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## Creator

Takuma Nakai, Kaori Shima, Mengfei Wang, [Sunao Shoji](https://orcid.org/0000-0002-0329-1136), [Takayuki Nakanishi](https://orcid.org/0000-0003-3412-2842), Koji Fushimi, Yasuchika Hasegawa, [Yuichi Kitagawa](https://orcid.org/0000-0003-1487-2531)

## Rights

This is the peer reviewed version of the following article: T. Nakai, K. Shima, M. Wang, S. Shoji, T. Nakanishi, K. Fushimi, Y. Hasegawa, Y. Kitagawa, Angew. Chem. Int. Ed.. 2025, 64, e202513236, which has been published in final form at https://doi.org/10.1002/anie.202513236. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.[In Copyright](http://rightsstatements.org/vocab/InC/1.0/)

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[Dynamic Molecular Triplet Excitons Tune Lanthanide Emission Lifetime](https://mdr.nims.go.jp/datasets/8fa8d5f4-d3ee-4be6-b7df-81b35610f903)

## Fulltext

1  Supporting Information   Dynamic Molecular Triplet Excitons Tune Lanthanide Emission Lifetime  Takuma Nakai,[a] Kaori Shima,[a] Mengfei Wang,[b,c] Sunao Shoji,[d] Takayuki Nakanishi,[e] Koji Fushimi,[b] Yasuchika Hasegawa,[b,c] Yuichi Kitagawa[b,c]*  [a] Graduate School of Chemical Sciences and Engineering, Hokkaido University, Kita 13, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan. [b] Faculty of Engineering, Hokkaido University, Kita 13, Nishi 8, Kita-ku, Sapporo, Hokkaido 060–8628, Japan. [c] Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Kita 21, Nishi 10, Kita-ku, Sapporo, Hokkaido 001-0021, Japan. [d] Faculty of Engineering, Nara Women’s University, Kitauoya-Nishimachi, Nara 630-8506, Japan. [e] National Institute for Material Science, Namiki, Tsukuba, Ibaraki 305-0044, Japan.  E-mail: y-kitagawa@eng.hokudai.ac.jp  2  1 Methods 1.1 Materials Lutetium chloride hexahydrate (99.99%) was purchased from Aldrich Co., Ltd. Europium nitrate hexahydrate (99.95%), terbium chloride hexahydrate (99.95%), n-butyllithium in n-hexane (1.6 mol/L), and chloroform-d (99.8%) were obtained from Kanto Chemical Co., Inc. Tetrahydrofuran, super dehydrated, stabilizer free (for organic synthesis), hydrogen peroxide (30%), anhydrous sodium sulfate, methanol-d4, and chloroform (for spectrochemical analysis) were obtained from Wako Pure Chemical Industries, Ltd. Chlorodiphenylphosphine (>97.0%), chlorodicyclohexylphosphine (>97.0%), 2,2,6,6-tetramethyl-3,5-heptanedione (>97.0%), and 2,7-dibromophenanthrene (>98.0%) were purchased from Tokyo Chemical Industry Co., Ltd.  1.2 General methods 1H-NMR, 13C-NMR, and 31P-NMR spectra were recorded in chloroform-d or methanol-d4 using a JEOL ECS-400 spectrometer (1H: 400 MHz, 13C: 100 MHz, 31P: 162 MHz). Tetramethylsilane (TMS, δH = 0 ppm for 1H-NMR, δC = 0 ppm for 13C-NMR) and H3PO4 (δP = 0 ppm for 31P-NMR) were used as internal standards. Elemental analyses were performed using MICRO CORDER JM10. Electrospray ionization (ESI) mass spectrometry was conducted on a JEOL JMS-T100 LP instrument. Absorption spectra of dpph and dcph were measured using a JASCO V-670 spectrometer. Fourier transform infrared (FT-IR) spectra were measured using a JASCO FT/IR-4600 instrument. Diffuse-reflectance spectra of Lu2-dpph and Eu2-dpph, diluted 100-fold in KBr, were recorded using a JASCO V-670 spectrometer equipped with an integrating sphere (JASCO ISN-723). Emission spectra (λex = 