Zhabotinsky Reaction Research Articles

Designing polymer gels and composites that undergo bio-inspired phototactic reconfiguration and motion

Inspired by the adaptive behavior of photo-responsive biological organisms, we develop analytical and computational models to design polymer gels and composites that can be dynamically reconfigured and driven to move with the application of light. We focus on gels formed from poly(N-isopropylacrylamide) and functionalized with spirobenzopyran (SP) chromophores, which become hydrophobic under blue light in acidic aqueous solution. Using our modeling approaches, we irradiate the gels through photomasks and demonstrate that the shapes of the samples can be reversibly and remotely ‘remolded’ by varying the apertures in the masks. By simulating the effect of repeatedly moving the light across the sample, we also show that the gel can undergo directed motion. We then examine gels that contain both SP chromophores and the ruthenium catalysts that drive the oscillatory Belousov–Zhabotinsky reaction. These dual-functionalized gels undergo spontaneous, self-sustained motion even when the lights are held stationary. We also simulate the behavior of composites formed from SP-functionalized fibers embedded in the poly(N-isopropylacrylamide) gel. With the SP-functionalization confined to the fibers, light and heat act as orthogonal stimuli and thus the composites display distinctly different modes of movement when the different cues are applied to the samples. Overall, our findings provide guidelines for using light to controllably reconfigure the shape and drive the movement of gel-based materials and thus, tailor the material to display different functionalities.

Autonomous oscillating microgels involving Fe(phen)3 catalyst synchronized with the Belousov–Zhabotinsky reaction

ABSTRACTA novel kind of microgels’ poly(NIPAAm-co-Fe(phen)3-co-CS) were prepared by copolymerization of N-isopropylacrylamide (NIPAAm), chitosan (CS), and iron(II) 5-acrylamide-1,10-phenanthroline-bis(1,10-phenanthroline) (denoted as Fe(phen)3), the catalyst for the Belousov–Zhabotinsky (BZ) reaction. The microgels were characterized by FTIR spectroscopy, scanning electron microscope, and static water contact angle. In addition, the self-oscillating behaviors of the microgels were investigated in BZ system free of catalyst. Both the redox potential and transmittance self-oscillation were observed. Moreover, the self-oscillating parameters, such as the induction period, oscillating period, duration, and amplitude decreased with the increasing of CS contents. This special property enables them to be used as biocompatible materials for a variety of applications.

Aspects of the Belousov-Zhabotinsky Reaction inside a Self-Oscillating Polymer Brush.

We have developed a novel polymer brush surface exhibiting autonomous swelling-deswelling changes driven by the Belousov-Zhabotinsky (BZ) reaction, that is, the self-oscillating polymer brush. In this system, the ruthenium tris(2,2'-bipyridine) [Ru(bpy)3] catalyst-conjugated polymer chains are densely packed on the solid substrate. It is expected that the BZ reaction in the polymer brush would be influenced by the immobilization effect of the catalyst. To clarify the effect of the immobilization of the catalyst on the self-oscillating polymer brush, the self-oscillating behavior of the polymer brush was investigated by comparing it with that of other self-oscillating polymer materials, the free polymer, and the gel particle under various initial substrate concentrations. The initial substrate dependency of the oscillating period for the polymer brush was found to be different from those for the free polymer and the gel particle. Furthermore, the oscillatory waveform was analyzed on the basis of the Field-Körös-Noyes model. These investigations revealed that the dense immobilization of the self-oscillating polymer on the surface restricted accessibility for the Ru(bpy)3 moiety. These findings would be helpful in understanding the reaction-diffusion mechanism in the polymer brush, which is a novel reaction medium for the BZ reaction.

Feed rate noise modulates autocatalysis and shapes the oscillations of the Belousov–Zhabotinsky reaction in a continuous stirred tank reactor

Noise applied to a specific reactant feed rate directs the Belousov–Zhabotinsky reaction into specific pathways and results in noise-controlled oscillation shapes and features.

