Experimental and Theoretical Evaluation of Four NLO‐Active Divalent Transition Metal Complexes Supported by an Enantiomerically Pure Tetradentate Schiff Base Ligand

AUTHORS

• Celedon Salvador
• Hamon Paul
• Artigas Vania
• Fuentealba Mauricio
• Kahlal Samia
• Ledoux-Rak Isabelle
• Carrillo David
• Saillard Jean-Yves
• Manzur Carolina
• Hamon Jean-René

KEYWORDS

Chiral Schiff bases

Density functional calculations

Nonlinear optics

Transition metals

X-ray diffraction

Document type

Journal articles

Résumé

This paper reports on a series of five chiral Schiff base push-pull compounds derived from enantiomerically pure (1R,2R)-(−)-1,2-diaminocyclohexane. The NiII, CuII, ZnII and PdII complexes supported by a ferrocene-containing unsymmetrically-substituted N2O2 quadridentate Schiff base ligand were prepared via template reactions and isolated in 74-87% yields. A combination of EA, IR, UV/vis and 1H/13C{1H} NMR spectroscopy, HRMS spectrometry, cyclic voltammetry and single-crystal X-ray analysis (for the proligand 2 and its NiII derivative 3), together with computational methods (DFT and TD-DFT) was used to fully characterize and study the properties of all products. Both 2 and 3 crystallize in the orthorhombic non-centrosymmetric space group P212121, with two (R,R)-(−)-chiral carbon atoms in their structure. Second-order nonlinear polarizabilities β have been measured by using Harmonic Light Scattering at 1.91 μm, with the Pd(II) species showing the higher NLO response of 460 x 10-30 esu.

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