Transition from Low to High Iodide and Iodine Concentration States in the Briggs–Rauscher Reaction: Evidence on Crazy Clock Behavior

Pagnacco, Maja C.; Maksimović, Jelena P.; Potkonjak, Nebojša I.; Božić, Bojan; Horváth, Attila

doi:10.1021/acs.jpca.7b11774

Cited by 9 publications

(25 citation statements)

References 39 publications

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“…This expectation, along with the fact that the arsenous acid-iodate reaction exhibits crazy-clock behavior (CCB) as reported recently by our research group, 11 has led us to elucidate the comprehensive kinetic model of the arsenous acid-iodate system, 12,13 including the well-known Dushman 14 and Roebuck 15 reactions. Very recently, Pagnacco et al reported 16 that the state I (low iodide and iodine concentration) to state II (high iodide and iodine concentration) transition of the Briggs-Rauscher reaction 17 after leaving the strongly reproducible oscillatory state was found to be irreproducible as well. Moreover, an efficient mixing does not only prolong the time lag necessary for the state I to state II transition, it simply does not allow it to happen.…”

Section: Introductionmentioning

confidence: 99%

Imperfect mixing as a dominant factor leading to stochastic behavior: a new system exhibiting crazy clock behavior

Valkai

Horváth

2018

Phys. Chem. Chem. Phys.

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It is clearly demonstrated that the arsenous acid-periodate reaction displays crazy-clock behavior when a statistically meaningful number of kinetic runs are performed under "exactly the same" conditions. Both extensive experimental and numerical simulation results gave convincing evidence that the stochastic feature of the title reaction originates from the imperfection of the mixing process, and neither local random fluctuation nor initial inhomogeneity alone is capable of explaining adequately the observed phenomena. Imperfect mixing is manifested-in practice-in the unintentional and inherent formation of dead volumes where the concentration of the reactants may even significantly differ from the ones measured in the case of a completely uniform concentration distribution, and the system may spend enough time there under imperfectly mixed conditions to complete the nonlinear chemical process. Furthermore, it is also shown that a more efficient mixing, i.e. a smaller dead volume size and shorter residence time being spent in the dead volume, does not necessarily mean Landolt times are smaller than the one measured under completely homogeneous conditions. Evidently, the "initial" concentration of the reagents in the dead volume-and of course in the rest of the solution-greatly influences the Landolt time to be measured in the case of an individual kinetic run and may therefore show either positive or negative deviation from the Landolt time for the completely homogeneous state. As a result, less efficient mixing may either accelerate or decelerate the rate of a nonlinear autocatalytic reaction at a macroscopic volume level.

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Section: Introductionmentioning

confidence: 99%

Imperfect mixing as a dominant factor leading to stochastic behavior: a new system exhibiting crazy clock behavior

Valkai

Horváth

2018

Phys. Chem. Chem. Phys.

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Section: Introductionmentioning

confidence: 70%

“…Indeed, as described elsewhere [16], after the well-controlled initial oscillatory behavior, the reaction becomes chaotic. Depending on the initial conditions, particularly on the ratio [H 2 MA] 0 /[IO 3 − ] 0 [16,17], the reaction exhibits a sudden and unpredictable phase transition. This transition, from state I (low concentration of iodide and iodine) to state II (high concentration of iodide and iodine), happens randomly in practice, as the time spent by the system in the state I is irreproducible (see Figure 1).…”

Section: Introductionmentioning

confidence: 70%

“…It compares and processes statistically more than #60 experiments obtained under identical initial concentrations of all reactants. Although the BR crazy-clock phenomenon was previously detected [16], this behavior is linked for the first time to symmetry-breaking, highlighting the entire process in a novel way. Furthermore, the investigated crazy clock exhibits a truly random behavior that might be considered as an example of a classical, liquid random number generator.…”

Section: Introductionmentioning

confidence: 73%

“…Possible kinetical consequences are the appearance of bifurcation, chaos, intermittent behavior, and symmetry-breaking [18,19]. In the experiments of our previous paper [16], the mixing was stopped after an intensive homogenization (stirring at 900 rpm) of the Briggs-Rauscher solution in the oscillatory period. Herein, the experiments carried out with or without specific mixing were maintained all the time.…”

