Lanthanide Photocatalysis

光催化 镧系元素 光化学 催化作用 反应性(心理学) 激进的 激发态 化学 组合化学 无机化学 有机化学 离子 医学 替代医学 病理 物理 核物理学
作者
Yusen Qiao,Eric J. Schelter
出处
期刊:Accounts of Chemical Research [American Chemical Society]
卷期号:51 (11): 2926-2936 被引量:201
标识
DOI:10.1021/acs.accounts.8b00336
摘要

The use of earth-abundant, cheap, potent, and readily available lanthanide photocatalysts provides an opportunity to complement or even replace rare and precious metal photosensitizers. Moreover, lanthanide photosensitizers have been demonstrated for the generation of a variety of reactive species, including aryl radicals, alkyl radicals, and others, by single-electron-transfer (SET) and hydrogen atom transfer (HAT) pathways under mild reaction conditions. Some lanthanide photocatalysts have unprecedented reducing power from their photoexcited states, achieving the activation of challenging organic substrates that have not otherwise been activated by reported organic or transition-metal photosensitizers. In this Account, we describe our recent advances in the rational design and strategic application of lanthanide photo(redox)catalysis. Our research goals include understanding the photophysics of lanthanide luminophores and incorporating them into new photocatalysis. Among the lanthanides, we have focused on cerium because of the doublet to doublet 4f → 5d excitation and emission, which affords good conservation of energy without losses through spin-state changes, as well as a large natural abundance of that element. We have performed structural, spectroscopic, computational, and reactivity studies to demonstrate that luminescent Ce(III) guanidinate-amide complexes can mediate photocatalytic C(sp3)-C(sp3) bond forming reactions. Taking advantage of the strong reducing power of the cerium excited states and the cerium-halogen bond forming enthalpies, we determined that the reactive, excited-state cerium metalloradical abstracts chloride anion from benzyl chloride to generate the benzyl radical. To control and predict the photocatalytic reactivities, we have also performed photophysical and photochemical studies on a series of mixed-ligand Ce(III) guanidinate-amide and guanidinate-aryloxide complexes to establish structure-property relationship for Ce(III) photocatalysts. We discovered that the emission color is directly related to ligand type and rigidity of the coordination sphere and that the photoluminescent quantum yield is correlated to variation in steric encumbrance around the cerium centers. The low excited-state reduction potentials ( E1/2* ≈ -2.1 to -2.9 V versus Cp2Fe0/+) and relatively fast quenching rates ( kq ≈ 107 M-1 s-1) toward aryl halides enabled the Ce(III) guanidinate-amide complexes to participate in photocatalytic C(sp2)-C(sp2) bond forming reactions through either inner-sphere or outer-sphere SET processes. We have also reported a simple, potent, and air-stable ultraviolet A photoreductant, the hexachlorocerate(III) anion ([CeIIICl6]3-). This complex is a potent photoreductant ( E1/2* ≈ -3.45 V versus Cp2Fe0/+) and exhibits a fast quenching kinetics ( kq ≈ 109-1010 M-1 s-1) toward organohalogens. The [CeIVCl6]2- redox partner can also act as a potent photo-oxidant though a (presumably) long-lived chloride-to-cerium(IV) charge transfer excited state (ε = ∼6000 M-1 cm-1), that was used to turnover photocatalytic dechlorination and Miyuara borylation reactions. With [CeIIICl6]3-, we achieved efficient photoinduced dehalogenation and borylation of unactivated aryl chlorides with broad substrate scope, through formally two-photon cycles where both Ce(III) and Ce(IV) act as photocatalysts. Lanthanide photoredox catalysis is now being applied in several contexts for reactions including photocatalytic dehydrogenation of amines, alkoxy-radical-mediated C-C bond cleavage and amination of alkanols, and C-H activation of alkanes. Overall, simple and potent lanthanide photocatalysis is expected to find practical applications in organic synthesis, pharmaceutical development, and small molecule activation.
最长约 10秒,即可获得该文献文件

科研通智能强力驱动
Strongly Powered by AbleSci AI
更新
PDF的下载单位、IP信息已删除 (2025-6-4)

科研通是完全免费的文献互助平台,具备全网最快的应助速度,最高的求助完成率。 对每一个文献求助,科研通都将尽心尽力,给求助人一个满意的交代。
实时播报
yellow完成签到 ,获得积分10
1秒前
虚幻元风完成签到 ,获得积分10
4秒前
xybjt完成签到 ,获得积分10
7秒前
巴达天使完成签到,获得积分10
13秒前
江三村完成签到 ,获得积分10
13秒前
量子星尘发布了新的文献求助10
31秒前
CyberHamster完成签到,获得积分10
41秒前
xiaohong完成签到,获得积分10
44秒前
朱比特完成签到,获得积分10
45秒前
46秒前
zmuzhang2019发布了新的文献求助10
52秒前
onestepcloser完成签到 ,获得积分0
52秒前
zoe完成签到 ,获得积分10
53秒前
发嗲的慕蕊完成签到 ,获得积分10
54秒前
Linson完成签到,获得积分10
55秒前
顾矜应助赵三岁采纳,获得10
1分钟前
yyy2025完成签到,获得积分10
1分钟前
木雨亦潇潇完成签到,获得积分10
1分钟前
香蕉觅云应助nine2652采纳,获得10
1分钟前
量子星尘发布了新的文献求助10
1分钟前
芳华如梦完成签到 ,获得积分10
1分钟前
1分钟前
1分钟前
1分钟前
土豆丝完成签到 ,获得积分10
1分钟前
琦琦完成签到,获得积分10
1分钟前
zzzz完成签到,获得积分20
1分钟前
GEZIKU完成签到 ,获得积分10
1分钟前
1分钟前
1分钟前
赵三岁发布了新的文献求助10
2分钟前
wwb完成签到,获得积分10
2分钟前
2分钟前
2分钟前
肯德基没有黄焖鸡完成签到 ,获得积分10
2分钟前
能干冰露完成签到,获得积分10
2分钟前
牛奶拌可乐完成签到 ,获得积分10
2分钟前
量子星尘发布了新的文献求助30
2分钟前
周小鱼完成签到 ,获得积分10
2分钟前
2分钟前
高分求助中
【提示信息,请勿应助】关于scihub 10000
Les Mantodea de Guyane: Insecta, Polyneoptera [The Mantids of French Guiana] 3000
徐淮辽南地区新元古代叠层石及生物地层 3000
The Mother of All Tableaux: Order, Equivalence, and Geometry in the Large-scale Structure of Optimality Theory 3000
Handbook of Industrial Diamonds.Vol2 1100
Global Eyelash Assessment scale (GEA) 1000
Picture Books with Same-sex Parented Families: Unintentional Censorship 550
热门求助领域 (近24小时)
化学 材料科学 医学 生物 工程类 有机化学 生物化学 物理 内科学 纳米技术 计算机科学 化学工程 复合材料 遗传学 基因 物理化学 催化作用 冶金 细胞生物学 免疫学
热门帖子
关注 科研通微信公众号,转发送积分 4038039
求助须知:如何正确求助?哪些是违规求助? 3575756
关于积分的说明 11373782
捐赠科研通 3305574
什么是DOI,文献DOI怎么找? 1819239
邀请新用户注册赠送积分活动 892655
科研通“疑难数据库(出版商)”最低求助积分说明 815022