New silver (thio)semicarbazide derivatives: Synthesis, structural features, and antimicrobial activity

Two novel semicarbazide [HL1, 1, 1-((4-nitrophenyl)(phenyl)methylene)semicarbazide] and thiosemicarbazide [HL2, 2, 1-((4-nitrophenyl)(phenyl)methylene)thiosemicarbazide] ligands were generated from 4-nitrobenzophenone and the corresponding (thio)semicarbazide precursors. Compounds 1 and 2 were fully characterized and their X-ray crystal structures were established. These organic derivatives were further applied as bioactive building blocks for the self-assembly synthesis of silver(i) coordination compounds. The reactions of silver(i) nitrate with HL1/HL2 in the presence of aqueous NH4OH resulted in new silver(i) coordination compounds formulated as [Ag(HL1)(NO3)]·H2O (3) and [Ag6(μ3-L2)6] (4). These complexes were characterized by standard methods (FT-IR, NMR, ESI-MS, and elemental analysis) as well as single-crystal X-ray diffraction. The structure of 3 features a two-coordinate silver(i) center with a distorted linear {AgNO} geometry, wherein an unusual coordination of HL1 through the nitrogen atom of the amine group is realized. The structure of 4 reveals a discrete Ag6 cluster composed of two joined trisilver(i) rings, wherein the three-coordinate Ag(i) centers adopt an {AgNS2} environment. The antimicrobial activity of 1-4 was screened against Gram-positive (S. epidermidis and S. aureus) and Gram-negative (P. aeruginosa and E. coli) bacteria. Compound 4 presented antimicrobial activity against Gram-positive bacteria, including the ability to impair biofilm formation. This study thus contributes to a still limited research area on the development of new silver coordination compounds with potential antibiofilm activity. © 2020 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.

Fernandes T.A.1, 2 , André V.1 , Arol A.S.1, 3 , França Â.4 , Mikhalyonok S.3 , Cerca N.4 , Kirillov A.M. 1, 5
Royal Society of Chemistry
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  • 1 Centro de Química Estrutural, Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, Lisboa, 1049-001, Portugal
  • 2 Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa Campo Grande, Lisboa, 1749-016, Portugal
  • 3 Department of Organic Chemistry, Belarusian State Technological University, 13a Sverdlova St., Minsk, 220006, Belarus
  • 4 Centre of Biological Engineering, University of Minho Campus de Gualtar, Braga, 4710-057, Portugal
  • 5 Research Institute of Chemistry, Peoples' Friendship University of Russia (RUDN University), 6 Miklukho-Maklaya st., Moscow, 117198, Russian Federation
Ammonium hydroxide; Complexation; Coordination reactions; Crystal atomic structure; Escherichia coli; Single crystals; Anti-microbial activity; Coordination compounds; Gram-positive bacterium; Organic derivatives; Self-assembly synthesis; Semicarbazide derivative; Single crystal x-ray diffraction; X ray crystal structures; Silver compounds; 1 [(4 nitrophenyl)(phenyl)methylene]semicarbazide; 1 [(4 nitrophenyl)(phenyl)methylene]thiosemicarbazide; 4 nitrobenzophenone; amine; antiinfective agent; benzophenone derivative; coordination compound; nitrogen; semicarbazide derivative; silver; silver nitrate; thiosemicarbazide derivative; unclassified drug; antimicrobial activity; Article; biofilm; carbon nuclear magnetic resonance; complex formation; controlled study; crystal structure; drug screening; drug structure; drug synthesis; electrospray mass spectrometry; elemental analysis; Escherichia coli; Fourier transform infrared spectroscopy; geometry; minimum inhibitory concentration; nonhuman; priority journal; proton nuclear magnetic resonance; Pseudomonas aeruginosa; Staphylococcus aureus; Staphylococcus epidermidis; X ray; X ray diffraction
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