Effects of Two-Photon Fluorescence and Polymerization on the First Hyperpolarizability of an Azobenzene Dye

Abstract

The technique of hyper-Rayleigh scattering (HRS) has been employed to investigate the first hyperpolarizability (β) of the azo dye Disperse Red 19 and a polymer in which Disperse Red 19 appears as a side-chain moiety. In addition to HRS, these two molecules were found to exhibit substantial two-photon-induced fluorescence (TPF). The TPF spectra for these molecules were measured, and corrected HRS intensities were obtained. Using an external reference method, β values of (1480 ± 100) × 10-30 and (1470 ± 90) × 10-30 esu were determined for the dye and polymer systems, respectively, in dimethyl sulfoxide at 1064 nm. The difference between these two values is very small and shows that the effect of polymerization on the HRS intensity, in the dilute concentration limit, is negligible.

Structure−Property Dependence of the First Hyperpolarisabilities of Organometallic Merocyanines Based on the μ-Vinylcarbynediiron Acceptor and Ferrocene Donor

“…[22] A fluorescence signal should have a considerably broader line than the sharp HRS signal ( Figure 6) and the maximum of the emission band occurs infrequently at λ/ 2. [62,68,69] Overall the β values obtained for this series of cationic ferrocenyl chromophores are exceptionally high, but they have been rigorously checked for TPAF and show no enhancement.…”

“…[62] Also, numerous techniques have been developed to avoid or abstract the TPAF contribution to β: long wavelength measurement, [63Ϫ65] time-resolved HRS, [66] high-frequency demodulation [67] and the measurement of the TPAF spectrum to abstract the fluorescence contribution to the HRS signal. [68,69] The HRS experiments were carried out in CH 2 Cl 2 solution at 1064 nm fundamental wavelength using p-nitroaniline (pNA) as an external reference. The calculated β values of the complexes 13؊22 are presented in Table 3.…”

On the Rigidity of Polynorbornenes with Dipolar Pendant Groups

“…The light-tan precipitate was filtered, washed with water, dried, and recrystallized from EtOAc/CHCl 3 to yield 14 (1.91 g ,75 %): m.p. 310 8C (decomp); IR (KBr): nL= 3387, 2958, 2864, 2541, 1715, 1651, 1660 ,1600, 1383, 1279, 1180, 1019, 799 4,47.1,50.5,52.1,60.0,110.8,117.6,130.2,135.9,151.3,171.3 ppm;HRMS (FAB) 4-(4-aza-tricyclo[5.2.1.0 2,6 ]dec-8-en-4-yl)benzoate (10): Oxalyl chloride (1.8 mL, 20 mmol) and DMF (1 drop) were added to a solution of 14 (2.55 g, 10 mmol) in CH 2 Cl 2 at 0 8C. The mixture was gradually warmed to room temperature and then stirred for 3 h. The solvent was removed www.chemeurj.org in vacuo to give the corresponding acid chloride, which was dissolved in THF (50 mL).…”

“…[1][2][3][4] For example, when chromophores are organized as the side groups of poly(isocyanide)s, the first hyperpolarizabilities b o of the polymers are increased.…”

“…[1] The key to the success of this strategy relies on the helical conformation of the polymer backbone, [1][2][3][4] which leads to a strong orientational correlation of the side groups. In a preliminary communication, we reported that polynorbornenes (PNBs) derived from the ring-opening metathesis polymerization (ROMP) [5,6] of norbornene derivatives with dipolar pendant groups [7] exhibit molecular-weight-dependent b o values as measured by hyper-Rayleigh scattering (HRS) methods.…”