The past few years witnessed extensive emergence of short-wavelength upconversion（UC） emission stimulated photoactivation studies. However, low efficiency of multi-photon process greatly limits further applications....The past few years witnessed extensive emergence of short-wavelength upconversion（UC） emission stimulated photoactivation studies. However, low efficiency of multi-photon process greatly limits further applications. Here, ultraviolet（UV） upconversion emissions originated from multi-photon process of Tm^3＋ were studied with Nd^3＋-sensitized NaGdF4：Yb,Tm@NaYF4：Nd,Yb core/shell nanoparticles. Crucial factors, including the contents of sensitizers Nd^3＋, Yb^3＋ and activator Tm^3＋, as well as the excitation power density were investigated based on the UV emission. Spectral results showed that high contents of Nd^3＋ in shell region up to 50%（molar fraction hereafter） and Yb^3＋ of 10% were essential to mediate the energy transfer via the core/shell interface and facilitate multi-photon UV emissions. Compared with segregated activator and sensitizer, a core/shell strategy with isolated Nd^3＋ in the shell was important for higher UV emission. Although the upconverting process was initiated with Nd^3＋→Yb^3＋, the short-wavelength emissions were intrinsically coming from four- and five-photon process. The optimized nanoparticles were found to be able to manipulate the configuration transition of azobenzene molecules, and it could be promising for near infrared（NIR） triggered optical switches applications.展开更多
Since the discovery of a surfactant directed self-assembly approach for the fabrication of mesoporous silica in 1992,increasing attention has been focused on the design and synthesis of mesostructured functional mater...Since the discovery of a surfactant directed self-assembly approach for the fabrication of mesoporous silica in 1992,increasing attention has been focused on the design and synthesis of mesostructured functional materials.Organic functionalization is becoming a major topic in this research field,since highly ordered mesostructured organic-inorganic hybrids offer novel functionalities and enhanced performance over their individual components.We begin with a brief overview of the three fundamental methods(post-synthetic grafting technique,co-condensation method,and preparation of periodic mesoporous organosilicas) for the preparation of organically functionalized mesostructured silica,and focus on one of the most promising approaches,which herein was named as functional-template directed self-assembly(FTDSA) approach,and in the eyes of the authors it has a special position in the preparation of this class of hybrid materials.A comprehensive overview of the state of research in the area of FTDSA and its potential applications will be given.展开更多
基金Project supported by National Natural Science Foundation of China(21425101,21331001,21371011)Ministry of Science and Technology of China(2014CB643800)
文摘The past few years witnessed extensive emergence of short-wavelength upconversion（UC） emission stimulated photoactivation studies. However, low efficiency of multi-photon process greatly limits further applications. Here, ultraviolet（UV） upconversion emissions originated from multi-photon process of Tm^3＋ were studied with Nd^3＋-sensitized NaGdF4：Yb,Tm@NaYF4：Nd,Yb core/shell nanoparticles. Crucial factors, including the contents of sensitizers Nd^3＋, Yb^3＋ and activator Tm^3＋, as well as the excitation power density were investigated based on the UV emission. Spectral results showed that high contents of Nd^3＋ in shell region up to 50%（molar fraction hereafter） and Yb^3＋ of 10% were essential to mediate the energy transfer via the core/shell interface and facilitate multi-photon UV emissions. Compared with segregated activator and sensitizer, a core/shell strategy with isolated Nd^3＋ in the shell was important for higher UV emission. Although the upconverting process was initiated with Nd^3＋→Yb^3＋, the short-wavelength emissions were intrinsically coming from four- and five-photon process. The optimized nanoparticles were found to be able to manipulate the configuration transition of azobenzene molecules, and it could be promising for near infrared（NIR） triggered optical switches applications.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 20821091 and 20771009)
文摘Since the discovery of a surfactant directed self-assembly approach for the fabrication of mesoporous silica in 1992,increasing attention has been focused on the design and synthesis of mesostructured functional materials.Organic functionalization is becoming a major topic in this research field,since highly ordered mesostructured organic-inorganic hybrids offer novel functionalities and enhanced performance over their individual components.We begin with a brief overview of the three fundamental methods(post-synthetic grafting technique,co-condensation method,and preparation of periodic mesoporous organosilicas) for the preparation of organically functionalized mesostructured silica,and focus on one of the most promising approaches,which herein was named as functional-template directed self-assembly(FTDSA) approach,and in the eyes of the authors it has a special position in the preparation of this class of hybrid materials.A comprehensive overview of the state of research in the area of FTDSA and its potential applications will be given.
