Structure of 4-[4-(Dimethylamino)-Phenylazo] Benzeneboronic Acid and Its Cyclic Esters with D-Glucose: A Computational Study

We present results from a computational study of 4-[4-(dimethylamino)-phenylazo] benzene boronic acid (DABBA) (the 4'-boronic acid isomer of the aminoazobenzene dye N,N-dimethylaminoazobenzene) and its associated anion, as well as, several cyclic esters formed from these azoborates and various conformers of D-glucose. Azo dyes that also contain one or more boronic acid functional groups are of practical importance in the development of chemical sensors for saccharide recognition because of their ability to induce a visible color change upon binding. The lowest-energy DABBA:D-glucose esters found in this investigation consistently involved at least one of the exocyclic hydroxymethyl groups on the D-glucose moiety rather than vicinal cis or trans diol arrangements of hydroxyl groups on the ring.     

One saccharide sensor based on the complex of the boronic acid and the monosaccharide using electrochemical impedance spectroscopy

A novel saccharide sensor based on the covalent interaction between the boronic acid and saccharides was developed. Poly (aminophenylboronic acid) (PABA) was prepared by electropolymerizing 3-aminophenylboronic acid on gold electrode surface in acidic solution. The boronic acid group of the PABA film can form covalent-bond with different saccharides, which can change the dielectric characteristics of the PABA film, and the change of the dielectric characteristic was saccharides concentration dependent. Four kinds of saccharides could be detected by using electrochemical impedance spectroscopy. Good linear relationship and high sensitivity were obtained by this method.     

Saccharide Sensing Based on Saccharide‐Induced Conformational Changes in Fluorescent Boronic Acid Polymers

Summary: A novel fluorometric saccharide detection strategy has been established by utilizing saccharide‐induced conformational changes in copolymers containing boronic acid and fluorescent units. The polymer chain changes its conformation due to an alteration of the charge state induced by binding with saccharides. The conformational changes are conveniently detected by monitoring excimer to monomer intensity ratio in the fluorescence spectra. Thus, the present strategy would be a promising way for the creation of highly selective and sensitive saccharide‐sensing systems.

Saccharide‐induced conformational change in copolymers containing boronic acid units.     

Colorimetric and bare-eye detection of alkaline earth metal ions based on the aggregation of silver nanoparticles functionalized with thioglycolic acid

We describe a simple and rapid method for colorimetric and bare-eye detection of the alkaline earth metal ions Mg(II), Ca(II), Sr(II) and Ba(II) based on the use of silver nanoparticles (AgNPs) functionalized with thioglycolic acid (TGA). The TGA ligand was self-assembled onto the AgNPs to form a probe that undergoes a color change from yellow to orange or red on exposure to the alkaline earth ions. It is presumed that the color change is a result of the aggregation of the AgNPs caused by the interaction of the bivalent ions with the carboxy groups on the AgNPs. The color change can be used for bare-eye and colorimetric determination of the alkaline earth metal ions, for example to rapidly determine water hardness.

Modulation of color changing paths for flavylium salts by solvent and concentration

The modulations of the color changing paths for flavylium salt (2-phenylbenzopyrilium, abbreviated as FV) by solvent and their concentrations have been studied by observing changes in the UV-Vis absorption spectra. The feature of the spectral changes varies with the solvent and solution FV concentration. The color of the solutions in ethanol at high concentration changed from yellow to red via green. It has been proposed that the yellow, green, and red species of FV are a monomer, a monomer with charge-transfer character, and a dimer and/or aggregate of FV, respectively. The spectral changes showed different behaviors in different solvents. In ethanol solution with a low concentration, a chalcone was generated by nucleophilic addition. The PM3 calculation revealed a new reaction path where the green FV is converted to a chalcone in propylene glycol. The color changing paths for FVs were able to be modulated in different solvents and by their concentration change. The previous proposed scheme well explained the experimental results in various solvents.     

