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Jonathan L. Sessler - One of the best experts on this subject based on the ideXlab platform.
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Pyrrole N-H Anion Complexes.
Coordination chemistry reviews, 2017Co-Authors: Gabriela I. Vargas-zúñiga, Jonathan L. SesslerAbstract:Synthetic pyrrole-based anion receptors date back to the 1990s. They have been extensively developed in the context of macrocyclic systems as expanded porphyrins and Calixpyrroles, and related systems. The chemistry of open-chain pyrrolic systems is, in many respects, no less venerable. It also has more direct analogy to naturally occurring pyrrole-based anion binding motifs. However, it has not been the subject of a comprehensive review. Presented herein is a summary of efforts devoted to the creation of de novo pyrrole-based receptors, as well as the anion recognition chemistry of naturally occurring pyrrolic systems as prodigiosins and their synthetic analogues.
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Functionalized Calixpyrroles: Building Blocks for Self-Assembly
Calixarenes and Beyond, 2016Co-Authors: Gabriela I. Vargas-zúñiga, Jonathan L. Sessler, Steffen BähringAbstract:This chapter covers advances in the development of anion and ion pair recognition systems based on calix[4]pyrrole. The intention of this manuscript is to provide of an overview of promising systems for the sensing of relevant analytes, such as the toxic fluoride anion, phosphate anions, as well as the extraction and transport of anionic species and ion pairs including cesium halide and sulfate salts. It is divided into seven sections. The first section describes the synthetic methods employed to functionalized calix[4]pyrrole. The second section focuses on functionalized calix[4]pyrroles that display enhanced anion binding properties compared to the non-functionalized parent system, octamethylcalix[4]pyrrole. The use of functionalized calix[4]pyrroles containing a fluorescent group or functionalized calix[4]pyrroles as building blocks for the preparation of stimulus-responsive materials is discussed in Sect. 12.3. Receptors that are able to recognize and selectively extract ionic species from aqueous media into organic environments are the topic of Sect. 12.4. Anion and ion pair receptors based on calix[4]pyrroles that are designed to achieve the transmembrane transport of ions are the focus of the fifth section. Finally, the last section will summarize work devoted on calix[4]pyrrole systems capable of forming higher order supramolecular aggregates and capsules, as well as studies of their response to external stimuli. Potential applications, including the possible removal of deleterious anions and the eventual development of therapeutics that function via the transport of anions across cell membranes, are discussed.
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An imidazolium-functionalized self-assembling calix[4]pyrrole
Chemical Communications, 2014Co-Authors: Abdullah Aydogan, Jonathan L. SesslerAbstract:A calixpyrrole bearing a tethered imidazolium functional group was prepared in the form of its bromide salt. This compound was found to undergo self-assembly to produce supramolecular polymers, wherein both the bromide anion and the imidazolium cation are bound to the calixpyrrole core.
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A Calix[2]phenol[2]pyrrole and a Fused Pyrrolidine-Containing Derivative.
ChemInform, 2012Co-Authors: Kwang-bok Jung, Dong-gyu Cho, Vincent M. Lynch, Sung Kuk Kim, Jonathan L. SesslerAbstract:Two new hybrid calixarene-calixpyrrole systems (III) and (V) are prepared according to the scheme.
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Palladium induced macrocyclic preorganization for stabilization of a tetrathiafulvalene mixed-valence dimer.
Organic letters, 2011Co-Authors: Christopher Bejger, Vincent M. Lynch, Jason B. Love, Christina M. Davis, Jung Su Park, Jonathan L. SesslerAbstract:Ditopic metalation of a flexible "Pacman"-like tetrathiafulvalene (TTF) modified Schiff-base-calixpyrrole results in the stabilization upon oxidation of an otherwise difficult-to-access mixed-valence TTF radical dimer. EPR and optical spectroscopies were used to characterize the mixed-valence species.
Vincent M. Lynch - One of the best experts on this subject based on the ideXlab platform.
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A Calix[2]phenol[2]pyrrole and a Fused Pyrrolidine-Containing Derivative.
ChemInform, 2012Co-Authors: Kwang-bok Jung, Dong-gyu Cho, Vincent M. Lynch, Sung Kuk Kim, Jonathan L. SesslerAbstract:Two new hybrid calixarene-calixpyrrole systems (III) and (V) are prepared according to the scheme.
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Palladium induced macrocyclic preorganization for stabilization of a tetrathiafulvalene mixed-valence dimer.
