| Summary: | A new Ag(I)-azine complex of the formula [<b>Ag(L<sup>a</sup>)]<sub>2</sub>(ClO<sub>4</sub>)<sub>2</sub>.1/2(L<sup>b</sup>)</b> was synthesized and characterized using elemental analysis, FTIR, XPS and single-crystal X-ray diffraction. The [<b>Ag(L<sup>a</sup>)]<sub>2</sub>(ClO<sub>4</sub>)<sub>2</sub>.1/2(L<sup>b</sup>)</b> complex was obtained via Ag(I)-mediated hydrolysis of 2-(((1-(pyridin-2-yl)ethylidene)hydrazineylidene)methyl)phenol (<b>L</b>) with AgClO<sub>4</sub> leading to the formation of the azines (<i>1E,2E</i>)-1,2-<i>bis</i>(1-(pyridin-2-yl)ethylidene)hydrazine (<b>L<sup>a</sup></b>) and 2,2’-((<i>1E,1’E</i>)-hydrazine-1,2-diylidene <i>bis</i>(methanylylidene)) diphenol (<b>L<sup>b</sup></b>). The former underwent complexation with AgClO<sub>4</sub>, while the latter was co-crystallized with the resulting Ag(I) complex, leading to the complex formula [<b>Ag(L<sup>a</sup>)]<sub>2</sub>(ClO<sub>4</sub>)<sub>2</sub>.1/2(L<sup>b</sup>)</b>. In this complex, the azine <b>L<sup>a</sup></b> is acting as a bridged bidentate chelate connecting the two Ag(I) sites, leading to a tetra-coordinated Ag(I) with a distorted square planar coordination environment. Hirshfeld analysis indicated the importance of the H…H (38.4%), O…H (17.9%), H…C (13.2%), C…C (9.0%) and N…H (8.9%) interactions in the molecular packing. The antimicrobial, antioxidant and cytotoxic activities of the [<b>Ag(L<sup>a</sup>)]<sub>2</sub>(ClO<sub>4</sub>)<sub>2</sub>.1/2(L<sup>b</sup>)</b> complex were examined and compared with those of [<b>Ag(L<sup>a</sup>)]<sub>2</sub>(ClO<sub>4</sub>)<sub>2</sub></b>. The former was found to have lower bioactivity than the latter, which shed light on the lowering of biological actions as a consequence of the incorporation of the azine <b>L<sup>b</sup></b> within the Ag(I) complex. In other words, lowering the %Ag decreases the biological actions. The [<b>Ag(L<sup>a</sup>)]<sub>2</sub>(ClO<sub>4</sub>)<sub>2</sub>.1/2(L<sup>b</sup>)</b> complex (ΜIC = 39 μg/mL) has higher activity against the fungus <i>A. fumigatus</i> than the control Ketoconazole (ΜIC =156 μg/mL). This complex also has good cytotoxic activity against <i>colon carcinoma</i> and weak antioxidant activity.
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