Pd(II)-Catalyzed Benzimidazole-Assisted Annulation of 3-(1H-Benzo[d]imidazol-2-yl)-2H-chromen-2-one: Access to Imidazo[1,2-a]chromeno[3,4-c]pyridine

Palladium-catalyzed [4+2] oxidative annulation of coumarin-benzimidazoles with olefins for the synthesis of polycyclic aromatic hydrocarbons have been achieved. This synthetic protocol gives access to a wide range of structurally distinct imidazo[1,2-a]chromeno[3,4-c]pyridines in moderate to good yield with wide functional group tolerance. Further, photophysical properties of annulated scaffolds have been examined, which discloses their interesting solvatochromic emission behaviors.     

CO2 Hydroboration: Impact of the Boryl Moieties on the Reactivity of Four Bis(boryl)acetal Compounds toward 2,6-Diisopropylaniline

The hydroboration of CO₂ into bis(boryl)acetal (BBA) compounds is an important transformation, since it enabled to selectively reduce CO₂ by 4e^- and to subsequently use the BBA compounds as C₁ and C_n sources. However, the influence of the nature of the boryl moieties on the reactivity of BBA compounds has not been evaluated so far. In the present study, four BBA compounds – including two new ones – were reacted with 2,6-diisopropylaniline to afford the expected imine. Significant differences in the rate of the reaction from minutes to weeks have been observed depending on the BBA used, showing the importance of the nature of the boryl moieties. Theoretical investigations enabled to propose a mechanism involving the addition of the aniline to the BBA as the rate-determining step and to determine that the steric hindrance of the BBA compounds is the main factor driving the rate of this condensation reaction.     

两亲性D-π-A型有机染料在染料敏化太阳能电池中的应用

设计合成了6个带有烷基链的D-π-A型有机光敏染料应用于染料敏化太阳能电池. 发现长链烷基有利于电池开路光电压的提高. 利用脂肪酸共敏化可进一步提高染料分子的敏化效果, 且提高的程度与脂肪酸的链长有重要关系.     

Theoretical study of quinolines-I(2) intermolecular interaction and implications on dye-sensitized solar cell performance

The monomer and intermolecular charge-transfer complexes of 13 different quinoline derivatives with diiodine were studied using ab initio molecular orbital (MO) and density functional theory (DFT) methods. Calculations revealed that the sigma* orbital of iodine interacts with the nitrogen lone pair in the quinoline ring. The open-circuit photovoltage (V(oc)) values of an Ru(II) complex dye-sensitized nanocrystalline TiO(2) solar cell with an I(-)/I(3) (-) redox electrolyte in acetonitrile using quinoline additives were compared to the computational calculations on the intermolecular interaction between quinolines and I(2). The optimized geometries, frequency analyses, Mulliken population analyses, natural bond orbital (NBO) analyses, and interaction energies indicate that the V(oc) value of the solar cell is higher when quinoline complexes more favorably interact with I(2). Therefore, the interaction between the quinoline additives and iodine redox electrolyte is an important factor for controlling dye-sensitized solar cell performance.     

Aggregation behavior and non-covalent functionalization of borofullerenes B28, B38, and B40: A density functional theory investigation

Fullerene-like boron clusters (borofullerenes) are rising stars in the field of cluster chemistry. In this work, density functional theory calculations revealed that the recently reported small borofullerenes B_n (n = 28, 38, and 40) are all highly reactive and tend to form dimers and even trimers spontaneously. In addition, the non-covalent modification of these borofullerenes by various cycloparaphenylene nanorings can form stable host-guest systems with substantial intermolecular charge transfer at both ground and excited states. Our results demonstrate that the borofullerenes are versatile platform for exohedral functionalization, and are very promising candidates for the design of novel nanomaterials with desirable properties.     

A novel foam based separation strategy for extracting minute target impurities

The purpose of this study was to extract impurities from compounds using a simple separatory bottle to purify target compounds with a foam column and allow for the further characterization of impurities. Charged dyes were used as target compounds due to the ease of detection of dyes and isolated impurities. Foaming agents were used in a glass bottle with a modified cap to separate a target impurity using an appropriately charged ligand. By passing N₂ gas through the solution, the surfactants sodium dodecyl sulfate and cetylpyridinium chloride generated foams that separated the dyes, Methylene blue and Orange G, respectively, from a solution containing both dyes. Sodium dodecyl sulfate condensed Methylene blue from the solution with high purity while cetylpyridinium chloride condensed Orange G with less purity. A range of concentrations (0.01–0.5 mmol/L) of dyes were used for separation. The condensability (volume and/or concentration) of the target compound increased as its concentration decreased. This novel separation method is a simple, rapid, inexpensive, and effective way to prepare samples and allows for the characterization of these impurities using sensitive analytical detection techniques.     

