Synthesis, Characterization, Photophysical, and Anion-Binding Studies of Luminescent Heteroleptic Bis-Tridentate Ruthenium(II) Complexes Based on 2,6-Bis(Benzimidazole-2-yl)Pyridine and 4′-Substituted 2,2′:6′,2′′ Terpyridine Derivatives

Abstract

A series of heteroleptic tridentate ruthenium(II) complexes of composition [(H(2)pbbzim)Ru(tpy-X)](PF(6))(2) (1-7), where H(2)pbbzim = 2,6-bis(benzimidazole-2-yl)pyridine and tpy-X = 4'-substituted terpyridine ligands with X = H, p-methyl phenyl (PhCH(3)), p-bromomethylphenyl (PhCH(2)Br), p-dibromomethylphenyl (PhCHBr(2)), p-cyanomethylphenyl (PhCH(2)CN), p-triphenylphosphonium methylphenyl bromide (PhCH(2)PPh(3)Br), and 4'-phenylformyl (PhCHO) groups, has been synthesized and characterized by using standard analytical and spectroscopic techniques. These compounds were designed to increase the excited-state lifetime of ruthenium(II) bisterpyridine-type complexes. The X-ray crystal structure of a representative compound 2, which crystallized with monoclinic space group P2(1)/c, has been determined. The absorption spectra, redox behavior, and luminescence properties of the ruthenium(II) complexes have been thoroughly investigated. All of the complexes display moderately strong luminescence at room temperature with lifetimes in the range of 10-58 ns. Correlations have been obtained for the Hammett sigma(p) parameter with their MLCT emission energies, lifetimes, redox potentials, proton NMR chemical shifts, etc. The anion binding properties of all the complexes as well as the parent ligand H(2)pbbzim have been studied in acetonitrile using absorption, emission, and (1)H NMR spectral studies, and it has been observed that the metalloreceptors act as sensors for F(-), AcO(-), and to some extent H(2)PO(4)(-). At a relatively lower concentration of anions, a 1:1 H-bonded adduct is formed; however, in the presence of an excess of anions, stepwise deprotonation of the two benzimidazole N-H fragments occurs, an event which is signaled by the development of vivid colors visible with the naked eye. The receptor-anion binding constants have been evaluated. Cyclic voltammetric (CV) measurements carried out in acetonitrile-dimethylformamide (9:1) provided evidence in favor of anion (F(-), AcO(-)) concentration dependent electrochemical responses, enabling 1 - 7 to act as suitable electrochemical sensors for F(-) and AcO(-) ions.

Anion Effects to Electrochromic Properties of Ru-based Metallo-supramolecular Polymers

“…[15] It is expected that the anion exchange causes the structural reorganization of the polymer, based on the different ionic interaction to the Ru(II) complex moiety. [16,17] The counter anions of the original polyRu are chloride ions, because RuCl 2 (DMSO) 4 , was used as the Ru(II) salt. The maximum wavelength of the MLCT absorption in polyRu was almost the same to that in polyRu-Cl, which was obtained by the treatment of polyRu with LiCl.…”

DSSC'ler için NNN ligantlar ile kararlaştırılmış Rutenyum malzemeler

“…Bu komplekslerin optik ve redoks özellikleri, kendilerine güneş enerjisi dönüşüm proseslerinde büyük ilgi kazandırmıştır [6]. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. 2012 yılında NNN ve 4,4′ -dikarboksilik asit-2,2′ -bipiridin ligantları içeren üç adet rutenyum kompleksi sentezlendi ve boya duyarlı güneş hücrelerinde duyarlaştırıcı olarak kullanıldı [22].…”

Rational design of a material for rapid colorimetric Fe2+ detection

“…Various derivatives of 2,2′:6′,2″-terpyridine (terpy) have been developed and implemented as such sensing receptors as summarized in seminal works by Constable [4] and Hancock [5]. Terpy based molecules were utilized to identify various metal cations [5][6][7] and cation-anion pairs [8,9]. To adjust polarity and therefore solubility, as well as to enhance sensing characteristics, terpy motifs have been combined into a variety of organic, organometallic, and supramolecular architectures.…”