Diquat Derivatives: Highly Active, Two-Dimensional Nonlinear Optical Chromophores with Potential Redox Switchability

In this article, we present a detailed study of structure−activity relationships in diquaternized 2,2′-bipyridyl (diquat) derivatives. Sixteen new chromophores have been synthesized, with variations in the amino electron donor substituents, π-conjugated bridge, and alkyl diquaternizing unit. Our aim is to combine very large, two-dimensional (2D) quadratic nonlinear optical (NLO) responses with reversible redox chemistry. The chromophores have been characterized as their PF_6^− salts by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. Their visible absorption spectra are dominated by intense π → π^* intramolecular charge-transfer (ICT) bands, and all show two reversible diquat-based reductions. First hyperpolarizabilities β have been measured by using hyper-Rayleigh scattering with an 800 nm laser, and Stark spectroscopy of the ICT bands affords estimated static first hyperpolarizabilities β_0. The directly and indirectly derived β values are large and increase with the extent of π-conjugation and electron donor strength. Extending the quaternizing alkyl linkage always increases the ICT energy and decreases the E_(1/2) values for diquat reduction, but a compensating increase in the ICT intensity prevents significant decreases in Stark-based β_0 responses. Nine single-crystal X-ray structures have also been obtained. Time-dependent density functional theory clarifies the molecular electronic/optical properties, and finite field calculations agree with polarized HRS data in that the NLO responses of the disubstituted species are dominated by ‘off-diagonal’ β_(zyy) components. The most significant findings of these studies are: (i) β_0 values as much as 6 times that of the chromophore in the technologically important material (E)-4′-(dimethylamino)-N-methyl-4-stilbazolium tosylate; (ii) reversible electrochemistry that offers potential for redox-switching of optical properties over multiple states; (iii) strongly 2D NLO responses that may be exploited for novel practical applications; (iv) a new polar material, suitable for bulk NLO behavior

Modifizierte Dysenterie-Teilsanierung in einem Kernzuchtschweinebetrieb

In einem Brachyspira (B.) hyodysenteriae positiven Schweizer Kernzuchtbetrieb mit 170 Muttersauen und 600 Jungsauenaufzucht-/Mastplätzen wurde 2011 eine rollende Dysenteriesanierung über die Dauer von 12 Wochen durchgeführt. Neben einer vierwöchigen oralen Medikation (8.1 mg Tiamulin pro kg Körpergewicht) der auf dem Betrieb verbleibenden Schweine wurden sämtliche Stallungen gründlich gereinigt sowie die Restgülle mit Alzogur® (3 l/m3) und die Stalloberflächen mit Venno Vet 1 Super® (1.5 %) behandelt. Gleichzeitig wurde die Schadnager- und Fliegenbekämpfung intensiviert. Nach der Sanierung wurde der Betrieb während 6 Monaten mittels Untersuchung von Kottupfern von Durchfalltieren überwacht. In sämtlichen Kotproben konnten nach der Sanierung keine B. hyodysenteriae nachgewiesen werden. Die Sanierungskosten beliefen sich auf etwa CHF 104'500.–. Die Sanierung führte zu signifikant höheren Lebendtageszunahmen (+ 23.8 g, ± 10.1 g, P < 0.0001). Diese Leistungsverbesserung erbrachte einen jährlichen Mehrgewinn von CHF 18'500.–. On a Swiss nucleus sow breeding farm with 170 sows and 600 gilts/fatteners, an eradication of swine dysentery as modified partial depopulation was conducted in stages over a period of 12 weeks in 2011 after Brachyspira (B.) hyodysenteriae was detected in the herd. In addition to administering oral medication (8.1 mg tiamulin per kg body weight) for 4 weeks to the pigs remaining on the farm, all stables were cleaned thoroughly and the residual slurry was disinfected with Alzogur® (3 l/m3) while the surfaces were disinfected with Venno Vet 1 Super® (1.5 %). At the same time rodent and fly control was intensified. Upon completion of the eradication programme, the farm was monitored for 6 months by carrying out fecal swab analyses of pigs with diarrhea. All fecal samples were negative for B. hyodysenteriae. The costs of the eradication amounted to approximately CHF 104'500. The eradication yielded significantly higher live daily weight gain (+ 23.8 g, ± 10.1 g, P < 0.0001). This improved performance resulted in an additional economic benefit of CHF 18,500 per year