Abstract
[G-2]-Br (5) and [G-2]-SCOCH3 (6) ([G-2]-X stands for second generation dendron with X at the focal point) can be synthesized from the monomer, 3,5-dihydroxybenzyl alcohol by ”convergent methodology”. Reaction of compound 5 and [K-18-crown-6-ether]2[Fe2S2(NO)4] (7) in a 2:1 molar ratio in THF can give the dinuclear {Fe(NO)2}9-{Fe(NO)2}9 dinitrosyl iron complex (DNIC) [Fe(SR)(NO)2]2 (R = [G-2]) (8). Reaction of compound 8 and dendron thiolate ([G-2]-S-) obtained from hydrolysis of compound 6 led to the production of mononuclear {Fe(NO)2}9 DNIC [Fe(SR)2(NO)2]- (R = [G-2]) (9). Both compound 8 and compound 9 were characterized by IR、UV-vis、1H NMR and MS. From the fluorescence emission spectra, compound 5 produces fluorescence emission around 318 nm upon compound 5 irradiated at 260 nm. In contrast to compound 5, the fluorescence of dendron ligand is quenched by the iron-sulfur [Fe2S2] core when compound 8 was irradiated in the same condition. Therefore, the light-harvesting property of the dendron ligand is confirmed. Compound 8 is stable in aerated solvent at 30 oC in the dark. However, compound 8 decomposes with increasing time upon compound 8 irradiated at 254 nm in the same condition. Upon the solution of compound 8 was treated with NO-trapping agent, 2-phenyl-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl (PTIO), EPR spectrum with five-line hyperfine coupling changes into the seven-line hyperfine signal of phenyltetramethylimidazoline-N-oxy (PTI, NO-trapped product) during the photolysis. The result demonstrated that photodecomposition of compound 8 produces free NO.