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Title: Spectroscopic and photophysical properties of complexes of 4{prime}-ferrocenyl-2,2{prime}:6{prime},2{double_prime}-terpyridine and related ligands

Abstract

4{prime}-(Ferrocenyl)-2,2{prime}:6{prime}2{double_prime}-terpyridine (Fctpy) and 4{prime}-(4-pyridyl)-2,2{prime}:6{prime},2{double_prime}-terpyridine (pytpy) were prepared from the corresponding ferrocene- and pyridinecarboxaldehyle and 2-acetylpyridine using the Krohnke synthetic methodology. Metal complexes, [M(Fctpy){sub 2}](PF{sub 6}){sub 2} (M = Ru, Fe, Zn), [Ru(tpy)(Fctpy)](PF{sub 6}){sub 2} (tpy = 2,2{prime}:6{prime},6{double_prime}-terpyridine), and [Ru(pytpy){sub 2}](PF{sub 6}){sub 2} were prepared and characterized. Cyclic voltammetric analysis indicated Ru(III/II) and ferrocenium/ferrocene redox couples near expected potentials (Ru{sup III/II} {approximately}1.3 V and ferrocenium/ferrocene {approximately}0.6 V vs Ag/AgCl). In addition to dominant {pi}{sub tpy} {r_arrow} {pi}{sub tpy}{sup *} UV absorptions near 240 and 280 nm and d{sub {pi}}{sup Ru} {r_arrow} {pi}{sub tpy}{sup *} MLCT absorptions around 480 nm, the complexes [Ru(Fctpy){sub 2}](PF{sub 6}){sub 2} and [Ru(tpy)(Fctpy)](PF{sub 6}){sub 2} exhibit an unusual absorption band around 530 nm. Resonance Raman measurements indicate that this band is due to a {sup 1}[(d({pi}){sub Fc}){sup 6}] {r_arrow} {sup 1}[(d({pi}){sub Fc}){sup 5}({pi}{sup *}{sub tpy}{sup Ru}){sup 1}] transition. For [Ru(Fctpy){sub 2}](PF{sub 6}){sub 2} and [Ru(tpy)(Fctpy)](PF{sub 6}){sub 2}, excited-state emission and lifetime measurements indicated an upper-limit emission quantum yield of 0.003 and an upper-limit emission lifetime of 0.025 {micro}s. The influence of the ferrocenyl site on excited-state decay is discussed, and an excited-state energy level diagram is proposed.

Authors:
; ; ;  [1]; ;  [2];  [3]
  1. Univ. of North Carolina, Greensboro, NC (United States). Dept. of Chemistry
  2. Wayne state Univ., Detroit, MI (United States). Dept. of Chemistry
  3. Los Alamos National Labs., Los Alamos, NM (United States)
Publication Date:
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
354364
Resource Type:
Journal Article
Resource Relation:
Journal Name: Inorganic Chemistry; Journal Volume: 38; Journal Issue: 10; Other Information: PBD: 17 May 1999
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; PYRIDINES; RUTHENIUM COMPLEXES; IRON COMPLEXES; ZINC COMPLEXES; REDOX POTENTIAL; ENERGY-LEVEL TRANSITIONS; QUANTUM EFFICIENCY; LIFETIME

Citation Formats

Hutchinson, K., Morris, J.C., Nile, T.A., Walsh, J.L., Thompson, D.W., Petersen, J.D., and Schoonover, J.R. Spectroscopic and photophysical properties of complexes of 4{prime}-ferrocenyl-2,2{prime}:6{prime},2{double_prime}-terpyridine and related ligands. United States: N. p., 1999. Web. doi:10.1021/ic980798b.
Hutchinson, K., Morris, J.C., Nile, T.A., Walsh, J.L., Thompson, D.W., Petersen, J.D., & Schoonover, J.R. Spectroscopic and photophysical properties of complexes of 4{prime}-ferrocenyl-2,2{prime}:6{prime},2{double_prime}-terpyridine and related ligands. United States. doi:10.1021/ic980798b.
