Linear Dichroism of Zn(II)-Tetrapyridylporphine Aggregates Formed at the Toluene/Water Interface
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- 作者：Hideaki Takechi ; Kenta Adachi ; Hideaki Monjushiro ; Hitoshi Watarai
- 刊名：Langmuir
- 出版年：2008
- 出版时间：May 6, 2008
- 年：2008
- 卷：24
- 期：9
- 页码：4722 - 4728
- 全文大小：494K
- 年卷期：v.24,no.9(May 6, 2008)
- ISSN：1520-5827
文摘
The apparent circular dichroism (CD) and the linear dichroism (LD) spectra of the aggregates of achiral zinc(II)-5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (ZnTPyP), formed at the toluene/water interface in a centrifugalliquid membrane (CLM) cell, were investigated by comparison with the microscopic CD and LD spectra of a singleinterfacial aggregate of ZnTPyP about 100 
m in length, measured by a microscope-spectropolarimeter. The interfacialZnTPyP aggregate showed two types of flat trapezoidal shapes, one had a seedlike core at an edge (type I) and anothera needlelike core at an edge (type II). The microscopic CD and LD spectra were observed by varying the angle betweenthe parallel axis of the trapezoidal aggregate and the perpendicular axis of a polarized light for LD. The plot of theCD intensity against the LD intensity for a single aggregate, observed at a given wavelength, showed a rotated ellipticalshape with a long axis through the origin, when the orientation angle was changed. From these results, it was concludedthat the apparent CD spectra observed by the CLM-CD method were mainly due to the large linear dichroism of theaggregate. Both type I and type II structures showed two transition dipole moments, parallel and perpendicular to thelong axis of the structure, but suggesting a more developed J-aggregate in type II structure. AFM measurements showedthat the interfacial ZnTPyP aggregate had a multilayer structure, in which the unit monolayer thickness was 1.58 ±0.23 nm. Finally, the orientation angle of the interfacial aggregate in the CLM cell was estimated as 41
-44 to therotating axis of the cell.
m in length, measured by a microscope-spectropolarimeter. The interfacialZnTPyP aggregate showed two types of flat trapezoidal shapes, one had a seedlike core at an edge (type I) and anothera needlelike core at an edge (type II). The microscopic CD and LD spectra were observed by varying the angle betweenthe parallel axis of the trapezoidal aggregate and the perpendicular axis of a polarized light for LD. The plot of theCD intensity against the LD intensity for a single aggregate, observed at a given wavelength, showed a rotated ellipticalshape with a long axis through the origin, when the orientation angle was changed. From these results, it was concludedthat the apparent CD spectra observed by the CLM-CD method were mainly due to the large linear dichroism of theaggregate. Both type I and type II structures showed two transition dipole moments, parallel and perpendicular to thelong axis of the structure, but suggesting a more developed J-aggregate in type II structure. AFM measurements showedthat the interfacial ZnTPyP aggregate had a multilayer structure, in which the unit monolayer thickness was 1.58 ±0.23 nm. Finally, the orientation angle of the interfacial aggregate in the CLM cell was estimated as 41-44 to therotating axis of the cell.