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Sessler, Jonathan L. Pyrrole-based anion receptors : binding studies and progress towards attachment to solid support
No full texttextAnions have a wide range of importance both in chemical, as well as biological, systems; thus, the design and synthesis of novel receptors with the ability to selectively recognize or bind a specific class of anions is a rapidly developing field of supramolecular chemistry. A series of novel, acyclic pyrrole-based anion receptors will be presented. These systems, which are based on pyridine 2,6-dicarboxamides, bind nitrite and carboxylate anions with good selectivity in dichloroethane solution and are also capable of binding cyanide anions weakly. Control systems, incorporating a benzene-1,3-dicarboxamide spacer, or those wherein the connectivity of the amide linkage is "reversed," either failed to act as effective anion receptors or displayed very different selectivities. Such observations provide support for the notion that small perturbations in the structure of these receptors can lead to drastic changes in their anionbinding properties. Furthermore, efforts have been made to attach macrocyclic phosphate-binding receptors developed in the Sessler Group to cellulose solid supports. The idea is that these macrocycles, once bound to cellulose, will be capable of extracting phosphate from solutions. Studies on the macrocyclic loading level and extraction abilities of the receptors are underway, and will be presented herein.Chemistr
Anion binding and electrochemical properties of calix[4]pyrrole ferrocene conjugates
No full textTwo new ferrocene calixpyrrole conjugate compounds have been synthesized and their electrochemical properties studied in the absence and presence of anions
A Dicationic Calix 4 Pyrrole Derivative and Its Use for the Selective Recognition and Displacement-Based Sensing of Pyrophosphate
Full text linkA new bis-pyridinium calix[4] pyrrole derivative is reported. This system forms a non-fluorescent complex upon exposure to the chromenolate anion. The resulting supramolecular ensemble binds the pyrophosphate anion with high affinity (K-a (2.55 +/- 0.12) x 10(7) M-1) in acetonitrile. It exhibits sensitive "turn-on" fluorescence when exposed to tetrabutylammonium pyrophosphate, and does so in preference to other anions, including the fluoride and phosphate anions.NRF 2009-0087013BK21 programNational Science Foundation NSF CHE-1057904Chemistr
Naphthalimide Trifluoroacetyl Acetonate: A Hydrazine-Selective Chemodosimetric Sensor
Full text linkThe trifluoroacetyl acetonate naphthalimide derivative 1 has been synthesized in good yield. In acetonitrile solution, compound 1 reacts selectively with hydrazine (NH2NH2) to give a five-membered ring. This leads to OFF-ON fluorescence with a maximum intensity at 501 nm as well as easily discernible color changes. Based on a readily discernible and reproducible 3.9% change in overall fluorescence intensity, the limit of detection for 1 is 3.2 ppb (0.1 mu M), which is below the accepted limit for hydrazine set by the U.S. Environmental Protection Agency (EPA). Compound 1 is selective for hydrazine over other amines, including NH4OH, NH2OH, ethylenediamine, methylamine, n-butylamine, piperazine, dimethylamine, triethylamine, pyridine, and is not perturbed by environmentally abundant metal ions. When supported on glass-backed silica gel TLC plates, compound 1 acts as a fluorimetric and colorimetric probe for hydrazine vapor at a partial pressure of 9.0 mm Hg, with selectivity over other potentially interfering volatile analytes, including ammonia, methylamine, n-butylamine, formaldehyde, acetaldehyde, H2O2, HCl, and CO2 being observed. Probe 1 can also be used for the detection of hydrazine in HeLa cells and does so without appreciable interference from other biologically abundant amines and metal ions.U.S. National Science Foundation CHE-1057904Robert A. Welch Foundation F-1018CRI project grant from National Research Foundation of Korea (NRF)Korea government (MSIP) 2009-0081566Chemistr
Anion Receptor Chemistry
No full textAnion recognition plays a critical role in a range of biological processes, and a variety of receptors and carriers can be found throughout the natural world. Chemists working in the area of supramolecular chemistry have created a range of anion receptors, drawing inspiration from nature as well as their own innovative processes. This book traces the origins of anion recognition chemistry as a unique sub-field in supramolecular chemistry, while illustrating the basic approaches currently being used to effect receptor design.The combination of a biological overview and summary of current synthetic approaches provides a coverage that is both comprehensive and comprehensible. First, the authors detail the key design motifs that have been used to generate synthetic receptors and which are likely to provide the basis for further developments. They also highlight briefly some of the features that are present in naturally-occurring anion recognition and transport systems and summarise the applications of anion recognition chemistry. Providing a detailed review for practitioners in the field and a concise introduction to the topic for newcomers, Anion Receptor Chemistry reflects the current state of this exciting research area. Fully-referenced and illustrated in colour, it is a welcome addition to the literature
Synthetic Aminopyrrolic Receptors have Apoptosis Inducing Activity
