Boronic Acid

NSFC [20835005, 91127019]By designing a long and hydrophobic stilbeneboronic acid (STDBA) and allowing it to be included within the cavity of gamma-cyclodextrin (gamma-CyD) we succeeded in developing a fluorescent 2 : 2 STDBA-gamma-CyD ensemble that shows a selective and sensitive response toward glucose in aqueous solutions, with satisfactory application in artificial urine samples

We report a new scheme for chiral recognition using coordination polymers of Ag + with a chiral thiol ligand that contains a binding group. N-Benzoyl-L-cysteine ethyl ester equipped with a boronic acid group at the para position of the phenyl ring forms coordination polymers with Ag + in alkaline aqueous solutions that exhibit excellent selectivity toward a D-glucose enantiomer over Lglucose, while the coordination polymers from the D-cysteine-based thiol ligand are specific for L-glucose. It is assumed that a conformation change occurs upon interaction of a saccharide molecule with the polymeric chain receptor, for which the next binding is promoted, leading to the highly effective chiral recognition, despite the flexible nature of the polymeric receptor.

We report a strategy for enhanced performance of fluorescent sensing of biologically relevant species that often binds with natural receptors via multiple interactions. We propose to make the fluorescent sensory molecule to form H-aggregates that its emission is quenched leaving a low background, and upon binding to a biologically relevant species the aggregates are switched to another form in which the fluorescent species is better protected to afford a stronger emission signal. Meanwhile, the aggregated fluorescent dyes afford multiple interactions with the sensing species that requires multiple binding sites. The lower background, stronger binding and stronger signal would therefore lead to a much higher sensing performance, as improved selectivity would also result in along the signal amplification. We thus designed a near-IR cyanine dye bearing two boronic acid groups (Cy-BA) for fluorescent sensing of ATP, that the boronic acid groups in the dye molecule bind to the cis-diol m...

Binding of the fluoride ion triggers aggregation of a pyreneboronic acid-catechol ensemble in acidic aqueous solutions, giving rise to intense excimer emission, allowing for sensitive fluoride ion sensing at ppm levels, with an apparent fluoride binding constant higher than 10(3) M(-1) which is unprecedented for boronic acid sensors in water.

Substantially enhanced monosaccharide fluorescent sensing in aqueous solutions using a simple phenylboronic acid receptor is achieved by coupling the classic strategy based on saccharideboronic acid interaction with catalytic Suzuki homocoupling reaction.

2 strains. Therefore, novel active structures with new modes of action are required. We describe a web application called AntiBac-Pred aimed to help users in the rational selection of the chemical compounds for experimental studies of antibacterial activity. This application is developed using antibacterial activity data available in ChEMBL and PASS software. It allows users to classify chemical structures of interest into growth inhibitors or non-inhibitors of 353 different bacteria strains, including both resistant and non-resistant ones.

Existing data on structures and biological activities are limited and distributed unevenly across distinct molecular targets and chemical compounds. The question arises if these data represent an unbiased sample of the general population of chemicalbiological interactions. To answer this question, we analyzed ChEMBL data for 87,583 molecules tested against 919 protein targets using supervised and unsupervised approaches. Hierarchical clustering of the Murcko frameworks generated using Chemistry Development Toolkit showed that the available data form a big diffuse cloud without apparent structure. In contrast hereto, PASS-based classifiers allowed prediction whether the compound had been tested against the particular molecular target, despite whether it was active or not. Thus, one may conclude that the selection of chemical compounds for testing against specific targets is biased, probably due to the influence of prior knowledge. We assessed the possibility to improve (Q)SAR predictions using this fact: PASS prediction of the interaction with the particular target for compounds predicted as tested against the target has significantly higher accuracy than for those predicted as untested (average ROC AUC are about 0.87 and 0.75, respectively). Thus, considering the existing bias in the data of the training set may increase the performance of virtual screening.

