White and Red Organic Light Emitting Materials

Derivatives of 2,3-(1,4-dialkoxyaceno)norbornadiene underwent ring-opening metathesis polymerization (ROMP) upon the catalysis of a ruthenium complex to afford the corresponding polymers. The polymeric materials containing anthracene chromophores emit white electro-luminescence, which can be fabricated into light-emitting diodes (LED). The broad emission band is composed of a blue emission from anthracene and a red emission from aggregates. A single layer device, ITO/polymer/Ca/Al, can be turned on at 7V and exhibits maximum intensity 427 cd/m2 at 15 V. A double layer device, ITO/polymer/TPBI/Mg:Ag (TPBI = (2,2′,2"-(1,3,5-benzenetriyl)-tris(1-phenyl-1H-benzimidazole)) displayed blue light with turn-on voltage 6 V and maximal intensity 930 cd/m2 at 15 V.Derivatives of bisindolylmaleimide were found to form amorphous solid films which exhibit intensive red luminescence. The property of forming glasses can be ascribed to the nonplanar geometry of these molecules. LED devices were fabricated by a layer of pure dye sandwiched between two charge transporting films. The yellow emission spectrum of the devices utilizing Alq (tris(8-hydoxyquinolinato)aluminum) contains a green component from Alq. Pure red emissions can be achieved by replacing Alq with TPBI. Typical devices can be turned on at ～3 V with maximal intensity 2000 cd/m2. White color devices are under current investigation, in which the green Alq layer is replaced by its blue derivative (bis(2-methyl-8-hydoxyquinolinato)(phenolato)aluminum).     

Photoinduced electron transfer across linearly fused oligo-norbornyl structures

The rates of photoinduced electron transfer (ET) reactions across two oligo-norbornyl spacer groups (S), that is, structure 1 fused by two norbornadiene (NBD) units and structure 2 fused by three NBD units, are examined. Substituted naphthalene acted as an electron donor (D), whilst ethylene-1,2-dicarboxylate as an electron acceptor (A). ET rates were measured by fluorescence quenching experiments on these D-S-A dyads, and the results were correlated with reaction free energies according to the Marcus relationship. It was found that naphthalene with phenyl substituents showed relatively slower ET rates. The conformational flexibility of phenyl substituents may cause a hindrance on the electronic coupling between D and A. Another salient feature was the abnormally high quenching rates observed in nonpolar solvents such as cyclohexane, the results of which may be ascribed to a competing energy transfer process.     

Piptigrine, a new insecticidal amide from Piper nigrum Linn

A new insecticidal amide piptigrine (1) possessing highly extended conjugation was isolated from the dried ground seeds of Piper nigrum Linn. along with the known amides piperine and wisanine (hitherto unreported from this plant). The structure of 1 has been elucidated as 1-[9-(3',4'-methylenedioxyphenyl)-4E,6E,8E-nonatrienoyl]piperidine through extensive 1D- and 2D-NMR (COSY-45, NOESY, J-resolved, HMQC, HMBC and NOESY studies. The known compounds have been identified through comparison of their spectral data with those reported in literature. 1 exhibited toxicity of 15.0 ppm against fourth instar larvae of Aedes aegypti Liston.     

Impact of Various Parameters Over the Stability of Water-in-Vegetable Oil Emulsion

Theory regarding emulsification, its coalescence and impact of emulsifier over its stability has been updated. For the verification of the proposed theory, water-in-oil emulsion was prepared by mixing water and soybean oil in the presence and absence of emulsifier, monoglyceride. The effect of different parameters like emulsification time, contents of water, and concentration of emulsifier has been investigated on the emulsification and coalescence process of the emulsion. It was noted that the emulsion quality was highest if the mixture was homogenized for about 15 minutes and the water contents were 40% v/v. The addition of monoglyceride up to 0.5% w/v gave the most stable emulsion having higher quality than other composition. The results obtained were compared with the proposed theory and found to have good compositions.      

Plasma-Assisted ALD of Highly Conductive HfNx: On the Effect of Energetic Ions on Film Microstructure

Plasma Chemistry and Plasma Processing - In this work, we report on the atomic layer deposition (ALD) of HfNx thin films by employing CpHf(NMe2)3 as the Hf(IV) precursor and Ar–H2 plasma in...     

Additive manufacturing for energy storage: Methods,designs and material selection for customizable 3D printed batteries and supercapacitors

Additive manufacturing and 3D printing in particular have the potential to revolutionize existing fabrication processes, where objects with complex structures and shapes can be built with multifunctional material systems. For electrochemical energy storage devices such as batteries and supercapacitors, 3D printing methods allows alternative form factors to be conceived based on the end use application need in mind at the design stage. Additively manufactured energy storage devices require active materials and composites that are printable, and this is influenced by performance requirements and the basic electrochemistry. The interplay between electrochemical response, stability, material type, object complexity and end use application are key to realising 3D printing for electrochemical energy storage. Here, we summarise recent advances and highlight the important role of methods, designs and material selection for energy storage devices made by 3D printing, which is general to the majority of methods in use currently.     