356 nm), excitation spectra (λem = 548 and 612 nm, diluted 10,000-fold in KBr), and emission decay curves (λex = 356 nm, λem = 548, 608, and 612 nm) were obtained using a Horiba FluoroLog®3 spectrofluorometer. Emission quantum yields (λex = 356 nm) of the mixed lanthanide crystals were measured using FP-6300 spectrofluorometer with an integration sphere (ILF-533). Powder X-ray diffraction (PXRD) was performed on a Rigaku SmartLab using MoKα radiation (λ = 0.71073 Å). The ratios of Eu3+ (or Tb3+) in the mixed lanthanide crystals were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES, Agilent 5900). Emission photographs were taken using a PENTAX K-70. 3  1.3 Preparation of 2,7-bis(diphenylphosphoryl)phenanthrene (dpph) The dpph ligand was synthesized by the same method in the previous report.[25]   Yield: 38.2%, 0.198 g, 3.42 mmol. 1H NMR (400 MHz, chloroform-d, Figure S1) δ/ppm = 8.75 (dd, J = 8.8 Hz, 2.4 Hz, 2H), 8.31 (dd, J = 13.4 Hz, 1.0 Hz, 2H), 7.88 (t, J = 9 Hz, 2H), 7.79-7.47 (m, 22H). 31P-NMR (162 MHz, chloroform-d, Figure S2) δ/ppm = 28.8 (s). ESI-MS: m/z calcd. for [C38H29O2P2]+ = 579.16; found: 579.16.   1.4 Preparation of 2,7-bis(dicyclohexylphosphoryl)phenanthrene (dcph) n-Butyllithium (4.9 mL, 7.9 mmol) was added dropwise to a solution of 2,7-dibromophenanthrene (1.20 g, 3.58 mmol) in dry tetrahydrofuran (20 mL) at −80 ℃ under Ar atmosphere. After 0.5 h, chlorodicyclohexylphosphine (1.8 mL, 8.2 mmol) was added to the solution and stirred for 1.0 h at −80 ℃ under Ar atmosphere and then stirred for 2.5 h at room temperature. A 30% hydrogen peroxide aqueous solution (5 mL) was added to the solution and stirred for 2 h at 0 ℃. The product was extracted by dichloromethane and distilled water, and then the organic layer was dried over anhydrous Na2SO4. The crude product was purified by silica gel column chromatography (ethyl acetate:methanol = 9:1).  Yield: 70.6%, 1.52 g, 2.52 mmol. 1H NMR (400 MHz, methanol-d4, Figure S3) δ/ppm = 8.99 (dd, J = 8.7 Hz, 2.3 Hz, 2H), 8.36 (d, J = 11.0 Hz, 2H), 8.00 (s, 2H), 7.95 (td, J = 8.5 Hz, 1.2 Hz, 2H), 2.42-2.24 (m, 4H), 2.16-2.02 (m, 4H), 1.90-1.61 (m, 16H), 1.49-1.18 (m, 16H), 1.18-1.04 (m, 4H). 31P-NMR (162 MHz, chloroform-d, Figure S4) δ/ppm = 45.3 (s). ESI-MS: m/z calcd. for [C38H53O2P2]+ = 603.35; found: 603.35.   1.5 Preparation of [Lu(tmh)3] Lutetium chloride hexahydrate (2.01 g, 5.16 mmol) was dissolved in water (4 mL) and ethanol (2 mL). 2,2,6,6-Tetramethyl-3,5-heptanedione (tmh; 2.85 g, 15.5 mmol) was added dropwise to the solution, and then an ammonia solution was added dropwise until pH reached 9. After stirring for 1.5 h, water (200 mL) was added to the solution. After stirring for 18 h, the resulting white precipitate was collected by filtration. The obtained 4  powder was dried by heating at 373 K.  Yield: 76.2%, 2.85 g, 3.93 mmol. Elemental analysis calcd. (%) for C33H57LuO6, C 54.69, H 7.93; found: C 54.45, H 7.90; ESI-MS: m/z calcd. for [C33H58LuO6]+ = 725.36; found: 725.36.  1.6 Preparation of [Ln2(tmh)6] (Ln3+ = Eu3+ or Tb3+) Europium nitrate hexahydrate (1.01 g, 2.26 mmol) or terbium chloride hexahydrate (1.01 g, 2.70 mmol) was dissolved in water (4 mL) and ethanol (2 mL). 