An ultrasensitive method of real time pH monitoring with complementary metal oxide semiconductor image sensor

CMOS sensors are becoming a powerful tool in the biological and chemical field. In this work, we introduce a new approach on quantifying various pH solutions with a CMOS image sensor. The CMOS image sensor based pH measurement produces high-accuracy analysis, making it a truly portable and user friendly system. pH indicator blended hydrogel matrix was fabricated as a thin film to the accurate color development. A distinct color change of red, green and blue (RGB) develops in the hydrogel film by applying various pH solutions (pH 1–14). The semi-quantitative pH evolution was acquired by visual read out. Further, CMOS image sensor absorbs the RGB color intensity of the film and hue value converted into digital numbers with the aid of an analog-to-digital converter (ADC) to determine the pH ranges of solutions. Chromaticity diagram and Euclidean distance represent the RGB color space and differentiation of pH ranges, respectively. This technique is applicable to sense the various toxic chemicals and chemical vapors by situ sensing. Ultimately, the entire approach can be integrated into smartphone and operable with the user friendly manner.     

新型含苯硼酸和喹啉的囊泡荧光多糖传感器的制备

利用合成的含有识别基团苯硼酸和荧光读出基团喹啉的新型双亲化合物对硼酸苯甲基-8-十六烷氧基溴化喹啉(BHQB)在水中自组织成囊泡,囊泡的相变温度为52.4℃;当向囊泡体系加糖时,BHQB囊泡中的喹啉生色基在508nm的荧光峰强度急剧减弱,425nm处荧光逐渐增强.荧光强度变化可能归于所形成的硼酸酯改变了双亲化合物中硼原子的杂化轨道形式,进一步引起了整个分子内部的电子云排布所致.BHQB囊泡与糖的相互作用而导致体系荧光强度变化,并且这种变化的幅度与加入糖的种类和量均有关.因此体系有可能应用于检测生物物质如糖的化学传感器.     

茜素红S-硼酸体系对单糖的双光谱识别

利用硼酸与茜素红S和糖中的邻二羟基可逆结合的特点,以硼酸为中介运用竞争结合作用机理构建单糖分析法.在pH7.4的KH2PO4-NaOH缓冲溶液中,茜素红S作为指示剂与硼酸结合生成ARS-BA配合物,其结合常数为5.09×102L/mol.糖与指示剂ARS竞争结合硼酸使指示剂游离出来,产生明显的颜色变化,据此建立糖的识别方法.考察了D-葡萄糖、D-山梨醇、D-半乳糖、D-甘露糖、D-果糖、D-阿拉伯糖和L-阿拉伯糖对上述ARS-BA体系光谱的影响.结果显示:该体系对D-山梨醇和D-果糖有较好的光谱响应,其光谱变化灵敏度依D-山梨醇＞D-果糖＞D-阿拉伯糖～D-半乳糖＞D-葡萄糖＞D-甘露糖＞L-阿拉伯糖之序.     

A temperature and pH double sensitive cholesteric polymer film from a photopolymerizable chiral hydrogen-bonded assembly

In this study, a novel H-bonded cholesteric polymer film responding to temperature and pH by changing the reflection color was fabricated. The H-bonded cholesteric polymer film was achieved by UV-photopolymerizing a cholesteric liquid crystal (Ch-LC) monomers mixture containing a photopolymerizable chiral H-bonded assembly (PCHA). The cholesteric polymer film based on PCHA can be thermally switched to reflect red color from the initial green/yellow color as temperature is increased, which is due to a change in helical pitch induced by the weakening of H-bonded interaction in the polymer film. Additionally, the selective reflection band (SRB) of the cholesteric polymer film in solution with pH > 7 showed an obvious red shift with increasing pH values. While the SRB of the cholesteric polymer film in solutions with pH = 7 and pH < 7 hardly changed. This pH sensitivity in solutions with pH > 7 could be explained by the breakage of H-bonds in the cholesteric polymer film and the structure changes induced by―OH and―K + ions in the alkaline solution. In contrast, it couldn’t happen in the neutral and acidic solutions. The cholesteric polymer film in this study can be used as optical/photonic papers, optical sensors and LCs displays, etc.     

Synthesis of new bis-benzylidene-hydrazides as a sensitive chromogenic sensor for naked-eye detection of CN¯ and AcO¯ ions

Some new bis-benzylidene-hydrazides were synthesized via a condensation reaction of the corresponding azo dyes with adipic acid dihydrazide. All compounds because of the three possible stereoisomers showed four sets of signals in NMR. The anion recognition studies exhibited that the nitro bis-benzylidene-hydrazide derivative acts as a highly sensitive and selective chromogenic sensor for naked-eye detection of CN¯ and AcO¯ ions, with a distinct color change from yellow to blue and yellow to purple, respectively. The limit of detection (LOD) was found for 1d toward CN¯ to be 1.1?μM. The result of the Job's plot indicated stoichiometry of binding between chemosensor and anions is found to be 1:2.     

