Synthesis and characterization of fluorene-carbazole and fluorene-phenothiazine copolymers with carbazole and oxadiazole pendants for organic light emitting diodes

We report the synthesis and characterization of new series of the fluorene based polymers with carbazole and oxadiazole pendants for the generation of the white emission out of the EL device. In the fluorene backbone, hole transporting units such as carbazole or phenothiazine were incorporated to improve the EL brightness and efficiency. The PFCzOxd-co-PCzs and PFCzOxd-co-PPTZs in EL spectra showed maximum peaks at around 430 nm and additional large peaks at around 530 and 500 nm, respectively. In case of PFCzOxd-alt-PCz and PFCzCzPCz-co-PFOxdOxdPCz, the EL spectra of the polymers showed two distinct peaks comprising the maximum at 427 nm, which corresponds to the EL spectra of the conjugated backbone, and additional broad peaks at around 540 and 530 nm, respectively. The CIE coordinates of the devices from PFCzOxd-alt-PCz and PFCzCzPCz-co-PFOxdOxdPCz were (0.28, 0.33) and (0.25, 0.32), respectively, approaching the value of the standard white of National Television System Committee (NTSC) (0.33, 0.33).     

Diaminofuroxan: Synthetic Approaches and Computer‐Aided Study of Thermodynamic Stability

Different approaches to synthesize diaminofuroxan are presented herein. Mathematical and quantum chemical methods were used to study the possible reasons for failures in the syntheses of diaminofuroxan. Additionally, structural isomers of this compound were generated. With the help of the results of quantum chemical calculations at levels of DFT B3LYP 6‐31G(d) and MP2 6‐31G(d), screening of the most stable isomeric forms in the gaseous phase and in water was performed. It was shown that diaminofuroxan is not the thermodynamically most stable isomer among its structural analogues.     

Substituted Thiadiazole, Oxadiazole, Triazole and Triazinone as Antimicrobial and Surface Activity Compounds

Stearic acid ( 1 ) was utilized as a new cheap starting material in the manufacture of important biologically active heterocycles as thiadiazole, oxadiazole, triazole and triazinone derivatives ( 2 – 11 ) by treating with different nucleophiles. These heterocycles bears active hydrogen atom (SH, NH and NH₂) which could be propoxylated by different moles of propylene oxide (5, 10, 15 mol) to produce nonionic compounds ( 12 – 21 ) a – c having functions as surface and antimicrobial activities. The structural elucidation of these compounds is based on IR, ¹H NMR, ¹³C NMR and elemental analysis. The surface properties (surface and interfacial tension, cloud point, witting time, foaming properties and emulsion stability) and the biodegradability were screened beside these compounds have been tested for their antimicrobial activity.     

2,5-Bis(n-methoxyphenyl)-1,3,4-oxadiazoles used as corrosion inhibitors in acidic media: correlation between inhibition efficiency and chemical structure

The efficiency of 2,5-bis(n-methoxyphenyl)-1,3,4-oxadiazoles (n-MOX), as corrosion inhibitors for mild steel in 1 M HCl and 0.5 M H₂SO₄ have been determined by weight loss measurements and electrochemical studies. The results showed that these inhibitors revealed a good corrosion inhibition even at very low concentrations. Comparison of results among those obtained by the studied oxadiazoles showed that 2-MOX was the best inhibitor. It is found to behave better in 1 M HCl than in 0.5 M H₂SO₄. Polarisation curves indicate that 2-MOX is a mixed inhibitor in 1 M HCl, but in 0.5 M H₂SO₄, the inhibition mode of 2-MOX depends on the electrode potential and acts essentially as a cathodic inhibitor. The inhibition efficiency slightly increases with temperature in the range from 25 to 60 °C, the associated activation energy have been determined. The addition of 2-MOX leads to decrease this activation energy. The adsorption of 2-MOX on the mild steel surface in both acidic media follows a Langmuir isotherm model. Significant correlations are obtained between inhibition efficiency with the calculated chemical indexes, indicating that variation of inhibition with structure of the inhibitors may be explained in terms of electronic properties.     

Nanosecond laser operation by spectroscopical parameters of the oxadiazole derivatives

We have studied the variation of principal spectroscopic parameters (absorption edge, spectral positions of the first three principal bands, oscillator strengths) for three oxadiazoles (pyrazoloquinoline derivatives) with different state dipole moments incorporated into the polymethyl methacrylate (PMMA) polymer matrices in the 3% in weighting units. For investigations we have chosen three derivatives with different values of the state dipole moments. We have found that during illumination by 10 ns Nd-YAG laser beam with pulse duration about 10 ns, frequency repetition about 10 Hz and power density about 0.8–1.3 MW cm⁻² the observed photoinduced changes red shifted for the three principal spectral bands situated at 330–350 nm; 450–500 nm and 525–550 nm. It was established that under influence of the pulsed Nd-YAG laser we observe substantial spectral shifts of the observed spectral maxima. The value of the shift is increased with decreased state dipole moment values.     

