Relationship between interlayer anions and photoluminescence of layered rare earth hydroxidesElectronic supplementary information (ESI) available: Additional XRD patterns and FT-IR spectra of Gd1.80RE0.20(OH)5X·nH2O (LGdH:RE) where RE = Eu, Tb, and Ce and X = NO3−, F−, Cl−, I−, OH−, ClO3−, S2−, CO32−, SO42−, terephthalate, 2-naphthoate, and dodecylsulfate. XRD patterns measured as a function of reaction time during the exchange reaction of Gd1.80Ce0.20(OH)5NO3·nH2O with Cl− and vice versa. See D

• Main Authors: Kim, Hyunsub, Lee, Byung-Il, Jeong, Heejin, Byeon, Song-Ho
• Format: Article
• Language: English
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/c5tc01339a

The effect of interlayer anions on the photoluminescence of layered rare earth hydroxides was investigated with the rare earth (RE)-doped layered gadolinium hydroxynitrate as a representative base matrix for efficient and stable anion-exchange reactions. Eu 3+ , Tb 3+ , and Ce 3+ were employed as RE activator ions for red, green, and blue emissions, respectively. The excitation and emission behaviors of Gd 1.80 RE 0.20 (OH) 5 X· n H 2 O (LGdH:RE) were systematically compared for various interlayer inorganic and organic anions, where X = F − , Cl − , I − , OH − , ClO 3 − , S 2− , CO 3 2− , SO 4 2− , terephthalate, 2-naphthoate, and dodecylsulfate members were obtained by the exchange reaction of corresponding X = NO 3 − members. Interestingly, a close relationship was found between the UV-Vis absorption spectra of aqueous solutions containing X anions and the excitation behavior of LGdH:RE. Thus, NO 3 − , I − , and S 2− anions showing high absorbance in aqueous solution consistently shielded the excitation light for the 8 S 7/2 → 6 I J transition of Gd 3+ and the 4f → 5d interconfigurational transitions of Tb 3+ and Ce 3+ to turn off the corresponding emissions from LGdH:Eu, LGdH:Tb, and LGdH:Ce. In contrast, the effect of terephthalate and 2-naphthoate, despite high absorbance in aqueous solutions, was significantly different depending on the RE activator ion. It is proposed that an identical interlayer anion in the gallery of LRHs can filter or sensitize the UV energy for excitation of RE 3+ -doped LRHs and its role (whether as a filter, a sensitizer, or just a spacer) is determined by the nature of activator ions. The effect of interlayer anions on the photoluminescence of layered rare earth hydroxides was investigated with Eu 3+ , Tb 3+ , and Ce 3+ -doped layered gadolinium hydroxynitrate as a representative base matrix for efficient and stable anion-exchange reactions.