Diols, fluorescent sensor

Kamati VV, Gao X, Gao S, Yang W, Ni W, Sankar S, Wang B. A glucose-selective fluorescence sensor based on boronic acid-diol recognition. Bioorganic and Medicinal Chemistry Letters 2002, 12, 3373-3377. 

Zinc carboxylate interactions have been exploited as part of a fluorescent molecular sensor for uronic acids. The sensors feature two interactions coordination of the carboxylate to the zinc and a boronic acid diol interaction.389 Photoluminescent coordination polymers from hydrothermal syntheses containing Zn40 or Zn4(OH)2 cores with isophthalate or fumarate and 4,4 -bipyridine form two- and three-dimensional structures. Single X-ray diffraction of both dicarboxylates identified the network structure.373... 

A new PET-based chemosensor for uronic and sialic acids utilizing the cooperative action of boronic acid and metal chelate was reported by Shinkai and co-workers. This group synthesized a novel fluorescent chemosensor molecule bearing both an o-aminomethylphenylboronic acid group for diol binding to a saccharide and a l,10-phenanthroline-Zn(II)chelate moiety for the carboxylate binding, which enables this sensor to discriminate between neutral monosaccharides and acidic compounds [110],... 

More recently the boronic acid PET system has been used in combination with other binding sites. The D-glucosamine selective fluorescent systems 31 and 32 based on a boronic acid and azacrown ether have been explored [73,74], Sensors 31 and 32 consist of monoaza-18-crown-6 ether or monoaza-15-crown-5 as a binding site for the ammonium terminal of D-glucosamine hydrochloride, while a boronic acid serves as a binding site for the diol (carbohydrate) part... 

Boronic acids RB(OH)2, boronic esters RB(OR)2, and triorganoboranes R3B have been studied extensively for the selective recognition of anions. " Moreover, arylboronic acids have proven highly useful for sensing of saccharides based on the facile formation of esters with diols, thus providing an excellent alternative to more commonly employed synthetic molecular receptors based on hydrogenbonding interactions. Absorption and fluorescence spectroscopy, circular dichroism, and cyclic voltammetry have all been successfiilly used as detection methods for organoboron sensors. 

Attachement of FLAB to a streptavidin-appended gold surface was confirmed by both SPR and concomitant fluorescence snrface plasmon resonance (f-SPR). Exposure of the surface thus prepared to BHQ-diol gave rise to both fluorescence qnenching and an SPR response demonstrating the potential for the dual techniques for SPR and fluorescence to work in nnison in a sensor regime under the guise of f-SPR. 

Boronic acid-based biosensors to detect saccharides The recognition of saccharides, especially o-glucose, is of particular interest, owing to their correlation to diabetes and human cancers. The specific recognition of boronic acid for -diols provides a sensing selectivity. In the sugar sensors based on boronic acids (Figure 8), fluorescent, colorimetric, or electrochemical methods can be used as readout units. 

As we have discussed, the strength of this interaction is a central feature in many fluorescent PET sensors, where the N-B interaction plays a pivotal role in signalling the binding event. If the interaction were much stronger, then the binding of a diol would not be able to disrupt the N B interaction sufficiently so as to modulate a change in fluorescence. By the same token, if the interaction were much weaker, then there would be no significant intramolecular N-B interaction to disrupt in the first place. 

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