Interaction of Rare-Earth Metals and Some Perfluorinated β-Diketones

Abstract

In this work, we demonstrate the fundamental relationships between stability constants and periodic, acid–base, and structural parameters for complexes of some 1,3-diketones. The four analogues of hexafluoroacetylacetone2-thenoyltrifluoroacetone, 2-furoyltrifluoroacetone, benzoyltrifluoroacetone, and 2-naphthyltrifluoroacetonehave been studied as chelating ligands for 16 rare-earth metals (Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) in aqueous solutions. Systems have been investigated spectrophotometrically using a multiwave nonlinear least-squares regression algorithm for data processing. Conditional stability constants were obtained for a wide pH region (2.0–5.4) at constant ionic strength (I = 0.5 M, NaCl). To receive the apparent (“true”) equilibrium parameters, acid–base and keto–enol characteristics of the studied ligands have been described and revised for specific conditions. Dissociation constants were obtained in citrate–phosphate buffer media and protonation parameters were received in concentrated hydrochloric acid by the Cox–Yates method. The apparent formation constants for monocomplex species were obtained as thermodynamic invariants (depend only on the temperature) for each ligand and lie from 4.2 to 12.7 logarithmic units. Although the studied ligands have similar values of pK a, the stabilities of their complexes vary considerably. Systematic analysis of 64 apparent stability constants demonstrates that the force of interaction between the metals and nonsymmetric β-diketones increases as 2-furoyltrifluoroacetone < 2-thenoyltrifluoroacetone < benzoyltrifluoroacetone < 2-naphthyltrifluoroacetone. The studied ligands display varying degrees of the correlation between the periodic parameters and formation constants. Naphthyltrifluoroacetone and its complexes with heavy lanthanides exhibit a clear trend in properties with increasing ionic potential. In general, the received set of data can be described from purely electrostatic grounds within the framework of the periodic law. Spectral, keto–enol, acid–base, and complexing properties were reproduced using density functional theory modeling and explain some of the regularities discovered.

Visual Monitoring of Levofloxacin in Biofluids by Europium(III)-Functionalized Mesoporous Silica Nanoparticles

“…When the excited triplet energy level of the ligand is higher than the 5 D 0 energy level of Eu, the energy transfer from ligand to Eu 3+ may occur and the fluorescence of Eu 3+ can be sensitized, which is called the “antenna effect” . It is reported that LVFX includes the β-diketone moiety which has a strong coordination ability with Eu 3+ . , When LVFX is added to free Eu 3+ , the fluorescence of Eu 3+ + LVFX is still weak, indicating that LVFX cannot replace water molecules coordinating with Eu 3+ and the ineffective energy transfer from LVFX to Eu 3+ (Figure A). However, the addition of LVFX into Eu@Am-MSNs causes great enhancement of red emission from Eu (Figure B).…”

“…54 It is reported that LVFX includes the β-diketone moiety which has a strong coordination ability with Eu 3+ . 55,56 When LVFX is added to free Eu 3+ , the fluorescence of Eu 3+ + LVFX is still weak, indicating that LVFX cannot replace water molecules coordinating with Eu 3+ and the ineffective energy transfer from LVFX to Eu 3+ (Figure 5A). However, the addition of LVFX into Eu@Am-MSNs causes great enhancement of red emission from Eu (Figure 5B).…”

Highly Tunable 4-Phosphoryl Pyrazolone Receptors for Selective Rare-Earth Separation

