Asymptotically Optimal Adversarial Strategies for the Probability Estimation Framework.

The probability estimation framework involves direct estimation of the probability of occurrences of outcomes conditioned on measurement settings and side information. It is a powerful tool for certifying randomness in quantum nonlocality experiments. In this paper, we present a self-contained proof of the asymptotic optimality of the method. Our approach refines earlier results to allow a better characterisation of optimal adversarial attacks on the protocol. We apply these results to the (2,2,2) Bell scenario, obtaining an analytic characterisation of the optimal adversarial attacks bound by no-signalling principles, while also demonstrating the asymptotic robustness of the PEF method to deviations from expected experimental behaviour. We also study extensions of the analysis to quantum-limited adversaries in the (2,2,2) Bell scenario and no-signalling adversaries in higher (n,m,k) Bell scenarios.

Hydrogen Production from Formaldehyde and Paraformaldehyde in Water under Additive-Free Conditions: Catalytic Reactions and Mechanistic Insights.

Efficient catalytic systems based on arene-Ru(II) complexes bearing bis-imidazole methane-based ligands were developed to achieve additive-free hydrogen generation from formaldehyde and paraformaldehyde in water. Our findings inferred the influential role of bis-imidazole methane ligands in the observed catalytic performance of the studied catalysts. Among the screened complexes, [(η6-p-cymene)RuCl(L)]+Cl- ([Ru]-2) (L = 4,4'-((2-methoxyphenyl)methylene)bis(2-ethyl-5-methyl-1H-imidazole) outperformed others to generate hydrogen gas from paraformaldehyde in water with an exceptionally high turnover number (TON) of >20,000. A detailed mechanistic pathway for hydrogen gas generation from formaldehyde has been proposed on the basis of identified several crucial catalytic intermediate species involved in the hydrogen production process.

Bis-Imidazole Methane Ligated Ruthenium(II) Complexes: Synthesis, Characterization, and Catalytic Activity for Hydrogen Production from Formic Acid in Water.

A series of half sandwich arene-ruthenium complexes [(η6-arene)RuCl(κ2-L)]+ ([Ru]-1-[Ru]-10) containing bis-imidazole methane-based ligands {4,4'-(phenylmethylene)bis(2-ethyl-5-methyl-1H-imidazole)} (L1), {4,4'-((4-methoxyphenyl)methylene)bis(2-ethyl-5-methyl-1H-imidazole)} (L2), {4,4'-((2-methoxyphenyl)methylene)bis(2-ethyl-5-methyl-1H-imidazole)} (L3), {4,4'-((4-chlorophenyl)methylene)bis(2-ethyl-5-methyl-1H-imidazole)} (L4), and {4,4'-((2-chlorophenyl)methylene)bis(2-ethyl-5-methyl-1H-imidazole)} (L5) are synthesized. The synthesized and purified complexes ([Ru]-1-[Ru]-10) are further employed for hydrogen production from formic acid in aqueous medium. Among the investigated complexes, [(η6-p-cymene)RuCl(κ2-L2)]+ [Ru]-2, having Ru(II) coordinated 4-methoxy phenyl substituted bis-imidazole methane ligand (L2), outperformed over others, displaying a higher catalytic turnover of 8830 and high efficiency (TOF = 1545 h-1) with appreciably high long-term stability for formic acid dehydrogenation in water.

Hydrogen Production from Formic Acid and Formaldehyde over Ruthenium Catalysts in Water.

Water-soluble ruthenium complexes [(η6-arene)Ru(κ2-L)]n+ (n = 0,1) ([Ru]-1-[Ru]-9) ligated with pyridine-based ligands are synthesized, and the molecular structure of the representative complex [Ru]-2 is confirmed by X-ray crystallography. The studied complexes are employed for the catalytic dehydrogenation of formic acid in water. Screening of these complexes inferred that [Ru]-1 [(η6-C10H14)Ru(κ2-NpyOH-L1)Cl]+ (L1 = pyridine-2-ylmethanol) outperformed others with an initial turnover frequency of 1548 h-1. Complex [Ru]-1 also exhibited high stability in water and can be recycled up to seven times with a total turnover number of 6050. In addition to formic acid dehydrogenation, [Ru]-1 also catalyzed the conversion of formaldehyde to hydrogen gas in water under base-free conditions. The effects of temperature, pH, formic acid, and catalyst concentration on the reaction kinetics are investigated in detail. Mass and NMR based mechanistic investigations inferred the presence of several important intermediate species, such as ruthenium-formate species [Ru]-1B and ruthenium-hydride species [Ru]-1C, involved in the catalytic dehydrogenation reaction. Moreover, the molecular structure of a diruthenium species [Ru]-1A' is also authenticated by single-crystal X-ray crystallography.

Synthesis, structure and catalytic activity of manganese(ii) complexes derived from bis(imidazole)methane-based ligands.

New mononuclear manganese(ii) complexes [Mn(κ2-L1)(OAc)2] ([Mn]-1), [Mn(κ2-L2)(OAc)2] ([Mn]-2) and [Mn(κ2-L3)(OAc)2] ([Mn]-3) with imidazole based ligands {4,4'-(phenylmethylene)bis(2-ethyl-5-methyl-1H-imidazole)} (L1), {(4,4'-((2-methoxy phenyl)methylene)bis(2-ethyl-5-methyl-1H-imidazole)} (L2) and {4,4'-((2-chlorophenyl) methylene)bis(2-ethyl-5-methyl-1H-imidazole)} (L3) are synthesized and fully characterized by a variety of techniques. Furthermore, the molecular structures of complexes [Mn]-1 and [Mn]-2 are established by single crystal X-ray structure analysis. The synthesized manganese(ii) complexes exhibited efficient catalytic oxidative coupling of primary amines in air under solvent-free conditions to the corresponding imines in moderate to good yields.

Ruthenium Complexes for Catalytic Dehydrogenation of Hydrazine and Transfer Hydrogenation Reactions.

Catalytic dehydrogenation of hydrazine was achieved over iminopyridine ligated ruthenium-arene complexes, where the release of H2 gas, as confirmed by GC-TCD, from hydrazine depends on reaction temperature, base, and solvents. NMR and MS studies indicated an in situ generation of a hydrazine-coordinated ruthenium species, a key intermediate of hydrazine dehydrogenation, via a coordination-assisted activation pathway.