Chemiluminescence in the reaction of LnI2 (Ln = Dy, Nd) with water

Abstract

Сhemiluminescence (CL) upon the reaction of crystalline LnI 2 (Ln = Dy, Nd) with water was found. The CL emitters are the Ln 3+ * electron excited ions (Dy 3+ *, λ max = 470, 570 nm; Nd 3+ *, λ = 700-1200 nm) generated by the electron transfer from the Ln II ions to the H 2 O molecules. The identified reaction products are H 2 , dissolved LnI 3 , and insoluble LnI(OH) 2 (49-51% and 48-50% yield for DyI 2 and NdI 2 , respectively). The treatment of NdI 2 with an H 2 O solution in THF gives the NdI 2 OH(thf) 2 •3H 2 O complex and hydrogen.Chemiluminescence (CL) involving Ln II compounds, unlike Ln III compounds, was studied to less extent. The CL is known for the EuCl 2 complexes with organic ligands 1-3 and Cp 2 Yb, 4 Cp 2 Sm, and Cp 2 Eu lanthanido cenes (see Refs 5 and 6) upon oxidation with hydrogen peroxide and molecular oxygen. In all cases, the CL emit ters are the excited Ln 3+ * ions: Eu 3+ *, Yb 3+ *, and Sm 3+ *. The Eu II , Yb II , and Sm II compounds are rather stable, (E°(Ln 3+ /Ln 2+ ) = -(0.34-1.50 V) 7,8 ), whereas the compounds of other Ln II (Ln = Nd, Dy, and Tm) with very low oxidation potentials (E°(Ln 3+ /Ln 2+ ) = -(2.22-2.62 V) 7,8 ) are extremely unstable; they have been synthesized rather recently. 9-11 The properties of these compounds were studied to less extent, and their CL has not recently been examined. Therefore, investigation of the physicochemical properties of the labile Nd II and Dy II compounds is urgent.In this work, we studied for the first time the ability of DyI 2 (1) and NdI 2 (2) to enter chemical reactions and generate radiative excited states Ln 3+ *. The interaction of compounds 1 and 2 with water was chosen as this reac tion. The reaction has not been studied earlier: CL was not detected and no stable products were identified. ExperimentalCrystalline samples 1 and 2 (content of the main substance 95 and 93%, respectively) were synthesized according to earlier described procedures. 9,10 Bidistilled water was used; THF was purified by reflux over NaOH and metallic sodium and prior to use it was kept for 15 min over compound 1 or 2 for the addi tional purification from water traces.For recording IR spectra, the samples were prepared as a suspension in Nujol and placed between NaCl plates. Photolu minescence (PL) spectra were recorded on a home made spectrofluorimeter designed on the basis of an MDR 23 double monochromator. Absorption spectra were measured on Specord M 40 (UV visible region) and Specord M 40 (IR region) spec trophotometers.Chemiluminescence measurements. To measure the CL ki netics, a powder of compound 1 (18.20 mg, 0.04 mmol) or 2 (15.92 mg, 0.04 mmol) was placed under argon on the bottom of a glass cell mounted in a light tight chamber of the chemilumi nescence setup. 12 Water (2 mL) was added for 3 s from a doser to the cell, and CL was detected. The spectra of CL arisen upon the hydrolysis of compounds 1 (91.40 mg, 0.22 mmol) and 2 (87.60 mg, 0.22 mmol) were measured using a set of cut off color filters according to a known procedure 13 with FEU 39 (f...

Uncovering the Importance of Proton Donors in TmI2‐Promoted Electron Transfer: Facile CN Bond Cleavage in Unactivated Amides

“…This method was also applied to the first chemoselective reduction of esters with any lanthanide(II) reagent. [21] Initial mechanistic studies suggest that proton donors play a key role in activating the reagent [22] and that Tm III -bound ketyl radicals are more stable than the corresponding Sm III ketyls. [23] We fully expect that this work will serve as a platform to enable discovery of novel electrontransfer processes based on nonclassical lanthanide(II) iodides.…”

The first registration of a green liquid-phase chemiluminescence of the divalent Eu2+* ion in interaction of β-diketonate complexes Eu(acac)3·H2O, Eu(dpm)3, Eu(fod)3 and Eu(CH3COO)3·6H2O with Bui2AlH in THF with the participation of oxygen

“…These ions emit light from the UV to near-infrared region, spectrally manifested as narrow maximums, corresponding to the spin-forbidden f-f transitions. [2][3][4][5][6][7]10,12 At the same time, divalent lanthanide ions were not known as emitters and enhancers of CL in liquid-phase reactions before our studies, 13,14 although some of them, especially Eu 2+ , exhibit easily detected blue d-f photoluminescence (PL). [15][16][17][18][19][20][21][22][23] Only two years ago, we found very bright blue CL of the divalent Eu 2+ * ion, which was observed by the naked eye in the interaction of crystalline hydrate EuCl 3 $6H 2 O and diisobutylaluminum hydride Bu i 2 AlH in THF in the presence of oxygen.…”