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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Development of Ultrafast Photochromic Organometallics and Photoinduced LinkageIsomerization of Arene Chromium Carbonyl Derivatives
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Development of Ultrafast Photochromic Organometallics and Photoinduced LinkageIsomerization of Arene Chromium Carbonyl Derivatives

机译：超快光致变色有机金属化合物的开发和芳烃羰基羰基衍生物的光致键合异构化

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摘要

We review recent studies of processes relevant to photoinduced linkage isomerization of organometallic systemswith the goal of preparing organometallics with an efficient and ultrafast photochromic response. Theorganometallic system thus corresponds to two linkage isomers with different electronic environments thatare responsible for different optical properties. Much of this work has focused on examining processes followingirradiation of cyclopentadienyl manganese tricarbonyl derivatives (compounds 3-21) including solventcoordination, thermal relaxation, solvent displacement by tethered functional groups (chelation), dissociationof tethered functional groups, and linkage isomerization. A new platform is investigated for obtaining aphotochromic response in new experiments with arene chromium dicarbonyl complexes. A photochromicresponse is observed for arene chromium dicarbonyl complexes with tethered pyridine and olefin functionalgroups based on light-driven linkage isomerization on the nanosecond time scale. Irradiation at 532 nm of 23([Cr{|?~6-C_6H_5CH(2-Py-_|êN)CH_2CH=2}(CO)_2])(Py=pyridine) results in the isomerization to22Kr{?~C_6H_5CH(Py)CH_|?~2-CH=2}(CO)_2]), and 355 nm irradiation isomerizes22to23.The ultrafast linkageisomerization has been investigated at room temperature in n-heptane solution on the picosecond to microsecondtime scale with UV- or visible-pump and IR-probe transient absorption spectroscopy by comparing the dynamicswith model compounds containing only a tethered pyridine. Irradiation of 24 ([Cr{|?~6-C_6H_5(CH_2)_3(2-Py)}(CO)_3])and 25 ([Cr{|?~6-C_6H_5(CH_2)_2(2-Py)}(CO)_3]) at 289 nm induces CO loss to immediately yield a Cr—heptanesolvent coordinated intermediate of the unsaturated Cr fragment, which then converts to the |êN~1-pyridinechelate within 200 and 100 ns, respectively. Irradiation of 26 ([Cr{|?~6-C_6H_5CH_2(2-Py)} (CO)_3]) also inducesCO loss to immediately yield three species: the Cr—heptane solvent coordinated intermediate, a |êN~1-Py nitrogenchelate, and an agostic |?~2-chelate in which the pyridine is coordinated to metal center via a C-H agosticbond as opposed to the nitrogen lone pair. Both the transient Cr—heptane coordinated intermediate and theagostic pyridine chelate convert to the stable |êN~1-pyridine chelate within 50 ns. Similar reaction dynamicsand transient species are observed for the chelate 33 ([Cr{|?~6-C_6H_5CH_2(2-Py)-|êN}(CO)_2]) where a Cr—Pybond, not a Cr—CO bond, initially cleaves.
机译：我们审查与有机金属体系的光致键合异构化有关的过程的最新研究，目的是制备具有有效和超快光致变色反应的有机金属。因此，有机金属系统对应于具有不同电子环境的两个连锁异构体，其负责不同的光学性质。这项工作大部分集中在检查环戊二烯基锰三羰基衍生物（化合物3-21）的辐照后的过程，包括溶剂配位，热弛豫，溶剂被束缚的官能团取代（螯合），束缚的官能团解离和键合异构化。在新的实验中，研究了使用芳烃二羰基铬配合物获得光致变色响应的新平台。基于纳秒级的光驱动键异构化，观察到具有拴系的吡啶和烯烃官能团的芳烃二羰基铬的光致变色响应。在532 nm处照射23（[Cr {|？〜6-C_6H_5CH（2-Py-_ |êN）CH_2CH = 2}（CO）_2]）（Py =吡啶）异构化为22Kr {？〜C_6H_5CH（ Py）CH_ |？~~ 2-CH = 2}（CO）_2]），并在355 nm的辐射下异构化22至23。泵和红外探针瞬态吸收光谱法，通过与仅含有束缚吡啶的模型化合物进行动力学比较辐照24（[Cr {|？〜6-C_6H_5（CH_2）_3（2-Py）}（CO）_3]）和25（[Cr {|？〜6-C_6H_5（CH_2）_2（2-Py） }（CO）_3]）在289 nm处引起CO损失，立即产生不饱和Cr片段的Cr-庚烷溶剂配位中间体，然后分别在200 ns和100 ns内转化为|êN〜1-吡啶螯合物。辐照26（[Cr {|？〜6-C_6H_5CH_2（2-Py）}（CO）_3]）也引起CO损失，立即产生三种物质：Cr-庚烷溶剂配位中间体，|êN〜1-Py氮螯合物，和|β〜2螯合物，其中吡啶通过CH孤键与氮孤对相对于金属中心。瞬态Cr-庚烷配位中间体和水合吡啶螯合物在50 ns内均转变为稳定的|êN〜1-吡啶螯合物。对于螯合物33（[Cr {|？〜6-C_6H_5CH_2（2-Py）-|êN}（CO）_2]），观察到相似的反应动力学和瞬态物种，其中最初是Cr-Pybond而不是Cr-CO键分裂。

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