Tunable Ambroxol-based luminescent materials: Syntheses, crystal structure and Hirshfeld surface analysis

Two new salts with ambroxol moieties, namely, [HAX](+) TR- nH(2)O (TR ?= ?OA (n ?= ?0 (1), PA (n ?= ?1) (2)) [AX ?= ?4-((2-amino-3,5-dibromobenzyl)amino) cyclohexan-1-ol, OA ?= ?o-chloro-benzoic acid, PA ?= ?p-chloro-benzoic acid], were obtained by the reaction of AX and two organic aromatic acids, respectively. The emission maxima can be found at 467 and 475 ?nm for compounds 1 and 2 in the solid state at room temperature, respectively. Compared with the free AX, the red-shifted values are about 81 and 89 ?nm for compounds 1 and 2, respectively, indicating that the emission maxima are proportional to the intermolecular packing interactions. Compounds 1 and 2 were structurally characterized by X-ray single crystal diffraction, EA, UV-Vis and FT-IR spectra. Single crystal X-ray diffraction reveals that the order of pi center dot center dot center dot pi stacking interactions is consistent with that of luminescent peaks. The Hirshfeld surface analysis confirm that the H center dot center dot center dot H and C center dot center dot center dot H/H center dot center dot center dot C close contacts can account for the luminescent behaviors. The close contacts of Br center dot center dot center dot H/H center dot center dot center dot Br, O center dot center dot center dot H/H center dot center dot center dot O and Cl center dot center dot center dot H/H center dot center dot center dot Cl can be responsible for the melting points of both compounds. Additionally, the thermal properties for compounds 1 and 2 have been discussed in detail.