Six, Seven or Eight Coordinate Fe(II) , Co(II) or Ni(II) Complexes of Amide-Appended Tetraazamacrocycles for ParaCEST Thermometry.
Fe(II) , Co(II) and Ni(II) complexes of two tetraazamacrocycles (1,4,8,11-tetrakis(carbamoylmethyl)-1,4,8,11-tetraazacyclotetradecane (L1) and 1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane (L2) show promise as paraCEST agents for registration of temperature (paraCEST=paramagnetic chemical exchange saturation transfer). The Fe(II) , Co(II) and Ni(II) complexes of L1 show up to four CEST peaks shifted ≤112 ppm, whereas analogous complexes of L2 show only a single CEST peak at ≤69 ppm. Comparison of the temperature coefficients (CT ) of the CEST peaks of [Co(L2)](2+) , [Fe(L2)](2+) , [Ni(L1)](2+) and [Co(L1)](2+) showed that a CEST peak of [Co(L1)](2+) gave the largest CT (-0.66 ppm (o) C(-1) at 4.7 T). NMR spectral and CEST properties of these complexes correspond to coordination complex symmetry as shown by structural data. The [Ni(L1)](2+) and [Co(L1)](2+) complexes have a six-coordinate metal ion bound to the 1-, 4-amide oxygen atoms and four nitrogen atoms of the tetraazamacrocycle. The [Fe(L2)](2+) complex has an unusual eight-coordinate Fe(II) bound to four amide oxygen atoms and four macrocyclic nitrogen atoms. For [Co(L2)](2+) , one structure has seven-coordinate Co(II) with three bound amide pendents and a second structure has a six-coordinate Co(II) with two bound amide pendents.
Department of Chemistry, University at Buffalo, State University of New York, Amherst, NY 14260-3000 (USA).
Abiola O
AO
Olatunde
Department of Chemistry, University at Buffalo, State University of New York, Amherst, NY 14260-3000 (USA).
Christopher J
CJ
Bond
Department of Chemistry, University at Buffalo, State University of New York, Amherst, NY 14260-3000 (USA).
Sarina J
SJ
Dorazio
Department of Chemistry, University at Buffalo, State University of New York, Amherst, NY 14260-3000 (USA).
Jordan M
JM
Cox
Department of Chemistry, University at Buffalo, State University of New York, Amherst, NY 14260-3000 (USA).
Jason B
JB
Benedict
Department of Cell Stress Biology, Roswell Park Cancer Institute, Buffalo, NY 14263 (USA).
Michael D
MD
Daddario
Department of Cell Stress Biology, Roswell Park Cancer Institute, Buffalo, NY 14263 (USA).
Joseph A
JA
Spernyak
Department of Chemistry, University at Buffalo, State University of New York, Amherst, NY 14260-3000 (USA). jmorrow@buffalo.edu.
Janet R
JR
Morrow
D000081:Acetamides / Q000737:chemistry*; D000577:Amides / Q000737:chemistry*; D003287:Contrast Media / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006571:Heterocyclic Compounds / Q000737:chemistry*; D006573:Heterocyclic Compounds, 1-Ring / Q000737:chemistry*; D008024:Ligands; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008670:Metals / Q000737:chemistry*; D015394:Molecular Structure
C522450:1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane; C000608157:1,4,8,11-tetrakis(carbamoylmethyl)-1,4,8,11-tetraazacyclotetradecane; D000081:Acetamides; D000577:Amides; D003287:Contrast Media; D056831:Coordination Complexes; D006571:Heterocyclic Compounds; D006573:Heterocyclic Compounds, 1-Ring; D008024:Ligands; D008670:Metals; C024560:cyclam
NMR spectroscopy; chemical exchange saturation transfer; imaging agents; macrocycles; magnetic resonance imaging