Organoboron compounds are well known building blocks for many organic reactions. However, under basic conditions, polyfluorinated aryl boronic acid derivatives suffer from instability issues that are accelerated in compounds containing an ortho‐fluorine group, which result in the formation of the corresponding protodeboronation products. Therefore, a considerable amount of research has focused on novel methodologies to synthesize these valuable compounds while avoiding the protodeboronation issue. This review summarizes the latest developments in the synthesis of fluorinated aryl boronic acid derivatives and their applications in cross‐coupling reactions and other transformations.magnified image

In the crystal, the title compound, C 12 H 19 BO 4 , exists as a centrosymmetric O-HÁ Á ÁO hydrogen-bonded dimer. Dimers are linked via C-HÁ Á ÁO hydrogen bonds, generating an infinite zigzag chain oriented parallel to [111]. The chains are assembled, giving sheets aligned parallel to (211) and interconnected by weak C-HÁ Á Á interactions, producing a threedimensional network. Data collection Bruker APEXII diffractometer Absorption correction: multi-scan (SORTAV; Blessing, 1995) T min = 0.986, T max = 0.992 12243 measured reflections 2950 independent reflections 1981 reflections with I > 2(I) R int = 0.024 Refinement R[F 2 > 2(F 2 )] = 0.033 wR(F 2 ) = 0.081 S = 0.90 2950 reflections

AbstractÐBoronic acids bind with compounds containing diol moieties with high af®nity through reversible boronate formation. However, the conditions that foster tight binding between the diol and the boronic acid are not well understood. Also, due to the multiple ionic states of both the boronic acid and boronate ester, the equilibrium constants reported in the literature have not always been strictly de®ned, and therefore there is a lack of `comparability' between the reported values. To address these issues, we have developed a method for examining boronate ester stability using the ¯uorescent reporter Alizarin Red S. We have used this system to determine the binding constants of a series of diols, and as a basis from which to derive a number of relationships that correlate the various equilibrium constants in the literature.

Molecules containing the aryl-cyanovinyl moiety are known as tyrphostins because of their action inhibiting proteins from the tyrosine kinase family, an interesting target for the development of anticancer and trypanocidal drugs. In the present work, E-(cyanovinyl)benzeneboronic acids were synthesized by Knoevenagel condensations without catalysts, and in water; through a simple protocol that completely avoided the use of organic solvents in the synthesis and in the work-up process. In vitro anticancer and trypanocidal activities of the synthesized boronic acids were also evaluated demonstrating that the introduction of the boronic acid functionality can improve the activity of the boronic tyrphostins. In silico target fishing using a Chemogenomic approach suggested the tyrosine-phosphorylation-regulated kinase 1a (DYRK1A) as a potential target for some of the designed compounds.

In this article ferrocene monoamino phenyl boronic acid (FcMAPBA) and ferrocene diamino phenyl boronic acid (FcDAPBA) were synthesized and characterized by 1 H NMR and FTIR. Particular emphasis is given to cis-diol and saccharide binding affinities with ferrocene amino phenyl boronic acid (FcAPBAs) which was investigated by 1 H NMR and CV (using sorbitol). Free and bound forms of derivatives were depicted from disappearance of boronic acid hydroxyls signal in 1 H NMR spectra. The presence of two discrete peaks in the CV curves is in agreement with 1 H NMR spectra, as the indication of cis-diol binding with saccharides. It was also proposed that this approach using potential shift difference in CV curves can be applied for surface confined glycated molecules detection.

Boronic acid, which can bind chemo-selectively and reversibly to diols, could be used for the early detection of bacteria through its affinity-binding reaction with diol groups on the bacterial cell wall. Herein, we describe the use of a diol-modified fluorescent probe (DYE) conjugated to a nanosensor consisting of phenylboronic acid-functionalized fluorescent carbon dot (FCD) to allow quenching via the Förster resonance energy transfer (FRET) process. Phenylboronic acid is well-known for its preferential affinity for diol-containing molecules through cyclic ester bond formation. Therefore, in the presence of glucosecontaining bacteria, the DYE in the cyclic ester form will be released from the FCD and replaced by the bacterial cell forming a new cyclic boronate ester bond with the nanoparticle, inducing recovery of the fluorescence. Quantitatively, the system's detection performance at various bacterial concentrations (10 1 -10 7 CFU/mL) reached ∼100% after 60 min, indicating that the high binding affinity of the diol moeity on the peptidoglycan (sugar)-rich bacteria was enough to displace the DYE from the boronic acid-functionalized FCD platform. Our facile and tunable fluorescence switch-on system was tested for its ability to detect bacteria in water from a contaminated river. Incredibly, the system was most successful in detecting bacteria in the contaminated river water, thus proving it to be a less expensive and more robust affinity biosensor for the detection of contaminating pathogens in various chemoselective ligand-based environments.

