[Effect of inorganic host MCM-41 doped with Yb3+ on the photoluminescence properties of guest Tb(aspirin) 3phen].

Assembly system with MCM-41 doped with Yb 3+ as a host,and Tb(aspirin) 3phen,which had been heat treated,as an active optical guest,was synthesized at room temperature.The structure and physical properties of the composites were characterized by a combination of different techniques such as XRD,N 2 adsorption-desorption and IR,while the photoluminescence properties of the composites were analyzed by PL.Excitation and emission spectra were examined to explore the PL properties of the prepared samples and the relationship between the optical guest and the inorganic host.The present paper reports a new synthesis method called "Direct-Calcination" to avoid the loss of rare earth ions in the process of synthesis.Strong reflections at 2 θ =2.6 attributed to(100) reflection were presented in XRD patterns of both Yb/MCM-41 and Tb(aspirin) 3phen-Yb/MCM-41,which always can be observed for regular,spherical structure of MCM-41 materials,and the inorganic framework order increased after Tb(aspirin) 3phen being incorporated into the channels of Yb/MCM-41.The intensity of the band at 963 cm-1 decreased in IR spectrum of Yb/MCM-41,relative to that in IR spectrum of MCM-41,implying that Yb 3+ had been banded with the framwork.And a sharp band at 1 384 cm-1 in IR spectrum of Tb(aspirin) 3phen-Yb/MCM-41 also gives the characteristic information about the bands in Tb(aspirin) 3phen-MCM-41.The results from the characterization of PL show that the wide excitation band over 240-375 nm of Tb(aspirin) 3phen is assigned to the carbonyl group n→π transition absorption,benzene ring π→π transition absorption of aspirin,and phenanthrene absorption of phen.The luminescence intensity of Tb(aspirin) 3phen incorporated into the channels of MCM-41 can be enhanced by heat treating in the synthesis process of Tb(aspirin) 3phen,while the intensity also can further increases by doping Yb 3+ in the silicon framework of MCM-41.The luminescence intensity of the assembly system gets to maximum when Yb/Si ratio is 7.579×10 -3.