DYNAMICS OF THE TRIPLET-STATE AND THE REVERSE PROTON-TRANSFER OF 3-HYDROXYFLAVONE
DYNAMICS OF THE TRIPLET-STATE AND THE REVERSE PROTON-TRANSFER OF 3-HYDROXYFLAVONE
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DOI：
10.1021/j100353a029
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发表时间：
1989-08-10
影响因子：
--
通讯作者：
CHOU, PT
中科院分区：
文献类型：
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作者：
BREWER, WE;STUDER, SL;CHOU, PT
Ru（bpm）32+的单电子还原产生Ru（bpm）3+，其是比Ru（bpz）3+（Eox = 0.50 V）更强的还原剂（Eox = 0.73 V）。Ru-（bpm）3+的共轭酸[Ru 1 I（bpm）2（bpmH，）] 2+是比Ru（bpz）3+的相应形式（£ ox= 0.30 V; p £ a 7.1）更强的还原剂（£ ox = 0.50 V）和酸（p£ a 6.3）。因此，酸性和碱性形式的Ru（bpm）3+都还原MV 2+（分别为1.0 X 106和1.0 X 109 M-1 s-1）;只有碱性形式的Ru（bpz）3+能够进行该反应。在碱性溶液中，~* Ru（bpm）~（3+）被TEOA和EDTA猝灭生成Ru ~（-（bpm）~（3+））的效率至少与~* Ru（bpz）~（3+）的类似猝灭反应一样高;在MV ~（2+）存在下，MV ~（3+）的量子产率由一个简单的表达式给出：#（MV ~（3+））= 2 ijq 7 jce。不幸的是，Ru（bpm）32+和它的结合物的三个性质共同使它成为比Ru（bpz）32+更不理想的光敏剂：（1）显著更短的激发态寿命（~ 0.1 vs~ 1 μ s）;（2）较低的正激发态还原势（1.2 vs~ 1.6 V），导致Acq值较小，因此，对于可比的猝灭剂浓度，i; q值较小;（3）Ru（bpm）3+在水溶液中的两种酸碱形式对降解过程的不稳定性，使其不适合长期储存，而[Run（bpz）2（bpz*~）]+在碱性溶液中非常稳定。这项研究得到了美国能源部化学科学司基础能源科学办公室的部分支持，意大利的Consiglio Nazionale delle Ricerche（“Technologie e Metodologie Radiochimiche Avánzate”战略计划）的部分支持，以及意大利的Minisapella della Pubblica Istruzione（占40%）的部分支持。QGM和MZH之间的合作是美国-意大利合作研究计划的一部分。CFKR由NIH研究资源部生物医学研究技术计划（RR 00886）和德克萨斯大学奥斯汀分校联合支持。GN和MZH感谢Jennifer Meyer（NSF-REU参与者，1987年夏季）在初步寿命和猝灭测量中提供的帮助。
The one-electron reduction of Ru (bpm) 32+ generates Ru (bpm) 3+, which is a stronger reducing agent (£ ox= 0.73 V) than is Ru (bpz) 3+(£ ox= 0.50 V). The conjugateacid of Ru-(bpm) 3+,[Ru1I (bpm) 2 (bpmH,)] 2+, is a stronger reducing agent (£ ox= 0.50 V) and acid (p£ a 6.3) than is the corresponding form of Ru (bpz) 3+(£ ox= 0.30 V; p£ a 7.1). As a result, both the acidic and basic forms of Ru (bpm) 3+ reduce MV2+(1.0 X 106 and 1.0 X 109 M" 1 s" 1, respectively); only the basic formof Ru (bpz) 3+ is capable of that reaction. The efficiency of formationof Ru-(bpm) 3+() from the quenching of* Ru (bpm) 32+ by TEOA and EDTA in alkaline solution is at least as high as in the comparable quenching reactions of* Ru (bpz) 32+; in the presence of MV2+, the quantum yield ofMV,+ is given by a simple expression:#(MV,+)= 2 ijq7jce. Unfortunately, three properties of Ru (bpm) 32+ and its conjoiners conspire to make it a less desirable photosensitizer than Ru (bpz) 32+:(1) a significantly shorter excited-state lifetime (~ 0.1 vs~ 1 jus);(2) a less positive excited-state-reduction po-tential (1.2 vs~ 1.6 V), causing values of Acq, and hence i; q for comparable quencher concentrations, tobe smaller;(3) the instability of both acid-base forms of Ru (bpm) 3+ in aqueous solution toward degradative processes, making them unamenable to long-term storage, unlike [Run (bpz) 2 (bpz*~)]+, which is very stable in alkaline solution.Acknowledgment. This research was supported in part by the Office of Basic Energy Sciences, Division of Chemical Sciences, US Department of Energy, in part by Consiglio Nazionale delle Ricerche of Italy (Progetto Strategico “Tecnologie e Metodologie Radiochimiche Avánzate”), and in part by Ministero della Pubblica Istruzione of Italy (Quota 40%). The collaboration between QGM and MZH is part of the US-Italy Cooperative Research Program. CFKR is supported jointly by the Biomedical Research Technology Program of the Division of Research Re-sources of NIH (RR 00886) and by The Universityof Texas, Austin. GN and MZH acknowledge theassistance of Jennifer Meyer (NSF-REU participant, summer 1987) in the preliminary lifetime and quenching measurements.