scholarly journals Fluorescence visualization of the molecular assembly processes during solvent evaporation via aggregation-induced emission in a cyanostilbene derivative

CrystEngComm ◽  
2014 ◽  
Vol 16 (42) ◽  
pp. 9779-9782 ◽  
Author(s):  
Fuyuki Ito ◽  
Jun-ichi Fujimori
Keyword(s):  
Molecular Assembly ◽  
Solvent Evaporation ◽  
Crystal Formation ◽  
Formation Processes ◽  
Nucleation Process ◽  
Aggregation Induced Emission ◽  
Rate Determining Step ◽  
J Aggregates

We applied AIEE to the visualization of crystal formation processes. We found that J-aggregates act as precursors for crystal nuclei, and that the growth from J-aggregates to crystal nuclei is the rate-determining step in the nucleation process.

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

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.

scholarly journals AIE phenomena of a cyanostilbene derivative as a probe of molecular assembly processes

2017 ◽  
Vol 196 ◽  
pp. 231-243 ◽  
Author(s):  
Fuyuki Ito ◽  
Jun-ichi Fujimori ◽  
Narumi Oka ◽  
Michel Sliwa ◽  
Cyril Ruckebusch ◽  
...  
Keyword(s):  
Fluorescence Spectra ◽  
Volume Fraction ◽  
Binary Solution ◽  
Molecular Assembly ◽  
Multivariate Curve Resolution ◽  
Crystal Formation ◽  
Curve Resolution ◽  
Solvent Water ◽  
The Poor ◽  
Poor Solvent

The initial processes of the crystallization of a solute molecule, 1-cyano-trans-1,2-bis-(4′-methylbiphenyl)-ethylene (CN-MBE) in binary solution (water and acetone), were investigated by means of fluorescence spectroscopy as well as scanning electron microscopy (SEM). With an increase in the volume fraction (Vw) of the poor solvent (water) in the solution, a drastic change in the fluorescence spectra and intensity of CN-MBE was observed. This change was attributed to aggregation induced emission (AIE). By analyzing the evolution of AIE by multivariate curve resolution-alternating least squares (MCR-ALS), it was revealed that four main species appeared in the solution depending on the Vw values. On the basis of molecular exciton theory, we assigned these four emissive states to the monomer, H-dimer, J-dimer, and H-aggregates. Interestingly, the J-dimer state was observed only in a Vw range of 40% to 50%, just before the formation of the aggregate. This result suggests that the J-dimer plays an important role as the precursor for larger aggregates leading to crystal formation. By integrating the present results with previous work on the crystallization of CN-MBA through solvent evaporation, we discussed the dynamics of the crystallization from the viewpoint of the sequence of molecular species appearing in the aggregation in solution.

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

2020 ◽  
Vol 22 (1) ◽  
pp. 39
Author(s):  
Nadia Manganaro ◽  
Roberto Zagami ◽  
Mariachiara Trapani ◽  
Maria Angela Castriciano ◽  
Andrea Romeo ◽  
...  
Keyword(s):  
Dipolar Coupling ◽  
Water Soluble ◽  
The Self ◽  
Rate Determining Step ◽  
Self Assembling ◽  
Acidic Conditions ◽  
J Aggregates ◽  
Water Soluble Porphyrin ◽  
Amino Complex

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.

scholarly journals Review: Effect of Different Methods on the Multicomponents Crystal Formation from Medicinal Natural Ingredient Compounds

2021 ◽  
Vol 6 (5) ◽  
pp. 32-39
Author(s):  
Eldya Nurismi ◽  
Henni Rosaini ◽  
dan Maria Dona Octavia
Keyword(s):  
Dissolution Rate ◽  
Classification System ◽  
Solvent Evaporation ◽  
Biopharmaceutics Classification System ◽  
Crystal Formation ◽  
High Permeability ◽  
Dissolution Rates ◽  
Solubility In Water ◽  
Low Solubility ◽  
Biopharmaceutics Classification

Solubility is an important parameter for the bioavailability of drugs that are difficult to dissolve. Natural compounds that are included in class II in the Biopharmaceutics Classification System (BCS) are Apigenin, Quercetin, Genistein, Curcumin, and Piperin. These drugs have low solubility in water and high permeability so that they affect the dissolution rate and as well as their bioavailability, to increase the solubility they are made with multicomponent crystals. This review aims to provide information on the method of making crystal multicomponent to increase the solubility and dissolution rate of BCS II drugs. Several methods that can be used in multicomponent are solvent drop grinding, solvent evaporation, assisted grinding, and slurry. The results showed that multicomponent crystals using several methods could increase the solubility and dissolution rates.

