Investigating pyridazine and phthalazine exchange in a series of iridium complexes in order to define their role in the catalytic transfer of magnetisation from para-hydrogen† †Electronic supplementary information (ESI) available: Synthesis, Characterisation, kinetic and hyperpolarisation data with the kinetic model is available here. See DOI: 10.1039/c5sc00756a
نویسندگان
چکیده
The reaction of [Ir(IMes)(COD)Cl], [IMes 1⁄4 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene, COD 1⁄4 1,5cyclooctadiene] with pyridazine (pdz) and phthalazine (phth) results in the formation of [Ir(COD)(IMes)(pdz)]Cl and [Ir(COD)(IMes)(phth)]Cl. These two complexes are shown by nuclear magnetic resonance (NMR) studies to undergo a haptotropic shift which interchanges pairs of protons within the bound ligands. When these complexes are exposed to hydrogen, they react to form [Ir(H)2(COD)(IMes)(pdz)]Cl and [Ir(H)2(COD)(IMes)(phth)]Cl, respectively, which ultimately convert to [Ir(H)2(IMes)(pdz)3]Cl and [Ir(H)2(IMes)(phth)3]Cl, as the COD is hydrogenated to form cyclooctane. These two dihydride complexes are shown, by NMR, to undergo both full N-heterocycle dissociation and a haptotropic shift, the rates of which are affected by both steric interactions and free ligand pKa values. The use of these complexes as catalysts in the transfer of polarisation from para-hydrogen to pyridazine and phthalazine via signal amplification by reversible exchange (SABRE) is explored. The possible future use of drugs which contain pyridazine and phthalazine motifs as in vivo or clinical magnetic resonance imaging probes is demonstrated; a range of NMR and phantom-based MRI measurements are reported.
منابع مشابه
Solvent responsive catalyst improves NMR sensitivity via efficient magnetisation transfer† †Electronic supplementary information (ESI) available: Experimental details; synthesis and characterisation of compounds, SABRE experiments, kinetic data, activation parameters, UV-vis data. The underlying research data for this paper is available in accordance with EPSRC open data policy from DOI: 10.15124/cdaf969f-ba47-401e-876b-512c0cece55c. See DOI: 10.1039/c6cc03185d Click here for additional data file.
A bidentate iridium carbene complex, Ir(κC,O-L1)(COD), has been synthesised which contains a strongly electron donating carbene ligand that is functionalised by a cis-spanning phenolate group. This complex acts as a precursor to effective magnetisation transfer catalysts which form after reaction with H2 and a suitable two electron donor. In solvents such as benzene, containing pyridine, they a...
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Shanghai Key Laboratory of Green Chem Chemistry and Molecular Engineering, Eas Zhongshan Road, Shanghai, 200062, P. R. C Laboratoire de Chimie, École Normale Su d’Italie, F-69364 Lyon, France Aix Marseille Univ, CNRS, Centrale Mar [email protected] † Electronic supplementary informatio instrumentations, synthesis and characte kinetic data, H NMR titrations, etc. See D Cit...
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Using signal amplification by reversible exchange (SABRE) to hyperpolarise 119Sn and 29Si NMR nuclei† †Data created during this research are available by request from the University of York Data Catalogue http://dx.doi.org/10.15124/12345. ‡ ‡Electronic supplementary information (ESI) available: General procedures and experimental conditions, sample preparation, performing SABRE experiments, ligand exchange rates, field dependent polarisation transfer studies, synthetic methods. CCDC 1501636 and 1501637. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c6cc07109k Click here for additional data file. Click here for additional data file.
The hyperpolarisation of the 119Sn and 29Si nuclei in 5-(tributylstannyl)pyrimidine (ASn) and 5-(trimethylsilyl)pyrimidine (BSi) is achieved through their reaction with [IrCl(COD)(IMes)] (1a) or [IrCl(COD)(SIMes)] (1b) and parahydrogen via the SABRE process. 1a exhibits superior activity in both cases. The two inequivalent pyrimidine proton environments of ASn readily yielded signal enhancement...
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