Diethylenetriamine-driven assembly of a dimeric cadmium bromide hybrid and an organic bromide salt: structural, vibrational, optical, in silico study and biological insights

Abstract

Diethylenetriamine (DET) was employed to synthesize two novel crystalline materials: a cadmium-based hybrid, (C₄H₁₆N₃)[CdBr₅]·H₂O (DETCdBr), and an organic salt, (C₄H₁₆N₃)Br₃ (DETBr). Single-crystal X-ray diffraction reveals that both crystallize in the monoclinic space group P2₁/c, with DETCdBr featuring [Cd₂Br₁₀]⁶⁻ dimeric units constructed from corner-sharing CdBr₆ octahedra, while DETBr consists of discrete ionic moieties stabilized by N–H⋯Br interactions. Complementary analyses (PXRD, SEM, FTIR, and Hirshfeld surface) confirm structural features, phase purity, and the dominant role of hydrogen bonding in both systems. Complementary in silico studies, including DFT calculations, ADME predictions, and molecular docking, confirm the electronic stability, reactive sites, and enzyme-binding potential of DETBr and DETCdBr. DETBr exhibits drug-like electronic properties with high solubility and favorable α-amylase interactions, while DETCdBr benefits from the cadmium scaffold, enhancing electrostatic and hydrogen-bonding contacts. Optical studies reveal a significant contrast: DETBr exhibits deep-UV absorption, whereas DETCdBr shows an extended absorption into the visible region with a reduced band gap (∼2.85 eV), attributed to metal–halide charge-transfer transitions. Both compounds display white-light photoluminescence with CIE coordinates near (0.32, 0.34) for DETCdBr and (0.30, 0.32) for DETBr. Biological assays demonstrate that both compounds inhibit α-amylase through distinct mechanisms: DETBr acts as a competitive inhibitor, while DETCdBr exhibits non-competitive behavior, highlighting the influence of structural organization on biological activity. These findings underline the role of metal coordination in tuning structural, optical, and functional properties.