Boronic acid, which can bind chemo-selectively and reversibly to diols, could be used for the early detection of bacteria through its affinity-binding reaction with diol groups on the bacterial cell wall. Herein, we describe the use of a diol-modified fluorescent probe (DYE) conjugated to a nanosensor consisting of phenylboronic acid-functionalized fluorescent carbon dot (FCD) to allow quenching via the Förster resonance energy transfer (FRET) process. Phenylboronic acid is well-known for its preferential affinity for diol-containing molecules through cyclic ester bond formation. Therefore, in the presence of glucosecontaining bacteria, the DYE in the cyclic ester form will be released from the FCD and replaced by the bacterial cell forming a new cyclic boronate ester bond with the nanoparticle, inducing recovery of the fluorescence. Quantitatively, the system's detection performance at various bacterial concentrations (10 1 -10 7 CFU/mL) reached ∼100% after 60 min, indicating that the high binding affinity of the diol moeity on the peptidoglycan (sugar)-rich bacteria was enough to displace the DYE from the boronic acid-functionalized FCD platform. Our facile and tunable fluorescence switch-on system was tested for its ability to detect bacteria in water from a contaminated river. Incredibly, the system was most successful in detecting bacteria in the contaminated river water, thus proving it to be a less expensive and more robust affinity biosensor for the detection of contaminating pathogens in various chemoselective ligand-based environments.

The carbonized boronic acid-conjugated fluorescent carbon nanoparticles (FNPs) were crosslinked with carbonized dopamine-conjugated hyaluronic acid (HA) via the diol boronic acid-linked catechol groups [C-FNP] as extracellular targeting ligands and pH responsiveness. Into that C-FNP, the redox-responsive MnO 2 nanosheets were loaded to demonstrate quenching effect, which recovered after glutathione (GSH) treatment. The MnO 2 -loaded C-FNP showed excellent stability and tumor-targeting ability guided to the localized tumor using "on-off" fluorescent switch. Furthermore, paclitaxel (PTX) inside the MnO 2 -loaded C-FNP performed in vitro and in vivo bioimaging and chemotherapeutic activities analyzed towards cancer and non-cancerous cells.

5-(4-bromophenyl)-4,6-dichloropyrimidine was arylated with several aryl/heteroaryl boronic acids via the Suzuki cross-coupling reaction by using Pd(0) catalyst to yield novel pyrimidine analogs (3a-h). It was optimized so that good yields were obtained when 5 mol % Pd(PPh3)4 was used along with K3PO4 and 1,4-Dioxane. Electron-rich boronic acids were succeeded to produce good yields of products. Density functional theory (DFT) calculations were also applied on these new compounds to analyze their reactivity descriptors and electronic and structural relationship. According to DFT studies, compound 3f is the most reactive one, while 3g is the most stable one. As per DFT studies, the hyperpolarizability (β) values of these compounds do not show them as very good non-linear optical (NLO) materials. Compound 3f has the highest β value among all the compounds under study but still it is not high enough to render it a potent NLO material.

Three new photochromic compounds, 3-(2,5-dimethyl-3-thienyl)-4-(2-phenyl-5-methyl-4-thiazolyl)-1,8-napht- , were synthesized and their photochromic properties were studied. Compound 1-O was synthesized by two consecutive Suzuki coupling reactions using 2,5dimethylthiophene-3-boronic acid and 5-methyl-2-phenylthiazole-4-boronic acid. Photochromic compounds 2-O and 3-O were prepared by multistep reactions starting with 3-iodo-4-bromo-1,8-naphthalic anhydride and 2,5-dimethylthiophene-3-boronic acid or 2-phenyl-5-methylthiazole-4-boronic acid. All photochromic compounds showed a color change from colorless (or light yellow) to blue-green, purple, or orange colors (depending on the nature of the structures) on exposure to UV light at 365 nm in ethyl acetate solutions. The colored solutions can be reversed to the original colorless (or light yellow) solution by exposure to visible light at 530 nm.

