Eu3+-modification of luminescent hybrid bimodal mesoporous silicas with various anions (NO3−, CH3COO−, and Cl−)

• Luminescent intensity of LHMS was enhanced by europium salts.
• Textural properties of LHMS were influenced by various anions.
• Effects of binding force and steric hindrance on luminescent performance were remarkable.

In order to enhance the intensity of luminescent hybrid bimodal mesoporous silica (LHMS), the rare earth Eu3+ ion was employed as an enhancer to modify 1,8-naphthalic anhydride (NA) molecules. The modified LHMS were prepared with various anions of europium salts including Cl−, NO3−, and CH3COO−. The structure and photoluminescence properties of the obtained samples were characterized by XRD, TEM, N2-adsorption/desorption, FT-IR, TGA, ICP-OES, and PL measurements. The results showed that the bimodal mesoporous system of BMMs could be preserved after functionalization via grafted Eu3+-modified NA molecules onto mesoporous matrix. However, the structure parameters and textural properties of resultant LHMS series were obviously influenced by the anions volume. Meanwhile, the luminescent performances of LHMS series were seriously impacted by both of the binding force between Eu3+ and various anions and steric hindrance of the anions, resulting in the intensity of emission peak of obtained LHMS series declining as following order: LHMS-EN (NO3−) > LHMS-EA (CH3COO−) > LHMS-EC (Cl−). Finally, the related mechanism was discussed in-depth.

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