Organic letters, 2011Co-Authors: Christopher Bejger, Vincent M. Lynch, Jason B. Love, Christina M. Davis, Jung Su Park, Jonathan L. SesslerAbstract:Ditopic metalation of a flexible "Pacman"-like tetrathiafulvalene (TTF) modified Schiff-base-calixpyrrole results in the stabilization upon oxidation of an otherwise difficult-to-access mixed-valence TTF radical dimer. EPR and optical spectroscopies were used to characterize the mixed-valence species.
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Novel β-substituted calix[4]pyrroles
Journal of Porphyrins and Phthalocyanines, 2009Co-Authors: Jonathan L. Sessler, Vladimir V. Roznyatovskiy, Vincent M. LynchAbstract:Calix[4]pyrroles have attracted considerable attention within the macrocyclic, supramolecular, and porphyrin analog communities due to their ability to act as simple-to-synthesize receptors for common anions, such as chloride and fluoride. Reported here is what we believe is a new, potentially generalizable route to fully β-alkyl substituted Calixpyrroles. These products are accessible from the starting pyrrolic esters, and are obtained via simple reaction with CH 3 Li , followed by subsequent quenching with HCl in ether. A representative system has been characterized by X-ray diffraction analysis. The present route allows access to calix[4]pyrroles bearing functionality, such as double bonds, off the so-called C-rim; such systems are of interest because they could allow for further synthetic elaborations and permit incorporation of calix[4]pyrroles into more complex structures.
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Poly(methyl methacrylate)s with pendant Calixpyrroles: polymeric extractants for halide anion salts
Chemical communications (Cambridge England), 2008Co-Authors: Abdullah Aydogan, Vincent M. Lynch, Ahmet Akar, Manuel Marquez, Daniel J. Coady, Christopher W. Bielawski, Jonathan L. SesslerAbstract:Poly(methyl methacrylate)s containing pendant octamethylcalix[4]pyrrole subunits were prepared and demonstrated to be capable of extracting tetrabutylammonium chloride and fluoride salts from aqueous media.
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Calix[4]pyrroles with Long Alkyl Chains: Synthesis, Characterization, and Anion Binding Studies
Supramolecular Chemistry, 2008Co-Authors: Abdullah Aydogan, Jonathan L. Sessler, Ahmet Akar, Vincent M. LynchAbstract:Calix[4]pyrrole derivatives bearing long n-alkyl ester chains have been synthesized from calix[4]pyrroles containing carboxylic acid functional groups. These systems, which contain ester groups on either the meso- carbon atoms of the calixpyrrole ring or the β-positions of individual pyrrole rings, were prepared from the corresponding carboxylic acids. Esterification was effected using dicyclohexylcarbodiimide/4-dimethylaminopyridine (DCC/DMAP) to obtain long alkyl chain substituted calix[4]pyrroles. In the context of this work, several brominated calixpyrrole derivatives were prepared using N-bromosuccinimide (NBS) as the brominating agent. Anion binding studies carried out by isothermal titration calorimetry (ITC) in 1,2-dichloroethane with Cl− and in the form of their respective tetrabutylammonium salts, revealed that the functionalized ester derivatives have anion binding affinities similar to those of the unsubstituted “parent” systems, octamethylcalix[4]pyrrole (1) and β-octabromocalix[4]pyrrole (2...
Philip A. Gale - One of the best experts on this subject based on the ideXlab platform.
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Tetrapodal Anion Transporters.
Molecules (Basel Switzerland), 2020Co-Authors: Alexander M. Gilchrist, Lijun Chen, William Lewis, Ethan N. W. Howe, Lauren K. Macreadie, Philip A. GaleAbstract:Synthetic anion transporters that facilitate chloride transport are promising candidates for channelopathy treatments. However, most anion transporters exhibit an undesired side effect of facilitating proton transport via interacting with fatty acids present in the membrane. To address the limitation, we here report the use of a new tetrapodal scaffold to maximize the selective interaction with spherical chloride over binding the carboxylate headgroup of fatty acids. One of the new transporters demonstrated a high selectivity for chloride uniport over fatty acid-induced proton transport while being >10 times more active in chloride uniport than strapped Calixpyrroles that were previously the only class of compounds known to possess similar selectivity properties.
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Selective anion transport mediated by strap-extended Calixpyrroles
Journal of Porphyrins and Phthalocyanines, 2020Co-Authors: Harriet J. Clarke, Mark E. Light, Philip A. GaleAbstract:Synthetic anion receptors that facilitate transmembrane chloride transport are of interest as potential therapeutic agents for cancer and cystic fibrosis. Transporters selective for chloride over p...
