Self-Organization Induced by Self-Assembly in Microheterogeneous Reaction-Diffusion System

Two-dimensional infrared spectral explorations into bilayer and monolayer self-assemblies of amphiphilic polypeptides

Poly(2-(3-((2-hydroxyethyl)amino)-3-oxopropyl)ethyleneamido) (PHAOE) is an amphiphilic polypeptide. The self-assembly is significant, but the ultrafast dynamic analyses of the peptide self-assembly are exiguous and worth further exploring. In this investigation, the temporal dynamic characteristics of the aggregates and unaggregated PHAOEs are mined by the two-dimensional infrared (2D IR) spectroscopy. The homogeneous and inhomogeneous diffusion processes of the carbonyl stretching modes of the unaggregated PHAOEs are slower than those of the self-assemblies. The inhomogeneous spectral diffusion proportion of the biopolymer PHAOE in methanol is greater than that in dimethyl sulfoxide (DMSO). The solvation shells surround the aggregates and unaggregated PHAOEs in the protic solvent methanol, but there are not any solvation shells around the aggregates or unaggregated PHAOEs in the dipolar solvent DMSO. The massive hydrogen-bonded monolayer self-assembly has merely an aggregate of PHAOEs and no solvation shell in DMSO. But the hydrogen-bonded bilayer self-assembly has a self-assembled methanol shell and an interior aggregate of PHAOEs in methanol. The self-assemblies of PHAOEs motivate the methanols to self-assemble. The large delocalized amide structure results in the fast spectral diffusion of the carbonyl stretching mode.Communicated by Ramaswamy H. Sarma.

0D–2D heterostructures as nanocatalysts for self-oscillating reactions: an investigation into chemical kinetics

Ceria-decorated graphene nanocomposites as an efficient catalyst for the oscillatory Belousov–Zhabotinsky reaction.

Measurements and Simulations of the Acidity Dependence of the Kinetics of the Iron-Catalyzed Belousov-Zhabotinsky Reaction: Proton-Catalysis in the Electron Transfer Reaction Involving the [Fe(phen)3]3+ Species

The acidity dependence of the iron-catalyzed bromate-malonic acid Belousov-Zhabotinsky reaction was studied in the range 0.36 M < [H₂SO₄]₀ < 1.20 M, and the temporal evolutions of the oscillation patterns were analyzed. The experimental results show that the period times PT _i decrease exponentially with increasing acidity and that the period times parallel the decrease of the reduction times RT with increasing acidity. Simulations using the reactions of the commonly accepted core reaction mechanism failed to match the measurements even in a qualitative fashion. However, we found that compelling agreement between the experiments and the simulations can be achieved over the entire range with the inclusion of second-order proton-catalysis of the oxidation of bromomalonic acid (BrMA) by the [Fe(phen)₃]³⁺ species in the reaction identified in this paper as reaction 9 (R9), and this [H⁺] dependence is informative about the species involved in the outer sphere electron transfer reaction. The trication [Fe(phen)₃]³⁺ species is stabilized by ion pairing and solvation, and one may anticipate the presence of [Fe(phen)₃(HSO₄) _n(H₂O) _m]^{(3- n)+} species ( n = 0-3). Our results suggest that the removal of aggregating HSO₄^- ions by protonation creates a better oxidant and facilitates the approach of the reductant BrMA, and the second-order [H⁺] dependence further suggests that BrMA is primarily oxidized by a doubly charged [Fe(phen)₃(HSO₄)₁(L) _k]²⁺ species. Considering the complexity of the BZ system and the uncertainties in the many reaction rate constants, we were somewhat surprised to find this high level of agreement by (just) the replacement of R9 by R9'. In fact, the near-quantitative agreement presents a powerful corroboration of the core reaction mechanism of the BrMA-rich BZ reaction, and the replacement of R9 by R9' extends the validity of this core reaction mechanism to acidities above and below the typical acidity of BZ reactions ([H⁺] ≈ 1 M).