Role of Cobalt(III) Cationic Complexes in the Self-Assembling Process of a Water Soluble Porphyrin

Under moderate acidic conditions, the cationic (+3) complexes ions tris(1,10-phenanthroline)cobalt(III), [Co(phen)3]3+, and hexamminecobalt(III), [Co(NH3)6]3+, efficiently promote the self-assembling process of the diacid 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (H2TPPS4) into J-aggregates. The growth kinetics have been analyzed according to a well-established autocatalytic model, in which the rate determining step is the initial formation of a nucleus containing m porphyrin units (in the range 2–3), followed by a stage whose rate constant kc evolves as a power of time. The observed catalytic rate constants and the extent of J-aggregation increase on increasing the metal complex concentration, with the phen complex being the less active. The UV/Vis extinction spectra display quite broad envelops at the J-band, especially for the amino-complex, suggesting that electronic dipolar coupling between chromophores is operative in these species. The occurrence of spontaneous symmetry breaking has been revealed by circular dichroism and the measured dissymmetry g-factor decreases on increasing the aggregation rates. The role of these metal complexes on the growth and stabilization of porphyrin nano-assemblies is discussed in terms of the different degree of hydrophilicity and hydrogen bonding ability of the ligands present in the coordination sphere around the metal center.

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A Labile Metallo-Porphyrin as Tool to Control J-Aggregates Chiroptical Properties

10.32545/encyclopedia202006.0019.v16 ◽

2020 ◽

Author(s):

Luigi Monsù Scolaro ◽

Ilaria Occhiuto ◽

Mariachiara Trapani ◽

ROBERTO ZAGAMI ◽

Andrea Romeo ◽

...

Keyword(s):

Dipolar Coupling ◽

Initial Conditions ◽

Coupling Mechanism ◽

Precise Control ◽

Rate Determining Step ◽

Initial Nucleus ◽

Acidic Conditions ◽

J Aggregates ◽

Kinetics Of ◽

Autocatalytic Growth

The zinc(II) metal derivative of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS4) is quite labile and readily demetallates under acidic conditions, affording the parent diacid porphyrin in a monomeric form. The rate of this process is first order on [ZnTPPS4] and second order on [H+], allowing a precise control of the monomer release in solution. Under high ionic strength, this latter species is able to self-assemble into J-aggregates, whose kinetics of growth are largely modulated by pH. The aggregation kinetics have been treated according to a well-established model, in which the formation of an initial nucleus is the rate determining step preceding the autocatalytic growth of the whole assembly. The extinction spectra of the aggregates suggest the occurrence of a dipolar coupling mechanism very similar to that operating in metal nanoparticles. Spontaneous symmetry breaking takes place in these aggregates as evidenced by unusual circular dichroism spectra. The intensity and sign of the effect is controlled by the aggregation rate and therefore can be tuned through a proper choice of initial conditions.

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Effects of the Mixing Protocol on the Self-Assembling Process of Water Soluble Porphyrins

International Journal of Molecular Sciences ◽

10.3390/ijms22020797 ◽

2021 ◽

Vol 22 (2) ◽

pp. 797

Author(s):

Maria Angela Castriciano ◽

Sergio Cardillo ◽

Roberto Zagami ◽

Mariachiara Trapani ◽

Andrea Romeo ◽

...

Keyword(s):

Alternative Pathway ◽

Ion Pairs ◽

Resonance Light Scattering ◽

Water Soluble ◽

Self Assembling ◽

Vis Spectroscopy ◽

Acidic Conditions ◽

J Aggregates ◽

Kinetics Of ◽

Tartrate Anion

The hierarchical self-assembling kinetics of the porphyrin 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (H2TPPS44−) into J-aggregates at high ionic strength under acidic conditions and eventually in the presence of an added chiral templating agent (tartrate) were investigated through UV/Vis spectroscopy, resonance light scattering, and circular dichroism (CD). The effect of changing the mixing order of the various components in the solution on the kinetic parameters and the expression of chirality on the final J-aggregates was evaluated. In this latter case, only when the chiral tartrate anion is premixed with the porphyrin, the resulting nano-architectures exhibit CD spectra that reflect the handedness of the chiral inducer. We discuss a general mechanistic scheme, with the involvement of ion pairs or dimers that offer an alternative pathway to the aggregation process.

