Synthesis, structural characterization, spectroscopic, and DFT studies of two penta-coordinated zinc(II) complexes containing quinazoline and 1, 10-phenanthroline as mixed ligands

Publication date: November 2018
Source:Journal of Luminescence, Volume 203
Author(s): Lan-Qin Chai, Qi Hu, Kong-Yan Zhang, Ling Zhou, Jiao-Jiao Huang
Two 2-D and 3-D supramolecular zinc(II) complexes, [Zn(L1)(phen)(NO3)2] (1) and [Zn(L3)(phen)(NO3)2] (2), have been synthesized via complexation of salt nitrate hexahydrate with quinazoline-type ligands and 1,10-phenanthroline, where HL1 = 4-methyl-2-(4-nitrophenyl)-1,2-dihydroquinazoline 3-oxide, HL3 = 2-(4-cyanophenyl)-4-methyl-1,2-dihydroquinazoline 3-oxide (H is the deprotonatable hydrogen). The plausible reaction mechanism for the formation of 4-methyl-2-(4-nitrophenyl)quinazoline 3-oxide (HL2) was proposed. These compounds were synthesized and characterized by IR, UV–Vis, and fluorescence spectroscopy, as well as by elemental analysis, respectively. The spectroscopic data of both complexes were compared with the ligands HL1 and HL3. The single crystal X-ray structures of HL2 and both complexes were determined. X-ray single crystal analyses reveal that both complexes have penta-coordinated geometry and form an infinite 2-D and 3-D supramolecular frameworks through classical H-bonding and π···π stacking interactions. The normalized fluorescent spectra show clearly that complexes 1 and 2 have favourable fluorescent emissions in different solvents. In addition, the calculated HOMO and LUMO energies show the character of complexes 1 and 2. The electronic transitions and spectral features of complexes 1 and 2 were discussed by TD-DFT calculations.

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