Hutchinson, K., Morris, J.C., Nile, T.A., Walsh, J.L., Thompson, D.W., Petersen, J.D., and Schoonover, J.R. Mon . "Spectroscopic and photophysical properties of complexes of 4{prime}-ferrocenyl-2,2{prime}:6{prime},2{double_prime}-terpyridine and related ligands". United States. doi:10.1021/ic980798b.
@article{osti_354364,
title = {Spectroscopic and photophysical properties of complexes of 4{prime}-ferrocenyl-2,2{prime}:6{prime},2{double_prime}-terpyridine and related ligands},
author = {Hutchinson, K. and Morris, J.C. and Nile, T.A. and Walsh, J.L. and Thompson, D.W. and Petersen, J.D. and Schoonover, J.R.},
abstractNote = {4{prime}-(Ferrocenyl)-2,2{prime}:6{prime}2{double_prime}-terpyridine (Fctpy) and 4{prime}-(4-pyridyl)-2,2{prime}:6{prime},2{double_prime}-terpyridine (pytpy) were prepared from the corresponding ferrocene- and pyridinecarboxaldehyle and 2-acetylpyridine using the Krohnke synthetic methodology. Metal complexes, [M(Fctpy){sub 2}](PF{sub 6}){sub 2} (M = Ru, Fe, Zn), [Ru(tpy)(Fctpy)](PF{sub 6}){sub 2} (tpy = 2,2{prime}:6{prime},6{double_prime}-terpyridine), and [Ru(pytpy){sub 2}](PF{sub 6}){sub 2} were prepared and characterized. Cyclic voltammetric analysis indicated Ru(III/II) and ferrocenium/ferrocene redox couples near expected potentials (Ru{sup III/II} {approximately}1.3 V and ferrocenium/ferrocene {approximately}0.6 V vs Ag/AgCl). In addition to dominant {pi}{sub tpy} {r_arrow} {pi}{sub tpy}{sup *} UV absorptions near 240 and 280 nm and d{sub {pi}}{sup Ru} {r_arrow} {pi}{sub tpy}{sup *} MLCT absorptions around 480 nm, the complexes [Ru(Fctpy){sub 2}](PF{sub 6}){sub 2} and [Ru(tpy)(Fctpy)](PF{sub 6}){sub 2} exhibit an unusual absorption band around 530 nm. Resonance Raman measurements indicate that this band is due to a {sup 1}[(d({pi}){sub Fc}){sup 6}] {r_arrow} {sup 1}[(d({pi}){sub Fc}){sup 5}({pi}{sup *}{sub tpy}{sup Ru}){sup 1}] transition. For [Ru(Fctpy){sub 2}](PF{sub 6}){sub 2} and [Ru(tpy)(Fctpy)](PF{sub 6}){sub 2}, excited-state emission and lifetime measurements indicated an upper-limit emission quantum yield of 0.003 and an upper-limit emission lifetime of 0.025 {micro}s. The influence of the ferrocenyl site on excited-state decay is discussed, and an excited-state energy level diagram is proposed.},
doi = {10.1021/ic980798b},
journal = {Inorganic Chemistry},
number = 10,
volume = 38,
place = {United States},
year = {Mon May 17 00:00:00 EDT 1999},
month = {Mon May 17 00:00:00 EDT 1999}
}
  • A series of [Ru(tpy)(X)(Y)(Z)]{sup n+} complexes have been synthesized (tpy = 2,2{prime},2{double_prime}-terpyridine: X = triphenylphosphine (PPh{sub 3}); trans Y = Z = trifluoroacetate (CF{sub 3}CO{sub 2}{sup {minus}}), n = 0(1); trans Y=Z=4-ethylpyridine (4-Etpy), n = 2 (2); trans Y = Z = 4(dimethylamino)pyridine (DMAP), n = 2 (3); Y = 4-Etpy, Z = chloride (Cl{sup {minus}}), n = 1 (4); cis Y = Z = 4-Etpy, n = 2(5); X = Cl{sup {minus}}; trans Y = Z = 4-Etpy, n = 1 (6); X = Y = Z = 4-Etpy, n = 2 (7)) and isolated as their PF{sub 6}{supmore » {minus}} salts. UV-visible spectroscopic and electrochemical studies have been conducted and photochemical and photophysical properties of representative examples determined. Emission, absorption, and electrochemical properties depend on the