Synthesis, molecular structure, mesomorphism and DFT/TD-DFT calculations of square-planar bis[1-((p-tolylimino)methyl)naphthalen-2-olato-κ2N,O]nickel and copper(II) complexes

Polymorphism, mesomorphism and anti-oxidant character of homoleptic bis[(E)-2-(1-((o-ethylphenyl)imino)ethyl)phenolato-κ2-N,O]Ni/Cu(ii) complexes

“…1, inset). 24,27,28,32,34,38 The absorption spectra were modelled using time-dependent density functional theory (TD-DFT) calculations using singlepoint calculations based on the DFT-optimized structures of 1 and 2 (Fig. 1 and Fig.…”

“…2). The Ni/Cu(II)-Schiff bases complexes in general can present both square-planar 28,32 and more pseudotetrahedral geometry. [24][25][26][27]29,38 Compounds 1 and 2a are isostructural, both solving in the triclinic space group P% 1.…”

“…Thermal analysis via differential scanning calorimetry (DSC) was used to probe phase transformation temperatures and the associated enthalpy changes (DH) for 1, microcrystalline 2 isolated from the reaction mixture, and crystallized samples of 2a and 2b. 24,29,[31][32][33] For the nickel complex 1, the DSC heating curve showed an endothermic peak at 246 1C (DH = À36.24 kJ mol À1 ) assigned to melting a crystalline solid to form isotropic liquid (Fig. 6a); upon cooling, an exotherm is evident at 134 1C (DH = +22.35 kJ mol À1 ) assigned to solidification of the isotropic liquid phase.…”

“…31 In contrast, homoleptic Ni/Cu(II) complexes of the same ligand (X = p-methyl) present square-planar geometry, as expected from simple ligand field considerations. 32 Similarly, mononuclear Rh(Z 4 -cod) Schiff base complexes of (E)-2-(1-((X-phenyl)imino)methyl)-phenol/-naphthalen-2-ol (X = H, oethyl) are also square planar. 33,34 For these complexes, which each crystallizes in a single morphology, thermal analysis by DSC and PLM reveal a simple phase transformation from crystalline solid to isotropic liquid, with the exception of the Cu(II) species 32 which exhibits mesomorphic properties.…”

“…32 Similarly, mononuclear Rh(Z 4 -cod) Schiff base complexes of (E)-2-(1-((X-phenyl)imino)methyl)-phenol/-naphthalen-2-ol (X = H, oethyl) are also square planar. 33,34 For these complexes, which each crystallizes in a single morphology, thermal analysis by DSC and PLM reveal a simple phase transformation from crystalline solid to isotropic liquid, with the exception of the Cu(II) species 32 which exhibits mesomorphic properties. In addition, no polymorphism was so far reported from these reported complexes.…”