The Photochemical And Electrochemical Studies On Several Squaraine Dyes Compounds

Squaraines (SQ) belong to a novel class of organic dyes which have a squaricacid core and symmetric or unsymmetric conjugate structure. The squaraine dyebackbone is a resonance stabilized zwitterionic structure with intense absorption andemission properties in the visible to near-IR wavelength range. However, theelectrochemistry applications of squaraines were not so many. The electrochemicalproperties of several squaraine dyes were studied in this paper. In this study, the ECLof BDPSQ was investigated firstly. Then the properties of electro-catalyticdegradation of Ind-SQ were studied on Pt electrode, the degradation mechanismswere discussed. Finally, the host-guest interactions of ferrocenes and cucurbit [7] urilwere investigated. The thesis included four chapters.In the first chapter, the background, current research and application of squarainedyes, electrochemiluminescence (ECL) and cucurbituril in analytical chemistry andother fields were summarized, and the commonality among the three parts wereintroduced. The aims and research topics of this thesis were finally proposed.In the second chapter, the ECL of BDPSQ was investigated in chloroform on Ptelectrode, BDPSQ undergo two redox reactions at0.87V and1.25V assigned to theredox steps of N, N-dimethylanilino moieties. Comparing the fluorescence spectrumwith ECL spectrum and the influence of synthetic materials, solvents and supportingelectrolyte, and the mechanism of ECL was proposed.For the third chapter, we studied the electrochemistry of Ind-SQ using CV andSWV methods, Ind-SQ undergo two redox steps at0.50V and0.75V. The degradationproducts were investigated by UV-Vis spectroscopy, the characteristic peaksdecreased and a new peak at410nm appeared and then increased, it indicated that theInd-SQ was degraded when potentials were applied. Then FTIR was used to study thedegradation procedure in positive potential, a possible mechanism for the degradationpathways of squaraine was proposed. This provided a theoretical basis andexperimental means for handling the dye pollutants.In the forth chapter, the host-guest chemistry of FcSQ and FcIP with cucurbit [7]uril were studied, we found that it was not a suitable method for these systems using UV-Vis and fluorescence spectrums. Then, the interaction was studied betweenferrocene methanol and cucurbit [7] uril through the changes of CVs and DPVs. Forferrocene methanol had always been used as a quencher to the ECL systems ofRu(bpy)32+/TPrA, so ECL method was used to investigate the host-guest interactions.The results showed that cucurbit [7] uril enhanced the quenching effect, the possiblemechanism was hypothesized.