Alkynyl-Bridged Ruthenium(II) 4′-Diferrocenyl-2,2′:6′,2′′-terpyridine Electron Transfer Complexes: Synthesis, Structures, and Electrochemical and Spectroscopic Studies

Abstract

The novel ligand 4′-diferrocenylalkyne-2,2′:6′,2′′-terpyridine (7; Fc-CC-Fc-tpy; tpy = terpyridyl; Fc = ferrocenyl) and its Ru2+ complexes 8–10 have been synthesized and characterized by single-crystal X-ray diffraction, cyclic voltammetry, and UV–vis and luminescence spectroscopy. Electrochemical data and UV absorption and emission spectra indicate that the insertion of an ethynyl group causes delocalization of electrons in the extended π* orbitals. Cyclic voltammetric measurements of 7 show two successive reversible one-electron-oxidation processes with half-wave potentials of 0.53 and 0.78 V. The small variations of the E 1/2 values for the Fe2+/Fe3+ redox couples after the coordination of the Ru2+ ion suggest a weak interaction between the Ru2+ and Fe2+ centers. After insertion of an ethynyl group, UV–vis absorption spectra show a red shift of the absorption peak of the 1[(d(π)Fe)6] → 1[(d(π)Fe)5(π*tpy Ru)1] MMLCT of the Ru2+ complexes. The Ru2+ complex 8 exhibits the strongest luminescence intensity (λmax em 712 nm, Φem = 2.63 × 10–4, τ = 323 ns) relative to analogous ferrocene-based terpyridine Ru(II) complexes in H2O/CH3CN (4/1 v/v) solution.

Ferrocene‐Alkynyl Conjugated Molecular Wires: Synthesis, Characterization, and Conductance Properties

“…The ethynyl moiety is almost linear and exhibits an average angle of 177°. The C≡C triple bond length (about 1.19 Å) is close to those reported for analogous ferrocene‐acetylene substituted derivatives . The C−C single bond average length (about 1.433 Å) in the rod is shorter than the C−C single bond length (C12−C13, 1.486(4) Å) in the side chains, indicating that the π electron is highly delocalized along the rod.…”

A ruthenium(II) complex-based lysosome-targetable multisignal chemosensor for in vivo detection of hypochlorous acid

“…S8, the most intense peaks below 300 nm of Ru-Fc and its cracked product are dominated by the ligand-centered p / p * transition, while the absorption bands in the visible region are the MLCT bands of ruthenium(II) complexes. Since the ded absorption band of ferrocene (around 460 nm [62]) is close to the MLCT transition band of Ru(II) complexes, the absorption centered at 456 nm of Ru-Fc is stronger (ε ¼ 2.06 Â 10 4 cm À1 M À1 ) than that of [Ru(bpy) 2 (COOH-bpy)] 2þ (ε ¼ 1.60 Â 10 4 cm À1 M À1 ). Due to the presence of effective PET process in Ru-Fc, the luminescence of Ru-Fc is almost negligible with excitation at 456 nm.…”

“…As shown in Scheme 1, the new chemosensor, Ru-Fc, was designed according to the "PL and ECL reporter-reactive linkerquencher" sandwich approach [41]: a bipyridine-ruthenium(II) complex core was used as a PL and ECL reporter, a ferrocenyl moiety as signal quencher [62,63], and a hydrazine as the reactive linker. The choice of bipyridine-ruthenium(II) complex as a signal reporter is due to its rich PL and ECL properties reported in literature [12,27], and the choice of ferrocenyl moiety as a signal quencher is based on the consideration that ferrocenyl derivatives can effectively quench the luminescence through the PET process to corrupt the excited state of a luminophore [63].…”

Substituent and Solvent Effects on the Electrochemical Properties and Intervalence Transfer in Asymmetric Mixed‐Valent Complexes Consisting of Cyclometalated Ruthenium and Ferrocene

“…In addition to symmetric structures, [2,7] redox asymmetric systems have also been well studied, as demonstrated by the early works of the groups of Taube, [8] Henry, [9] Sato, [10] Meyer, [11] and Long, [12] as well as more recent works by Kaim, [13] Low, [14] Yuan, [15] Liu, [16] van Koten, [17] Veciana, [18] Winter, [19] and Zhong, [20] among others. [21] However, studies on the changes of E op by a combined method of structure modification and solvent variation are limited.…”