Mechanochemical Synthesis and Co‐Former–Controlled Assembly of Azobenzene Polycarboxylate Organic Salts: From Framework Node to Passive Guest in HOF‐Like Architectures
Year: 2026
Type: article
Abstract: ABSTRACT Hydrogen‐bonded organic salts are versatile supramolecular materials whose architecture can be tuned through co‐former selection. Here, we report two multicomponent crystals of the azobenzene polycarboxylic acid 4,4′‐(diazene‐1,2‐diyl)bis(3,5‐dicarboxybenzoic acid) ( DADIA ): one with imidazole ( DADIA:IMD2 ) and one with N ‐methylimidazole ( DADIA:MeIMD ). Both were prepared by mechanochemical grinding followed by recrystallization from methanol. In each case, proton transfer from the carboxylic acid groups to the imidazole nitrogen gives charge‐assisted N + –H···O − hydrogen bonds, so the materials are best described as organic salts. Single‐crystal x‐ray diffraction shows that DADIA:IMD2 crystallizes in a monoclinic ( C2/c ) and DADIA:MeIMD in a triclinic ( P‐1 ), both forming two‐dimensional HOF‐like architectures. In DADIA:IMD2 , protonated imidazole acts as an active network node, generating channels occupied by disordered solvent. In DADIA:MeIMD , the 2D sheet is stabilized by O–H···O bonding between DADIA host molecules, with protonated N ‐methylimidazole housed in the pores as a passive guest. The compounds were further characterized by 1 H NMR, FT‐IR, PXRD, and TGA. These results show how a single N ‐methyl substituent switches the co‐former between the network node and the guest, with implications for gas storage, separation, and drug delivery.
DOI: 10.1002/poc.70121
Institutions: The University of Texas at Dallas, Radford University
Language: English
Subfield: Physical and Theoretical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W7225585351