Tetrathiafulvalene‐Fused Heterabuckybowl: Protonation‐Induced Electron Transfer and Self‐Sensitized Photooxidation

Abstract

The electron donor tetrathiafulvalene (D 1 )w as fused onto the electron-rich heterabuckybowl trichalcogenasumanene( D 2 )t hrougha ne lectron-deficient pyrazine unit (A) to give 1c, 1d, 2c,a nd 2d,f eaturing the D 1 -A-D 2 structure. Both D 1 and D 2 play ap ivotalr ole in intramolecular charge-transfer (ICT) transitions, consequently 1c, 2d, 2c, and 2d show ab road ICT band at 450-720 nm in steady state. They exhibit two charge-separated transient states, CS 1 and CS 2 ,t hat appear in sequence. CS 1 has as hort lifetime (542 fs), and the D 1 moiety on CS 1 is in the radical cation state with an absorption maximum (l max )a t8 89 nm. CS 1 then converts into CS 2 (l max ,1 105 nm) through an ICT betweenD 1 C + and D 2 ,a ffording D 1 (1Àd) C + and D 2 d C + .C ompounds 1c, 1d, 2c,a nd 2d show protonation-induced intramolecular electron transfer that leads to absorption at l = 700-1300 nm. Owing to the existence of an electron-rich C=Cb ond on the D 1 moiety and in situ generation of 1 O 2 by the pyrazine-fusedD 2 moiety,c ompounds 1c, 1d, 2c,a nd 2d display self-sensitized photooxidation in 50 s.[a] Dr.Scheme1.Synthesis of 1c, 1d, 2c,and 2d and relatedc ompounds:a)FeCl 3 , CH 2 Cl 2 /CH 3 NO 2 ,RT, 2h;b )1,2-diaminobenzene,A cOH,8 08C, 4h;c)P(OEt) 3 / toluene, 120 8C, 3h;d )AcOH,8 08C, 0.5-1.0 h, Ar atmosphere.Scheme4.Photooxidation reactions for 1c and 9.The structures of 10 and 11 were also determined by means of single-crystalX RD.Scheme5.Proposed reaction mechanism for the self-sensitized photooxidation of 1c'.The Gibbs free energies of 1c'(GS) and 3 O 2 are set to 0.0 kcal mol À1 as ar eference. IC = internal conversion, ISC = intersystem crossover, IM = intermediate, TS = transition state.

Recent Advances in Heterocyclic Nanographenes and Other Polycyclic Heteroaromatic Compounds

“…Applying their synthetic strategy toward the pyrazine-fused trichalcogenasumanenes 244.2 , Shao et al prepared a series of new D 1 –A–D 2 π-systems C22.1aa – bb consisting of the electron-donating tetrathiafulvalene (D 1 ) and trichalcogenasumanene (D 2 ) units connected through an electron-accepting pyrazine unit (A) ( Chart 22 ). 454 These compounds displayed a broad absorption band (λ = 450–720 nm) as a consequence of intramolecular charge transfer (ICT) transition contributed by both D 1 and D 2 . Femtosecond transient absorption (fs-TA) measurements were carried out under photoexcitation at λ = 385 nm.…”

Design, synthesis, and controllable transformation of bowl-shaped heterosumanenes

“…碗状共轭分子7具有良好的空穴 迁移率(μ h = 0.32 cm 2 V −1 s −1 ) [43] , 而勺状共轭分子42 则可用于制作光电晶体管(phototransistor)且表现出极 高的光响应性(photo sensitivity, 2.58×10 7 ) [44] . 基于化合 物20/40, 我们也成功地将四硫富瓦烯与杂化素馨烯通 图 12 磷元素和硫族元素共同杂化素馨烯的合成(网络版彩图) 图 13 基于硫族元素杂化素馨烯开环反应的荧光分子合成(网络版彩图) 邵向锋: 碗状共轭分子"杂化素馨烯"的设计合成及可控化学转化 过吡嗪单元融合, 形成了"给体-受体-给体"型勺状共轭 分子 [45] . 此类分子对单线态氧以及酸具有超高灵敏响 应, 而且在飞秒和皮秒时间尺度上具有不同的激发态 吸收.…”

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

“…The pyrazine-fused trichalcogenasumanenes have been assembled via the transformation of 1,2-dibutoxybenzene unit into the corresponding ortho -quinones by means of FeCl 3 in CH 2 Cl 2 /MeCN at room temperature ( Scheme 44 ) [ 79 – 81 ]. Interestingly, it was observed that 1,2-dibutoxy groups could be selectively transformed to the ortho -quinones in the presence of FeCl 3 .…”