Theoretical and experimental study of new hybrid compound rich in hydrogen bonding: 2-carboxyanilinium hypophosphite

Phonon properties and mechanism of order-disorder phase transition in formamidinium manganese hypophosphite single crystal

The detailed temperature-dependent IR and Raman spectra were used to study and understand the mechanism of structural phase transition occurring at 175 K in manganese hypophosphite templated with formamidinium (FA⁺) ions, [FA]Mn(H₂POO)₃, which adopts a perovskite-like architecture. The structural transformation between the C2/c and the P2₁/c monoclinic phases has a complicated nature and is mainly driven by re-orientational motions of the FA⁺ cations but it is also accompanied by a significant distortion of the MnO₆ octahedral units as well as steric-forced changes of the PH₂ groups determining the off-center shifts of FA⁺ cations in the cages. The re-orientational motions of formamidinium cations at 175 K are followed by slight changes of their geometry and re-arrangement of hydrogen bonds (HBs). The strong temperature-dependences of bands corresponding to vibrations involving hydrogen bonding reveal the highly-dynamic character of this phase transition and strong nature of created HBs. The most pronounced changes are observed for the modes corresponding to the formamidinium cation, proving that the phase transition has an order-disorder character.

A mechanism of the luminescent covalent organic framework for the detection of NH3

The comparison of the two systems shows that the addition of NH₃ can affect the luminescence behavior of Ph-An-COF.