Unsymmetrical Imines Research Articles

Influence of imine symmetry and triphenylamine moieties on photovoltaic properties of BHJ organic solar cells

In this paper the influence of imine symmetry and triphenylamine moieties presence on photovoltaic properties of bulk heterojunction organic solar cells were analysed in details. Three imines: (E)-N-(4-((4-((E)-(benzo[d]thiazol-2-ylimino)methyl)phenyl)(phenyl)amino)benzylidene)benzo[d]thiazol-2-imine (PV-BLJ-SC1),(E)-N-(4-diphenylamino)benzylidene)benzo[d]thiazol-2-imine (PV-BLJ-SC2) and (N,N'E,N,N'E)-N,N'-([2,2′:5′,2′'-terthiophene]-5,5′'-diylbis(methanylylidene))bis(benzo[d]thiazol-2-imine) (PV-BLJ-SC3) were investigated as donor or acceptor components in binary and ternary active layer. Moreover, the influence of admixture (1,8-diiodooctane or diphenyl ether), and presence of poly[(9,9-bis(3′-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9–dioctylfluorene)] as cathode buffer layer on the photovoltaic parameters of the constructed imine-containing solar cells was analysed in details. All the conducted experiments confirmed the possibility of using unsymmetrical imine PV-BLJ-SC2, showing the best results, in organic photovoltaics. The HOMO and LUMO levels of the imines were determined by cyclic voltammetry, showing dependance of on the chemical structure and its symmetry, and for PV-BLJ-SC2 gaved −5.07 eV and −2.23 eV, respectively. In the case of PV-BLJ-SC1 and PV-BLJ-SC2 the electron density of HOMO was mainly located on triphenylamine moieties, while in the case of PV-BLJ-SC3 on thiophene moieties, as it was confirmed by the density functional theory studies. Based on the highest conductivity (9 × 10-8 S/cm2) result for PV-BLJ-SC2, this imine was selected to prepare binary and ternary layers with PTB7 or PTB7:PC71BM and thermal imaging studies were performed. Finally, PV-BLJ-SC2 was introduced to the PTB7:PC71BM binary system, where a power conversion efficiency as high as 4.17% was achieved after the addition of 1,8-diiodooctane. It gaved better result than the reference sample containing PTB7:PC71BM and 1,8-diiodooctane (3.11%). In the case of reference solar cells the addition of 1,8-diiodooctane improved the efficiency of about 22 %, while for solar cells containing also PV-BLJ-SC2 imine the efficiency increased by more than 107 %. Our study presents a quite effective and cheap method to improve the efficiency of organic solar cells by adopting a ternary approach.

Atomically Dispersed Vanadium Sites Anchored on N-Doped Porous Carbon for the Efficient Oxidative Coupling of Amines to Imines.

Single-atom catalysts effectively integrate the respective advantages of homogeneous and heterogeneous catalysts and are a pioneering research frontier in catalysis by virtue of their maximized utility of metal atoms and distinct atomic configuration. However, development of such catalysts is still in the early stages. Herein, atomically dispersed vanadium (V) sites that are coordinated by N atoms and inlaid within N-incorporated porous carbon networks were prepared through a top-down strategy by annealing a V-containing metal-organic framework, NH2-MIL-101(V), followed by acid etching. The resulting V-N-C-600 catalyst exhibits unexpected catalytic reactivity, selectivity, and robust stability for the direct aerobic oxidation of benzylamine to generate N-benzylidene benzylamine with molecular oxygen under mild conditions. The turnover frequency reaches 53.9 h-1, which is much superior to those achieved over the commercial V2O5 and state-of-the-art non-noble metal heterogeneous catalysts reported in the literature. Kinetic analysis reveals a low activation energy barrier (37 kJ mol-1) for the benzylamine oxidation and indicates that a carbocationic intermediate is involved in the reaction mechanism. The synergistic effect between the isolated V single-atomic sites and N-doped hierarchically porous carbon network boosts the performance of V-N-C-600. Moreover, V-N-C-600 exhibits a wide generality for the efficient synthesis of a set of symmetrical imines, unsymmetrical imines, and imine derivatives.

