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Inorganic and Transition Metal Azides
석원경,Thomas M. Klapötke 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.4
Experimental and theoretical studies show that all covalent azides possess a nonlinear azide group. They also rationalize this remarkable structural feature. We have seen that the most important non-covalent contributions in the covalently bound azides system (X-N1-N2-N3) are the π-delocalization over the entire molecule and a strong negative hyperconjugation which donates electron density from the filled σ (X-N1) orbital into the unfilled, antibonding π*(N2-N3) orbital. For transition metal azide complexes, a bent configuration and a small difference between the N-N bond lengths, generally the longer one being adjacent to the transition metal, were observed.
Computational Study on Spirocyclic Compounds as Energetic Materials (I)
석원경 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.4
The molecular structures of 2,6-diaza-1,3,5,7-tetraoxaspiro[3,3]heptane (1) and its dinitro derivative, 2,6- dinitro-2,6-diaza-1,3,5,7-tetraoxaspiro[3,3]heptane (2), were fully optimized without symmetry constraints at HF/6-31G* level of theory. A bisected conformation with respect to the ring is preferred with a C2 symmetric structure. The density of each molecule in the crystalline state was estimated to 1.12 and 2.36 g/cm3 using PM3/ VSTO-3G calculations from the molecular volume. The heat of formation was calculated for two compounds at the CBS-4M level of theory. The detonation parameters were computed using the EXPLO5 software: D = 6282 m/s, PC-J = 127 kbar for compound 1, D = 7871 m/s, PC-J = 307 kbar for compound 2, and D = 6975 m/s, PC-J = 170 kbar for 60% compound 2 with 40% TNT. Specific impulse of compound 1 in aluminized formulation when used as monopropellants was very similar to that of the conventional ammonium perchlorate in the same formulation of aluminum.
석원경,A. K. Gupta,Seung-Jae Roh,Wonjoo Lee,한성환 대한화학회 2007 Bulletin of the Korean Chemical Society Vol.28 No.8
To develop photo-sensitizers for dye-sensitized solar cells (DSCs) used in harvesting sunlight and transferring solar energy into electricity, we synthesize novel Ru(II) polypyridyl dyes and describe their characterization. We also investigate the photo-electrochemical properties of DSCs using these sensitizers. New dyes contain chromophore unit of dafo (4,5-diazafluoren-9-one) or phen-dione (1,10-phenanthroline-5,6-dione) instead of the nonchromophoric donor unit of thiocyanato ligand in cis-[RuII(dcbpy)2(NCS)2] (dcbpy = 4,4'-dicarboxy-2,2'-bipyridine) coded as N3 dye. For example, the photovoltaic data of DSCs using [RuII(dcbpy)2(dafo)](CN)2 as a sensitizer show 6.85 mA/cm2, 0.70 V, 0.58 and 2.82% in short-circuit current (Jsc), open-circuit voltage (Voc), fill factor (FF) and power conversion efficiency (Eff), which can be compared with those of 7.90 mA/cm2, 0.70 V, 0.53 and 3.03% for N3 dye. With the same chelating ligand directly bonded to the Ru metal in the complex, the CN ligand increases the Jsc value by double, compared to the SCN ligand. The extra binding ability in these new dyes makes them more resistant against ligand loss and photo-induced isomerization within octahedral geometry.
Strained-Ring Compounds Containing Nitro Groups as Potential Explosive Materials
석원경 대한화학회 2016 Bulletin of the Korean Chemical Society Vol.37 No.10
The molecular structures of spiro[2,2]pentane, bicyclo[1,1,1]pentane, and their nitro-substituted compounds were fully optimized without symmetry constraints at HF/6-31G* level of theory. A bisected conformation with respect to the ring in the spiro[2,2]pentane and its derivatives is preferred with a C2 symmetric structure. However highly strained bicyclo[1,1,1]pentane and its series of nitro-substituted compounds show close proximity of nonbonded bridge head carbons. In search for new explosive materials, energetic properties and density were investigated using semi-empirical PM3 calculations and the modified CBS-4M level of theory based on molecular geometries. The detonation parameters were also computed using the EXPLO5 software.