Dataset Information

Conjugated Porphyrin Dimers: Cooperative Effects and Electronic Communication in Supramolecular Ensembles with C₆₀.

ABSTRACT: Two new conjugated porphyrin-based systems (dimers 3 and 4) endowed with suitable crown ethers have been synthesized as receptors for a fullerene-ammonium salt derivative (1). Association constants in solution have been determined by UV-vis titration experiments in CH₂Cl₂ at room temperature. The designed hosts are able to associate up to two fullerene-based guest molecules and present association constants as high as ?5 × 10⁸ M^-1. Calculation of the allosteric cooperative factor ? for supramolecular complexes [3·1₂] and [4·1₂] showed a negative cooperative effect in both cases. The interactions accounting for the formation of the associates are based, first, on the complementary ammonium-crown ether interaction and, second, on the ?-? interactions between the porphyrin rings and the C₆₀ moieties. Theoretical calculations have evidenced a significant decrease of the electron density in the porphyrin dimers 3 and 4 upon complexation of the first C₆₀ molecule, in good agreement with the negative cooperativity found in these systems. This negative effect is partially compensated by the stabilizing C₆₀-C₆₀ interactions that take place in the more stable syn-disposition of [4·1₂].

SUBMITTER: Moreira L

PROVIDER: S-EPMC5133674 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature

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Publications

Conjugated Porphyrin Dimers: Cooperative Effects and Electronic Communication in Supramolecular Ensembles with C60.

Moreira Luis L Calbo Joaquín J Aragó Juan J Illescas Beatriz M BM Nierengarten Iwona I Delavaux-Nicot Béatrice B Ortí Enrique E Martín Nazario N Nierengarten Jean-François JF

Journal of the American Chemical Society 20160929 47

Two new conjugated porphyrin-based systems (dimers 3 and 4) endowed with suitable crown ethers have been synthesized as receptors for a fullerene-ammonium salt derivative (1). Association constants in solution have been determined by UV-vis titration experiments in CH2Cl2 at room temperature. The designed hosts are able to associate up to two fullerene-based guest molecules and present association constants as high as ∼5 × 108 M-1. Calculation of the a ...[more]

PMID: 27640915

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Project description:There are a number of lipophilic cations that can be chosen; the triphenylphosphonium (TPP) ion is particularly unique for mitochondrion targeting, mainly due to its simplicity in structure and ease to be linked to the target molecules. In this work, mitochondrion-targeted AB3-type novel phthalocyanine and porphyrin photosensitizers (PSs) were synthesized and their photophysical photochemical properties were defined. Fluorescence quantum yields (ΦF) are 0.009, 0.14, 0.13, and 0.13, and the singlet-oxygen quantum yields (ΦΔ) are 0.27, 0.75, 0.57, and 0.58 for LuPcPox(OAc), AB 3 TPP-Pc, AB 3 TPP-Por-C4, and AB 3 TPP-Por-C6, respectively. To evaluate the photodynamic efficacy of the TPP-conjugated PS cell viabilities of A549 and BEAS-2B lung cells were comparatively measured and IC-50 values were determined. AB 3 TPP-Por-C4, AB 3 TPP-Por-C6, and AB 3 TPP-Pc compounds compared to the reference molecules ZnPc and H 2 TPP were found to be highly cytotoxic (sub-micromolar concentration) under the light. LuPcPox(OAc) is the most effective molecule regarding cell killing (the activity). The cell killing of the TPP-conjugated porphyrin derivatives exhibits a similar response compared to LuPcPox(OAc) when the light absorbing factor of the PS is normalized at 660 nm: TPP-conjugated porphyrins absorb less light (lower extinction coefficient) but produce more radical species (higher singlet-oxygen quantum yield) and therefore effectively kill the cells. The singlet oxygen-producing capacity of AB 3 TPP-Pc is almost 3 times higher compared to LuPcPox(OAc) and 50% more efficient with respect to ZnPc, suggesting that TPP-conjugated phthalocyanine may serve as a good photosensitizer for photodynamic therapy (PDT). The high singlet oxygen generation capacity of these novel TPP-conjugated porphyrin and phthalocyanine PS suggests that they might be useful for PDT requiring lower photosensitizer concentration and reduced energy deposited through less light exposure.

Dataset Information

Conjugated Porphyrin Dimers: Cooperative Effects and Electronic Communication in Supramolecular Ensembles with C₆₀.

Publications

Conjugated Porphyrin Dimers: Cooperative Effects and Electronic Communication in Supramolecular Ensembles with C<sub>60</sub>.

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