A comprehensive optical and electrical study of unsymmetrical imine with four thiophene rings and their binary and ternary compositions with PTB7 and PC70BM towards organic photovoltaics.

A new unsymmetrical imine with four thiophene rings was synthesized in a one-step reaction, starting from the commercially available and relatively inexpensive reagents. The obtained imine in the form of thin films exhibited photoluminescence properties in the 1.8–2.4 eV energy range and a photoluminescence lifetime of about 0.3 ns. The HOMO and LUMO levels of the imine determined by cyclic voltammetry were at about −5.19 eV and −3.05 eV, respectively. The density functional theory was applied to calculate the geometric and electronic structure of the imine. The UV-Vis spectra showed that the absorption range of the imine overlaps with that of PC70BM, and the absorption peak at the maximum of the imine at 424 nm is located between the two maxima at 404 nm and 461 nm of the fullerene derivative. The electron acceptor and donor activity of the imine was tested in the solar cell architecture: glass/ITO/PEDOT:PSS/active layer/In/Al. The best photovoltaic parameters, with very good reproducibility for each 8 pixels in the cell, were found for the active layer based on ternary mixture PTB7:PC70BM:imine at a weight ratio 8 : 13 : 1, with the power conversion efficiency of about 4%. The external quantum efficiency of devices with the imine was found to be about 40% at 3.3 eV. The thermal imaging together with the recorded current response at increasing potential showed that the presence of imine in the composition has a beneficial impact in terms of current flow stability at temperatures above 200 °C, compared to two component layers with the same imine as an additive.

Electrochemical and optical studies of new symmetrical and unsymmetrical imines with thiazole and thiophene moieties

In this study new symmetrical and unsymmetrical imines based on 4-[4-(4-fluorophenyl)1,3-thiazol-2-yl]aniline and 2,2′,5′,2”-terthiophene-5,5”-dicarboxaldehyde or 2,2’:5′, 2’’-terthiophene-5-carboxaldehyde, respectively, were synthesized by melt condensation with the yield of 86% and 40%. The 5% weight loss of the imines was found in temperature range from 294 to 390 °C in nitrogen, depending on the symmetry of aldehyde used in synthesis. The band gap of symmetrical imine (PV-BLJ-SC13) is lower by about ∼0.33 eV than that of unsymmetrical PV-BLJ-SC14. For both imines the electron density of HOMO level is mainly located on thiophene moieties and is extended to imine bonds in thiazole rings and imine moieties. The theoretical calculations of their HOMO-LUMO levels by DFT methods were also provided. The UV–Vis absorption spectra and cyclic voltammograms of imines both in the form of thin films cast on the electrode as well as dissolved in 1,2-dichloromethane were studied to determine the electrochemical and optical band gap energies as well as correlate the positions of HOMO and LUMO levels obtained by DFT and electrochemical methods. The resistance of imines was approximately 113.8 Ω and 102.4 Ω for PV-BLJ-SC13 and PV-BLJ-SC14, respectively as determined by IR thermal images and have a tendency to decrease by about 17–24 Ω when mixed with PTB7 and PC71BM. Both imines showed very bright luminescence. Moreover, optical absorption, photoluminescence and IR thermal images were measured for imine:PTB7 or imine:PTB7:PC71BM composite. Finally, simple organic solar cells based on (PTB7:imine):PC71BM in weight ratio (4:1):8 and (8:1):13 w/w were constructed and characterized. The highest power conversion efficiency, which was equal to 0.42% was determined for the ITO/PEDOT:PSS/PTB7:PV-BLJ-SC13:PC71BM (4:1):8/Al device. In addition, the power conversion efficiency was strongly dependent on the weight ratio of imine in active layer.

Vanadium catalyzed direct synthesis of imines from amines or alcohols and amines by an aerobic oxidative reaction under mild conditions

The direct synthesis of imines from amines or alcohols and amines by vanadium catalyzed aerobic oxidation was developed. Without an additive or promoter, various symmetrical and unsymmetrical imines were obtained in good to excellent yields under mild conditions with air as an environmentally benign oxidant. The catalyst is very easy to prepare and use, and this catalytic system is also effective for the synthesis of heteroatom-containing imines.

