Solvoluminescence of Cerium(III) Thiocyanate Complex

Abstract

Ac erium(III) thiocyanate complex shows brightblue emission at approximately 450 nm in acetonitrile, the quantumy ield of which reaches more than 40 %a t2 98 K. Non-coordinating solvents such as acetonitrile give blue emission whereas oxygen-coordinatinga nd nitrogen-coordinatings olvents afford near UV and green emissions, respectively.Supporting information and the ORCID identification number(s) for the author(s) of this articlecan be found under: https://doi.Figure 3. Emission spectra of the Ce III complex, composed of Ce(OTf) 3 and nBu 4 NSCN (1:3 molar ratio), in the representatives olvents; methanol (red, l ex = 267 nm), chloroform (cyan, l ex = 333 nm),t etrahydrofuran (yellow, l ex = 343 nm), acetonitrile (black, l ex = 365 nm), toluene (purple, l ex = 365 nm), and pyridine (green, l ex = 365 nm).Figure 4. Plots of the emissionpeak against donor number in severals olvents;non-coordinating solvents (blue), oxygen-coordinatings olvents (purple), nitrogen-coordinating solvents (green), chloroform (1), acetonitrile (2), 2,6-dimethylpyridine (3), 2,4,6-trimethylpyridine (4).

Highly Emissive Cerium(III) Thiocyanate Complexes Reevaluated Using a Silane‐Treated Quartz Cell

“…The apparent emission quantum yield decreases up to 1 equivalent of SCN À and then significantly increases up to 4 SCN À equivalents, the value of which reaches a maximum of 88 %, which is higher by a factor of 2 compared with that reported previously (40 %). [11] The apparent emission quantum yield slightly decreases at more than 7 SCN À equivalents, indicating that [Ce(SCN) 4 ] À has a smaller quantum yield. The least-squares nonlinear curve fitting based on equation (10) in the Experimental Section was performed (Figure 6, blue curve) to estimate the actual emission quantum yields of each Ce(III) species, giving Φ 0 = 68 %, Φ 1 = 2.6 %, Φ 2 = 70 %, Φ 3 = 91 %, and Φ 4 = 59 % for Ce 3 + , [Ce(SCN)] 2 + , [Ce(SCN) 2 ] + , Ce(SCN) 3 , and [Ce(SCN) 4 ] À , respectively.…”

“…As described above, in our previous report, the UV-vis absorption spectra during titration of n Bu 4 NSCN to Ce(OTf) 3 in acetonitrile showed featureless broad absorption bands reaching 500 nm accompanied by the 4f-5d transition band. [11] We again carried out the titration of SCN À to Ce(III) ion by using a silane-treated quartz cell. The comparison of the UV-vis absorption spectra with and without the silane treatment on the quartz cell is shown in Figure 2.…”

“…The orders of the values were consistent with values reported previously. [11,19] Extraction of the contributions of each Ce(III) species. The distribution of the Ce(III) species estimated from the above association constants is shown in Figure 4.…”

“…[10] In 2019, we reported that the Ce(III) thiocyanate complex showed solvoluminescence, in which the solvents with low coordinating abilities such as acetonitrile and toluene gave blue emission and oxygen-and nitrogen-coordinating solvents afforded near-UV and green emissions, respectively. [11] Among the solvents, acetonitrile has high solubility for the Ce(III) thiocyanate complex and gave high emission intensity. Experiments of SCN À titration indicated that the Ce(III) thiocyanate complex with three SCN À ligands was the most emissive, in which the maximum apparent emission quantum yield was estimated to be > 40 % with the relative method using emission intensities by taking the absorbance into account.…”

“…Experiments of SCN À titration indicated that the Ce(III) thiocyanate complex with three SCN À ligands was the most emissive, in which the maximum apparent emission quantum yield was estimated to be > 40 % with the relative method using emission intensities by taking the absorbance into account. [11] Considering that the Ce(III) ion can accept up to seven SCN À ligands, [7] an emissive Ce(III) complex such as Ce(SCN) 3 is coordinatively unsaturated. In addition, the SCN À ligands of the Ce(III) thiocyanate complexes exchange rapidly.…”