利用Nafion薄膜-水溶液界面提高铂络合物和紫精间的光致电荷分离态的寿命(英文)

ENHANCEMENT OF PHOTOINDUCED CHARGE SEPARATION IN CYCLOMETALLATED PLATINUM(Ⅱ) COMPLEX-VIOLOGEN SYSTEM VIA NAFION MEMBRANE-SOLUTION INTERFACE

研究了铂络合物PtL1 L2 2 +(L1 =4 甲氧基苯基 6 苯基 2 ,2’ 联吡啶 ,L2 =吡啶 )和磺酸丙基紫精 (PVS0 )在Nafion膜中进行的光致电子转移和电荷分离 .Nafion膜被水溶胀后形成类似反胶束的结构 ,其空腔表面带有负电荷 .将带有正电荷的电子给体PtL1 L2 2 +吸附到膜中 ,电中性的受体PVS0 溶于水中 ,采用带有正电荷的N ,N’ 四亚甲基 2 ,2’ 联吡啶 (DQ2 +)作为电荷载体 ,并且也被吸附到膜内 .激发PtL1 L2 2 +导致与DQ2 +发生电子转移 ,生成的DQ+· 迁移到Nafion膜 水溶液界面并将电子传给受体PVS0 ,生成的PVS+·被Nafion膜表面负电荷排斥从而阻止电荷回传 .电子转移产物PtL1 L2 3 +位于膜中 ,PVS+·位于溶液中 ,两者隔离 ,电荷分离状态的寿命可长达几天 .

The photoinduced electron transfer from the excited state of cyclometallated platinum(Ⅱ) complex PtL 1L 2 2+ (L 1=4 methoxyphenyl 6 phenyl 2,2' bibyridine,L 2=pyridine) incorporated into Nafion membranes to propylviologen sulfonate(PVS 0) in the surrounding solution has been examined by photochemical measurements.N,N' tetramethylene 2,2' bipyridinium(DQ 2+ ) entrapped in the Nafion membranes is used as an electron relay.Luminescence quenching studies indicate that the quenching reaction of PtL 1L 2 2+ with DQ 2+ is both of dynamic and static nature.PtL 1L 2 3+ generated from the luminescence quenching remains in the Nafion matrix,while DQ +· migrates by an electron hopping mechanism to the Nafion water interface,where transfers an electron to PVS 0 to produce PVS -· .The negative charged PVS -· is repelled into the bulk solution by the anionic Nafion surface.The isolation of the photoinduced oxidized species PtL 1L 2 3+ in Nafion from the ultimate reduced species PVS -· in solution prevents them from undergoing back electron transfer,and a long lived(up to a few days) charge separation state is achieved.