Regioisomeric Effects on the Electronic Features of Indenothiophene‐Bridged D–π‐A′–A DSSC Sensitizers

Two D–π‐A′–A regioisomers (A‐IDT‐D and D‐IDT‐A) featuring 4,4′‐di‐p‐tolyl‐4 H‐indeno[1,2‐b]‐thiophene as a π linker (π) between the diarylamino donor (D) and the pyrimidine–cyanoacrylic acid acceptor (A′–A) have been successfully synthesized and characterized as efficient sensitizers for the dye‐sensitized solar cells (DSSCs). The different arrangements of the D and A′–A blocks on the unsymmetrical indenothiophene (IDT) core render the dipole of IDT being along (A‐IDT‐D) or opposite (D‐IDT‐A) to the direction of intramolecular (donor‐to‐acceptor) charge transfer, and thus induce variations in the physical properties. The experimental observations correlated well with the theoretical analyses, clearly revealing the trade‐off between the molar extinction coefficient (ε) and the S₀→S₁ transition energy. As a result, a superior ε value was observed for D‐IDT‐A, whereas a bathochromic shift in the absorption occurred in A‐IDT‐D. The larger ε value of D‐IDT‐A together with its more favorable energy level relative to TiO₂ led to a higher power conversion efficiency of 7.41 % for the D‐IDT‐A‐based DSSC, retaining approximately 95 % of the N719‐based DSSC efficiency. This work manifests the clear structure–property relationship for the case of donor and acceptor components being connected by an unsymmetrical π linker and provides insights for molecular engineering of organic sensitizers.     

Pseudohalogenogermylenes versus Halogenogermylenes: Difference in their Complexation Behavior towards Group 6 Metal Carbonyls

Pseudohalogenogermylenes [(iBu)₂ATI]GeY (Y=NCO 4 , NCS 5 ) show different coordination behavior towards group 6 metal carbonyls in comparison to the corresponding halogenogermylenes [(iBu)₂ATI]GeX (X=F 1 , Cl 2 , Br 3 ) (ATI=aminotroponiminate). The reactions of compounds 4 – 5 and 1 – 3 with cis‐[M(CO)₄(COD)] (M=Mo, W, COD=cyclooctadiene) gave trans‐germylene metal complexes {[(iBu)₂ATI]GeY}₂M(CO)₄ (Y=NCO, M=Mo 6 , W 11 ; Y=NCS, M=Mo 7 ) and cis‐germylene metal complexes {[(iBu)₂ATI]GeX}₂M(CO)₄ (M=Mo, X=F 8 , Cl 9 , Br 10 ; M=W, X=Cl 12 ), respectively. Theoretical studies on compounds 7 and 9 reveal that donor–acceptor interactions from Mo to Ge atoms are better stabilized in the observed trans and cis geometries than in the hypothetical cis and trans structures, respectively.     

Dual-stimuli responsive PNiPAM microgel achieved via layer-by-layer assembly: magnetic and thermoresponsive

We describe the synthesis, characterisation and surface-modification of magnetic nanoparticles and a poly(N-isopropylacrylamide) microgel, followed by the assembly and characterisation of magnetic nanoparticles on the microgel. To facilitate this deposition, the surface of the microgel is first modified via the layer-by-layer assembly of polyelectrolytes. One advantage of this concept is that it allows an independent optimization and fine tuning of the magnetic and thermoresponsive properties of individual components (nanoparticles and microgels) before assembling them so that the hybrid core-shell structure retains all the individual properties. The decisive parameter when exploiting the thermoresponsive and magnetic properties in such hybrid core-shell structures is the amount of heat transfer from the magnetic core onto the thermosensitive (loaded) microgel (for the subsequent heat-triggered release of drugs). Inductive heat study reveals that the heat generated by the magnetic nanoparticles is sufficient to cause the collapse of the microgel above its volume phase transition temperature. Successful confinement of positively and negatively charged magnetic nanoparticles between polyelectrolyte layers is achieved using the layer-by-layer deposition onto the microgel. Dynamic light scattering measurements show (i) the presence of each layer successfully deposited, (ii) the preservation of thermoresponsivity in the coated microgel, and (iii) that the magnetic nanoparticles do not get detached during the phase transition of the microgel. Electrophoresis measurements confirm charge reversal at every stage of layering of polycations, polyanions and magnetic nanoparticles. This unique combination of thermoresponsivity and magnetism opens up novel perspectives towards remotely controlled drug carriers.     

