A method has been proposed to assess cooperativity in self-assembly processes. The is based on a clear distinction between intermolecular and intramolecular processes which are compared with the corresponding reference reactions. It applied two classical cases, namely of helicates porphyrin ladders, by using data previously published groups Lehn Anderson, respectively. Contrarily conclusions authors, pointing out driven positive cooperativity, here presented indicates both cases absence...

Vive la différence: The distinction between different types of cooperativity is essential for understanding the fundamentals involved. three title cooperative effects arise from interplay intermolecular binding interactions, presence one or more intramolecular and, in latter case, their possible interplay. A master equation stability an assembly outlined that takes into account all cooperativity. Detailed facts importance to specialist readers are published as "Supporting Information". Such...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMacrocyclization under thermodynamic control. A theoretical study and its application to the equilibrium cyclooligomerization of .beta.-propiolactoneGianfranco Ercolani, Luigi Mandolini, Paolo Mencarelli, Stefano RoelensCite this: J. Am. Chem. Soc. 1993, 115, 10, 3901–3908Publication Date (Print):May 1, 1993Publication History Published online1 May 2002Published inissue 1 1993https://doi.org/10.1021/ja00063a008RIGHTS & PERMISSIONSArticle...

The supramolecular polymerization of two AB-type monomers capable hydrogen-bond-mediated A x B heterocoupling and homocoupling is discussed. based on the strong interaction between self-dimerizing 2-ureido-pyrimidinone (UPy) 2,7-diamido-1,8-naphthyridine (NaPy). In an effort to reduce "self-stoppered" effect that inherently present in these polymerizations we used a novel ureido-pyrimidinone substituted with dibutylamino group at pyrimidinone ring. As result substitution, dimerization...

The translocation of biopolymers through pores and channels plays a fundamental role in numerous biological processes. We describe here the mechanism threading series polymer chains synthetic macrocycle, which mimics these natural polymers involves kinetically favorable "entron" effect, is associated with initial filling cavity by end polymer. A preassociation between outside macrocycle induces process loops back into macrocycle. This looping results accelerated rates unidirectional motion...

We study the effect of pendent methyl groups on alkaline stability model anion exchange polymers based poly(2,6-dimethyl-1,4-phenylene)oxide (PPO) with grafted trimethylammonium groups. The polymer backbone is modified varying synthesis procedure: by bromination route, ionomeric ammonium are inserted structural group PPO (Br-PPO-TMA), while chloromethylation route attached in ortho-position to (Cl-PPO-TMA). properties membranes studied NMR and FTIR spectroscopy, thermogravimetry, water...

A theoretical treatment of self-assembly macrocyclizations occurring under thermodynamic control is presented. The fundamental quantities on which the based are effective molarity self-assembling cyclic n-mer (EMn) and equilibrium constant for intermolecular model reaction between monofunctional reactants (Kinter). Knowledge these allows evaluation distribution curve macrocycle. In order to take place two conditions required: (i) macrocycle must have an EM much larger than that other...

Soai, so good: The Soai reaction is the sole reported case of amplifying asymmetric autocatalysis. A mechanism proposed for this reaction, supported by first-principle calculations, clarifying not only reasons detected chiral induction and amplification, but also roles performed isopropyl groups, γ-pyridinic nitrogen atoms, δ-substituent.

Previous DFT calculations provided support to the proposal that Soai reaction involves a mechanism in which dimer catalysts serve as templates for of two molecules dialkylzinc with aldehyde so reproduce themselves (ref 11). Here it is shown that, from point view formal kinetics, this can be reduced general model, dubbed extended has Blackmond-Brown model particular case. Depending on interplay kinetic constants, give rise either chiral amplification or depletion. Calculations constants at...

We demonstrate here the use of 2-(4-chlorophenyl)-2-cyanopropanoic acid (CPA) and nitroacetic (NAA) as convenient chemical fuels to drive dissipative operation DNA-based nanodevices. Addition either fuel acids a water solution initially causes rapid transient pH decrease, which is then followed by slower increase. have employed such low-to-high cycles control in way two model nanodevices: DNA nanoswitch undergoing time-programmable open-close-open motion, receptor able release-uptake cargo...

Abstract DNA-templated synthesis takes advantage of the programmability DNA-DNA interactions to accelerate chemical reactions under diluted conditions upon sequence-specific hybridization. While this strategy has proven advantageous for a variety applications, including sensing and drug discovery, it been so far limited use nucleic acids as templating elements. Here, we report rational design DNA templated controlled by specific IgG antibodies. Our approach is based on co-localization...

