Two-Photon Absorption Enhancement of Polymer-Templated Porphyrin-Based J-Aggregates

Abstract

Supramolecular structures based on organized assemblies of macrocyclic chromophores, particularly porphyrin-based dyes, have attracted widespread interest as components of molecular devices with potential applications in molecular electronics, artificial light harvesting, and pharmacology. We report the formation of J-aggregates of two porphyrin-based dyes, 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TSPP, 4) and an amino tris-sulfonate analog (5) in water using a functionalized norbornene-based homopolymer, synthesized by ring opening metathesis polymerization (ROMP). Ionic interactions of the cationic side chains (ammonium groups) of the polymer under acidic conditions with the negatively charged sulfonate groups of the porphyrins facilitated polymer template enhanced J-aggregation of the porphyrin dyes. J-aggregation behavior was investigated photophysically by UV-vis absorption along with steady-state and time-resolved fluorescence studies. Two-photon absorption (2PA) was enhanced by about an order of magnitude for the J-aggregated TSPP relative to its free base. Significantly, the 2PA cross section of the polymer-templated TSPP J-aggregate was up to three times higher than the J-aggregated TSPP in the absence of the polymer template while the 2PA cross section for polymer-templated J-aggregates of 5 increased substantially, up to ca. 10,000 GM, suggesting a prominent role of polymer-templating to facilitate porphyrin aggregation and greatly enhance nonlinear absorption.

Design and Properties of Porphyrin‐based Singlet Oxygen Generator

“…demonstrated the formation of an ionic liquid (IL)‐assisted zinc octaethylporphyrin (ZnOEP) nanoaggregate‐nickel phthalocyanine (NiPc) conjugate 11 , where NiPc molecules, bearing negative charges on the sulfonated group, were attached to the positively charged surface of a ZnOEP nanoaggregate via electrostatic interaction (Figure 12). 50 H‐aggregation of porphyrin was observed during nanoaggregate formation in the presence of the IL due to intermolecular π‐π/hydrophobic interactions among the porphyrins 51. Photoinduced singlet oxygen generation was directly investigated using the phosphorous spectra in the NIR region.…”

Synthesis of disulfide-based biodegradable bridged silsesquioxane nanoparticles for two-photon imaging and therapy of cancer cells

“…35,36 Concerning DISP NPs, the surprising two-photon sensitivity of the DISP NPs arose from the POR J aggregates, as reported in the literature. 37 The disulfide framework is thus well-suited for the design of biodegradable nanomedical tools for two-photon imaging and therapy.…”

Conformation Control of a Conjugated Polymer through Complexation with Bile Acids Generates Its Novel Spectral and Morphological Properties

“…To design such functional materials, cofusion of the polymeric compound as a template axle with the molecular assembly as peripheral decoration compounds seems to be the most potential approach. [4][5][6][7][8] In fact, we previously designed several polymer-based molecular organization systems, in which conjugated polymers or carbon nanotubes are finely oriented with the aid of the self-assembling nature of low molecular-weight compounds. [9][10][11][12][13] For example, when nucleosides were organized through the boronic acid-diol interaction on the boronic-acid-appended poly(L-lysine) chain, the resultant nucleotide assembly could be arranged by a pH-induced conformational change in the poly(Llysine) chain.…”