Metal complexes of N-(7-hydroxyl-4-methyl-8-coumarinyl)- amino acid, N-(2-pyridylmethyl)-amino acid and related ligands: Synthesis, structural, photophysical and gelation properties

Abstract

Considerable efforts have been devoted to the studies of rational design, functional properties and applications of crystalline materials while the discovery of gels has been largely serendipitous at the initial stages. Recently, researchers developed that it is possible to design the gelation process which offers new insight in the studies and applications of the functional materials.This study presents the synthesis, characterization, structural and gelation studies of transition and main group complexes of 4-methylumbelliferone-8-methyleneiminodiacetic acid (A), N-(7-hydroxyl-4-methyl-8-coumarinyl)-amino acid (B) and N-(2-pyridylmethyl)-amino acid (C) ligands. Complexes of A and C exhibit diverse and fascinating structural architectures including monomeric, ion-pair and coordination polymer. Complexes of B self-assembled into crystalline and amorphous gel-phase materials. Interestingly, Zn(II) and Mg(II) hydrogels can be fabricated in the absence of long chain hydrophobic groups and exhibit strong blue fluorescence. In summary, this work provides more insight into the self-assembly process of crystalline and amorphous gel materials.