Enhancement of the Luminescence Properties of Eu (III) Containing Paramagnetic Saponite Clays

Abstract

In this study, 1,10-phenanthroline molecules were introduced in the interlayer space of a paramagnetic synthetic saponite clay containing both Eu3+ and Gd3+ ions in structural positions. Two samples with different loading of phenanthroline dye were prepared. The resulting hybrid materials possessed improved optical emission properties due to an efficient antenna effect from the phenanthroline to the Eu3+ centers; this effect was demonstrated to be higher than the metal-to-metal Gd3+-Eu3+ energy transfer previously studied. Insights on the relaxometric properties in aqueous solution of the solids after incorporation of the antenna groups were also obtained through NMR relaxometric analyses.

Application of NMR relaxometry for real-time monitoring of the removal of metal ions from water by synthetic clays

“…58 The amount of captured elements depends on several factors: (i) the CEC of the solid, (ii) the charge and size of the metal cations and (iii) the diffusion process of the ions inside the clay galleries. 45–48,53,55…”

“…It is thus possible to avoid these disadvantages by using synthetic clays characterized by controlled morphology, particles size and physicochemical properties. 45–47 Recently, a synthetic saponite clay, belonging to the smectite family, has been studied for the recovery of lanthanide ions with different ionic radii (La 3+ , Gd 3+ and Lu 3+ ) from aqueous solutions, obtaining very encouraging results, especially if compared with commercial natural clays. 48 The uptake process was monitored by a conventional analytical technique, inductively coupled plasma optical emission spectroscopy (ICP-OES), which is widely used to quantify the metal concentration in different matrices.…”

Impregnation of Synthetic Saponites with Aldehydes: A Green Approach in the Intercalation of Bioactive Principles

“…For these reasons, synthetic saponites have attracted growing interest by the scientific community and novel derivative samples have been prepared and proposed for different scientific and technological applications, spanning from biomedicine [4,10,11] to catalysis [3,4,[12][13][14], together with environmental [4,[15][16][17][18] and energy-related purposes [3,4,19,20]. The physicochemical features of saponites can be modulated at three different levels: (1) modification of the composition, structure and morphology by varying the dilution of the synthesis gel in the hydrothermal synthesis [3][4][5]16,21] or by following alternative synthetic procedures based on sol-gel and microwave-assisted reactions [4,9,[22][23][24]; (2) introduction into the lamellae framework of metal ions, in order to confer specific properties to the final materials [4,[25][26][27][28][29][30][31][32]; (3) modification of the interlayer space of saponite, through intercalation of different chemical entities (i.e., ions, organic substances, metallo-chelates) [3,4,[33][34][35]<...…”