A Pure-Red Doublet Emission with 90 % Quantum Yield: Stable,Colorless, Iodinated Triphenylmethane Solid

Red luminescence is found in off-white tris(iodoperchlorophenyl)methane ( 3I-PTM^H ) crystals which is characterized by a high photoluminescence quantum yield (PLQY 91 %) and color purity (CIE coordinates 0.66, 0.34). The emission originates from the doublet excited state of the neutral radical 3I-PTM^R , which is spontaneously formed and becomes embedded in the 3I-PTM^H matrix. The radical defect can also be deliberately introduced into 3I-PTM^H crystals which maintain a high PLQY with up to 4 % radical concentration. The immobilized iodinated radical demonstrates excellent photostability (estimated half-life >1 year under continuous irradiation) and intriguing luminescent lifetime (69 ns). TD-DFT calculations demonstrate that electron-donating iodine atoms accelerate the radiative transition while the rigid halogen-bonded matrix suppresses the nonradiative decay.     

Improvement of GC‐MS Analysis of Shahrbabak Ziziphora tenuior Essential Oil by Using Multivariate Curve Resolution Approaches

Essential oil of aerial parts of Ziziphora tenuior growing in Shahrbabak in central Iran are isolated by hydrodistillation. Due to complexity of essential oils, there are fundamental problems such as co‐elution in their direct gas chromatography‐mass spectrometry analysis. These problems can result in low similarity matches in MS library search, so that true identification and determination of individual components may fail. In the present work, each component was identified and determined using GC‐MS coupled with multivariate curve resolution (MCR) techniques. In this way, more information along with higher accuracy and precision can be extracted from pure experimental GC‐MS data. The number of identified components found increased from 37 in direct similarity search to 80 in GC‐MS/MCR method. To identify each individual component, similarity search and Kovat's retention index comparison were implemented. The results found showed that pulegone (38.3%), 3′,5′‐dihydroxyacetophenone (22.83%), isomenthone (7.06%), 2‐methyl‐5‐(1‐methylethyl)‐phenol (3.41%), limonene (2.59%) and 2‐acetyl‐4,4‐dimethyl‐cyclopent‐2‐enone (2.49%) were the most abundant components. The reported compounds accounted for 94.39% of total content of the essential oil. A characteristic feature of the Iranian Ziziphora tenuior is the absence of piperitenone in its constituents compared with the oil of other Ziziphora species from Turkey.     

DFT Study of the Mechanism and Regioselectivity of 1,3-Pentadiene with Methyl Acrylate Using Theoretical Approaches

<正>Ab initio density functional theory (DFT) calculations have been used to study regioselectivity in the Diels-Alder (DA) cycloaddition reaction between 1,3-pentadiene and methyl acrylate. The DFT calculations were performed with the B3LYP functional and 6-311+G~(**) basis set. Two synchronous transition structures corresponding to the formation of different regioisomers associated with the two reaction channels have been located. The DFT calculations generated transition geometries with a very small degree of asynchronicity. The present analysis shows that these reactions have normal electron demand (NED) character. Moreover, the results obtained from energetic and electronic approaches with the exception of Houk's rule confirm that ortho regioisomer is the major product.     

One-pot synthesis of 3-hydroxymaleic anhydrides by cyclization of 1,1-bis(trimethylsilyloxy)ketene acetals with oxalyl chloride

Functionalized 3-hydroxymaleic anhydrides were prepared by cyclization of 1,1-bis(trimethylsilyloxy)ketene acetals with oxalyl chloride.     

A new strategy for the chemoselective sulfonamide N-alkylation of sulfonyl ureas under neutral and mild conditions

An efficient and chemoselective sulfonamide N-alkylation of sulfonyl ureas is described. The sulfonyl urea derivatives, prepared in situ by the addition of an amine to an arylsulfonyl isocyanate, are selectively alkylated in excellent yields under neutral and mild conditions by treatment with trialkylphosphite-dimethyl acetylenedicarboxylate at ambient temperature.     

