Acac Research Articles

Synthesis of New Furanone Derivatives with Potent Anticancer Activity

New compounds based on Furanone derivatives were synthesized by reaction of 3-(4-nitrobezylidine)-5-phenylfuran-2(3H)-one with various reagents as malononitrile then D-glucose, thiosemicarbazide then D-glucose, ethyl acetoacetate, acetyl acetone, ethyl cyanoacetate, hydrazine hydrate/acetic acid, thiourea, o-phenylene diamine, hydrazine hydrate/ethanol then 2-naphthalene thionylchloride and/or thiourea. Also, 3-(4-nitrobezylidine)-5-phenylfuran-2(3H)-one was reacted with benzyl amine to afford the 1,3-dihydro-2H-pyrrol-2-one derivative which was reacted with hydroxyl amine and/or phenyl hydrazine to afford compounds the oxazole and/or pyrazole derivatives respectively. Finely, 6-(4-nitrophenyl)-5-(2-oxo-2-phenylethyl)-2-thioxotetrahydro-pyrimidin-4(1H)-one was allowed to react with 2-oxo-N-phenylpropanehydrazonoyl chloride yielding [1,2,4]triazolo[4,3-a]pyrimidin-7(1H)-one derivative. The anti-cancer activity of some of some of the new synthesized compounds towards breast carcinoma cells (MCF-7) was evaluated that demonstrated good to moderate results. Also, we had evaluated the cytotoxicity of the new tested compounds against the normal cells (MRC-5) which showed low toxicity on them.

Orthoamide und Iminiumsalze, CI. Umsetzungen von N,N,N′,N′-Tetramethylharnstoffdiethylacetal mit CH2-aciden Verbindungen

Abstract N,N,N′,N′-Tetramethylurea diethylacetal reacts with CH2-acidic compounds as benzylcyanide, cyanoacetic acid derivatives malonodinitrile and nitromethane to give ketene aminals or ketene-O,N-acetales. Low polar solvents favour mostly the formation of ketenaminals. The yields of ketenaminals and ketene-O,N-acetals can be improved in some cases by addition of trimethylsilyldimethylamine. The reactions of the urea acetal with diethylmalonate, ore acetyl acetone, stops at the stage of the N,N′,N″-permethylated guanidinium salts with carbanionic counterions. The formation of bis(dimethylamino)methylene-diethylmalonate from the urea acetal and diethylmalonate can be initiated by addition of trimethylsilyldimethylamine/trimethylsilylcyanide. N,N,N′,N′,N″,N″-Hexamethylguanidinium cyanide is formed in the analogous reactions of the urea acetal with N,N-dimethylcyanacetamide or diethylsuccinate. The N,N′,N″-Hexamethyl-guanidinium nitrite can be obtained from the urea acetal and nitropropane.

Synthesis, physicochemical and vibrational spectral properties of 2–pyridone and 2–aminopyridine derivatives: An experimental and theoretical study

A convenient and efficient one–pot three–component reaction of acetyl acetone, malononitrile and ammonium acetate was investigated for the synthesis of 3–cyano–4,6–dimethyl–2–pyridone (PI) and 2–amino–3–cyano–4,6–dimethylpyridine (PII). The products were achieved with high purity, high yields and short reaction time. The yields of the two products depend on the concentration of ammonium acetate, reaction time and the solvent used. The structures of the isolated products were confirmed by elemental analysis and spectral data, supported by quantum chemical (MP2) calculations, both in gas phase and solvents (water and ethanol), that were also employed to track the reaction mechanisms and model vibrational spectral properties for final characterization and interpretation of spectral data. A remarkable matching between theoretical predictions and experiments was attained both for the geometrical parameters, as compared to X-Ray data available in the literature, and for vibrational frequencies, leading to a correlation coefficient (R2) of 0.99. Molecular docking was further studied to predict the docking binding energy of the synthesized compounds with the target proteins.

