Academic literature on the topic 'Sarcophagine cage'

Structure determinations for some Co(iii) sarcophagine complexes show that there is no evidence that the H-bonding involving the NH centres of the complex cations is influenced by electronic effects due to the substituents.

Template syntheses based on tris (ethane-1,2-diamine)cobalt(III) lead to cobalt(III) complexes of cage hexamines of the ' sarcophagine ' type ( sarcophagine = sar = 3,6,10,13,16,19- hexaazabicyclo [6.6.6] icosane ) rapidly and in high yield. Reduction of these species to their cobalt(II) forms enables the ligands to be removed in concentrated acids at elevated temperatures, and in hot aqueous solutions containing excess cyanide ion. The free sarcophagine and 1,8-diaminosarcophagine [(NH2)2sar or diamsar] ligands are strong bases, accepting up to four and five protons, respectively, in aqueous solution. In chloride medium, I = 1.0, at 298 K, pK1 = 11.95, pK2 = 10.33, pK3 = 7.17, pK4 ≈ 0 for sarcophagine , and pK1 = 11.44, pK2 = 9.64, pK3 = 6.49, pK4 = 5.48, pK5 ≈ 0 for diaminosarcophagine , with very similar values being found for triflate medium. Crystal structure determinations for both free bases, the chloride, sulfate, perchlorate and nitrate salts of diamsar , the complex of zinc chloride with sar, and the magnesium nitrate complex with diamsar show remarkably small variations in the cavity defined by the bicyclic ligands, though relatively subtle bond length and bond angle changes can be rationalized in terms of the effects of proton and metal ion binding. Exhaustive methylation of sarcophagine produces the highly lipophilic, hexatertiary base hexamethylsarcophagine , which, in the solid state, adopts quite different conformations and nitrogen-atom configurations to those of sar itself. All the ligands rapidly form metal ion complexes of generally exceptional kinetic and thermodynamic stability.

Control of redox properties of cobalt macrobicyclic hexaamine (cage) complexes by substituent modification is important for their use as electron-transfer agents, and the resultant derivatives can also change the lipophilicity of the complexes for a variety of biological and other applications. Such derivatization is also important for incorporating cage complexes into a range of redoxactive conjugates. Here, the derivatization of the amine groups in the 1 and 8 positions of [Co(sar)]3+ (sar = sarcophagine = 3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosane) are reported. The synthesis and properties of methylamide (from the reactions with acetic anhydride), arylimine (from Schiff base reactions), benzylamine, phthalimido, and tosylate derivatives are described. These reactions provide synthons that have the potential to act as precursors for building a range of conjugates containing metal cage complexes, including dimers. The effects of the substituents on the ligand conformations, which affect other chemical and physical properties of the cage complexes, are discussed.

The synthesis and single-crystal X-ray structure determination of the title compound are described. Crystals are monoclinic, P 21, a 16.164(9), b 8.277(3), c 8.829(4) Ǻ, β 102.86(4)°, Z 2; 2666 independent 'observed' diffractometer data [I > 3σ(I)] were refined to a residual of 0.045. The cation is unusual amongst complexes of sarcophagine (3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosane) cage amines in adopting a lel2ob conformation, seemingly in response to hydrogen bonding/crystal packing forces. In consequence, unlike the tetranitrate analogue in which Ni-N bond distances are dispersed over a narrow range (2.097(5)-2.119(5) Ǻ; mean 2.109 Ǻ], the coordination sphere is more distorted with one pair of Ni-N distances, cis to each other, being short at 2.081(5) and 2.086(5) Ǻ, while the other four are long, ranging from 2.116(5) to 2.135(5) Ǻ, the mean of this array being 2.111 Ǻ.

The ligand sarcophagine ( sar = 3,6,10,13,16,19-hexaazabicyclo[6.6.6] icosane ) rapidly reacts with [ Mn (OH2)6]2+ to form the nearly colourless [ Mn ( sar )]2+ ion, which can readily be oxidized to the bright orange [Mn ( sar )]3+ ion (E°′+0.53 V v. n.h.e. in 0.1 mol l-1 CF3SO3H at 295 K). A single-crystal structure determination on [ Mn ( sar )](NO3)3, space group I 42d, a 15.549(6), c 19.014(6) Ǻ, R 0.051, Rw 0.049 for 608 'observed' reflections, shows the coordination geometry of the manganese(III) ion, with site symmetry 2, to be subject to a Jahn-Teller distortion, giving three pairs of Mn -N bond lengths of 2.18(1), 2.13(1) and 2.08(1)Ǻ. The [ Mn ( sar )]3+ ion is stable in strongly acidic aqueous solutions, but in solutions of pH > 3 undergoes deprotonation and subsequent disproportionation reactions. The manganese(II) complex ion is less stable in acidic solutions, undergoing hydrolysis at a rate showing a first-order dependence on both proton and chloride ion concentrations. Both [ Mn ( sar )]2+ and [ Mn ( sar )]3+ can be obtained in chiral forms, and the rate constant for electron self-exchange obtained by polarimetric measurements on solutions of mixtures of [ Mn ( sar )]2+ and [ Mn ( sar )]3+ of opposite chirality is 30 dm3 mol-1s-1 at 298 K, I = 0.1 M.

