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Articles 1 - 12 of 12
Full-Text Articles in Chemistry
Synthesis And Characterization Of Rhenium 2,2′-Pyridylnaphthyridine Metal Complexes, Benjamin F. Solomon
Synthesis And Characterization Of Rhenium 2,2′-Pyridylnaphthyridine Metal Complexes, Benjamin F. Solomon
Honors Theses
Rhenium (Re) is a group 7 heavy 5d transition metal in the same family as manganese (Mn) and technetium (Tc). Re-carbonyl complexes are known to be catalysts for many different kinds of reactions from C-C bond formation to reduction reactions like CO2 reduction (CO2RR)1,2. With this in mind, we have prepared a set of six Re-carbonyl complexes of 2,2′-pyridyl-1,6-naphthyridine (1,6- pynap) and 2,2′-pyridyl-1,8-naphthyridine (1,8-pynap), a redox non-innocent ligand containing a bpy moiety as well as an additional aryl nitrogen binding location at which another metal-ligand bond could form. We have synthesized these complexes as precursors …
A Loose Domain Swapping Organization Confers A Remarkable Stability To The Dimeric Structure Of The Arginine Binding Protein From Thermotoga Maritima, Alessia Ruggiero, Jonathan D. Dattelbaum, Maria Staiano, Rita Berisio, Sabato D'Auria, Luigi Vitagliano
A Loose Domain Swapping Organization Confers A Remarkable Stability To The Dimeric Structure Of The Arginine Binding Protein From Thermotoga Maritima, Alessia Ruggiero, Jonathan D. Dattelbaum, Maria Staiano, Rita Berisio, Sabato D'Auria, Luigi Vitagliano
Chemistry Faculty Publications
The arginine binding protein from Thermatoga maritima (TmArgBP), a substrate binding protein (SBP) involved in the ABC system of solute transport, presents a number of remarkable properties. These include an extraordinary stability to temperature and chemical denaturants and the tendency to form multimeric structures, an uncommon feature among SBPs involved in solute transport. Here we report a biophysical and structural characterization of the TmArgBP dimer. Our data indicate that the dimer of the protein is endowed with a remarkable stability since its full dissociation requires high temperature as well as SDS and urea at high concentrations. In order to elucidate …
Stop Rotating! One Substitution Halts The B19- Motor, Francisco Cervantes-Navarro, Gerarso Martínez-Guajardo, Edison Osorio, Diego Moreno, William Tiznado, Rafael Islas, Kelling J. Donald, Gabriel Merino
Stop Rotating! One Substitution Halts The B19- Motor, Francisco Cervantes-Navarro, Gerarso Martínez-Guajardo, Edison Osorio, Diego Moreno, William Tiznado, Rafael Islas, Kelling J. Donald, Gabriel Merino
Chemistry Faculty Publications
The B19- anion and other boron species have been dubbed ‘Wankel motors’ for the almost barrierless rotation of inner and outer concentric rings relative to each other in these compounds. A single substitution in B19- is shown to shut down the well-established fluxionality in the anion. A carbon atom substituted in the structure to give a neutral CB18 species is shown computationally to enforce bond localization.