Surface and photocatalytic properties of TiO2 thin films prepared by non-aqueous surfactant assisted sol-gel method

Titanium dioxide (TiO2) thin films are prepared on glass substrates using sol-gel spin coating method. Titanium tetraisopropoxide (TTIP) precursor is used to prepare TiO2 sol-gels using Ethanol solvent. Acetyl acetone (AcAc) and Acetic acid (AA) are used as modifiers and Cetyltrimethylammonium Bromide (CTAB) surfactant as pore-forming agent. A clear transparent TiO2 sol-gel is obtained without precipitation only when both AA and AcAc are present in the TiO2 sol. A worm-like structure is observed in the film at 0.1 M TTIP and changed to the flake-like structure in the film at 0.4 M TTIP. The TiO2 thin films are non-porous and porous when CTAB is below and above the concentration of 0.8 g per 0.01 mol TTIP. The critical micelle concentrationis found to exist between 0.6 to 0.8 g CTAB per 0.01 mol TTIP. Grazing Incidence X-ray diffraction and Raman analysis confirm the presence of anatase phase in the 3 and 4 times coated TiO2 thin films. The field emission scanning electron microscopy analysis shows that a highly homogeneous and uniform thin film is obtained with TiO2 sol-gel composition of 0.2 M TTIP, 0.1 M AcAc, 0.09 M AA and 1 g of CTAB per 0.01 mol TTIP. The photocatalytic activity of the TiO2 films is determined by investigating the photodegradation of methylene blue (MB) in aqueous solution. The TiO2 thin film with 110.7 nm and 145.3 nm thickness showed 42.6 % and 58.4 % degradation of MB, respectively, at 60 min of photocatalytic reaction under UV light irradiation.

Nanostructured titanium dioxide coatings prepared by Aerosol Assisted Chemical Vapour Deposition (AACVD)

Titanium dioxide is a compound of great interest, due to its functional properties; one of its most important uses is as a photocatalyst. TiO2 coatings can be deposited using different techniques. Aerosol Assisted Chemical Vapour Deposition (AACVD) is particularly interesting, as high temperature or pressure are not necessary to generate the gaseous precursors. Furthermore, by carefully choosing the deposition conditions (i.e. deposition temperature, solvent), it is possible to obtain deposits with different morphology and, consequently, different functional properties. In this paper we present the synthesis of titanium dioxide coatings with AACVD using complexes between titanium isopropoxide (TIPP) and acetyl acetone (acac) as precursors. Deposition experiments were performed using different ratios of TIPP to acac, to assess the effect on the composition of the coatings, their morphology and photocatalytic activity. Results showed that the use of acac led to nanostructured titanium dioxide (nanoparticles of about 10−25 nm diameter). Raman analysis showed the presence of both anatase and rutile phases. XPS analysis indicated the presence of residual carbonaceous species in the coatings; despite this, they displayed photocatalytic properties similar or superior to AACVD films without carbon. Photocatalytic tests, performed measuring the Formal Quantum Efficiency (FQE) and the Formal Quantum Yield (FQY) in the degradation of resazurin, showed that a acac:TIPP ratio equal to 1 led to the material with the highest performance, as the FQE value was about three times higher than that for the coating prepared with TIPP alone. Overall the complexes between TIPP and acac are promising precursors for the AACVD technique, leading to nanostructured coatings with enhanced performance.

