The redox-active azothioformamide (ATF) ligand has shown a unique ability to coordinate and/or dissolve various transition metals and metal salts in multiple oxidation states through a 1,4-heterodiene alpha-azothiocarbonyl moiety. It was hypothesized that by modifying the electronics of these systems, the redox-activity and binding associations of the ligand could be altered. A small library of para-substituted aryl ATF ligands (from electron donating to electron withdrawing) and alkyl-ATFs were prepared, characterized, and then reacted with copper(I) salts yielding crystalline material. Single crystal X-ray diffraction, UV-Vis titrations, and computational calculations were performed to assess the degree of coordination and the effects of substitution on the ligand: metal binding. Based on non-linear binding association constants, relative strength of coordination was of the order CH3O-ATF &gt; CH3-ATF &gt; ATF ≈ F-ATF &gt; CN-ATF &gt; CF3-ATF for para-substituted aryl species with strong correlation to both asymmetric and symmetric 2:1 binding models. The alkyl-ATF species fit best in a 2:1 Full binding model. Further variations on the placement of the substituted groups (ortho, and meta) are now being explored with various metals, and the complexes for potential catalysis and biological activity.

Evaluating supramolecular coordination of azothioformamide (ATF) ligands with copper(I) salts

ACS Spring Meeting 2021

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