Cyclodextrin‐modified capillary electrophoresis for achiral and chiral separation of ergostane and lanostane compounds extracted from the fruiting body of Antrodia camphorata

A CD‐modified capillary electrophoretic method has been developed for achiral and chiral analysis of seven bioactive compounds isolated from the fruiting body of Antrodia camphorata. Such important target analytes exhibit similar chemical structures and are known for their diverse properties including antioxidant and anticancer effects. The analytes were separated in 25 min using a pH 9.3, 20 mM sodium borate buffer containing 20 mM methyl‐β‐CD and 30 mM sulfobutylether‐β‐CD. With the exception of the optical isomer pairs (antcin B or zhankuic acid A, zhankuic acid C, and antcin A), the remaining bioactive compounds including the chiral pair antcin C were baseline‐separated. Analysis time was noticeably longer to baseline separate all of the above chiral pairs (～38 min) by adding 5% DMF to the running buffer. The migration order was reversed compared with the HPLC elution. More hydrophobic compounds complexed favorably with methyl‐β‐CD and emerged earlier in the electropherogram than their more hydrophilic counterparts which were strongly associated with sulfobutylether‐β‐CD. The simple capillary electrophoretic method developed was applicable for rapid separation and characterization of several important bioactive compounds isolated from the fruiting body of A. camphorata.     

Investigations on the redox behaviour of manganese in manganese(II)–saccharin and manganese(II)–saccharin–1,10-phenanthroline complexes

The redox behaviour of manganese system in Mn–Sac and Mn–Sac–Phen complexes were studied using cyclic voltammetry technique at glassy carbon electrode (GCE) in 0.1 M KCl electrolyte. The CV of Mn–Sac solution is more or less similar to that of uncoordinated Mn (in MnCl₂) accept slight difference in peak position and peak current. The presence of secondary ligand phenanthroline (in Mn–Sac–Phen complex) changes the CV of Mn system largely compared to those of uncoordinated Mn and Mn–Sac. The redox system is irreversible in Mn–Sac and quasi-reversible in Mn–Sac–Phen complex. The effect of concentration and pH on the redox behaviour of Mn system have been studied for both the complexes.     

Wake potential in a self-gravitating dusty plasma

Using a test particle approach, the dynamical wake potential has been examined in a homogeneous self-gravitating dusty plasma. The periodic oscillatory potential might lead to an alternative approach to the Jeans instability for the formation of dust agglomeration leading to gravitational collapse of the self-gravitating systems.     

Modulation instability of lower hybrid waves leading to cusp solitons in electron–positron(hole)–ion Thomas Fermi plasma

Following the idea of three‐wave resonant interactions of lower hybrid waves, it is shown that quantum‐modified lower hybrid (QLH) wave in electron–positron–ion plasma with spatial dispersion can decay into another QLH wave (where electron and positrons are activated, whereas ions remain in the background) and another ultra‐low frequency quantum‐modified ultra‐low frequency Lower Hybrid (QULH) (where ions are mobile). Quantum effects like Bohm potential and Fermi pressure on the lower hybrid wave significantly reshaped the dispersion properties of these waves. Later, a set of non‐linear Zakharov equations were derived to consider the formation of QLH wave solitons, with the non‐linear contribution from the QLH waves. Furthermore, modulational instability of the lower hybrid wave solitons is investigated, and consequently, its growth rates are examined for different limiting cases. As the growth rate associated with the three‐wave resonant interaction is generally smaller than the growth associated with the modulational instability, only the latter have been investigated. Soliton solutions from the set of coupled Zakharov and NLS equations in the quasi‐stationary regime have been studied. Ordinary solitons are an attribute of non‐linearity, whereas a cusp soliton solution featured by nonlocal nonlinearity has also been studied. Such an approach to lower hybrid waves and cusp solitons study in Fermi gas comprising electron positron and ions is new and important. The general results obtained in this quantum plasma theory will have widespread applicability, particularly for processes in high‐energy plasma–laser interactions set for laboratory astrophysics and solid‐state plasmas.     

Three-dimensional computational fluid dynamics modeling of proton exchange membrane electrolyzer with new flow field pattern

Journal of Thermal Analysis and Calorimetry - The performance of a proton exchange membrane electrolyzer cell directly depends on the arrangement of flow field in bipolar plates (BPs). The design...