Mesoscopic Reaction–Diffusion Fronts Control Biomorph Growth

Biomorphs are inorganic assemblies of crystalline nanorods that form noncrystalline microshapes such as helices, funnels, and leaf-shaped sheets. This nanoscale-to-microscale self-organization occurs from simple reactants in aqueous solution and suggests new engineering methods as well as insights into biomineralization; to date, however, the underlying mechanisms are not understood. Here we describe a reaction–diffusion model for sheet growth that reproduces the experimentally observed biomorph shapes. The sheet edges are logarithmic spirals caused by the propagation failure of the crystallization front. The resulting defect motion is dynamically related to nonlinear wave dynamics in subexcitable media such as the photoinhibited Belousov–Zhabotinsky reaction. An expanded model includes a nematic-like director field that sets the average nanorod orientation irreversibly during crystallization. The growth front of worm-like biomorph helices also obeys logarithmic spirals, suggesting future applications of ...

Analysis of self-oscillating behaviors aimed at the development of a molecular robot with organic acids as fuel

We studied the transmittance self-oscillation of a polymer chain driven by an organic acid as the fuel. The self-oscillating polymer chain consists of 4-acryloylmorpholine (ACMO) and the Ru catalyst (Ru(bpy)3) of the Belousov–Zhabotinsky (BZ) reaction. The transmittance self-oscillating behavior was affected significantly by the temperature. As the amplitude of the transmittance self-oscillation, which is reflected by the aggregation state, decreased with time, the oscillation period also decreased. This trend indicates that the polymer aggregation affects the rate of the BZ reaction significantly. The activation energy of the self-oscillating value was almost the same in the normal BZ reaction, which does not include Ru(bpy)3 complexes in the polymer chains. In addition, we demonstrated the effect of one BZ substrate (sodium bromate or malonic acid) on the transmittance self-oscillation period.

A Delay-Based Sustained Chemical Oscillator: Qualitative Analysis of Oregonator-Based Models

The Belousov–Zhabotinsky (BZ) reaction is a complex chemical reaction exhibiting sustained oscillations observed in some real biological oscillators. However, its oscillatory behavior is represented by a simple mechanism, called the Oregonator . Since delay induces unexpected behaviors, the dynamics in BZ reaction in the presence of delays has not been sufficiently addressed. In order to understand the effects induced by the delay parameter in the reaction, by using a two-delay Oregonator-based model, we address the qualitative properties (positivity, boundedness, and stability) of the model in terms of delayed-concentration and delayed-activation. Numerical results are presented to verify the properties of the model described by a qualitative/quantitative analysis.

Introduction to the dynamic self-organization of chemical systems

Following the presentation of basic concepts of nonlinear dynamics in chemistry in Part I, such dynamic instabilities like the oscillations, multistability, and spatiotemporal pattern formation are described in the present Part II for several real chemical systems, together with relevant kinetic models. Homogeneous systems include one of the Orban oscillators, involving catalytic oxidation of thiocyanates with hydrogen peroxide and the classical Belousov–Zhabotinsky reaction, together with its well-established Oregonator kinetic model. A heterogeneous electrochemical system involving the electroreduction of nickel thiocyanate complexes reveals bistability and oscillations interrelated as in the Boissonade–De Kepper model. Spatiotemporal patterns emerging due to the coupling between the chemical reaction and diffusion are shown based on: (1) the Belousov–Zhabotinsky reaction including its excitable characteristics, (2) the Brusselator as a source of the model Turing patterns also reported experimentally, and (3) periodic precipitation known as the Liesegang phenomena. Furthermore, the recently reported patterns formed in the systems subject to inhomogeneous temperature distribution were described. The self-organized nature of convection was shown based on both the classical Benard experiment and the convection driven electrochemically, including the “beating mercury heart” and the electrohydrodynamic formation of luminescent patterns. The course is completed with the brief description of the concept of deterministic chaos and the principle of its control as the modern subject of nonlinear dynamics. The appendix includes laboratory prescriptions for the most attractive experiments.

