S]²⁺ entities and H₂O molecules, between which tetranuclear [Bi₄I₁₆]^4- units, isolated from each other, are inserted. The cohesion among the different molecules is assured by N-H⋯I, N-H⋯O and O-H⋯I hydrogen bonding interactions, forming a three-dimensional network. Room temperature IR, Raman spectroscopy of the title compound were recorded and analyzed. The optical properties were also investigated by both UV-vis and photoluminescence spectroscopy. Moreover, the synthesized compound was also screened for in vitro antimicrobial (Gram-positive and Gram-negative) and antioxidant activities (scavenging effect on DPPH free radicals, reducing power and total antioxidant capacity).

Correlation between crystal structures and polar (ferroelectric) properties of hybrids of haloantimonates(iii) and halobismuthates(iii)

Halogenoantimonates(iii) and halogenobismuthates(iii) are a highly versatile class of organic–inorganic hybrid materials, applicable in optoelectronics and switchable dielectric devices.

Binuclear Bi(iii) halide complexes with 4,4′-ethylenepyridinium cations: luminescence tuning by reversible solvation

New binuclear chloride and bromide complexes of Bi(iii) demonstrate strong reversible solvatochromism.

Unusual IR ring mode splittings for pyridinium species in H3PW12O40 heteropolyacid: involvement of the δNH internal mode

This study aimed at investigating the well-known infrared band splitting affecting the ν8b and ν19b modes of pyridinium species formed by pyridine absorption in tungsten heteropolyacid H₃PW₁₂O₄₀, first reported 30 years ago but the origin of which has not yet been satisfactorily explained.