Role of complexation in the photochemical reduction of chromate by acetylacetone

Organic ligands can alter the redox behavior of metal species through the generation of metal-ligand complexes. Photo-induced complexation between ligands and metals is an important, but under-appreciated, aspect of process. Acetylacetone (AA) is a good chelating agent due to keto-enol tautomerization. In the presence of AA, photoreduction of Cr(VI) is accelerated; however, it is unclear exactly how complexation is involved in UV/AA mediated Cr(VI) reduction. On the basis of spectral and kinetic analyses, this study shows that the formation of {Cr(VI)-AA}* complexes is the main mechanism of Cr(VI) reduction by UV/AA. Evidence for this includes (1) the formation rate constant of Cr(III)-AA complexes in the UV system was 2–3 orders of magnitude greater than that in the thermal system; (2) there was a linear relationship between the photons absorbed by AA and the reduction rate constants of Cr(VI); and (3) the reaction appeared initially zero-order in Cr(VI) and turned to first-order as the pool of available Cr(VI) ran out. The results presented here are not only important for the better understanding of the complexation effects in the reduction of Cr(VI), but also crucial for the possible application of the UV/AA process in many other scenarios.

Cyclization of thiosemicarbazide derivative: As a source of novel synthesis of some azoles and azines

AbstractIn our study, we aimed to synthesize novel, some biologically active compounds, Azoles and Azines derivatives, that to be nitrogen‐containing heterocycles, and have their diverse therapeutic values. Thiosemicarbazide, 2, was obtained from the attack of nitrogen of hydrazine to the carbon of heteroallene function of compound 1. Triazolotriazole derivative, 4, was obtained from the reaction of 2 with diethyl malonate. Cyclization of thiourea unit of compound 2 with heteroallene, 1, gave trazine, 6. Benzolyation of 2 using benzoyl chloride formed triazole derivative, 8. Reaction of 2 and maleic anhydride gave furothiadazine, 10. Cyclohexanopyrimidinthione, 12, was obtained from cyclocondensation of cyclohexanone with 2. Triazole, 14, was obtained from 2 and ammonium isothiocynate under thermal condition. Reaction of 2 with ethyl bromoacetate gave thiazole derivative, 16. [2+3] Cyclocondensation of acetyl acetone with 2 provided pyrazole, 18. Triazolotriazole, 20, was obtained from formalin and 2. Compound 2 suffers intramolecular base mediated cyclization affording pyrazole, 21. Keeping 2 and propinaldehyde under reflux provided triazolotriazole, 24. Acylation of 2 by succinic acid formed pyridazine derivative, 27.

Nickel(II) Phosphane‐ and N‐heterocyclic Carbene Complexes with Tridentate, Dianionic [S,N,O]2– Ligands

Square‐planar dinuclear nickel(II) complexes containing [S,N,O]2– ligands formed by condensation of acetyl acetone or benzoyl acetone with cysteamine were prepared. These dimeric nickel(II) compounds undergo bridge‐cleavage reactions with the cage phosphine PTA (PTA = 1,3,5‐triaza‐7‐phosphaadamantane) or in situ generated N‐heterocyclic carbenes. The resulting diamagnetic, square planar NiII complexes were characterized by spectroscopic methods and X‐ray diffraction.

Ru‐Catalyzed Sequential Dehydrogenative Friedlander Reaction/sp3 C–H Activation/Knovenagel Condensation in the Regioselective Synthesis of Chimanine B Analogues

Choline chloride (ChCl) based deep eutectic solvent (DES), facilitated the regioselective synthesis of (E)‐1‐(4‐phenyl‐2‐styrylquinolin‐3‐yl)ethan‐1‐one (4), and (E)‐3‐phenyl‐1‐(4‐phenyl‐2‐((E)‐styryl)quinolin‐3‐yl)prop‐2‐en‐1‐ones, (5) from the corresponding 2‐amino‐5‐chloro benzhydrol, (1) in one‐pot strategy. The 2‐methyl‐3‐acetylquinoline generated in situ from the 2‐amino‐5‐chloro benzhydrol, (1) and acetyl acetone, (2) via dehydrogenative Friedlander reaction in DES could enable subsequent regio‐selective C‐2 methyl group sp3 C–H activation and rapid alkenylation with alcohols, (3) to provide the desired (E)‐2‐styrylquinolin‐3‐yl)ethan‐1‐ones, 4 in short reaction time and high yields and purity. Likewise, through the simultaneous C‐2 and C‐3 sp3 C–H activation with aromatic alcohols, (3) the (E)‐2‐styrylquinolin‐3‐yl)prop‐2‐en‐1‐ones, (5) formation was carried out in DES in high yields and purity. The physicochemical properties viz., UV/Vis, and fluorescence studies of the synthesized compounds were investigated. The absorption and emission properties of these luminophores are attributable to the presence of auxochromes in the 6‐position of quinoline moiety, styryl‐functional group at the 2‐position, and the enone group at 3‐position.

