Wan M. Khairul

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

Conductive biodegradable film of N-octyloxyphenyl-N′-(4-methylbenzoyl)thiourea

Thiourea derivatives are versatile family of ligands which provides wide range of electronic properties since they consist of rigid π-systems on their structures. In this work, a new type of thiourea compound with general formula Me-C6H4C(O)NHC(S)NHC6H4-OC8H17 of N′-(4-methylbenzoyl)thiourea (MBTU) was successfully synthesised and characterized by using NMR, FTIR and UV–vis analysis. The development of new conductive biodegradable film based on MBTU has been accomplished by incorporating chitosan to the polymer-dopant system via solution-cast technique. The impedance measurement technique was employed to determine conductivity of biodegradable film. It shows that, with the addition of MBTU, the increasing of conductivity is from 10−9 to 10−8 Scm−1. TNM results show that the conductivity of biodegradable film is governed by electronic conducting species. It is proven that MBTU compound exhibits promise and has great potential to be explored and used as doping system in conductive materials application in the future.

The Effect of Concentration of Lawsonia inermis as a Corrosion Inhibitor for Aluminum Alloy in Seawater

Lawsonia inermis also known as henna was studied as a corrosion inhibitor for aluminum alloy in seawater. The inhibitor has been characterized by optical study via Fourier transform infrared spectroscopy (FTIR). The FTIR proves the existence of hydroxyl and carbonyl functional groups in Lawsonia inermis. Aluminum alloy 5083 immersed in seawater in the absence and presence of Lawsonia inermis was tested using electrochemistry method, namely, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PP). EIS and PP measurements suggest that the addition of Lawsonia inermis has caused the adsorption of inhibitor on the aluminum surface. The adsorption behavior of the inhibitor follow Langmuir adsorption model where the value of free energy of adsorption, , is less than 40 kJ/mol indicates that it is a physical adsorption. Finally, it was inferred that Lawsonia inermis has a real potential to act as a corrosion inhibitor for aluminum alloy in seawater.

Bacteriostatic activities of N-substituted tris-thioureas bearing amino acid and aniline substituents

GRAPHICAL ABSTRACT ABSTRACT A series of tri-substituted thiourea derivatives were synthesized by the reaction of 1,3,5-triacetylbenzoyl isothiocyanate with aminoacids and aniline derivatives. All thiourea derivatives were characterized by FT-IR, 1H and 13C NMR spectroscopy. Antibacterial activities against wild-type Escherichia coli American Type Culture Collection 8739 were determined by use of the turbidimetric methodto evaluate the effect of varying amino groups on the synthesized thioureas. Tris-thiourea derivatives bearing ortho-chloroaryl substituents showed excellent antibacterial activity against E. coli with minimal inhibitory concentration (MIC) of 96 ppm. The optimum inhibition was dependent on the type of amines and the position of the halogen in aniline.

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.

Contribution of Methyl Substituent on the Conductivity Properties and Behaviour of CMC-Alkoxy Thiourea Polymer Electrolyte

An essentially linear conjugated thiourea system provides wide range of electronic properties as they consist of rigid π-systems on their structures. This study reported the synthetic, characterization and theoretical evaluation of molecular wire candidate bearing alkoxy thiourea derivative featuring methylbenzene head group. It was applied as dopant in Carboxymethyl-Cellulose (CMC) solution in order to form a conductive biodegradable thin film. According to the conductivity result, the developed system can be developed as electrical conductor as proven via both experimental and theoretical studies. Therefore, this type of A-ArC(O)NHC(S)NHAr-D molecular framework has opened wide possibilities to be applied in many micro-electronic application devices.

Star - shaped Thiourea Derivative as Single Molecule Conductive Thin Film

The electronic delocalization in extended π - orbital system of conjugated organic molecules br ings significant contribution and has lead for further investigation to exploit this system to be used as potential conductive thin film. In this work, a star - shaped thiourea, N 1 ,N 3 ,N 5 - tris(4 (nonyloxy)phenyl) - N ’ - (benzene - 1,3,5 tricarbonyl) thiourea ( STU ) based on Donor(D) - π - Acceptor(A) system was successfully synthesized from continuous reactions of intermediate compound 4 nonyloxy aniline hydrochloride with benzene - 1,3,5 - tricarboxylic acid chloride pri or to form active substrate in the form of film. These compounds were characterized via several spectroscopic and analytical methods namely IR, UV - Vis, CHNS elemental analysis,

1-(1,3-Benzothia­zol-2-yl)-3-(4-chloro­benzo­yl)thio­urea

The title compound, C15H10ClN3OS2, adopts a cis–trans configuration across the thiourea C—N bonds with respect to the positions of the benzothiazole and 4-chlorobenzoyl groups relative to thiono S atom. An intramolecular N—H⋯O hydrogen bond is present. In the crystal structure, molecules are linked by a weak intermolecular N—H⋯S hydrogen bond, forming centrosymmetric dimers.

Palladium(II) Picoline Thiourea Complex as Homogenous Catalyst in Heck Cross-Coupling Reaction in the Formation of C=C Bond

Palladium (II) complex containing picoline thiourea (Pd-PTu) was prepared by reacting bis (benzonitrile) palladium (II) chloride (Pd-PhCN) with N’-2-(5-picolyl)-N-4-bromobenzoylthiourea (PTu). All synthesized compounds have been characterized via several selected typical spectroscopic and analytical techniques namely elemental analysis, Infrared (IR) spectroscopy, Ultraviolet-visible (UV-Vis) spectroscopy, Nuclear Magnetic Resonance (1H and 13C NMR) and gas chromatography-flame ionization detector (GC-FID). For Pd-PTu, IR spectrum showed significant shift in the ν (C=N) on the pyridine ring and ν (C=S) stretching vibration at around 30cm-1 compared to the free ligand. The finding indicated that the expected coordination of ligand to the palladium metal centre took place via N and S atoms. The catalytic reaction was monitored using GC-FID with conversion of 83.81 %, proved that Pd-PTu can be used as an ideal homogenous catalyst in any Heck cross-coupling reactions in the near future.