Effect of the substituted location on luminescent behaviors with Ambroxol moieties: Synthesis, crystal structure and Hirshfeld surface

To further exploit the new materials, a set of new salts containing ambroxol and hydroxyl aromatic car-boxylate moieties, namely, [HAXE]+ B - ( B = MSA ( 1 ), 23A ( 2 ) and 26A ( 3 )) [AXE = 4-((2-amino-3,5-dibromobenzyl)amino) cyclohexan-1-ol, MSA = 5-methyl salicylic acid, 23A = 2-hydroxy-3-naphthoic acid, and 26A = 2-hydroxy-6-naphthoic acid], were obtained by the reaction of AXE and a set of aro -matic carboxylic acid, respectively. The emission maxima can be found at 386, 445, 523 and 452 nm for AXE and its compounds 1 -3 in the solid state at room temperature, respectively. Compared with the free AXE, the emission maxima of compounds 1 -3 are obviously red-shifted about 59, 137 and 66 nm, respec-tively, revealing that the intermolecular packing interactions affect the emission maxima. Compounds 1 -4 were structurally characterized by X-ray single crystal diffraction and FT-IR. Single crystal X-ray diffrac-tion analysis shows that there exist pi center dot center dot center dot pi packing interactions and a set of hydrogen bonds. The shortest distances of pi center dot center dot center dot pi stacking interactions are 3.693(6) and 3.86(2) angstrom in compounds 2 and 3 , respectively. The Hirshfeld surface analysis reveals that the order of the C center dot center dot center dot H/H center dot center dot center dot C close contacts coincides with that of the luminescent maxima. Meanwhile, the intermolecular contacts of O center dot center dot center dot H/H center dot center dot center dot O and N center dot center dot center dot H/H center dot center dot center dot N can quantitatively account for the melting points of these compounds. Additionally, the thermal properties of compounds 1-3 were estimated in detail.(c) 2023 Elsevier B.V. All rights reserved.