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Calix[n]pyrroles as anion and ion-pair complexants
Topics in Heterocyclic Chemistry, 2010Co-Authors: Philip A. Gale, Chang-hee LeeAbstract:Abstract This chapter covers advances in calixpyrrole chemistry and specifically in the application of these species as anion and ion-pair complexation agents over the last 5 years. Over this time, the chemistry of these easy-to-make macrocycles advanced with the discovery of the ion-pair complexation properties of Calixpyrroles, in addition to the development of strapped Calixpyrroles that incorporate extra hydrogen bond donors and possess higher affinities for anions than the parent macrocycle. Calixpyrroles have also been employed as anion complexants in solvent–solvent extraction and in polymers. They have also been shown to function as lipid bilayer transport agents for salts and as organocatalysts.
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Bis-cation salt complexation by meso-octamethylcalix[4]pyrrole: linking complexes in solution and in the solid state.
Organic & biomolecular chemistry, 2009Co-Authors: Claudia Caltagirone, Jonathan L. Sessler, Mark E. Light, Dustin E. Gross, Nathan L. Bill, Philip A. GaleAbstract:Pyridinium and imidazolium bis-cations are shown to link calix[4]pyrrole anion complexes both in solution and in the solid state. This is accomplished by binding of the bis-cations to the electron-rich bowl shaped cavities formed by two separate calixpyrrole–anion complexes. These resulting sandwich-type structures provide a new way of organising calix[4]pyrrole anion complexes in space.
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Calix[4]pyrrole as a chloride anion receptor: solvent and countercation effects.
Journal of the American Chemical Society, 2006Co-Authors: Jonathan L. Sessler, Won Seob Cho, Vincent M. Lynch, Gareth W. Bates, Mark E. Light, Dustin E. Gross, Franz P. Schmidtchen, Philip A. GaleAbstract:The interaction of calixpyrrole with several chloride salts has been studied in the solid state by X-ray crystallography as well as in solution by isothermal titration calorimetry (ITC) and 1H NMR spectroscopic titrations. The titration results in dimethylsulfoxide, acetonitrile, nitromethane, 1,2-dichloroethane, and dichloromethane, carried out using various chloride salts, specifically tetraethylammonium (TEA), tetrapropylammonium (TPA), tetrabutylammonium (TBA), tetraethylphosphonium (TEP), tetrabutylphosphonium (TBP), and tetraphenylphosphonium (TPhP), showed no dependence on method of measurement. The resulting affinity constants (Ka), on the other hand, were found to be highly dependent on the choice of solvent with Ka's ranging from 102−105 M-1 being recorded in the test solvents used for this study. In dichloromethane, a strong dependence on the countercation was also seen, with the Ka's for the interaction with chloride ranging from 102−104 M-1. In the case of TPA, TBA, and TBP, the ITC data coul...
Jason B. Love - One of the best experts on this subject based on the ideXlab platform.
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Pressure-induced inclusion of neon in the crystal structure of a molecular Cu2(pacman) complex at 4.67 GPa.
Chemical communications (Cambridge England), 2020Co-Authors: Nico Giordano, Christine M. Beavers, Konstantin V. Kamenev, Jason B. Love, James R. Pankhurst, Simon J. Teat, Simon ParsonsAbstract:Crystals of a Cu complex of the macrocyclic Schiff-base calixpyrrole or 'Pacman' ligand, Cu2(L), do not contain any solvent-accessible void space at ambient pressure, but adsorb neon at 4.67 GPa, forming Cu2(L)·3.5Ne.
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Macrocyclic Platforms for the Construction of Tetranuclear Oxo and Hydroxo Zinc Clusters
Organometallics, 2015Co-Authors: Thomas Cadenbach, James R. Pankhurst, Tommy A. Hofmann, Massimiliano Curcio, Polly L. Arnold, Jason B. LoveAbstract:The design of ligands that can act as platforms for the controlled, “bottom-up” synthesis of transition-metal clusters is a promising approach to accessing enzymatic mimics and new small-molecule reaction chemistry. This approach is exemplified here through the coordination chemistry of two compartmental Schiff-base Calixpyrroles (H4L) that usually act as dinucleating ligands for transition metals. While reactions between H4L and Zn{N(SiMe3)2}2 form the expected dinuclear Zn “Pacman” complexes Zn2(L), reactions with ZnEt2 result in the tetranuclear Zn alkyl complexes Zn4Et4(THF)4(L), in which open, “bowl-shaped” structures are adopted due to the flexibility of the macrocyclic platform. The outcome of hydrolysis reactions of these tetranuclear complexes is found to depend on the macrocyclic cavity size, with the smaller macrocycle favoring oxo formation in Zn4(μ4-O)Et2(L) and the larger macrocycle favoring complete hydrolysis to form the hydroxide-bridged cluster Zn4(μ2-OH)4(L). This latter complex reacts ...
