Preparation of a Cobalt(II) Cage: An Undergraduate Laboratory Experiment That Produces a ParaSHIFT Agent for Magnetic Resonance Spectroscopy

Burns, Patrick J.; Tsitovich, Pavel B.; Morrow, Janet R.

doi:10.1021/acs.jchemed.5b00818

Cited by 19 publications

(15 citation statements)

References 30 publications

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“…CEST spectra,, plotted as the percent decrease in water proton magnetization as a function of presaturation pulse frequency were recorded for [Ni( L5 )] 2+ , [Ni( L2 )] 2+ , and [Ni( L3 )] 2+ (Figure , Figure S18 and Figure S19). No CEST effect could be detected for [Ni( L1 )] 2+ .…”

Section: Resultsmentioning

confidence: 99%

Nickel(II) Complexes as Paramagnetic Shift and paraCEST Agents

et al. 2018

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Five Ni II macrocyclic complexes are studied as water proton shift agents and as paraCEST agents (paraCEST = paramagnetic chemical exchange saturation transfer) for MRI applications. The five macrocycles have amide and/or alcohol pendent groups with either tetraaza-or triazamacrocycles including 1,1′,1′′-(1,4,7-triazonane-1,4,7-triyl)tris(propan-2-ol) (L1), 1,1′,1′′,1′′′-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetra)tetrakis(propan-2-ol) (L2), 1,1′,1′′, 1′′′-(1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetrayl)tetrakis(propan-2-ol) (L3), 2,2′,2′′-(1,4,7triazonane-1,4,7-triyl)triacetamide (L4), or 2,2′-(7-benzyl-1,4,7triazonane-1,4-diyl) diacetamide (L5). Solution magnetic moments are consistent with paramagnetic Ni II complexes. The complexes are characterized by pH-potentiometric titrations to

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Section: Resultsmentioning

confidence: 99%

Nickel(II) Complexes as Paramagnetic Shift and paraCEST Agents

et al. 2018

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“…Co(II) paraCEST agents reported to date typically are encapsulated by a macrocyclic ligand and have exchangeable amide NH, alcohol OH, or heterocyclic NH protons. ,− There are no examples of exchangeable water ligands on Co(II) complexes that produce CEST peaks, to the best of our knowledge. In contrast, Ln(III) paraCEST agents frequently have a slowly exchanging water ligand that gives rise to a CEST peak .…”

Section: Introductionmentioning

confidence: 98%

Inner-Sphere and Outer-Sphere Water Interactions in Co(II) paraCEST Agents

et al. 2018

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High-spin Co(II) complexes are promising for development as paraCEST agents (paraCEST = paramagnetic chemical exchange saturation transfer) for magnetic resonance imaging applications. The first examples of Co(II) paraCEST agents with bound water ligands are presented here. Four Co(II) macrocyclic complexes based on 1,4,7-triazacyclononane and containing either pendent alcohol or pendent amide groups were prepared. Two of the macrocycles encapsulate the Co(II) and contain no water ligands as shown by X-ray crystallographic studies, and two complexes have macrocycles with only five ligand donor groups to leave an open coordination site for bound water. The ionization of alcohol, water, or amide groups in the complexes was characterized by using pH potentiometry. These data show that one of the complexes has a readily deprotonated group with a pK close to 6, which is assigned as an alcohol pendent. Amide pendents deprotonate at high pH (>8), and the water ligands of the Co(II) complexes are not deprotonated at neutral pH. All complexes produce CEST peaks through either alcohol OH or amide NH proton exchange. The water ligands exchange too rapidly to produce a CEST effect as shown by variable-temperature O NMR spectroscopy studies. The complexes with available coordination sites for inner-sphere water ligands produce large paramagnetic shifts and broadening of theO resonances of bulk water, whereas the encapsulated complexes show much less shifting and broadening of O resonances. All complexes produce substantial paramagnetic shifts of theH resonances of bulk water, which is promising for the development of supramolecular CEST agents.

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“…In the present work, the temperature dependence of paramagnetic chemical shifts of complex [Co(DTPA)] 3is studied and the prospects of its use as an NMR thermal sensor for local temperature measurements are estimated. of CSs is about 1.3 ppm/K [19]; a close value (1.38 ppm/K) was also obtained for complex [Co(diNOSar)]Cl 3 [4]. The authors of [20] reported an unprecedented value of 15 ppm/K for the hydride proton in complex t-Bu (PNP) with iron, even though this complex cannot be currently considered as a temperature-sensitive MRI probe.…”

Section: Introductionmentioning

confidence: 69%

“…The stronger the temperature dependence of the chemical shift, the more accurately the temperature can be determined by analyzing the signal's position. Based on this principle, a number of MRI procedures have been developed for the diagnosis of inflammation and oncological diseases [2][3][4][5]. Complexes of transition 3d-block elements with polyaminopolycarboxylates (such as EDTA, DTPA, DOTA) have been considered as the most promising materials for such applications.…”

Section: Introductionmentioning

confidence: 99%

NMR STUDY OF THE TEMPERATURE DEPENDENCE OF PARAMAGNETIC CHEMICAL SHIFTS OF [Co(DTPA)]3–

Zapolotsky

Babailov

2021

J Struct Chem

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Temperature dependences of paramagnetic chemical shifts in complex [Co(DTPA)] 3are studied by NMR.It is established that the maximal temperature sensitivity of chemical shifts d(δ exp )/dT is 0.68 ppm/K.Taking into account the half-width of the signal (|CT|/W = 0.51 K −1 ), the NMR shifts of the studied complex show high temperature sensitivity in the series of complexes of paramagnetic d-block elements. Complex [Co(DTPA)] 3can be considered as a promising compound for the design of temperature sensitive NMR probes to determine local temperature in aqueous environments and for advanced MRI diagnostics.

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Preparation of a Cobalt(II) Cage: An Undergraduate Laboratory Experiment That Produces a ParaSHIFT Agent for Magnetic Resonance Spectroscopy

Cited by 19 publications

References 30 publications

Nickel(II) Complexes as Paramagnetic Shift and paraCEST Agents

Nickel(II) Complexes as Paramagnetic Shift and paraCEST Agents

Inner-Sphere and Outer-Sphere Water Interactions in Co(II) paraCEST Agents

NMR STUDY OF THE TEMPERATURE DEPENDENCE OF PARAMAGNETIC CHEMICAL SHIFTS OF [Co(DTPA)]3–

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