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2-Amino-7,4′-dimethoxyisoflavone (I), C_(17)H _(15)NO_4 and 2-amino-7-methoxy-4′-hydroxyisoflavone (II), C_(16)H_(13)NO_4 were synthesized and their crystal structures were determined by single-crystal X-ray diffraction. They al...
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2-Amino-7,4′-dimethoxyisoflavone (I), C_(17)H _(15)NO_4 and 2-amino-7-methoxy-4′-hydroxyisoflavone (II), C_(16)H_(13)NO_4 were synthesized and their crystal structures were determined by single-crystal X-ray diffraction. They all crystallize in the monoclinic crystal system, space group P21/c. The cell dimensions of I are a = 15.6673(17) ?, b = 7.3998(8) ?, c = 13.2919(14) ?, β = 111.4460(10)°, D _c = 1.377 mg/mm~3, V = 1,434.3(3) A~3, Z = 4 and those of II are a = 10.990(7) ?, b = 11.879(7) ?, c = 10.422(6) ?, β = 96.904(11)°, D _c = 1.393 mg/mm~3, V = 1,350.8(14) A~3, Z = 4. A combination of F-type and T-type aromatic-aromatic interaction and hydrogen bonding links the molecules of I into a tri-dimensional framework structure. In the crystal structure of II, paired tri-centered hydrogen bond generates a R _4~2 (21) ring and the R _4~2 (21) rings link the molecules into a sheet. Graphical Abstract: A combination of F-type and T-type aromatic-aromatic interaction and hydrogen bonding links the molecules of 2-amino-4′,7-dimethoxyisoflavone into a tri-dimensional framework structure. In the crystal structure of 2-amino-7-methoxy-4′-hydroxyisoflavone, paired tri-centered hydrogen bond generates a R _4~2 (21) ring and the R _4~2 (21) rings link the molecules into a sheet. [Figure not available: see fulltext.]
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The stacking contacts between two resonance-assisted hydrogen-bridged (RAHB) rings and stacking contacts between RAHB rings and C-6-aromatic groups are frequently found at large horizontal displacements in the crystal structures f...
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The stacking contacts between two resonance-assisted hydrogen-bridged (RAHB) rings and stacking contacts between RAHB rings and C-6-aromatic groups are frequently found at large horizontal displacements in the crystal structures found in the Cambridge Structural Database (CSD), particularly in the range of 4.0-6.0 and 5.5-6.5 A, respectively. Ab initio calculations reveal that interactions at large offsets, although weaker than interactions at smaller offsets, can be significant, since a large portion of interaction energy (in some systems up to 66%) can be preserved upon shifting to larger offset values.
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The interaction between 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin and different polycations is studied by UV—vis spectroscopy. Two polycations containing charged aromatic residues (imidazolium and pyridinium) have been ea...
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The interaction between 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin and different polycations is studied by UV—vis spectroscopy. Two polycations containing charged aromatic residues (imidazolium and pyridinium) have been easily synthesized by Paal-Knorr reaction of alternating aliphatic polyketones with histamine and 4-picolylamine. It was found that these polymers stabilize the tetra-anionic form of the porphyrin at acidic conditions, and avoid the formation of H- and J-type self-aggregates. Other polycations such as poly(allylamine) and poly(decylviologen) enhance porphyrin self-aggregation. As the latter polymer has also aromatic charged groups, the influence of the polymer structure as a whole in the behavior of the porphyrin/polycation system is highlighted. In this context, similar but not equal results have been found comparing the influence of the polyketone derivative containing pyridinium groups and the polycation poly(4-vinylpyridine) on the porphyrin self-aggregation and acid—base behavior.
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Two novel sulfonyl-embedded reversed phase materials with sulfonic acid moieties (SOx-RP) were prepared by a simple oxidation of two silica-based sulfur-embedded RP-phases (S-RP). The chromatographic behavior of the resultant sulf...