2,2,6,6-Tetramethyl-3,5-heptanedione (tmh; 1.24 g, 6.71 mmol for [Eu2(tmh)6] or 1.51 g, 8.21 mmol for [Tb2(tmh)6]) was added dropwise to the solution, and then an ammonia solution was added dropwise until pH reached 9. After stirring for 1.5 h, water (250 mL for [Eu2(tmh)6] or 200 mL for [Tb2(tmh)6]) was added to the solution. After stirring for 19 h (for [Eu2(tmh)6]) or 8 h (for [Tb2(tmh)6]), the reaction solution was filtered to obtain white powder. The white powder was recrystallized in methanol.  [Eu2(tmh)6] Yield: 27.4%, 0.870 g, 0.620 mmol. Elemental analysis calcd. (%) for C66H114Eu2O12, C 56.48, H 8.19; found: C 56.28, H 8.19; ESI-MS: m/z calcd. for [C55H95Eu2O10]+ = 1219.53; found: 1219.54. [Tb2(tmh)6] Yield: 40.1%, 1.53 g, 1.08 mmol. Elemental analysis calcd. (%) for C66H114O12Tb2, C 55.93, H 8.11; found: C 55.73, H 8.10; ESI-MS: m/z calcd. for [C66H114NaO12Tb2]+ = 1439.67; found: 1439.55.  1.7 Preparation of [Lu2(tmh)6dpph] (Lu2-dpph) [Lu2(tmh)6dpph] was prepared by the same procedure in the previous report.[25]  Elemental analysis calcd. (%) for C104H142Lu2O14P2, C 61.59, H 7.06; found: C 61.19, H 7.06; ESI-MS: m/z calcd. for [C82H104Lu2O10P2]2+ = 830.29; found: 830.28.  5  1.8 Preparation of [Eu2(tmh)6dpph] (Eu2-dpph) The dpph ligand (50.5 mg, 0.09 mmol) and [Eu2(tmh)6] (121.3 mg, 0.086 mmol) were dissolved in methanol (7 mL). The solution was refluxed for 2 h. The mixture was filtered and then recrystallized in methanol at 25 ℃ (Yield: 30.5%, 52.8 mg, 0.027 mmol). Elemental analysis calcd. (%) for C104H142Eu2O14P2, C 63.02, H 7.22; found: C 62.82, H 7.18; ESI-MS: m/z calcd. for [C82H104Eu2O10P2]2+ = 807.27; found: 807.29.  1.9 Preparation of [Tb2(tmh)6dpph] (Tb2-dpph) [Tb2(tmh)6dpph] was prepared by the same procedure in the previous report.[25]  Elemental analysis calcd. (%) for C104H142O14P2Tb2, C 62.58, H 7.17; found: C 62.25, H 7.14; ESI-MS: m/z calcd. for [C82H104O10P2Tb2]2+ = 814.28; found: 814.29.  1.10 Preparation of [EuxLu2-x(tmh)6dpph] (EuxLu2-x-dpph, x = 0.010, 0.028, or 0.084) [Eu0.010Lu1.990(tmh)6dpph]: The dpph ligand (50.8 mg, 8.78 × 10-2 mmol), [Lu(tmh)3] (123.31 mg, 0.16875 mmol), and [Eu2(tmh)6] (1.20 mg, 8.55 × 10-4 mmol) were dissolved in methanol (7 mL). The solution was refluxed for 4 h at 70 ℃. The mixture was filtered and then recrystallized in methanol at 25 ℃ (Yield: 54.1%, 96.3 mg, 4.75 × 10-2 mmol). The chemical compositions of Lu3+ and Eu3+ were determined by ICP-AES (Eu3+/(Eu3++Lu3+) = 0.51%). Elemental analysis calcd. (%) for C104H142Eu0.010Lu1.990O14P2, C 61.60, H 7.06; found: C 61.48, H 7.04.  [Eu0.028Lu1.972(tmh)6dpph]: The dpph ligand (50.4 mg, 8.71 × 10-2 mmol), [Lu(tmh)3] (118.17 mg, 0.16304 mmol), and [Eu2(tmh)6] (6.02 mg, 4.29 × 10-3 mmol) were dissolved in methanol (7 mL). The solution was refluxed for 3.5 h at 70 ℃. The mixture was filtered and then recrystallized in methanol at 25 ℃ (Yield: 55.6%, 98.1 mg, 4.84 × 10-2 mmol). The chemical compositions of Lu3+ and Eu3+ were determined by ICP-AES (Eu3+/(Eu3++Lu3+) = 1.4%). 6  Elemental analysis calcd. (%) for C104H142Eu0.028Lu1.972O14P2, C 61.61, H 7.06; found: C 61.72, H 7.05.  [Eu0.084Lu1.916(tmh)6dpph]: The dpph ligand (50.4 mg, 8.71 × 10-2 mmol), [Lu(tmh)3] (112.77 mg, 0.15559 mmol), and [Eu2(tmh)6] (12.19 mg, 8.69 × 10-3 mmol) were dissolved in methanol (7 mL). The solution was refluxed for 3 h at 70 ℃. The mixture was filtered and then recrystallized in methanol at 25 ℃ (Yield: 47.3%, 83.4 mg, 4.12 × 10-2 mmol). The chemical compositions of Lu3+ and Eu3+ were determined by ICP-AES (Eu3+/(Eu3++Lu3+) = 4.2%). Elemental analysis calcd. (%) for C104H142Eu0.084Lu1.916O14P2, C 61.65, H 7.06; found: C 61.71, H 7.05.  