Synthesis of novel benzopyrano[3,2-c]coumarins via tandem base promoted nucleophilic substitution and intramolecular electrophilic aromatic cyclization

Efficient and facile synthesis of 7H-benzopyrano[3,2-c]coumarins has been achieved by mild base promoted reaction of 4-chloro-3-formylcoumarin with diversely functionalized resorcinols. All the products were obtained as pure precipitates from the reaction mixture and the structure of the product was confirmed by X-ray analysis.     

Impact of symmetry-breaking of non-fullerene acceptors for efficient and stable organic solar cells

The concurrent enhancement of short-circuit current (J_SC) and open-circuit voltage (V_OC) is a key problem in the preparation of efficient organic solar cells (OSCs). In this paper, we report efficient and stable OSCs based on an asymmetric non-fullerene acceptor (NFA) IPC-BEH-IC2F. The NFA consists of a weak electron-donor core dithienothiophen[3,2-b]-pyrrolobenzothiadiazole (BEH) and two kinds of strong electron-acceptor (A) units [9H-indeno[1,2-b]pyrazine-2,3-dicarbonitrile (IPC) with a tricyclic fused system and 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (IC2F)]. For comparison, the symmetric NFAs IPC-BEH-IPC and IC2F-BEH-IC2F were characterised. The kind of flanking A unit significantly affects the light absorption features and electronic structures of the NFAs. The asymmetric IPC-BEH-IC2F has the highest extinction coefficient among the three NFAs owing to its strong dipole moment and highly crystalline feature. Its highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels lie between those of the IPC-BEH-IPC and IC2F-BEH-IC2F molecules. The IPC group also promotes molecular packing through the tricyclic π-conjugated system and achieves increased crystallinity compared to that of the IC2F group. Inverted-type photovoltaic devices based on p-type polymer:NFA blends with PBDB-T and PM6 polymers as p-type polymers were fabricated. Among all these devices, the PBDB-T:IPC-BEH-IC2F blend device displayed the best photovoltaic properties because the IPC unit provides balanced electronic and morphological characteristics. More importantly, the PBDB-T:IPC-BEH-IC2F-based device exhibited the best long-term stability owing to the strongly interacting IPC moiety and the densely packed PBDB-T:IPC-BEH-IC2F film. These results demonstrate that asymmetric structural modifications of NFAs are an effective way for simultaneously improving the photovoltaic performance and stability of OSCs.

A 9H-indeno[1,2-b]pyrazine-2,3-dicarbonitrile (IPC) moiety in asymmetric non-fullerene acceptors promotes the formation of a densely packed crystalline structure, enabling efficient and long-term stable organic solar cells.     

Solid phase extraction vis-à-vis coprecipitation preconcentration of cadmium and lead from soils onto 5,7-dibromoquinoline-8-ol embedded benzophenone and determination by FAAS

This article compares the solid phase extraction (SPE) and coprecipitative preconcentration of cadmium and lead from dilute aqueous solutions as a function of pH and weight of chelating agent. SPE enriches cadmium and lead over a wider pH range (6.0-8.0) and requires lower weight of DBQ chelate embedded benzophenone. Among the quinoline-8-ol and its dihaloderivatives, DBQ embedded benzophenone allows quantitative enrichment over a wide pH range (6.0-8.0) for both cadmium and lead unlike DCQ (∼6.5 for Cd and 6.5-7.0 for Pb), DBQ was preferred. The calibration plots were rectilinear over the concentration range of 0.1-50 and 2.5-200 μg l⁻¹ of cadmium and lead with detection limits of 0.1 and 2.0 μg l⁻¹, respectively, which are 400 times lower than the direct FAAS method. The precision of the developed procedure is good as it provides relative standard deviation values of 2.20 and 2.45% during five replicate determinations of 2 and 25 μg l⁻¹ of cadmium and lead, respectively. The accuracy of the developed procedure was tested by analyzing certified reference materials (CRM's) of soil and marine sediment samples supplied by IAEA, Italy and NRC, Canada, respectively. Furthermore, the developed procedure has been successfully used for the speciative determination of cadmium and lead in soil samples collected from the vicinity of industries in India.     

