Khuzaimah Arifin

A DFT analyses for molecular structure, electronic state and spectroscopic property of a dithiolene tungsten carbonyl complex.

Bis(dithiolene) tungsten carbonyl complex, W(S2C2Ph2)2(CO)2 was successfully synthesized and the structure, frontier molecular orbital and optical properties of the complex were investigated theoretically using density functional theory calculations. The investigation started with a molecular structure construction, followed by an optimization of the structural geometry using generalized-gradient approximation (GGA) in a double numeric plus polarization (DNP) basis set at three different functional calculation approaches. Vibrational frequency analysis was used to confirm the optimized geometry of two possible conformations of [W(S2C2Ph2)2(CO)2], which showed distorted octahedral geometry. Electronic structure and optical characterization were done on the ground states. Metal to ligand and ligand to metal charge transfer were dominant in this system.

Temperature Effects on Stainless Steel 316L Corrosion in the Environment of Sulphuric Acid (H2SO4)

In its application, metal is always in contact with its environment whether air, vapor, water, and other chemicals. During contact, chemical interactions emerge between metals and their respective environments such that the metal surface corrodes. This study aims to determine the corrosion rate of 316L stainless steel sulphuric acid environment (H2SO4) with weight loss and electrochemical methods. The corrosion rate (CR) is value of 316L stainless steel by weight loss method with sulfuric acid (H2SO4) with concentration of 0.5 M. The result obtained in conjunction with the increase of temperature the rate of erosion obtained appears to be larger, with a consecutive 3 hour the temperature of 50°C is 0.27 mg/cm2h, temperature 70°C 0.38 mg/cm2h, and temperature 90 °C 0.52 mg/cm2h. With the electrochemical method, the current value increases by using a C350 potentiostal tool. The higher the current, the longer the time the corrosion rate increases, where the current is at 90 °C with a 10-minute treatment time of 0.0014736 A. The 316L stainless steel in surface metal morphology is shown by using a Scanning Electron Microscope (SEM).

Photocatalytic degradation of bromothymol blue with Ruthenium(II) bipyridyl complex in aqueous basic solution

Ru(II) bipyridyl photocatalyst with the formula, [Ru(bpy)2(o-CH3-bzpypz)](PF6)2] (Ru01) and [Ru(bpy)2(o-Cl-bzpypz)](PF6)2] (Ru02), where bpy = 2,2’-bipyridyl, o-CH3-bzpypz = (3-(pyridin-2-yl)-1H-pyrazol-1-yl)(o-tolyl)methanone and o-Cl-bzpypz = (2-chlorophenyl)(3-(pyridin-2-yl)-1H-pyrazol-1-yl)methanone, has been successfully synthesized and characterized on the basis of C, H, N elemental analysis, IR, UV-Vis and NMR spectroscopy. Both Ru(II) complexes showed Infrared stretching frequencies at 1742-1736 cm−1 v(C=O), 1605 cm−1 v(C=N) and 842-837 cm−1 v(PF). Full geometry optimization of the complex structures were carried out using DFT method with B3LYP exchange-correlation functional and 6-31G (d,p) basis-set for H, C, N, O and Cl; and LAN2LDZ basis set as effective core potential for the ruthenium centre. The highest-occupied molecular orbital (HOMO) energy levels of Ru01 and Ru02 are −5.63 and −5.55 eV, respectively. The photocatalytic properties of the Ru(II) complexes were evaluated by studying the de...

MOLECULAR AND ELECTRONIC STRUCTURES OF A NEW RUTHENIUM-TUNGSTEN BIMETALLIC COMPLEX USING DENSITY FUNCTIONAL THEORY CALCULATIONS

A potential dye sensitizer material for solar cell composed of a ruthenium-(4, 4’dimethyl-2, 2′-bipyridine)-isothiocyanatotungsten-[bis-(phenyl-1, 2-ethilenodithiolenic)] bimetallic complex structure was successfully developed using Density Functional Theory (DFT) calculations. The optimal structure was realized by calculations using the generalized gradient approximation (GGA) framework in a double numeric plus polarization (DNP) basis set using the following three functional methods: Becke-Pardew (BP), Becke-Lee-Yang-Parr (BLYP) and Perdew-Burke-Ernzerhof (PBE). The PBE calculation gave a structure with bond lengths and angles that approximated the experimental data. The restricted-spin calculation of PBE found that BM has 339 molecular orbitals in which the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are located at orbital numbers 312 and 313, respectively. The HOMO was delocalized over the W(S2C2) ring, the ruthenium metal center and the thiocyanate bridging ligand. In contrast, the LUMO was found mainly at the bipyridyl ligand with a small contribution from the ruthenium metal center. Electron excitation from the HOMO  LUMO occurred at 2964 nm with an excitation energy of 0.42 eV, which is depicted by the charge transfer from one metal to another (intervalence charge transfer, IVCT) or as a manifestation of the NCS bridging ligand.