- Dictating Nanoparticle Assembly via Systems-Level Control of Molecular Multivalency
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Nanoparticle assembly can be controlled by multivalent binding interactions between surface ligands, indicating that more precise control over these interactions is important to design complex nanoscale architectures. It has been well-established in natural materials that the arrangement of different molecular species in three dimensions can affect the ability of individual supramolecular units to coordinate their binding, thereby regulating the strength and specificity of their collective molecular interactions. However, in artificial systems, limited examples exist that quantitatively demonstrate how changes in nanoscale geometry can be used to rationally modulate the thermodynamics of individual molecular binding interactions. As a result, the use of nanoscale design features to regulate molecular bonding remains an underutilized design handle to control nanomaterials synthesis. Here we demonstrate a polymer-coated nanoparticle material where supramolecular bonding and nanoscale structure are used in conjunction to dictate the thermodynamics of their multivalent interactions, resulting in emergent bundling of supramolecular binding groups that would not be expected on the basis of the molecular structures alone. Additionally, we show that these emergent phenomena can controllably alter the superlattice symmetry by using the mesoscale particle arrangement to alter the thermodynamics of the supramolecular bonding behavior. The ability to rationally program molecular multivalency via a systems-level approach therefore provides a major step forward in the assembly of complex artificial structures, with implications for future designs of both nanoparticle- and supramolecular-based materials.
- Santos, Peter J.,Cao, Zhen,Zhang, Jianyuan,Alexander-Katz, Alfredo,Macfarlane, Robert J.
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- Self-Assembling Nanocomposite Tectons
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The physical characteristics of composite materials are dictated by both the chemical composition and spatial configuration of each constituent phase. A major challenge in nanoparticle-based composites is developing methods to precisely dictate particle positions at the nanometer length scale, as this would allow complete control over nanocomposite structure-property relationships. In this work, we present a new class of building blocks called nanocomposite tectons (NCTs), which consist of inorganic nanoparticles grafted with a dense layer of polymer chains that terminate in molecular recognition units capable of programmed supramolecular bonding. By tuning various design factors, including the particle size and polymer length, we can use the supramolecular interactions between NCTs to controllably alter their assembly behavior, enabling the formation of well-ordered body-centered cubic superlattices consisting of inorganic nanoparticles surrounded by polymer chains. NCTs therefore present a modular platform that enables the construction of composite materials where the composition and three-dimensional arrangement of different constituents within the composite can be independently controlled.
- Zhang, Jianyuan,Santos, Peter J.,Gabrys, Paul A.,Lee, Sangho,Liu, Caroline,Macfarlane, Robert J.
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- Reinforcing Supramolecular Bonding with Magnetic Dipole Interactions to Assemble Dynamic Nanoparticle Superlattices
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Assembling superparamagnetic particles into ordered lattices is an attractive means of generating new magnetically responsive materials, and is commonly achieved by tailoring interparticle interactions as a function of the ligand coating. However, the inherent linkage between the collective magnetic behavior of particle arrays and the assembly processes used to generate them complicates efforts to understand and control material synthesis. Here, we use a synergistic combination of a chemical force (hydrogen bonding) and magnetic dipole coupling to assemble polymer-brush coated superparamagnetic iron oxide nanoparticles, where the relative strengths of these interactions can be tuned to reinforce one another and stabilize the resulting superlattice phases. We find that we can precisely control both the dipole-dipole coupling between nanoparticles and the strength of the ligand-ligand interactions by modifying the interparticle spacing through changes to the polymer spacer between the hydrogen bonding groups and the nanoparticles' surface. This results in modulation of the materials' blocking temperature, as well as the stabilization of a unique superlattice phase that only exists when magnetic coupling between particles is present. Using magnetic interactions to affect nanoparticle assembly in conjunction with ligand-mediated interparticle interactions expands the potential for synthesizing predictable and controllable nanoparticle-based magnetic composites.
- Santos, Peter J.,Macfarlane, Robert J.
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- Chemical synthesis, molecular docking and MepA efflux pump inhibitory effect by 1,8-naphthyridines sulfonamides
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This study aimed to evaluate the antibacterial activity and to verify, in silico and in vitro, the inhibition of efflux mechanisms using a series of synthesized 1,8-naphthyridines sulfonamides against Staphylococcus aureus strains carrying MepA efflux pumps. The chemical synthesis occurred through the thermolysis of the Meldrum's acid adduct. The sulfonamide derivatives were obtained by the sulfonylation of 2-amino-5?chloro-1,8-naphthyridine with commercial benzenesulfonyl chloride. Antibacterial activity was assessed by the broth microdilution test. Efflux pump inhibitory capacity was evaluated in silico by molecular docking and in vitro by analyzing synergistic effects on ciprofloxacin and ethidium bromide (EtBr) and by EtBr fluorescence emission assays. The following 1,8-naphthyridines were synthesized: 4-methyl-N-(5?chloro-1,8-naphthyridin-2-yl)-benzenesulfonamide (Compound 10a); 2,5-dichloro-N-(5?chloro-1,8-naphthyridin-2-yl)-benzenesulfonamide (Compound 10b); 4-fluoro-N-(5?chloro-1,8-naphthyridin-2-yl)-benzenesulfonamide (Compound 10c); 2,3,4-trifluoro-N-(5?chloro-1,8-naphthyridin-2-yl)-benzenesulfonamide (Compound 10d); 3-trifluoromethyl-N-(5?chloro-1,8-naphthyridin-2-yl)-benzenesulfonamide (Compound 10e); 4?bromo-2,5-difluoro-N-(5?chloro-1,8-naphthyridin-2-yl)-benzenesulfonamide (Compound 10f). The 1,8-naphthyridines derivatives associated with sulfonamides did not show antibacterial activity. However, they showed a favorable pharmacokinetic profile with possible MepA efflux pump inhibitory action, demonstrated in molecular docking. In addition to the promising results in reducing the concentration of intracellular EtBr. 1,8-naphthyridines act as putative agents in the inhibitory action of the MepA efflux pump.
