CTAB对四-(4-N-甲基吡啶)卟啉SERS谱的影响

Effect of CTAB on the Surface-Enhanced Raman Scattering of Tetrakis(4-N-methylpyridyl)porphyrin

研究了阳离子表面活性剂十六烷基三甲基溴化铵 (CTAB)对四 ( 4 N 甲基吡啶 )卟啉 (H2 TMPyP)及其银配合物 (AgTMPyP)在Ag胶中的表面增强拉曼散射 (SERS)谱的影响 .SERS光谱表明 ,吸附于Ag胶粒的H2 TMPyP与衬底银原子结合形成AgTMPyP ,加入CTAB后 ,部分AgTMPyP表面络合物还原为H2 TMPyP .相似的去金属化反应也出现在AgTMPyP/Ag胶 /CTAB体系中 .CTAB的加入使SERS谱带强度明显增加 .

Surfactants have significant effects on the properties of liquid-solid surfaces. The effects of surfactants on the surface-enhanced Raman scattering ( SERS) of molecules adsorbed on solid substrates have been used to improve the qualities of SERS spectra and to reveal the distance-enhancement relationship of SERS. On the other hand, the adsorption behaviors of porphyrin compounds on surfaces are important for their applications in electrode modification, sensitization of photo-electric transduers, and biomimetic catalysis. The effect of cetyltrimethyl ammonium bromide ( CTAB) on the SERS of free-base 5,10,15,20-tetrakis(4-N-methylpyridyl) porphyrin ( H2TMPyP) and its Ag-chelate ( AgTMPyP) adsorbed on Ag colloid was studied. It was found from the SERS spectra that the adsorbed H2TMPyP molecules undergo silver-incorporation to form AgTMPyP which can change back to H2TMPyP when added CTAB. The similar demetallization reaction was aslo observed in AgTMPyP/Ag soL/CTAB systems. The SERS signals were found to be obviously enhanced when added CTAB. The implications of the findings in relation to the change of micro-environment on Ag particles by the addition of CTAB are briefly discussed.