Syntheses, emission properties and intramolecular ligand exchange of zinc complexes with ligands belonging to the tmpa family

Beitat, Alexander; Foxon, Simon P.; Brombach, Christoph-Cornelius; Hausmann, Heike; Heinemann, Frank W.; Hampel, Frank; Monkowius, Uwe; Hirtenlehner, Christa; Knör, Günther; Schindler, Siegfried

doi:10.1039/c0dt01339k

Cited by 26 publications

(9 citation statements)

References 38 publications

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“…As expected, the cobalt(II) complex (L 6 )CoCl 2 12 is paramagnetic, displaying broad signals in its 1 H and 31 P NMR spectra. 25 The 1 H NMR spectrum displays ten resonances over the fourteen expected for a C S symmetrical complex (Fig. 11).…”

Section: Paramagnetic Nmr Spectroscopy Of the Cobalt Complexesmentioning

confidence: 99%

Zinc and cobalt complexes based on tripodal ligands: synthesis, structure and reactivity toward lactide

et al. 2014

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The coordination chemistry of a series of pro-ligands ([L¹]-[L⁶]) with cobalt and zinc derivatives has been studied. All complexes have been characterized by multinuclear NMR, elemental analysis, and by single-crystal X-ray diffraction studies. Polymerization of rac-lactide takes place at 130 °C in the presence of cobalt and zinc complexes to yield polymers under solvent free conditions with controlled molecular masses and narrow polydispersities.

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Section: Paramagnetic Nmr Spectroscopy Of the Cobalt Complexesmentioning

confidence: 99%

Zinc and cobalt complexes based on tripodal ligands: synthesis, structure and reactivity toward lactide

et al. 2014

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“…Both spectra display a broad absorption band with a maximum at approximately 270 nm (ε = 6150 m -1 cm -1 for EuL1; ε = 14100 m -1 cm -1 for EuL2), which is typical of πǞπ* transitions centred on the pyridyl unit. [25] Addition of Zn 2+ causes important variations in the absorption spectra of both complexes. In particular, metalion addition provokes a shift of the absorption maxima toward shorter wavelengths (ca.…”

Section: Absorption and Emission Electronic Spectroscopymentioning

confidence: 99%

Lanthanide Complexes with Heteroditopic Ligands as Fluorescent Zinc Sensors

et al. 2014

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International audienceWe report the synthesis of two ligands containing a DO3A unit (H3DO3A = 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid) linked to a triazacyclononane (TACN) moiety by a 2,6-dimethylpyridine spacer designed to form stable Ln3+ complexes in solution that respond to the presence of Zn2+ ions. The Eu3+ and Gd3+ complexes have been characterized by using a combination of experimental and theoretical techniques that include absorption and emission electronic spectroscopy, NMR spectroscopy, 1H relaxometry, and DFT calculations. The Ln3+ ions are eight-coordinated by the ligand, which binds to the metal ion through the seven donor atoms of the DO3A unit and the nitrogen atom of the pyridyl linker. Luminescence lifetime measurements recorded from solutions of the Eu3+ complexes in H2O and D2O and relaxometric measurements point to the absence of inner-sphere water molecules. The addition of Zn2+ causes important changes in the absorption spectra of the complexes that evidence the formation of both 1:1 and 2:1 (Ln3+/Zn2+) complex species. However, the emission lifetimes of the Eu3+ complexes and relaxivity experience weak changes, thus indicating that Zn2+ addition does not significantly affect the number of coordinated water molecules. The Gd3+ complexes show a weak emission band at 325 nm, the intensity of which dramatically increases in the presence of Zn2+. However, the “turn-on” behaviour induced by Zn2+ is not observed for other metal cations such as Ca2+, Mg2+ or Cu2+. DFT calculations indicate that a photoinduced electron-transfer (PET) process is responsible for the quenching of the luminescence in the absence of Zn2+

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“…Focusing on the latter, numerous previous works described the significant luminescence behavior of [M(L)X 2 ] (M = Zn, Cd; X = halide) or [Zn(L) n ] 2+ compounds, where L indicates a nitrogen bidentate ligand . Limited examples have been published with N , O ‐ligands, the most relevant being zinc(II) 8‐hydroxyquinolinate complexes (Znq 2 ), which showed highly controllable luminescence properties tuned by substituents on ligand, and high performances in electroluminescent devices .…”

Section: Introductionmentioning

confidence: 99%

Tuning the Fluorescence Emission and HOMO‐LUMO Band Gap in Homoleptic Zinc(II) Complexes with N,O‐Bidentate (Imidazo[1,5‐a]pyrid‐3‐yl)phenols

et al. 2019

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A series of homoleptic zinc(II) complexes of the general formula [Zn(LR)2] (HLR: (imidazo[1,5‐a]pyrid‐3‐yl)phenol; R: para‐substituent to the phenol) have been synthesized. The single‐crystal X‐ray structure analysis of complex [Zn(LH)2] (1) confirmed the expected N,O‐bidentate coordination of LR, via the pyridine‐like nitrogen of the imidazo[1,5‐a]pyridine skeleton and the phenolate oxygen. The photophysical properties of the complexes have been investigated in dichloromethane solution, showing fluorescence emission when excited with UV light (λexc = 340–360 nm). The intensity and λmax of the emission are both significantly influenced by the R‐substituent, the emission maxima moving from blue (R = CF3, Zn(LCF3)2] (6)) to orange (R = NO2, Zn(LNO2)2] (7). Most of [Zn(LR)2] compounds are characterized by moderate‐to‐good absolute photoluminescence quantum yields, with a maximum of 0.33 for [Zn(LH)2] (1). Density functional calculations allowed to identify the Natural Transition Orbitals involved in the electronic transitions and define the main transition as being HOMO‐LUMO (>95 %) in character. A good linear correlation was found between the HOMO energy and the Hammett σp constants associated to the R‐substituent, whereas the fluorescence behavior has been described in terms of HOMO‐LUMO band gap.

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Syntheses, emission properties and intramolecular ligand exchange of zinc complexes with ligands belonging to the tmpa family

Cited by 26 publications

References 38 publications

Zinc and cobalt complexes based on tripodal ligands: synthesis, structure and reactivity toward lactide

Zinc and cobalt complexes based on tripodal ligands: synthesis, structure and reactivity toward lactide

Lanthanide Complexes with Heteroditopic Ligands as Fluorescent Zinc Sensors

Tuning the Fluorescence Emission and HOMO‐LUMO Band Gap in Homoleptic Zinc(II) Complexes with N,O‐Bidentate (Imidazo[1,5‐a]pyrid‐3‐yl)phenols

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