Mono‐ and penta‐nuclear self‐assembled silver(I) complexes of pyrazolyl s ‐triazine ligand; synthesis, structure and antimicrobial studies

The self‐assembled [Ag (PTDM)NO 3 ] ( 1 ), [Ag (PTDM) 2 (H 2 O)]ClO 4 . H 2 O ( 2 ) and [Ag 5 (PTDM) 4 (H 2 O) 6 (ClO 4 ) 4 ]ClO 4 . 2H 2 O ( 3 ) complexes were synthesized by the direct mixing of AgX (X = NO 3 ¯ or ClO 4 ¯) and 4,4′‐[6‐(3,5‐dimethyl‐ 1H ‐pyrazol‐1‐yl)‐1,3,5‐triazine‐2,4‐diyl]dimorpholine ( PTDM ) ligand in water–methanol mixture. The coordination numbers of silver range from three to five. Complex 3 is a rare case in which one nitrogen atom from the same s ‐triazine core of the PTDM ligand has a μ (1,1) bridging mode between Ag1 and Ag2 in the penta‐nuclear array with Ag1–N1 and Ag2–N1 distances of 2.666(4) and 2.418(3) Å, respectively. Its 3D topology has a kind of primitive dense packing derived from the α ‐Po type structure. Hirshfeld analysis showed that the percentages of the O … H hydrogen bonds were 32.4, 25.4, and 42.0% in complexes 1 – 3 , respectively. While the ligand showed no antimicrobial activity at the applicable concentration, the penta‐nuclear complex 3 had higher antibacterial (MIC = 3.7 μmol/L) and antifungal (14.6 μmol/L) potencies toward the tested microbes compared with complexes 1 and 2 . Also, the killing doses of 3 were in the range of 7.3–58.5 μmol/L compared with 18.2–291.1 and 20.1–160.6 μmol/L for 1 and 2 , respectively. It is clear that the higher Ag‐content in 3 could be the main reason for its higher antimicrobial activity.