Section: Introductionmentioning

confidence: 99%

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Spontaneous Symmetry Breaking: The Case of Crazy Clock and Beyond

et al. 2022

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In this work, we describe the crazy-clock phenomenon involving the state I (low iodide and iodine concentration) to state II (high iodide and iodine concentration with new iodine phase) transition after a Briggs–Rauscher (BR) oscillatory process. While the BR crazy-clock phenomenon is known, this is the first time that crazy-clock behavior is linked and explained with the symmetry-breaking phenomenon, highlighting the entire process in a novel way. The presented phenomenon has been thoroughly investigated by running more than 60 experiments, and evaluated by using statistical cluster K-means analysis. The mixing rate, as well as the magnetic bar shape and dimensions, have a strong influence on the transition appearance. Although the transition for both mixing and no-mixing conditions are taking place completely randomly, by using statistical cluster analysis we obtain different numbers of clusters (showing the time-domains where the transition is more likely to occur). In the case of stirring, clusters are more compact and separated, revealed new hidden details regarding the chemical dynamics of nonlinear processes. The significance of the presented results is beyond oscillatory reaction kinetics since the described example belongs to the small class of chemical systems that shows intrinsic randomness in their response and it might be considered as a real example of a classical liquid random number generator.

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Stabilization of the Alkylammonium Cations in Halide Perovskite Thin Films by Water‐Mediated Proton Transfer

et al. 2023

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has attracted much research attention, more fundamental studies are required to achieve viable and stable ALHPs.The deprotonation of alkylammonium can cause the instability of ALHP crystal growth according to several studies of proton defects in the alkylammonium of ALHP. Zhang et al. reported that the thermodynamic instability of ALHP arises due to hydrogen vacancies in the crystal, as found by density functional theory calculations. [4] Cardenas-Daw et al. [5] have reported crystal phase destabilization by the undesired formation of methylamine (MA) from methylammonium (MA + ) in MAPbI 3 crystals. Doherty et al. [6] solved the destabilization issue by adding ethylenediaminetetraacetic acid into the perovskite precursor, which protonated the alkylammonium (A-site) molecule, resulting in stabilizing ALHP crystal growth. However, the specific mechanisms and relations between the protonation of the alkylammonium molecule and the stabilization of the ALHP crystal structure were not discussed.Meanwhile, halide-induced protonation can be considered to obtain the stable perovskite phase, according to a report from Bajaj et al. [7] They highlighted the important role of I −mediated hydrogen (H) bonding rearrangement of H 2 O in the iodide-dihydrate complex. In a similar principle, halideinduced protonation can occur with the H 2 O in the perovskite The development of alkylammonium lead trihalide perovskite (ALHP) photovoltaics has grown rapidly over the past decade. However, there are remaining critical challenges, such as proton defects, which can lead to the material instability of ALHPs. Although specific strategies, including the use of halide additives, have significantly reduced the defects, a fundamental understanding of the defect passivation mechanism remains elusive. Herein, an approach and mechanism for minimizing proton defects in ALHP crystals by adding ionized halides to the perovskite precursor solution are reported. This work clarifies that the ionized halides induced proton transfer from H 2 O to the alkylammonium cation in the precursor solution, stabilizing the ALHP crystals. The fundamental characteristics of ALHP and its precursors are examined by X-ray diffraction, transmittance electron microscopy, in situ extended X-ray absorption fine structure, Fourier transform NMR spectroscopy, and Fourier transform infrared spectroscopy. The findings from this work will guide the development of highly stable ALHP crystals, enabling efficient and stable optoelectronic ALHP devices.

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Transition from Low to High Iodide and Iodine Concentration States in the Briggs–Rauscher Reaction: Evidence on Crazy Clock Behavior

Cited by 9 publications

References 39 publications

Imperfect mixing as a dominant factor leading to stochastic behavior: a new system exhibiting crazy clock behavior

Imperfect mixing as a dominant factor leading to stochastic behavior: a new system exhibiting crazy clock behavior

Spontaneous Symmetry Breaking: The Case of Crazy Clock and Beyond

Stabilization of the Alkylammonium Cations in Halide Perovskite Thin Films by Water‐Mediated Proton Transfer

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