1.11 Preparation of [TbxLu2-x(tmh)6dpph] (TbxLu2-x-dpph, x = 0.013, 0.060, or 0.14) [Tb0.013Lu1.987(tmh)6dpph]: The dpph ligand (50.9 mg, 8.80 × 10-2 mmol), [Lu(tmh)3] (124.01 mg, 0.17110 mmol), and [Tb2(tmh)6] (1.23 mg, 8.68 × 10-4 mmol) were dissolved in methanol (7 mL). The solution was refluxed for 3 h at 70 ℃. The mixture was filtered and then recrystallized in methanol at 25 ℃ (Yield: 47.0%, 83.8 mg, 4.13 × 10-2 mmol). The chemical compositions of Lu3+ and Tb3+ were determined by ICP-AES (Tb3+/(Tb3++Lu3+) = 0.66%). Elemental analysis calcd. (%) for C104H142Lu1.987O14P2Tb0.013, C 61.60, H 7.06; found: C 61.53, H 7.03.  [Tb0.060Lu1.940(tmh)6dpph]: The dpph ligand (50.6 mg, 8.75 × 10-2 mmol), [Lu(tmh)3] (119.00 mg, 0.16419 mmol), and [Tb2(tmh)6] (6.02 mg, 4.31 × 10-3 mmol) were dissolved in methanol (7 mL). The solution was refluxed for 2.5 h at 70 ℃. The mixture was filtered and then recrystallized in methanol at 25 ℃ (Yield: 54.4%, 96.5 mg, 4.76 × 10-2 mmol). The chemical compositions of Lu3+ and Tb3+ were determined by ICP-AES (Tb3+/(Tb3++Lu3+) = 3.0%). Elemental analysis calcd. (%) for C104H142Lu1.940O14P2Tb0.060, C 61.62, H 7.06; found: C 61.73, H 7.06.  [Tb0.140Lu1.860(tmh)6dpph]: The dpph ligand (50.0 mg, 8.64 × 10-2 mmol), [Lu(tmh)3] (112.72 mg, 0.15552 mmol), and [Tb2(tmh)6] (12.19 mg, 8.64 × 10-3 mmol) were dissolved in methanol (7 mL). The solution was 7  refluxed for 2.5 h at 70 ℃. The mixture was filtered and then recrystallized in methanol at 25 ℃ (Yield: 51.9%, 90.8 mg, 4.48 × 10-2 mmol). The chemical compositions of Lu3+ and Tb3+ were determined by ICP-AES (Tb3+/(Tb3++Lu3+) = 6.9%). Elemental analysis calcd. (%) for C104H142Lu1.860O14P2Tb0.140, C 61.69, H 7.07; found: C 61.81, H 7.06.  1.12 Preparation of [Eu2(tmh)6dcph] (Eu2-dcph) The dcph ligand (30.9 mg, 5.13 × 10-2 mmol) and [Eu2(tmh)6] (70.9 mg, 5.05 × 10-2 mmol) were dissolved in methanol (5 mL). The solution was refluxed for 2 h at 70 ℃. The mixture was filtered and then recrystallized in methanol at 25 ℃ (Yield: 33.5%, 34.5 mg, 1.72 × 10-2 mmol).  Elemental analysis calcd. (%) for C104H166Eu2O14P2, C 62.26, H 8.34; found: C 61.29, H 8.31; ESI-MS: m/z calcd. for [C82H128Eu2O10P2]2+ = 819.37; found: 819.43.  1.13 Preparation of [Tb2(tmh)6dcph] (Tb2-dcph) The dcph ligand (30.0 mg, 4.98 × 10-2 mmol) and [Tb2(tmh)6] (71.1 mg, 5.02 × 10-2 mmol) were dissolved in methanol (5 mL). The solution was refluxed for 2 h at 70 ℃. The mixture was filtered and then recrystallized in methanol at 25 ℃ (Yield: 30.5%, 30.8 mg, 1.52 × 10-2 mmol).  Elemental analysis calcd. (%) for C104H166Tb2O14P2, C 61.83, H 8.28; found: C 60.95, H 8.28; ESI-MS: m/z calcd. for [C82H128O10P2Tb2]2+ = 826.37; found: 826.37.  1.14 Preparation of [Lu2(tmh)6dcph] (Lu2-dcph) The dcph ligand (50.5 mg, 8.38 × 10-2 mmol) and [Lu(tmh)3] (120 mg, 1.66 × 10-1 mmol) were dissolved in methanol (7 mL). The solution was refluxed for 5 h at 70 ℃. The mixture was filtered and then recrystallized in methanol at 25 ℃ (Yield: 29.4%, 85.9 mg, 4.19 × 10-2 mmol).  Elemental analysis calcd. (%) for C104H166Lu2O14P2, C 60.86, H 8.15; found: C 60.64, H 8.20; ESI-MS: m/z calcd. for [C104H167Lu2O14P2]+ = 2053.07; found: 2053.11.  