Crystal structures of salen-type ligands 2-[(1E)-({1-(3-chloro-phen-yl)-2-[(E)-(2-hy-droxy-benzyl-idene)amino]-prop-yl}imino)-meth-yl]phenol and 2-[(1E)-({1-(4-chloro-phen-yl)-2-[(E)-(2-hy-droxy-benzyl-idene)amino]-prop-yl}imino)-meth-yl]phenol

Synthesis, crystal structure, stereochemical and Hirshfeld surface analysis of trans-di-aqua-bis-(1-phenyl-propane-1,2-di-amine-κ2N,N')nickel(II) dichloride dihydrate

In the hydrated complex salt, [Ni(C9H14N2)2(H2O)2]Cl2·2H2O, the asymmetric unit comprises of half of the complex cation along with one chloride anion and one non-coordinating water mol-ecule. The central nickel(II) atom is located on an inversion center and is coordinated in a trans octa-hedral fashion by four N atoms from two bidentate 1,2-di-amino-1-phenyl-propane ligands in the equatorial plane, and by two oxygen atoms from two water mol-ecules occupying the axial sites. The five-membered chelate ring is in a slightly twisted envelope conformation. The crystal packing features O-H⋯Cl, N-H⋯O and N-H⋯Cl hydrogen bonds. Hirshfeld surface analysis revealed that the most important contributions to the crystal packing are from H⋯H (56.4%), O⋯H/H⋯O (16.4%) and H⋯Cl (13.3%) inter-actions. The crystal void volume was calculated to be 15.17%.

A Water-Soluble Schiff Base Turn-on Fluorescent Chemosensor for the Detection of Al3+ and Zn2+ Ions at the Nanomolar Level: Application in Live-Cell Imaging

A water-soluble Schiff base, 2,3-bis((E)-(2-hydroxy-3-methoxybenzylidene)amino) propanoic acid (ODA) prepared by condensing o-vanillin and DL-2,3-diaminopropionic acid was evaluated as an efficient "turn on" fluorescent chemosensor for the selective recognition of Al3+ and Zn2+ ions in presence of several interfering metal ions (detection limit; for Al3+ = 1.82 nM, Zn2+ = 7.06 nM). The probe also shows a selective chromogenic behavior towards Al3+ and Zn2+ ions that the naked eye can view. The binding stoichiometry was determined using 1H-NMR titration and ESI-MS spectrometry. The sensing mechanism is due to the inhibition of ESIPT and isomerization of -C=N of ODA on complexation with Al3+/Zn2+. The intramolecular hydrogen bonding energy and the critical bond energy in ODA-Al3+/Zn2+ were calculated using QTAIM analysis. The Thin Layer Chromatography (TLC) plates and strip papers loaded with ODA were used to test the practical applications for sensing Al3+ and Zn2+ ions. Moreover, the probe has been used for live-cell imaging to detect Al3+ and Zn2+ ions in hepatoma C3A and human glioblastoma U87 cells.