Sains Malaysiana 37(2): 201-203(2008)
Synthesis and Characterisation of Tris(1-carboxyl-2-phenyl-1,2-ethyleno dithiolenic-S,S’) Tungsten Complex as Photocatalyst for Photolysis
of H2O Molecules
(Sintesis dan Pencirian Kompleks Tris[1-karboksil-2-fenil-1,2-etilenoditiolenik-S,S’]
Tungsten sebagai Fotomangkin untuk Fotolisis Molekul H2O)
Fadhli Hadana Rahman, Rusli Daik & Mohammad Kassim
School of Chemical Sciences and Food Technology
Faculty of Science and Technology, Universiti Kebangsaan Malaysia
43600 UKM Bangi, Selangor, Malaysia
Khuzaimah & Wan Ramli Wan Daud
Department of Chemical and Process Engineering
Faculty of Engineering, Universiti Kebangsaan Malaysia
43600 UKM Bangi, Selangor, Malaysia
Received: 4 April 2007 / Accepted: 13 July 2007
ABSTRACT
Tris(1-carboxyl-2-phenyl-1,2-ethylenodithiolenic-S,S’) tungsten complex is one of the most promising photocatalyst to be used in photolysis of water to produce hydrogen. The first step of the synthesis involves a metathesis reaction of tetrapropylammonium bromide [{(C3H7)4N}Br] and ammonium tetrathiotungstate [(NH4)2WS4] to form a tetrapropylammonium tetrathiotungstate [{(C3H7)4N}2WS4] (precursor). Then, the precursor was reacted with phenylacetylenecarboxylic acid (C9H6O2) to form tris(1-carboxyl-2-phenyl-1,2-ethylenodithiolenic-S,S’) tungsten complex (C27H18O2S6W). The infra-red, ultra violet/visible (UV/Vis) spectrum, nuclear magnetic resonance (NMR) and elemental micro-analysis of C, H, N and S agreed with the characteristic of the tris(1-carboxyl-2-phenyl-1,2-ethylenodithiolenic-S,S’) tungsten complex. The (W-S), (C-S) and (C=O) stretching frequencies were detected at 511, (1470 and 1035) and 1655 cm-1, respectively. The 1H NMR spectrum showed six protons in the complex. The 13C NMR showed only 7 signals for carbon atom in the benzene ring, ethylene groups and carboxylic acid pendant group due to the symmetry of the molecules. The reaction yield was about 50 percent. Photolysis of acetone spiked H2O showed that the catalyst was able to produced 1.8µmol/h hydrogen.
Keywords: dye-sensitised solar cell; hydrogen; photolysis; sunlight; tungsten
ABSTRAK
Kompleks tris(1-karboksil-2-fenil-1,2-etilenoditiolenik-S,S’) tungsten merupakan salah satu daripada kompleks yang berpotensi tinggi untuk digunakan bagi proses fotolisis air untuk menghasilkan gas hidrogen. Langkah pertama sintesis melibatkan tindak balas metatesis di antara tetrapropilammonium bromida [{(C3H7)4N}Br] dan ammonium tetratiotungstat [(NH4)2WS4] untuk menghasilkan tetrapropilammonium tetratiotungstat [{(C3H7)4N}2WS4] (prekursor). Seterusnya prekusor bertindak balas dengan asid fenilasetilenakarboksilik (C9H6O2) dan membentuk kompleks tris(1-karboksil-2-fenil-1,2-etilenoditiolenik-S,S’) tungsten (C27H18O2S6W). Molekul telah diciri dengan kaedah spketroskopi inframerah (IR), ultraviolet/boleh nampak (UV/Vis), resonans magnet nuklear (NMR) dan analisis-mikro unsur C, H, N dan S. Spektrum IR menunujukkan kehadiran frekuensi regangan (W-S), (C-S) dan (C=O) masing-masing pada 511, (1470 dan 1035) dan 1655 cm-1. Spektrum NMR 1H menunjukkan kehadiran 6 proton kumpulan propil dan spektrum NMR 13C hanya menunujukkan 7 atom C bagi gelang benzena, etilena dan asid karbosilik. Hanya bilangan setara isyarat resonans 1H dan 13C dikesan kerana struktur mempunyai satah simetri yang tinggi. Peratus hasil kompleks agak rendah (50%) disebabkan kesukaran untuk memisahkan isomer yang terbentuk. Ujian fotolisis air yang dicampur aseton memnunjukkan kemampuan fotomangkin untuk menghasilkan hidrogen pada kadar 1.8µmol/j.
Kata kunci: bahan pewarna-pemeka sel solar; hidrogen; fotolisis; sinaran matahari; tungsten
RUJUKAN/REFERENCES
Alonso, G., Berhault, G. & Chianelli, R. R. 2001. Synthesis and characterization of tetraalkylammonium thiomolybdates and thiotungstate in aqueous solution. Inorganica Chimica Acta. 316:105-109.
Bamwenda, G. R., Sayama, K. & Arakawa, H. 1999. The effect of selected reaction parameters on the photoproduction of oxygen and hydrogen from a WO3-Fe2+-Fe3+ aqueous suspension. Journal of Photochemistry and Photobiology A: Chemistry. 122: 175-183.
Fadhli Hadana Rahman, Mohammad Kassim, Rusli Daik & Wan Ramli Wan Daud. 2004. Dithiolene tungsten photocatalyst precursor for water electrolysis. Proceedings of National Chemical Engineering Seminar (Medan, Indonesia). pp: B-03-1 – B-03-5.
Fujishima, A. & Honda, K. 1972. Electrochemical photolysis of water at a semiconductor electrode. Nature. 238: 37-38.
Humphry-Baker, R., Mitsopoulou, C. A., Katakis, D. & Vrachnou, E. 1997. Photophysical study of the decomposition of water using visible light and tungsten tris(dithiolene) as photosensitizers-catalyst. Journal of Photochemistry and Photobiology 114: 137-144.
Samios, J., Katakis, D., Dellis, D., Lyris, E. & Mitsopoulou, C. A. 1998. Solvation and catalyst-substrate superstructure of a tungsten tris(dithiolene) complex dissolved in water-acetone. J. Chem. Soc. Faraday Trans 94: 3169-3175.
Serpone, N. 1997. Relative photonic efficiencies and quantum yields in heterogeneous photocatalysis. Journal of Photochemistry and Photobiology. 104: 1-12.
Umakoshi, K., Nishimoto, E., Sokolov, M., Kawano, H., Sasaki, Y. & Onishi, M. 2000. Synthesis, structure and properties of sulfide-bridge dinuclear tungsten(V) complex of dithiolene. Journal of Organometallic Chemistry 611: 370-375.
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