“…Yield: 0.45 g (18%); mp 101−103 °C; Raman (80 mW, in cm −1 ) ν: 3074 (38), 3064 (42), 3035 (15), 2987 (16), 2958 (46), 2923 (42), 2858 (35), 1598 (100), 1550 (9), 1527 (27), 1492 (13), 1438 (45), 1400 (32), 1371 (19), 1325 (22), 1300 (9), 1180 (6), 1161 (20), 1051 (10), 1024 (14), 1010 (11), 999 (61), 850 (15), 715 (9), 642 (18), 615 (15), 436 (6), 266 (6), 247 (6), 148 (11), 117 (13), 75 (74); IR (ATR, in cm −1 ) ν: 2955 (vw), 2856 (vw), 2490 (vw), 1599 (w), 1549 (m), 1531 (m), 1491 (w), 1460 (w), 1437 (w), 1400 (w), 1369 (vw), 1325 (w), 1298 (vw), 1265 (vw), 1188 (s), 1165 (m), 1092 (w), 1070 (w), 1051 (w), 1011 (vs), 924 (vw), 833 (w), 804 (vs), 768 (s), 712 (m), 692 (s), 654 (w), 642 (vw), 607 (m), 552 (vs), 511 (m), 434 (m); 1 H NMR (CDCl 3 , 300 K, in ppm): δ 2.26 (3H, d, 4 J HP = 0.8 Hz, H4), 3.76 (6H, d, 3 J HP = 11.7 Hz, H5), 7.28 (1H, mt, 3 J HH = 7.5 Hz, H10), 7.43 (2H, mt, 3 J HH = 8.0 Hz, H9), 7.77 (2H, md, 3 J HH = 7.6 Hz, H8); 13 C{ 1 H} NMR (CDCl 3 , 300 K, in ppm): δ 14.0 (1C, s, C4), 52.9 (2C, d, 2 J CP = 5 Hz, C5), 82.6 (1C, d, 1 J CP = 219 Hz, C2), 121.5 (2C, s, C8), 126.8 (1C, s, C10), 129.2 (2C, s, C9), 137.8 (1C, s, C7), 149.6 (1C, d, 2 J CP = 10 Hz, C3), 159.8 (1C, d, 2 J CP = 23 Hz, C1); 31 (2-ethylhexyl)(5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)phosphonate HL 3 .…”

“…Yield: 0.12 g (4%); mp 113−115 °C; Raman (255 mW, in cm −1 ) ν: 3068 (100), 3031 (16), 2937 (30), 1597 (54), 1502 (15), 1406 (18), 1371 (13), 1280 (14), 1222 (12), 1006 (30), 87 (36), 75 (32), 63 (39), 52 (66); IR (ATR, in cm −1 ) ν: 3064 (vw), 2924 (vw), 2785 (vw, br), 2586 (vw), 1626 (w), 1591 (w), 1549 (w), 1500 (w), 1487 (m), 1458 (w), 1400 (w), 1369 (vw), 1352 (vw), 1311 (w), 1281 (vw), 1252 (w), 1209 (w), 1186 (m), 1159 (w), 1072 (vw), 1022 (vw), 930 (w), 914 (m), 897 (m), 839 (w), 773 (m), 764 (m), 742 (w), 725 (w), 710 (w), 687 (m), 625 (vw), 615 (vw), 588 (w), 563 (w), 548 (w), 530 (w), 513 (w), 492 (w), 484 (w); 1 H NMR (CDCl 3 , 300 K, in ppm): δ 2.37 (3H, s, H4), 7.20 (2H, t, 3 J HH = 7.2 Hz, H8), 7.23 (4H, d, 3 J HH = 7.8 Hz, H6), 7.28 (1H, t, 3 J HH = 7.5 Hz, H13), 7.35 (4H, t, 3 J HH = 7.8 Hz, H7), 7.42 (2H, t, 3 J HH = 7.8 Hz, H12), 7.74 (2H, d, 3 J HH = 8.0 Hz, H11); 13 recently, and the characterization data was also reported. 69 HL 8 was recently reported by our group, and its preparation was reproduced in this work.…”

“…13,26 Various extractants have been investigated for the separation of REEs in LLE processes. Organophosphorus compounds such as di-(2-ethylhexyl)phosphoric acid (D2EHPA, P204), 1,13, [EHP], P507), 13,28,29 bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex 272), 12 tributyl phosphate (TBP), 30 trioctylphosphine oxide (TOPO), 31 β-diketones such as benzoyl-1,1,1-trifluoroacetone and 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione, 32 primary amines such as tri-alkyl methylamine, and quaternary amines such as tri-octyl methylammonium nitrate (Aliquat 336) have all been widely investigated. 11 Among these, organophosphorus compounds, such as D2EHPA, HEH[EHP], and Cyanex 272, are the most widely employed for REE separation.…”