Quantum chemical and X-ray diffraction studies of (E)-3-(((3,4-dimethoxybenzyl)imino)methyl)benzene-1,2-diol

Synthesis of Novel Aqua ƞ4-NNNO/Cu(II) Complexes as Rapid and Selective Oxidative Catalysts for O-Catechol: Fluorescence, Spectral, Chromotropism and Thermal Analyses

“…The de-colorization process was pursued by spectrophotometric titration, revealing a consumption of mainly four equivalent protons from HCl at λmax = 625. This outcome agrees with the protonation nature of the tetradentate ligand to furnish the protonated ligand [14][15][16][17][18][19][20][21][22][23][24][25][26] and the hydrated copper salt (CuBr2) (Figure 7b). Due to solubility limitation of complex 2 for the solvatochromism study, a number of solvents such as water, methanol, DMSO and DMF were investigated.…”

“…Due to the ability of the Cu(II) center to form five-coordinate complexes, a stable trigonal bipyramidal geometry has been suggested as shown in Scheme 1. Moreover, Cu(II) center has been reported to make six bonds, where water as a moderate ligand plays a complementary role in forming six or five coordination numbers [18][19][20][21][22][23][24][25]. Notably, our ligand and its Cu(II) complexes showed high stability in addition to adequate solubility in typical polar solvents such as water, MeOH, DMSO and DMF.…”

“…The measured FT-IR transmissions of starting materials, tetradentate ligand and complex 1 are shown in Figure 2. Initially, the absence of O-H stretching band in the range of 3100-3500 cm −1 in both 5-fluoro-2-hydroxyacetophenone starting material and its ligand could be rationalized to the robust intramolecular H-bonding [18][19][20][21][22] with C-OH and C=N groups. The two weak vibrational bands at 3359 and 3277 cm −1 from piperazinyl-ethylamine group were evanesced due to the formation of SB functional moiety.…”

“…As this ligand compound denotes an appropriate multi-dentate position via the O,N-donor atoms, the coordination with three copper(II) precursors in the absence of base was accomplished smoothly and in good yields. Exceptional chemotropism properties are expected to be demonstrated by the complexes under different conditions and physical states, due to the proton-transfer from the 2-hydroxyaryl group to the attached imine moiety on SB skeleton [16][17][18][19][20][21]. Hence, the chemotropism (solvent, ion, thermal), florescence and thermal behaviors of the SB ligand and the three new copper(II) complexes were examined.…”

Crystal structure and spectral of new hydrazine-pyran-dione derivative: DFT enol↔hydrazone tautomerization via zwitterionic intermediate, hirshfeld analysis and optical activity studies

“…The thermochromism and photochromism are remarkable features can be displayed by the Schiff base (SB) functional groups in the solid state. These features are normally resulting from a proton-transfer from the o-hydroxyaryl group to the attached imine moiety [9]. Depending on the substitutions and the electronic conditions, the o-hydroxyaryl SB compounds could be present either in the keto form, enol form, keto/enol mixtures or scarcely in the zwitterionic form.…”