The rotational motion of tolanes along their acetylene axis is not fully understood. What happens to the optical and electronic properties if the tolane backbone is forced into a twisted conformation? Several tethers were investigated to obtain tolanophanes, fixing the torsion angle of the two phenyl rings. X-ray crystal structures revealed tether-specific torsion angles in the solid state. The absorption, emission, and excitation spectra were recorded. Twisted tethered tolane conformers showed blue-shifted absorption; emission spectra were all torsionally independent and identical. The tethered tolanes were embedded in a rigid matrix by freezing to 77 K; well-resolved emission spectra were recorded for planar tolanes, but for twisted systems unexpectedly long-lived phosphorescence was observed. How is this triplet emission explained? Quantum chemical calculations (TDDFT/cam-B3LYP/6-31G*) of the unsubstituted tolane showed that intersystem crossing (ISC) is favored with large spin-orbit coupling, which occurs when the molecular orbitals are orthogonal to each other; this is the case at the crossing of S-1/T-7. Also, a small energy difference between singlet and triplet states is required; we found that ISC can favorably take place at four crossings: S-1/T-6, S-1/T-7, S-1/T-8,T-9, S-1/T-10.
Synthesis and Properties of Functional Twisted Tolanes
作者:Yury Kozhemyakin、Andreas Kretzschmar、Maximilian Krämer、Frank Rominger、Andreas Dreuw、Uwe H. F. Bunz
DOI:10.1002/chem.201701519
日期:2017.7.21
and optical properties of several novel fluorescent and/or phosphorescent bridged tolanes (tolanophanes) are reported and their optical and structural properties are investigated. Specifically, diiodinated and bisalkynylated tolanophanes were obtained, and characterized by spectroscopy and computational methods. They represent attractive buildingblocks for novel polymers and emissive solid‐state materials
Twisted Tethered Tolanes: Unanticipated Long-Lived Phosphorescence at 77 K
作者:Sebastian Menning、Maximilian Krämer、Benjamin A. Coombs、Frank Rominger、Andrew Beeby、Andreas Dreuw、Uwe H. F. Bunz
DOI:10.1021/ja400416r
日期:2013.2.13
tethered tolanes exist, and they all suffer from small twist angles (<35°). We report on tolanophanes containing a malonyl tether, where twist angles of almost 80° were reached. Long-lived phosphorescence (4 s at 77K) was recorded, and quantum-chemical calculations were performed to confirm the experimental results.
影响共轭体系内的通讯如二苯乙炔是分子电子学中的一个具有挑战性的课题。已知扭曲的 tolanes 的一些例子,其中通过空间阻碍在固态下实现了高扭曲。间隔系统的插入是定制旋转的另一种方式。仅存在少数此类系留托车道的示例,并且它们都具有小扭曲角 (<35°)。我们报告了含有丙二酰系链的 tolanophanes,其扭曲角达到了近 80°。记录了长寿命磷光(77 K 下 4 秒),并进行了量子化学计算以确认实验结果。
Bridged Tolanes: A Twisted Tale
作者:Sebastian Menning、Maximilian Krämer、Andrew Duckworth、Frank Rominger、Andrew Beeby、Andreas Dreuw、Uwe H. F. Bunz
DOI:10.1021/jo5010235
日期:2014.7.18
The rotational motion of tolanes along their acetylene axis is not fully understood. What happens to the optical and electronic properties if the tolane backbone is forced into a twisted conformation? Several tethers were investigated to obtain tolanophanes, fixing the torsion angle of the two phenyl rings. X-ray crystal structures revealed tether-specific torsion angles in the solid state. The absorption, emission, and excitation spectra were recorded. Twisted tethered tolane conformers showed blue-shifted absorption; emission spectra were all torsionally independent and identical. The tethered tolanes were embedded in a rigid matrix by freezing to 77 K; well-resolved emission spectra were recorded for planar tolanes, but for twisted systems unexpectedly long-lived phosphorescence was observed. How is this triplet emission explained? Quantum chemical calculations (TDDFT/cam-B3LYP/6-31G*) of the unsubstituted tolane showed that intersystem crossing (ISC) is favored with large spin-orbit coupling, which occurs when the molecular orbitals are orthogonal to each other; this is the case at the crossing of S-1/T-7. Also, a small energy difference between singlet and triplet states is required; we found that ISC can favorably take place at four crossings: S-1/T-6, S-1/T-7, S-1/T-8,T-9, S-1/T-10.