Dalton Transactions

doi: 10.1039/D2DT90109Apmid: N/A

doi: 10.1039/D2DT90110Bpmid: N/A

doi: 10.1039/D2DT90111Kpmid: N/A

Ghosh, Ayyan; Dasgupta, Sreeja; Kundu, Animesh; Mandal, Sukanta

doi: 10.1039/d2dt01124gpmid: 35730327

Water oxidation is the bottleneck for producing hydrogen from the water-splitting reaction. Developing efficient water oxidation catalysts (WOCs) has recently been of paramount interest. Ruthenium-based WOCs have gained much attention due to their enriched redox property, robust nature, and superior catalytic performances compared to other transition metal-based molecular catalysts. The performance of a catalyst is highly dependent on the design of the ligand framework. In nature, the secondary coordination sphere around the active site of a metalloenzyme plays a vital role in catalysis. This principle has been employed in the recent development of efficient catalysts. With the aid of secondary interactions, some landmark Ru-based WOCs, producing remarkable turnover frequencies (TOFs) in the order of 104 s1, have been developed. In this account, we have discussed the underlying chemistry related to the effect of secondary interactions (such as hydrogen-bonding, stacking, electrostatic interaction, hydrophobichydrophilic environment, etc.) on the kinetics of the water oxidation reaction catalysed by molecular Ru-complexes. The use of secondary interactions (such as and CH) in anchoring the molecular catalyst onto the solid conducting surface has also been discussed. We aim to provide a brief overview of the positive impact of outer-sphere engineering on water oxidation reactivity, which may offer guidelines for developing the next generation of advanced catalysts.

Fujiwara, Yusuke; Takayama, Tomoaki; Nakazawa, Jun; Okamura, Masaya; Hikichi, Shiro

doi: 10.1039/d2dt01548jpmid: 35703587

A novel anionic tridentate borate ligand with a 6-methylpyridyl donor, TpyMe, has been synthesized. Comparison of the molecular structures and reactivities of nickel(ii)-bromido complexes with tris(azolyl)borate ligands composed of pyridyl, pyrazolyl, or oxazolinyl donors indicates the characteristic sterically demanding nature and strong electron donating ability of TpyMe.

Chen, Kai; Luo, Yaojing; Shen, Peng; Liu, Xiaoxu; Li, Xingchuan; Li, Xiaotian; Chu, Ke

doi: 10.1039/d2dt01542kpmid: 35708159

The electrochemical nitrate reduction reaction (NO3RR) not only holds great potential for the removal of NO3 contaminants from the environment, but also potentially provides a renewable-energy-driven NH3 synthesis method to replace the HaberBosch process. Herein, we report that Fe-doped SnS2 nanosheets enriched with S-vacancies can be used as an efficient NO3RR catalyst, showing a high NH3 yield of 7.2 mg h1 cm2 (at 0.8 V) and a faradaic efficiency of 85.6% (at 0.7 V). Density functional theory (DFT) calculations revealed that S-vacancies on FeSnS2 serve as the main active sites for the NO3RR and the Fe-doping can further regulate the electronic structure of S-vacancies to optimize the binding energies of NO3RR intermediates, resulting in reduced energy barriers and enhanced NO3RR activity.

Wang, Man; Li, Han-Shu; Ding, Xin; Jiang, Lizan; Wu, Pengyan; Zheng, Ruiting; Bao, Guoyue; Liu, Guoliang; Wang, Jian

doi: 10.1039/d2dt01046apmid: 35762382

In this study, an imine-linked luminescent porous organic network (PON) has been successfully synthesized by the Schiff-base condensation reaction between 1,2-diphenylethylenediamine and tris(4-formylphenyl)amine. It exhibits strong fluorescence in an aqueous dispersion and can be applied as a luminescent probe for Cr(vi) (CrO42 and Cr2O72) with high selectivity and sensitivity (LOD for Cr2O72 and CrO42 were below 0.35 M and 0.4 M, respectively) in a turn-off manner. The possible luminescence sensing mechanism and the adsorption capacity of Cr(vi) are also discussed in detail.