Preparation of highly selective solid-phase extractants for Cibacron reactive dyes using molecularly imprinted polymers

Selective polymeric extractants were prepared for preconcentration of Cibacron reactive red dye, a dye that is often applied with Cibacron reactive blue and Cibacron reactive yellow for dyeing of fabrics. The best extractant was fabricated (in chloroform) using methacrylic acid (as monomer), ethylene glycol dimethacrylate (as crosslinker), AIBN (as initiator for polymerization), and red dye as template molecule, with a molar stoichiometric ratio of 8.0:40.0:2.5:0.63, respectively. The structure of the molecularly imprinted polymer (MIP) was robust, and resisted dissolution up to 260 °C. Compared with the un-imprinted polymer, the imprinted product has a large specific surface area which improved its adsorption capacity. The effect of imprinting was obvious from the adsorption capacity measured at pH 4 for red dye (the imprinted molecule), which was increased from 24.0 to 79.3 mg g⁻¹ after imprinting. Equilibrium adsorption studies revealed that the dye-imprinted-polymer enables efficient extraction of red dye even in the presence of blue and yellow dyes which have similar chemical natures to the red dye. The selectivity coefficients S _{red dye/dye}, were 13.9 and 17.1 relative to the yellow and blue dyes, respectively. The MIP was found to be effective for red dye preconcentration, with a preconcentration factor of 100, from tap water and treated textile wastewater. The factors affecting extraction of red dye by the MIP were studied and optimized. Under the optimized extraction conditions, red dye was selectively quantified in the presence of other competing dyes at a concentration of 20 μg L⁻¹ from different water systems with satisfactory recoveries (91–95%) and RSD values (∼5.0%).     

Photophysical properties and photochemical rearrangement of single crystal salicylideneaniline in solution

Salicylideneaniline originally crystallized from a solution has lemon yellow color. Irradiation with near ultraviolet causes the color change from yellow to red. The red state changes spontaneously back to yellow in 2ms. This change is accelerated by visible light. Kinetic data are reported in the temperature range between 10 and 60 degrees C, for the dark fading reactions of the colored isomers formed by the near ultraviolet irradiation. Observed the decay kinetics was first order reactions. Activation energies and entropies of activation are reported for ethanol. The observation of T-T absorption and emission were complicated due to the colored isomer formation during the optical pumping.     

A Three‐Component Assembly Promoted by Boronic Acids Delivers a Modular Fluorophore Platform (BASHY Dyes)

The modular assembly of boronic acids with Schiff‐base ligands enabled the construction of innovative fluorescent dyes [boronic acid salicylidenehydrazone (BASHY)] with suitable structural and photophysical properties for live cell bioimaging applications. This reaction enabled the straightforward synthesis (yields up to 99 %) of structurally diverse and photostable dyes that exhibit a polarity‐sensitive green‐to‐yellow emission with high quantum yields of up to 0.6 in nonpolar environments. These dyes displayed a high brightness (up to 54 000 m ^?1 cm^?1). The promising structural and fluorescence properties of BASHY dyes fostered the preparation of non‐cytotoxic, stable, and highly fluorescent poly(lactide‐co‐glycolide) nanoparticles that were effectively internalized by dendritic cells. The dyes were also shown to selectively stain lipid droplets in HeLa cells, without inducing any appreciable cytotoxicity or competing plasma membrane labeling; this confirmed their potential as fluorescent stains.     

Self‐Assembly and Dispersion of Chromogenic Molecules: A Versatile and General Approach for Self‐Assessing Polymers

Summary: Self‐assessing polymer blends based on poly(ethylene terephthalate glycol) or linear low‐density polyethylene and small amounts (0.5–2% w/w) of chromogenic sensor dyes are prepared and investigated. The cyano‐substituted oligo(p‐phenylene vinylene) dyes employed in the study exhibit pronounced optical absorption changes upon self‐assembly, because of charge‐transfer interactions or conformation changes. The extent of dye aggregation (and therewith the optical absorption characteristics) in these blends is significantly influenced by exposure to external stimuli. Subjecting appropriately processed samples to either temperatures above their glass transition or mechanical deformation can significantly change the extent of aggregation, which in turn leads to a color change.

