Oxazole Dyes With Potential For Photoluminescence Bioprobes: A Two-Photon Absorption Study

In this work, six π-conjugated oxazole compounds dissolved in dichloromethane were characterized with linear and nonlinear optical measurements. Z-scan with femtosecond laser pulses was employed to determine the two-photon absorption (TPA) spectra. Other photophysical parameters, such as absorbance, solvatochromism, lifetime fluorescence, and fluorescence anisotropy, were evaluated with linear optical techniques. The experimental TPA cross section spectra were adjusted by the sum-over-states (SOS) model, by which important parameters such as transition dipole moments and broadening parameters were determined. To better understand the TPA spectra of the oxazole compounds, quantum-chemical calculations using the response function formalism and the density functional theory level of theory were performed. Using the results provided by the quantum-chemical calculations and the broadening parameters estimated through the application of the SOS model, the TPA spectra were simulated by the superposition (summation) of individual homogeneous Lorentzian absorption profiles

Understanding the Effect of Deposition Technique on the Structure–Property Relationship of Polyaniline Thin Films Applied in Potentiometric pH Sensor

The comprehension of potentiometric pH sensors with polymeric thin films for new and advanced applications is a constant technological need. The present study aimed to explore the relationship between the sensitivity and correlation coefficient of potentiometric pH sensors and the structure–property relationship of polyaniline thin films. The effect of the deposition method on the sample’s properties was evaluated. Galvanostatically electrodeposited and spin-coated polyaniline thin films were used as the sensing stage. Samples were electrodeposited with a current density of 0.5 mA/cm2 for 300, 600, and 1200 s and were spin coated for 60 s with an angular velocity of 500, 1000, and 2000 rpm. The electrodeposited set of films presented higher average sensitivity, 73.4 ± 1.3 mV/pH, compared to the spin-coated set, 59.2 ± 2.5 mV/pH. The electrodeposited films presented higher sensitivity due to their morphology, characterized by a larger roughness and thickness compared to spin-coated ones, favoring the potentiometric response. Also, their oxidation state, evaluated with cyclic voltammetry and UV-VIS spectroscopy, corroborates their sensing performance. The understanding of the structure–property relationship of the polymeric films affecting the pH detection is discussed based on the characteristics of the deposition method used

Primera hiperpolarizabilidad electrónica molecular de dos tintes de oxazoles en solución.

Two π-conjugated oxazoles compounds dissolved in toluene were characterized by the hyper-Rayleigh scattering technique in order to determine the value of the first molecular hyperpolarizability (βHRS). Quantum-chemical calculations using time-dependent density functional theory level were performed to calculate the static and dynamic βHRS theoretical values. Experimental βHRS have shown values of about 42 × 10 −30 cm 4 statvolt −1 and 31 × 10 −30 cm 4 statvolt −1 for both organic compounds, which are in a satisfactory accordance with the calculated results.Dos compuestos oxazoles conjugados con π disueltos en tolueno se caracterizaron por la técnica de dispersión Hyper-Rayleigh para determinar el valor de la primera hiperpolarizabilidad molecular (βHRS). Para calcular los valores teóricos estáticos y dinámicos de βHRS se realizaron cálculos cuántico-químicos utilizando el nivel de teoría funcional de la densidad dependiente del tiempo. Los βHRS experimentales han mostrado valores de aproximadamente 42 × 10 −30 cm 4 statvolt −1 y 31 × 10 −30 cm 4 statvolt −1 para ambos compuestos orgánicos, que están en una conformidad satisfactoria con los resultados calculados

Oxazole Dyes With Potential For Photoluminescence Bioprobes: A Two-Photon Absorption Study

In this work, six π-conjugated oxazole compounds dissolved in dichloromethane were characterized with linear and nonlinear optical measurements. Z-scan with femtosecond laser pulses was employed to determine the two-photon absorption (TPA) spectra. Other photophysical parameters, such as absorbance, solvatochromism, lifetime fluorescence, and fluorescence anisotropy, were evaluated with linear optical techniques. The experimental TPA cross section spectra were adjusted by the sum-over-states (SOS) model, by which important parameters such as transition dipole moments and broadening parameters were determined. To better understand the TPA spectra of the oxazole compounds, quantum-chemical calculations using the response function formalism and the density functional theory level of theory were performed. Using the results provided by the quantum-chemical calculations and the broadening parameters estimated through the application of the SOS model, the TPA spectra were simulated by the superposition (summation) of individual homogeneous Lorentzian absorption profiles