Validated reversed-phase column high-performance liquid chromatographic method for separation and quantification of polyphenolics and furocoumarins in herbal drugs

A rapid column high-performance liquid chromatographic-photodiode array method has been developed for the separation and identification of secondary metabolites, especially different types of phenols and furocoumarins, in a 35 min chromatographic run. The method has been optimized and validated for selectivity, precision, recovery, and robustness with the aim of application for standardization of selected herbal drugs. Almost all of the tested compounds had linearity of >98%, with relative standard deviation <10% in terms of variation of retention time. Interday and intraday variability was <5%. The developed method has been successfully applied in identification and quantification of phenols and furocoumarins present in different plants, viz., Artemisia pallens (whole plant), Hibiscus rosa-sinensis DC (flower), Heracleum candicans DC (fruit), and Ficus carica Linn (bark). The results indicate that the method is rapid, accurate, and robust for the analysis of different types of phenols and furocoumarins and, hence, can be successfully used in the quality control and standardization of plant extracts and herbal drugs.     

Existence and regularity of solutions to nonlocal retarded differential equations

In this paper the existence and uniqueness of different types of solutions to a class of semilinear retarded differential equations with nonlocal history conditions are obtained by a fixed point argument. Also finite dimensional approximation of these solutions in a Hilbert space is established.     

Investigation of Cu and Co multilayer deposition in aqueous ambient

Electrochemical preparation of multilayers of Cu/Co(Cu) has been investigated using cyclic voltammetry and in situ atomic force microscopy. Potentiostatic pulse deposition of Copper and Cobalt has been shown to reduce the surface roughness of the electrodeposits. Multilayers of Cu/Co(Cu) have been grown electrochemically using pulse deposition technique. Formation of coherent multilayers has been demonstrated using grazing angle X-ray diffraction studies.     

Preparation and characterization of manganese ferrite-based magnetic liposomes for hyperthermia treatment of cancer

Comparative evaluation of two different methods of magnetic liposomes preparation, namely thin film hydration (TFH) and double emulsion (DE) with different molar ratios of egg-phosphatidyl choline (egg-PC) and cholesterol using lauric acid coated manganese ferrite-based aqueous magnetic fluid, is reported. TFH was found to be a better method of encapsulation and TFH 2:1 (egg-PC: cholesterol) magnetic liposomes showed the highest encapsulation efficiency and comparable heating ability to that of magnetic fluids. Stealth TFH 2:1 magnetic liposomes containing DSPE-PEG₂₀₀₀ were three-fold more cytocompatible as compared to the magnetic fluid. Stealth TFH 2:1 manganese ferrite-based magnetic liposomes might be useful for hyperthermia treatment of cancer.     

Sc(OTf)3 catalysed multicomponent synthesis of chromeno[2,3-d]pyrimidinetriones under solvent-free condition

An efficient, simple, and environmentally friendly synthesis of a series of chromeno[2,3-d]pyrimidine-trione derivatives has been accomplished via the three-component reaction of a barbituric acid, dimedone/cyclohexane-1,3-dione, and aromatic aldehydes using Sc(OTf)₃ as a recyclable catalyst under solvent-free condition. This method exploits the use of Sc(OTf)₃ as a Lewis acid catalyst in organic synthesis and offers many rewards such as excellent product yield and easy work-up procedure. Harmless reaction conditions, as well as the absence of side-products, are another green aspects of this protocol.     

Synthesis and characterization of triorganoantimony(V) complexes with bidentate ligands

Monochelated organoantimony(V) complexes of the type R₃Sb(OMe)L, where R = Me or Ph, and L is the anion of acetylacetone, 8-hydroxyquinoline, salicylaldehyde, o-hydroxyacetophenone or 2-hydroxy-1-naphthaldehyde have been obtained from triorganoantimony(V) dibromide and the sodium derivative of the ligands in a benzene-methanol mixture. Molecular weight determination in benzene reveals the monomeric nature of these complexes. IR and NMR data suggest that L acts as a bidentate ligand giving an octahedral environment for the antimony atom.