Synthesis and electroluminescent studies of blue‐emitting copolymers containing phenylene vinylene and oxadiazole moieties in the main chain

Two statistical copolymers III and IV combining features of the two reference polymers I and II were synthesized by a Wittig reaction with the objective of raising the electron‐transport properties and fluorescence quantum yields relative to the alternating block copolymers I and II . The electroluminescent properties of single‐layer LEDs using these copolymers were studied. External quantum efficiencies of 0.035 and 0.11% were obtained from single‐layer devices on the basis of III and IV , respectively, which are higher than those of similar devices using I and II . Two single‐layer LEDs using a blend of I and II (4:1 and 1:1 wt/wt) corresponding to the compositions of copolymers III and IV , respectively, were also fabricated for comparison. Results indicated that the covalent incorporation of oxadiazole is effective in improving the efficiency of LEDs and that the molar content of oxadiazole plays an important role in the performance of the devices. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 235–241, 2002     

The synthesis and characterization of a porphyrazine bearing aza-15-crown-5 moieties in the peripheral positions and its cobalt(II) complex

The synthesis of novel metal-free (H₂-Pz) and metalloporphyrazines (MgPz and CoPz), peripherally substituted with eight aza-15-crown-5 moieties, is described. The novel compounds were characterized by elemental analysis, i.r, ¹H and ¹³C-n.m.r, UV–vis and m.s. spectral data.     

Effects of Heavy Iodine Atoms and π-Expanded Conjugation on Charge Transfer Dynamics in Carboxylic Acid BODIPY Derivatives as Triplet Photosensitizers

Borondipyrromethene (BODIPY) chromophores are composed of a functional-COOH group at meso position with or without a biphenyl ring, and their compounds with heavy iodine atoms at −2, −6 positions of the BODIPY indacene core were synthesized. The photophysical properties of the compounds were studied with steady-state absorption and fluorescence measurements. It was observed that the absorption band is significantly red-shifted, and fluorescence signals are quenched in the presence of iodine atoms. In addition to that, it was indicated that the biphenyl ring does not affect the spectral shifting in the absorption as well as fluorescence spectra. In an attempt to investigate the effect of π-expanded biphenyl moieties and heavy iodine atoms on charge transfer dynamics, femtosecond transient absorption spectroscopy measurements were carried out in the environment of the tetrahydrofuran (THF) solution. Based on the performed ultrafast pump-probe spectroscopy, BODIPY compounds with iodine atoms lead to intersystem crossing (ISC) and ISC rates were determined as 150 ps and 180 ps for iodine BODIPY compounds with and without π-expanded biphenyl moieties, respectively. According to the theoretical results, the charge transfer in the investigated compounds mostly appears to be intrinsic local excitations, corresponding to high photoluminescence efficiency. These experimental findings are useful for the design and study of the fundamental photochemistry of organic triplet photosensitizers.     

Miscellaneous PEDOT:PTS (polythiophenesulfonyl chloride) based conductive binder for silicon anodes in lithium ion batteries

Lithium ion batteries which are an energy storage system have increasing attention owing to suitability and advantages for many applications. Although it has ideal specifications, the capacity properties still have to be developed. In this study, the electrical conductivity of the anode was increased by using a conductive polymer binder and the active material content of the anode was also enhanced without adding carbon additives. Silicon based anodes were manufactured by using poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate (PEDOT:PSS) and poly(3,4-ethylenedioxythiophene)/polythiophenesulfonyl chloride (PEDOT:PTS) conductive polymer binders. Si/PEDOT:PTS anode showed about 2000 mAh/g specific capacities after 60 cycles with decreasing impedance.     

An Oxidative Rearrangement of 6‐Phenylbicyclo[3.2.0]heptan‐6‐ol to 1,1′‐Biphenyl‐Carbaldehydes: A Mechanistic Study

Acid‐catalyzed rearrangement of 6‐phenylbicyclo[3.2.0]heptan‐6‐ol gave 1,1′‐biphenyl and 1,1′‐biphenyl‐carbaldehydes in small amounts as well as the expected rearrangement products. A detailed study of the reaction mechanism revealed that the conversion occurs via an oxidative process through the consecutive formation of cycloheptadienes, cycloheptatrienes, and 1,1′‐biphenyls. The acid‐catalyzed rearrangement of 6‐phenylbicyclo[3.2.0]hept‐2‐en‐6‐ols gave 1‐ and 2‐phenylcycloheptatrienes directly, from which 1,1′‐biphenyl and 1,1′‐biphenyl‐carbaldehydes were obtained by oxidation.     