scholarly journals A study of the initial stages of the electrochemical deposition of thallium on copper, Part IV. The potential step results: Underpotential deposition on (111), (110) and (100) oriented copper single c

2005 ◽  
Vol 3 (2) ◽  
pp. 157-168 ◽  
Author(s):  
Jovan Jovicevic ◽  
Alan Bewick
Keyword(s):  
Single Crystal ◽  
Bulk Diffusion ◽  
Underpotential Deposition ◽  
Crystal Formation ◽  
Formation Processes ◽  
Growth Step ◽  
Current Time ◽  
Single Crystal Surfaces ◽  
Potential Step ◽  
Response Characteristics

The underpotential deposition and dissolution of thallium onto carefully chemically polished single crystal copper (111), (110) and (100) electrode surfaces from acetate, sulphate and perchlorate solutions have been investigated using single and double potential step techniques. It appeared that the different anions used did not change the current-time response characteristics significantly. Current-time responses to the potential steps applied strongly resemble those observed in the case of thallium underpotential deposition on silver single crystals [1]. The characteristics of i-t transients obtained by single potential step suggest very fast 2D crystal growth processes taking place. Sharp linear voltammetry peaks, which are observed for both thallium and lead deposition on Cu(111) [3,8] and on Ag(111) [1,3], probably always indicate nucleative phase formation processes but the rate of the lattice growth step will vary from system to system. Comparison of the obtained results with those for lead underpotential deposition [8-13] on Cu(111), (110) and (100) suggests that, in the present case, the rate of the 2D lattice building process for both thallium underpotential monolayers formed on three copper single crystal surfaces examined is so fast that it becomes controlled by diffusive processes; this will probably be surface diffusion [24,25] initially and, at longer times planar bulk diffusion. Double pulse experiments did not help significantly in attempts to obtain i-t transients capable of providing data suitable for showing conclusively the occurrence of 2D crystal formation processes. A similar situation occurred also with silver substrates [1].

scholarly journals Tubular and lamellar hydrogen-bonding molecular assemblies of isophthalic acid derivatives bearing a –CONHCnH2n+1 chain

RSC Advances ◽  
2018 ◽  
Vol 8 (39) ◽  
pp. 22250-22258 ◽  
Author(s):  
Chao Lv ◽  
Takashi Takeda ◽  
Norihisa Hoshino ◽  
Tomoyuki Akutagawa
Keyword(s):  
Hydrogen Bonding ◽  
Liquid Crystal ◽  
Isophthalic Acid ◽  
Molecular Assembly ◽  
Crystal Formation ◽  
Molecular Assemblies

Isophthalic acid derivatives (CnIP), bearing alkylamide chains at the 5-position that can participate in hydrogen bonding, were prepared and evaluated for their hydrogen-bonding molecular assembly structures for organogelation and liquid crystal formation.

scholarly journals The Grapefruit Effect: Interaction between Cytochrome P450 and Coumarin Food Components, Bergamottin, Fraxidin and Osthole. X-ray Crystal Structure and DFT Studies

Molecules ◽  
2020 ◽  
Vol 25 (14) ◽  
pp. 3158
Author(s):  
Miriam Rossi ◽  
Sandjida Aktar ◽  
Marissa Davis ◽  
Emily Hefter Feuss ◽  
Samara Roman-Holba ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Cytochrome P450 ◽  
Intermolecular Interactions ◽  
Active Site ◽  
Molecular Assembly ◽  
Geometrical Parameters ◽  
Crystal Formation ◽  
Strong Inhibitor ◽  
Π Stacking

Coumarins are plant-derived secondary metabolites. The crystal structure of three coumarins—bergamottin, osthole and fraxidin—are described and we analyze intermolecular interactions and their role in crystal formation. Bergamottin is a furanocoumarin found in citrus plants, which is a strong inhibitor of the principal human metabolizing enzyme, cytochrome P450 3A4 (CYP3A4). The crystal structure determinations of three coumarins give us the geometrical parameters and reveal the parallel-displaced π–π stacking and hydrogen bonding intermolecular interactions used for molecular assembly in the crystal structure. A quite strong (less than 3.4 Å) stacking interaction of bergamottin appears to be a determining feature that distinguishes it from other coumarins studied in this work. Our DFT computational studies on the three natural products of the same coumarin family docked into the active site of CYP3A4 (PDB 4D78) show different behavior for these coumarins at the active site. When the substrate is bergamottin, the importance of π-π stacking and hydrogen bonding, which can anchor the substrate in place, appears fundamental. In contrast, fraxidin and osthole show carbonyl coordination to iron. Our docking calculations show that the bergamottin tendency towards π–π stacking is important and likely influences its interactions with the heme group of CYP3A4.

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