Adibah Izzati Daud

Synthesis and characterization of N-(4- Aminophenylethynylbenzonitrile)-N -(1-naphthoyl)thiourea as single molecular chemosensor for carbon monoxide sensing

This contribution reports on the design, preparation, and characterization of a novel acetylide-thiourea presenting N-(4-Aminophenylethynylbenzonitrile)-N′-(1-naphthoyl)thiourea (AETU) obtained from continuous reaction of intermediate compound 4[(4aminophenyl)ethynyl benzonitrile] (AMEB) with 1-naphthoyl chloride prior to form an active substrate for the detection of carbon monoxide (CO). These compounds were then characterized via several spectroscopic and analytical methods, namely Fourier transform infrared spectroscopy, UV–visible spectroscopy, nuclear magnetic resonance (1H and 13C NMR), carbon, hydrogen, nitrogen, and sulfur elemental analysis, and Thermogravimetric analysis. The performance of sensor response toward CO was measured using difference response in spectral features of UV–VIS spectrophotometry in thin-film studies with and without the presence of CO. The findings revealed that AETU possibly has an interaction with CO of concentrations 10, 20 and 30 ppm. In addition, quantum chemical calculations also proved that AETU exhibits potential sense interaction toward CO with stabilization energy−6.30 kJ/mol and interaction distance is about 3.14 Ǻ. This proposed material sensor gives an ideal indication for application in the aspect of direct detection of CO in real sample and for development of single molecule gas sensor devices. GRAPHICAL ABSTRACT

Synthesis and Characterization of Nitrobenzoylthiourea Derivatives as Potential Conductive Biodegradable Thin Films

Abstract The application of thiourea derivatives as conjugated molecular wire candidates in the field of material sciences has attracted great attention recently. To date, conjugated thiourea systems as molecular wires are surprisingly unexplored although the well-known rigid π-systems promise a wide range of electronic properties. Due to this matter, five novel thiourea derivatives A-ArC(O)NHC(S)NHAr-D with polar head and tail groups, namely NO2 (acceptor A) and alkoxy with varying chain lengths (donor D = OCnH2n+1, n = 6, 7, 8, 9, 10), were successfully synthesized and characterized. All compounds were characterized by IR, UV-vis, 1H and 13C NMR spectroscopy, and CHNS elemental microanalysis. The investigation of their potential as dopant systems in polymer conducting films has been accomplished by incorporating of chitosan via the solution casting technique. The conductivity values were obtained using impedance spectroscopy. They show that the ionic conductivities of the N-(4-alkoxyphenyl)-N’-(4-nitrobenzoyl)thioureas increase with increasing chain length of the alkoxy chain. The compounds exhibit great potential for the exploration of future applications as doping systems in conductive materials. GRAPHICAL ABSTRACT

Theoretical and Spectroscopic Studies of N-([4-aminophenyl]ethynyltoluene)-N’-(1-naphthanoyl thiourea (ATT) as Carbon Monoxide Gas Chemosensor

Acetylide and thiourea moieties individually provides a wide range of electronic properties as they possess electronic delocalization in extended rigid π orbital system in their designated structures. In this work, a new derivative of N-([4–aminophenyl] ethynyltoluene)-N’-(1-naphthanoyl) thiourea (ATT) was successfully synthesized and spectroscopically characterized by using FT-IR, NMR, and UV-Vis analysis. In turn, the development of new sensing material thin-film based on ATT has been accomplished by incorporating with polyvinyl chloride (PVC) via dip-coating technique. The difference in absorption behavior using UV-visible spectroscopic analysis was employed to determine the sensitivity of thin-film towards carbon monoxide (CO) gas of 10, 20, and 30 ppm. ATT exhibits high sensitivity towards 30 ppm CO gas with 55% sensitivity. Quantum mechanical calculation via Gaussian 09 shows that ATT has potential van der Waals interaction towards CO with stabilization energy-6.54 kJ/mol and 3.14Ǻ of interaction distance between substrate and analyte. It is proven that ATT as single molecule gives great potential to be explored and used as sensing material application particularly in CO detection.

Understanding the properties of chitosan aryl substituted thioureas in their role and potential as antibacterial agents

In this study, the effort was to design and synthesize a series of thiourea-chitosan derivatives featuring five aryl substituted members namely N-chitosan-N’-(4-nitrobenzoyl) thiourea (1), N-chitosan-N’-(4-chlorobenzoyl) thiourea (2), N-chitosan-N’-(4-methylbenzoyl) thiourea (3), N-chitosan-N’-(2-iodobenzoyl) thiourea (4), and N-chitosan-N’-(2-methylbenzoyl) thiourea (5) via SN2 reaction pathway having different donating and withdrawing groups. Their molecular structures were then characterised by FT-IR, UV-Vis, and thermogravimetric analysis (TGA). The antimicrobial activities of these derivatives against four species bacteria Bacillus cereus, Staphylococcus aureus, Salmonella typhi, and Escherichia coli of both Gram-positive and Gram-negative type bacteria at minimum concentration 6mg/ml were carried out to investigate their potential as antibacterial agents. Compound 1 exhibited specific activity as it can only inhibit Gram-positive bacteria while other compounds 2-5 showed broad range spectrum activit...

Bringing forward the new generation of alkoxy-thiourea as potential treatment for Acanthamoeba keratitis

Alkoxy substituted thiourea derivatives with general formula of A-ArC(O)NHC(S)NHAr-D which A represents the methoxy group and D denotes –OCnH2n+1 have been successfully synthesised and characterized. In turn, all the synthesised molecules were assayed for anti-amoebic activities towards Acanthamoeba sp to examine the cytotoxicity effect at their IC50 and membrane permeability. As predicted, the findings showed that the synthesised molecules owing promising anti-amoebic activity towards Acanthamoeba sp. To support, the Acridine-orange/Propidium iodide (AOPI) staining result under fluorescence microscopy revealed the treated amoeba cells by these alkoxy thiourea derivatives exhibited loss in their membrane permeability.

The Effects of Calcination Temperatures in the Synthesis of Nanocrystalline Magnesium Oxide via Sol-Gel Technique

This study highlights on a convenient and optimised method for the preparation of nanocrystalline magnesium oxide (MgO) catalyst via sol-gel combustion method. Nanocrystalline MgO was prepared by using polyvinyl alcohol (PVA) as a complexing agent and metal nitrate (Mg (NO 3 )2.6H2O) as a precursor. The obtained MgO powder was calcined at 200 °C, 400 °C, 600 °C and 800 °C. All the MgO calcined samples including commercial MgO were characterised using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-Ray diffraction (XRD) and N2 adsorption-desorption Brunauer–Emmett–Teller (BET). From FTIR analysis, the appearance of a peak at 3700 cm-1 represent the O-H stretching bonded with Mg and the broad absorption peak at 3421 cm-1 indicates O-H stretching band which is due to the absorption of moisture from the surrounding. (BET) results indicate the MgO sample that has been calcined at 400 °C shows the largest surface area. SEM images show there is porosity in all MgO powder. While XRD patterns revealed that higher temperature of calcination gives higher crystallinity of the MgO samples.