Solid-phase synthesis of BODIPY dyes and development of an immunoglobulin fluorescent sensor

The diversification of the BODIPY scaffold has been hindered by its controversial adaptability to solid-phase chemistry. Herein we report the first solid-phase synthesis of a BODIPY library in high purities. We screened the library against a set of proteins, identified an immunoglobulin fluorescent sensor (Ig Orange) and confirmed its binding by SPR experiments.     

Solid Phase Extractive Preconcentration of Cobalt and Nickel in Hair Samples Using Ethyl Xanthate Modified Benzophenone

The ethyl xanthate complexes of cobalt and nickel are quantitatively retained on benzophenone in the pH range of 8.0–10.0. The solid mixture consisting of metal complex together with benzophenone is dissolved in 5mL of dimethyl formamide, and the cobalt and nickel contents were determined by flame atomic absorption spectrometry. The calibration graphs are rectilinear over the concentration range of 0–75 (Co) and 0–100 (Ni) µgL^–1. The detection limits of flame AAS for cobalt and nickel are lowered by a factor of 200 due to the solid phase extraction preconcentration procedure. NIES CRM Human Hair No. 5 and IAEA Reference Hair HH-1 certified reference materials were used in order to verify the accuracy of the developed preconcentration method in analysing human hair samples. The results obtained were found to be in excellent agreement with certified values. Furthermore, hair samples collected from various inhabitants of different age groups and sex living in the Indian states of Andhra Pradesh and Tamil Nadu were successfully analysed by flame AAS in conjunction with the solid phase extraction preconcentration procedure developed for cobalt and nickel.     

Further shortening of the C-C single bond in substituted tetrahedranyl tetrahedrane systems: an energy decomposition analysis

The computational study explores the electronic fine tuning of the exocyclic C-C single bond length in tetrahedranyl tetrahedrane as a function of various substituents. The factors which determine the bond lengths and bond strengths are examined by using the EDA method.     

Nanosized paclitaxel particles from supercritical carbon dioxide processing and their biological evaluation

The rapid expansion of a supercritical solution into a liquid solvent (RESOLV) technique with benign supercritical carbon dioxide was applied to obtain aqueous suspended nanoparticles of the highly potent anticancer drug paclitaxel. The paclitaxel nanoparticles were protected from agglomeration by using a known nontoxic stabilization agent. The aqueous suspended paclitaxel nanoparticles of different average particle sizes were evaluated in vitro against human breast cancer cells. The results suggest that the nanosized paclitaxel particles are effective, with an antineoplastic activity comparable to that of the commercial paclitaxel formulation. The technique should be generally applicable to the processing of nanoparticles from other important drugs with aqueous solubility problems.     

Gold(I)-catalyzed unprecedented rearrangement reaction between 2-aminobenzaldehydes with propargyl amines: an expedient route to 3-aminoquinolines

Access to aminoquinolines: a gold(I)-catalyzed unprecedented rearrangement reaction between 2-aminobenzaldehydes with propargyl amine was studied. The study provided, for the first time, direct access to 3-aminoquinolines in one step starting from readily available starting materials. Elegantly designed experiments were employed to unravel the mechanism of this unprecedented rearrangement, which are corroborated by DFT calculations.     

Energy decomposition analysis of cation–π, metal ion–lone pair,hydrogen bonded,charge‐assisted hydrogen bonded,and π–π interactions

This study probes the nature of noncovalent interactions, such as cation–π, metal ion–lone pair (M–LP), hydrogen bonding (HB), charge‐assisted hydrogen bonding (CAHB), and π–π interactions, using energy decomposition schemes—density functional theory (DFT)–symmetry‐adapted perturbation theory and reduced variational space. Among cation–π complexes, the polarization and electrostatic components are the major contributors to the interaction energy (IE) for metal ion–π complexes, while for onium ion–π complexes ( , , , and ) the dispersion component is prominent. For M–LP complexes, the electrostatic component contributes more to the IE except the dicationic metal ion complexes with H₂S and PH₃ where the polarization component dominates. Although electrostatic component dominates for the HB and CAHB complexes, dispersion is predominant in π–π complexes.Copyright © 2015 Wiley Periodicals, Inc.