- Oliveira-Tintino, Cícera Datiane de Morais,Tintino, Saulo Relison,Muniz, Débora Feitosa,Rodrigues dos Santos Barbosa, Cristina,Pereira, Raimundo Luiz Silva,Begnini, Iêda Maria,Rebelo, Ricardo Andrade,da Silva, Luiz Everson,Mireski, Sandro Lucio,Nasato, Michele Caroline,Krautler, Maria Isabel Lacowicz,Pereira, Pedro Silvino,Balbino, Tereza Cristina Leal,da Costa, José Galberto Martins,Rodrigues, Fabiola Fernandes Galv?o,Teixeira, Alexandre Magno Rodrigues,Barreto, Humberto Medeiros,de Menezes, Irwin Rose Alencar,Coutinho, Henrique Douglas Melo,da Silva, Teresinha Gon?alves
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- METALLO-BETA-LACTAMASE INHIBITORS
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The present invention relates to compounds of formula I that are metallo-β-lactamase inhibitors, the synthesis of such compounds, and the use of such compounds for use with β-lactam antibiotics for overcoming resistance.
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Page/Page column 66
(2017/04/04)
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- Understanding the effects of preorganization, rigidity, and steric interactions in synthetic barbiturate receptors
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Synthetic barbiturate receptors have been utilized for many applications due to their high binding affinities for complementary guests. Although interest in this class of receptors spans from supramolecular to materials chemistry, the effects of receptor steric bulk and preorganization on guest binding affinity has not been studied systematically. To investigate the roles that steric bulk and preorganization play in guest binding, we prepared a series of 12 deconstructed Hamilton receptors with varying degrees of steric bulk and preorganization. Both diethylbarbital and 3-methyl- 7-propylxanthine were investigated as guests for the synthetic receptors. The stoichiometry of guest binding was investigated using Job plots for each host-guest pair, and 1H NMR titrations were performed to measure the guest binding affinities. To complement the solution-state studies, DFT calculations at the B3LYP/6-31+G(d,p) level of theory employing the IEF-PCM CHCl3 solvation model were also performed. Calculated guest binding energies correlated well with the experimental findings and provided additional insight into the factors influencing guest binding. Taken together, the results presented highlight the interplay between preorganization and steric interactions in establishing favorable interactions for self-assembled hydrogenbonded systems.
- McGrath, Jacqueline M.,Pluth, Michael D.
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p. 711 - 719
(2014/04/03)
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- Supramolecular structures of uracil-functionalized PEG with multi-diamidopyridine POSS through complementary hydrogen bonding interactions
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In this study, we synthesized (i) a multi-diamidopyridine-functionalized polyhedral oligomeric silsesquioxane (MD-POSS) through nucleophilic substitution and click 1,3-cycloaddition reactions and (ii) both mono- and bis-uracil (U)-functionalized poly(ethy
- Wang, Jui-Hsu,Altukhov, Oleksii,Cheng, Chih-Chia,Chang, Feng-Chih,Kuo, Shiao-Wei
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p. 5196 - 5206
(2013/07/11)
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- Synthesis of 1,8-naphthyridines and their application in the development of anionic fluorogenic chemosensors
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Two 1,8-naphthyridines were synthesized and found to be fluorescent in solution. These compounds were studied in the presence of Cu+ and Cu2+ ions and it was verified that the metal causes the quenching of their fluorescence emission
- Nicoleti, Celso R.,Garcia, Diogo N.,Da Silva, Luiz E.,Begnini, Iêda M.,Rebelo, Ricardo A.,Joussef, Antonio C.,Machado, Vanderlei G.
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p. 1033 - 1046
(2012/11/07)
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- SUBSTITUTED 2-CARBONYLAMINO-6-PIPERIDINAMINOPYRIDINES AND SUBSTITUTED 1-CARBONYLAMINO-3-PIPERIDINAMINOBENZENES AS 5-HT1F AGONISTS
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ABSTRACT The present invention relates to compounds of formula I: (I) or a pharmaceutically acceptable acid addition salt thereof, where; X is C(R3c= or N=; R1 is C2-C6 alkyl, substituted C2-C6/
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Page/Page column 46
(2010/02/11)
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- Vergleich von in Loesung und mit HPLC bestimmten Bildungsenthalpien ueber Wasserstoffbruecken gebundener Wirt-Gast-Komplexe
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Keywords: Heterocyclen, HPLC, Supramolekulare Chemie, Wasserstoffbruecken
- Zimmerman, Steven C.,Kwan, Wing-Sum
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p. 2589 - 2592
(2007/10/03)
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