Micali Norberto, Villari Valentina, Castriciano Maria Angela, Romeo Andrea, Monsù Scolaro Luigi
CNR-Istituto per i Processi Chimico-Fisici, Via La Farina 237, I-98123 Messina, Italy.
J Phys Chem B. 2006 Apr 27;110(16):8289-95. doi: 10.1021/jp060730e.
A structural change from fractal to nanorod J-aggregates of tetrakis(4-sulfonatophenyl)porphyrin has been obtained by acting on the intermolecular interaction potential. The size and shape of these self-assembled porphyrin clusters have been monitored under different experimental conditions, by means of polarized and depolarized dynamic light scattering and small and wide angle elastic light scattering. At sufficiently low porphyrin concentration and high ionic strength, the shielded repulsive potential seems to be responsible for the fractal structure of the aggregates. On the contrary, at low ionic strength (nonshielded potential) and high porphyrin concentration, these species self-assemble in a rodlike arrangement. The length of the so-formed rod-shaped aggregates decreases on increasing porphyrin concentration. Moreover, both fractals and rods display a structure-dependent optical activity induced by a chiral template.
通过作用于分子间相互作用势，已实现了四（4-磺酸基苯基）卟啉从分形聚集体到纳米棒J-聚集体的结构转变。借助偏振和去偏振动态光散射以及小角和广角弹性光散射，在不同实验条件下监测了这些自组装卟啉簇的尺寸和形状。在足够低的卟啉浓度和高离子强度下，屏蔽排斥势似乎是聚集体分形结构的原因。相反，在低离子强度（非屏蔽势）和高卟啉浓度下，这些物质以棒状排列自组装。如此形成的棒状聚集体的长度随卟啉浓度的增加而减小。此外，分形聚集体和棒状聚集体都表现出由手性模板诱导的结构依赖性光学活性。