Preparation of TiO<sub>2</sub> Thin Films by Sol-Gel Method and Analysis of its Transmittance Based on Computer Image Processing

TiO2 films were prepared by sol-gel method with butyl titanate, anhydrous ethanol, acetyl acetone and hydrochloric acid as raw materials, which were sintered at 380 °C and 530 °C respectively to obtain TiO2 films. XRD was used for analyzing the crystal structure of TiO2 film, and ImageJ software was used to detect the light transmittance of TiO2 film samples. The results show that the film sintered at 530 °C is brookite structure and the film sintered at 380 °C is anatase structure. The increase of sintering temperature is not conducive to the growth of TiO2 film grains. TiO2 films sintered at 380 °C have good light transmittance.

Determination of Pramipexole Dihydrochloride in Tablet Dosage Forms by Visible Spectrophotometric Method Using Acetyl Acetone-Formaldehyde Reagent

A simple and sensitive visible spectrophotometric method has been developed for the determination of pramipexole dihydrochloride (PPD). The method is based on the condensation of the drug with acetyl acetone and formaldehyde producing a yellow colored Hantzsch condensation product having maximum absorption at 455 nm. The method is optimized for pH, concentration of reagents (acetyl acetone and formaldehyde) required, temperature and heating time. Beer’s law was obeyed in the concentration range of 5–150 μg mL-1. Molar absorptivity, Sandell’s sensitivity, limit of detection and limit of quantification were calculated and were found to be 5.23 x 103 L mole-1 cm-1, 0.0849 μg cm-2, 0.449 μg mL-1, and 1.362 μg mL-1, respectively. The method was applied to different tablet dosage forms containing PPD. The results of the proposed method were compared with the reported UV spectrophotometric method. The new method was found to be simple, accurate (t-test), and reproducible (F-test).

A Comparative Investigation of the Role of the Anchoring Group on Perylene Monoimide Dyes in NiO-Based Dye-Sensitized Solar Cells.

The anchoring group of a sensitizer may strongly affect the overall properties and stability of the resulting dye-sensitized solar cells (DSSCs) and dye-sensitized photoelectrosynthetic solar cells (DSPECs). The properties of seven perylene monoimide (PMI) dyes have been comprehensively studied for their immobilization on nanocrystalline NiO film. The PMI dyes differ only by the nature of the anchoring group, which are: carboxylic acid (PMI-CO2 H), phosphonic acid (PMI-PO3 H2 ), acetyl acetone (PMI-acac), pyridine (PMI-Py), aniline (PMI-NH2 ), hydroxyquinoline (PMI-HQ), and dipicolinic acid (PMI-DPA). The dyes are investigated by cyclic voltammetry and spectroelectrochemistry and modeled by TD-DFT quantum chemical calculations. The mode of binding of these anchoring groups is investigated by infrared spectroscopy and the stability of the binding to NiO surface is studied by desorption experiments in acidic and basic media. The phosphonic acid group is found to offer the strongest binding to the NiO surface in terms of stability and dye loading. Finally, a photophysical study by ultrafast transient absorption spectroscopy shows that all dyes inject a hole in NiO with rate constants on a subpicosecond timescale and display similar charge recombination kinetics. The photovoltaic properties of the dyes show that PMI-HQ and PMI-acac give the highest photovoltaic performances, owing to a lower degree of aggregation on the surface.