Abstract We demonstrate here the use of DNA repair enzymes to control assembly DNA‐based structures. To do so, we employed uracil‐DNA glycosylase (UDG) and formamidopyrimidine (Fpg), two involved in base excision (BER) pathway. designed responsive nucleic acid modules containing mutated bases (deoxyuridine or 8‐oxo‐7,8‐dihydroguanine recognized by UDG Fpg, respectively) that, upon enzyme activity, release a strand that induces self‐assembly tiles into tubular The approach is programmable,...

Anion-conducting organic–inorganic polymers (OIPs), constructed using metal–organic framework (MOF)-like structures with non-toxic, non-rare catalytic metals (Fe3+, Zr4+), have been developed. The incorporation of MOF-like imparts porosity to the polymers, classifying them as porous organic (POPs). combination between activity, ion conduction, and allows material act one-component electrodes. A high activity is expected since entire surface area contributes electrocatalysis, rather than...

A model treating the competition, under thermodynamic control, between self-assembly and nonlinear random polymerization is presented. The fundamental quantities on which treatment based are effective molarity (EM) of assembly equilibrium constant for intermolecular reaction monofunctional reactants (Kinter). Knowledge these allows evaluation distribution curve self-assembling complex. In order to take place, product KinterEM must be no lower than a limit value easily computable basis simple...

[reaction: see text] A product and time-resolved kinetic study of the effect ring substitution on reactivity 1,1-diarylalkoxyl radicals has been carried out. The undergo an O-neophyl shift to give isomeric 1-aryl-1-aryloxyalkyl from which corresponding aromatic ketones are formed. rearrangement rate constants influenced by substitution, increasing in presence electron-withdrawing substituents decreasing electron-donating ones. From results studies, following migratory aptitudes have...

Statistical mechanics predicts that the design of pure organized heteropolymetallic chains metal ions bound to linear receptors depends on controlled deviations from mixing rule DeltaE(MiMj) = 1/2 (DeltaE(MiMi) + DeltaE(MjMj)), whereby is intramolecular intermetallic interaction between neighboring i and j along receptor. A thorough investigation polymetallic trivalent lanthanide triple-stranded helicates shows such are amplified by an increase in nuclearity final complexes thus easily...

From a kinetic analysis of the "dimer model", which is most prominent mechanism Soai reaction, an equation derived predicting amplification enantiomeric excess as function initial conditions. The role played by enantioselectivity catalyst-product also taken into account. Comparison with experimental data obtained at 0 degrees C et al. shows that predicted excesses are lower than values up to four orders magnitude, and thus revision dimer model in low-temperature regime warranted. A including...

Abstract The mechanism of the Soai reaction has been thoroughly investigated at M05‐2X/6‐31G(d) level theory, by considering ten energetically distinct paths. study indicates fully enantioselective catalytic cycle homochiral dimers to be dominant mechanism. Two other cycles are shown both important for correct understanding reaction. These heterochiral dimer and non‐enantioselective dimers. former proved not really competitive with principal cycle, as required manifest chiral amplification,...

The contribution of the solvation energies to assembly polynuclear helicates reduces free energy intermetallic repulsion, DeltaE(MM), in condensed phase such an extent that stable D(3)-symmetrical tetranuclear lanthanide-containing triple-stranded [Ln(4)(L4)(3)](12+) are quantitatively produced at millimolar concentrations, despite twelve positive charge borne by these complexes. A detailed modelling formation constants using statistical factors, adapted self-assembly processes involving...

Abstract In this work, we report that 2‐cyano‐2‐phenylpropanoic acid and its p ‐Cl, ‐CH 3 ‐OCH derivatives can be used as chemical fuels to control the geometry of calix[4]arene scaffold in cone conformation. It is shown that, under action fuel, platform assumes a “locked” shape with two opposite aromatic rings strongly convergent other divergent (“pinched cone” conformation). Only when fuel exhausted, returns resting, “unlocked” shape. Remarkably, duration state controlled at will by...

Predictable and time-programmable sequences of the kind pH_1(high)–pH_2(low)–pH_3(high) in water solution are obtained by a judicious choice concentration nitroacetic acid undergoing decarboxylation.

Abstract We report here the rational design and optimization of an antibody‐responsive, DNA‐based device that enables communication between pairs otherwise non‐interacting proteins. The is designed to recognize bind a specific antibody and, in response, undergo conformational change leads release DNA strand, termed “translator,” regulates activity downstream target protein. As proof principle, we demonstrate antibody‐induced control proteins thrombin Taq polymerase. resulting strategy...

Herein, we present a generalizable and versatile strategy to engineer synthetic DNA ligand-binding devices that can be programmed load release specific ligand at defined temperature. We do so by re-engineering two model DNA-based receptors: triplex-forming bivalent receptor recognizes sequence an ATP-binding aptamer. The temperature which these receptors load/release their ligands finely modulated controlling the entropy associated with linker connecting domains. availability of set tunable...