Molecular spring washers: Raman scattering studies on Tpp J-aggregates under high pressure.

High-pressure Raman scattering studies at ambient temperature are performed on Tpp J-aggregates up to 13 GPa. It can be concluded that all the vibrational frequencies upshift linearly with increasing pressure which indicate that no obvious phase transition occurs during compression. In particular, the fact that the relative intensity of phenyl psi3 C-C in-plane stretching vibration shows monotonic enhancement with pressure future indicates that the dihedral angle between the porphyrin ring and phenyl groups decreases with increasing pressure. And all the transformation is reversible during decompression. The combined analysis of scanning election microscopy (SEM) image and the high-pressure behavior of Tpp J-aggregates makes it an ideal candidate for future potential applications as pressure-driven molecular spring washers.