8  1.15 Preparation of [Eu0.005Lu1.995(tmh)6dcph] (Eu0.005Lu1.995-dcph) The dcph ligand (50.8 mg, 8.43 × 10-2 mmol), [Lu(tmh)3] (119.3 mg, 0.16460 mmol), and [Eu2(tmh)6] (1.18 mg, 8.41 × 10-4 mmol) were dissolved in methanol (7 mL). The solution was refluxed for 10.5 h at 70 ℃. The mixture was filtered and then recrystallized in methanol at 25 ℃ (Yield: 41.5%, 71.0 mg, 3.50 × 10-2 mmol). The chemical compositions of Lu3+ and Eu3+ were determined by ICP-AES (Eu3+/(Eu3++Lu3+) = 0.26%). Elemental analysis calcd. (%) for C104H166Eu0.005Lu1.995O14P2, C 60.87, H 8.15; found: C 60.69, H 8.18.  1.16 Preparation of [Tb0.011Lu1.989(tmh)6dcph] (Tb0.011Lu1.989-dcph) The dcph ligand (50.9 mg, 8.44 × 10-2 mmol), [Lu(tmh)3] (119.1 mg, 0.16433 mmol), and [Tb2(tmh)6] (1.17 mg, 8.25 × 10-4 mmol) were dissolved in methanol (7 mL). The solution was refluxed for 5 h at 70 ℃. The mixture was filtered and then recrystallized in methanol at 25 ℃ (Yield: 41.5%, 73.0 mg, 3.50 × 10-2 mmol). The chemical compositions of Lu3+ and Tb3+ were determined by ICP-AES (Tb3+/(Tb3++Lu3+) = 0.54%). Elemental analysis calcd. (%) for C104H166Lu1.989O14P2Tb0.011, C 60.87, H 8.15; found: C 60.71, H 8.18.  1.17 Single-crystal X-ray determination Single crystals of [Ln2(tmh)6dpph] (Ln3+ = Eu3+, Tb3+, and Lu3+) were obtained by recrystallization from methanol. Single-crystal X-ray structural analyses were carried out using a Rigaku XtaLAB Synergy-R/DW equipped with a Hypix-6000HE detector (MoKα radiation, λ = 0.71703 Å). The structure was solved using direct methods and expanded using Fourier techniques. Non-hydrogen atoms were refined anisotropically using the SHELX system.[41] Hydrogen atoms were refined using the riding model. All calculations were performed using the Olex2 crystallographic software package except for the refinement, which was performed using SHELXL.[42] The CIF data were confirmed by the checkCIF/PLATON service. CCDC-2426790 (for [Eu2(tmh)6dpph]), CCDC-2128735 (for [Tb2(tmh)6dpph]), CCDC-2128731 (for [Lu2(tmh)6dpph]), CCDC-2426793 (for [Lu2(tmh)6dcph]), and CCDC-2478483 (for [Gd2(tmh)6dpph]). The crystallographic data are summarized in Table S1.  9  1.18 Calculation method of photophysical parameters of Eu complex[43] The photophysical parameters, radiative rate constant (kr), non-radiative rate constant (knr), and intrinsic emission quantum yield (Φff) were estimated using the following equations. 𝑘𝑟 =1𝜏rad= 𝐴MD,0𝑛3𝐼tot𝐼MD(S1) 𝜙ff =𝑘𝑟𝑘𝑟 + 𝑘𝑛𝑟=𝜏obs𝜏rad(S2) 𝑘𝑛𝑟 =1𝜏obs−1𝜏rad(S3) where τobs, τrad, AMD,0, n, and Itot/IMD are the observed and radiative emission lifetimes, spontaneous emission probability for 5D0→7F1 transition in degassed condition (14.65 s-1), refractive index of the medium (n = 1.5), and ratio of the total area of 5D0→7FJ (J = 0, 1, 2, 3, 4) bands of Eu(III) emission spectrum to the area of the 5D0→7F1 band, respectively.[43]   10  1.19 NMR spectra of dpph and dcph  Figure S1. 1H-NMR spectrum of dpph in chloroform-d.  Figure S2. 31P-NMR spectrum of dpph in chloroform-d.  abundance01.02.03.04.05.06.07.08.0X : parts per Million : Proton9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 08.7698.7628.7478.7408.3388.3107.8007.7577.7397.7367.7277.7097.7057.5097.4987.4937.4907.2640.0008.098.054.052.001.991.981.96abundance00.10.20.30.40.50.60.70.80.91.01.1X : parts per Million : Phosphorus3130.0 20.0 10.0 0 -10.028.8040.00011   Figure S3. 