Uhlmann, Cedric; Feuerstein, Thomas J.; Seifert, Tim P.; Jung, Andr P.; Gamer, Michael T.; Kppe, Ralf; Lebedkin, Sergei; Kappes, Manfred M.; Roesky, Peter W.

doi: 10.1039/d2dt00458epmid: 35776128

The versatile metalloligand [{HCCC(NDipp)2}2Au2] (dipp = 2,6-diisopropylphenyl) was converted into early-late heterotetrametallic complexes [{ClCp2MCCC(NDipp)2}2Au2] (M = Ti, Zr). These compounds show photoluminescence with either remarkably different (Ti) or similar (Zr) features as compared to related solely coinage metal containing acetylide amidinate complexes.

Pushie, M. Jake; Summers, Kelly L.; Nienaber, Kurt H.; Pickering, Ingrid J.; George, Graham N.

doi: 10.1039/d2dt01475kpmid: 35766122

Copper(ii) coordination by bis(cyclohexanone)oxalyldihydrazone (also known as cuprizone), resulting in the formation of an intensely coloured blue complex, was first reported over 70 years ago. The cuprizone reaction has been employed in colourimetric tests for the presence of trace levels of copper. Cuprizone administration in C57BL/6 mice also leads to demyelination over time a consequence that appears to be due to copper dyshomeostasis and this has led to use of cuprizone as the leading method for toxicant-induced generation of an animal model of demyelination since its first use in the 1960s. Despite broad interest in cuprizone and its ability to bind copper there have been relatively few studies to structurally characterize the copper coordination properties of this ligand. In the absence of an aqueous medium, such as neat alcohol, copper and cuprizone exclusively form an amorphous green precipitate. Under aqueous conditions, where a large excess of cuprizone (relative to copper) is present, the blue complex that is synonymous with coppercuprizone coordination is predominantly formed. The blue and green coppercuprizone products demonstrate poor solubility and present challenges for conventional structure characterization methods, such as X-ray crystallography or nuclear magnetic resonance spectroscopy. By combining mass spectrometry, X-ray absorption spectroscopy, computational chemistry, and other techniques, a self-consistent picture of the copper coordination structures of the blue and green complexes is revealed confirming that the blue complex is in the Cu(iii) state, containing two hydrolyzed cuprizone ligands per metal centre, while the green complex represents an extended oligomeric complex, comprised of repeating Cu(ii) centres that lie 4.8 apart and are bridged by unhydrolyzed cuprizone donors.

Pushie, M. Jake; George, Graham N.

doi: 10.1039/d2dt01476apmid: 35766818

The reaction of copper with bis(cyclohexanone)oxaldihydrazone (cuprizone) is a challenging coordination chemistry problem that has confounded attempts at elucidation for the past 70 years. The product of the reaction, a blue copper complex, wherein the cuprizone ligand is hydrolyzed, has been the primary focus during its history. We have recently characterized an additional green multi-copper product which contains unhydrolyzed cuprizone, which only added to the mystery. Using density functional structure models and thermodynamic calculations we address several of the long-standing questions surrounding the coppercuprizone reaction, as well as identify the likely reaction pathway that gives rise to the blue and green products. Cu(ii)-induced asymmetric hydrolysis of the cuprizone ligand is essential for formation of the blue product, followed by a series of Cu(ii)-induced deprotonation and coordination events, with complex formation terminating with hydrolyzed cuprizone tautomerization and intramolecular electron transfer, generating a pseudo-macrocyclic Cu(iii) species. Alternatively, in the presence of excess Cu(ii), or in non-aqueous solvents, a green multi-Cu(ii) complex forms comprised of alternating Cu(ii)cuprizone units. Structure calculations are supported by experimental data and represent the most rigorous approach to-date toward understanding the complex solution chemistry of copper with cuprizone.