A unique quinolineboronic acid-based supramolecular structure that relies on double intermolecular B–N bonds for self-assembly in solid state and in solution

NMR Quantification of Hydrogen-Bond-Activating Effects for Organocatalysts including Boronic Acids

The hydrogen-bonding activation for 66 organocatalysts has been quantified using a ³¹P NMR binding experiment with triethylphosphine oxide (TEPO). Diverse structural classes, including phenols, diols, silanols, carboxylic acids, boronic acids, and phosphoric acids, were examined with a variety of steric and electronic modifications to understand how the structure and secondary effects contribute to hydrogen-bonding ability and catalysis. Hammett plots demonstrate high correlation for the Δδ ³¹P NMR shift to Hammett parameters, establishing the ability of TEPO binding to predict electronic trends. Upon correlation to catalytic activity in a Friedel-Crafts addition reaction, data demonstrate that ³¹P NMR shifts correlate to catalytic activity better than p K_a values. Boronic acids were investigated, and ³¹P NMR binding experiments predicted strong hydrogen-bonding ability, for which catalytic activity was confirmed, resulting in the greatest rate enhancement observed in the Friedel-Crafts addition of all organocatalysts studied. A detailed investigation supports that boronic acid activation proceeds through hydrogen-bonding interactions and not coordination with the Lewis acidic boron center. Using ³¹P NMR spectroscopy offers a simple and rapid tool to quantify and predict hydrogen-bonding abilities for the design and applications of new organocatalysts and supramolecular synthons.

Experimental and theoretical studies of molecular complexes of theophylline with some phenylboronic acids

Molecular complexes of active pharmaceutical ingredient theophylline with p-substituted-chloro, -bromo, -iodo and -hydroxyphenylboronic acids as well as 1,4-phenylene-bis-boronic acid have been reported.

Hydrolysis of 8-(pinacolboranyl)quinoline: where is the 8-quinolylboronic acid?

The compound 8-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-quinoline was prepared and found to hydrolyze rapidly in air; however, the expected product (quinolin-8-yl)boronic acid was not observed. Instead, the (quinolinium-8-yl)trihydroxyborate zwitterion or an anhydride were observed depending on the conditions of hydrolysis. The two products are related to one another in the degree of hydration, and the two forms could be interconverted. Both hydrolysis products were structurally characterized. Additionally, a commercial sample of ‘8-quinolylboronic acid’ was actually found to be the anhydride. The results call into question whether monomeric (quinolin-8-yl)boronic acid can actually be isolated in the neutral Lewis base-free form.

Supramolecular assembly of crosslinkable monomers for degradable and fluorescent polymer nanoparticles

Intermolecular B-N coordination has been recognized as a promising driving force for molecular self-organization. However, direct utilization of this intermolecular interaction as building bridge for the supramolecular self-assembly of chemical functionalities to form nano-sized architectures remains a daunting challenge. Here, we outline a multiple intermolecular B-N coordination based supramolecular system, where small boronate molecules can be brought together in solution to form nanoparticles with controllable sizes and morphologies. We not only demonstrate the intrinsic switchable fluorescence and the stimuli-responsive capabilities of the designed boronate molecule, but also show that the stabilized or surface functionalized nanoparticles are degradable in response to pH and D-glucose and able to retain the fluorescence features of the boronate molecule. Additionally, the degraded nanoparticles can repair themselves through the reformation of B-N coordination.

Synthesis of 8-arylquinolines via one-pot Pd-catalyzed borylation of quinoline-8-yl halides and subsequent Suzuki-Miyaura coupling

A one-pot process has been developed for the synthesis of 8-arylquinolines via Pd-catalyzed borylation of quinoline-8-yl halides and subsequent Suzuki-Miyaura coupling with aryl halides using n-BuPAd(2) as ligand. Yields of up to 98% were obtained.

Determination of trace alkaline phosphatase by affinity adsorption solid substrate room temperature phosphorimetry based on wheat germ agglutinin labeled with 8-quinolineboronic acid phosphorescent molecular switch and prediction of diseases