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Macrocyclic Platforms for the Construction of Tetranuclear Oxo and Hydroxo Zinc Clusters
2015Co-Authors: Thomas Cadenbach, Tommy A. Hofmann, Massimiliano Curcio, Polly L. Arnold, James R. Pankhurst, Jason B. LoveAbstract:The design of ligands that can act as platforms for the controlled, “bottom-up” synthesis of transition-metal clusters is a promising approach to accessing enzymatic mimics and new small-molecule reaction chemistry. This approach is exemplified here through the coordination chemistry of two compartmental Schiff-base Calixpyrroles (H4L) that usually act as dinucleating ligands for transition metals. While reactions between H4L and Zn{N(SiMe3)2}2 form the expected dinuclear Zn “Pacman” complexes Zn2(L), reactions with ZnEt2 result in the tetranuclear Zn alkyl complexes Zn4Et4(THF)4(L), in which open, “bowl-shaped” structures are adopted due to the flexibility of the macrocyclic platform. The outcome of hydrolysis reactions of these tetranuclear complexes is found to depend on the macrocyclic cavity size, with the smaller macrocycle favoring oxo formation in Zn4(μ4-O)Et2(L) and the larger macrocycle favoring complete hydrolysis to form the hydroxide-bridged cluster Zn4(μ2-OH)4(L). This latter complex reacts with carbon dioxide at elevated temperature, re-forming the free macrocycle H4L and eliminating ZnCO3
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Palladium induced macrocyclic preorganization for stabilization of a tetrathiafulvalene mixed-valence dimer.
Organic letters, 2011Co-Authors: Christopher Bejger, Vincent M. Lynch, Jason B. Love, Christina M. Davis, Jung Su Park, Jonathan L. SesslerAbstract:Ditopic metalation of a flexible "Pacman"-like tetrathiafulvalene (TTF) modified Schiff-base-calixpyrrole results in the stabilization upon oxidation of an otherwise difficult-to-access mixed-valence TTF radical dimer. EPR and optical spectroscopies were used to characterize the mixed-valence species.
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Tailoring dicobalt Pacman complexes of Schiff-base Calixpyrroles towards dioxygen reduction catalysis.
Chemical communications (Cambridge England), 2009Co-Authors: Elham Askarizadeh, Sahar Bani Yaghoob, Davar M. Boghaei, Alexandra M. Z. Slawin, Jason B. LoveAbstract:By modifying the mouth of a macrocyclic dicobalt Pacman complex, it is possible to both isolate new bridging-superoxo and hydroxyl complexes and to tune the reactivity of this system towards catalytic four-electron reduction of dioxygen to water.
Hiroshi Imahori - One of the best experts on this subject based on the ideXlab platform.
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Phosphole-containing Calixpyrroles, calixphyrins, and porphyrins: synthesis and coordination chemistry.
Accounts of Chemical Research, 2009Co-Authors: Yoshihiro Matano, Hiroshi ImahoriAbstract:Porphyrins are large heterocyclic macrocycles that bind metals to form complexes such as heme and chlorophyll. Porphyrinogens are related macrocycles in which the meso-carbons, the carbon atoms connecting the pyrroles or the related five-atom heterocycles, are all or partially reduced to methylene, disrupting the π-electron conjugation. Both porphyrins and porphyrinogens are important components of natural and synthetic systems, and they have completely different coordination behavior. Consequently, the coordination chemistry of the entire porphyrin family, including regular porphyrins, porphyrinogens, and their expanded analogs, has been extensively investigated. Core modification, namely, replacing one or more pyrrole rings with other heterocyclic or carbocyclic rings, is a highly promising approach for creating unprecedented coordination properties in the porphyrin family. The size, shape, charge, and binding ability of the core-modified porphyrin platforms are readily tunable by variation of the heter...
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Phosphole-containing Calixpyrroles, calixphyrins, and porphyrins: synthesis and coordination chemistry.