Poly(methyl methacrylate) nanoparticles containing 4-vinylphenyl boronic acid were synthesized in one pot by surfactant-free emulsion polymerization. The nanoparticles were characterized by scanning electron microscopy and dynamic light scattering. Boron content in the nanoparticles was confirmed by electron-dispersive X-ray spectroscopy. In polymerization process, several co-monomer ratios were studied in order to obtain optimum nanoparticle size. Average hydrodynamic diameter and polydispersity index of nanoparticles versus variation of acetone percentage in the solvent mixture and total monomer concentration were investigated. The effect of boronic acid concentration in the monomer mixture on nanoparticle size and size distribution was also reported. Without further functionalization to the nanoparticles, the catechol dye, alizarin red S, was bound to boronic acid-containing nanoparticles. These nanoparticles behave as a nanosensor by which glucose or fructose can be easily detected. Dye-containing nanoparticles were undertaken displacement reaction by glucose or fructose. The glucose or fructose content was also monitored by UV-Visible spectrophotometer. Furthermore, cytotoxicity studies of boronic acid-carrying poly(methyl methacrylate) nanoparticles were carried out in 3T3 cells, which showed no toxicity effect on the cells.

The subject of this study is vitrimers, a class of thermoset polymers with exchangeable covalent bonds, with a focus on their ability to improve material durability in the aerospace, civil infrastructure, and elastomer technology industries while requiring minimal intervention. The

Molecular cruciforms are X-shaped systems in which two conjugation axes intersect at a central core. If one axis of these molecules is substituted with electron-donors, and the other with electron-acceptors, cruciforms' HOMO will localize along the electron-rich and LUMO along the electron-poor axis. This spatial isolation of cruciforms' frontier molecular orbitals (FMOs) is essential to their use as sensors, since analyte binding to the cruciform invariably changes its HOMO-LUMO gap and the associated optical properties. Using this principle, Bunz and Miljanić groups developed 1,4-distyryl-2,5-bis(arylethynyl)benzene and benzobisoxazole cruciforms, respectively, which act as fluorescent sensors for metal ions, carboxylic acids, boronic acids, phenols, amines, and anions. The emission colors observed when these cruciform are mixed with analytes are highly sensitive to the details of analyte's structure and -because of cruciforms' charge-separated excited states -to the solvent in which emission is observed. Structurally closely related species can be qualitatively distinguished within several analyte classes: (a) carboxylic acids; (b) boronic acids, and (c) metals. Using a hybrid sensing system composed from benzobisoxazole cruciforms and boronic acid additives, we were also able to discern among structurally similar: (d) small organic and inorganic anions, (e) amines, and (f) phenols. The method used for this qualitative distinction is exceedingly simple. Dilute solutions (typically 10 -6 M) of cruciforms in several off-the-shelf solvents are placed in UV/Vis vials. Then, analytes of interest are added, either directly as solids or in concentrated solution. Fluorescence changes occur virtually instantaneously and can be recorded through standard digital photography using a semi-professional digital camera in a dark room. With minimal graphic manipulation, representative cut-outs of emission color photographs can be arranged into panels which permit quick nakedeye distinction among analytes. For quantification purposes, Red/Green/Blue values can be extracted from these photographs and the obtained numeric data can be statistically processed.

Molecular cruciforms are X-shaped systems in which two conjugation axes intersect at a central core. If one axis of these molecules is substituted with electron-donors, and the other with electron-acceptors, cruciforms' HOMO will localize along the electron-rich and LUMO along the electron-poor axis. This spatial isolation of cruciforms' frontier molecular orbitals (FMOs) is essential to their use as sensors, since analyte binding to the cruciform invariably changes its HOMO-LUMO gap and the associated optical properties. Using this principle, Bunz and Miljanić groups developed 1,4-distyryl-2,5-bis(arylethynyl)benzene and benzobisoxazole cruciforms, respectively, which act as fluorescent sensors for metal ions, carboxylic acids, boronic acids, phenols, amines, and anions. The emission colors observed when these cruciform are mixed with analytes are highly sensitive to the details of analyte's structure and -because of cruciforms' charge-separated excited states -to the solvent in which emission is observed. Structurally closely related species can be qualitatively distinguished within several analyte classes: (a) carboxylic acids; (b) boronic acids, and (c) metals. Using a hybrid sensing system composed from benzobisoxazole cruciforms and boronic acid additives, we were also able to discern among structurally similar: (d) small organic and inorganic anions, (e) amines, and (f) phenols. The method used for this qualitative distinction is exceedingly simple. Dilute solutions (typically 10 -6 M) of cruciforms in several off-the-shelf solvents are placed in UV/Vis vials. Then, analytes of interest are added, either directly as solids or in concentrated solution. Fluorescence changes occur virtually instantaneously and can be recorded through standard digital photography using a semi-professional digital camera in a dark room. With minimal graphic manipulation, representative cut-outs of emission color photographs can be arranged into panels which permit quick nakedeye distinction among analytes. For quantification purposes, Red/Green/Blue values can be extracted from these photographs and the obtained numeric data can be statistically processed.

