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(NO3)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 thourougly 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 β, 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

New [(D-terpyridine)-Ru-(D or A-terpyridine)][4-EtPhCO2](2) complexes (D = electron donor group; A = electron acceptor group) as active second-order non linear optical chromophores

The dipolar and octupolar contributions of the second order nonlinear optical properties of [(4\u2032-(C6H4-p-D)-2,2\u2032:6\u2032,2\u2032\u2032-terpyridine)-Ru-(4\u2032-(C6H4-p-A)-2,2\u2032:6\u2032,2\u2032\u2032-terpyridine)]Y2 heteroleptic complexes (D and A are donor and acceptor groups, respectively), and related free terpyridines and homoleptic complexes, have been obtained by means of a comprehensive combination of Electric Field Induced Second Harmonic generation, Third Harmonic Generation, and Harmonic Light Scattering measurements. These results evidence how a metal can act as a bridge between two \u3c0-delocalized terpyridine moieties bearing a D and an A group, respectively, leading to a large quadratic hyperpolarizability hugely dominated by the octupolar contributio

A Tight Bound on the Throughput of Queueing Networks with Blocking

In this paper, we present a bounding methodology that allows to compute a tight bound on the throughput of fork-join queueing networks with blocking and with general service time distributions. No exact models exist for queueing networks with general service time distributions and, consequently, bounds are the only certain information available. The methodology relies on two ideas. First, probability mass fitting (PMF) discretizes the service time distributions so that the evolution of the modified system can be modelled by a discrete Markov chain. Second, we show that the critical path can be computed with the discretized distributions and that the same sequence of jobs offers a bound on the original throughput. The tightness of the bound is shown on computational experiments (error on the order of one percent). Finally, we discuss the extension to split-and-merge networks and the approximate estimations of the throughput