Preparation and characterization of hydroxyl terminated liquid epoxidized natural rubber

Hydroxyl terminated liquid epoxidized natural rubber (HTLENR) was successfully synthesized via oxidative degradation of liquid epoxidized natural rubber (LENR) in the presence of cobalt (II) acetyl acetonate (CAA) as the oxidizing agent. The effect of reaction time on molecular weight, chemical structures and hydroxyl content of HTLENR were investigated. The weight average molecular weight (Mw) and polydispersity index (PDI) of the prepared HTLENR were determined using gel permeation chromatography (GPC). The result shows that as the reaction time increased, the Mw decreased indicating the occurrence of higher chain scission. It was found that the lowest Mw was achieved at 10 h reaction time where the Mw and Mn were 37,545 g/mol and 3,233 g/mol. The structural analysis and hydroxyl content of HTLENR on the other hand, were studied by using fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR). The presence of OH group was confirmed by FTIR analysis with the appearance of broad peak at 3,200 - 3,600 cm-1. Subsequently, NMR analysis also confirmed that the highest amount of hydroxyl content which is 7.56 % was achieved at the longest reaction time which is 10 h.

Impact of Acetyl Acetone on Zinc Uptake and Oxidative Stress in Cucumber (Cucumis sativus)

The purpose of this research is to determine the impacts of acetyl acetone on zinc uptake and oxidative stress in cucumber (Cucumis sativus) seedlings grown in hydroponic solutions. Thirty seedlings of cucumber were collected from Kura local government area Kano, Kano state. Concentrations of Zn2+ in the hydroponics were varied from 0.000 to 0.025 mol dm-3 and of acetyl acetone were also varied from 0.000 to 0.025 mol dm-3. The seedlings were replanted and kept at Department of Agriculture Kano University of Science and Technology, Wudil garden. The weight of plants increased significantly (p<0.05) with concentration of Zn2+ in the absence of acetyl acetone and highly insignificantly (p>0.05) with concentration of acetyl acetone in the absence of Zn2+. In the presence of acetyl acetone and Zn2+ plant weight decreased highly insignificant (p>0.05). Leaf fall was observed from plants in all hydroponic, the number of falling leaves was insignificant (p>0.05) with concentration of Zn2+ but it is insignificant (p>0.05) with concentration of acetyl acetone and highly insignificant in the presence of acetyl acetone and Zn2+ (p>0.05). The volume of the solution decreased highly significant (p<0.05) with concentration of Zn2+ and significant with concentration of acetyl acetone (p<0.05) the volume also increased insignificantly in the presence of acetyl acetone and Zn2+ (p>0.05). The pH values of treated hydroponics before replanting and after harvest were insignificant with increased in the concentration of Zn2+ (p>0.05). Both shoot and root zinc accumulated were insignificant at lower concentration of Zn2+ (p>0.05) and significant at higher concentration of Zn2+ (p<0.05). The zinc translocation factor decreased highly insignificantly (p>0.05) at lower concentration of Zn2+ and significant at higher concentration of Zn2+ (p>0.05) in treated plants compared to control. The chlorophyll, carotenoid and proline content varied in the presence and absence of acetyl acetone and or combination of the two, with (p<0.05) or (p>0.05).

One-pot synthesis of thiazolo[3,2-a]pyrimidine derivatives, their cytotoxic evaluation and molecular docking studies.

