97565-24-7Relevant academic research and scientific papers
Synthesis, characterization and X-ray crystal structures of cyclam derivatives. Part IV. 1,4,8,11-Tetraazacyclotetradecane-5,12-dione and its diprotonated forms
Fremond,Espinosa,Meyer,Denat,Guilard,Huch,Veith
, p. 959 - 966 (2000)
The synthesis, spectroscopic characterization (NMR, IR, MS) and protonation constants of a dioxocyclam derivative, 1,4,8,11-tetraazacyclotetradecane-5,12-dione (1), are described. The crystal structures of the free-base macrocycle and two diprotonated forms, with bromide and perchlorate as counter ions, have been determined by X-ray diffraction studies in order to evaluate the influence of both the secondary amine's protonation state and of the intermolecular hydrogen-bonding interactions on the macrocycle conformation. The spectroscopic, potentiometric and structural data indicate that both secondary amines behave independently from each other, their protonation inducing only limited conformational changes of the macrocyclic framework. In the crystal, the diprotonated species adopt two different [3,4,3,4] diamond-lattice-type conformations as a consequence of intermolecular hydrogen bonds involving the oxo groups and the surrounding anions.
Ferrocene-Cyclam: A redox-active macrocycle for the complexation of transition metal ions and a study on the influence of the relative permittivity on the coulombic interaction between metal cations
Plenio, Herbert,Aberle, Clemens,Al Shihadeh, Youseff,Lloris, Jose Manuel,Martinez-Manez, Ramon,Pardo, Teresa,Soto, Juan
, p. 2848 - 2861 (2007/10/03)
The reaction of 1,1′-ferrocene-bis(methylenepyridinium) salt with 1,4,8,11-tetraazacyclotetradecane-5,12-dione, followed by LiAlH4 reduction results in the formation of FcCyclam. Metal complexes of FcCyclam with M2+ = Co2+, Ni2+, Cu2+, and Zn2+ were synthesized from FcCyclam and the respective metal triflates. The complexation of Cu2+ and FcCyclam in CH3CN is preceeded by a rapid electron transfer, followed by a slower complex formation reaction and a reverse electron transfer. The protonation constants of FcCyclam and the stability constants for the Cu2+ complex of FcCyclam (logK = 9.26(4) for the formation of the [Cu(FcCyclam)]2+ complex) were determined in 1,4-dioxane/water 70:30 v/v, 0.1 mol dm-3, KNO3, 25°C. By using FcCyclam one can selectively sense the presence of Cu2+ ions in the presence of Ni2+, Zn2+, Cd2+, Hg2+, and Pb2+ with a very large ΔE≈200 mV, depending on pH. The X-ray crystal structures of FcCyclam and of complexes with Co2+, Ni2+, Cu2+, and Zn2+ were determined and Fe-M2+ distances obtained: Fe-Co2+ 395.9, Fe-Ni2+ 385.4, Fe-Cu2+ 377.7, and Fe-Zn2+ 369.0 pm. The redox potential of FcCyclam is influenced in a characteristic manner by the complexation of M2+. A linear correlation of 1/r?ΔE [r = distance Fe-M2+ from crystal data, ΔE = E1/2([M(FcCyclam)]2+)-E1/2(FcCyclam)] was found; this is indicative of a mainly Coulomb type interaction between the two metal centers. The nature of the Fe...M2+ interaction was also investigated by determining ΔE in several solvents (mixtures) of different dielectric constants ε. The expected relation of ΔE?1/ε was only found at very high values of ε. At ε 2+ leading to progessively smaller values of ΔE with lowered ε. The dependence of ΔE and ε can be calculated semiquantitatively by combining the Fuoss ion-pairing theory with the Coulomb model. Wiley-VCH Verlag GmbH, 2001.
Copper(n) complexes of the isomeric tetraazamacrocyclic ligands 1,11- And l,8-bis(2-pyridylmethyl)-l,4,8,ll-tetraazacyclotetradecane and of the 1,4,8,1 l-tetraazacyclotetradecane-5,12-dione analogue at neutral and basic pH
Goeta, Andres E.,Howard, Judith A. K.,Maffeo, Davide,Puschmann, Horst,Gareth Williams,Yufit, Dimitrii S.
, p. 1873 - 1880 (2007/10/03)
The regioselective synthesis of the new N,N'-dialkylated tetraazamacrocycle 1,1 l-bis(2-pyridylmethyl)-l,4,8,l 1tetraazacyclotetradecane, L1, has been achieved. The copper(n) complexes of L1 and of the isomeric ligand l,8-bis(2pyridylmethyl)-1,4,8,11-tetr
