Spectroscopic detection of chiral aggregation at liquid-liquid interfaces

Potential-Induced Aggregation of Anionic Porphyrins at Liquid|Liquid Interfaces

“…The J-aggregates retain the structure in a suitable slipped face-to-face stacking. , The monomeric H 4 TPPS 2– shows the Soret and Q bands at around 434 and 645 nm in aqueous solutions, respectively, whereas the J-aggregates of H 4 TPPS 2– exhibit sharp and intense absorption bands at around 491 and 707 nm (Figure S1a). − In the PM-TIRF measurement, the Δ F p–s signals from the interfacial species are associated with the orientations of the porphyrin ring of monomers or the long axis of aggregates. , The fluorescence maximum wavelengths of the PM-TIRF spectra are summarized in Table . In Figure a, the PM-TIRF spectra with a negative sign (Δ F p–s < 0) exhibited features similar to those of the fluorescence spectra of the diacid form in aqueous solutions, indicating that the H 4 TPPS 2– monomers were adsorbed with relatively lying orientation (54.7° < θ ≤ 90°) and their adsorption state was almost consistent with that in the bulk aqueous phase.…”

“…from the interfacial species should be associated with the orientations of the porphyrin ring of monomers or the long axis of aggregates. 50,51 The fluorescence maximum wavelengths of the PM-TIRF spectra are summarized in Table 1. In Figure 3a, the PM-TIRF spectra with a negative sign ( also suggests that the long axis of the J-aggregates was lying nearly parallel to (Figure 4).…”

Linear Dichroism of Zn(II)−Tetrapyridylporphine Aggregates Formed at the Toluene/Water Interface

“…At the liquid−liquid interface, it is expected that a molecular aggregate, which is not formed in the bulk phase, can be formed easily, because the interfacial concentration of a surface active monomer becomes much higher than that in the bulk phase. The adsorption and aggregation behaviors of molecules were investigated by means of various methods. − Recently, we investigated the chiral aggregates of porphyrins and phthalocyanine formed at liquid/liquid interfaces by circular dichroism measurements combined with a centrifugal liquid membrane (CLM) technique or second-harmonic generation spectrometry (SHG). − It has been suggested by a CLM-CD measurement that the interfacial self-aggregate of zinc(II)−5,10,15,20-tetra(4-pyridyl)-21 H ,23 H -porphine (ZnTPyP) shows an apparent circular dichroism . In the present study, the cause of the apparent circular dichroism of ZnTPyP aggregates reported previously 41 was investigated in detail from the comparison between the CD and LD spectra measured by the CLM method and those measured by a new microscopic spectropolarimeter technique.…”

“…[33][34][35][36][37] Recently, we investigated the chiral aggregates of porphyrins and phthalocyanine formed at liquid/liquid interfaces by circular dichroism measurements combined with a centrifugal liquid membrane (CLM) technique or second-harmonic generation spectrometry (SHG). [38][39][40] It has been suggested by a CLM-CD measurement that the interfacial self-aggregate of zinc(II)-5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (ZnTPyP) shows an apparent circular dichroism. 41 In the present study, the cause of the apparent circular dichroism of ZnTPyP aggregates reported previously 41 was investigated in detail from the comparison between the CD and LD spectra measured by the CLM method and those measured by a new microscopic spectropolarimeter technique.…”