High Na+ Mobility in rGO Wrapped High Aspect Ratio 1D SbSe Nano Structure Renders Better Electrochemical Na+ Battery Performance

We chose to understand the cyclic instability and rate instability issues in the promising class of Na⁺ conversion and alloying anodes with Sb₂Se₃ as a typical example. We employ a synthetic strategy that ensures efficient rGO (reduced graphene oxide) wrapping over Sb₂Se₃ material. By utilization of the minimum weight of additive (5 wt.% of rGO), we achieved a commendable performance with a reversible capacity of 550 mAh g⁻¹ at a specific current of 100 mA g⁻¹ and an impressive rate performance with 100 % capacity retention after high current cycling involving a 2 Ag⁻¹ intermediate current step. The electrochemical galvanostatic intermittent titration technique (GITT) has been employed for the first time to draw a rationale between the enhanced performance and the increased mobility in the rGO wrapped composite (Sb₂Se₃-rGO) compared to bare Sb₂Se₃. GITT analysis reveals higher Na⁺ diffusion coefficients (approx. 30 fold higher) in the case of Sb₂Se₃-rGO as compared to bare Sb₂Se₃ throughout the operating voltage window. For Sb₂Se₃-rGO the diffusion coefficients in the range of 8.0×10⁻¹⁵ cm² s⁻¹ to 2.2×10⁻¹² cm² s⁻¹ were observed, while in case of bare Sb₂Se₃ the diffusion coefficients in the range of 1.6×10⁻¹⁵ cm² s⁻¹ to 9.4×10⁻¹⁵ cm² s⁻¹ were observed.     

Density functional theory analysis of a mixed‐ligand iridium compound for multi‐color organic light‐emitting diodes

Electronic states and their energies are calculated for a mixed‐ligand Ir(III) compound, (5‐chloro‐8‐hydroxyquinoline) bis(2‐phenylpyridyl) iridium (called IrQ(ppy)₂‐5Cl) using time‐dependent density functional theory (TDDFT) calculations and are compared with the experimental result. A good agreement is obtained between the calculated and measured absorption spectra. The d‐π_Q* molecular orbital transition gives the lowest‐energy triplet state absorption band. Its energy is estimated as 1.84 eV (671 nm), which is close to the absorption band position of 1.86 eV (666 nm) observed for IrQ(ppy)₂‐5Cl doped in 4,4′‐N,N′‐dicarbazole‐biphenyl (CBP) host and of 1.88 eV (660 nm) observed for IrQ(ppy)₂‐5Cl doped in polystyrene (PS). The second triplet state absorption band is caused by d‐π_ppy transition. Its position is calculated as 2.51 eV (494 nm). The dipole moment is estimated as 3.45 D, which is lower than the dipole moment of fac‐Ir(ppy)₃. This is understood by a reduced charge transfer between Ir(III) and quinoline ligand. Copyright © 2008 John Wiley & Sons, Ltd.     

Phytochemical studies on the seed extract of Piper nigrum Linn

The petroleum ether extract of dried ground seeds of Piper nigrum Linn. and some column fractions of this extract were subjected to GC and GC-MS analysis, resulting in the identification of fourteen compounds (1-14) by using NIST Mass spectral search program 1998 and the Kovat's retention indices. Ten of the compounds (1, 2, 4-12) are reported for the first time from this plant. All the fractions showed insecticidal activity against the fourth instar larvae of Aedes aegypti and against the fourth instar larvae of Anopheles stephensi Liston, determined by the WHO method.     

New insecticidal amides from petroleum ether extract of dried Piper nigrum L. whole fruits

The petroleum ether extract of dried ground whole fruits of Piper nigrum L. afforded 20 compounds (1-20) including two new insecticidal amides named as pipnoohine (1), and pipyahyine (2), seven reported for the first time from this plant (12, 13, 15-17, 19, 20), and eleven known compounds (3-11, 14, 18). The structure of 1 has been elucidated as (2E,4E,12Z)-N-(4-methylpentyl)octadeca-2,4,12-trienamide and that of 2 as (2E,4E,11E)-12-(benzo[1,3]dioxol-5-yl)-N-(3-methylbutyl)dodeca-2,4,11-trien-amide through extensive ID-, 2D-NMR spectral studies and chemical reactions. The known compounds have been identified through comparison of their spectral data with those reported in literature. 1 and 2 exhibited toxicity at 35.0 and 30.0 ppm respectively against fourth instar larvae of Aedes aegypti L. by WHO method.