Seminar by Dr. Pham Thi Thu Thao and MSc. Pham Nguyen Nhu Quynh

On November 22, 2024, the lectures from Dr. Pham Thi Thu Thao and MSc. Pham Nguyen Nhu Quynh takes place on the 5th Floor of the Library with detailed content as follows:

Dr. Pham Thi Thu Thao presents about "Mechanisms and Kinetics of Glyphosate Degradation by Hydroxyl Radicals (OH) – Application in the Treatment of Pesticide Residual Pollution"

Abstract:

Glyphosate (C3H8NO5P), a phosphonate compound, is the most widely used synthetic herbicide globally. First developed in the 1970s, it is now extensively applied in agriculture. However, the residual presence of glyphosate in the environment can pose significant risks to human health and ecosystems. Therefore, studying methods for glyphosate degradation is crucial. Glyphosate's unique chemical structure enables it to function as an enzyme inhibitor. It works by preventing the synthesis of essential amino acids, ultimately leading to plant death. Glyphosate is absorbed through leaves and roots and then translocates to other parts of the plant, inhibiting growth and development. One of the methods for degrading glyphosate involves the use of hydroxyl radicals (•OH). These radicals can be generated from photochemical reactions or oxidation processes in the environment. Chemical kinetics has become a valuable tool for assessing the mechanisms of chemical reactions by examining the rate constants of various processes within the reaction. Kinetic studies are essential in understanding and applying degradation processes for organic compounds. Understanding the factors that influence reaction rates enables the control and optimization of these processes.In this study, the kinetics of the degradation reaction were analyzed by measuring the rates of reactions occurring during treatment, aiming to optimize the conditions for maximum efficiency. This also allows for the prediction of degradation products of the pesticide. This aspect is critical, as the degradation products could be more or less toxic than the original compound. Kinetic studies of degradation reactions help evaluate the decomposition rate, accumulation time in the environment, and potential harm to organisms. Based on the study's findings, the potential for effectively addressing residual pesticide pollution can be assessed, minimizing environmental impacts.

MSc. Pham Nguyen Nhu Quynh presents about "Solvatochromic fluorescent ethynyl naphthalimide derivatives for detection of water in organic solvents"

Abstract:

Three new derivatives of (4-methoxyphenyl) ethynyl-naphthalimide were synthesized by Sonogashira coupling reaction. These compounds showed robust and strong fluorescent signals, which shift from blue to orange as the solvent polarity increases. Computational calculations revealed that in low-polarity solvents, the molecules preferred a 90° rotation between the naphthalimide and ethynyl benzene fragments. In high-polarity solvents, where the energy barrier for rotation of the alkyne bond was higher, the molecules favored the 0° conformer, leading to longer emission wavelengths. The compound with a 2-methoxyethyl group tethered to the naphthalimide nitrogen demonstrated sensitivity to water presence in the ranges of 0–30 % (v/v) in THF, 0–15 % (v/v) in DMSO, 0–30 % (v/v) in MeCN, 0–15 % (v/v) in acetone, and 0–40 % (v/v) in EtOH. The detection limits for water were determined to be 0.0523 %, 0.1365 %, 0.0337 %, 0.0570 %, and 0.1170 % (v/v) in THF, DMSO, MeCN, acetone, and EtOH, respectively. The effectiveness of this compound in quantifying ethanol content in spirit samples was successfully demonstrated.