Improved electroluminescence efficiency of polyfluorenes by simultaneously incorporating dibenzothiophene-S,S-dioxide unit in main chain and oxadiazole moiety in side chain

A series of efficient and spectrally stable blue light-emitting polyfluorene derivatives containing 3,7-dibenzothiophene-S,S-dioxide (SO) unit in main chain and oxadiazole (OXD) moiety in the side chain were synthesized via Suzuki copolymerization. It was realized that the glass transition temperatures of the resulted copolymers PFSO-OXD increased gradually with the content of OXD, while the UV-vis absorption, photoluminescence spectra, as well as electrochemical properties were not significantly influenced by the molar ratio of OXD unit. Apparent solvatochromism of copolymers PFSO-OXD can be realized by varying polarity of solvents from toluene to dichloromethane. Light-emitting devices based on PFSO-OXD exhibited superior performances to those of PFSO and PF-OXD20 due to the more balanced charge carrier mobility of the devices. The electroluminescence spectra of all copolymers are independent with the current densities and thermal annealing. The best device performance was achieved based on PFSO-OXD20 with a maximal luminous efficiency of 4.9 cd A⁻¹ with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.16, 0.12). The results indicated that the strategy of concurrently incorporating SO and OXD unit into the main chain and side chain of polyfluorenes, respectively has great potential to achieve efficient blue light-emitting polymers.     

Synthesis and electrochemical characterization of a new polymer constituted of alternating carbazole and oxadiazole moieties

We report herein the synthesis and electrochemical characterization of a novel copolymer containing an electron rich carbazole moiety and an electron deficient oxadiazole unit—poly[N-(2′-ethylhexyl)-carbazole-3,6-diyl-1″,3″,4″-oxadiazole-2″,5″-diyl] (PCO). PCO can be dissolved in THF, CHCl₃, xylene, and DMSO. The structure of the polymer is confirmed by FT-IR, NMR and elemental analysis. The optical and electronic properties of the polymer are investigated by UV–Vis absorption spectroscopy and photoluminescence spectroscopy as well as cyclic voltammetry. The results show that the polymer films emit greenish-blue light (λ_max 485 nm) upon UV excitation. Both p-doping and n-doping processes are observed in cyclic voltammetric investigation. A comparison between the properties of polycarbazole and polycarbazole–oxadiazole has been presented.     

新型有机电致发光材料

本文介绍新型的适合制造有机电致发光板新材料：一氧二氮杂茂系列材料，硅醚系列材料和稀土金属络合物系列材料，同时也介绍了它们的特性     

2,5-Bis(4-dimethylaminophenyl)-1,3,4-oxadiazole and 2,5-bis(4-dimethylaminophenyl)-1,3,4-thiadiazole as corrosion inhibitors for mild steel in acidic media

2,5-Bis(4-dimethylaminophenyl)-1,3,4-oxadiazole (DAPO) and 2,5-bis(4-dimethylaminophenyl)-1,3,4-thiadiazole (DAPT) have been synthesised and their inhibiting action on the corrosion of mild steel in 1 M HCl and 0.5 M H₂SO₄ at 30 °C has been investigated by various corrosion monitoring techniques. At constant acid concentration, the inhibitor efficiency of both the compounds is found to increase with inhibitor concentration. DAPT is slightly more efficient in 0.5 M H₂SO₄ than in 1 M HCl whereas DAPO is more efficient in 1 M HCl. Of the two, DAPT appears to be a better inhibitor. Potentiostatic polarisation studies show that both are mixed-type inhibitors in 1 M HCl but cathodic-type in 0.5 M H₂SO₄. The inhibitors function through adsorption following Langmuir isotherm in both the acids. The electronic properties of DAPO and DAPT, obtained using the AM1 semi-empirical quantum chemical approach, have been correlated with their experimental inhibition efficiencies using the linear resistance model (LR). These inhibitors are considered as a non-cytotoxic substances.     

Corrosion inhibitors : Part II: Quantum chemical studies on the corrosion inhibitions of steel in acidic medium by some triazole, oxadiazole and thiadiazole derivatives

The corrosion inhibition efficiencies of some triazole, oxadiazole and thiadiazole derivatives for steel in presence of acidic medium have been studied by using AM1, PM3, MINDO/3 and MNDO semi-empirical SCF molecular orbital methods. Geometric structures, total negative charge on the molecule (TNC), highest occupied molecular energy level (E_HOMO), lowest unoccupied molecular energy level (E_LUMO), core-core repulsion (CCR), dipole moment (μ) and linear solvation energy terms, molecular volume (V_i) and dipolar-polarization (π^*), were correlated to corrosion inhibition efficiency. Four equations were proposed to calculate corrosion inhibition efficiency. The agreement with the experimental data was found to be satisfactory; the standard deviations between the calculated and experimental results ranged between ±0.03 and ±4.18. The inhibition efficiency was closely related to orbital energies (E_HOMO and E_LUMO) and μ. The correlation between quantum parameters and experimental inhibition efficiency has been validated by single point calculations for the semi-empirical AM1 structures using B3LYP/6-31G^** as a higher level of theory. The proposed equations were applied to predict the corrosion inhibition efficiency of some related structures to select molecules of possible activity from a presumable library of compounds.