An economical, simple and efficient one-pot method has been developed for the synthesis of thiazolo[3,2-a]pyrimidine hydrobromide derivatives. 2,4-diaryl-6,7,8,9-tetrahydro-4H-benzo[4,5]thiazolo[3,2-a]pyrimidine hydrobromides were synthesized by the α-bromination of cyclohexanone with N-Bromosuccinamide (NBS) and followed by cyclization with 3,4-dihydropyrimidine-2(1H)-thiones, respectively, in the presence of p-toluenesulfonic acid (PTSA) in acetonitrile. However when cyclohexanone was replaced by acetyl acetone and alpha-tetralone gave the corresponding 1-(3-methyl-5,7-diaryl-5H-thiazolo[3,2-a]pyrimidin-2-yl)ethan-1-one hydrobromide and 9,11-diaryl-6,11-dihydro-5H-naphtho[1',2':4,5]thiazolo[3,2-a]pyrimidine hydrobromide derivatives, respectively. The significant features of this method are novel, simple, inexpensive experimental procedure, short reaction time, and good yield. The some of the synthesized compounds were evaluated for cytotoxic activity against human lung adenocarcinoma cell line (A549), human breast carcinoma cell line (MCF-7), human cervical cancer cell line (HeLa) and human neuronal carcinoma cell lines (SKNSH). Tested compounds 5(b-e) showed the excellent anticancer activity against various cell lines. Particularly compound 5c with IC50 value of 2.2±0.6μM against A549 and compound 5e with IC50 value of 5.6±0.4μM against HeLa showed best cytotoxic effects. Furthermore, Molecular docking study was performed for some of the synthesized compounds 5(b-e) against topoisomerase-II by using Auto dock method. Docking results of the compounds 5c, 5d, and 5e exhibited higher cytotoxic activity than the standard doxorubicin.

Direct Growth of Bismuth Vanadate Thin Film Arrays on FTO via Galvanic Deposition Mediated by BiOI Nanosheets for Fabrication of Photoelectrochemical Non-Enzymatic Dopamine Sensing Platform

Development of a photoelectrochemical (PEC) sensor utilizing the energy of photon for the detection of bioanalytes is a challenging task. We hereby propose the easiest development of PEC sensor based on bismuth vanadate (BiVO4) photoanode on fluorine doped tin dioxide (FTO) electrode for sensing of bioanalytes. The fabrication of BiVO4/FTO electrode was performed by an extremely simple and energy efficient method called galvanic deposition. This was achieved in a two-step process viz. development of bismuth oxyiodide (BiOI) on FTO-glass electrode by galvanic deposition (BiOI/FTO) followed by moderate temperature annealing of BiOI/FTO in presence of Vanadyl (IV) acetyl acetonate to form the final electrode. The BiOI/FTO and BiVO4/FTO were thoroughly characterized by physicochemical and electrochemical means. The resultant structure revealed formation of a monoclinic scheelite BiVO4 (ms-BiVO4) structure which has the highest photocatalytic response compared to the other phases of BiVO4. One of the photoelectrochemical applications of ms-BiVO4 in the detection of bioanalyte was performed through the sensing of dopamine (DA). The BiVO4/FTO electrode exhibited high sensitivity (0.257 nA μM−1 cm−2), good linear range of concentration (102–106 μM) and a low limit of detection (0.154 μM) as a sensor for DA. The BiVO4/FTO electrode showed high reproducibility (RSD <4% under optimal condition), good stability, and high resistance against the polydopamine (PDA) fouling. The electrode was successfully demonstrated to perform the detection of DA including in real serum samples.

Morphological study of TiO₂ thin films doped with cobalt by Metal Organic Chemical Vapor Deposition

In this work, we present the synthesis of thin films of TiO2 doped with cobalt using the MOCVD technique, allowing the growth of coatings with controlled morphology and a faster deposit speed, as compared to other techniques. In addition, the synthesis parameters necessary for the reproducibility of the films were obtained. Anatase thin films doped with cobalt were prepared by the Metal Organic Chemical Vapor Deposition technique working in pulsed injection mode using a mixture of titanium (IV) isopropoxide and acetyl acetonate of cobalt at different concentrations as the precursor. The films were deposited on silicon (1 0 0) substrates at temperature of 650 °C. The crystalline structure of the deposited films was characterized by X-ray diffraction (XRD) and Raman spectroscopy. The characteristic XRD peaks and vibrational modes of TiO2 corresponding to the anatase phase were observed in all cases, without any secondary or mixed phase. On the other hand, the scanning electron microscopy (SEM) observations show that the film surfaces are formed by a higher number of porous, which are characteristic of the anatase films and the corresponding Energy Dispersion Spectroscopy (EDS) shows the elemental composition.

