Positional isomerism of aminopiperidine regulates luminescence of Mn-doped Zn-based metal halides

Mn-doped Zn-based metal halides have attracted increasing attention for applications in white light-emitting diodes and X-ray detection, due to their structural stability and excellent luminescence performance. In this work, two positional isomers, 3-aminopiperidine (3AP) and 4-aminopiperidine (4AP), were selected as A-site organic cations to synthesize four zero-dimensional Zn-based halides, (3AP)Zn X 4 and (4AP)Zn X 4 ·H 2 O ( X  = Cl/Br). By incorporating Mn 2 + as luminescent centers, a series of highly efficient phosphors with narrow-band green emission were obtained. Spectroscopic comparisons show that the 4AP-based compounds exhibit better luminescence performance than those based on 3AP. According to Hirshfeld surface analysis, 4AP series features stronger hydrogen-bonding interactions, which enhance the structural rigidity of the crystal lattice and lead to higher photoluminescence efficiency and narrower full width at half maximum. Notably, three of the Mn-doped Zn-based compounds display pronounced X-ray radioluminescence, indicating they could be promising for X-ray detection and imaging applications.