Synthesis, Crystal Structures, and Nonlinear Optical (NLO) Properties of New Schiff-Base Nickel(II) Complexes. Toward a New Type of Molecular Switch?

Abstract

An H2L Schiff-base ligand that was obtained from the monocondensation of diaminomaleonitrile and 4-(diethylamino)salicylaldehyde is reported together with four related nickel(II) complexes formulated as [Ni(L)(L')] (L' = MePhCHNH2, iPrNH2, Py, and PPh3). Crystal structures have been solved for H2L, [Ni(L)(MePhCHNH2)], and [Ni(L)(iPrNH2)]. Surprisingly, the complexation process leads to the formation of a rather unusual nickel amido (-NH-Ni(II)) bond by deprotonation of the primary amine of H2L. A reduction of the quadratic hyperpolarizability (beta) from 38 x 10(-30) to 17.5 x 10(-30) cm5 esu(-1) is evidenced on H2L upon metal complexation by the electric-field-induced second-harmonic (EFISH) technique. Qualitative ZINDO/SCI quantum chemical calculations indicate that, in [Ni(L)(MePhCHNH2)], the beta orientation strongly depends on the laser wavelength. In particular, a beta rotation strictly equal to 90 degrees could be obtained with 1.022 microm incident light on passing from [Ni(L)(MePhCHNH2] to a hypothetical [Ni(HL)(MePhCHNH2]+ protonated complex, thus raising the possibility for a new type of molecular switch.

Crystal structure of tetraaquabis(dimethylformamide)nickel(II) tetrachloroterephthalate, [Ni(H2O)4(C3H7NO)2](C8Cl4O4)

“…This is due to their intriguing structural features and tailor-made applications as functional materials for chemical catalysis [2], gas separation and storage [3], non-linear optic (NLO) [4], luminescence [5], and magnetism [6]. The asymmetric unit is composed of ac ationic moiety [Ni(DMF) 2 …”

Synthesis, Crystal Structure, and Second‐Order Nonlinear Optical Properties of Ruthenium(II) Complexes with Substituted Bipyridine and Phenylpyridine Ligands

“…However, this seems to be a general tendency frequently observed in the calculated spectra of inorganic chromophores. [26] The fact that the magnitude of this shift is especially pronounced in the case of the low-energy transition of [Ru(bpy) 2 6 ], which is assumed to arise from an intense metal-phenyl charge transfer, may be additionally related to an enhancement of the ruthenium-ligand distance within the DFT computation. Apart from these energy differences, a qualitative agreement between experiment and calculation is observed on two important points: (i) both complexes exhibit a very intense high-energy transition and a less intense one located at lower energy; (ii) while the high-energy transitions are grossly located at the same energy range in both derivatives, the low-lying transition is considerably red-shifted in the case of the cyclometalated compound.…”

Synthesis, structures and antimicrobial activities of nickel(II) and zinc(II) diaminomaleonitrile-based complexes

“…The geometry around the nickel atom is square planar, and the angle sum in the nickel plane is 360.1°. The bond distances between Ni(1) and O are 1.836(5) and 1.834(5) Å, and the Ni(1)-N bond lengths are 1.854(6) and 1.862(6) Å [27].…”