Deciphering the origin of million-fold reactivity observed for the open core diiron [HO-Fe-O-Fe[double bond, length as m-dash]O] species towards C-H bond activation: role of spin-states, spin-coupling, and spin-cooperation.

High-valent metal-oxo species have been characterised as key intermediates in both heme and non-heme enzymes that are found to perform efficient aliphatic hydroxylation, epoxidation, halogenation, and dehydrogenation reactions. Several biomimetic model complexes have been synthesised over the years to mimic both the structure and function of metalloenzymes. The diamond-core [Fe(μ-O)] is one of the celebrated models in this context as this has been proposed as the catalytically active species in soluble methane monooxygenase enzymes (sMMO), which perform the challenging chemical conversion of methane to methanol at ease.

Are cucurbiturils better drug carriers for bent metallocenes? Insights from theory.

Bent metallocenes (BM) have anti-tumor properties but they face a serious drug efficacy problem due to poor aqueous solubility and rapid hydrolysis under physiological conditions. These two problems can be fixed by encapsulating them in host molecules such as cyclodextrin (CD), cucurbituril (CB) etc. Experimentally, CD-BM, CB-BM host-guest complexes have been investigated to check the efficiency of the drug delivery and efficiency of the encapsulated drug.

Redox Self-Adaptation of a Nitrene Transfer Catalyst to the Substrate Needs.

The development of iron catalysts for carbon-heteroatom bond formation, which has attracted strong interest in the context of green chemistry and nitrene transfer, has emerged as the most promising way to versatile amine synthetic processes. A diiron system was previously developed that proved efficient in catalytic sulfimidations and aziridinations thanks to an Fe Fe active species. To deal with more demanding benzylic and aliphatic substrates, the catalyst was found to activate itself to a Fe Fe L active species able to catalyze aliphatic amination.

Sequence selectivity of azinomycin B in DNA alkylation and cross-linking: a QM/MM study.

Azinomycin B--a well-known antitumor drug--forms cross-links with DNA through alkylation of purine bases and blocks tumor cell growth. This reaction has been modeled using the ONIOM (B3LYP/6-31+g(d):UFF) method to understand the mechanism and sequence selectivity. ONIOM results have been checked for reliability by comparing them with full quantum mechanics calculations for selected paths.

Antitumor activity of bent metallocenes: electronic structure analysis using DFT computations.

The antitumor activities of bent metallocenes [Cp-M-Cp](2+) (M = Ti, V, Nb, Mo) and complexes of them with guanine, adenine, thymine and cytosine nucleotides have been probed using electronic structure calculations. DFT/BP86 calculations have revealed that the bent metallocene-nucleotide interaction strongly depends on the stability of the hydrolyzed form of the bent metallocene dichloride [Cp(2)M](2+) species, and in turn the stability of the [Cp(2)M](2+) species strongly depends on the electronic structure of [Cp(2)M](2+). Detailed electronic structure and Walsh energy analyses have been carried out for the hydrolyzed forms of four [Cp-M-Cp](2+) (M = Ti, V, Nb, Mo) species to find out why the bent structure is unusually stable.