Supramolecular Chirality and Chiral Inversion of Tetraphenylsulfonato Porphyrin Assemblies on Optically Active Polylysine

Abstract

The self-assembly and induced supramolecular chirality of a dianionic meso-tetraphenylsulfonato porphyrin (TPPS) on the optically active polylysine has been investigated. Our research has confirmed that in the presence of poly(l-lysine) (PLL) or poly(d-lysine) (PDL), TPPS could form both H and J aggregates and the exciton type Cotton effect was induced in the corresponding absorption bands of H and J-aggregates. We have further revealed that the induced chirality of the H-band always followed the chirality of PLL or PDL, while the sign of the exciton couplet in the J-band could be the same as or opposite to that of the H-band depending on the mixing sequence and the ratio of PLL or PDL to TPPS (P/T ratio). At a P/T ratio less than 4, both the J and H aggregates showed the same symbolic CD signal. At a P/T ratio larger than 4, the opposite sign of the exciton couplet was observed for H and J-bands when TPPS was added into PLL, while the same sign was obtained when PLL was added into TPPS. Interestingly, the J-band with the same sign as that of the H-band can be inverted into the opposite sign under heating. A mechanism relating to the dynamic and thermodynamic formation of the chiral aggregates in the presence of PLL or PDL was proposed.

Chirality and energy transfer amplified circularly polarized luminescence in composite nanohelix

“…In this case, although the handedness of the nanohelix did not change, the packing of the acceptor is in the opposite direction of the nanohelix, therefore, we observed inversion of the supramolecular chirality localized on the BPEA. It is interesting that the guest (acceptor) molecules can carry on either the same or the opposite chiral packing against the host (donor) chiral matrices, which have been widely reported in supramolecular-assembled chiral systems5565758. This phenomenon has been explained to the different molecular packing between host chiral donors and guest achiral acceptors according to the theory of exciton-coupled circular dichroism59.…”

Supramolecular Chirality in Self-Assembled Systems

“…188 Through simple adjustment of the mixing sequences of TPPS with poly(lysine), opposite CD signals from TPPS J aggregation were obtained. When PLL was dropped into the TPPS solution (process I), a negative CD signal was observed.…”

ZnTPPS demetalation: Role of polyelectrolytes on aggregation after protonation in acid

“…At pH = 3 we can assume that PLL acts as proton sink, thus competing with protonation of ZnTPPS that binds to polymeric chain as a pending molecule, thus maintaining its monomeric form. By lowering pH, protonation occurs and, as discussed by other authors [22], protonated porphyrins in proximity of PLL chains rearrange along the groove of the polyelectrolyte in a head-to-tail conformation, thus forming J-aggregates. PLL, in fact, is positively charged at pH = 1.5 and strongly attracts anionic porphyrins.…”

“…Notably, at pH = 1.5 an instantaneous protonation occurs: in fact, the initial absorbance value at 421 nm is significantly lower (about half) than that observed at higher pH levels, while a component at 434 nm is immediately observed in these conditions. However, even after 6 hours, self-aggregation of formed diacid species is not observable, as for the case of free base H 2 TPPS 4-at the same pH [10,22].…”