Dataset Information

A Bronsted Acidic Gallium Hydride: Facile Interconversion of NNNN-Macrocycle Supported [Ga^I ]⁺ and [Ga^III H]².

ABSTRACT: Protonolysis of [Cp*M] (M=Ga, In, Tl) with [(Me₄ TACD)H][BAr₄ ^Me ] (Me₄ TACD=N,N',N'',N'''-tetramethyl-1,4,7,10-tetraazacyclododecane; [BAr₄ ^Me ]^- =[B{C₆ H₃ -3,5-(CH₃ )₂ }₄ ]^- ) provided monovalent salts [(Me₄ TACD)M][BAr₄ ^Me ], whereas [Cp*Al]₄ yielded trivalent [(Me₄ TACD)AlH][BAr₄ ^Me ]₂ . Protonation of [(Me₄ TACD)Ga][BAr₄ ^Me ] with [Et₃ NH][BAr₄ ^Me ] gave an unusually acidic (pK_a (CH₃ CN)=24.5) gallium(III) hydride dication [(Me₄ TACD)GaH][BAr₄ ^Me ]₂ . Deprotonation with IMe₄ (1,3,4,5-tetramethyl-imidazol-ylidene) returned [(Me₄ TACD)Ga][BAr₄ ^Me ]. These reversible processes occur with formal two-electron oxidation and reduction of gallium. DFT calculations suggest that gallium(I) protonation is facilitated by strong coordination of the tetradentate ligand, which raises the HOMO energy. High nuclear charge of [(Me₄ TACD)GaH]²⁺ facilitates hydride-to-metal charge transfer during deprotonation. Attempts to prepare a gallium(III) dihydride cation resulted in spontaneous dehydrogenation to [(Me₄ TACD)Ga]⁺ .

SUBMITTER: Morris LJ

PROVIDER: S-EPMC9304309 | biostudies-literature | 2022 Mar

REPOSITORIES: biostudies-literature

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A Brønsted Acidic Gallium Hydride: Facile Interconversion of NNNN-Macrocycle Supported [GaI ]+ and [GaIII H]2.

Morris Louis J LJ Ghana Priyabrata P Rajeshkumar Thayalan T Carpentier Ambre A Maron Laurent L Okuda Jun J

Angewandte Chemie (International ed. in English) 20220127 11

Protonolysis of [Cp*M] (M=Ga, In, Tl) with [(Me4 TACD)H][BAr4 Me ] (Me4 TACD=N,N',N'',N'''-tetramethyl-1,4,7,10-tetraazacyclododecane; [BAr4 Me ]- =[B{C6 H3 -3,5-(CH3 )2 }4 ]- ) provided monovalent salts [(Me4 TACD)M][BAr4 Me ], whereas [Cp*Al]4 yielded trivalent [(Me4 TACD)AlH][BAr4 M ...[more]

PMID: 34932267

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Project description:BackgroundProstate-specific membrane antigen (PSMA) is expressed in the microvasculature of thyroid cancer. This suggests the potential use of PSMA as a diagnostic agent in patients with aggressive forms of thyroid cancer. The purpose of the current study was to determine the feasibility and utility of [68Ga]Ga-PSMA-11 PET/MRI in thyroid cancer patients.MethodsEligible patients for this prospective pilot study were adults with a history of pathology-proven thyroid cancer who had abnormal radiotracer uptake on an 2-[18F]FDG PET and/or 131I scintigraphy performed in the 12 months prior to study enrollment. Patients underwent a [68Ga]Ga-PSMA-11 PET/MRI, and comparison was made to the prior qualifying 2-[18F]FDG PET CT/MRI for lesion location and relative intensity.ResultsTwelve patients underwent [68Ga]Ga-PSMA-11 PET/MRI, one of which was excluded from analysis due to debulking surgery prior to the PSMA PET. Of the remaining patients, 7/11 had differentiated disease (3 papillary, 2 follicular, 2 Hurthle cell) and 4/11 had dedifferentiated disease (2 poorly differentiated papillary, 2 anaplastic). Out of 43 lesions, 41 were visually 2-[18F]FDG positive (uptake greater than background, detection rate 95.3%) and 28 were PSMA positive (uptake greater than background, detection rate 65.1%). Uptake was heterogeneous between patients, and in some cases within patients. 3/11 patients (1 poorly differentiated papillary, 2 follicular) had PSMA uptake which was greater than FDG uptake. For the remaining 8 patients, 2-[18F]FDG uptake was greater than PSMA. Using one eligibility guideline in the prostate cancer literature for PSMA radioligand therapy (RLT), 8/11 could be considered eligible for possible future PSMA RLT. This was not predictable based on thyroid cancer subtype.Conclusions[68Ga]Ga-PSMA-11 PET demonstrated lower detection rate when compared to 2-[18F]FDG PET for thyroid cancer lesion visualization. Thyroid cancer subtype alone may not be sufficient to predict PSMA uptake, and radiotracer uptake may vary between patients and even within patients.

