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Photocatalytic effects using a mixture of ruthenium tris-bipyridyl chloride and zinc phthalocyanine as photosensitizers

Photocatalytic effects using a mixture of ruthenium tris-bipyridyl chloride and zinc phthalocyanine as photosensitizers
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대학원 화학과
Photocatalytic effectsruthenium zinc phthalocyaninephotosensitizers
이화여자대학교 대학원
The mixture of Zinc phthalocyanine(ZnPc) and Ruthenium tris-bipyridyl complex (Ru(bpy)_(3)^(2+)) in Dimethylformamide(DMF)-water(9:1 by vol.) was irradiated with visible light. The decrease of the absorption peak of the Q band of ZnPc in the mixture was twice that observed in the only ZnPc. This was due to the additional photoreduction of ZnPc by Ru(bpy)_(3)^(2+) which absorbed shorter wavelength light. In the presence of Triehanolamine(TEOA). the decrease of the Q band was smaller than that observed in the abscence of TEOA. This was due to back electron transfer reaction between ZnPc and TEOA. The two photosensitizers(ZnPc. Ru(bpy)_(3)^(2+)) and their mixture with methyl viologen(MV^(2+), 5.2×10^(-4)M) as an acceptor, TEOA(l.2×10^(-3)M) as an elctron donnor in DMF-water (9:l by vol. ) were irradiated with visible light. The absorption spectrume of MV^(+). with characteristics bands at 395nm and 605nm appeared and were developed with time. When the sample solution was exposed to air in the dark, MV^(+) disappeared, while it continuously accumulated with irradiation unde er air. The efficiency of photoreduction of MV^(2+) by ZnPc was increased on addition of Ru(bpy)_(3)^(2+) complex. This was due to Ru(bpy)_(3)^(2+) as antenna set like photosynthesis in plants. But When the concentration of Ru(bpy)_(3)^(2+) in the mixture was increased, the efficiency of antenna set of Ru(bpy)_(3)^(2+) was decreased.;Zinc phthalocyanine(ZnPc)과 Ruthenium tris-bipyridyl complex(Ru(bpy)^(2+)_(3))의 1:1 혼합물을 포함하는 dimethylformamide(DMF)-water(9:1,by vol.)용액을 광조사하였다. ZnPc의 Q band의 흡광도 감소 속도는 ZnPc만 존재할 때 보다 ZnPc/Ru(bpy)^(2+)_(3) 혼합물인 경우가 약 2배 정도 컸다. 이는 Ru(bpy)^(2+)_(3)가 단 파장의 에너지를 흡수하여 ZnPc을 광환원 시키기 때문이다. ZnPc/Ru(bpy)^(2+)_(3) 1:1 혼합물에 Triethanolarmine(TEOA)이 존재하면 광환원된 ZnPc와 TEOA^(+) 사이에 back electron transefer reaction이 일어나 TEOA가 존재하지 않을 때 보다 Q band의 흡광도 감소 속도는 더 작아졌다. 세가지 경우의 광감제 즉 ZnPc. Ru(bpy)^(2+)_(3), ZnPc/Ru(bpy)^(2+)_(3) 와 methly viologen(MV^(2+), 5.2×10^(-4)M), 그리고 TEOA(1.2×10^(-3)M)을 포함한 DMF-water (9:1 by vol.) 용역을 가시광선 영역(λ>350nm)의 빛으로 조사하였다. 395nm과 605nm에서의 흡광도가 점차 증가 하였는데, 이는 MV^(+)의 특징 peak로, MV^(2+)가 광환원되어 MV^(+)이 생성되기때문이다. 광조사함에 따라 MV^(+)는 생성 축적되어 최대 파장에서의 흡광도가 증가하였다. ZnPc, Ru(bpy)^(2+)_(3) 각 각을 광감제로 사용한 경우 보다 ZnPc/Ru(bpy)^(2+)_(3) 혼합물을 광감제로 사용한 경우 MV^(2+)의 광환원 속도가 증가되었다. 이는 Ru(bpy)^(2+)_(3)가 단 파장의 빛을 흡수하여 ZnPc를 ZnPc^(-)로 광환원 시켜, ZnPc만 있을때 보다 MV^(2+)을 광환원 시킬 수 있는 ZnPc^(-)가 많아지기 때문이다. 즉 Ru(bpy)^(2+)_(3)가 식물 광합성 system에서의 chlorophyll과 같이 antenna pigment 역활을 한다고 보여진다. ZnPc/Ru(bpy)^(2+)_(3) 1:1 혼합물에서 Ru(bpy)^(2+)_(3)의 농도를 증가 시켰더니, Ru(bpy)^(2+)_(3)의 antenna 효과가 감소하였다.
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