Synthesis and characterization of coumarin thiazole derivative 2-(2-amino-1,3-thiazol-4-yl)-3H-benzo[f]chromen-3-one with anti-microbial activity and its potential application in antimicrobial polyurethane coating

Coumarin, thiazole and their respective derivative products are some of the oldest and most commonly known class of nitrogen and sulphur containing compounds. In recent years there has been considerable interest in this coumarin–thiazole derivatives, which have been reported to exhibit significant biological activity and are widely used as pharmaceuticals. They are capable of imparting anti-microbial activity properties when incorporated into polymers and polymer composites. In this research, coumarin–thiazole derivative 2-(2-amino-1,3-thiazol-4-yl)-3H benzo[f]chromen-3-one (compound III), was prepared and its structure was confirmed by means of its spectra data. It was also screened for its anti-microbial activity against eight different micro-organisms when physically incorporated into a polyurethane varnish formula. Experimental coatings were manufactured on a laboratory scale and applied by means of a brush on both glass and steel panels. The results of the biological activity indicated that the polyurethane varnishes containing the 2-(2-amino-1,3-thiazol-4-yl)-3H-benzo[f]chromen-3-one (compound III) derivative, exhibit a very good antimicrobial effect. The molecular modeling study revealed that it is biologically safe, it is active and it fulfills Lipinski's rule of five. The physical and mechanical resistances of the polyurethane varnish formulations were also studied to evaluate any drawbacks associated with the addition of the derivative. The studies indicate that the physical incorporation of compound III actually enhances slightly both the physical and mechanical properties.     

The effect of intermolecular interactions on the charge transport properties of thiazole/thiophene-based oligomers with trifluoromethylphenyl

A fundamental understanding of the relationship between intermolecular interactions and transport properties in organic semiconducting materials is significant for their potential applications as electronic device element. Carrier transport properties of thiazole/thiophene-based oligomers with trifluoromethylphenyl groups 1, 2, and 3, in which the type and strength of the intermolecular interactions are different, were investigated within the framework of band model. The results show that π–π stacking interactions are mainly responsible for the hole transport, while hydrogen bonding interactions have a great influence on the electron transport. The specific transport mechanism could be explained by analyzing the density of states (DOS) and Γ point wave functions.     

Thermodynamic study of the dimerization equilibrium of methylene blue, methylene green and thiazole orange at various surfactant concentrations and different ionic strengths and in mixed solvents by spectral titration and chemometric analysis

The monomer-dimer equilibrium and thermodynamics of ionic dyes were investigated by spectrophotometric and chemometric methods. The dimerization constants of methylene blue, methylene green and thiazole orange have been determined by studying the dependence of their absorption spectra at different concentrations of surfactants, ionic strengths and mixed solvents by means of UV-visible spectroscopy in aqueous solutions. The processing of the data, performed for the quantitative analysis of pure spectral profiles, was based on the simultaneous resolution of the overlapping bands in the whole set of absorption spectra. Utilizing the van’t Hoff relationship, which describes the dependence of the equilibrium constant on temperature, as a constraint we determined the spectral responses of the monomer and dimer species as well as the enthalpy and entropy of the dimerization equilibrium. The exciton theory was used for the elucidation of the angle between the monomer units and the interaction energy between the molecules of the dimers.     

New azodisperse dyes with thiazole, thiophene, pyridone and pyrazolone moiety for dyeing polyester fabrics

New antipyrinylazo dyes were prepared by diazocoupling of 4-antipyrinyl diazonium chloride with a variety of coupling components e.g. thiazole, thiophene, pyridone, and pyrazole moieties. The synthesized dyes were characterized by UV-visible absorption, IR, ¹H NMR, and MS spectroscopy. These dyes were applied as disperse dyes for dyeing polyester fabrics and their fastness properties were evaluated. Also the position of color in CIELAB coordinates (L*, a*, b*, H*, C*) was assessed.     

Photomodulation of the proton affinity and acid gated photochromism of a novel dimethylaminophenyl thiazole diarylethene

The acid-gated photochromism and the photomodulation of fluorescence and proton affinity of a novel dimethylaminophenyl thiazole diarylethene in MeCN were investigated from a kinetic point of view. Photomodulation of the proton affinities has been estimated from acid titrations and numerical modelling of the acid induced T-photochromism. The basicities of the thiazole and dimethylamino protonation sites are different by only one pK unit. Upon ring- closure, their relative proton affinities are reversed. Our investigations underline the role of the thiazole protonation in the carbon-carbon bond weakening of the closed form and validate the role of the proton as catalyst in the gated T-photochromism.     

Novel 4H-pyranylidene organic dyes for dye-sensitized solar cells: Effect of different heteroaromatic rings on the photovoltaic properties

Eight novel Ruthenium-free dyes consisting of a 4H-pyranylidene donor, a 2-cyanoacrylic acid acceptor and several heterocyclic rings with different electronic properties are designed and synthesized. The photovoltaic performances of the related dye-sensitized solar cells are discussed and compared, obtaining the best results with the thiophene followed by the mismatched-oriented thiazole. Dyes containing a pyrrol or a matched-oriented thiazole lead to the lower efficiencies of all the series. Charge extraction (CE) and transient photovoltage (TPV) measurements were conducted in order to investigate the recombination resistance and the difference in voltage for the devices. In order to get further insight in the electronic and optical properties of the studied compounds, theoretical calculations using TD-DFT and the CPCM have been carried out.     