Project description:Purpose[18F]Fluorodeoxyglucose (FDG) is widely used in PET/CT imaging to detect large vessel vasculitis in giant cell arteritis (GCA), but its performance is suboptimal in patients receiving glucocorticoids. We aimed to compare [68Ga]Ga-HA-DOTA-TATE, a somatostatin 2-analogue tracer, to [18F]FDG in a pilot study of patients with GCA.MethodsEight patients with active GCA were prospectively, sequentially scanned with both [18F]FDG PET/CT and [68Ga]Ga-HA-DOTA-TATE PET/CT imaging. Images were evaluated by 2 blinded nuclear medicine specialists. Tracer uptake was assessed in 8 vascular territories using SUVmax, and target-background ratios (TBR) were calculated using both right atrium (TBRRA) and liver mean (TBRliver). Mean SUVmax and TBR of individual vascular territories and index vessels were compared.ResultsThe patient median age was 71.5 years (range 64-82), and 4 (50%) were women. Active vasculitis (≥ grade 2 visual uptake in large vessels) was present in 62.5% of [18F]FDG scans. [18F]FDG scans had higher RA background activity than [68Ga]Ga-HA-DOTA-TATE (mean RA SUVmean 1.88 vs. 0.36, p < 0.001), while [68Ga]Ga-HA-DOTA-TATE had a significantly higher liver uptake (mean liver SUVmean 7.54 vs. 2.39, p < 0.001). Vascular uptake (as measured by both SUVmax and TBRliver) was significantly higher in [18F]FDG than [68Ga]Ga-HA-DOTA-TATE scans in every vascular territory (p < = 0.05 for all comparisons), including index vessels (SUVmax 4.04 vs. 1.91, p = 0.01, TBRliver 1.73 vs. 0.27, p < 0.001).ConclusionIn this pilot study of patients with active GCA, the arterial uptake of [68Ga]Ga-HA-DOTA-TATE was lower and less conspicuous compared to [18F]FDG. While further evaluation in larger cohorts is needed, a clear advantage of [68Ga]Ga-HA-DOTA-TATE over [18F]FDG for detecting vascular inflammation in GCA was not identified. TRIAL REGISTRATION, CLINICALTRIALS.GOV: NCT03812302, registered 2019-01-18, URL: https://clinicaltrials.gov/search?cond=dotatate%20%26;term=giant%20cell%20arteritis .

Dataset Information

A Bronsted Acidic Gallium Hydride: Facile Interconversion of NNNN-Macrocycle Supported [Ga^I ]⁺ and [Ga^III H]².

Publications

A Brønsted Acidic Gallium Hydride: Facile Interconversion of NNNN-Macrocycle Supported [Ga<sup>I</sup> ]<sup>+</sup> and [Ga<sup>III</sup> H]<sup>2</sup>.

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Dataset Information

A Bronsted Acidic Gallium Hydride: Facile Interconversion of NNNN-Macrocycle Supported [GaI ]+ and [GaIII H]2.

Publications

A Brønsted Acidic Gallium Hydride: Facile Interconversion of NNNN-Macrocycle Supported [Ga<sup>I</sup> ]<sup>+</sup> and [Ga<sup>III</sup> H]<sup>2</sup>.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

A Bronsted Acidic Gallium Hydride: Facile Interconversion of NNNN-Macrocycle Supported [Ga^I ]⁺ and [Ga^III H]².