Synthesis of Polynorbornene Based Molecular Self-Assembly for the Detection of Copper Ions Present in the Environmental Water Samples

Abstract

Metal-assisted molecular self-assembly finds applications in optoelectronics, chemical sensing and catalysis. In this article, fluorescein based polynorbornene is synthesized and its molecular self-assembly is used to detect the presence of copper (II) ions in environmental water samples (pond waters). First of all, the sequential procedures of the synthesis of norbornene and polynorbornene are accomplished using simple organic compounds available in the Indian market. Various intermediate compounds and norbornene are characterized by 1H NMR and 13C NMR techniques. Structure of polynorbornene is proved by 1H NMR spectroscope. Molecular weight of polynorbornene is obtained using Acquity advanced polymer chromatography. Particle size of polymer nano-aggregates is derived by using FESEM microscope. This polynorbornene (PNor-Flu) is used for the selective and sensitive detection of the copper(II) ions with an excellent LOD of 0.27 µM, far below the limit decided by the Environmental Protection Agency (EPA) of USA. This is achieved with the help of UV-Vis studies and spectroscopic titrations using OD416/OD350. As far the self-assembly is concerned using microscopic analysis, polynorbornene with a higher number of hydroxyl groups shows rod-like self-assembly. Polynorbornene structure is again transformed to a spherical shape in the presence of the copper(II) ions even in micromolar concentration. From this change, it is believed that the poynorbornene has a high potentiality for sensing the copper(II) ions, which helps it to impart unique morphological properties. From the tests performed on real water samples, polynorbornene has proved its high efficiency of selective and sensitive detective power for detecting copper (II) ions in pond waters.