Theoretical Design Of Stable Small Aluminium-Magnesium Binary Clusters, Edison Osorio, Alejandro Vasquez, Elizabeth Florez, Fanor Mondragon, Kelling J. Donald, William Tiznado
Theoretical Design Of Stable Small Aluminium-Magnesium Binary Clusters, Edison Osorio, Alejandro Vasquez, Elizabeth Florez, Fanor Mondragon, Kelling J. Donald, William Tiznado
Chemistry Faculty Publications
We explore in detail the potential energy surfaces of the AlxMgy (x, y = 1–4) systems as case studies to test the utility and limitations of simple rules based on electron counts and the phenomenological shell model (PSM) for bimetallic clusters. We find that it is feasible to design stable structures that are members of this set of small Al–Mg binary clusters, using simple electron count rules, including the classical 4n + 2 Hückel model, and the most recently proposed PSM. The thermodynamic stability of the title compounds has been evaluated using several different descriptors, including …
Cbe5e− (E = Al, Ga, In, Tl): Planar Pentacoordinate Carbon In Heptaatomic Clusters, Abril C. Castro, Gerarso Martinez-Guajardo, Thomas Johnson, Jesus M. Ugalde, Yan-Bo Wu, Jose M. Mercero, Thomas Heine, Kelling J. Donald, Gabriel Merino
Cbe5e− (E = Al, Ga, In, Tl): Planar Pentacoordinate Carbon In Heptaatomic Clusters, Abril C. Castro, Gerarso Martinez-Guajardo, Thomas Johnson, Jesus M. Ugalde, Yan-Bo Wu, Jose M. Mercero, Thomas Heine, Kelling J. Donald, Gabriel Merino
Chemistry Faculty Publications
A series of clusters with the general formula CBe5E- (E = Al, Ga, In, Tl) are theoretically shown to have a planar pentacoordinate carbon atom. The structures show a simple and rigid topological framework—a planar EBe4 ring surrounding a C center, with one of the ring Be–Be bonds capped in-plane by a fifth Be atom. The system is stabilized by a network of multicenter σ bonds in which the central C atom is the acceptor, and π systems as well by which the C atom donates charge to the Be and E atoms that encircle it.
Plane And Simple: Planar Tetracoordinate Carbon Centers In Small Moleculesw, Chad Crigger, Bernard K. Wittmaack, Marina Tawfik, Gabriel Merino, Kelling J. Donald
Plane And Simple: Planar Tetracoordinate Carbon Centers In Small Moleculesw, Chad Crigger, Bernard K. Wittmaack, Marina Tawfik, Gabriel Merino, Kelling J. Donald
Chemistry Faculty Publications
A class of neutral 18-electron molecules with planar tetracoordinate carbon (ptC) centers is introduced. We show computationally that when n = 3 the neutral singlet molecule C(BeH)n(BH2)4-n and other isoelectronic (18-valence electron) molecules of main group elements collapse from locally tetrahedral arrangements at the C-center to (near) planar tetracoordinate structures. For C(BeH)3BH2 and C(CH3)(BH2)Li2, for example, the tetrahedral type conformation is not even a minimum on the potential energy surface at the B3PW91, MP2(full), or CCSD levels of theory. The Mg analogue C(MgH)3BH2 …
Shorter Still: Compressing C-C Single Bonds, Gerarso Martinez-Guajardo, Kelling J. Donald, Bernard K. Wittmaack, Miguel Angel Vazquez, Gabriel Merino
Shorter Still: Compressing C-C Single Bonds, Gerarso Martinez-Guajardo, Kelling J. Donald, Bernard K. Wittmaack, Miguel Angel Vazquez, Gabriel Merino
Chemistry Faculty Publications
How short can a C-C single bond get? The bonding in a set of molecules that are related structurally to previously synthesized or theoretically examined systems with short C-C bonds is investigated. According to calculations, a single C-C bond could be compressed to 1.313 A! To the best of our knowledge, this is the shortest single C-C bond reported to date. This shortening is a consequence of a change in the C-C-C bond angle, θ, to minimize strain in the cages and an effort to offset the tension in the surrounding bridges.
