Solvent-Directed Structural Diversity of Photoluminescent Zn(II) Metal-Organic Frameworks Based on 3-Aminoisonicotinate

Abstract

In this work, we present four metal-organic compounds based on Zn(II) ion and 3-aminoisonicotinic acid (H3isoani). Upon different synthetic conditions, three open 3D metal-organic frameworks of {[Zn(μ-3isoani)2]·4H2O}n (1), {[Zn(μ-3isoani)2]·2DMF}n (2) and {[Zn(μ-3isoani)2]·DMF}n (3) formulae and a fourth discrete coordination complex with [Zn(3isoani)2(H2O)4] (4) composition are obtained. All compounds can be interchanged with one another by adequate treatment of the samples under specific conditions. Furthermore, each compound showcases distinguished photoluminescent emission upon UV excitation, in such a way that the Zn-3isoani system exhibits variable emission along the composition. This variability in emission was measured at both room and low temperatures to assess the nuances of their photophysical behavior. Moreover, the emission properties are further elucidated by means of density functional theory (DFT) calculations, which provide insight into the underlying mechanisms governing their luminescent characteristics.