[Formulae and special characters can only be approximated here. Please see the pdf version of the Abstract for an accurate reproduction.] The kinetics for outer-sphere electron transfer between a series of cobalt(II) poly-aza cage ligand complexes and the iron(III) sarcophagine-type hexa-aza cage complex, [Fe(sar)]3+ (sar = 3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosane), in aqueous solution have been investigated and the Marcus correlation is used to deduce the electron self-exchange rate constant for the [Fe(sar)]3+/2+ couple from these cross-reactions. The deduced electron self-exchange rate constant is in relatively good agreement with the experimentally determined rate constant (k ex calc = 4 ´ 10 5 M -1 s -1 ; k ex obs = 8 ´ 10 5 M -1 s -1 ). The successful application of the Marcus correlation to the electron transfer reactions of the Fe cage complex is consistent with the trend for the Co, Mn, Ni and Ru cage complexes which all follow the pattern of outer-sphere electron transfer reactivity expected from the Marcus-Hush formalism. A comparison of predictions based on the Marcus correlation with the experimentally determined kinetics of an extended series of cross reactions involving cobalt cage complexes with low-spin-high-spin cobalt(III)/(II) couples shows that electron transfer reactions involving large spin changes at the metal centre are not necessarily anomalous in the context of the adiabatic Marcus-Hush formalism. The results of this study also show that for suitable systems, the Marcus correlation can be used to reliably calculate the rates of outer-sphere electron transfer cross-reactions, with reaction free-energy changes spanning the range -6 to -41 kJ mol -1 and many different combinations of initial electronic configurations. Together, these results provide a coherent and internally consistent set of experimental data in support of the Marcus-Hush formalism for outer-sphere electron transfer. The results with the caged metal-ion systems also highlight the special nature of the mechanism of electron transfer in reactions of metal-aqua ions. ¶ A new range of symmetrically disubstituted hexa-aza sarcophagine-type cage ligand complexes are prepared in this study by the base-catalysed co-condensation of formaldehyde and a-methylene aliphatic aldehydes with cobalt(III) tris(1,2-diamine) precursors in acetonitrile solution. Encapsulation reactions based on the condensation of the weak carbon di-acids propanal and decanal with formaldehyde and the cobalt(III) tris(1,2-diamine) precursors, [Co(en)3 ] 3+ (en = 1,2-ethanediamine) and D-lel3 -[Co((R, R)-chxn)3 ] 3+ (chxn = 1,2-cyclohexanediamine), yield unsaturated cobalt(III) cage complexes with an endo-cyclic imine function in each cap. The Co III -coordinated endo-cyclic imine units of the cage ligands are reactive electrophiles that are readily reduced by the BH4 - ion to give the corresponding symmetrically di-substituted hexaamine macrobicyclic cage ligands. The nitromethane carbanion is also shown to add at the endo-cyclic imine function to yield a novel nitromethylated cage ligand complex. The latter reaction introduces a new method for the regioselective functionalisation of cage ligands at sites removed from the more commonly substituted bridgehead positions. The capping of cobalt(III) tris(1,2-diamine)-type complexes with weak CH-acids developed in this study introduces a new and more direct route to symmetrically di-substituted cage ligand complexes. ¶ A new range of cobalt(III) surfactant cage complexes, with linear octyl, dodecyl and hexadecyl hydrocarbon chains built directly into the bridgehead structure of the cage ligand, have been prepared by the base catalysed co-condensation of formaldehyde and long chain aliphatic aldehydes with the tripodal cobalt(III) hexaamine complex, [Co(sen)]3+ (sen = 4,4',4''-ethylidynetris(3-azabutan-1-amine)), in acetonitrile solution. Chiral surfactant cage complexes are obtained by capping reactions beginning with the optically pure L-[Co(sen)]3+ precursor complex. The cobalt(III) cage complexes with octyl to hexadecyl substituents are surface active and reduce the surface tension of water to levels approaching those of organic solvents. The dodecyl substituted cage complex forms micelles in aqueous solution when the concentration of cage complex is > 1 ´ 10 -3 mol dm -3 at 25 °C. The cobalt(III) cage head-group of these surfactants undergoes an electrochemically reversible one-electron reduction to the corresponding cobalt(II) cage complex. The reduction potential of the surfactant head group can be tuned to more positive potentials by replacing the bridgehead hydrocarbon chain substituent with an ether linked hydrocarbon chain. The cobalt(III) surfactant-cage complexes are biologically active and are lethal to the tapeworm Hymenolepis diminuta, and the vaginal parasites, Trichomonas vaginalis and Tritrichomonas foetus. The surfactant cage complexes also cause lysis in red-blood cell membranes at concentrations as low 10 -5 mol dm -3 . Their biological activity is linked to the high head-group charge (3+) and size which cause distortions in biological membranes when the membrane is treated with these molecules. The combination of the chemically reversible outer-sphere redox properties of the cobalt cage head-groups and the chirality of the head group introduces a new and possibly unique series of chiral surfactant coordination complexes which are also redox active. ¶ The chiral carboxylic-acid ionophore, lasalocid A, has been used to promote the selective supramolecular transport and extraction of cobalt(III) hexa-aza cage cations and related tripodal cobalt(III) complexes. The conjugate base anion of lasalocid A forms stoichiometric outer-sphere complexes with the cobalt(III) cage and tripod complexes. These outer-sphere complexes are highly lipophilic and partition strongly from water into a chloroform phase. The extraction of the dissymmetric cobalt(III) complexes by the chiral polyether anion is enantioselective for many systems and results in the partial resolution of initially racemic complexes in the aqueous phase. A strong structural preference was demonstrated by the ionophore for symmetrically disubstituted cobalt(III) hexa-aza cage cations with a D-absolute configuration of the ligand about the metal-ion and an R configuration of the coordinated secondary amine N-H groups. The lasalocid A anion was also shown to promote the transport of the complexes, intact, across a chloroform bulk-liquid membrane against an NH4 + concentration gradient. The transport of the cobalt(III) complexes was also enantioselective and resulted in partial resolution of the initially racemic aqueous phase. The most efficiently transported enantiomer of each complex was also the most efficiently extracted isomer in all systems examined, consistent with a transport process limited by interfacial diffusion. The magnitude of the enantiomer separation obtained in some systems was sufficient to indicate that lasalocid A mediated extraction and transport may become a practical method for the resolution of particular types of kinetically-inert chiral metal-amine complexes.

