1. PURPOSE Bacterial infection remains a serious threat to human lives because of their capacity to develop resistance to existing antibiotics, which is an increasing public health problem. For that reason, obtaining new types of antibacterial agents is a very important task. In this work, we reported the synthesis of new hydrazinecarbothioamides and 1,2,4-triazoles bearing 5H- dibenzo[a,d][7]annulene moiety and evaluated their antimicrobial activities. In conclusion, in this paper we described the synthesis, spectral characterization and antimicrobial activity of six new compounds possessing the 5H-dibenzo[a,d][7]annulene moiety. The new hydrazinecarbothioamides present two conformational isomers (axial and equatorial), which are interconvertible by middle ring inversion. Cyclization of hydrazinecarbothioamides in NaOH solution afforded the corresponding 1,2,4-triazoles- 3(4H)-thiole which were separated as pure axial isomers and exist in two tautomeric forms. The preliminary results of antimicrobial activities indicated that the tested compounds exhibited a moderate or low activity against tested strains. The new hydrazinecarbothioamides were synthesized using classical procedures, starting from 2-(5H-dibenzo[a,d][7]annulen- 5-yl)acetohydrazide. Cyclization of hydrazinecarbothioamides in NaOH solution afforded the corresponding 1,2,4-triazoles-3(4H)- thiol. The newly synthesized compounds were characterized by IR, 1 H NMR, 13 C NMR and elemental analysis. Their antimicrobial activities were evaluated against Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, Bacillus subtilis ATCC 6663, Salmonella tiphimurium ATCC 14028, Shigella flexneri ATCC 12022, Candida albicans ATCC 90028. Substituted hydrazinecarbothioamides and 1,2,4-triazoles as potential antimicrobial agents Laura-Ileana Socea 1, Gabriel Şaramet 1, Ştefania-Felicia Barbuceanu 1, Theodora-Venera Apostol 1, Bogdan Socea 2, Marina Panǎ 3 Manuela Anda Radu-Popescu 1 1 Carol Davila University of Medicine and Pharmacy, Faculty of Pharmacy, Bucharest, Romania 2 Carol Davila University of Medicine and Pharmacy, Faculty of General Medicine, Bucharest, Romania 3 Cantacuzino NIRDMI, Bucharest, Romania MATERIAL AND METHODS REZULTS CONCLUSIONS REFERENCE 1.L.I. Socea, T.V. Apostol, G. Şaramet, Ş.F. Bărbuceanu, C. Drăghici, M. Dinu, J. Serb. Chem. Soc., 2012, 77(11), 1541-1549; 2.I. Şaramet, A. Banciu, L. Socea, C. Drăghici, M.D. Banciu, Heterocyclic Communications, 2003, 9(6), 653-658. Acknowledgments This work was supported by University of Medicine and Pharmacy “Carol Davila” Bucharest, a project number 28331/04.11.2013. Comp S. aureus P. aeruginosa E. coli B. subtilis S. tiphimurium S. flexneri C. albicans 2a>10241024512>10241024512>1024 2b512256512>1024512 >1024 3a256512 128>1024512>1024 3b51264>1024 512 >1024 ν NH = 3141-3467cm -1 ν CO =1673-1681 cm -1 ν C=S =1253-1257 cm -1 IR DATA FOR NEW COMPOUNDS ANTIMICROBIAL ACTIVITY OF TESTED COMPOUNDS MIC (µg/mL) ν NH = 3130-3198 cm -1 ν C=N = 1561-1566cm -1 ν C=S = 1213-1245 cm -1 NMR DATA FOR NEW COMPOUNDS δ = 4.61-4.65 ppm (t) δ = 3.53-3.75 ppm (t) δ = 9.13-10.15 ppm (s) δ = 180.75-181.35 ppm δ = 169.99 -170.11 ppm δ = 10.97-11.58 ppm (s) δ = 151.50-152.06 ppmδ = 166.57-168.08 ppm