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We show that the organic salt 4-N,N-dimethylamino-4Ј-NЈ-methyl-stilbazolium tosylate, originally developed for electro-optic applications, is also a very interesting material for phase-matched parametric interactions such as frequency-doubling and optic parametric oscillation in the near infrared. These favorable properties are due to the large off-diagonal element d 26 which gives measured effective phase-matchable nonlinear optical coefficients of d eff ϭ31Ϯ5 and 15Ϯ3 pm/V at the telecommunication wavelengths of ϭ1313 and 1535 nm, respectively.

Relaxation processes in nonlinear optical modified polyimide polymers with side-chain azo chromophores having glass transition temperatures in the range of 140 < T g < 170 °C have been studied. The relaxational mechanisms of the side-chain chromophores in these polymers have been investigated above and below the glass transition by second-harmonic decay, dielectric relaxation, and differential scanning calorimetry measurements. The nonexponential relaxation in both the time and frequency domains was modeled by the Kohlrausch−Williams−Watts (KWW) function. The nonlinear relaxational behavior of these polymers can be modeled in terms of the Tool−Narayanaswamy description of glassy state behavior. It allows for the nonlinear extension of the liquid equilibrium state behavior into and below the glass transition region with an accurate prediction of the relaxation times over more than 15 orders of magnitude in time. Time−temperature scaling of the relaxation times with (T g − T)/T as the relevant scaling parameter is observed below the glass transition.

3 ](ClO 4 ) 2 (3), the 17 O exchange between the bulk water and the carbonyl oxygens have been studied by 17 O NMR spectroscopy, and the X-ray crystallographic structures of 1 and 2 have been determined. The water exchange of equatorially and axially coordinated water molecules on 1 and 2 follow an I d mechanism and are characterized by k eq 298 (s -1 ), ∆H q (kJ/mol), and ∆S q (J/(mol K)) of (2.54 ( 0.05) × 10 -6 , 111.6 ( 0.4, and 22.4 ( 1 (1-eq); (3.54 ( 0.02) × 10 -2 and 81 (1-ax); (1.58 ( 0.14) × 10 -7 , 120.3 ( 2, and 28.4 ( 4 (2-eq); and (4.53 ( 0.08) × 10 -4 , 97.9 ( 1, and 19.3 ( 3 (2-ax). The observed reactivities correlate with the strength of the Ru-OH 2 bonds, as expressed by their length obtained by X-ray studies: 2.079 (1-eq), 2.140 (1-ax), 2.073 (2-eq), and 2.110 (2-ax) Å. 3 is strongly acidic with a pK a of -0.14 at 262 K. Therefore, the acid-dependent water exchange can take place through 3 or Ru(CO) 3 (H 2 O) 3 OH + with an estimated k eq 298 of 10 -4 /10 -3 s -1 and k OH 262 of 0.053 ( 0.006 s -1 . The 17 O exchange rate between the bulk water and the carbonyl oxygens increases from 1 to 2 to 3. For 1 an upper limit of 10 -8 s -1 was estimated. For 2, no acid dependence of k Ru CO between 0.1 and 1 m Htos was observed. At 312.6 K, in 0.1 and 1 m Htos, k Ru CO ) (1.18 ( 0.03) × 10 -4 . For the tricarbonyl complex, the exchange can proceed through 3 or Ru(CO) 3 (H 2 O) 2 OH + with k Ru CO and k RuOH CO of, respectively, 0.003 ( 0.002 and 0.024 ( 0.003 s -1 , with a ruthenacarboxylic acid intermediate.