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Directive Effect of Chain Length in Modulating Peptide Nano-assemblies

Protein and Peptide Letters ◽

10.2174/0929866527666200224114627 ◽

2020 ◽

Vol 27 (9) ◽

pp. 923-929

Author(s):

Gaurav Pandey ◽

Prem Prakash Das ◽

Vibin Ramakrishnan

Keyword(s):

Electron Microscopy ◽

Amino Acids ◽

Light Scattering ◽

Chain Length ◽

Self Assembly ◽

The Self ◽

Ionic Charge ◽

Self Assembling ◽

Biophysical Techniques

Background: RADA-4 (Ac-RADARADARADARADA-NH2) is the most extensively studied and marketed self-assembling peptide, forming hydrogel, used to create defined threedimensional microenvironments for cell culture applications. Objectives: In this work, we use various biophysical techniques to investigate the length dependency of RADA aggregation and assembly. Methods: We synthesized a series of RADA-N peptides, N ranging from 1 to 4, resulting in four peptides having 4, 8, 12, and 16 amino acids in their sequence. Through a combination of various biophysical methods including thioflavin T fluorescence assay, static right angle light scattering assay, Dynamic Light Scattering (DLS), electron microscopy, CD, and IR spectroscopy, we have examined the role of chain-length on the self-assembly of RADA peptide. Results: Our observations show that the aggregation of ionic, charge-complementary RADA motifcontaining peptides is length-dependent, with N less than 3 are not forming spontaneous selfassemblies. Conclusion: The six biophysical experiments discussed in this paper validate the significance of chain-length on the epitaxial growth of RADA peptide self-assembly.

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Case history of porphyrin J-aggregates: a personal point of view

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424609000632 ◽

2009 ◽

Vol 13 (04n05) ◽

pp. 461-470 ◽

Cited By ~ 9

Author(s):

Joaquim Crusats ◽

Zoubir El-Hachemi ◽

Carlos Escudero ◽

Josep M. Ribó

Keyword(s):

Supramolecular Chemistry ◽

Self Assembly ◽

Building Blocks ◽

Point Of View ◽

Water Soluble ◽

The Self ◽

Molecular Building Blocks ◽

History Of ◽

J Aggregates ◽

The University

The formation and structure of the title aggregates are paradigms of the self-assembly of amphiphilic molecular building blocks in supramolecular chemistry. This review summarizes the research in the University of Barcelona on the homoassociation of the water soluble meso 4-sulfonatophenyl-and phenyl substituted porphyrins.

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Spectroscopic and kinetic investigations on porphyrin J-aggregates induced by polyamines

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424610002586 ◽

2010 ◽

Vol 14 (08) ◽

pp. 713-721 ◽

Cited By ~ 12

Author(s):

Andrea Romeo ◽

Maria Angela Castriciano ◽

Luigi Monsù Scolaro

Keyword(s):

