Schneider Johannes, Kollhoff Fabian, Bernardi Johannes, Kaftan Andre, Libuda Jörg, Berger Thomas, Laurin Mathias, Diwald Oliver
Department of Materials Science and Physics, Paris Lodron University of Salzburg , Hellbrunnerstrasse 34/III, A-5020 Salzburg, Austria.
Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg , Egerlandstraße 3, 91058 Erlangen, Germany.
ACS Appl Mater Interfaces. 2015 Oct 21;7(41):22962-9. doi: 10.1021/acsami.5b08123. Epub 2015 Oct 12.
Molecular insights into porphyrin adsorption on nanostructured metal oxide surfaces and associated ion exchange reactions are key to the development of functional hybrids for energy conversion, sensing, and light emission devices. Here we investigated the adsorption of tetraphenyl-porphyrin (2HTPP) from toluene solution on two types of MgO powder. We compare MgO nanocubes with an average size d < 10 nm and MgO cubes with 10 nm ≤ d ≤ 1000 nm. Using molecular spectroscopy techniques such as UV/vis transmission and diffuse reflectance (DR), photoluminescence (PL), and diffuse reflectance infrared Fourier-transform (DRIFT) spectroscopy in combination with structural characterization techniques (powder X-ray diffraction and transmission electron microscopy, TEM), we identified a new room temperature metalation reaction that converts 2HTPP into magnesium tetraphenyl-porphyrin (MgTPP). Mg(2+) uptake from the MgO nanocube surfaces and the concomitant protonation of the oxide surface level off at a concentration that corresponds to roughly one monolayer equivalent adsorbed on the MgO nanocubes. Larger MgO cubes, in contrast, show suppressed exchange, and only traces of MgTPP can be detected by photoluminescence.
对卟啉在纳米结构金属氧化物表面的吸附及相关离子交换反应的分子层面见解，是开发用于能量转换、传感和发光器件的功能杂化材料的关键。在此，我们研究了四苯基卟啉（2HTPP）从甲苯溶液在两种类型氧化镁粉末上的吸附情况。我们比较了平均尺寸d < 10 nm的氧化镁纳米立方体和10 nm ≤ d ≤ 1000 nm的氧化镁立方体。使用紫外/可见透射和漫反射（DR）、光致发光（PL）以及漫反射红外傅里叶变换（DRIFT）光谱等分子光谱技术，并结合结构表征技术（粉末X射线衍射和透射电子显微镜，TEM），我们确定了一种新的室温金属化反应，该反应将2HTPP转化为四苯基卟啉镁（MgTPP）。氧化镁纳米立方体表面的Mg(2+)吸收以及氧化物表面随之发生的质子化在一个浓度处趋于平稳，该浓度大致对应于吸附在氧化镁纳米立方体上的一个单层当量。相比之下，较大的氧化镁立方体显示出交换受到抑制，并且通过光致发光只能检测到痕量的MgTPP。