The kinetics for outer-sphere electron transfer between a series of cobalt(II) poly-aza cage ligand complexes and the iron(III) sarcophagine-type hexa-aza cage complex, [Fe(sar)]3+ (sar = 3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosane), in aqueous solution have been investigated and the Marcus correlation is used to deduce the electron self-exchange rate constant for the [Fe(sar)]3+/2+ couple from these cross-reactions. The deduced electron self-exchange rate constant is in relatively good agreement with the experimentally determined rate constant (k ex calc = 4 ´ 10 5 M -1 s -1 ; k ex obs = 8 ´ 10 5 M -1 s -1 ). The successful application of the Marcus correlation to the electron transfer reactions of the Fe cage complex is consistent with the trend for the Co, Mn, Ni and Ru cage complexes which all follow the pattern of outer-sphere electron transfer reactivity expected from the Marcus-Hush formalism. A comparison of predictions based on the Marcus correlation with the experimentally determined kinetics of an extended series of cross reactions involving cobalt cage complexes with low-spin-high-spin cobalt(III)/(II) couples shows that electron transfer reactions involving large spin changes at the metal centre are not necessarily anomalous in the context of the adiabatic Marcus-Hush formalism. The results of this study also show that for suitable systems, the Marcus correlation can be used to reliably calculate the rates of outer-sphere electron transfer cross-reactions, with reaction free-energy changes spanning the range -6 to -41 kJ mol -1 and many different combinations of initial electronic configurations. Together, these results provide a coherent and internally consistent set of experimental data in support of the Marcus-Hush formalism for outer-sphere electron transfer. The results with the caged metal-ion systems also highlight the special nature of the mechanism of electron transfer in reactions of metal-aqua ions. ¶ ...

