绿色植被红边特征的研究

通过系统分析绿色植被在紫外可见波段光谱的产生机理,得出绿峰和红边是由叶绿素产生的.从叶绿素的结构上看,它属于卟啉类化合物,为了进一步探究红边产生的机理,合成了四苯基卟啉、四(4-甲氧基苯基)卟啉、四(4-磺酸钠苯基)卟啉、四吡啶基卟啉、四甲基卟啉、四(4-甲氧基苯基)卟啉合锌和四(4-甲氧基苯基)卟啉合铜,并采用紫外可见光谱、红外及核磁进行表征.通过对其紫外可见光谱的系统分析,提出"红边"不仅限于叶绿素,而是卟啉类化合物特有的光谱特征,红边是由卟啉环a2 u(π)-eg(π*)跃迁产生的Q带所致.其位置不仅与卟啉的浓度相关,与卟啉化合物外侧取代基类型也有关系,金属卟啉对红边的位置影响较大.

The Study for Formation Mechanism of Spectral Red Edge of Green Vegetation

Red edge of green vegetation is caused by strong chlorophyll absorption ,and its position shifts to long-wavelength with the increase of chlorophyll .Chlorophyll ,including chlorophyll a and b ,belongs to porphyrin derivative in molecular structure .Therefore ,it is found that the other synthesized porphyrin may also is of red edge property .In order to study the formation mechanism of red edge ,a serious of porphyrins and metalloporphyrins including Tetraphenylporphyrin ( TPP ) , Tetrakis-(4-methoxyphenyl ) porphyrin (TMPP) ,Tetrakis-(4-sulfophenyl) porphyrin (Na4 TPPS) ,Tetrapyridylporphin (TPyP) ,Tetramethylpor-phyrin (TMP) ,Tetrakis-(4-methoxyphenyl)porphyrin zinc (ZnTMPP) and Tetrakis-(4-methoxyphenyl) por-phyrin copper (CuTMPP) were synthesized and characterized by UV-Vis-NIR ,FT-IR and 1 H NMR .With systematically analysis of their UV-Vis spectrum (absorption ,transmittance and solid reflectance) ,we found that porphyrins or metalloporphyrins can also cause the red edge similar to chlorophyll .The red edge is caused by strong Q band absorption of porphyrins ,and red edge is right slope of absorptionvalley in their UV-Vis transmittance spectrum .The red edge position is related to the concentration of porphyrin ,the substituents on the porphyrin ring ,and the center metal of metalloporphyrins .Red edge position will shift to short-wavelength when phenylic H is substituted by electron-withdrawing group ,and shift to long-wavelength when substituted by electron-donating group as well as increasing concentration of porphyrins .The change of substituent group in porphyrins ring is influence more obviously than the change of substituent groups in benzene ring of TPP . The number of Q bands will decrease when metal ions insert to porphyrin ring .Therefore ,red edge position-will be strongly influenced by metalloporphyrins .