Second-order nonlinear optical properties of poled coumaromethacrylate copolymers

Study of Photophysical Properties on Newly Synthesized Coumarin Derivatives

Herein, we have studied the photophysical properties for three newly synthesized coumarin derivatives; 4-((2,6-dibromo-4-methylphenoxy)methyl)-2H-benzo[h]chromen-2-one (DMB), 4-((3,4-dihydro-6,7-dimethoxyisoquinolin-1-yl)methyl)-6-methyl-2H-chromen-2-one (DIM) and 4-((p-tolyloxy)methyl)-6-methoxy-2H-chromen-2-one (TMC). The absorption and emission spectra for above said molecules were recorded in different solvents at room temperature in order to calculate their ground and excited state dipole moments. The ground (μ _g ) and excited state dipole (μ _e ) moments of these coumarin derivatives were calculated using Lippert's, Bakshiev's and Kawski-Chamma-Viallet's equations by the solvatochromic shift method, which involves a variation of Stokes shift with the solvent dielectric constant and refractive index. Ground state dipole moments (μ _g ) were also calculated from the Guggenheim method using the dielectric constant and refractive index of the solute molecule. The value of ground state dipole moment obtained from these two methods is well correlated. Further, it is notified that the excited state dipole moment is larger than the ground state dipole moment for all three solute molecules. It inferred that the excited state for above said molecules is more polar than the ground state. The present investigations may shine in the design of nonlinear optical materials. Graphical Abstract The photophysical properties for novel coumarin derivatives were studied in different solvents.Ground and excited state dipole moments were estimated by the solvatochromic shift method. The excited state dipole moment is greater than the ground state dipole moment in systems studied. The excited state is more polar than the ground state. The present investigation may be shine in the design of non linear optical materials.

Chitosan containing azo-based Schiff bases: thermal, antibacterial and birefringence properties for bio-optical devices

Chitosan Azo derivatives show characteristic birefringence property.

Study of film structure and adsorption kinetics of polyelectrolyte multilayer films: effect of pH and polymer concentration

The alternate adsorption of polycation poly(allylamine hydrochloride)(PAH) and the sodium salt of the polymeric dye poly(1-[ p-(3'-carboxy-4'-hydroxyphenylazo)benzenesulfonamido]-1,2-ethandiyl)(PCBS) on quartz crystals coated with silica was studied to understand the structural properties and adsorption kinetics of these films using a combination of quartz crystal microbalance with dissipation monitoring (QCM-D), absorbance, and ellipsometry measurements. In-situ deposition of the polycation PAH on QCM crystals was monitored, followed by rinsing with water and then deposition of the polyanion PCBS. The effects of polymer concentration and pH on film structure, composition and adsorption kinetics were probed. The polymers were adsorbed at neutral pH conditions and at elevated pH conditions where PAH was essentially uncharged to obtain much thicker films. The change in the resonant frequency, Deltaf, of the QCM-D showed a linear decrease with the number of bilayers, a finding consistent with absorbance and ellipsometric thickness measurements which showed linear growth of film thickness. By using the Delta f ratios of PCBS to PAH, the molar ratios of repeat units of PCBS to PAH in the bilayer films as determined by QCM-D were approximately 1:1 at polyelectrolyte concentrations 5-10 mM repeat unit, indicating complete dissociation of the ionic groups. The frequency and dissipation data from the QCM-D experiments were analyzed with the Voigt model to estimate the thickness of the hydrated films which were then compared with thicknesses of dry films measured by ellipsometry. This led to estimates of the water content of the films to be approximately 45 wt %. In addition to the QCM-D, some films were also characterized by a QCM which measures only the first harmonic without dissipation monitoring. For the deposition conditions studied, the deposited mass values measured by the QCM's first harmonic were similar to the results obtained using higher harmonics from QCM-D, indicating that the self-assembled polyelectrolyte films were rigid.

Star-Shaped Azo-Based Dipolar Chromophores: Design, Synthesis, Matrix Compatibility, and Electro-optic Activity

Three new azo-benzene-based push-pull chromophores with dendritic architecture were synthesized as active materials for electro-optic applications. These chromophores were synthesized in six or seven synthetic steps with an overall yield of around 80% per step and high purity. UV-vis spectroscopy showed significant influence of the transient dipole moment on the observed r(33) values. The chromophores were stable to photochemical oxidation in ambient light and air. The electrical poling conditions were optimized for each chromophore as the T(g) of the composite material varied significantly. The highest EO coefficient achieved was 22-25 pm/V at 1550 nm wavelength. STEM analysis of the blends enabled the correlation of the activity of these large chromophores with the blend morphology. An amorphous polycarbonate host effectively disperses the chromophores in 2-20 nm aggregates in the active materials. However, macrophase separation into 200-500 nm aggregates was observed in a methacrylate host matrix.