Synthesis, structural studies, theoretical calculations, and linear and nonlinear optical properties of terpyridyl lanthanide complexes: new evidence for the contribution of f electrons to the NLO activity.
ABSTRACT The synthesis and structural, photophysical, and second-order nonlinear optical (NLO) properties of a novel lanthanide terpyridyl-like complex family LLn(NO(3))(3) (Ln = La, Gd, Dy, Yb, and Y) are reported. The isostructural character of this series in solution and in the solid state has been established on the basis of X-ray diffraction analysis in the cases of yttrium and gadolinium complexes, theoretical optimization of geometry (DFT), and NMR spectroscopy. The absorption, emission, and solvatochromic properties of the free terpyridyl-like ligand L were thoroughly investigated, and the twist intramolecular charge transfer (TICT) character of the lowest energy transition was confirmed by theoretical calculation (TDDFT and CIS). The similar ionochromic effect of the different lanthanide ions was evidenced by the similar UV-visible spectra of the complete family of complexes. On the other hand, the quadratic hyperpolarizability coefficient beta, measured by the harmonic light scattering (HLS) technique, is clearly dependent on the nature of the metal, and a careful examination of the particular case of yttrium unambiguously confirms the contribution of metal f electrons to the NLO activity.
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ABSTRACT: With the help of associations between Eu3+, Yb3+, and Nd3+ ions and low-potential redox-active ruthenium carbon-rich complexes bearing bipyridine chelating unit(s) of the type trans-[Ph–C≡C–(dppe)2Ru–C≡C–bipy-κ2N,N′–Ln(TTA)3], trans-[(dppe)2Ru(−C≡C–bipy-κ2N,N′–Ln(TTA)3)2], and trans-[Ph–C≡C–(dppe)2Ru–C≡C–C6H4–C≡C–bipy-κ2N,N′–Yb(TTA)3], we built new original d–f heterometallic complexes. Efficient sensitization in the visible range of the Nd3+ and Yb3+ near-infrared (NIR) emitters was achieved with the metal–acetylide antenna, while sensitization of the Eu3+ ion was not efficient owing to the low energy level of the antenna excited state. The redox properties of these groups also allow for low-potential redox modulation of NIR luminescence of the Yb3+ ion and, for the first time, of the Nd3+ ion.Organometallics 04/2014; 33(18):1824. · 4.25 Impact Factor
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ABSTRACT: A facile palladium-catalyzed synthesis of acridines has been realized by consecutive C=C double bond formation and C–N cross-coupling. A variety of functionalized acridines can be accessed from easily available o-dihalobenzenes and N-tosylhydrazones in a single operation. This one-pot protocol has a wide scope with respect to both coupling partners, and provides an efficient route to functionalized acridine derivatives, which are generally difficult to synthesize by previously known methods.European Journal of Organic Chemistry 10/2012; · 3.15 Impact Factor
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ABSTRACT: The electronic structure of Yb(Cp′)2(N–N) complexes with Cp′ = η5-C5R5 (Cp*) or η5-C9H7 (Ind) and N–N = DAB (N,N′-tert-butyl-1,4-diazabutadiene), bpy (2,2′-bipyridine), and pyca ((E)-N-(pyridine-2-ylmethylene)aniline) was investigated by means of DFT and ab initio (CASSCF/CASPT2) calculations. Whereas the agreement between experimental features and theory is fair for the Yb(Ind)2bpy molecule, the description of the electronic ground state of Yb(Ind)2DAB and of the Cp* complexes is more problematic. The relative energies of the closed-shell singlet, lowest open-shell singlet, and triplet were calculated for Yb(Ind)2DAB with various functionals at the DFT level, which overstabilize the closed-shell singlet. All functionals place the open-shell singlet energetically close to the triplet state. The best functionals (B3LYP, M06, TPSSh) estimate the singlet–triplet energy gap in the range 17–28 kJ·mol–1, in disagreement with the experimental data. The electronic structure of the smaller and more symmetric system Yb(η5-C5H5)2(N–N) (N–N = DAB, bpy), for which DFT fails at describing the ground state, has been investigated by CASSCF/CASPT2 calculations. The lowest energy electronic ground state corresponds to a (4f(Yb))2(π*DAB)0-(4f(Yb))0(π*DAB)2 (1A1) state, nearly degenerate to the triplet 4f(Yb)1(π*DAB)1 configuration according to a diradical picture.Organometallics 06/2012; 31(13):4693–4700. · 4.25 Impact Factor