Kinetic Investigation on Tetrakis(4-Sulfonatophenyl)Porphyrin J-Aggregates Formation Catalyzed by Cationic Metallo-Porphyrins

Under mild acidic conditions, various metal derivatives of tetrakis(4-N-methylpyridinium)porphyrin (gold(III), AuT4; cobalt(III), CoT4; manganese(III), MnT4 and zinc(II), ZnT4) catalytically promote the supramolecular assembling process of the diacid 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (H2TPPS4) into J-aggregates. The aggregation kinetics have been treated according to a well-established model that involves the initial formation of a critical nucleus containing m porphyrin units, followed by autocatalytic growth, in which the rate evolves as a power of time. An analysis of the extinction time traces allows to obtain the rate constants for the auto-catalyzed pathway, kc, and the number of porphyrins involved in the initial seeding. The aggregation kinetics have been investigated at fixed H2TPPS4 concentration as a function of the added metal derivatives MT4. The derived rate constants, kc, obey a rate law that is first order in [MT4] and depend on the specific nature of the catalyst in the order AuT4 > CoT4 > MnT4 > ZnT4. Both resonance light scattering (RLS) intensity and extinction in the aggregated samples increase on increasing [MT4]. With the exception of AuT4, the final aggregated samples obtained at the highest catalyst concentration exhibit a negative Cotton effect in the J-band region, evidencing the occurrence of spontaneous symmetry breaking. The role of the nature of the metal derivative in terms of overall charge and presence of axial groups will be discussed.

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

International Journal of Molecular Sciences ◽

10.3390/ijms21114001 ◽

2020 ◽

Vol 21 (11) ◽

pp. 4001 ◽

Cited By ~ 2

Author(s):

Ilaria Giuseppina Occhiuto ◽

Maria Angela Castriciano ◽

Mariachiara Trapani ◽

Roberto Zagami ◽

Andrea Romeo ◽

...

Keyword(s):

Ionic Strength ◽

Supramolecular Assembly ◽

Structural Features ◽

Cotton Effect ◽

Resonance Light Scattering ◽

Water Soluble ◽

Complete Analysis ◽

Coupling Mechanism ◽

Extinction Time ◽

J Aggregates

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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The role of secondary alcoholic groups of D-galacturonan in its degradation with exo-D-galacturonanase

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19800427 ◽

1980 ◽

Vol 45 (2) ◽

pp. 427-434 ◽

Cited By ~ 4

Author(s):

Kveta Heinrichová ◽

Rudolf Kohn

Keyword(s):

Acetyl Derivative ◽

Competitive Inhibitor ◽

Hydroxyl Groups ◽

Pectic Acid ◽

Substrate Complex ◽

Enzyme Substrate ◽

The Individual ◽

Degradation Degree ◽

Derivatives Of

The effect of exo-D-galacturonanase from carrot on O-acetyl derivatives of pectic acid of variousacetylation degree was studied. Substitution of hydroxyl groups at C(2) and C(3) of D-galactopyranuronic acid units influences the initial rate of degradation, degree of degradation and its maximum rate, the differences being found also in the time of limit degradations of the individual O-acetyl derivatives. Value of the apparent Michaelis constant increases with increase of substitution and value of Vmax changes. O-Acetyl derivatives act as a competitive inhibitor of degradation of D-galacturonan. The extent of the inhibition effect depends on the degree of substitution. The only product of enzymic reaction is D-galactopyranuronic acid, what indicates that no degradation of the terminal substituted unit of O-acetyl derivative of pectic acid takes place. Substitution of hydroxyl groups influences the affinity of the enzyme towards the modified substrate. The results let us presume that hydroxyl groups at C(2) and C(3) of galacturonic unit of pectic acid are essential for formation of the enzyme-substrate complex.

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Outer-sphere interaction of (S)-asparagine and (S)-glutamine with [Co(NH3)6]3+ ion and its possible role in ligand substitution

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19872457 ◽

1987 ◽

Vol 52 (10) ◽

pp. 2457-2459

Author(s):

František Jursík

Keyword(s):

Amino Acids ◽

Transition Region ◽

Alkaline Medium ◽

Optical Activity ◽

Substitution Reaction ◽

Outer Sphere ◽

Ligand Substitution ◽

Cotton Effect ◽

Negative Cotton Effect

Optical activity of the achiral cation [Co(NH3)6]3+ is induced both by (S)-AsnONa and (S)-GlnONa, as shown by a negative Cotton effect in the 1A1g → 1T1g transition region. An outer-sphere interaction by three-point attachment of the amides can explain the fact that substitution reaction of [Co(NH3)6]3+ with the mentioned amides in an alkaline medium is unusually slow as compared with other amino acids.

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Anomalous narrowing of the shape of the structural process in derivatives of trehalose at high pressure. The role of the internal structure

Journal of Molecular Liquids ◽

10.1016/j.molliq.2021.116321 ◽

2021 ◽

pp. 116321

Author(s):

Dawid Heczko ◽

Joanna Grelska ◽

Karolina Jurkiewicz ◽

Patrycja Spychalska ◽

Anna Kasprzycka ◽

...

