Synthesis and Study of Novel Chemosensing Probes for Selective Detection of Metal Ions and Ru-Based Supramolecular Dendrimers for Solar Cell Applications

• Main Authors: Satapathy, Rudrakanta, 盧達侃
• Other Authors: Lin, Hong-Cheu
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/44588227673037715584

博士 === 國立交通大學 === 材料科學與工程學系 === 100 === Abstract The main objective of this dissertation is to synthesize novel chemosensing binding probe for selective detection of metal ions. In the introduction of the thesis we have described about several chemosensing mechanisms and the advantages of polymeric cheosensors over small molecular analogue. Several sensing probes have been developed for selective sensing of Pb2+, Hg2+, and Zn2+. Here we have developed novel thieno-benzo-imidazole based small molecules for the sensing of toxic metal ion Pb2+ in aqueous solutions. Again, we discussed about thieno-imidazole based homopolymer for the colorimetric detection of Hg2+ and fluorometric detection of Zn2+. Furthermore, we discussed about the amendment of sensitivity of chemosensing polymers upon variation of their attached imidazole based pendants. In addition to these novel chemosensing moieties, we synthesized mono, bis, and tris Ru containing thiophene dendrimers for the application in photovoltaic cell. In the first chapter we synthesized two novel dithieno-benzo-imidazole-based compounds (M2 and A2), which showed remarkable sensitivities towards Pb2+ by 12-fold enahancement and 10-fold decay of fluorescence, respectively, in aqueous solutions. Substituent effects of different dithieno-benzo-imidazole-based moieties (M1, M2, A1, and A2) on the quantum yields, fluorescence lifetimes and sensitivities to Pb2+ along with the reversibilities by S2- were investigated. In the second chapter we synthesized novel thieno-imidazole-based polymer P, which showed both colorimetric, and ratiometric detections of Hg2+ as well as fluorometric detection of Zn2+ via fluorescence turn-on response with augmented lifetime. Its model polymer M did not show any such sensing capability under similar conditions, which further confirmed the unique sensitivity of P towards Hg2+ and Zn2+ via the chelation of metal ions to both ‘S’ and ‘N’ hetero-atoms. In the third chapter three novel electron donor-acceptor conjugated polymers (P1-P3) with various imidazole pendants were synthesized, and their excellent photo-physical along with electrochemical properties led them to become suitable transduction materials for chemosensing applications. Herein, polymers (P1-P3) showed remarkable sensing capabilities towards H+ and Fe2+ in semi-aqueous solutions. Upon titration with H+, polymers P1 and P2 showed hypsochromic shifts of absorption and PL maxima with enhanced fluorescence intensities. However, P3 showed diminished abosorption as well as fluorescence intensities under similar conditions due to static quenchning. The anomalous behaviour of P3 compared with P1 and P2 was clarified by the electronic distributions via computational analysis. Furthermore, P3 (Ksv= 1.03×107) showed the best sensing ability towards Fe2+ compared with P1 (Ksv= 2.01×106) and P2 (Ksv= 4.12×106) due to its improved molecular wire effect. Correspondingly, fluorescence lifetime of P3 was decreased intensively (almost 11 times) than polymers P1 (4.6 times) and P2 (6.2 times) in the presence of Fe2+. By means of fluorescence on-off-on tactics, the chemosensing reversibilities in protonation-deprotonation and metallation-demetallation were achieved by triethylamine (TEA) and disodium salt of ethylenediaminetetraacetic acid (Na2-EDTA)/phenanthroline, respectively, as the suitable counter ligands. 1H NMR titrations revealed the unique behaviour of P3 compared with P1 and P2. To the best of our knowledge, no reports of Fe2+ sensors were provided by solo imidazole receptors conjugated to the main chain polymer with diverse sensitivity pattern depending on their attached substituents. In the fourth chapter mono (G1RuG1, G2RuG2, G3RuG3), bis (BT2RuG1, BT2RuG2, BT2RuG3) and tris (TPA3RuG1, TPA3RuG2, TPA3RuG3) ‘Ru’ containing supramolecular thiophene dendrimers were constructed. Their photophysical, electrochemical and thermal properties were investigated. Due to the donor-acceptor, benzothiadiazole-hexyl thiophene cored architecture in bis ‘Ru’ containing thiophene dendrimers, these showed higher photovoltaic efficiency than other two series. Tris ‘Ru’ containing architecture with terthiophene-triphenylamine core, showed moderate photovoltaic performance due to their star shaped branched structure. Among the three generations (G1-G3) of bis ‘Ru’ containing dendritic series, BT2RuG3 showed the highest solar cell efficiency 0.77% without the aid of any additives or anealing conditions. This solar cell efficiency value is the highest among all metal containing dendritic supramolecule reported so far. Thus in the conclusion, novel chemosensing probes for the selective and sensitive detection of metal ions has been developed. Amendments of sensitivity pattern upon the variation of substituents were discussed. Synthesis and photovoltaic properties of metal containing thiophene dendrimers were described.