Pyrene-to-porphyrin excited singlet energy transfer in LBL-deposited LDH nanosheets

Abstract

Nano-ordered hybrid films of layered double hydroxide (LDH) nanosheets and two types of anionic dye molecules, i.e. tetrakis(4-carboxyphenyl)porphyrin (TCPP) and 1,3,6,8-pyrenetetrasulfonic acid (PTSA), were prepared by a layer-by-layer deposition (LBL) method. Photo-induced energy transfers (PET) between the PTSA and TCPP layers were investigated for two differently stacked structures of the TCPP/LDH/PTSA hybrid films, i.e. (a) PTSA/LDH multilayers independently stacked on the TCPP/LDH multilayers to form (TCPP/LDH)n/(PTSA/LDH)n and (b) TCPP/LDH and PTSA/LDH monolayers deposited alternately to form [(TCPP/LDH)/(PTSA/LDH)]n hybrid films, which were both prepared by varying the successive and alternate stacking of the (TCPP/LDH) and (PTSA/LDH) unit layers. A Foerster type resonance energy transfer is observed in the present hybrid films, where the efficiency of PET was strongly affected by changing the distance between the TCPP and PTSA molecules in the (TCPP/LDH)3/(PSS/LDH)m/(PTSA/LDH)3 hybrid films ( m = 1−10) obtained by the insertion of the photochemically inert poly(styrenesulfonic acid) (PSS) and LDH hybrid layers, i.e. the insertion of (PSS/LDH)m between the (TCPP/LDH)3 and (PTSA/LDH)3 layers.