In-Situ Measurements and Molecular Orientation by External Reflection Spectrometry of Liquid-Liquid Interfacial Adsorbates of Porphyrins.

本文利用部分反射光谱法研究了质子化的亲脂卟啉（H_4PX_2）在惰性有机溶剂/无机酸（HX）水溶液界面上的吸附状态。包括外反射（ER）和部分内反射（PIR）. 1.质子化四苯基卟啉聚集体（H_4PX_2）的化学计量分析使用包括液体池和棱镜的简单装置来完成。(1)In在甲苯-4M H_2SO_4体系中，电流变光谱法能有效地区分有机相（H_2P）_0中的界面吸附物和亲脂性溶质。(2)In在十二烷-4M H_2SO_4体系中，（H_2P）_o全部被质子化，生成（H_4PX_2）_n，i和水相H_4P^&lt;2+&gt;_<aq>。各吸收带的反射吸光度与界面分子密度[H_4PX_2]_i的关系表明，界面吸附状态由单层状态转变为单层状态 ...更多信息 具有不同反射系数的多层膜。（3）在十二烷-4M H_2SO_4体系中，饱和界面分子密度为1.20×10 ~（-1）<-10>mol·cm ~（-1）<-2>;吡咯环平面相对于界面法线的倾斜角为47°。而质子化的四对甲苯基卟啉则可以缔合形成聚集体。这表明分子缔合是依靠苯基的旋转性质产生平面型分子结构的。3.利用自制的变角装置研究了反射光谱的入射角依赖性。在p偏振PIR谱中观察到正负带，其带位置与p偏振ER谱中的带位置相对应。然而，p-PIR谱带的符号与p-ER谱带的符号相反。这说明p-PIR光谱的界面选择规律与p-ER的界面选择规律相反，PIR也可用于分子取向的分析。少

The authors investigated the interfacial adsorption states of lipophilic-porphyrins (H_2P) in a protonated form (H_4PX_2) at the inert organic solvent/aqueous inorganic acid (HX) solution interface by development of in situ measurement devices for partial reflection spectrometry, including external reflection (ER) and partial internal reflection (PIR).1.Stoichiometric analysis of protonated tetraphenylporphyrin in an aggregate (H_4PX_2)_<n,i> was accomplished using a simple device comprising a liquid cell and prisms. (1)In the toluene-4 M H_2SO_4 system, ER spectrometry was effective to distinguish interfacial adsorbates from lipophilic solute in the organic phase (H_2P)_o. (2)In the dodecane-4 M H_2SO_4 system, all (H_2P)_o was protonated to yield (H_4PX_2)_<n,i> and aqueous species, H_4P^<2+>_<aq>. The relationship of reflection absorbance at each of bands for interfacial molecular density [H_4PX_2]_i suggested that the interfacial adsorption state changed from a monolayer form to a … More multilayer one with a different reflection coefficient. (3)The saturated interfacial molecular density in the dodecane-4 M H_2SO_4 system was estimated to be 1.20×10^<-10> mol cm^<-2> ; it yields a tilt angle 47°of pyrrole ring plane against the interface normal.2.No aggregation was found in the lipophilic tetraphenylporphyrin derivatives with substituent at ortho-position in meso-phenyl group. Whereas, protonated tetra-p-torylporphyrin could associate to form some aggregate. These suggest the molecular association is depend on the rotation nature of phenyl-group to yield a planar-type molecular structure.3.The incident angle dependence of reflection spectra was studied using a home-made variable-angle device. Positive and negative bands have been observed in the p-polarized PIR spectra, whose band location correspond to those in p-polarized ER spectra. Nevertheless, the bands in the p-PIR exhibited reversed sign to those of p-ER spectra. These suggest that the interface selection rule of the p-PIR spectrometry has a reversal rule of p-ER, and PIR can also be used for the analysis of molecular orientation. Less