nonchromophoric ligands and the coordination geometry. The complexes investigated emit in 4:1 (v/v) EtOH/MeOH glasses at 77 K and have lifetimes which range from 1.1 to 11.0 {mu}s depending on the ancillary ligands. Through a combination of emission spectral fitting and resonance Raman measurements on [Ru(tpy){sub 2}](PF{sub 6}){sub 2}, the acceptor characteristics of tpy as a chromophoric ligand have been analyzed. At room temperature the Ru(II) mono-tpy complexes are short-lived, weak emitters. Emission quantum yields and lifetimes for [Ru(tpy)(4-Etpy){sub 3}](PF{sub 6}){sub 2}(7) and [Ru(tpy){sub 2}](PF{sub 6}){sub 2} in 4:1 (v/v) EtOH/MeOH are strongly temperature dependent from T=90-270 K. These results are consistent with the existence of low-lying dd states which are responsible for the short excited state lifetimes at room temperature and the appearance of ligand-loss photochemistry for 7.« less
  • Lanthanum nitrate 2,2{prime}:6{prime},2{double_prime}-terpyridine (terpy) complexes formed by the reaction of La(NO{sub 3}){center_dot}6H{sub 2}O with terpy were characterized by NMR and X-ray crystallography. Seven unique species were observed by NMR, all of which retained none of the waters of solvation.
  • Technetium(II) complexes of the general formula cis(X),trans(P)-(TcX{sub 2}(PR{sub 2}R{prime}){sub 2}L), where X = Cl or Br, PR{sub 2}R{prime} = dimethylphenylphosphine or ethyldiphenylphosphine, and L = 2,2{prime}-bipyridine (bpy) or 1,10-phenanthroline (phen), have been synthesized and characterized. They are prepared by replacement of one halide and one phosphine ligand of mer-TcX{sub 3}(PR{sub 2}R{prime}){sub 3} by the bidentate L ligand in refluxing ethanol, followed by reduction to the Tc(II) oxidation state and precipitation from solution by the addition of aqueous hydroxide. Additionally, related technetium(II) complexes of the general formula trans(P)-(TcX(PR{sub 2}R{prime}){sub 2}(terpy)){sup +}, where terpy = 2,2{prime}:6{prime},2{double prime}-terpyridine, have been synthesized and characterized.more » They are prepared by terpy substitution onto and displacement of one phosphine and two halide ligands from mer-TcX{sub 3}(PR{sub 2}R{prime}){sub 3} in refluxing ethanol with concomitant reduction of Tc(III) to Tc(II). Evidence suggests a two-step synthetic process wherein the terpy ligand first displaces one halide and one phosphine moiety to form a Tc(III) complex in which terpy functions as a bidentate ligand, followed by subsequent displacement of the second halide ligand with coordination of the third heterocyclic nitrogen of the terpy ligand and reduction to the Tc(II) state. All of the complexes have been characterized by elemental analyses of prototypes, by UV-visible spectrophotometry, and by fast atom bombardment mass spectrometry in the positive ion mode. 28 refs., 3 figs., 7 tabs.« less
