Sorption and spontaneous ionization of phenothiazine within channel type zeolites: Effect of the confinement on the electron transfers.
Sorption and spontaneous ionization of phenothiazine within channel type zeolites: Effect of the confinement on the electron transfers.
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DOI：
10.1039/c1ra00220a
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发表时间：
2011-08
期刊：
影响因子：
3.9
通讯作者：
F. Luchez;S. Carré;A. Moissette;O. Poizat
中科院分区：
文献类型：
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作者：
F. Luchez;S. Carré;A. Moissette;O. Poizat
紫外-可见漫反射吸收和拉曼散射实验数据表明，吩噻嗪（PTZ）在具有不同拓扑结构的三种中孔酸性沸石（镁碱沸石（H-FER）、H-ZSM-5和丝光沸石（H-MOR））的直孔道中存在吸附和自发电离现象。的光谱数据突出的限制和局部静电场的吸附和电荷分离动力学的综合影响。PTZ掺入和电离似乎在较大孔H-MOR中比在H-ZSM-5和H-FER中更快。然而，吸附和电离几乎完成后，在三种沸石约一年。PTZ的低电离电位值（I. P.= 6.73 eV）诱导了在每个通道结构的内部空间内以高产率准瞬时形成自由基阳离子PTZ·+。然而，H-FER的10元环（10-MR）通道提供的更高的限制效应和更高的极化效应有利于PTZ二次电离形成二价阳离子PTZ 2+。这些电荷分离态的非常长的寿命可能是由于PTZ在窄通道中的受限流动性和被捕获的电子远离PTZ电离的初始位点的区室化。然而，一个非常缓慢的电荷重组过程中观察到的三种沸石形态约一年后。该反应仅在H-FER和H-ZSM-5的较窄孔中是部分的，而在较大孔H-MOR内的较快扩散过程导致2年后准全部阳离子消失。因此，反应机理清楚地表明，PTZ·+和PTZ 2+只是中间体，并且药物稳定的最终产物是封闭的PTZ分子。
Diffuse reflectance UV-visible absorption and Raman scattering experimental data show evidence of the phenothiazine (PTZ) sorption and spontaneous ionization in the straight channels of three medium pore acid zeolites with various topologies (ferrierite (H-FER), H-ZSM-5 and mordenite (H-MOR)) but analogous Si/Al contents. The spectral data highlight the combined effects of confinement and local electrostatic field on the sorption and charge separation kinetics. The PTZ incorporation and ionization appeared to be quicker in the larger pore H-MOR than in H-ZSM-5 and in H-FER. However, sorption and ionization are almost complete in the three zeolites after about one year. The low ionization potential value of PTZ (I.P. = 6.73 eV) induced quasi instantaneous formation of the radical cation PTZ•+ in high yield within the internal space of each channel structure. Nevertheless, the higher confinement effect and higher polarizing effect offered by the 10-membered rings (10-MR) channels of H-FER favoured the PTZ second ionization to form the dication PTZ2+. The very long lifetimes of these charge separated states are probably due to the restricted mobility of PTZ in the narrow channels and to the compartmentalization of the trapped electron away from the initial site of PTZ ionization. However, a very slow charge recombination process is observed within the three zeolite morphologies after about one year. This reaction is only partial in the narrower pores of H-FER and H-ZSM-5 whereas the faster diffusion process within the larger pore H-MOR induces quasi total cation disappearance after 2 years. Therefore, the reaction mechanism indicates clearly that PTZ•+ and PTZ2+ are only intermediates and that the thermodynamically stable end product is the occluded PTZ molecule.