1H-NMR spectrum of dcph in methanol-d4.  Figure S4. 31P-NMR spectrum of dcph in chloroform-d.   abundance01.02.03.04.05.06.0X : parts per Million : Proton9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 09.0419.0359.0199.0148.4098.3818.0338.0048.0027.9837.9627.9594.9053.3172.4082.3842.3552.3322.1442.1131.8781.8481.7801.7321.7001.4211.4061.3891.3581.3361.3041.2781.1621.1310.90422.0716.004.064.014.002.032.01abundance01.02.03.0X : parts per Million : Phosphorus3160.0 50.0 40.0 30.0 20.0 10.0 0 -10.045.2690.00012  1.20 Infrared spectra of lanthanide complexes  Figure S5. FT-IR spectrum of Lu2-dpph.    Figure S6. FT-IR spectra of Eu2-dpph (red line) and Tb2-dpph (green line).    13     Figure S7. FT-IR spectra of Eu0.010Lu1.990-dpph (orange line), Eu0.028Lu1.972-dpph (pink line), Eu0.084Lu1.916-dpph (red line).    Figure S8. FT-IR spectra of Tb0.013Lu1.987-dpph (blue line), Tb0.060Lu1.940-dpph (yellow line), and Tb0.140Lu1.860-dpph (green line).   14     Figure S9. FT-IR spectrum of Lu2-dcph.    Figure S10. FT-IR spectra of Eu2-dcph (red line), Eu0.005Lu1.995-dcph (orange line), Tb2-dcph (green line), and Tb0.011Lu1.989-dcph (blue line).     15  2 Crystal structure analysis and photophysical properties Supplementary Note 1: Comparison of other non-luminescent lanthanide ions In the present mixed lanthanide system, La3+ and Gd3+ ions are also potential candidates owing to their high lowest excited state levels. To consider the optimal lanthanide ions, we attempted to synthesize the [La2(tmh)6dpph] and [Gd2(tmh)6dpph] complexes using the same scheme as that for [Lu2(tmh)6dpph]. Single crystals of the Gd3+ complex were obtained by recrystallization in a methanol solution. By contrast, the La3+ complex did not crystallize under the identical conditions as those used the Lu3+ and Gd3+ complexes. Single-crystal X-ray diffraction analysis revealed that the Gd3+ complex formed a dinuclear structure (Figure S11, crystallographic data are listed in Table S1), which is similar structure to that of [Lu2(tmh)6dpph]. An emission band was observed at approximately 550 nm in the emission spectrum of [Gd2(tmh)6dpph] (Figure S12), which is assigned to phosphorescence from the dpph ligand. The emission decay curve of [Gd2(tmh)6dpph] was fitted with a triple-exponential function (Figure S13). The average emission lifetime of [Gd2(tmh)6dpph] was estimated as 36.3 ms (τ1 = 26.3 ms (79.9%), τ2 = 67.0 ms (20.0%), τ3 = 1340 ms (0.01%)), which is shorter than that of [Lu2(tmh)6dpph] (47 ms). Based on these results, [Lu2(tmh)6dpph] was selected as the host crystal for effective delayed emission from Eu3+ and Tb3+.  Figure S11. ORTEP drawings of [Gd2(tmh)6dpph] (50% probability ellipsoids). Gray spheres represent carbon; red spheres, oxygen; orange spheres, phosphorus; light green spheres, gadolinium. Hydrogen atoms are omitted for clarity.  16    Figure S12. Emission spectrum of [Gd2(tmh)6dpph] (ex = 405 nm, 30 ms delay, 100 K, degassed condition).  Figure S13. Emission decay curve of [Gd2(tmh)6dpph] under degassed condition (ex = 380 nm,  em = 530 nm, delay time: 80 ms, 293 K).   17   Table S1. Crystallographic parameters for [Ln2(tmh)6dpph] (Ln3+ = Eu3+, Tb3+, Gd3+ and Lu3+).  [Eu2(tmh)6dpph] [Gd2(tmh)6dpph] [Tb2(tmh)6dpph][25] [Lu2(tmh)6dpph] Chemical formula C104H142Eu2O14P2 C104H142Gd2O14P2 C104H142O14P2Tb2 C104H142O14P2Lu2 Crystal system Triclinic Triclinic Triclinic Triclinic Space group P-1 P-1 P-1 P-1 a / Å 20.4908(3) 20.5881(4) 20.6292(3) 20.6743(3) b / Å 21.7700(3) 21.7908(5) 21.8080(3) 21.7193(3) c / Å 23.8309(3) 23.8658(5) 23.8231(3) 23.5751(3) Volume / Å3 10514.5(3) 10594.2(4) 10599.8(3) 10467.7(3) Z 4 4 4 4 Density / g cm-3 1.252 1.249 1.251 1.287 Temperature / ℃ −150 −150 −150 −150 R 0.0735 0.0840 0.0609 0.0814 wR2 0.2123 0.2090 0.1696 0.2171    18     Figure S14. X-ray crystal structure of Lu2-dpph viewed along the a) c-axis and b) b-axis (50% probability ellipsoids). Except for phenanthrene units, all other atoms are omitted for clarity. The unbonded carbon atoms denote a two-site disorder of the phenanthrene units. Blue spheres represent centroid of 14 carbon atoms.         19   Figure S15. ORTEP drawings of a) Eu2-dpph and b) Tb2-dpph[25] (50% probability ellipsoids). Gray spheres represent carbon; red spheres, oxygen; orange spheres, phosphorus; light green spheres, europium or terbium. Hydrogen atoms are omitted for clarity.   Figure S16. Excitation spectra of Eu2-dpph (red line, em = 612 nm) and Tb2-dpph (green line, em = 548 nm) under degassed condition at 293 K.  20  Supplementary Note 2: Excited state dynamics of Eu2-dpph and Tb2-dpph The photophysical properties of Eu2-dpph and Tb2-dpph are summarized in Table S2. For Eu2-dpph, intrinsic emission quantum yield (Φff) and emission quantum yield by ligand excitation (Φtot) of Eu2-dpph were estimated to be 55.5 and 9.8%, respectively. The calculated photosensitized energy transfer efficiency (ηsens = 17.8%) is inefficient, indicating the presence of quenching state in photosensitization process. To reveal the quenching state, diffuse-reflectance spectra of Eu2-dpph and Lu2-dpph were measured (Figure S17). Absorption bands were observed at 364 and 346 nm, which are assigned to 0-0 and 0-1 π-π* transitions of dpph ligand, respectively. For Eu2-dpph, an additional absorption band arising from 400 nm is also observed. Eu3+ has a lower reduction potential compared to Lu3+ (Eu3+/Eu2+ = −0.35 V vs NHE; Lu3+/Lu2+ = −2.7 V vs NHE[44]), resulting in a ligand-to-metal charge transfer (LMCT) states with lower energy than dpph singlet state. Thus, ineffective energy transfer efficiency in Eu2-dpph is attributed to energy transfer quenching from dpph singlet state.[37-40] Table S2 Photophysical properties of Eu2-dpph and Tb2-dpph.  Φtot[a] / % Φff[b] / % ηsens/ % τ[c] / ms Eu2-dpph 9.8 55.5 17.8 0.55 Tb2-dpph 67.9 --- --- 0.83 [a] λex = 375 nm, crystalline state, N2 atmosphere, 293 K. [b] Φff was calculated from equation S1-S3[43]. [c] λex = 356 nm, λem = 612 nm (for Eu2-dpph) or 548 nm (for Tb2-dpph), 293 K.  Figure S17. Diffuse-reflectance spectra of Eu2-dpph (red) and Lu2-dpph (black).  21   Figure S18. Emission decay curves of Eu2-dpph (red line, ex = 510 nm, em = 612 nm, crystalline state) and Tb2-dpph (green line, ex = 495 nm, em = 548 nm, crystalline state) by direct Eu3+ or Tb3+ excitation at 293 K under degassed condition.   Figure S19. Energy diagrams of Eu2-dpph (upper) and Tb2-dpph (lower). Emission lifetimes of Eu2-dpph and Tb2-dpph by dpph excitation were almost consistent with those by Eu3+ or Tb3+ excitation. This result indicates the inexistence of intermolecular energy transfer.  