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Abstract Macrocyclic Co(II) complexes with appended amide‐glycinate groups were prepared to develop paramagnetic Co(II) chemical exchange saturation transfer (CEST) agents of reduced overall charge. Complexes with reduced charge and lowered osmolarity are important for their loading into liposomes and to provide complexes that are highly water soluble and well tolerated in animals. Co(L1) has two non‐coordinating benzyl groups and two amide‐glycinate pendants, whereas Co(L2) has two unsubstituted amide pendants and two amide‐glycinate pendants on cyclam (1,4,8,11‐tetraazacyclododecane). The¹H NMR spectrum of Co(L1) is consistent with a singlecis‐pendant isomer with both amide protons in thetrans‐configuration, as supported by an X‐ray crystal structure. Co(L2) has a mixture of different isomers in solution, including thetrans‐1,4 and 1,8 pendant isomers. The Z‐spectrum of Co(L1) shows one highly‐shifted CEST peak, whereas Co(L2) exhibits six CEST peaks. Encapsulation of 40 mM Co(L1) in a liposome with osmotically‐induced shrinking at 300 mOsm/L produces a liposomal CEST agent with saturation frequency offset of 3 ppm. Addition of the amphiphilic 1,4,7‐triazacyclononane‐based complex Co(L5) to the liposomal bilayer at 18 mM with Co(L1) encapsulated in the liposome at 50 mM changes the sign and increases the magnitude of the saturation frequency offset to −7.5 ppm at 300 mOsm/L. 

We determine the factors that influence nucleation and growth of VOOH with star morphology and evaluate its performance in Na-ion batteries, revealing how precursor chemistry and reaction kinetics shape structural evolution in this system. 

Herein, we report the coordination-driven self-assembly of a diazaporphyrin plate and a porphyrin prism, made using the same Ru-benzo molecular clip and 2:1 diruthenium acceptor to tetrapyridyl donor stoichiometry, and discuss characterization techniques used to distinguish the two. We describe how 1H NMR data can distinguish between plate and prism geometries based on peak shifts and splitting in the context of molecular symmetries. DOSY spectra show changes in hydrodynamic radius from the monomeric porphyrin to the prism (4.78 Å to 15.2 Å) and diazaporphyrin to plate (6.02 Å to 12.2 Å) consistent with the increase in size upon assembly. High resolution mass spectrometry provides further evidence for plate and prism, where specific peaks at diagnostic m/z values unequivocally establish the stoichiometry of assembly. Electronic absorption spectroscopy revealed a marked increase in molar absorptivity upon self-assembly. These results establish how molecular characterization techniques may be used to distinguish between possible self-assembly outcomes when a given building block may be encoded with directionality that is suitable for more than one geometry. 

Actinide doping enhances redox chemistry of polyoxomolybdate-alkoxide clusters; the first isolable U(v) polyoxometalate cluster is reported. 

Fe(iii) macrocyclic complexes with mixed oxygen donor pendants are studied as T₁MRI probes. Complexes with a phenolate pendant are among the most promising and produce pH dependent relaxivity profiles consistent with proton exchange pathways.