Research On Preparation And Properties Of Optical Absorbing Materials Based On Squaraine

With the rapid development of solar energy industry, the demands for quantity and quality of photoelectric functional materials are dramatically increasing. Among various optical absorbing materials, squaraine owns lots of unique advantages, i.e. strong absorption from visible to the near-infrared region (ε≥105L·mol-1·cm-1), photostability, low band gap energy (EG), and easily modified structures. There are many symmetrical squaraines reported in literatures.But unsymmetrical squaraines, especially squaraine-based macromolecules are rarely reported in the literatrues up to now. In this paper, semi-squaraine, symmetrical, unsymmetrical squaraines and a squaraine-based macromolecule were designed, synthesized, and characterized by FT-IR,1H-NMR. The optimal conditions for reaction were determined and relations between the molecular structures and optical properties were discussed. On that basis, the quinoline semi-squaraine has been successfully applied in colormetic analysis of Hg2+. The main contents of this dissertation include the following points:1. The development of squaraine dyes and especially the status, synthesis method and application of the symmetrical and unsymmetrical squaraine dyes were reviewed in detail.2. Semi-squaraine, symmetrical and unsymmetrical squaraines based on quinoline were designed and synthesized by the method of squaric acid ester with high yield, and then their structures were characterized by FT-IR,1H-NMR. The optimal conditions for reaction were discussed by UV-Vis absorption spectra.3. In order to study the relations between molecular structures and optical properties, the molar absorption coefficient, the wavelength of maximum absorption and aggregation effect of squaraine dyes were studied. The results reveal that squaraine dyes have good optical absorbing properties. With the introduction of electron-donating groups, the squaraine will possess lower bandgap and longer wavelength of maximum absorption. Furthermore, the selective recognition of semi-squaraine (SSQ) to Hg2+was studied and the recognition mechanism was confirmed by the calculation result obtained from B3LYP/6-31G level of theory.4. With different feed ratios of squaric acid and phloroglucinol, a symmetrical squaraine and a squaraine-based macromolecule were designed and synthesized. An unsymmetrical squaraine was also designed and synthesized with semi-squaraine and phloroglucinol. Their structures were characterized by FT-IR,1H-NMR. The results of UV-Vis absorption and FL spectroscopy show that the squaraine was solvent and pH sensitive. The unsymmetrical squaraine has lower bandgap, longer UV-Vis absorption wavelength and fluorescence emission wavelength. The UV-Vis, FL, DSC and TGA results show that the squaraine-based macromolecule is a low bandgap, good optical absorbing material with high thermal stability.