84028-88-6Relevant articles and documents
Unexpected changes in the population of coordination isomers for the lanthanide ion complexes of DOTMA-tetraglycinate
Kumas, Cemile,Fernando, W. Shirangi,Zhao, Piyu,Regueiro-Figueroa, Martín,Kiefer, Garry E.,Martins, André F.,Platas-Iglesias, Carlos,Sherry, A. Dean
, p. 9297 - 9305 (2016)
Lanthanide complexes with DOTA-tetraglycinate (DOTA-(gly)4) heavily favor the square antiprismatic (SAP) coordination isomer in aqueous solution, a structural feature that has made them useful as water-based paraCEST agents. In an effort to create amide-based paraCEST agents with rapid water exchange rates, we prepared the analogous tetraglycinate complexes with DOTMA, a ligand known to favor the twisted square antiprismatic (TSAP) coordination structures. Unexpectedly, NMR investigations show that the LnDOTMA-(gly)4 complexes, like the LnDOTA-(gly)4 complexes, also favor the SAP isomers in solution. This observation led to density functional theory (DFT) calculations in order to identify the energy terms that favor the SAP structures in lanthanide complexes formed with macrocyclic DOTA- and DOTMA-tetraamide ligands. The DFT calculations revealed that, regardless the nature of the ligand, the TSAP isomers present more negative hydration energies than the SAP counterparts. The extent to which the TSAP isomer is stabilized varies, however, depending on the ligand structure, resulting in different isomeric populations in solution.
Directed Evolution of Artificial Metalloenzymes in Whole Cells
Bloomer, Brandon J.,Chen, Reichi,Clark, Douglas S.,Gu, Yang,Hartwig, John F.,Liu, Zhennan
supporting information, (2021/12/24)
Artificial metalloenzymes (ArMs), created by introducing synthetic cofactors into protein scaffolds, are an emerging class of catalyst for non-natural reactions. Although many classes of ArMs are known, in vitro reconstitution of cofactors and proteins ha
Adaptive Behavior of Dynamic Orthoester Cryptands
Shyshov, Oleksandr,Brachvogel, René-Chris,Bachmann, Tobias,Srikantharajah, Rubitha,Segets, Doris,Hampel, Frank,Puchta, Ralph,von Delius, Max
supporting information, p. 776 - 781 (2017/01/14)
The integration of dynamic covalent bonds into macrocycles has been a tremendously successful strategy for investigating noncovalent interactions and identifying effective host–guest pairs. While numerous studies have focused on the dynamic responses of macrocycles and larger cages to various guests, the corresponding constitutionally dynamic chemistry of cryptands remains unexplored. Reported here is that cryptands based on orthoester bridgeheads offer an elegant entry to experiments in which a metal ion selects its preferred host from a dynamic mixture of competing subcomponents. In such dynamic mixtures, the alkali metal ions Li+, Na+, K+, Rb+, and Cs+exhibit pronounced preferences for the formation of cryptands of certain sizes and donor numbers, and the selection is rationalized by DFT calculations. Reported is also the first self-assembly of a chiral orthoester cryptate and a preliminary study on the use of stereoisomers as subcomponents.