  • Five supramolecular systems containing the Ru(ttp){sub 2}{sup 2+} photosensitizer (P) covalently linked to an electron acceptor (A), MV{sup 2+}, and/or an electron donor (D), PTZ or DPAA, have been synthesized; ttp is 4{prime}-p-tolyl-2,2{prime}:6{prime},2{double prime}-terpyridine, MV{sup 2+} is methyl viologen, PTZ is phenotiazine, and DPAA is di-p-anisylamine. In the D-P-A triads the electron donor and acceptor groups are linked in opposite positions with respect to the photosensitizer. The spectroscopic properties (room-temperature absorption spectra, emission spectra and lifetimes in the 90-200 K temperature range, and transient absorption spectra and lifetimes at 150 K) and the (room-temperature) electrochemical behavior of the supramolecular systemsmore » and of their components have been investigated. At 90 K, where the solvent is frozen, no quenching of the photosensitizer luminescence is observed for all the supramolecular systems. At 150 K, where the solvent is fluid, the results obtained were as follows. In the PTZ-Ru(ttp){sub 2}{sup 2+} dyad, neither quenching of the photosensitizer luminescence nor formation of oxidized donor are observed. In the DPAA-Ru(ttp){sub 2}{sup 2+} dyad, luminescence quenching and transient formation of the oxidized donor take place. For the Ru(ttp){sub 2}{sup 2+}-MV{sup 2+} dyad, transient formation of the reduced acceptor is observed, but the lifetime of the photosensitizer luminescence increases, indicating that charge recombination leads back to the excited photosensitizer. The PTZ-Ru(ttp){sub 2}{sup 2+}-MV{sup 2+} triad behaves as the Ru(ttp){sub 2}{sup 2+}-MV{sup 2+} dyad. For the DPAA-Ru(ttp){sub 2}{sup 2+}-MV{sup 2+} triad, strong luminescence quenching is observed, and transient absorption spectroscopy shows that charge separation is followed by a very fast charge recombination reaction ({tau}<100 ns). Thermodynamic and kinetic aspects of the photoinduced electron-transfer processes are discussed.« less
  • A series of transition metal and lanthanide complexes of 4 Prime -(4-carboxyphenyl)-2,2 Prime :6 Prime ,2 Double-Prime -terpyridine (HL, 1), namely [M(L){sub 2}]{center_dot}5H{sub 2}O (M=Ni, 2; Co, 3), [Zn(L){sub 2}]{sub n}{center_dot}0.5nH{sub 2}O (4) and [Ln(L){sub 3}]{sub n} (Ln=Nd, 5; Gd, 6; Er, 7) were hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Isomorphic compounds 2 and 3 are mononuclear molecules with two ligand chelating to the metal centers via tridentate terpyridyl, while compound 4 adopts 1D chain-like structure, in which five-coordinate zinc centers are surrounded by three ligands. Compounds 5-7 also display 1D chain-like structure, but the nine-coordinate lanthanidemore » centers bonded by four ligands. Luminescent property indicates that compound 4 exhibits photoluminescence in the solid state at room temperature. - Graphical abstract: Six complexes of 4 Prime -(4-carboxyphenyl)-2,2 Prime :6 Prime ,2 Double-Prime -terpyridine were synthesized via assembly with transition metal and lanthanide ions, respectively. Among them, [Ni(L){sub 2}]{center_dot}5H{sub 2}O and [Co(L){sub 2}]{center_dot}5H{sub 2}O are monomers, while [Zn(L){sub 2}]{sub n}{center_dot}0.5nH{sub 2}O and [Ln(L){sub 3}]{sub n} display chain-like structures. Highlights: Black-Right-Pointing-Pointer Compounds of 4 Prime -(4-carboxyphenyl)-2,2 Prime :6 Prime ,2 Double-Prime -terpyridine were synthesized. Black-Right-Pointing-Pointer [Ni(L){sub 2}]{center_dot}5H{sub 2}O and [Co(L){sub 2}]{center_dot}5H{sub 2}O are monomers. Black-Right-Pointing-Pointer [Zn(L){sub 2}]{sub n}{center_dot}0.5nH{sub 2}O and [Ln(L){sub 3}]{sub n} display chain-like structures.« less