University of Kashan Journal of Nanostructures 2251-7871 16 3 2026 07 01 Bottom-Up Synthesis of Nano-Organic Heterocyclic Antimicrobials Based on a Disulfide-Linked 1,2,3-Triazole Platform 3691 3705 115571 10.22052/JNS.2026.03.058 EN Marwan Majeed Al-Lammi Department of Pharmaceutical Chemistry, College of Pharmacy, Misan University, Iraq Helen Abd Alhassan Mahmood Department of Applied Chemistry, College of Applied Science, University of Fallujah, Iraq Sajida Munadi Th. AL‑Suraify Department of Pharmaceutical Chemistry, College of Pharmacy, Misan University, Iraq Journal Article 2026 03 27 The design of organic nanomaterials based on multi-heterocyclic nitrogen–sulfur scaffolds has recently emerged as a promising route to bioactive nano-derivatives that combine the chemical versatility of small molecules with the high surface-to-volume ratio of nanoscale solids. In this study, several new five-membered heterocyclic derivatives were synthesized through successive cyclization steps starting from hydrazone derivatives. The reaction of 5,5-dithiobis(1,3,4-thiadiazole-2-yl)-5-methyl-1H-[1,2,3]triazole-4-carboxylic acid with ethanol produced the ester (1). Treatment of the ester with hydrazine afforded the hydrazide (2), which was then used as a key intermediate for the construction of several five-membered ring systems. Reaction of (2) with acetylacetone furnished the pyrazole derivative (3). The hydrazide (2) was further converted into compound (4), which served as a pivotal precursor for the synthesis of a variety of five-membered heterocycles. In the presence of concentrated H₂SO₄, compound (4) was cyclized to give the thiadiazole derivative (5). Treatment of (4) with phenacyl bromide produced the thiazole derivative (6), while reaction with aqueous KOH and with pyridine afforded the triazole (7) and the oxadiazole (8) derivatives, respectively. Hydrazide (2) was also condensed with aromatic aldehydes to produce the Schiff bases (9) and (10), which on reaction with mercaptoacetic acid yielded the thiazolidinone derivatives (11) and (12). The structures of all the newly synthesized compounds were confirmed by UV, FT-IR, ¹H NMR and ¹³C NMR spectroscopic analyses. Furthermore, powder X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM) demonstrated that the synthesized derivatives were obtained directly in their nanocrystalline form, with average crystallite sizes in the range 28–62 nm calculated from the Debye–Scherrer equation, and with well-defined quasi-spherical, rod-like and flake-like nanoparticle morphologies. The thiazolidinone-based nano-derivatives (11) and (12) exhibited the strongest antibacterial and antifungal activities, comparable to the reference drugs, highlighting the potential of these organic nanomaterials as multi-target antimicrobial nano-agents. https://jns.kashanu.ac.ir/article_115571_339af81464e8b77d20d638218e8cac3d.pdf