Chirality Enhancement of Porphyrin Supramolecular Assembly Driven by a Template Preorganization Effect

Gaeta, Massimiliano; Raciti, Domenica; Randazzo, Rosalba; Gangemi, Chiara M. A.; Raudino, Antonio; D’Urso, Alessandro; Fragalà, Maria Elena; Purrello, Roberto

doi:10.1002/anie.201806192

Cited by 34 publications

(30 citation statements)

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“…Furthermore, due to the propensity to penta-coordination of this metal ion, the presence of a fifth ligand bound to the metal center hinders the formation of aggregated species, at least at rather low ZnTPPS 4 concentrations. This strategy has proved to be successful in controlling the chirality of supramolecular assembly of this porphyrin driven by preorganization on a polypeptide template [30,62].…”

Section: Introductionmentioning

confidence: 99%

Controlling J-Aggregates Formation and Chirality Induction through Demetallation of a Zinc(II) Water Soluble Porphyrin

Occhiuto

Castriciano

Trapani

et al. 2020

IJMS

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Under acidic conditions and at high ionic strength, the zinc cation is removed from its metal complex with 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS4) thus leading to the diacid free porphyrin, that subsequently self-organize into J-aggregates. The kinetics of the demetallation step and the successive supramolecular assembly formation have been investigated as a function of pH and ionic strength (controlled by adding ZnSO4). The demetallation kinetics obey to a rate law that is first order in [ZnTPPS4] and second order in [H+], according to literature, with k2 = 5.5 ± 0.4 M−2 s−1 at 298 K (IS = 0.6 M, ZnSO4). The aggregation process has been modeled according to an autocatalytic growth, where after the formation of a starting seed containing m porphyrin units, the rate evolves as a power of time. A complete analysis of the extinction time traces at various wavelengths allows extraction of the relevant kinetic parameters, showing that a trimer or tetramer should be involved in the rate-determining step of the aggregation. The extinction spectra of the J-aggregates evidence quite broad bands, suggesting an electronic coupling mechanism different to the usual Frenkel exciton coupling. Resonance light scattering intensity in the aggregated samples increases with increasing both [H+] and [ZnSO4]. Symmetry breaking occurs in these samples and the J-aggregates show circular dichroism spectra with unusual bands. The asymmetry g-factor decreases in its absolute value with increasing the catalytic rate kc, nulling and eventually switching the Cotton effect from negative to positive. Some inferences on the role exerted by zinc cations on the kinetics and structural features of these nanostructures have been discussed.

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Section: Introductionmentioning

confidence: 99%

Controlling J-Aggregates Formation and Chirality Induction through Demetallation of a Zinc(II) Water Soluble Porphyrin

Occhiuto

Castriciano

Trapani

et al. 2020

IJMS

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“…[14][15][16] Nevertheless, porphyrin aggregates formed in aqueous media also exhibit intense ICD signals. [17][18][19][20][21][22][23][24] Chiral macrocycles, cyclohexanohemicucurbit[n]urils (cycHC [6] and cycHC [8], see Fig. 1A), have complementary dimensions with porphyrins, with their height being close to a nanometer.…”

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confidence: 99%

Supramolecular chirogenesis in zinc porphyrins by enantiopure hemicucurbit[n]urils (n = 6, 8)

et al. 2019

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“…[2] Rational molecular design allows chiral molecules with enantiomeric central atoms or axial chirality, or even some achiral molecules, to form asymmetric stacking modes by intermolecular interactions of the buildingb locks. There have been severals trategies to establisha rtificial supramolecular chirality in asymmetric stacking modes,s uch as hydrogen bonding, [3] p-p stacking, [4] templatem ethods, [5] and the "sergeants-and-soldiers" principle [6] in soft materials, such as gelators [7] or liquid-crystal media. [8] According to current research, supramolecular chirality is mainly inducedb ythermodynamic factorsa nd is at emporary equilibriumt hat depends on variouse ffects.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Modulation of Supramolecular Chirality Driven by Factors from Internal to External Levels

Yue

Zhu

2019

Chemistry An Asian Journal

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Supramolecular chirality, generated by the asymmetric assembly of chiral or achiral molecules, has attracted intense study owing to its potential to offer insights into natural biological structures and its crucial roles in advanced materials. The optical activity and stacking pathway of building molecules both greatly determine the chirality of the whole supramolecular structure. The flexibility of supramolecular structures makes their chirality easy to modulate through abundant means. Adjustment of the molecular structure or packing mode, or external stimuli that act like a finger gently pushing toy bricks, can greatly change the chirality of supramolecular assemblies. The dynamic regulation of chiral nanostructures on the intramolecular, intermolecular, and external levels could be regarded as the modulatory essence in numerous strategies, however, this perspective is ignored in most reviews in the literature. Herein, therefore, we focus on the ingenious dynamic modulation of chiral nanostructures by these factors. Through dynamic modulation with changes in chiroptical spectroscopy and electron microscopy, the mechanism of formation of supramolecular chirality is also elaborated.

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Chirality Enhancement of Porphyrin Supramolecular Assembly Driven by a Template Preorganization Effect

Cited by 34 publications

References 50 publications

Controlling J-Aggregates Formation and Chirality Induction through Demetallation of a Zinc(II) Water Soluble Porphyrin

Controlling J-Aggregates Formation and Chirality Induction through Demetallation of a Zinc(II) Water Soluble Porphyrin

Supramolecular chirogenesis in zinc porphyrins by enantiopure hemicucurbit[n]urils (n = 6, 8)

Dynamic Modulation of Supramolecular Chirality Driven by Factors from Internal to External Levels

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