The structures of the class C b-lactamase from Enterobacter cloacae 908R alone and in complex with a boronic acid transition-state analogue were determined by X-ray crystallography at 2.1 and 2.3 Å, respectively. The structure of the enzyme resembles those of other class C b-lactamases. The structure of the complex with the transition-state analogue, iodo-acetamido-phenyl boronic acid, shows that the inhibitor is covalently bound to the ac-

Penicillin-binding proteins (PBPs) are DD-peptidases involved in the late stages of peptidoglycan synthesis. Their natural substrate is the C-terminal D-Ala-D-Ala dipeptide of the stem pentapeptide necessary to cross-link the glycan chains of the peptidoglycan. 3 A series of compounds, mainly containing variations on the theme of the β-lactam ring, have proven their efficacy as PBP inhibitors. For over 60 years, penicillins, cephalosporins, monobactams, and carbapenems have been used to combat all types of bacterial infections and continuously developed in response to the progressive bacterial resistance to β-lactam antibiotics. Recent research has intensified the investigation of non-β-lactam inhibitors of PBPs, e.g., lactivicin, a bicyclic molecule with a γ-lactam/ γ-lactone ring structure, 4,5 and shown that boronic acids represent potential inhibitors of PBPs. 6À8 It has been known for a long time that serine amidohydrolases are inhibited by boronic acids, and structures of complexes between boronic acids and trypsin, chymotrypsin, subtilisin, elastase, R-lytic protease, serine β-lactamases, prolyl tripeptidyl aminopeptidase, and hormone-processing protease have been described extensively. 9À16 Most structures with boronic acids show the boron atom in a tetrahedral conformation, forming a covalent adduct with the catalytic serine, occupying 50 the oxyanion hole, and underlining the analogy with the transi-51 tion state of the catalytic process. Escherichia coli PBP5 was the first PBP for which the crystallo-53 graphic structure of a boronic acid complex was described. This 54 structure has helped decipher the deacylation mechanism of 55 penicillin-binding proteins. More recently, we described the struc-56 ture of the DD-peptidase of Actinomadurax sp. R39 (R39) with an 57 ethylboronic acid bearing the side chain of diaminopimelic acid, a 58 characteristic amino acid of the peptidoglycan, providing a view of a 59 transition state close to the one that is expected with the natural 60 substrate of PBPs. 6 61 Although almost all of these structures reveal the boron 62 involved in a single dative covalent bond with the catalytic serine, 63 other covalent complexes are possible between serine proteases 64 and boronic acids. A dicovalent complex was first observed with 65 γ-chymotrypsin and D-p-chlorophenyl-or D-1-naphthylboronic 66 acids. 15 Both compounds linked to Ser195Oγ and His57Nε2, 67 two residues of the catalytic triad of γ-chymotrypsin. Likewise, 68 dicovalent complexes with borate and benzylboronate linked to

Palladium catalysed, aryl boronic acid homocoupling, is explored as a fluorescence sensing regime for saccharides. The catalytic formation rate of fluorescent bi-aryls, under control of a palladium catalyst, is modulated by the presence of saccharides. The nature of the aryl group, rate of biaryl formation and limits of detection are investigated.

B oronic acids can interact with Lewis bases to generate boronate anions, and they can also bind with diol units to form cyclic boronate esters. Boronic acid based receptor designs originated when Lorand and Edwards used the pH drop observed upon the addition of saccharides to boronic acids to determine their association constants. The inherent acidity of the boronic acid is enhanced when 1,2-, 1,3-, or 1,4-diols react with boronic acids to form cyclic boronic esters (5, 6, or 7 membered rings) in aqueous media, and these interactions form the cornerstone of diol-based receptors used in the construction of sensors and separation systems. In addition, the recognition of saccharides through boronic acid complex (or boronic ester) formation often relies on an interaction between a Lewis acidic boronic acid and a Lewis base (proximal tertiary amine or anion). These properties of boronic acids have led to them being exploited in sensing and separation systems for anions (Lewis bases) and saccharides (diols). The fast and stable bond formation between boronic acids and diols to form boronate esters can serve as the basis for forming reversible molecular assemblies. In spite of the stability of the boronate esters' covalent BÀO bonds, their formation is reversible under certain conditions or under the action of certain external stimuli. The reversibility of boronate ester formation and Lewis acidÀbase interactions has also resulted in the development and use of boronic acids within multicomponent systems. The dynamic covalent functionality of boronic acids with structuredirecting potential has led researchers to develop a variety of self-organizing systems including macrocycles, cages, capsules, and polymers. This Account gives an overview of research published about boronic acids over the last 5 years. We hope that this Account will inspire others to continue the work on boronic acids and reversible covalent chemistry.