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Two novel sulfonyl-embedded reversed phase materials with sulfonic acid moieties (SOx-RP) were prepared by a simple oxidation of two silica-based sulfur-embedded RP-phases (S-RP). The chromatographic behavior of the resultant sulfonyl/sulfonic acid-embedded phase C3-SO2-C18/SO3H and the sulfonyl-embedded phase C-3-SO2-C14 e.c. (silanol endcapped) was extensively elucidated with a number of well-established as well as self-assembled column tests. These SOx-RP phases were also compared with their corresponding S-RP phases as well as with two commercial carbonyl-containing RP phases (CO-RP) with amide- and urea-embedding. The SOx-RP phases were found to exhibit exceptionally high planar recognition ability for polyaromatic analytes at comparable retention times to the investigated CO-R-P phases and highly reduced retention compared to the parent, non-oxidized S-RP-materials. The results of this study suggest that the selectivity enhancement observed with the S-oxidized phases is due to sulfonyl-pi and sulfonic acid-pi interactions. Furthermore these novel SOx-RP phases proved to be fully applicable under 100% aqueous mobile-phase conditions making them a useful alternative to conventional RP as well as polar-embedded CO-RP phases.
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? 2023 Elsevier B.V.Nanomedicines containing the aromatic drug chloroquine and the polymer poly(sodium 4-styrenesulfonate) have been theoretically designed and experimentally synthesized following the simple mixture of two aqueous...
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? 2023 Elsevier B.V.Nanomedicines containing the aromatic drug chloroquine and the polymer poly(sodium 4-styrenesulfonate) have been theoretically designed and experimentally synthesized following the simple mixture of two aqueous solutions containing the drug and the polymer, respectively. Theoretical calculations show higher binding energy between both the aromatic polymer and chloroquine, and a higher tendency to release water from their hydration spheres, as compared to the binding between the drug and the aliphatic polymer poly(sodium vinyl sulfonate). MD simulations show the spontaneous formation of stable structures of 10 nm of average diameter, even combining short polymer chains, highly diluted reactants, and short reaction time (in the range of μs). Rapid mixture of the liquids in a stopped flow equipment shows nanoparticle formation in the range of tenths of seconds. Equilibration studies in the range of minutes evidence spheroidal nanoparticles with almost quantitative association efficiency, 48.6 % of drug loading, size of 170 – 410 nm, low polydispersity (PdI = 0.25 – 0.47), and negative zeta potential (-18 – ?45 mV). They provide drug release for 30 days, and are stable to NaCl exposure, pH gradient, several temperature values, and long-term storage. Furthermore, we demonstrate scaling up of the nanomedicine production upon increasing the reaction volume. Our studies demonstrate that these highly loaded drug nanoparticles are based on the occurrence of site-specific short-range interactions between the drug and the aromatic excipient such as π-stacking. In the absence of the aromatic group in the polymer, weak interactions and unstable formulations are evidenced, both theoretically and experimentally. The combination of the selected theoretical and experimental tools could promote the efficient production of drug / polyelectrolyte formulations with therapeutical applications. The chosen components could be considered as potential medicines or as model components to design, develop, characterize, and scale up medicines comprising other combinations of drugs and polymers.
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The MM2 method has been modified using a three-center charge model aimed at determining stacking geometries. The stacking interactions for the benzene dimer, porphine dimer, and bis( 4,5-diazafluoren-9-one thiosemicarbazonato)pall...
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The MM2 method has been modified using a three-center charge model aimed at determining stacking geometries. The stacking interactions for the benzene dimer, porphine dimer, and bis( 4,5-diazafluoren-9-one thiosemicarbazonato)palladium(II) have been assessed with both the three-center charge model and the conventional single-center charge model using the MM2 method. The modified MM2 method always gave better results than the conventional method, and the obtained structures by the former method are in good~greement with the proposed structures from those theoretical and experimental results. The possible advantages of using the three-center charge model for complex systems are also discussed.
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The elucidation of the mechanism of the substituent influence on the properties P (the interaction energies E, interring distances l, and free energies Delta G of interaction) of weak complexes involving aromatic rings is of impor...
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The elucidation of the mechanism of the substituent influence on the properties P (the interaction energies E, interring distances l, and free energies Delta G of interaction) of weak complexes involving aromatic rings is of importance not only theoretically but also from a practical standpoint. This mechanism is little understood. In this work, the literature data on the substituent influence on P properties for 42 series of complexes have been analyzed, using correlation analysis. Generally, the inductive, resonance, polarizability, and steric effects are in operation. The presence or absence of certain effects and the relation between their contributions are determined by the type of series. The polarizability effect (an electrostatic ion-dipole interaction) is caused by an excess charge appearing on the ring substituted fragment of complexes as a result of the complexation. This effect is observed in all series; its contribution ranges up to approximately 50%.
