Supramolecular architectures constructed with the skeletons of zinc(II) 2,2′-bipyridine and barbiturate anion: Synthesis and characterization

The barbiturate 1,5-dihydro-5-[5-pyrimidine-2,4(1H,3H)-dionyl]-2H-chromeno[2,3-d] pyrimidine-2,4(3H)-dione) (LH4) 1 forms a complex with Zn(bpy)(NO3)2·2H2O (bpy = 2,2′-bipyridine) of composition [Zn(bpy)2(H2O)2]2+·(LH3)2·7H2O (2). In this structure, the ligand exists as anion (LH3-) as revealed by its single crystal X- ray crystallographic study. Packing studies of 2 provide three dimensional helical chains as secondary structure. However, its PXRD pattern shows that 2 does not retain its structure upon dehydration. Recrystallization of 2 from DMSO results in complex 3 with the composition [Zn(bpy)2(H2O)2]2+·(LH3-)2·DMSO·9H2O assigned on the basis of its elemental analysis and its X-ray crystallography. In order to understand the role of the 2,2′-bipyridine ring in the construction of supramolecular architecture, the reaction of zinc(II) nitrate salt with 1 is carried out to provide complex 4 of composition [Zn(LH3)2(H2O)4]·4H2O characterized by its single crystal X-ray diffraction study. Thermal, emission and photoluminescence properties of the complexes are also studied.

Graphical abstractA barbiturate derivative complexed with Zn(bpy)(NO3)2·2H2O and Zn(NO3)2·H2O provides fluorescent supramolecular architectures which are characterized by their single crystal X-ray crystallographic studies.Figure optionsDownload full-size imageDownload as PowerPoint slide