Facile One‐Pot Synthesis of Functional Giant Polymeric Vesicles Controlled by Oscillatory Chemistry

AbstractWe introduce a novel application of an oscillatory chemical reaction to the synthesis of block copolymers. The Belousov–Zhabotinsky (B‐Z) reaction is coupled with the polymerization of an amphiphilic block copolymer. Radicals generated in the B‐Z reaction initiate the polymerization between a polyethylene glycol (PEG) macroreversible addition‐fragmentation chain‐transfer agent and butyl acrylate monomers. The attachment of a hydrophobic block on PEG leads to self‐assembly and formation of spherical micelles. The nanoscale micelles transform into submicrometer vesicles and grow to giant vesicles as a consequence of the oscillatory behavior of the B‐Z reaction. The one‐pot synthesis of an amphiphilic di‐block copolymer and retention of oscillatory behavior for the B‐Z reaction with the formation of giant vesicles bring a new insight into possible pathways for the synthesis of active functional microreactors in the range from hundreds of nanometers to tens of micrometers.

Numerical simulation of artificial microswimmers driven by Marangoni flow

In the present paper the behavior of a single artificial microswimmer is addressed, namely an active droplet moving by Marangoni flow. We provide a numerical treatment for the main factors playing a role in real systems, such as advection, diffusion and the presence of chemical species with different behaviors. The flow field inside and outside the droplet is modeled to account for the two-way coupling between the surrounding fluid and the motion of the swimmer. Mass diffusion is also taken into account. In particular, we consider two concentration fields: the surfactant concentration in the bulk, i.e. in the liquid surrounding the droplet, and the surfactant concentration on the surface. The latter is related to the local surface tension, through an equation of state (Langmuir equation). We examine different interaction mechanisms between the bulk and the surface concentration fields, namely the case of insoluble surfactants attached to the surface (no exchange between the bulk and the surface) and soluble surfactants with adsorption/desorption at the surface. We also consider the case where the bulk concentration field is in equilibrium with the content of the droplet. The numerical results are validated through comparison with analytical calculations. We show that our model can reproduce the typical pusher/puller behavior presented by squirmers. It is also able to capture the self-propulsion mechanism of droplets driven by Belousov–Zhabotinsky (BZ) reactions, as well as a typical chemotactic behavior.

Design of a Tunable Self‐Oscillating Polymer with Ureido and Ru(bpy)3 Moieties

AbstractAn upper critical solution temperature (UCST)‐type self‐oscillating polymer was designed that exhibited rhythmic soluble–insoluble changes induced by the Belousov–Zhabotinsky (BZ) reaction. The target polymers were prepared by conjugating Ru(bpy)3, a catalyst for the BZ reaction, to ureido‐containing poly(allylamine‐co‐allylurea) (PAU) copolymers. The Ru(bpy)3‐conjugated PAUs exhibited a UCST‐type phase‐transition behavior, and the solubility of the polymer changed in response to the alternation in the valency of Ru(bpy)3. The ureido content influences the temperature range of self‐oscillation, and the oscillation occurred at higher temperatures than conventional LCST‐type self‐oscillating polymers. Furthermore, the self‐oscillating behavior of the Ru‐PAU could be regulated by addition of urea, which is a unique tuning strategy. We envision that novel self‐oscillating polymers with widely tunable soluble‐insoluble behaviors can be rationally designed based these UCST‐type polymers.

Cellular Automaton Belousov–Zhabotinsky Model for Binary Full Adder

The continuous increment in the performance of classical computers has been driven to its limit. New ways are studied to avoid this oncoming bottleneck and many answers can be found. An example is the Belousov–Zhabotinsky (BZ) reaction which includes some fundamental and essential characteristics that attract chemists, biologists, and computer scientists. Interaction of excitation wave-fronts in BZ system, can be interpreted in terms of logical gates and applied in the design of unconventional hardware components. Logic gates and other more complicated components have been already proposed using different topologies and particular characteristics. In this study, the inherent parallelism and simplicity of Cellular Automata (CAs) modeling is combined with an Oregonator model of light-sensitive version of BZ reaction. The resulting parallel and computationally-inexpensive model has the ability to simulate a topology that can be considered as a one-bit full adder digital component towards the design of an Arithmetic Logic Unit (ALU).