Mechano‐optical response of a 1.0% w/w LLDPE/C18‐RG blend film. Pristine films are orange due to aggregated dye molecules. Deformation leads to dispersion of the dye and irreversibly changes the color to yellow.     

Bifunctional maleimide dyes as selective anion sensors

A class of disubstituted maleimide dyes with two symmetrical NH binding sites was found to exhibit distinct color change and fluorescence quenching effect for fluoride, cyanide, and dihydrogen phosphate anions. The intense red emission displayed apparent solvatochromic shift, indicating a strong charge-transfer character. The interactions between the dyes and anions were variable depending on the amine substituents at C(3,4) of the maleimides. For the dyes with two pyrrolyl receptor sites, the NH protons were deprotonated by more basic anions such as fluoride or cyanide. For those with two indolyl receptor sites, formation of a chelate with H₂PO₄⁻ through hydrogen bonds played a major role.     

Fluororeactands for the Detection of Saccharides Based on Hemicyanine Dyes with a Boronic Acid Receptor

Three hemicyanine dyes with boronic acid receptor functions have been synthesized in a two step procedure. These dyes are capable of forming a covalent bond between their boronic acid moiety and the diol moiety of saccharides which causes fluorescence to change. In detail, the indicator dyes exhibit absorbance maxima at around 460 nm and emission at around 600 nm, show increases in fluorescence upon exposure to saccharides and can be used in aqueous solution at physiological pH.     

Buildup of gold nanoparticle multilayer thin films based on the covalent-bonding interaction between boronic acids and polyols

A novel method for the fabrication of gold nanoparticle multilayer films based on the covalent-bonding interaction between boronic acid and polyols, poly(vinyl alcohol) (PVA), was developed. The multilayer buildup was monitored by UV-vis absorbance spectroscopy, which showed a linear increase of the film absorbance with the number of adsorbed Au layers and indicated the stepwise and uniform assembling process. The atomic force microscopy (AFM) image showed that a compact gold multilayer thin film was successfully assembled. The residual boronic acid group on the surface of thin film could incorporate glycosylated-protein horseradish peroxidase (HRP), and good catalytic activity for H2O2 could be observed.     

Multicolor Fluorescence Writing Based on Host–Guest Interactions and Force‐Induced Fluorescence‐Color Memory

A new strategy is reported for multicolor fluorescence writing on thin solid films with mechanical forces. This concept is illustrated by the use of a green‐fluorescent pentiptycene derivative 1 , which forms variably colored fluorescent exciplexes: a change from yellow to red was observed with anilines, and fluorescence quenching (a change to black) occurred in the presence of benzoquinone. Mechanical forces, such as grinding and shearing, induced a crystalline‐to‐amorphous phase transition in both the pristine and guest‐adsorbed solids that led to a change in the fluorescence color (mechanofluorochromism) and a memory of the resulting color. Fluorescence drawings of five or more colors were created on glass or paper and could be readily erased by exposure to air and dichloromethane fumes. The structural and mechanistic aspects of the observations are also discussed.     

An Efficient and Simple Reaction: Solvent-Free Preparation of Rosolic Acid Under Microwave Irradiation

1 Introduction Rosolic acid, also called as resinous acid, is a trihydroxyphenyl methane dye mainly used as an oxidation resistant indicator in acid-base titration with sharp color change depending on the pH, from 5.0（yellow） to 6.8（pink）. It is also used as an initial reactant in the syntheses of 4,4＇,4＂-tris（acyloxy）trityl chloride and its bromide for protection of primary hydroxyl groups, and a monomer in polyreaction to prepare color polymer fiber as pH probe.     

Sol–gel derived dye-bridged hybrid materials for white luminescence

Novel yellow and blue emissive dyes have been synthesized using 2,5-diamino-3,6-dicyanopyrazine and various alkoxysilanes and they are covalently bridged to cycloaliphatic epoxy functional oligosiloxane via non-hydrolytic sol–gel reaction. Dye-bridged hybrid materials (DBH) are fabricated by thermal curing the dye-bridged oligosiloxane. Structure and formation of dyes and siloxane network is studied using analysis method. Four components of red, yellow, green and blue emitting DBH cover entire visible range and white luminescence with high color rendering index is realized by controlling their combinations. We have ensured superior thermal stability DBH at 120 °C for 200 h caused by covalently bridged structure and robust siloxane matrix.