Synthesis, Structures, and Optical Properties of Ruthenium(II) Complexes of the Tris(1-pyrazolyl)methane Ligand

Abstract

Four new complex salts [Ru II Cl(Tpm)(L A ) 2 ]-[PF 6 ] n [Tpm = tris(1-pyrazolyl)methane; n = 1, L A = pyridine (py) 1 or ethyl isonicotinate (EIN) 2; n = 3, L A = N-methyl-4,4′-bipyridinium (MeQ + ) 3 or N-phenyl-4,4′-bipyridinium (PhQ + ) 4] have been prepared and characterized. Electronic absorption spectra show intense d → π* metal-to-ligand charge-transfer (MLCT) absorption bands, while cyclic voltammetry reveals a reversible Ru III/II wave, accompanied by quasireversible or irreversible L A -based reductions for all except 1. Single crystal X-ray structures have been obtained for 1•Me 2 CO, 2, and 3•Me 2 CO. For 2−4, molecular first hyperpolarizabilities β have been measured in acetonitrile solutions via the hyper-Rayleigh scattering (HRS) technique at 800 nm. Stark (electroabsorption) spectroscopic studies on the MLCT bands in frozen butyronitrile allow the indirect estimation of static first hyperpolarizabilities β 0 . The various physical data obtained for 3 and 4 are compared with those reported previously for related cis-{Ru II (NH 3 ) 4 } 2+ species [Coe, B. J. et al. J. Am. Chem. Soc. 2005, 127, 4845]. TD-DFT calculations on the complexes in 1−4 confirm that their lowest energy absorption bands are primarily Ru II → L A MLCT in character, while Ru II → Tpm MLCT transitions are predicted at higher energies. DFT agrees with the Stark, but not the HRS measurements, in showing that β 0 increases with the electron-accepting strength of L A . The 2D nature of the chromophores is evidenced by dominant β xxy tensor components.

Nonlinear Optical Chromophores with Two Ferrocenyl, Octamethylferrocenyl, or 4-(Diphenylamino)phenyl Groups Attached to Rhenium(I) or Zinc(II) Centers

“…In each case, β tot increases sequentially on moving from gas phase to DCM to MeCN. Similarly, large solvent-induced enhancements of NLO responses are also predicted by DFT calculations on essentially V-shaped complexes with {Ru II Cl­(Tpm)} + (Tpm = tris­(1-pyrazolyl)­methane) electron-donating centers . In either medium, on moving along the Zn II Cl 2 series 1 → 3 , β tot increases, with a larger relative change when Me 8 Fc is replaced with −C 6 H 4 -4-NPh 2 groups.…”

Helquat Dyes: Helicene-like Push–Pull Systems with Large Second-Order Nonlinear Optical Responses

“…As noted previously for purely organic and ruthenium-based , chromophores, β tot increases substantially upon moving from the gas phase to MeCN solution. β tot is also larger for [5]­helquat 1 ′ than for [6]­helquat 6 ′ or for DAS + , differences that are reflected only partially in the experimental data (Table ).…”

A new strategy for simultaneously enhancing nonlinear optical response and electron stability in novel cup–saucer+–cage−-shaped sandwich electride molecules with an excess electron protected inside the cage

“…The coulomb-attenuated hybrid exchange-correlation density functional (CAM-B3LYP) has recently been developed for longrange interaction and charge transfer excitation systems. 24,25 CAM-B3LYP has been evaluated in organic push-pull electron systems, [26][27][28][29][30] organic metal, [31][32][33] and nanotubes. [34][35][36] Specially, CAM-B3LYP has successfully been applied to calculate molecular geometries and β 0 for many electride molecule systems.…”