Self-assembled supramolecular structures of O,N,N′ tridentate imidazole–phenol Schiff base compounds

Abstract

Three imidazole-derived Schiff base compounds comprising an N-methyl imidazole group coupled to a phenol ring through an imine bond were synthesised. The solid state and solution state supramolecular structures as well as energetics are explored.

N,N-bis(2-quinolinylmethyl)benzylamine

“…Inclusive of the two complementary hydrogen bonds, the loosely-held and puckered supramolecular cyclic motif of the dimer comprises 22 bonds, whose monomers are related by an imposed center of inversion. Similar structural packing in the solid, stabilized by dimeric conformations in the solid-state, has been reported for structurally related compounds [6,13,14]. The dimers form linear chains along the a-axis through another set of CH" .…”

Structural characterisation of novel mononuclear Schiff base metal complexes, DFT calculations, molecular docking studies, free radical scavenging, DNA binding evaluation and cytotoxic activity

“…The significant vibrational frequency of the aromatic hydroxyl group, disturbed by intramolecular hydrogen bonding between azomethine nitrogen atoms and phenolic hydrogen [O—H—N], may be responsible for the broad band at 3422 cm −1 in the free ligand. [ 35 ] The IR band of the free ligand at 1396 cm −1 , which disappeared after the complexation, was attributed to the δ(H 2 O) bending mode. The medium intense band observed at 1178 cm −1 in the ligand spectrum has been assigned to the stretching vibrations of the phenolic C–O, which, on complexation, shifted to higher wavenumbers from 1184 to 1197 cm −1 , implying other coordination through phenolic oxygen with metals.…”

Cation-/Ligand-Induced Solvent-Assisted Transformations of Zn(II) and Cu(II) Complexes Featuring Single-Pocket Multidentate Chelating Members

“…Over time, the inorganic chemistry community has progressively developed many unconventional routes to devise and prepare unique inorganic systems. The major significant synthetic impediment for inorganic chemists is frequently acquiring pure chelates and bringing forth their coordination to suitable metal centers or reactive metal precursors that allow for mild reaction conditions, short reaction times, and, most importantly, high yields and product purity. − This can be accomplished, for example, by employing renowned synthetic pathways such as cation-induced solvent-assisted (CISA) and ligand-induced solvent-assisted (LISA) transformation reactions. − Solvent-assisted transformations render one of the most indispensable strategies for preparing novel complexes which otherwise cannot be obtained via conventional routes. − Generally, solvent-assisted transformations admit to bond breaking/formation. − As such, self-assembly transitions can be reversible , or irreversible − depending either on thermodynamic or kinetic factors governing the metal’s reactivity (i.e., preferable coordination number and geometry, availability of d-orbitals, change in ionic radii, and oxidation state of the metal). − Furthermore, crystallographic transformations are highly desirable for comprehending structural changes. However, one major challenge is obtaining the crystalline phase of both the reactant and the product without crystal degradation, in which case, these solution-mediated transformations, more often than not, are accompanied by single-crystal to amorphous-phase transitions. , …”