Tuning the Chemical Communication of Oscillating Microdroplets by Means of Membrane Composition

Synchronization of dynamic elements via chemical communication is a widespread phenomenon in nature and, hence, in many scientific fields, such as in biology, physics and chemistry, where systems capable of giving and receiving information are commonly found. In these systems, coupling and synchronization between elements is achieved by messenger molecules diffusing from one element to others that trigger and spread a chemical reaction. In nature, an important example of chemical communication and synchronicity can be found in cell populations, where the plasma membrane governs the trafficking of ions or molecules (among other mechanisms) into and out of the cells, thus dictating their collective dynamic. Herein, in a biomimetic approach, we used a microfluidic system to confine a “chemical information generator”, consisting of the far-from-equilibrium Belousov–Zhabotinsky (BZ) reaction, in the aqueous core of monodisperse simple emulsion microdroplets. These microdroplets were surrounded by an oil phase ...

Preparation and characterization of poly(AA-co-Fe(phen)3) self-oscillating gel

ABSTRACTA novel gel which undergoes an autonomic and periodical swelling–deswelling oscillation without any on–off switching of external stimuli was prepared by copolymerization of acrylic acid (AA) with iron (5-(acrylamide-N-yl)-1,10-phenanthroline) bis(1,10-phenanthroline) (Fe(phen)3) as the catalyst for the Belousov–Zhabotinsky (BZ) reaction. The swelling–shrinking and redox potential self-oscillating behaviors of the gels in an aqueous solution containing BZ substrates (except for the metal catalyst) were investigated. It was found that the swelling–shrinking amplitude of the gel was closely related to the content of the immobilized Fe(phen)3 catalyst. Moreover, the Turing patterns were observed first in the process of the volume self-oscillating.

Experimental investigation of a unidirectional network of four chemical oscillators pulse-coupled through an inhibitor

Dynamical synchronous modes in a network of four nearly identical chemical oscillators unidirectionally coupled via inhibitory pulse coupling with time delay τ (when a spike in one oscillator inhibits the next oscillator in the circle after time delay τ), are obtained experimentally. The Belousov–Zhabotinsky reaction is used as a chemical oscillator. The existence of four main modes is confirmed experimentally: in-phase (IP) oscillations; an anti-phase (AP) mode, in which any two neighboring oscillators have a phase shift equal to half of global period T; a walk mode (W), in which oscillators produce consecutive spikes in the direction of the connection with a phase shift between neighboring oscillators equal to T/4; and a walk-reverse mode (WR), when the oscillators produce consecutive spikes (with phase shift T/4), but in the direction opposite the connections (the mode opposite to the W mode). In addition to the main modes, OS modes in which at least one of the four oscillators is suppressed, and “2+1+1” modes in which two neighboring oscillators produce spikes simultaneously and the phases of the third and the fourth oscillators are shifted by T/3 and 2T/3, respectively, are found. It is shown that the modes found experimentally correspond to those found in simulations.

