Organic–inorganic hybrids based on liquid crystalline symmetrical imine (8Z)-N-(4-((Z)-(4-pentylphenylimino)methyl)benzylidene)-4-pentylbenzenamine (AZJ1) with two aliphatic chains and TiO2 nanomaterials were obtained and investigated taking into account thr crystallographic form of titanium dioxide i.e. anatase versus rutile. The type of TiO2 influences the mesomorphic properties of imine AZJ1, as observed by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) techniques. Fourier-Transform Infrared Spectroscopy (FT-IR) was used to investigate the interactions of oxygen vacancies located on the TiO2 surface with the studied AZJ1 imine together with studying the influence of temperature. Both imine:TiO2 anatase versus rutile hybrids possessed the highest occupied molecular orbital (HOMO) levels of about −5.39 eV (AZJ1:anatase) and −5.33 eV (AZJ1:rutile) and the lowest unoccupied molecular orbital (LUMO) levels of about −2.24 eV. The presence of TiO2 in each hybrid did not strongly affect the redox properties of imine AZJ1. Organic devices with the configuration of ITO/TiO2/AZJ1 (or AZJ1:TiO2 anatase versus rutile)/Au were fabricated and investigated in the presence and absence of visible light irradiation with a light intensity of 93 mW/cm2. Finally, to analyze defects in the constructed organic devices we used thermal imaging and atomic force microscopy (AFM). The addition of TiO2 in both crystallographic forms has a positive influence on layer-forming properties that manifests itself as a very homogenous heat distribution for the whole sample.
Three (4,4'-((1E,1'E)-(2,5-bis(octyloxy)-1,4-phenylene)bis(ethene-2,1-diyl))bis-(E)-N-(2,5-bis(octyloxy)benzylidene)) imine derivatives were synthesized via a condensation reaction with p-toluenesulfonic acid as a catalyst. The effects of the end groups and vinylene (-HC[double bond, length as m-dash]CH-) moieties on the structural, thermal, optical, electrochemical and photovoltaic properties of imines were investigated to check the influence of TiO2 on the imine properties. The thermal behavior of imines and their complexes with TiO2 was widely investigated using FT-IR, XRD, DSC and POM methods in order to determine the order type in the imine structure. All imines present the highest occupied molecular orbital (HOMO) levels of about -5.39 eV (SAI1 and SAI2) and -5.27 eV (SAI3) and the lowest unoccupied molecular orbital (LUMO) levels at about -3.17 eV. The difference of the end groups in the imines in each case did not affect redox properties. Generally, both oxidation and reduction are easier after TiO2 addition and it also changes the HOMO-LUMO levels of imines. Moreover, changes in the characteristic bands for imines in the region 1500-1700 cm-1 observed as a drastic decrease of intensity or even disappearance of bands in the imine : TiO2 mixture suggest the formation of a complex (C[double bond, length as m-dash]N)-TiO2. Organic devices with the configuration of ITO/TiO2/SAIx (or SAIx : TiO2)/Au were fabricated and investigated in the presence and absence of visible light irradiation with an intensity of 93 mW cm-2. In all imines and complexes with TiO2, the generation of the photocurrent indicates their use as photodiodes and the best result was observed for SAI3 : TiO2 complexes.
A mixture of aldehyde (1.0 mmol) and amine (2.5 mmol) in N,N-dimethylacetamide (DMA) solution in the presence of p-toluenesulfonic acid (PTS) (0.06 g) was refluxed with stirring for 10 hours. The reaction was conducted in an argon atmosphere and the condenser was fitted with a Dean-Stark trap. After cooling, the mixture was precipitated with 100 ml of ethanol. The crude
The effect of the presence of titanium dioxide in two new imines, (E,E)-(butane-1,4-diyl)bis(oxybutane-4,1-diyl) bis(4-{[(benzo[d][1,3]thiazol-2-yl)methylidene]amino}benzoate) (SP1) and (E)-N-[(benzo[d][1,3]thiazol-2-yl)methylidene]-4-dodecylaniline (SP2), on the properties and stability of imine:TiO2 composites for organic device applications were examined. The investigated titanium dioxide (in anatase form, obtained via the sol–gel method) exhibited a surface area of 59.5 m2/g according to Brunauer–Emmett–Teller theory, and its structure is a combination of both meso- and microporous. The average pore diameter calculated by the Barrett–Joyner–Halenda method was 6.2 nm and the cumulative volume of pores was 0.117 m3/g. The imine SP1 exhibited columnar organization (Col), while SP2 revealed a hexagonal columnar crystalline phase (Colhk). The imine:TiO2 mixtures in various weight ratio (3:0, 3:1, 3:2, 3:3) showed a lower energy gap and HOMO–LUMO energy levels compared to pure TiO2. This implies that TiO2 provides not only a larger surface area for sensitizer adsorption and good electron collection, but also causes a shift of the imine energy levels resulting from intermolecular interaction. Also the temperature of the phase transition was slightly affected with the increase of TiO2 concentration in imine-based composites. The changes observed in the Fourier transform middle-infrared absorption (FT-MIR) spectra confirmed the significant influence of TiO2 on structural properties of both investigated imines. Similar interactions of oxygen vacancies existing on the TiO2 surface with SP1 and SP2 were observed. The imine:TiO2 mixtures showed good air stability and reusability, which demonstrates its potential for organic device applications.
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