Synthesis and characterization of novel diazenes bearing pyrrole, thiophene and thiazole heterocycles as efficient photochromic and nonlinear optical (NLO) materials

Two series of novel thermally stable second-order nonlinear optical (NLO) and photochromic chromophores have been designed and synthesized. The two series of compounds were based on different combinations of donor groups (pyrrole or thienylpyrrole) which act simultaneously as π-conjugated bridges, together with diazoaryl or diazothiazolyl as acceptor moieties. Their photochromic and electrochemical behavior were characterized, while hyper-Rayleigh scattering (HRS) was employed to evaluate their second-order nonlinear optical properties. The results of these studies have been critically analyzed together with two other related compounds reported earlier from our laboratories in which the thienylpyrrole system was used as the donor group keeping the functionalized diazoaryl as acceptor moiety. The measured molecular first hyperpolarizabilities and the observed photochromic behavior showed strong variations for the different donor systems used (pyrrole or thienylpyrrole) and were also sensitive to the acceptor strength of the diazenehetero(aryl) moiety.The thienylpyrrole based compounds endowed with extended π-conjugated bridges and stronger donor auxiliary effects in comparison to the pyrrole compounds, when coupled to the stronger acceptor diazo(hetero)aryl groups gave rise to significantly larger hyperpolarizabilities (β = 274-415 × 10⁻³⁰ esu) for an incident wavelength of 1064 nm. These compounds also displayed improved photochromic behavior with very fast response to the visible light stimulus (1.5 s) and fast thermal return to the original forms (2-3 s).     

Synthesis and characterization of triphenylamine flanked thiazole-based small molecules for high performance solution processed organic solar cells

Two new small molecules, 5,5-bis(2-triphenylamino-3-decylthiophen-2-yl)-2,2-bithiazole (M1) and 2,5-bis(2-triphenylamino-3-decylthiophen-2-yl)thiazolo[5,4-d]thiazole (M2) based on an electron-donor triphenylamine unit and electron-acceptor thiophene-thiazolothiazole or thiophene-bithiazole units were synthesized by a palladium(0)-catalyzed Suzuki coupling reaction and examined as donor materials for application in organic solar cells. The small molecules had an absorption band in the range of 300-560 nm, with an optical band gap of 2.22 and 2.25 for M1 and M2, respectively_. As determined by cyclic voltammetry, the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels of M1 were −5.27 eV and −3.05 eV, respectively, which were 0.05 eV and 0.02 eV greater than that of M2. Photovoltaic properties of the small molecules were investigated by constructing bulk-heterojunction organic solar cell (OSC) devices using M1 and M2 as donors and fullerene derivatives, 6,6-phenyl-C61-butyric acid methyl ester (PC₆₁BM) and 6,6-phenyl-C71-butyric acid methyl ester (PC₇₁BM) as acceptors with the device architecture ITO/PEDOT:PSS/M1 or M2:PCBM/LiF/Al. The effect of the small molecule/fullerene weight ratio, active layer thickness, and processing solvent were carefully investigated to improve the performance of the OSCs. Under AM 1.5 G 100 mW/cm² illumination, the optimized OSC device with M1 and PC₇₁BM at a weight ratio of 1:3 delivered a power conversion efficiency (PCE) of 1.30%, with a short circuit current of 4.63 mA/cm², an open circuit voltage of 0.97 V, and a fill factor of 0.29. In contrast, M2 produced a better performance under identical device conditions. A PCE as high as 2.39% was recorded, with a short circuit current of 6.49 mA/cm², an open circuit voltage of 0.94 V, and a fill factor of 0.39.     

Triazole and thiazole derivatives as corrosion inhibitors for AA2024 aluminium alloy

The 1,2,4-triazole, 3-amino-1,2,4-triazole, benzotriazole and 2-mercaptobenzothiazole were evaluated in the present work as corrosion inhibitors for protection of the 2024 aluminium alloy in neutral chloride solutions. The corrosion protection performance was investigated by means of DC polarization and electrochemical impedance spectroscopy (EIS). Scanning Kelvin probe force microscopy (SKPFM) and atomic force microscopy (AFM) were used to study the evolution of the Volta potential distribution and the surface topography during corrosion tests.The results show that all inhibitors under study confer corrosion protection to the AA2024 alloy forming a thin organic layer on the substrate surface. Benzotriazole and 2-mercaptobenzothiazole offer better corrosion protection in comparison with the other two. The inhibitors studied act decreasing the rate of both the anodic and cathodic processes. In the latter case the dealloying of the copper-reach particles is hindered, slowing down the oxygen reduction.     

5-卤代-2-(4-芳基-噻唑-2-基)-腙甲基-苯酚的合成

以5-卤代-水杨醛为原料,与氨基硫脲发生缩合反应,生成5-卤代-水杨醛缩氨基硫脲。然后分别与ω-溴代苯乙酮、对甲氧基-ω-溴代苯乙酮在甲醇或丙酮溶剂中回流反应10 min,得到6个5-卤代-2-(4-芳基-噻唑-2-基)-腙甲基-苯酚,最后通过红外、核磁、质谱对其进行了结构表征。