Sani Umar, Alatawi Omar M, Halawani Nuha M, Gould Jamie A, Knight Julian G, Cucinotta Fabio
School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom.
Department of Chemistry, Faculty of Applied Science, Umm Al-Qura University, Makkah, Saudi Arabia.
Front Chem. 2022 Jun 28;10:921112. doi: 10.3389/fchem.2022.921112. eCollection 2022.
This study presents the design and characterization of new monochromatic light-harvesting systems based on inorganic porous materials hybridized with organic dye molecules within their structure. A new fluorescent BOPHY dye was prepared, characterized optically and used as both reference and synthetic precursor for two alkoxysilane derivatives that were incorporated separately within a silica structure. The dyes, one bearing one alkoxysilane group and the other one two, were co-condensed with tetraethyl orthosilicate to form a hybrid organo-silica framework, where they are found at specific locations. The structure of the new materials was analysed by powder XRD and TEM, which confirmed the presence of the hexagonal pore arrangement typical of mesoporous MCM-41 silica particles. The steady-state and time-resolved analysis showed that the particles where the dyes are most dispersed within the framework retain the highest fluorescence quantum yield, up to 0.63, in the green-yellow region of the visible spectrum. On the other hand, increasing the content of BOPHY units in the solid matrix seem to favour non-radiative deactivation pathways and aggregation phenomena, which lower the efficiency of light emission. The materials also exhibit interesting properties, such as a dual excited-state decay and fluorescence anisotropy. The short fluorescence lifetime, about 2 ns, matches the typical singlet lifetime of BOPHY dyes, whereas the long component, up to 20 ns, is attributed to delayed fluorescence, which could take place via charge recombination. Optical anisotropy experiments revealed that all materials show polarised light emission to a significant extent and, for most samples, it was also possible to determine a polarisation transfer decay trace, from 400 to 800 ps This is ascribed to the occurrence of energy migration between neighbouring dye units within the silica structure.
本研究介绍了基于无机多孔材料与结构内有机染料分子杂化的新型单色光捕获系统的设计与表征。制备了一种新型荧光BOPHY染料，对其进行了光学表征，并用作两种分别引入二氧化硅结构中的烷氧基硅烷衍生物的参考和合成前体。这两种染料，一种带有一个烷氧基硅烷基团，另一种带有两个烷氧基硅烷基团，与正硅酸四乙酯共缩合形成杂化有机硅骨架，它们位于特定位置。通过粉末XRD和TEM分析了新材料的结构，证实了介孔MCM-41二氧化硅颗粒典型的六边形孔排列的存在。稳态和时间分辨分析表明，染料在骨架中分散最均匀的颗粒在可见光谱的黄绿区域保持最高的荧光量子产率，高达0.63。另一方面，增加固体基质中BOPHY单元的含量似乎有利于非辐射失活途径和聚集现象，从而降低发光效率。这些材料还表现出有趣的性质，如双激发态衰减和荧光各向异性。短荧光寿命约为2 ns，与BOPHY染料的典型单线态寿命相匹配，而长成分高达20 ns，归因于延迟荧光，这可能通过电荷复合发生。光学各向异性实验表明，所有材料在很大程度上都表现出偏振光发射，对于大多数样品，还可以确定从400到800 ps的偏振转移衰减轨迹。这归因于二氧化硅结构内相邻染料单元之间发生的能量迁移。