Keyword(s):

High Pressure ◽

Internal Structure ◽

Structural Process ◽

Derivatives Of

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The Role of H2C2O4 and Na2CO3 as Precipitating Agents on The Physichochemical Properties and Photocatalytic Activity of Bismuth Oxide

Open Chemistry ◽

10.1515/chem-2020-0013 ◽

2020 ◽

Vol 18 (1) ◽

pp. 129-137

Author(s):

Yayuk Astuti ◽

Rizka Andianingrum ◽

Abdul Haris ◽

Adi Darmawan ◽

Keyword(s):

Photocatalytic Activity ◽

Methyl Orange ◽

Physicochemical Properties ◽

Bismuth Oxide ◽

Rate Constants ◽

Degradation Rate ◽

Precipitation Method ◽

Methyl Orange Degradation ◽

Methyl Orange Dye

AbstractSynthesis of bismuth oxide synthesis through the precipitation method using H2C2O4 and Na2CO3 precipitating agents, identification of physicochemical properties and its photocatalysis activity for methyl orange degradation were conducted. The bismuth oxide synthesis was undertaken by dissolving Bi(NO3)3.5H2O in HNO3, then added precipitating agents to form precipitate. The results showed that bismuth oxide produced by H2C2O4 precipitating agent was a yellow powder containing a mixture of α-Bi2O3 (monoclinic) and β-Bi2O3 (tetragonal), porous with size of 28-85 μm. Meanwhile, the use of Na2CO3 as precipitating agent resulted in bismuth oxide consisting of α-Bi2O3 and β-Bi2O3 and Bi2O4, irregular shape without pore being 40-115 μm in size. Bismuth oxide synthesized with H2C2O4 precipitating agent showed higher photocatalytic activity compared to bismuth oxide synthesized using Na2CO3 on degrading methyl orange dye with degradation rate constants of 2.35x10-5 s-1 for H2C2O4 and 1.81x10-5 s-1 for Na2CO3.

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Deciphering the role of quantum dot size in the ultrafast charge carrier dynamics at the perovskite–quantum dot interface

Journal of Materials Chemistry C ◽

10.1039/d0tc03835k ◽

2020 ◽

Vol 8 (42) ◽

pp. 14834-14844

Author(s):

Piotr Piatkowski ◽

Sofia Masi ◽

Pavel Galar ◽

Mario Gutiérrez ◽

Thi Tuyen Ngo ◽

...

Keyword(s):

Quantum Dot ◽

Charge Carrier ◽

Rate Constants ◽

Transient Absorption ◽

Carrier Dynamics ◽

Carrier Transfer ◽

Charge Carrier Dynamics ◽

Conduction Bands

Charge-carrier transfer (CT) from the perovskite host to PbS QDs were studied using fs-transient absorption and THz techniques. The CT rate constants increase with the size of QDs due to a change in the position of valence and conduction bands in PbS QDs.

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The first nitrogen-only-bonded metal derivatives of cyclenphosphorane. Formation of cyclenPH.cntdot.MCl2 and cyclenPH.cntdot.HMCl3 (M = zinc, cadmium)

Inorganic Chemistry ◽

10.1021/ic00327a024 ◽

1990 ◽

Vol 29 (2) ◽

pp. 271-274 ◽

Cited By ~ 6

Author(s):

Dilip V. Khasnis ◽

Michael Lattman ◽

Upali Siriwardane

Keyword(s):

Zinc Cadmium ◽

Metal Derivatives ◽

Derivatives Of

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Transition metal activation of aldehydes: platinum metal derivatives of o-diphenylphosphinobenzaldehyde

Journal of the American Chemical Society ◽

10.1021/ja00498a049 ◽

1979 ◽

Vol 101 (4) ◽

pp. 1045-1047 ◽

Cited By ~ 64

Author(s):

Thomas B. Rauchfuss

Keyword(s):

Transition Metal ◽

Platinum Metal ◽

Metal Derivatives ◽

Derivatives Of

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Enzymatic synthesis and phosphorolysis of 4(2)-thioxo- and 6(5)-azapyrimidine nucleosides by E. coli nucleoside phosphorylases

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.12.254 ◽

2016 ◽

Vol 12 ◽

pp. 2588-2601 ◽

Cited By ~ 3

Author(s):

Vladimir A Stepchenko ◽

Anatoly I Miroshnikov ◽

Frank Seela ◽

Igor A Mikhailopulo

Keyword(s):

Purine Nucleoside Phosphorylase ◽

Reaction Conditions ◽

E Coli ◽

No Formation ◽

Structural Peculiarities ◽

Substrate Properties ◽

Nucleoside Phosphorylases ◽

Derivatives Of

The trans-2-deoxyribosylation of 4-thiouracil (4SUra) and 2-thiouracil (2SUra), as well as 6-azauracil, 6-azathymine and 6-aza-2-thiothymine was studied using dG and E. coli purine nucleoside phosphorylase (PNP) for the in situ generation of 2-deoxy-α-D-ribofuranose-1-phosphate (dRib-1P) followed by its coupling with the bases catalyzed by either E. coli thymidine (TP) or uridine (UP) phosphorylases. 4SUra revealed satisfactory substrate activity for UP and, unexpectedly, complete inertness for TP; no formation of 2’-deoxy-2-thiouridine (2SUd) was observed under analogous reaction conditions in the presence of UP and TP. On the contrary, 2SU, 2SUd, 4STd and 2STd are good substrates for both UP and TP; moreover, 2SU, 4STd and 2’-deoxy-5-azacytidine (Decitabine) are substrates for PNP and the phosphorolysis of the latter is reversible. Condensation of 2SUra and 5-azacytosine with dRib-1P (Ba salt) catalyzed by the accordant UP and PNP in Tris∙HCl buffer gave 2SUd and 2’-deoxy-5-azacytidine in 27% and 15% yields, respectively. 6-Azauracil and 6-azathymine showed good substrate properties for both TP and UP, whereas only TP recognizes 2-thio-6-azathymine as a substrate. 5-Phenyl and 5-tert-butyl derivatives of 6-azauracil and its 2-thioxo derivative were tested as substrates for UP and TP, and only 5-phenyl- and 5-tert-butyl-6-azauracils displayed very low substrate activity. The role of structural peculiarities and electronic properties in the substrate recognition by E. coli nucleoside phosphorylases is discussed.

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