Optical properties of unsymmetrical azomethines with one imine bonds

We have explored the photoluminescence (PL) and electronic properties, that is, orbital energies and resulting energy gap calculated theoretically by density functional theory (DFT) of four unsymmetrical (UAz1–UAz4) azomethines. All of the investigated compounds exhibited mesomorphic behavior. The photoluminescence studies have shown that molecular structure of the imines influenced both the PL properties and HOMO–LUMO levels of azomethines. Azomethines emitted violet, blue or green light. The effect of excitation wavelength and concentration on the PL properties has been detected as well. Unsymmetrical imine UAz3 posses carbazole unit exhibited lower both HOMO and LUMO energies compare to others investigated azomethines. Additionally, azomethines were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Two unsymmetrical imines (UAz2 and UAz3) exhibited irreversible oxidation behavior. The HOMO level of the compound with ethylcarbazole (UAz2) moiety was observed at −5.22eV, while for the UAz3 with phenoxybiphenyl unit was found at −5.64eV. The data obtained by theoretical calculation using DFT method was very similar to the results obtained by electrochemical measurements.

Cobalt (II) and Copper (I) Complexes of Rigid Bidentate [N‐(2, 6‐Diisopropyl‐phenyl)imino]acenapthenone Ligand: Synthesis and Structural Studies

AbstractThe cobalt(II) complex [CoCl2(2, 6‐iPrC6H3‐BIAO)]2 (1) of rigid unsymmetrical imine, carbonyl mixed ligand [N‐(2, 6‐diisopropylphenyl)‐imino]acenapthenone] (2, 6‐iPrC6H3‐BIAO) (L1) can be achieved by the reaction of CoCl2 and neutral [N‐(2, 6‐diisopropylphenyl)‐imino]acenapthenone] ligand. When ligand L1 reacted with CuCl in dichloromethane solution, only nitrogen coordinated copper complex [CuCl(2, 6‐iPrC6H3‐BIAO)] (2) was obtained. In the solid‐state structure, compound 1 is dimeric through the chelating two μ2 chlorine atoms and each cobalt atom adopts either a distorted trigonal bipyramidal or a distorted square pyramidal arrangement. In contrast, the molecular structure of compound 2 reveals that copper is coordinated by imino nitrogen and adopts a linear arrangement around the central metal atom. The crystal structure of the rigid bidentate mixed nitrogen and oxygen ligand (2, 6‐iPrC6H3‐BIAO) (L1) is also reported.

Characterisation and Mesomorphic Behavior of Rod-Shaped Unsymmetrical Imine with a Fluorinated Chain and a Carboxylic Group

The synthesis and thermal properties of unsymmetrical imine with a fluorinated chain and a carboxylic group are described. The mesomorphic behavior was investigated via differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) studies. Additionally, we compared the mesomorphic behavior of the azomethine presented in this work with other azomethines.

Thermotropic and opto(electrical) properties of liquid crystalline imine with two fluorinated chains

The optical, electrical and thermal properties of unsymmetrical imine with two fluorinated chains are described. The structure of imine was characterized by means of 1H, 13C NMR spectroscopy and elemental analyses and the results show an agreement with the proposed structure. The wide-angle X-ray diffraction [WAXD(T)] technique in different temperatures was used to probe the structural properties of the azomethine. Mesomorphic behaviour was investigated via differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) studies. Additionally, the mesomorphic behaviour of the azomethine presented in this work was compared with other azomethines. The absorption (UV-vis), photoluminescence (PL) and thermoluminescence (TL) features of the compound are documented. The sample was irradiated with a test dose of 2 Gy Co-60 gamma rays. Current–voltage (I–V) measurements were performed on an ITO/Az/Al device in the dark and during irradiation with light (under illumination of 1000 W/m 2).