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A new green and simple method of synthesis of polymeric nanoparticles comprising a pH-responsive polymer and a sulfonated dye, without needing the use of any organic solvent or cross-linker, is shown. It is based on the complexati...
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A new green and simple method of synthesis of polymeric nanoparticles comprising a pH-responsive polymer and a sulfonated dye, without needing the use of any organic solvent or cross-linker, is shown. It is based on the complexation between weak basic aromatic polyelectrolytes and a strong acidic dye by means of aromatic-aromatic interactions in water at acidic pH, and subsequent fast pH change, which triggers a controlled collapse of the system in the form of nanoparticles. Poly(4-vinylpyridine) and the tetrasulfonated azo dye 4,4'-((1E,1'E)-(3,3'-dimethyl-[1,1' biphenyl]-4,4'diyl)bis(diazen-2,1-diy1))bis(3-hidroxynaphtalen-2,7-disulfonate) form complexes at pH 3-5, undergoing short-range aromatic-aromatic interactions, as seen by H-1 NMR. Subsequent and fast pH adjustment to 9-10 leads to the system collapse with faster kinetics than those for the hydration and release of the hydrophilic negatively charged dye, so that polymeric nanoparticles are formed that include the dye, which acts as stabilizer. The monomodal distributed nanoparticles showed 50-200 nm of hydrodynamic diameter, with PDI ranging between 0.1 and 0.4, and zeta potential values in the range - 40 to - 60 mV, resulting stable for at least 14 days. The synthesized nanoparticles have been included in calcium alginate beads, showing colorimetric sensitivity to pH changes in water. We envisage that our findings could be also applied in other hydrophilic-aromatic polymers to create stable and functional materials by using this simple and green methodology.
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Oligo-chitosans were chemically modified with dinitrophenyl groups for selective and rapid adsorption of amitriptyline by forming pi-pi complexes.~1H-NMR was utilized not only for characterization of modified chitosans but also fo...
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Oligo-chitosans were chemically modified with dinitrophenyl groups for selective and rapid adsorption of amitriptyline by forming pi-pi complexes.~1H-NMR was utilized not only for characterization of modified chitosans but also for monitoring the aromatic-aromatic interaction.The variation in the chemical shift of aromatic protons was followed to monitor the aromatic-aromatic interaction.Upfield shift of aromatic protons of dinitrophenyl groups supports aromatic-aromatic interactions with amitriptyline.Drug uptake test by HPLC reveals that dinitrophenyl chitosan particles (1-2mum) at 0.4 wt% (w/v) in a saline solution (pH 6.9) adsorb 90% amitriptyline within 30 min.
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Aerogels made of chitosan and chondroitin sulfate, and containing 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin have been synthesized. The aerogels presented a microstructure made of microfibers and microsheets, with porosity ...
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Aerogels made of chitosan and chondroitin sulfate, and containing 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin have been synthesized. The aerogels presented a microstructure made of microfibers and microsheets, with porosity higher than 99%. The dispersion and state of aggregation of the dye in the solids have been controlled with the aid of aromatic polyelectrolytes able to produce aromatic-aromatic interactions. Thus, non-homogenous dispersions of the dye as J-aggregates and formation of microcrystals on the microsheet surface were observed in the absence of the aromatic polymers; on the contrary, well dispersed H-aggregates of the dye were observed in the presence of poly(decylviologen), and well dispersed complexed monomeric dye molecules were found in the presence of a polyketone derivatized with hystamine, thus presenting imidazolium pendant groups. The same state of aggregation has been observed in solution for the respective complexes, highlighting the potential of aromatic-aromatic interactions to achieve a control of the state of aggregation of dyes in solution and further transfer to the solid state keeping their photophysical properties, and furnishing means for a good dispersion of the dyes in solid materials. (C) 2016 Elsevier Ltd. All rights reserved.
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