Barwiolek, M.; Jankowska, D.; Kaczmarek-Kedziera, A.; Muziol, T.M.: Structural and optical properties of the p-alkylated 2,6-bis(benzimidazol)phenoles obtained from o-phenylenediamine and their sensitive behavior towards zinc(II) ions. Polyhedron 224 (2022), p. 116004/1-15
10.1016/j.poly.2022.116004
Abstract:
Two compounds, 2-hydroxy-5-methylisophthalaldehyde (L1) and 2-hydroxy-5-tert-butyl-1,3-benzenedicarboxaldehyde (L2), were obtained in the reaction between o-phenylenediamine and aldehydes. The X-ray crystal structure determination and DFT calculations aimed at the confirmation of the geometry of L1 and L2 in a solution and in the solid state were performed. The intermolecular interactions in the crystal structure of L1·0.5 CH3COOC2H5, L2·MeOH and L2·0.25 n-hexane were analyzed using the 3D Hirshfeld surfaces and related 2D fingerprint plots. The x-ray and 3D Hirschfeld analyses show the importance of the presence of the solvent in the crystal lattice. In L2·0.25 n-hexane, the solvent is only weakly bound, and only a robust network of Nsingle bondH…N and Csingle bondH…N hydrogen bonds that stabilise channels was noted. On the other hand, in the L2·MeOH, methanol forms a robust network of hydrogen bonds. The luminescence of L1 and L2 in various solvents and in the solid state was studied. In the solid state, emission was registered at 520 nm and 506 nm for L1 and L2, respectively. DFT calculations of the fluorescence spectra indicate green luminescence of the keto form of the compounds. Thin layers of the obtained compounds were deposited on Si(1 1 1) by the spin coating method and examined with scanning electron microscopy (SEM/EDS), atomic force microscopy (AFM) and fluorescence spectroscopy. The fluorescence sensing abilities of the compounds towards Zn2+ ions were evaluated. The experimental results showed that L1 and L2 could sensitively and efficiently detect Zn2+ ions (increase or decrease in the emission band at 443 nm for L1 or 434 nm for L2 (λex = 290) was observed).