Coordination of transition metals to peptides, either through the incorporation of unnatural chelating groups or amino acid ligating side-chains, expands the utility of peptides for biological studies. The first part of this project describes induction of α-helical secondary structure in pentapeptides upon side-chain coordination of inert transition metal ions. The second part of this project describes the syntheses of biologically active peptide species that contain a macrobicyclic hexaamine ligand that can complex radioactive metal ions for diagnostic imaging purposes.
Short peptide sequences do not form thermodynamically stable α-helices in water. The capacity of two metal clips, cis-[Ru(NH3)4(solvent)2]2+ and cis [Pd(en)(solvent)2]2+ to induce α-helicity in peptides that are five amino acids long, Ac HARAH NH2 and Ac MARAM-NH2 has been explored. In all cases at pH < 5, the metal ions bind to the side-chains of amino acid residues at positions i, i+4 of the pentapeptides resulting in formation of bidentate macrocyclic species. Circular dichroism and 1H nuclear magnetic resonance data indicate that the metal complexes of Ac-MARAM-NH2 are highly α helical in water, and in the most spectacular case, coordination of Ac-MARAM-NH2 to cis-[Ru(NH3)4(solvent)2]2+ results in up to 80% α-helicity. In contrast, metal complexes of Ac-HARAH-NH2 exhibit significantly less α-helicity in water.
64Cu-radiolabelled peptides have been investigated for their ability to target specific tissue or cell types. These peptides require a chelating group that binds copper ions strongly. Macrobicyclic hexaamine ligands, based on the compound commonly referred to as “sarcophagine”, have demonstrated extremely high stability under biological conditions. Here we describe the synthesis of diaminosarcophagine chelators with carboxylate groups for conjugation to peptides. These new chelators have been attached to the N-terminus or lysine side-chain of biologically-active peptides, including Tyr3 octreotate, Lys3-bombesin and an integrin targeting peptide. Spectroscopic and voltammetric studies of these species suggest that the conjugated sarcophagine group retains the high metal binding affinity and structural properties of the parent species, diaminosarcophagine. These are among the first sarcophagine-peptide compounds that have been properly characterised. The new sarcophagine-peptide conjugates can be easily radiolabelled with 64Cu2+ over a wide pH range at ambient temperature.

This chapter discusses the importance of digital data capture techniques such as digital photogrammetry for expanding access to texts carved on Egyptian sarcophagi by creating collections of digitized large mortuary objects. Such large objects are often stored in museum warehouses and not easily shared with scholars and the public. By providing a thorough explanation of the digital techniques and results of the “Book of the Dead in 3D” project at UC Berkeley, this chapter highlights the significance of conducting text analysis on the 3D models of the coffins by creating interactive annotations--including text transcription and translation of the magical spells--on the digital models themselves. This kind of embedded metadata is critical to scholars of Egyptology. The case study presented--the sarcophagus of Psamtik in the collections of the Phoebe Hearst Museum at Berkeley--describes in detail the technique of digital photogrammetry combined with custom programming to create the annotated 3D models.

In Southern Cyprus the principal site of interest is Paphos, where the Apostle Paul encountered the Roman governor of Cyprus, Sergius Paulus. But other fine sites of interest range from Paphos to Larnaca, a distance of approximately 80 miles. Since there are airports in both locations and ferries arrive at Limassol, a visit might begin at any one of these places. In any case, with an early start it is possible to make a round trip between Paphos and Larnaca in one day and see the principal sites. A much easier itinerary, however, involves seeing the sites in the Paphos area on one day and the sites in Larnaca on another day, along with those between Paphos and Larnaca. The two sites in the south referred to in the Bible are Paphos and Kition (Kittim), which is mentioned in the Hebrew scriptures. Related sites include St. Paul’s Pillar, the Catacombs of Agia Solomoni, the Tombs of the Kings, Paleopaphos, the Temple of Aphrodite, Kourion, the Temple of Apollo, and the Church of St. Lazarus, as well as several museums. The route below begins at Larnaca and proceeds toward Paphos, since that is the direction Paul and his companions traveled. At one time, Kition was one of the greatest naval powers in the Mediterranean, and its mercenaries even served in the deserts of southern Judea. Today its ruins still suggest the might of this ancient city. The site of ancient Kition, known in the Bible as Kittim, is located in the modern city of Larnaca. In the construction of Larnaca, whose name likely came from the Greek word for sarcophagus (larnax), or coffin, many sarcophagi were unearthed from ancient Kition. Larnaca was the location of a settlement of Mycenaeans as early as the 13th century B.C.E. Later abandoned, the site was rebuilt around 1200 B.C.E. by Achaean refugees following the destruction of the great Mycenaean centers of mainland Greece. A second wave of immigrants arrived about 1150 B.C.E. The original mud-brick city walls were rebuilt in the 12th century B.C.E. with cyclopean stones, huge rectangular ashlar blocks. After an earthquake in 1075 B.C.E., the city was resettled closer to the sea.