Early Stage ◽

Model System ◽

Kinetic Investigation ◽

Aggregation Process ◽

Kinetic Behavior ◽

Rate Determining Step ◽

Mesoscopic Structure ◽

Acidic Conditions ◽

J Aggregates ◽

Kinetic Investigations

A non-covalent supramolecular approach to build up mesoscopic fractal J-aggregates of meso-tetrakis(4-sulfonatophenyl)porphyrin by using different polyamines under mild acidic conditions is reported. Spermine-induced J-aggregates have been treated as a model system for a kinetic investigation. The kinetic analysis has been performed through two non-conventional approaches as function of a different reagent mixing protocol. In particular, an autocatalytic pathway in which the formation of aggregation nuclei is the rate-determining step is found when porphyrin is added to the reaction mixture as first reagent. In order to gain information on this early stage, a kinetic investigation has been carried out as function of different parameters, such as pH, and both spermine and porphyrin concentration. The nucleation becomes particularly evident when polyamines with fewer than three protonable nitrogen atoms are used. In these cases, a sort of "YES/NO" effect for the aggregation process has been found as a function of the reagent mixing order protocol. Most importantly, the observed kinetic behavior strongly affects the mesoscopic structure of the final aggregates.

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Influence of Magnetic Micelles on Assembly and Deposition of Porphyrin J-Aggregates

Nanomaterials ◽

10.3390/nano10020187 ◽

2020 ◽

Vol 10 (2) ◽

pp. 187 ◽

Cited By ~ 4

Author(s):

Maria Angela Castriciano ◽

Mariachiara Trapani ◽

Andrea Romeo ◽

Nicoletta Depalo ◽

Federica Rizzi ◽

...

Keyword(s):

Water Solubility ◽

Superparamagnetic Iron Oxide ◽

Linear Dichroism ◽

Water Soluble ◽

Hydrophobic Core ◽

Force Microscopy ◽

Atomic Force ◽

Acidic Conditions ◽

J Aggregates ◽

High Degree

Clusters of superparamagnetic iron oxide nanoparticles (SPIONs) have been incorporated into the hydrophobic core of polyethylene glycol (PEG)-modified phospholipid micelles. Two different PEG-phospholipids have been selected to guarantee water solubility and provide an external corona, bearing neutral (SPIONs@PEG-micelles) or positively charged amino groups (SPIONs@NH2-PEG-micelles). Under acidic conditions and with specific mixing protocols (porphyrin first, PF, or porphyrin last, PL), the water-soluble 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin (TPPS) forms chiral J-aggregates, and in the presence of the two different types of magnetic micelles, an increase of the aggregation rates has been generally observed. In the case of the neutral SPIONs@PEG-micelles, PL protocol affords a stable nanosystem, whereas PF protocol is effective with the charged SPIONs@NH2-PEG-micelles. In both cases, chiral J-aggregates embedded into the magnetic micelles (TPPS@SPIONs@micelles) have been characterized in solution through UV/vis absorption and circular/linear dichroism. An external magnetic field allows depositing films of the TPPS@SPIONs@micelles that retain their chiroptical properties and exhibit a high degree of alignment, which is also confirmed by atomic force microscopy.

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Preliminary Research on the Interaction between a Novel Designed Self-Assembling Peptide with Half-Sequence Ionic Complement and the Natural Product Psoralen

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.550-553.1580 ◽

2012 ◽

Vol 550-553 ◽

pp. 1580-1585

Author(s):

Li Li Tang ◽

Fu Yi Guan ◽

Dao Hang He

Keyword(s):

Natural Product ◽

Pure Water ◽

Water Soluble ◽

The Self ◽

Peptide Sequence ◽

Force Microscopy ◽

Self Assembling ◽

Hydrophobic Compounds ◽

Atomic Force ◽

Preliminary Research

This paper describes a new kind of 9-residue half-sequence ionic-complementary peptide P-X7-P, which can spontaneously self-assemble into well-ordered and long interconnected nanofibrilar network structure in pure water, and can be used as a hydrophobic compounds carrier. Psoralen, a natural product, is slight water soluble but has various treatments in medicine. In order to fully understand the interaction between the self-assembling peptide and psoralen,the nanostructures formed by two of them were characterized by atomic force microscopy (AFM), field-emission scanning electron microscopy (FE-SEM). This work provides insights on the interaction between the amphiphilic self-assembling peptide and psoralen that are useful for the bottom up development of peptide sequence for local natural product drug delivery applications.

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