Reduction of chromate with UV/diacetyl for the final effluent to be below the discharge limit

Reduction of Cr(VI) to Cr(III) is helpful to lower the toxicity risk and also necessary for the removal of chromium from waste streams through alkaline precipitation. We compared the reduction of Cr(VI) in six UV systems with oxalic acid (OA), ethylenediaminetetraacetic acid (EDTA), salicylic acid (SA), hydroquinone (HQ), acetylacetone (AA) and diacetyl (BD) as chelating or non-chelating photo-activators. Overall, HQ, AA and BD were much more efficient than the carboxylic acids for the photo-reduction of Cr(VI). By introduction of UV to HQ system, the pseudo-first-order rate constant of Cr(VI) reduction at pH 5.1 was increased about 50 times. However, due to the formation of colloidal polymers, the UV/HQ treated solutions were dark in color and had a high turbidity (82 NTU). The effects of AA and BD on the photoreduction of Cr(VI) were similar. The UV/BD treated solution was colorless and clear with a turbidity lower than 1 NTU and a residual Cr less than 0.1 mg/L. The results demonstrate that UV/BD is a promising approach for the treatment of Cr(VI)-laden wastewater. The findings here also suggest that utilization of diketones in redox conversion of contaminants is a topic deserving further research.

Synthesis of Pyrano[2,3‐d]pyrimidine‐2,4‐diones and Pyridino[2,3‐d]pyrimidine‐2,4,6,8‐tetraones: Evaluation Antitumor Activity

AbstractA series of some novel pyrano[2,3‐d]pyrimidine 4–10 with 75–95% yields and pyridino[2,3‐d]pyrimidine derivatives 11–16 with 75–92% yields is reported. The building structures have been achieved by reaction of 5‐arylidene barbituric acid 2 and active nucleophile carbon or nitrogen as examples barbituric acid and acetyl acetone or refluxing of bispyrimidine‐2,4,6‐trione derivative 3 with cyclizing reagents such as phosphorous pentoxide, hydrazine hydrate and aminothiazole. The newly synthesized structures have been elucidated on the basis of their spectral analysis. Some selected members were screened for antitumor activity. Among the screened compounds 9, 16, 7, 10 and 8 exhibited high antitumor activity.

Synthesis of TiB₂ Powders with Hexagonal Morphology by Sol-Gel Method.

TiB₂ powders were successfully synthesized by carbothermal reduction of Ti-C-O-B precursor in argon at 1450 °C for 2 h. And the Ti-C-O-B precursor was formed by sol-gel method using titanium butyrate (Ti(OC₄H9)₄), fructose (C6H12O6), boric acid (H₃BO₃), and acetyl acetone (acac). Furthermore, thermogravimetric analysis-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), Raman, scanning electron microscope (SEM) and energy dispersive spectrum (EDS) were employed to analyze and characterize the precursor and TiB₂ powders. Here, acac as stabilizer was studied using FITR when it reacted with Ti(OC₄H9)₄ and the stable six-member ring was formed in order to prevent the nucleophilic attack of water, which reduced the hydrolysis rate of Ti(OC₄H9)₄. Besides, the composition of TiB₂ phase was tested by the Raman spectra, and the results showed that the peaks at 263 cm-1, 410 cm-1, and 598 cm-1 were ascribed to the characteristic peaks of TiB₂. Finally, the photomicrograph revealed TiB₂ powders with a hexagonal morphology and the average grain size of TiB₂ particles was ca. 1 um. The EDS indicated that the particles contain elements of Ti and B according to dot and line scan.