Larowska Daria, Wojcik Aleksandra, Mazurkiewicz-Pawlicka Marta, Malolepszy Artur, Stobiński Leszek, Marciniak Bronislaw, Lewandowska-Andralojc Anna
Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, Poznan, 61-614, Poland.
Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstraße 400, 01328, Dresden, Germany.
Chemphyschem. 2019 Apr 16;20(8):1054-1066. doi: 10.1002/cphc.201900040. Epub 2019 Mar 28.
Non-covalent nanohybrids composed of cationic 5,10,15,20-tetra(4-trimethylammoniophenyl)porphyrin tetra(p-toluenesulfonate) (TMAP) and the graphene oxide sheets were prepared under two pH values (6.2 vs. 1.8). The TMAP molecule was positively charged, regardless of the pH value during preparation. However, protonation of the imino nitrogens increased the overall charge of the porphyrin molecule from +4 to +6 (TMAP and TMAP ). It was found that at acidic pH, interaction of TMAP with GO was largely suppressed. On the other hand, results of FTIR, Raman spectroscopy, thermogravimetric analysis, atomic force microscopy (AFM) and elemental analysis confirmed effective non-covalent functionalization of graphene oxide with cationic porphyrin at pH 6.2. The TMAP -GO hybrids exhibited well defined structure with a monolayer of TMAP on the GO sheets as confirmed by AFM. Formation of the ground-state TMAP -GO complex in solution was monitored by the red-shift of the porphyrin Soret absorption band. This ground-state interaction between TMAP and GO is responsible for the static quenching of the porphyrin emission. Fluorescence was not detected for the nanohybrid which indicated that a very fast deactivation process had to take place. Ultrafast time-resolved transient absorption spectroscopy clearly demonstrated the occurrence of electron transfer from the photoexcited TMAP singlet state to GO sheets, as proven by the formation of a porphyrin radical cation.
由阳离子型5,10,15,20-四（4-三甲基铵苯基）卟啉四（对甲苯磺酸盐）（TMAP）和氧化石墨烯片组成的非共价纳米杂化物是在两个pH值（6.2对1.8）下制备的。无论制备过程中的pH值如何，TMAP分子都带正电荷。然而，亚氨基氮的质子化使卟啉分子的总电荷从 +4增加到 +6（TMAP和TMAP ）。研究发现，在酸性pH值下，TMAP与GO的相互作用受到很大抑制。另一方面，傅里叶变换红外光谱（FTIR）、拉曼光谱、热重分析、原子力显微镜（AFM）和元素分析的结果证实了在pH 6.2时阳离子卟啉对氧化石墨烯的有效非共价功能化。如AFM所证实的，TMAP-GO杂化物呈现出明确的结构，在GO片上有单层的TMAP。通过卟啉Soret吸收带的红移监测溶液中基态TMAP-GO复合物的形成。TMAP和GO之间的这种基态相互作用导致了卟啉发射的静态猝灭。未检测到纳米杂化物的荧光，这表明必须发生非常快速的失活过程。超快时间分辨瞬态吸收光谱清楚地证明了从光激发的TMAP单重态到GO片的电子转移的发生，卟啉自由基阳离子的形成证明了这一点。