Accounts of chemical research, 2009Co-Authors: Yoshihiro Matano, Hiroshi ImahoriAbstract:Porphyrins are large heterocyclic macrocycles that bind metals to form complexes such as heme and chlorophyll. Porphyrinogens are related macrocycles in which the meso-carbons, the carbon atoms connecting the pyrroles or the related five-atom heterocycles, are all or partially reduced to methylene, disrupting the pi-electron conjugation. Both porphyrins and porphyrinogens are important components of natural and synthetic systems, and they have completely different coordination behavior. Consequently, the coordination chemistry of the entire porphyrin family, including regular porphyrins, porphyrinogens, and their expanded analogs, has been extensively investigated. Core modification, namely, replacing one or more pyrrole rings with other heterocyclic or carbocyclic rings, is a highly promising approach for creating unprecedented coordination properties in the porphyrin family. The size, shape, charge, and binding ability of the core-modified porphyrin platforms are readily tunable by variation of the heterole subunits. Until recently, however, the only atoms that could be incorporated into the core were carbon and chalcogens (the oxygen family). Phosphole, the phosphorus isologue of pyrrole, is considered a nonaromatic heterole because of insufficient pi-conjugation between the cis-dienic pi-system and the lone electron pair of the phosphorus atom. As a consequence, phospholes behave not only as efficient pi-conjugative frameworks but also as ordinary phosphine ligands for transition metals. With this in mind, we started a research project on core-modified porphyrins in which the phosphole subunit plays a crucial role in providing characteristic coordination environments. In this Account, we describe our efforts to explore the utility of phosphole-containing porphyrins and porphyrinogens as macrocyclic, mixed-donor ligands. We have established convenient methods for the synthesis of Calixpyrroles, calixphyrins, and porphyrins with P and either O or S substitutions, that is, P,X,N(2)-hybrids, as well as the phosphatripyrrane precursors. We also have investigated the effects of varying the combination of core heteroatoms (P, N, S, and O) on the coordination properties of the hybrid macrocycles. Our recent investigations have shown that (1) the P,S,N(2)-Calixpyrroles behave as monophosphine ligands while maintaining the hosting functions that originate from the pyrrole subunits, (2) the P,X,N(2)-calixphyrins behave as neutral, monoanionic, or dianionic tetradentate ligands with electronic structures that vary widely depending on the combination of heterole subunits, and (3) the P,S,N(2)-porphyrin behaves as a redox-active pi-ligand for group 10 (the Ni family) metals, affording a novel class of core-modified isophlorin complexes. As a whole, the incorporation of the phosphole subunit into the macrocyclic framework provides unprecedented coordinating properties for the porphyrin family, affording exceptional synthetic control over the behavior of these important macrocycles.
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Synthesis, Structures, and Coordinating Properties of Phosphole-Containing Hybrid Calixpyrroles
Organometallics, 2008Co-Authors: Takashi Nakabuchi, Yoshihiro Matano, Hiroshi ImahoriAbstract:Symmetric and asymmetric hybrid Calixpyrroles containing a σ4-phosphole or σ4-2,3-dihydrophosphole unit (symmetric and asymmetric σ4-P,N2,X-hybrids: X = S, O) were prepared by using acid-promoted condensation reactions of the corresponding σ4-phosphatripyrranes with 2,5-bis(1-hydroxy-1-methylethyl)heteroles. The X-ray crystallographic analyses of the symmetric and asymmetric σ4-P,N2,X-hybrids show that the cavity sizes of the σ4-P,N2,S-hybrids are larger than those of the σ4-P,N2,O-hybrids, mainly reflecting the difference in edge-to-edge distances of the thiophene and furan rings. The symmetric σ4-P,N2,X-hybrids and the asymmetric σ4-P,N2,S-hybrid were successfully converted to the corresponding σ3 forms by reductive desulfurization at the phosphorus center. Each of the symmetric σ3-P,N2,X-hybrids was obtained as a mixture of two conformers, where the lone pair of the phosphorus atom is located inside (in) and outside (out) the cavity. The interconversion between the in and out type conformers of the asy...
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Phosphole-Containing Hybrid Calixpyrroles: New Multifunctional Macrocyclic Ligands for Platinum(II) Ions
Organometallics, 2006Co-Authors: Yoshihiro Matano, Takashi Nakabuchi, Tooru Miyajima, Hiroshi ImahoriAbstract:Phosphole-containing hybrid Calixpyrroles have been prepared by acid-promoted condensation reactions. σ3-Calix[1]phosphole[1]thiophene[2]pyrrole reacts with PtCl2(COD) to afford an unusual type of macrocyclic Pt(II)−monophosphine complex bearing a η3-cyclooctadienyl ligand, in which the phosphole and pyrrole units bind the Pt−Cl moiety through cooperative, noncovalent bonding interactions.
