Phase transitions, optical and electronic properties of the layered perovskite hybrid [NH3(CH2)2COOH ]2CdCl4 of Y-aminobutyric acid (GABA)

Highlights: • Complete structures data before and after the transition of [NH₃(CH₂)₃COOH]₂CdCl₄. • Phase transition Achiral ↔ Chiral. • The structure form infinite layers of (organic/inorganic) connected by Hydrogen bond. • Perfectly reversible first-order structural linked to reorientational motions and conformational changes of organic chains. • Comparison of energy gap value using the Kubelka–Munk function (Eg = 3.65 eV) with the theoretical energy gap (Eg = 3.336 eV). A new organic-inorganic hybrid with the formula (NH₃C₃H₆CO₂H)₂CdCl₄ has been crystallized and investigated by X-ray diffraction. Structural investigations highlight a first-order reversible structural phase transition occurring within the range (290–370 K) between a chiral (phase II) and non-centrosymmetric (Phase I) crystal packing. This strong structural reorganization is the result of conformational changes in the organic chains accompanied by a decrease in octahedral distortion. The accurate crystallographic analysis illustrates the crucial role of organic moieties. The experimental energy gap value (3.65 eV) is in good agreement with the theoretical value obtained by density functional theory.