Theoretical Modeling (Sparkle RM1 and PM7) and Crystal Structures of the Luminescent Dinuclear Sm(III) and Eu(III) Complexes of 6,6,7,7,8,8,8- Heptafluoro-2,2-dimethyl-3,5-octanedione and 2,3-Bis(2-pyridyl)pyrazine: Determination of Individual Spectroscopic Parameters for Two Unique Eu³⁺ Sites

Abstract

Heteroleptic homo dinuclear complexes [Sm(fod) 3 (μ-bpp)Sm(fod) 3 ] and [Eu(fod) 3 (μ-bpp)Eu(fod) 3 ] and their diamagnetic analogue [Lu(fod) 3 (μ-bpp)Lu(fod) 3 ] (fod is the anion of 6,6,7,7,8,8,8- heptafluoro-2,2-dimethyl-3,5-octanedione (Hfod) and bpp is 2,3-bis(2-pyridyl)pyrazine) are synthesized and thoroughly characterized. The lanthanum gave a 1:1 adduct of La(fod) 3 and bpp with the molecular formula of [La(fod) 3 bpp]. The 1 H NMR and 1 H- 1 H COSY spectra of the complexes were used to assign the proton resonances. In the case of paramagnetic Sm 3+ and Eu 3+ complexes, the methine (of the fod moiety) and the bpp resonances are shifted in the opposite direction and the paramagnetic shifts are dipolar in nature, which decrease with increasing distance of the proton from the metal ion. The single-crystal X-ray analyses reveal that the complexes (Sm 3+ and Eu 3+ ) are dinuclear and crystallize in the triclinic P 1 space group. Each metal in a given complex is eight coordinate by coordinating with six oxygen atoms of three fod moieties and two nitrogen atoms of the bpp. Of the two metal centers, in a given complex, one has a distorted square antiprism arrangement and the other acquires a distorted dodecahedron geometry. The Sparkle RM1 and PM7 optimized structures of the complexes are also presented and compared with the crystal structure. Theoretically observed bond distances are in excellent agreement with the experimental values, and the RMS deviations for the optimized structures are 2.878, 2.217, 2.564, and 2.675 Å. The photophysical properties of Sm 3+ and Eu 3+ complexes are investigated in different solvents, solid, and PMMA-doped thin hybrid films. The spectroscopic parameters (the Judd–Ofelt intensity parameters, radiative parameters, and intrinsic quantum yield) of each Eu 3+ sites are calculated using the overlap polyhedra method. The theoretically obtained parameters are close to the experimental results. The lifetime of the excited state is 38.74 μs for Sm 3+ and 713.62 μs for the Eu 3+ complex in the solid state.

Pure red-light emitting europium based complexes as efficient UV light converters: synthesis, crystal structure and photoluminescence properties

“…highest-density packing in the crystal structure. 19 The average Eu-O (fod) and Eu-N bond lengths in complexes 2 and 3 are in agreement with those in other reported Eu ternary complexes, [Eu(fod) 3 ( phen)], 25 [Eu(hfaa) 3 (indazole) 3 ], 21 [Eu(fod) 3 (μ-bpp)Eu(fod) 3 ], 14 [Eu(hfa) 3 (bpyO 2 )], 19 [Eu(hfa) 3 (bpy) (H 2 O)] 26 and [Eu(hfa) 3 27…”

Optical, electrochemical and photophysical analyses of heteroleptic luminescent Ln(iii) complexes for lighting applications

“…Emission profiles show characteristic peaks of at 564 nm ( 04 G 5/2 → 06 H 5/2 ), 601 nm ( 4 G 5/2 → 6 H 7/2 ), 648 nm ( 4 G 5/2 → 6 H 9/2 ) and 707 nm ( 4 G 5/2 → 6 H 11/2 ) transition. 57,58 Ligand dependent bands were appeared in emission spectra of S3 and S4 . The emission spectra of S1–S4 evident most pronounced peak at 648 nm depends on the coordinating surrounding of Sm 3+ ion.…”

Ionic Liquid Assisted Exothermic Complexation of Trivalent Lanthanides with Fluorinated β Diketone: Multitechnique Approach with Theoretical Insight

“…Eu­(TTA) 3 Phen, Eu­(TTA) 3 Pehn 0.1 PMO, Eu­(TTA) 2 (Phen)­AA (Phen: phenanthroline, AA: acrylic acid, MA: methacrylic acid, PMO: periodic mesoporous organosilica) . The binuclear Eu-HFOD complex showed solvent-dependent Ω 2 and Ω 4 values ranging from 23.33 × 10 –20 −20.39 × 10 –20 for Ω 2 and 2.45 × 10 –20 −3.07 × 10 –20 for Ω 4 in a variety of solvents including acetone, chloroform, dichloromethane, ethanol, etc . Diglycolamide functionalized calix[4]­arenes and pillararenes exhibited J–O constants from 4.03 × 10 –20 –4.48 × 10 –20 and 4.95 × 10 –20 –5.76 × 10 –20 , respectively, while that for CMPO (carbamoyl methyl phenyl phosphine oxide) functionalized ligands were 4.66 × 10 –20 −6.82 × 10 –20 and 4.30 × 10 –20 −5.49 × 10 –20 , respectively. ,, J–O parameters for TODGA, CMPO, DMDBTDMA, and TRPO in n -dodecane were reported to be 5.19 × 10 –20 and 2.73 × 10 –20 ; 5.28 × 10 –20 and 7.07 × 10 –20 ; 2.4 × 10 –20 and 2.46 × 10 –20 ; 8.99 × 10 –20 and 3.80 × 10 –20 , respectively .…”

“…The ligand, 6,6,​7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione (HFOD), is one such fluorinated β diketone known for its ease of synthesis, higher stability, and good luminescent properties due to the replacement of high energy N–H/C–H vibration by low energy C–F bonds . Heteroleptic homo binuclear complexes of trivalent actinides with HFOD have been recently investigated by crystal structure, luminescence, and theoretical computation . Stoichiometrically controlled, seven and eight coordinated Sm 3+ , Eu 3+ , and Tb 3+ complexes of Hfod have been reported for the comparative evaluation of their luminescence properties .…”

“…2 Heteroleptic homo binuclear complexes of trivalent actinides with HFOD have been recently investigated by crystal structure, luminescence, and theoretical computation. 3 Stoichiometrically controlled, seven and eight coordinated Sm 3+ , Eu 3+ , and Tb 3+ complexes of Hfod have been reported for the comparative evaluation of their luminescence properties. 4 HFOD-based binuclear complexes of trivalent lanthanides bridged by bipyrimidine have also been reported in the literature.…”