Boronic acids self-assembly

Sarson et al. combined two kinds of reversible interactions, namely, boronic acid-diol and metal-pyridine interactions, to generate self-assembled polymers. A1 2 mixture of magnesium dicatechol porphyrin 41 and pyridine-3-boronic acid self-assembles into a polymer. The molecularweightwas estimated to be 10 by light scattering measurements. 

A judicious combination of plural dihydroxyboryl and multiple hydroxyl components can lead to the formation of various boronate-based self-assemblies. Furthermore, the surfaces of such ensembles are composed of boronate esters with Lewis-acidic characteristics, and this opens up new possibilities for the use of scaffolds in various applications. In this context, we envisaged that such self-assemblies might have applications in the fabrication of organic-inorganic hybrid catalysts. The development of new types of catalyst for fine chemical synthesis is urgently required from the viewpoint of sustainable chemistry and green organic synthesis in particular, Au nanoparticle (Au NP)-catalysed fine chemical synthesis has the potential for practical use in industry. ... 

Shinkai (65) exploited the boronic acid-diol motif mentioned above to self-assemble a polymer based on pyridine-magnesium porphyrin interactions. In this case, the evidence for polymerization comes from lightscattering experiments in dilute solution which yielded an average molecular weight of 109 g mol-1 for this system. 

There are many kinds of capsules but few have the capacity to position co-guests in predictable orientations. We used the ability of 1.24.1 to do so, and applied it to evaluate hydrogen-bonding interactions between boronic acids, carboxylic acids, and primary amides [52], The phenyl boronic acids are useful as components of covalently self-assembled systems [53], and we found that the p-methyl, methoxy, ethyl, and isopropyl derivatives all fit as symmetrical dimers inside I.24.I. The structure of the boronic acid dimer has been debated but a recent theoretical study found the doubly hydrogen-bonded exo/endo conformer (Fig. 10) to be lowest in... 

Shinkai reported the formation of the cyclic dimer 21 upon mixing a 1 1 mixture of a meso-dicatechol zincporphyrin and pyridine-3-boronic acid dimethyl ester in CH2CI2 [78]. The dimerization constant iCsa = 1.1x10 mol 1 and the reference constant iCinter = 340 mol" 1, yield an EM 0.1 moll The authors claimed complete formation of the dimer 21, however, the product EMiCinter/ 17 does not satisfy the condition for complete self-assembly expressed by Eq. 22. According to the plot in Fig. 13 the weight fraction of the dimer can be in no case higher than ca. 0.9. 

Kobayashi investigated a self-assembled boronic ester cavitand capsule for photochemical reaction of 2,6-diacetoxyanthracene. Tsuda found a self-assembled helical anthracene nanofiber in a vortex. Chou examined rotational behaviors and fluorescence energy transfer of N-l- and N-2-anthryl succinimide derivatives. " Reversible photoinduced twisting of molecular crystal microribbons via [4 - - 4] photocycloaddition of 9-anthra-cenecarboxylic acid. Reversible single walled carbon nanotubes of 1,3-bis(9-anthracenylmethyl)imidazolium chloride was examined as a functionalized anthracene salts.Karatsu reported the intramolecular photodimerization of 9-substituted anthracene derivatives (253) tethered by oligosilanes giving [4 + 4] and [2 - - 4]cycloadducts (254), (255), and (256). ... 

Membranes and Molecular Assemblies The Synkinetic Approach 6 Calixarenes Revisited 7 Self-assembly in Supramolecular Systems 8 Anion Receptor Chemistry 9 Boronic Acids in Saccharide Recognition 10 Calixarenes An Introduction, 2nd Edition 11 Polymeric and Self Assembled Hydrogels From Fundamental Understanding to Applications 12 Molecular Logic-based Computation 13 Supramolecular Systems in Biomedical Fields 14 Synthetic Receptors for Biomolecules Design Principles and Applications... 

The interaction of boronic acids with saccharides " and anions has been extensively investigated, and boronic acids have also been exploited in a range of applications as diverse as sensing and separation, " NMR (nuclear magnetic resonance) shift reagents, functional polymers for electrophoresis, and molecular self-assembled capsules and materials. 

Fossey and James have also developed a self-assembled boronic acid hybrid system for surface-plasmon-enhanced fluorescence detection of quencher-labeled diols. Snr-face plasmon excitation of the read-out fluorophore has dual advantages firstly, surface plasmon resonance (SPR) may be concomitantly conducted, and no incident light... 

Kubo and James have shown that it is possible to use anion-directed self-assembly to control the formation of molecular capsules between boronic acid and diol trimeric... 

R. Nishiyabu, Y. Kubo, T. D. James, J. S. Fossey, Chem. Commun. 2011, 47, 1124—1150. Boronic acid building blocks tools for self assembly. 

Polymer Self-Assembly Mediated by Boronic Acid... 

FRET donor and acceptor can also be incorporated into the self-assembled nanofibers of supramolecular hydrogels. In this way Ikeda et developed a gel-based fluorocolorimetric sensor for polyols. The acceptor is boronic acid-appended. In the presence of polyols, it forms boronate ester complexes with the polyols, becomes negatively charged and more hydrophilic, and therefore migrates from the hydrophobic site. The increased distance between the donor and acceptor results in the fluorescence color change, from which the presence of polyols can be detected. 

Figure 11.25 Self-assembly of the NCs, the polymerizable surfactant OVDAC, and boronic acid and acrylamide monomers for the preparation of a fluorescence nanosensor. (Reproduced from ref. 141 with permission. Copyright 2014, John Wiley Sons, Ltd.)...

L. Liang and Z. Liu, A self-assembled molecular team of boronic acids at the gold surface for specific capture of cis-diol biomolecules at neutral pH, Chem. Commun., 2011, 47(8), 2255-2257. 

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