Studies on photo-driven logic molecular devices with fast response

1.基于混价络合物的电荷转移型逻辑器件当Ru(II)-Os(III)与四苯并吩嗪桥联的混价络合物被光照射时，观察到电子从Ru(II)部分的MLCT态向Os(III)部分的转移发生，时间常数为20ps，效率高(Ф~1)。生成的产物态--Ru(III)-Os(II)混价异构体的寿命大于100 ns。由于在该配合物中观察到的两个准稳定态Ru(II)-Os(III)和Ru(III)-Os(II)可视为逻辑状态，分别为‘0’和‘1’，我们认为该配合物将作为光驱动触发器分子，具有很快的响应(~100 GHz)。然而，1态，即Ru(III)-Os(II)的辐照，并不能有效地产生0态。该分子的量子力学计算表明，(^3CT)Ru(II)-Os(III)和Ru(III)-(^3CT)Os(II)这两个MLCT态相互作用很强，以至于两个MLCT态之间的势垒不足以使它们局域化。DNA分子探针的光开关机理为了阐明Ru(II)dppz(dppz=dipyridophenazine)的光开关机理，测量了不同dppz衍生物的Ru(II)的发光性质。结果表明，两个MLCT态之间的溶剂化能只有100 meV的差异就可以使发射峰能量发生切换。这种尖锐的跃迁是造成两个MLCT态(~65 meV)之间电子相互作用异常弱的主要原因。

1. Charge-transfer type logic devices based on mixed-valence complexesWhen Ru(II)-Os(III) mixed-valence complex bridged with tetrapyridophenazine was photoirradiated, it was observed that electron transfer from MLCT state of Ru(II) moiety to Os(III) moiety occurs with time constant of 20 ps and with high efficiency (Ф〜1). The lifetime of the resultant product state, Ru(III)-Os(II) mixed-valence isomer state, was longer than 100 ns. Since two pseudo-stable states, Ru(II)-Os(III) and Ru(III)-Os(II), observed in this complex can be regarded as logical state, '0' and '1', respectively, we thought that this complex would work as photo-driving flip-flop molecule with very fast response (〜100GHz). However, the irradiation of '1' state, i.e., Ru(III)-Os(II), did not give '0' state, efficiently. The quantum mechanical calculation of this molecule indicated that two MLCT states, i.e., (^3CT)Ru(II)-Os(III) and Ru(III)-(^3CT)Os(II), so strongly interact each other that the barrier between the two MLCT states was not high enough to allow them to be localized.2. The mechanism of light-switching of DNA molecular probeTo clarify the mechanism of light-switching in Ru(II) dppz (dppz=dipyridophenazine) which is known to be an excellent DNA probe, the emission properties were measured for Ru(II) of various dppz derivatives. It is found out that only 100meV difference in solvation energy for between two MLCT states can switch the emission peak energy. Such sharp switching is mainly responsible for the unusually weak electronic interaction between two MLCT states (〜65 meV).