The 8-quinolineboronic acid phosphorescent molecular switch (abbreviated as PMS-8-QBA. Thereinto, 8-QBA is 8-quinolineboronic acid, and PMS is phosphorescent molecular switch) was found for the first time. PMS-8-QBA, which was in the "off" state, could only emit weak room temperature phosphorescence (RTP) on the acetyl cellulose membrane (ACM). However, PMS-8-QBA turned "on" automatically for its changed structure, causing that the RTP of 8-QBA in the system increased, after PMS-8-QBA-WGA (WGA is wheat germ agglutinin) was formed by reaction between -OH of PMS-8-QBA and -COOH of WGA. More interesting is that the -NH(2) of PMS-8-QBA-WGA could react with the -COOH of alkaline phosphatase (AP) to form the affinity adsorption (AA) product WGA-AP-WGA-8-QBA-PMS (containing -NH-CO- bond), which caused RTP of the system to greatly increase. Thus, affinity adsorption solid substrate room temperature phosphorimetry using PMS-8-QBA as labelling reagent (PMS-8-QBA-AA-SSRTP) for the determination of trace AP was established. The method had many advantages, such as high sensitivity (the detection limit (LD) was 2.5zgspot(-1). For sample volume of 0.40mulspot(-1), corresponding concentration was 6.2x10(-18)gml(-1)), good selectivity (the allowed concentration of coexisting material was higher, when the relative error was +/-5%), high accuracy (applied to detection of AP content in serum samples, the result was coincided with those obtained by enzyme-linked immunoassay), which was suitable for the detection of trace AP content in serum samples and the forecast of human diseases. Meanwhile, the mechanism of PMS-8-QBA-AASSRTP was discussed. The new field of analytical application and clinic diagnosis technique of molecule switch are exploited, based on the phosphorescence characteristic of PMS-8-QBA, the AA reaction between WGA and AP, as well as the relation between AP content and human diseases. The research results promote the development and interpenetrate among molecule switch technique, lectin science and SSRTP.

3-Amino-phenyl-boronic acid monohydrate

In the title compound, C(6)H(8)BNO(2)·H(2)O, the almost planar boronic acid mol-ecules (r.m.s. deviation = 0.044 Å) form inversion dimers, linked by pairs of O-H⋯O hydrogen bonds. The water mol-ecules link these dimers into [100] chains by way of O-H⋯O hydrogen bonds, and N-H⋯O links generate (100) sheets.

Bis[3-(dihydroxy-boryl)anilinium] sulfate

In the title compound, 2C₆H₉BNO₂⁺·SO₄²⁻, the dihydroxy­boryl group of one of the two independent boronic acid mol­ecules participates in (B)O—H⋯O_B and N—H⋯O_B hydrogen bonds, while the second is involved mainly in the formation of the charge-assisted heterodimeric synthon –B(OH)₂⋯⁻O₂SO₂⁻. These aggregates are further connected through N—H⋯O_sulfate inter­actions, forming a complex three-dimensional hydrogen-bonded network.

Carbohydrate biomarkers for future disease detection and treatment

Carbohydrates are considered as one of the most important classes of biomarkers for cell types, disease states, protein functions, and developmental states. Carbohydrate "binders" that can specifically recognize a carbohydrate biomarker can be used for developing novel types of site specific delivery methods and imaging agents. In this review, we present selected examples of important carbohydrate biomarkers and how they can be targeted for the development of therapeutic and diagnostic agents. Examples are arranged based on disease categories including (1) infectious diseases, (2) cancer, (3) inflammation and immune responses, (4) signal transduction, (5) stem cell transformation, (6) embryo development, and (7) cardiovascular diseases, though some issues cross therapeutic boundaries.

The development of a selective cyclin-dependent kinase inhibitor that shows antitumor activity

Normal progression through the cell cycle requires the sequential action of cyclin-dependent kinases CDK1, CDK2, CDK4, and CDK6. Direct or indirect deregulation of CDK activity is a feature of almost all cancers and has led to the development of CDK inhibitors as anticancer agents. The CDK-activating kinase (CAK) plays a critical role in regulating cell cycle by mediating the activating phosphorylation of CDK1, CDK2, CDK4, and CDK6. As such, CDK7, which also regulates transcription as part of the TFIIH basal transcription factor, is an attractive target for the development of anticancer drugs. Computer modeling of the CDK7 structure was used to design potential potent CDK7 inhibitors. Here, we show that a pyrazolo[1,5-a]pyrimidine-derived compound, BS-181, inhibited CAK activity with an IC(50) of 21 nmol/L. Testing of other CDKs as well as another 69 kinases showed that BS-181 only inhibited CDK2 at concentrations lower than 1 micromol/L, with CDK2 being inhibited 35-fold less potently (IC(50) 880 nmol/L) than CDK7. In MCF-7 cells, BS-181 inhibited the phosphorylation of CDK7 substrates, promoted cell cycle arrest and apoptosis to inhibit the growth of cancer cell lines, and showed antitumor effects in vivo. The drug was stable in vivo with a plasma elimination half-life in mice of 405 minutes after i.p. administration of 10 mg/kg. The same dose of drug inhibited the growth of MCF-7 human xenografts in nude mice. BS-181 therefore provides the first example of a potent and selective CDK7 inhibitor with potential as an anticancer agent.

Synthesis, characterization, and antifungal activity of boron-containing thiosemicarbazones

Addition of thiosemicarbazide, 4-allylthiosemicarbazide, and 4-phenylthiosemicarbazide to (formylphenyl)boronic acids affords a series of thiosemicarbazones containing boronic acids. Addition of 2-formylphenylboronic acid to the thiosemicarbazides gave the corresponding cyclic 2,3,1-benzodiazaborines. All new compounds have been investigated for potential antifungal activity.