Andrey P. Antonchick

Angewandte Chemie International EditionVolume 56, Issue 40 p. 12042-12042 Author ProfileFree Access Andrey P. Antonchick First published: 10 May 2017 https://doi.org/10.1002/anie.201704212AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract “The secret of being a successful scientist is patience. My favorite name reaction is the Belousov–Zhabotinsky reaction ...” This and more about Andrey P. Antonchick can be found on page 12042. Andrey P. Antonchick The author presented on this page has recently published his 25th article since 2006 in Angewandte Chemie: “General Enantioselective C−H Activation with Efficiently Tunable Cyclopentadienyl Ligands”: Z.-J. Jia, C. Merten, R. Gontla, C. G. Daniliuc, A. P. Antonchick, H. Waldmann, Angew. Chem. Int. Ed. 2017, 56, 2429; Angew. Chem. 2017, 129, 2469. Date of birth: September 14, 1976 Position: Group leader, Technische Universität Dortmund E-mail: andrey.antonchick@tu-dortmund.de Homepage: http://antonchick.de ORCID: 0000-0003-0435-9443 Education: 2000 Undergraduate degree, Belarusian State University, Minsk 2005 PhD supervised by Prof. Dr. Vladimir Khripach (Institute of Bioorganic Chemistry of the National Academy of Sciences of Belarus) and Dr. Bernd Schneider (Max Planck Institute for Chemical Ecology, Jena) 2005–2008 Postdoctoral fellow with Prof. Dr. Magnus Rueping, University of Frankfurt 2008–2011 Postdoctoral fellow with Prof. Dr. Herbert Waldmann, Max Planck Institute of Molecular Physiology, Dortmund Awards: 2012 Thieme Chemistry Journals Award; 2017 visiting professorship, Peoples’ Friendship University of Russia Research: Reaction methodology, asymmetric catalysis, chemical biology Hobbies: Skiing, soccer The secret of being a successful scientist is patience. My favorite name reaction is the Belousov–Zhabotinsky reaction. My science “heroes” are Sofia V. Kovalevskaya, Alexander Fleming, Christiaan N. Barnard, Paul Ehrlich, Giordano Bruno, and many more. If I had one year of paid leave I would do some experiments in the lab. If I could be a piece of lab equipment, I would be a magnetic stir bar. The principal aspects of my personality are honesty and fairness. My favorite bands are Depeche Mode, The Cure, and Portishead. When I was eighteen I wanted to be a chemist. The most significant historic event of the past 100 years was space flight. My first experiment was the synthesis of nitrogen triiodide. My biggest inspiration is nature. My favorite times of day are early morning and late evening. My favorite way to spend a holiday is skiing. My 5 top papers: References 1“[1+1+1] Cyclotrimerization for the Synthesis of Cyclopropanes”: S. Manna, A. P. Antonchick, Angew. Chem. Int. Ed. 2016, 55, 5290; Angew. Chem. 2016, 128, 5376. (A radical cascade reaction for the simple synthesis of small rings.) 2“Cascade Multicomponent Synthesis of Indoles, Pyrazoles, and Pyridazinones by Functionalization of Alkenes”: K. Matcha, A. P. Antonchick, Angew. Chem. Int. Ed. 2014, 53, 11960; Angew. Chem. 2014, 126, 12154. (A general approach to heterocycle synthesis.) 3“Organocatalytic Oxidative Annulation of Benzamide Derivatives with Alkynes”: S. Manna, A. P. Antonchick, Angew. Chem. Int. Ed. 2014, 53, 7324; Angew. Chem. 2014, 126, 7452. (We demonstrated how transition-metal catalysts can be omitted in C−H bond functionalization.) 4“Metal-Free Cross-Dehydrogenative Coupling of Heterocycles with Aldehydes”: K. Matcha, A. P. Antonchick, Angew. Chem. Int. Ed. 2013, 52, 2082; Angew. Chem. 2013, 125, 2136. (One of the most practical reactions that was developed in my group.) 5“Palladium-Catalyzed Double C−H Activation Directed by Sulfoxides in the Synthesis of Dibenzothiophenes”: R. Samanta, A. P. Antonchick, Angew. Chem. Int. Ed. 2011, 50, 5217; Angew. Chem. 2011, 123, 5323. (Your first independent publication is like your first love!) Volume56, Issue40September 25, 2017Pages 12042-12042 ReferencesRelatedInformation

Protic Ionic Liquids for the Belousov-Zhabotinsky Reaction: Aspects of the BZ Reaction in Protic Ionic Liquids and Its Use for the Autonomous Coil-Globule Oscillation of a Linear Polymer.

