Steinebrunner David, Schnurpfeil Günter, Kohröde Mathis, Epp Alexander, Klangnog Khaetthariya, Tapia Burgos Jorge Adrian, Wichmann Andre, Wöhrle Dieter, Wittstock Arne
Institute of Applied and Physical Chemistry and Center for Environmental Research and Sustainable Technology, University Bremen Leobener Str. UFT 28359 Bremen Germany
MAPEX Center for Materials and Processes, University Bremen Bibliothekstr. 1 28359 Bremen Germany.
RSC Adv. 2020 Jun 17;10(39):23203-23211. doi: 10.1039/d0ra03891a. eCollection 2020 Jun 16.
Nanoporous gold powder was functionalized in a two-step approach by an azide terminated alkanethiol self-assembled monolayer (SAM) and a zinc(ii) phthalocyanine (ZnPc) derivative by copper catalyzed azide-alkyne cycloaddition (CuAAC). A series of different hybrid systems with systematic variation of the alkyl chain length on both positions, the alkanethiol SAM and the peripheral substituents of the ZnPc derivative, was prepared and studied in the photooxidation of diphenylisobenzofuran (DPBF). An enhancement by nearly one order of magnitude was observed for the photosensitized singlet oxygen (O) generation of the hybrid systems compared to the same amount of ZnPc in solution caused by the interaction of the npAu surface plasmon resonance and the excited state of the immobilized sensitizer. This interaction was shown to be distance dependent, with decreasing activity for short SAMs with alkyl chain lengths < 6 methylene groups caused by quenching of the excited state electron transfer as well as decreasing activity for SAMs with > 8 methylene groups due to decreasing energy transfer for long distances. An unexpected distance dependent behaviour was observed for the variation of the peripheral alkyl chain on the photosensitizer revealing a planar orientation of the immobilized photosensitizer on the nanoporous gold surface by a penta-coordinated central zinc ion through interaction with free azide groups from the self-assembled monolayer.
纳米多孔金粉通过两步法进行功能化修饰，首先通过叠氮基封端的链烷硫醇自组装单分子层（SAM），然后通过铜催化的叠氮化物-炔烃环加成反应（CuAAC）引入锌（II）酞菁（ZnPc）衍生物。制备了一系列不同的杂化体系，系统地改变了链烷硫醇SAM和ZnPc衍生物外围取代基两个位置上的烷基链长度，并研究了它们对二苯基异苯并呋喃（DPBF）的光氧化作用。与溶液中相同量的ZnPc相比，由于npAu表面等离子体共振与固定化敏化剂的激发态相互作用，杂化体系的光敏单线态氧（O）生成增强了近一个数量级。这种相互作用显示出与距离有关，对于烷基链长度小于6个亚甲基的短SAM，由于激发态电子转移猝灭导致活性降低；而对于亚甲基数大于8的SAM，由于长距离能量转移减少，活性也降低。对于光敏剂上外围烷基链的变化，观察到了意想不到的距离依赖性行为，这表明通过与自组装单分子层中的游离叠氮基团相互作用，固定化光敏剂通过五配位中心锌离子在纳米多孔金表面呈平面取向。