Structure–properties relationship of linear and star-shaped imines with triphenylamine moieties as hole-transporting materials

We have presented 17 solution-processable linear and star-shaped imines with triphenylamine moieties. Six different amines with electron-donating or electron-withdrawing substituents and three aldehydes varying in the number of carbonyl groups have been used to study structure–optical property correlations. The unsymmetrical and symmetrical imines have been examined as a hole-transporting material (p-type) for organic light-emitting diodes (OLED)s. Current–voltage measurements were performed on ITO/compound/Alq 3/Al devices. The lowest optical band gap value was detected at 2.12 eV. The symmetry and shape of the compounds along with the structure of the amines influenced the photoluminescence (PL) properties. Most of the obtained imines emitted blue light. The excitation wavelength and concentration of the imines also affected PL. Relative PL intensity of the imines investigated in chloroform solution was found at the range of 0.15–61% in relation to 9,10-diphenylanthracene. Melting point and glass transition temperature detected via differential scanning calorimetry (DSC) increased in the following order: unsymmetrical imines, symmetrical linear imines and star-shaped ones.

Ru(III), Pd(II), Pt(III), and Pt(IV) Complexes of a Novel 32-Membered Unsymmetrical Dinucleating Macrocyclic Ligand

Reactions of [N12] macrocyclic ligand, L ·2HClO4, with RuCl3, PdCl2, K2[PtCl6], [K2PtCl4] as well as [M(Ph3P)2Cl2] (M = Pd or Pt), and [Ru(Ph3P)3Cl2] produces bimetallic complexes whose analytical data are consistent with the molecular formulae as Ru2LCl4(ClO4)2 (I), Pd2LCl2(ClO4)2 (II), Pt2LCl6(ClO4)2 (III), Pt2LCl2(ClO4)2 (IV) and Ru2LCl2(ClO4)2 (V). Reactions of the ligand with the precursors [M(Ph3P)2Cl2] (M = Pd or Pt), and [Ru(Ph3P)3Cl2], has released all the Ph3P ancillary ligand in solution. Magnetic moment, IR and UV-visible spectroscopic data confirms the encapsulation of metal ions in the macrocyclic cavities through chelation from aza groups of the unsymmetrical imine (─C═N─) and amine (C─NH─C) functions. The macrocyclic moiety has accommodated both the lower as well as higher oxidation states of metal ions, i.e., Ru(II), Ru(III), Pd(II), Pt(II), and Pt(IV), which shows its flexible nature and capability to form stable complexes.

ChemInform Abstract: Synthesis of Biologically Active Benzothiazole Substituted Thiazolidinone Derivatives via Cyclization of Unsymmetrical Imines.

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Synthetic, magnetic, spectral, antimicrobial and antifertility studies of dioxomolybdenum(VI) unsymmetrical imine complexes having a N∩N donor system

Unsymmetrical imine molybdenum(VI) complexes of the type [MoO2(L1)(L2)] formed by the interaction of dioxobis(2,4-pentanedionato)molybdenum(VI) in a 1:1:1 molar ratio with different imines derived from the reactions of sulphagunanidine, sulphamethazine, sulphapyridine and sulphadiazine with various aromatic aldehydes and ketones, have been prepared and the products characterized by elemental analysis, molar conductance, magnetic measurements and spectral studies. The complexes have also been tested in vitro. The antifertility screening data indicate the antiandrogenic nature of the complexes. The spectral studies suggest that all the ligands behave in a bidentate fashion, coordinating through the azomethine nitrogen (>C=N−) and other functional group NH as (N∩N) donors. Studies also reveal that the ligands react with dioxobis(2,4-pentanedionato)molybdenum(VI) to give diamagnetic mononuclear molybdenum(VI) complexes.

Spectral and biological properties of unsymmetrical imine complexes of dioxomolybdenum(VI) with sulfadrug azomethines and thiosemicarbazone

A few unsymmetrical imine dioxomolybdenum(VI) complexes of the type MoO 2 (L)(L') with thiophene thiosemicarbazone (LH) and sulfadrugs azomethines (L'H) have been synthesized in 1 : 1 : 1 molar ratio. The ligands are foundto be monobasic bidenlate and the complexes are diamagnetic. The ligands and the metal complexes have been screened against several bacteria and fungi.

Remarkably high regioselective deprotonation and alkylation of unsymmetrical imines at the more substituted .alpha.-carbon atom

Remarkably high regioselective deprotonation and alkylation of unsymmetrical imines at the more substituted .alpha.-carbon atom