A branched peptide containing multiple boronic acids was found to bind RRE IIB selectively and inhibit HIV-1 p24 capsid production in a dose-dependent manner. Structure-activity relationship studies revealed that branching in the peptide is crucial for the low micromolar binding towards RRE IIB, and that the peptide demonstrates selectivity towards RRE IIB in the presence of tRNA. Footprinting studies suggest a binding site on the upper stem and internal loop region of the RNA, which induces enzymatic cleavage of the internal loops of RRE IIB upon binding.

Gold nanoparticles (NPs) are essential components in the design of various functional systems of nanometer dimensions. Their properties are determined by their size and the chemical composition of their capping layer. We have recently presented a scheme for controlled modification of Au NP capping layers by reversible binding to a polymeric solid support via boronic acid chemistry. Octanethiol-stabilized Au NPs were bound reversibly to a polymeric resin derivatized with boronic acid groups. Specially synthesized bifunctional linker molecules carrying a diol on one end and a thiol on the other were bound to the boronic moieties on the resin via the diol group, enabling attachment of Au NPs to the linkerloaded resin through the thiol moiety of the linkers. The resin-bound NPs could be released back to solution by cleaving the boronate ester between the resin and the linker, leaving one (or a few) linker molecule(s) on the NPs. The released NPs retained their properties (optical, solubility) and could be rebound to boronic resins through the linker molecules on their surface. This process of reversible NP binding to a polymeric solid support is studied here in detail. Several boronic-modified resins and linker molecules were prepared and investigated. The chemical conditions for cleavage of the boronate ester were found to be different for NP-free and NP-loaded resins, varying with the type of diol on the linker molecules. Reversible NP binding to high-surface-area solid supports may be useful for preparative reactions on NPs, including controlled NP modification, design of synthetic schemes for modification of NPs under protected conditions, and prevention of NP-NP interactions during chemical manipulation.

Fundamental information on the reactivities of boronic acids toward catechols in aqueous solution is required in all the fields dealing with boronic acid. However, comprehensive studies on reactivity are often hindered by so-called "proton ambiguity," which makes it impossible for the rate constants of boronic acid and boronate ion to be determined separately. Herein, we set up two reaction systems without proton ambiguity: (1) Alizarin Red S and (2) Tiron with several boronic acids (RB(OH) 2 ) with different pK a s and performed kinetic and equilibrium studies on the reaction systems. It was shown that the logarithms of the rate constants of RB(OH) 2 and its conjugate boronate ion (RB(OH) 3 -) decreased and increased linearly, respectively, with increasing pK a of RB(OH) 2 for both systems. Consequently, the reactivities of RB(OH) 2 and RB(OH) 3 -were reversed at high RB(OH) 2 pK a . It was also shown that the bulky o - substituents of phenylboronic acids retarded the backward reactions, resulting in enhancement of the formation constants of boronic acid-catechol esters.

Many oxidative stress related diseases and adverse health conditions have been associated with the negative effects of hydrogen peroxide and other similar reactive oxygen species in human body. Therefore, increasing attention has been attracted to the detection and monitoring of hydrogen peroxide in living organisms and food items. In this work, a simple, inexpensive colorimetric method for the quantitative determination of hydrogen peroxide in aqueous sample is described. This method utilizes the de-protection of aryl boronic acid to yield a strongly colored water-soluble dye, which is capable of absorbing and emitting in the red region of the spectrum. The mechanism is faster in alkaline condition and utilizes the intramolecular charge transfer between strong phenolate donor and TCF acceptor, thus allowing a naked eye detection of hydrogen peroxide within seconds. The method is unaffected by the presence of various salts, metal ions, and other interfering species, and it can provide a limit of detection as low as ~1 ppm in aqueous samples. This unique way of generating a fluorogenic donor-acceptor pair holds a potential of this dye and other related derivatives for understanding the role of hydrogen peroxide in physiology and pathology.