Effect of water hardness on the interaction of cationic dye with anionic surfactants

ABSTRACT

The effect of water hardness causing ions on the critical micelle concentration (cmc) of surfactants was studied using conductivity measurement. Spectrophotometric and conductometric studies of dye and surfactant interaction under the influence of water hardness causing ions were also investigated. It was found that with increasing hardness in water, cmc of the surfactants tends to decrease. The change in the colour of the solution was observed as the degree of hardness increases. Hardness of water can consider as a major contributor of fading or change in colour during washing and cleaning of dyed material. Dye in a surfactant solution containing varying amount of hardness causing ions undergoes a blue shift in the visible region and red shift in ultraviolet region. The comparison between sodium dodecylsulphate (SDS) and saponin natural surfactant showed that turbidity was observed only in the aqueous solution of SDS in the presence of very hard water.     

Eosin Y as a Direct Hydrogen‐Atom Transfer Photocatalyst for the Functionalization of C−H Bonds

Eosin Y, a well‐known economical alternative to metal catalysts in visible‐light‐driven single‐electron transfer‐based organic transformations, can behave as an effective direct hydrogen‐atom transfer catalyst for C?H activation. Using the alkylation of C?H bonds with electron‐deficient alkenes as a model study revealed an extremely broad substrate scope, enabling easy access to a variety of important synthons. This eosin Y‐based photocatalytic hydrogen‐atom transfer strategy is promising for diverse functionalization of a wide range of native C?H bonds in a green and sustainable manner.     

Nanobodies: Chemical Functionalization Strategies and Intracellular Applications

Nanobodies can be seen as next‐generation tools for the recognition and modulation of antigens that are inaccessible to conventional antibodies. Due to their compact structure and high stability, nanobodies see frequent usage in basic research, and their chemical functionalization opens the way towards promising diagnostic and therapeutic applications. In this Review, central aspects of nanobody functionalization are presented, together with selected applications. While early conjugation strategies relied on the random modification of natural amino acids, more recent studies have focused on the site‐specific attachment of functional moieties. Such techniques include chemoenzymatic approaches, expressed protein ligation, and amber suppression in combination with bioorthogonal modification strategies. Recent applications range from sophisticated imaging and mass spectrometry to the delivery of nanobodies into living cells for the visualization and manipulation of intracellular antigens.     

The collagen type I segment long spacing (SLS) and fibrillar forms: Formation by ATP and sulphonated diazo dyes

The collagen type I segment long spacing (SLS) crystallite is a well-ordered rod-like molecular aggregate, ∼300 nm in length, which is produced in vitro under mildly acidic conditions (pH 2.5–3.5) in the presence of 1 mM ATP. The formation of the SLS crystallite amplifies the inherent linear structural features of individual collagen heterotrimers, due to the punctate linear distribution and summation of the bulkier amino acid side chains along the length of individual collagen heterotrimers. This can be correlated structurally with the 67 nm D-banded collagen fibril that is found in vivo, and formed in vitro. Although first described many years ago, the range of conditions required for ATP-induced SLS crystallite formation from acid-soluble collagen have not been explored extensively. Consequently, we have addressed biochemical parameters such as the ATP concentration, pH, speed of formation and stability so as to provide a more complete structural understanding of the SLS crystallite. Treatment of collagen type I with 1 mM ATP at neutral and higher pH (6.0–9.0) also induced the formation of D-banded fibrils. Contrary to previous studies, we have shown that the polysulphonated diazo dyes Direct red (Sirius red) and Evans blue, but not Congo red and Methyl blue, can also induce the formation of SLS-like aggregates of collagen, but under markedly different ionic conditions to those employed in the presence of ATP. Specifically, pre-formed D-banded collagen fibrils, prepared in a higher than the usual physiological NaCl concentration (e.g. 500 mM NaCl, 20 mM Tris-HCl pH7.4 or x3 PBS), readily form SLS aggregates when treated with 0.1 mM Direct red and Evans blue, but this did not occur at lower NaCl concentrations. These new data are discussed in relation to the anion (Cl⁻) and polyanion (phosphate and sulphonate) binding by the collagen heterotrimer and their likely role in collagen fibrillogenesis and SLS formation.