Herein, we describe the physicochemical aspects of the Belousov-Zhabotinsky (BZ) reaction in hydrated protic ionic liquids (PILs) combined with different cations with a hydrogen sulfate ([HSO4-]) anion. PILs were prepared from the neutralization reactions of sulfuric acid with 13 different aliphatic amines. The amine structure was selected to investigate the effect of the number of active protons, alkyl chain length (hydrophilicity), and cationic linearity on the mechanism of the BZ reaction. The pKa values of PILs were significantly higher (pKa = 1.0-2.5) than those of inorganic acids (H2SO4 = -3.0; HNO3 = -1.4), the conventional proton source in a BZ reaction. A periodic redox oscillation was observed in Ru(bpy)3 when appropriate amounts of BZ reaction substrates (NaBrO3 oxidant; malonic acid reductant) were added to the hydrated PILs. A long-lasting BZ oscillation was realized when hydrophilic cations (ammonium, ethylammonium, and dimethylethylammonium) were employed. Interestingly, a large ΔA5000 (oscillation amplitude of absorbance for the scale of the oscillation stability observed after 5000 s from the initiation of the BZ reaction) was achieved for PILs possessing less than four carbon atoms in their cationic structure. The apparent BZ oscillation activation energy (Ea) in the hydrated PILs was estimated to be ∼40 kJ mol-1, which is 30 kJ mol-1 less than that observed in a conventional system. The catalytic reaction in the BZ reaction subprocess suppresses the total activation energy of the reaction. To realize long-lasting self-oscillating polymeric materials acting under milder condition, we demonstrated an autonomous coil-globule polymer chain transition (BZ-driven) that directly converts chemical energy to mechanical motion in hydrated PILs without freely diffusing Ru(bpy)3 metal catalyst. Ethylammonium hydrogen sulfate ([ea-H+][HSO4-]) is selected as the suitable proton source for the BZ reaction. A well-defined self-oscillating polymer that incorporated Ru(bpy)3 metal catalyst into the polymer backbone accompanied by good compatibility in hydrated [ea-H+][HSO4-] is successfully prepared by ATRP, followed by postmodification of the metal catalyst. The rhythmic solubility changes of the polymer under milder conditions, realized by combination with PILs, will expand the potential applications of PILs to novel functional materials.

Recent developments in self-oscillating polymeric systems as smart materials: from polymers to bulk hydrogels

As novel functional materials, we developed self-oscillating polymeric materials composed of synthetic polymers coupled with an oscillating chemical reaction, the so-called Belousov–Zhabotinsky (BZ) reaction.

Chemical memory with states coded in light controlled oscillations of interacting Belousov-Zhabotinsky droplets.

The information storing potential of droplets, in which an oscillatory, photosensitive Belousov-Zhabotinsky (BZ) reaction proceeds, is investigated experimentally. We consider coupled oscillations in pairs and triplets of droplets. Droplets are surrounded by a solution of lipids in decane. Oscillations synchronize via diffusion of an activator through a lipid bilayer. The reaction in each droplet can be individually controlled by illumination with blue light through an optical fiber. We found that in pairs of BZ droplets, only the in-phase and the forcing oscillation modes are stable, however switching between these modes is not reliable. In triplets of droplets, switching between two different, stable rotational modes (clockwise and anticlockwise) can be easily implemented. Therefore, such a system is an excellent candidate for a light controlled, reliable, one bit chemical memory unit.

Effect of polymer concentration on the lifetime and transmittance behavior of a self-oscillating polymer chain with a high lower critical solution temperature

In this study, we investigated the lifetime and self-oscillating behavior of a polymer chain with a high lower critical solution temperature (LCST). The polymer chain comprised 4-vinyl-4´-methyl-2,2´-bipyridinebis(2,2´-bipyridine)bis(hexafluorophosphate) ruthenium as catalyst for the Belousov–Zhabotinsky reaction and N-ethylacrylamide as the polymer main-chain with a high LCST when compared to N-isopropylacrylamide. We demonstrated that the self-oscillating behavior was significantly affected by the polymer concentration and measuring temperature. Moreover, we established that the lifetime of the transmittance self-oscillation can be predicted from the polymer concentration and measuring temperature.