A particularly baroque literary appearance of the Kentucky Mummy highlights the transformation of public perceptions of indigenous antiquities in the United States in the Civil War decade. An imaginary romance of Mammoth Cave, Legends of the South (Smith 1869), describes a mysterious, annual journey of a “venerable Indian” down into the cavern. Ultimately the old man disappears into its depths, never to return. Decades later the author pursues the subterranean trail, encountering marvels that include the warning Siste viator—“Stop, traveler”— chalked on the cave wall. Nearby he finds the deceased elder, reduced to a “mummy-like dessication” clad in deerskin. Armed with an amulet taken from the body he pushes onward, ultimately entering a vast sepulcher in which . . . lay the warrior tribe, in their panoply complete. Supine—with their hands crossed upon their breasts, with their faces turned upward, as if acknowledging the presence of a superior being, they lay, like the marble effigies of the knights of old upon their sarcophagi. . . . In this catacomb the author is haunted by a ghostly “Sachem” who chides: “Are you not satisfied that your cruel warfare has exterminated us from the surface of the earth? Must you follow us to these chambers of death to scatter our ashes?” The supernatural figure then describes the wars of his dead people, prophesying that those events would be repeated in post-Civil War United States. “Nations from the rising sun shall make war upon the conquerors,” he pronounces “and then shall the Southern panther rise from his lair, and avenge his wrongs.” This subterranean tale amplified the myriad accounts of the Kentucky Mummy—a discovery two generations in the past by that time. By the mid-nineteenth century such visions of indigenous antiquity were increasingly commonplace, but the linkage between these histories and current events indicate increasingly deep associations with the American landscape. It was not simply abstract indigenous history that was being co-opted, however, but the material legacy of that experience—the ruins and artifacts that were ubiquitous in the increasingly populated countryside.

Introdução: A entomologia forense é a ciência que estuda a aplicação de insetos, ácaros e outros artrópodes para fins legais. Nessa perspectiva, o uso de insetos necróticos como indicadores biológicos nos estágios de decomposição cadavérica constitui auxílio importante na investigação pericial, principalmente na estimativa do período pós-morte em vítimas de violência e na suposição do local de óbito. No Brasil, há expressiva biodiversidade de fauna cadavérica e, dadas as suas dimensões territoriais, cabe aos profissionais da perícia criminal o reconhecimento das entomofaunas regionais, das condições ambientais e físicas locais para atender ao interesse médico-legal. Objetivos: Sendo assim, busca-se analisar a contribuição da fauna necrótica brasileira na prática pericial. Material e métodos: Para isso, utilizou-se pesquisa bibliográfica, através de ferramentas digitais de busca por artigos científicos em inglês e português, como Google Scholar e Scielo, entre os anos de 2014 e 2021. Resultados: Com isso, constata-se que a integração da entomologia forense na atividade pericial propicia maior acurácia na averiguação de informações criminais, visto que insetos necróticos têm parte do seu ciclo de vida em tecidos em decomposição. Dessa forma, os principais insetos de interesse da medicina legal são os dípteros, como Sarcophagidae, Muscidae e Calliphoridae, considerados os primeiros a encontrar o corpo e a depositar seus ovos, indicando estágios iniciais do processo de decomposição; seguidos pelos coleópteros, como Scrabaeidae, Silphidae e Dermestidae, que colonizam o cadáver nos estágios finais de putrefação, sendo utilizados quando os líquidos e tecidos moles corporais são inviáveis. Logo, os insetos são fundamentais na determinação do intervalo post-mortem, identificação de deslocamento do corpo, presença de substâncias tóxicas e drogas, ocorrência de estupro, através de amostra de sêmen, além de reconhecimento da vítima, por meio de DNA incorporado pelos insetos na ingestão de tecido cadavérico. Conclusão: Por fim, infere-se que o emprego da entomologia forense na investigação de crimes fornece dados de credibilidade ao âmbito jurídico. Na realidade nacional, apesar do crescimento do número de profissionais da área nos últimos anos, essa temática ainda requer estudos, com fins a aprimorar métodos e torná-los mais precisos na elucidação de crimes.