IMRAM, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan.
J Phys Chem A. 2010 Apr 29;114(16):5242-50. doi: 10.1021/jp911177q.
Photoinduced multiple electron-transfer processes of a newly synthesized rotaxane with one acceptor and two donors are studied with the time-resolved fluorescence and absorption methods. In this rotaxane, zinc porphyrin (ZnP) with a crown-ether necklace is employed as a photosensitized electron donor; through the crown-ether, a short axle with C(60) and triphenylamine (TPA) at both terminals is penetrating as an electron acceptor and a hole-shift, respectively (abbreviated as (ZnP;C(60)-(A(S))-TPA)(Rot)). The time-resolved fluorescence and transient absorption measurements reveal that the through-space electron-transfer processes take place via the excited states of the ZnP unit to the spatially arranged C(60) moiety, giving the radical ion pair (ZnP(+);C(60)(-)-(A(S))-TPA)(Rot) in polar solvents. Consecutively, (ZnP;C(60)(-)-(A(S))-TPA(+))(Rot) is also generated by the through-space hole-shift between ZnP and TPA, in addition to the through-bond charge separation via the excited state of the C(60) moiety. Both radial ion pairs have lifetimes of 320-420 ns, which are longer than those of the previously reported similar rotaxane with cationic longer axle (150-170 ns).
用时间分辨荧光和吸收方法研究了一种新合成的轮烷的光诱导多电子转移过程，该轮烷带有一个受体和两个给体。在这个轮烷中，锌卟啉（ZnP）带有冠醚链，用作光敏电子给体；通过冠醚，一个带有 C(60)和两端的三苯胺（TPA）的短轴作为电子受体和空穴转移分别（简写为（ZnP；C(60)-(A(S))-TPA)(Rot)）。时间分辨荧光和瞬态吸收测量表明，通过空间电子转移过程发生在 ZnP 单元的激发态到空间排列的 C(60)部分，在极性溶剂中产生自由基离子对（ZnP(+);C(60)(-)-(A(S))-TPA)(Rot)）。此外，通过 C(60)部分的激发态进行的通过键电荷分离，除了通过空间空穴转移之外，还会产生（ZnP；C(60)(-)-(A(S))-TPA(+))(Rot)。两个径向离子对的寿命为 320-420 ns，长于以前报道的具有阳离子较长轴的类似轮烷（150-170 ns）。