In this presented paper, boronic acid incorporated poly(HEMA) based nanoparticles were synthesized for RNA adsorption. For this purposes, poly(HEMA) nanoparticles were synthesized by using surfactant free emulsion polymerization technique. Then, nanoparticles were modified with 3-(2-imidazoline-1-yl)propyl(triethoxysilane) (IMEO) and functionalized with phenylboronic acid (PBA). Prepared nanoparticles were characterized with SEM, FTIR and Zeta-size. Optimum RNA adsorption conditions were investigated with different pH's, temperature and initial RNA concentrations in order to determine the maximum RNA adsorption onto poly(HEMA)-IMEO-PBA nanoparticles. It was also studied that, synthesized nanoparticles could be used for the successive 5 reuses and adsorption capacity of the nanoparticles decreased only about 5 % at the end of the 5 cycles.

AbstractÐBoronic acids bind with compounds containing diol moieties with high af®nity through reversible boronate formation. However, the conditions that foster tight binding between the diol and the boronic acid are not well understood. Also, due to the multiple ionic states of both the boronic acid and boronate ester, the equilibrium constants reported in the literature have not always been strictly de®ned, and therefore there is a lack of `comparability' between the reported values. To address these issues, we have developed a method for examining boronate ester stability using the ¯uorescent reporter Alizarin Red S. We have used this system to determine the binding constants of a series of diols, and as a basis from which to derive a number of relationships that correlate the various equilibrium constants in the literature.

Boronic acids and their esters are highly considered compounds for the design of new drugs and drug delivery devices, particularly as boron-carriers suitable for neutron capture therapy. However, these compounds are only marginally stable in water. Hydrolysis of some phenylboronic pinacol esters is described here. The kinetics is dependent on the substituents in the aromatic ring. Also the pH strongly influences the rate of the reaction, which is considerably accelerated at physiological pH. Therefore, care must be taken when considering these boronic pinacol esters for pharmacological purposes.

Theoretical parameters for 1 amino 2-(3,4-dihydroxyphenyl) boronic acid in AHPEBA were investigated using density functional theory (DFT), and STO-3G basis set. Quantum chemical calculations were done on the link between inhibitor molecular structure, chemical reactivity, stability, and inhibition performance. In addition, we investigate the theoretical foundations of AHPEBA by looking at properties and characteristics such as the Highest Occupied Molecular Orbital (HOMO), the Lowest Unoccupied Molecular Orbital (LUMO), the Band Gap (BG), the Density of States (DOS), the Ultraviolet (UV) properties, and the Natural Bond Orbital (NBO) evaluations. Also, we use the reduced density gradient (RDG) method to explore non-covalent interactions (NCI). The fact that the BG was measured to be -5.85043 eV lent credence to the hypothesis that the molecule had a high level of chemical stability and a low level of chemical reactivity. According to molecular hardness and softness, electronegativity, and chemical potential, the molecule C8H12BNO4 has a high degree of chemical stability, and a low degree of reactivity. This is the first theoretical study of the AHPEBA compound.

A novel superabsorbent hydrogel composite based on alginate have been prepared via graft copolymerization of acrylamide(AAm) and 2-acrylamideeo-2-methylpropanesulfonic acid (AMPS) in the presence of kaolin powder using methylenebisacrylamide (MBA) as a crosslinking agent and ammonium persulfate (APS) as an initiator. Evidence of grafting and kaolin interaction was obtained by comparison of FTIR, SEM and TGA spectra of initial substrates and superabsorbent composite.

Biologically relevant N-arylisoindolinones efficiently underwent arylation reactions under ruthenium catalysis via C-H bond functionalization. The reactions exclusively led to mono-arylated products and only ortho selectivity was observed in the aromatic ring connected to the nitrogen atom. Interestingly, no C-H bond functionalization was observed in the other benzene ring being in ortho position with respect to the carbonyl group. This ruthenium-catalyzed reaction displayed a high functional group tolerance, and it employed readily available and benchmark stable boronic acid and potassium aryltrifluoroborate derivatives as coupling partners. An appealing late-stage functionalization of indoprofen applying this methodology is showcased.