No full textWe report two synthetic aminopyrrolic compounds that induce apoptotic cell death. These compounds have been previously shown to act as receptors for mannosides. The extent of receptor-induced cell death is greater in cells expressing a high level of high-mannose oligosaccharides than in cells producing lower levels of high-mannose glycans. The ability of synthetic receptors to induce cell death is attenuated in the presence of external mannosides. The present results provide support for the suggestion that the observed cell death reflects an ability of the receptors to bind mannose displayed on the cell surface. Signaling pathway studies indicate that the synthetic receptors of the present study promote JNK activation, induce Bax translocation to the mitochondria, and cause cytochrome c release from the mitochondria into the cytosol, thus promoting caspase-dependent apoptosis. Such effects are also observed in cells treated with mannose-binding ConA. The present results thus serve to highlight what may be an attractive new approach to triggering apoptosis via modes of action that differ from those normally used to promote apoptosis.National Creative Research Initiative program in Korea 2010-0018272U.S. Department of Energy Office of Basic Energy Sciences DOE: DE-FG02-01ER15186Chemistr
Ion Pair-Induced Conformational Motion in Calix 4 Arene-Strapped Calix 4 Pyrroles
No full textIn order to understand the still-poorly understood interplay between calix[4]arene conformations and cation and anion recognition in multicomponent systems, the ion pair receptors 1 and 2 were synthesized. In solution and in the solid state, the calix[4]arene subunit of receptor 1 adopts a cone conformation, while that of 2 interconverts between the cone and the partial cone conformation. These geometric features differ from previous systems where the calix[4]arene moiety was locked in the 1,3-alternate conformation. A combination of H-1 NMR spectroscopic analyses and single crystal X-ray diffraction studies reveal that receptor 1 binds the fluoride and the chloride anion via significantly different binding modes, displaying, for instance, 1 : 1 and 2 : 3 binding stoichiometries with CsF and CsCl, respectively. In the case of 2, the conformation of the calix[4]arene constituent of 2 is highly dependent on the size and quantity of anions present. For example, upon treatment of 2 with the fluoride anion (as both the TBA(+) and Cs+ salts), the calix[4]arene unit coexists as cone and partial cone conformers that are inter-convertible. In the presence of excess CsF, the aromatic rings of the calix[4]arene subunit becomes locked in the pinched cone conformation with the result that an ion pair-mediated coordination polymer is formed. In the presence of excess CsCl, the calix[4]arene unit of 2 adopts only the partial cone conformation stabilized by aryl CH-anion hydrogen bonding interactions. The present systems constitute a rare set of related receptors wherein the effects of conformational changes are so tightly coupled with ion recognition.Office of Basic Energy Sciences, U.S. Department of Energy (DOE) DE-FG02-01ER15186National Research Foundation of The Ministry of Science, ICT & Future Planning in Korea 2009-0081566Chemistr
A Pyrrole-Based Triazolium-Phane with Nh and Cationic Ch Donor Groups as a Receptor for Tetrahedral Oxyanions that Functions in Polar Media
Full text linkThe pyrrole-based triazolium-phane 1(4+)center dot 4BF(4)(-) has been prepared via the tetraalkylation of a macrocycle originally prepared via click chemistry. It displays a high selectivity for tetrahedral oxyanions relative to various test monoanions and trigonal planar anions in mixed polar organic-aqueous media. This selectivity is solvent dependent and is less pronounced in acetonitrile. Theoretical calculations were carried out in with the chloride anion in an effort to understand the influence of solvent on the intrinsic hydrogen bonding ability of the donor groups (pyrrole N-H, benzene C-H and triazolium C-H). The host-guest interactions between receptor 1(4+)center dot 4BF(4)(-) and representative tetrahedral oxyanions were further analysed by H-1 NMR spectroscopy, and the findings proved consistent with the differences in the intrinsic strength of the various H-bond donor groups inferred from the electronic structure calculations carried out in methanol, namely that (CH)(+)-anion interactions are less important in an energetic sense than neutral CH-anion interactions in polar media. Single crystal X-ray diffraction analyses of the mixed salts 1(4+)center dot HP2O73-center dot BF4- and 31(4+)center dot 4H(2)PO(4)(-)center dot 8BF(4)(-) confirmed that receptor 1(4+) can bind the pyrophosphate and phosphate anions in the solid state.Cai, Jiajia, Benjamin P. Hay, Neil J. Young, Xiaoping Yang, and Jonathan L. Sessler. "A pyrrole-based triazolium-phane with NH and cationic CH donor groups as a receptor for tetrahedral oxyanions that functions in polar media." Chemical Science 4, no. 4 (Jan., 2013): 1560-1567.Chemistr
Synthesis and Characterization of A Tetrathiafulvalene-Salphen Actinide Complex
Full text linkA new tetrathiafulvalene-salphen uranyl complex has been prepared. The system was designed to study the electronic coupling between actinides and a redox active ligand framework. Theoretical and experimental methods - including DFT calculations, single crystal X-ray analysis, cyclic voltammetry, NMR and IR spectroscopies - were used to characterize this new uranyl complex.Office of Basic Energy Sciences, U. S. Department of Energy (DOE) DE-FG02-01ER15186Ministry of Education, Science and TechnologyHeavy Element Chemistry Program by the Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences, U.S. Department of EnergyGlenn T. Seaborg InstituteNational Nuclear Security Administration of U.S. Department of Energy DE-AC52-06NA25396Chemistr
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