Synthesis, Linear, and Quadratic‐Nonlinear Optical Properties of Octupolar D₃ and D_2d Bipyridyl Metal Complexes

Abstract

A series of D3 (Fe(II), Ru(II), Zn(II), Hg(II)) and D2d (Cu(I), Ag(I), Zn(II)) octupolar metal complexes featuring different functionalized bipyridyl ligands has been synthesized, and their thermal, linear (absorption and emission), and nonlinear optical (NLO) properties were determined. Their quadratic NLO susceptibilities were determined by harmonic light scattering at 1.91 microm, and the molecular hyperpolarizability (beta0) values are in the range of 200-657 x 10(-30) esu for octahedral complexes and 70-157 x 10(-30) esu for tetrahedral complexes. The octahedral zinc(II) complex 1 e, which contains a 4,4'-oligophenylenevinylene-functionalized 2,2'-bipyridine, exhibits the highest quadratic hyperpolarizability ever reported for an octupolar derivative (lambdamax=482 nm, beta1.91(1 e)=870 x 10(-30) esu, beta0(1 e)=657 x 10(-30) esu). Herein, we demonstrate that the optical and nonlinear optical (NLO) properties are strongly influenced by the symmetry of the complexes, the nature of the ligands (donor endgroups and pi linkers), and the nature of the metallic centers. For example, the length of the pi-conjugated backbone, the Lewis acidity of the metal ion, and the increase of ligand-to-metal ratio result in a substantial enhancement of beta. The contribution of the metal-to-ligand (MLCT) transition to the molecular hyperpolarizability is also discussed with respect to octahedral d6 complexes (M=Fe, Ru).

Efficient Photoswitching of the Nonlinear Optical Properties of Dipolar Photochromic Zinc(II) Complexes

“…NMR spectra were recorded on Bruker DPX-200, AV 300 or AV 500 MHz spectrometers. 1 H and 13 C chemical shifts are given versus SiMe 4 and were determined by reference to residual 1 H and 13 C solvent signals. Assigments of carbon atoms were based on HMBC, HMQC and COSY experiments.…”

“…1 Compounds 5a,b 2 were prepared by a Suzuki coupling reaction between the appropriate arylboronic acid and 2,4-dibromo-5-methylthiophene 1 (Scheme S1). 4,4'-bis(diethylphosphonomethyl)-[2,2']-bipyridine 4 was synthesized using published procedure. Zinc acetate dihydrate was obtained from Acros Organics and used as received.…”

Synthesis and Photophysical Properties of Bis‐Cyclometallated Iridium(III)–Styryl Complexes and Their Saturated Analogues

“…The [a] λ em /nm [b] τ o /µs [b] [Ir(C ∧ N-ppy-4-CH=CHC 6 H 4 R) 2 ] 2 (µ-Cl) 2 (3a-3d) 2+ complexes. [20] Moderately intense bands are present in the lower energy region (450-550 nm). The absorption bands of 3c at 467 nm and 3d at 500 nm are tentatively assigned to an admixture of 1 MLCT/ 3 MLCT transitions.…”

Optically Tunable Nonlinearities in Polymers Based on Photoisomerizable Metal-Based Coordination Complexes

“…This result is in marked contrast with similar octupolar complexes [Zn(1) 3 ] 2+ (dk = 65 nm) or [Zn(4a) 3 ] 2+ (dk = 62 nm). [57] This small red-shift can be understood by the electron-withdrawing character of the azo moieties, which can affect the charge transfer along the whole p-conjugated backbone. The NLO measurements were performed in concentrated dichloromethane solution by harmonic light scattering (HLS), using k = 1.91 lm as the fundamental wavelength.…”

“…Complex 6a displays a very large hyperpolarizability (b 0 = 590 × 10 -30 esu), similar to that of [Zn(4a) 3 ][TRISPHAT] 2 (b 0 = 657 × 10 -30 esu), which features a bistyryl conjugated backbone. [57] Poly(methyl methacrylate) (PMMA) and polycarbonate (PC) matrices were doped with 6a and 7 by co-dissolving the complexes in 1,1,2-trichloroethane. The resulting solutions were subsequently spin-coated onto glass slides.…”