Identification And Characterization Of A New Tubulin-Binding, Susan L. Mooberry, Kimberly N. Weiderhold, Sivanesan Dakshanamurthy, Ernest Hamel, Edith J. Banner, Anastasia Kharlamova, Jonathan Hempel, John T. Gupton, Milton L. Brown
Identification And Characterization Of A New Tubulin-Binding, Susan L. Mooberry, Kimberly N. Weiderhold, Sivanesan Dakshanamurthy, Ernest Hamel, Edith J. Banner, Anastasia Kharlamova, Jonathan Hempel, John T. Gupton, Milton L. Brown
Chemistry Faculty Publications
We studied the mechanism of action of 3,5-dibromo-4-(3,4-dimethoxyphenyl)-1H-pyrrole-2-carboxylic acid ethyl ester (JG-03-14) and found that it is a potent microtubule depolymerizer. JG-03-14 caused a dose-dependent loss of cellular microtubules, formation of aberrant mitotic spindles, accumulation of cells in the G2/M phase of the cell cycle, and Bcl-2 phosphorylation. These events culminated in the initiation of apoptosis, as evidenced by the caspase 3-dependent cleavage of poly(ADP-ribose) polymerase (PARP). JG-03-14 has antiproliferative activity against a wide range of cancer cell lines, with an average IC50 value of 62 nM, and it is a poor substrate for transport …
Efficient And General Synthesis Of Novel Β-Polyfluoroalkoxy Vinamidinium Salts, Koichiro Kase, Mitsuyoshi Katayama, Takashi Ishihara, Hiroki Yamanaka, John T. Gupton
Efficient And General Synthesis Of Novel Β-Polyfluoroalkoxy Vinamidinium Salts, Koichiro Kase, Mitsuyoshi Katayama, Takashi Ishihara, Hiroki Yamanaka, John T. Gupton
Chemistry Faculty Publications
Novel β-polyfluoroalkoxy vinamidinium salts 3 and/or 4 were synthesized in good yields by the reaction of N-(2- polyfluoroalkoxy-3 ,3-difluoro-1-propenyI)trimethylammonium iodides (2), prepared from N-(2,3,3-trifluoro-1-propenyl)trimethylammonium iodide (1), with secondary amines in MeCN at 70 °C for 1 h. The salts were also obtainable in comparable yields by the one-pot reaction of 1 with sodium polyfluoroalkoxide followed by treatment with amines.
Method For Direct Preparation For 1,2,4-Triazole From Hydrazine And Formamide, Harris E. Petree, Joseph R. Pociask, John T. Gupton
Method For Direct Preparation For 1,2,4-Triazole From Hydrazine And Formamide, Harris E. Petree, Joseph R. Pociask, John T. Gupton
Chemistry Faculty Publications
Process for the preparation of 1,2,4-triazole comprises contacting hydrazine or its aqueous solutions with at least about 2.5 moles of formamide at a temperature of 140° to 210° C. and then recovering the resultant 1,2,4- triazole in yields of 92-98% with 94-98% purity. The formamide is maintained in an excess over about the 2.5 molar amount consumed in the reaction with the hydrazine. Recovery steps for isolating the 1,2,4-triazole are disclosed.
A Process For The Production Of 2-Alkyl Or 2-Cycloalkyl-4-Methyl-6-Hydroxypyrimidines, Joseph T. Blackwell Iii, John T. Gupton, Teruko U. Miyazaki, James B. Nabors, Joseph R. Pociask
A Process For The Production Of 2-Alkyl Or 2-Cycloalkyl-4-Methyl-6-Hydroxypyrimidines, Joseph T. Blackwell Iii, John T. Gupton, Teruko U. Miyazaki, James B. Nabors, Joseph R. Pociask
Chemistry Faculty Publications
Production of 2-alkyl- or cycloalkyl-4-methyl-6- hydroxypyrimidines by first neutralizing an alkyl imidate ester hydrochloride with a base in the presence of a water-immiscible solvent for the alkyl imidate ester to be freed thereby; condensing the alkyl imidate ester with diketene to form an oxazinone intermediate, which is then reacted in organic solution with gaseous ammonia and recovering the desired substituted 6-hydroxypyrimidine.
Photochemical Rearrangements Of 6/5 -Fused Cross-Conjugated Cyclohexadiensnes In Protic Solvents, Drury Caine, John T. Gupton, Ko Ming, William J. Powers Iii
Photochemical Rearrangements Of 6/5 -Fused Cross-Conjugated Cyclohexadiensnes In Protic Solvents, Drury Caine, John T. Gupton, Ko Ming, William J. Powers Iii
Chemistry Faculty Publications
Irradiation of the ring A unsubstituted 6/5-fused cross-conjugated cyclohexadienone (1a) and its 2-methyl derivative (1b) in methanolic acetic acid yields, in addition to other products, novel tricyclononane derivatives which have been assigned the structures (3a) and (3b).