Reduction of O2 to H2O2 using Small Polycyclic Molecules

Hydrogen peroxide is an environmentally friendly oxidizing agent that is important in several industries. It is currently produced industrially via the anthrahydroquinone (AHQ) process where O2 reacts with a functionalised version of anthrahydroquinone to produce H2O2 and anthraquinone. In the previously published DFT pathway for this process the transition of the OOH? radical across the partially dehydrogenated AHQ catalyst was not explored. In this paper, we will use DFT to explore this step and show that there is a deep potential energy minimum that inhibits the OOH^. from being fully reduced. We then examine other similar sized polycyclic molecules with two OH-groups on the same side that could serve as alternative catalysts without this issue. In this analysis, we identify Phenanthraquinone as a possible alternative and present the pathway for this candidate to produce H2O2 as well as its regeneration with H2.

Reduction of O2 to H2O2 using Small Polycyclic Molecules

Hydrogen peroxide is an environmentally friendly oxidizing agent that is important in several industries. It is currently produced industrially via the anthrahydroquinone (AHQ) process where O2 reacts with a functionalised version of anthrahydroquinone to produce H2O2 and anthraquinone. In the previously published DFT pathway for this process the transition of the OOH? radical across the partially dehydrogenated AHQ catalyst was not explored. In this paper, we will use DFT to explore this step and show that there is a deep potential energy minimum that inhibits the OOH^. from being fully reduced. We then examine other similar sized polycyclic molecules with two OH-groups on the same side that could serve as alternative catalysts without this issue. In this analysis, we identify Phenanthraquinone as a possible alternative and present the pathway for this candidate to produce H2O2 as well as its regeneration with H2.

Reduction of O2 to H2O2 using Small Polycyclic Molecules

Hydrogen peroxide is an environmentally friendly oxidizing agent that is important in several industries. It is currently produced industrially via the anthrahydroquinone (AHQ) process where O2 reacts with a functionalised version of anthrahydroquinone to produce H2O2 and anthraquinone. In the previously published DFT pathway for this process the transition of the OOH? radical across the partially dehydrogenated AHQ catalyst was not explored. In this paper, we will use DFT to explore this step and show that there is a deep potential energy minimum that inhibits the OOH^. from being fully reduced. We then examine other similar sized polycyclic molecules with two OH-groups on the same side that could serve as alternative catalysts without this issue. In this analysis, we identify Phenanthraquinone as a possible alternative and present the pathway for this candidate to produce H2O2 as well as its regeneration with H2.

Towards the Search for Thallium Nuclear Schiff Moment in Polyatomic Molecules: Molecular Properties of Thallium Monocyanide (TlCN)

Molecular properties of the thallium monocyanide (Tl·CN) system in its ground electronic state are studied using high-precision ab initio relativistic two-component pseudopotential replacing 60 inner-core electrons of Tl. A relativistic coupled-cluster method with single, double and perturbative triple amplitudes is employed to account for electronic correlations. Extrapolation of results to the complete basis set limit is used for all studied properties. The global potential energy minimum of Tl·CN corresponds to the linear cyanide (TlCN) isomer, while the non-rigid isocyanide-like (TlNC) structure lies by approximately 11 kJ/mol higher in energy. The procedure of restoration of the wavefunction in the “core” region of Tl atom was applied to calculate the interaction of the Tl nuclear Schiff moment with electrons. The parameter X of the interaction of the Tl nuclear Schiff moment with electrons in the linear TlCN molecule equals 7150 a.u. The prospects of using the TlCN molecule for the experimental detection of the nuclear Schiff moment are discussed.

PROTEIN FOLDING AS A RESULT OF 'SELF-REGULATED STOCHASTIC RESONANCE': A NEW PARADIGM?

We scrutinize the available (seemingly disparate) theories of protein folding and propose a new concept which brings them under one roof. First, we single out dipole–dipole coupling within protein backbone as the main reason for intrinsic double-well nature of the protein potential. Then, protein folding as a whole ought to be (at least) a two-stage process, namely: (a) both amino-acid side chains and solvent enslave the dynamics of the backbone to reach the folding transition state with the help of stochastic resonance, and (b) the backbone funnels the whole protein into the global potential energy minimum by enslaving the dynamics of the amino-acid side chains plus solvent, and simultaneously arresting the stochastic resonance prerequisites to lock the protein in its folded state. The latter is accomplished owing to the concerted action of the protein compactization (enthalpic contribution) and thermal motion intensification (entropic contribution), which is, in fact, a physical hallmark of enthalpy–entropy compensation.

Ab initio and DFT conformational analysis of selected flavones: 5,7-dihydroxyflavone (chrysin) and 7,8-dihydroxyflavone

Ab initio and DFT conformational analysis was performed on the flavone derivatives chrysin (5,7-dihydroxyflavone; 2-phenyl-5,7-dihydroxy-4H-1-benzopyran-4-one) and 7,8-dihydroxyflavone (2-phenyl-7,8-dihydroxy-4H-1-benzopyran-4-one). The structural features required for optimal stabilization in each molecule were identified. It was discovered that sparsely placed hydroxyl groups, particularly with hydrogen bond-like interactions, resulted in lowering the potential energy minimum for the molecules. It was also noted that one of the factors capable of destroying co-planarity was steric interference between closely placed functional groups across the phenyl and the benzo-γ-pyrane ring. Studies performed on the radical forms of the flavonoids, however, showed that the unpaired electron is confined only to the benzo-γ-pyrane ring, and not delocalized across the phenyl ring.Key words: flavonoid, flavone, chrysin, ab initio conformational analysis, anti-oxidant, free radical, 5,7-dihydroxy flavone, 7,8-dihydroxyflavone.