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

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.     

How Do Redox Groups Behave around a Rigid Molecular Platform? Hexa(ferrocenylethynyl)benzenes and Their “Electrostatic” Redox Chemistry

A new family of hexakis(ferrocenylethynyl)benzenes was synthesized by Negishi coupling from ethynylferrocenes and C₆Br₆ and can be reversibly oxidized to stable hexaferrocenium salts (see picture, Ar^F=[3,5‐C₆H₃(CF₃)₂]). Their cyclic voltammograms show a single six‐electron wave, three distinct two‐electron waves, or a cascade of six single‐electron waves, depending on the electrolyte counterion and number of methyl substituents on the ferrocenyl groups.

     

Enhanced performance of thin-disk lasers by pumping into the zero-phonon line

Pumping Yb:YAG or Yb:LuAG into the zero-phonon line at 969?nm instead of using the common pump wavelength of 940?nm reduces the heat generation by 32%. In addition to the 3% increase of the Stokes efficiency, this significantly reduces the diffraction losses caused by the thermally induced phase distortions leading to a remarkable increase of the overall efficiency especially of fundamental-mode thin-disk lasers. Using this pumping scheme in an Yb:LuAG thin-disk laser, we achieved 742?W of nearly diffraction limited (M²≈1.5) output power at an unprecedented high optical efficiency of 58.5%. For multimode operation (M²≈15) the maximum optical efficiency of an Yb:YAG thin-disk laser was increased to 72%.     

Synthesis of 2,3-dihydro-1,3,4-thiadiazole,thiazole, and triazolo[4,3-a]pyrimidine derivatives from ethyl benzoylacetate

Thiophene and thiazole derivatives can be obtained from potassium salt of ethyl 3-oxo-3-phenyl-2-[(phenylamino)thioxomethyl]propanoate and ethyl chloroacetate in N,N-dimethylformamide solution under different conditions. 2,3-Dihydro-1,3,4-thiadiazoles and triazolo[4,3-a]pyrimidine were obtained from reaction of hydrazonoyl halides with each of thioanilide and pyrimidine-2-thione, respectively. Structures of the newly synthesized compounds were elucidated on the basis of elemental analysis, spectral data, and alternative synthesis route whenever possible. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:107–113, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10222     

Organophosphorus chemistry 23 [1], the reaction of α,β-unsaturated nitriles with alkyl phosphites and phosphorus ylides

Wittig reagents 2 react with furfurylidenemalonitrile ( 1a ) and thienylidenemalonitrile ( 1b ) to give a mixture of products ( 6 and 7 ). Compound 1b reacts with di-alkyl phosphites ( 3 ) and trialkyl phosphites ( 4 ) to give the phosphonate 1:1 adducts 9 and 12 , respectively. Structures of the new products were confirmed on the basis of elemental analyses and spectral studies.