Investigation of irradiated 1H-Benzo[b]pyrrole by ESR,thermal methods and learning algorithm

1H-Benzo[b]pyrrole samples were irradiated in the air with gamma source at 0.969?kGy per hour at room temperature for 24, 48 and 72?h. After irradiation, electron spin resonance, thermogravimetry analysis (TGA) and differential thermal analysis (DTA) measurements were immediately carried out on the irradiated and unirradiated samples. The ESR measurements were performed between 320 and 400?K. ESR spectra were recorded from the samples irradiated for 48 and 72?h. The obtained spectra were observed to be dependent on temperature. Two radical-type centres were detected on the sample. Detected radiation-induced radicals were attributed to R-^+?NH and R=^?CC₂H₂. The g-values and hyperfine constants were calculated by means of the experimental spectra. It was also determined from TGA spectrum that both the unirradiated and irradiated samples were decomposed at one step with the rising temperature. Moreover, a theoretical study was presented. Success of the machine learning methods was tested. It was found that bagging techniques, which are widely used in the machine learning literature, could optimise prediction accuracy noticeably.     

Linear trinuclear mixed valance MnIII-MnII-MnIII complex: Synthesis,crystal structure and characterization

A new linear trinuclear Mn^III-Mn^II-Mn^III complex 1 has been synthesized and characterized by elemental, spectral, X-ray and magnetic analysis. X-ray diffraction studies show that the central Mn^II ion is located at a crystallographic inversion center and is triply bridged to the terminal Mn^III ions through one methoxide, one syn-syn carboxylate and one hydroxyl oxygen bridges with the short Mn^III…Mn^II distance that is 3.047 Å. The intermolecular C-H…O, C-H…π and ring-metal interactions are observed in the hydrogen-bonded assembly of 1. Magnetic studies reveal that the mixed-valence complex 1 has S = 3/2 ground state with antiferromagnetic exchange interactions between Mn^II and Mn^III ions.     

Synthesis, characterization and chromotropic properties of MnII, CoII, NiII and CuII with bis (acesulfamato) bis ( 3 -methylpyridine) complexes

The novel 3- [M: Mn^II, Co^II, and Ni^II] and 3- complexes (acs: acesulfamate; 3-pic: 3-methylpyridine) have been synthesized and characterized using elemental analyses, magnetic moments, UV–Vis and FT-IR spectra. The thermal behaviour of the complexes was also studied by simultaneous TG, DTG and DTA methods in static air atmosphere. The chromotropic properties of all complexes have been studied using thermal and spectral analysis. While the complexes of Co^II and Ni^II show reversible continuous thermochromism, an irreversible discontinuous thermochromism is observed in the Mn^II and Cu^II) complexes in the solid state. The observed thermochromism in the Mn^II, Co^II and Ni^II complexes is due to the different ligand field strength associated with the deaquation reaction. The solvatochromic behaviour of the complexes is also studied and all anhydrous complexes (except Mn^II) exhibit solvatochromic properties depending on the donor number of the solvent.     

Synthesis of some new five membered heterocycles,a facile synthesis of oxazolidinones

The synthesis and structural properties of two kinds of thiosemicarbazide derivatives ( 2a‐c and 3a‐c ) and one kind of semicarbazide derivatives ( 4a, 4b ) have been described. These compounds were synthesized by treating 2‐(4‐amino‐3‐alkyl‐5‐oxo‐4,5‐dihydro‐1H‐1,2,4‐triazol‐1‐yl)acetohydrazides ( 1a‐c ) with benzyl isothiocyanate, 3‐florophenyl isothiocyanate and benzylisocyanate, respectively. The synthesis of 4‐amino‐3‐alkyl‐1‐[(4‐alkyl‐5‐mercapto(or 5‐oxo)‐4H‐1,2,4‐triazol‐3‐yl)methyl]‐4,5‐dihydro‐1H‐1,2,4‐triazol‐5‐ones ( 5a‐c, 6a‐c and 7 ) have been performed from the reaction with sodium hydroxide. On the other hand, the acidic treatment of compounds 2b, 3b and 4b has afforded 4‐amino‐3‐(4‐chlorobenzyl)‐1‐[(5‐alkylamino‐1,3,4‐thidazol(or 1,3,4‐oxazol)‐2‐yl)methyl]‐4,5‐dihydro‐1H‐1,2,4‐triazol‐5‐ones ( 8, 9 and 10 ). The condensation of thiosemi(or semi)carbazide derivatives ( 2a‐c, 3c and 4b ) with 4‐chlorophenacylbromide have resulted in the formation of 2‐[4‐amino‐3‐alkyl‐5‐oxo‐4,5‐dihydro‐1H‐1,2,4‐triazol‐1‐yl]‐N′‐(3,4‐dialkyl‐1,3‐thiazol(or oxazol)‐2(3H)‐yliden]acetohydrazides ( 11a‐c, 12, 13 ), while their condensation with chloroacetic acid has produced 2‐[4‐amino‐3‐alkyl‐5‐oxo‐4,5‐dihydro‐1H‐1,2,4‐triazol‐1‐yl]‐N′‐[3‐(3‐alkyl)]‐4‐oxo‐1,3‐thiazolidin(or oxazolidin)‐2‐yliden}acetohydrazides ( 14, 15 and 16 ). The spectral data and elemental analyses have support the proposed structures.