22   Figure S20. Powder X-ray diffraction patterns of Lu2-dpph (black line), Eu0.084Lu1.916-dpph (red line), Eu0.028Lu1.972-dpph (pink line), Eu0.010Lu1.990-dpph (orange line), Tb0.140Lu1.860-dpph (green line), Tb0.060Lu1.940-dpph (yellow line), and Tb0.013Lu1.987-dpph (blue line).   23   Figure S21. Emission spectra (λex = 356 nm, crystalline state, 293 K, under degassed condition) of Eu0.084Lu1.916-dpph (red line), Eu0.028Lu1.972-dpph (pink line), Eu0.010Lu1.990-dpph (orange line), Tb0.140Lu1.860-dpph (green line), Tb0.060Lu1.940-dpph (yellow line), and Tb0.013Lu1.987-dpph (blue line).   24    Figure S22. Emission decay curves (λex = 356 nm, crystalline state, 293 K, under degassed condition) of Eu0.084Lu1.916-dpph (λem = 612 nm, red line), Eu0.028Lu1.972-dpph (λem = 612 nm, pink line), Eu0.010Lu1.990-dpph (λem = 612 nm, orange line), Tb0.140Lu1.860-dpph (λem = 548 nm, green line), Tb0.060Lu1.940-dpph (λem = 548 nm, yellow line), and Tb0.013Lu1.987-dpph (λem = 548 nm, blue line).    25   Table S3 Fitting results for emission decay curves of mixed lanthanide crystals.  τavg / ms τ1 / ms τ2 / ms τ3 / ms Eu2-dpph 0.55 --- --- --- Eu0.084Lu1.916-dpph 1.22 0.99 (81.2%) 2.14 (18.8%) 25.5 (0.7%) Eu0.028Lu1.972-dpph 3.54 1.88 (47.4%) 4.80 (51.6%) 16.8 (1.0%) Eu0.010Lu1.990-dpph 7.42 2.56 (33.8%) 8.02 (52.8%) 17.3 (13.4%) Eu0.005Lu1.995-dcph 148 20.7 (21.9%) 104 (30.8%) 235 (47.2%) Tb2-dpph 0.83 --- --- --- Tb0.140Lu1.860-dpph 1.31 1.27 (99.6%) 6.02 (0.33%) 13.2 (0.04%) Tb0.060Lu1.940-dpph 2.14 1.88 (89.7%) 3.88 (10.2%) 5.77 (0.1%) Tb0.013Lu1.987-dpph 7.80 3.76 (39.1%) 9.78 (59.1%) 30.4 (1.8%) Tb0.011Lu1.989-dcph 152 27.1 (29.4%) 172 (66.3%) 700 (4.3%)    26   Figure S23. Powder X-ray diffraction patterns of Lu2-dcph (black line), Eu0.005Lu1.995-dcph (red line), and Tb0.011Lu1.989-dpph (green line).    Figure S24. Emission spectra (λex = 356 nm, crystalline state, 293 K, under degassed condition) of Eu0.005Lu1.995-dcph (red line) and Tb0.011Lu1.989-dcph (green line).  27   Figure S25. Emission decay curves (λex = 356 nm, crystalline state, 293 K, under degassed condition) of Eu0.005Lu1.995-dcph (λem = 608 nm, red line) and Tb0.011Lu1.989-dcph (λem = 548 nm, green line).   28  Supplementary Note 3: Evaluation of emission lifetime for Lu2-dcph To evaluate the emission lifetime for [Lu2(tmh)6dcph] (where Lu2-dcph), Lu2-dcph was synthesized and single-crystal X-ray diffraction measurement was performed. Lu2-dcph is seven-coordinated dinuclear structure, in which two [Lu(tmh)3] units are connected by dcph ligand (Figure S26, crystallographic parameters are shown in Table S4). One phenanthrene unit in Lu complex is surrounded by two adjacent phenanthrene units at distance of 1.14 nm (Figure S27). The emission spectrum of Lu2-dcph crystal exhibited broad emission bands at around 550 nm (Figure S28), which originated from the - transition of dcph ligand. The T1 level of dcph ligand was estimated to be 20,000 cm-1 based on the emission spectrum deconvolution using Gaussian functions. The emission decay curve of Lu2-dcph (Figure S29) was fitted using triple-exponential functions and the emission lifetime was estimated to be 246 ms (τ1 = 54.3 ms (67.5%), τ2 = 273 ms (17.1%), τ3 = 1057 ms (15.4%)).    29    Figure S26. ORTEP drawing of Lu2-dcph (50% probability ellipsoids). Hydrogen atoms are omitted for clarity. Gray spheres represent carbon; red spheres, oxygen; orange spheres, phosphorus; green spheres, lutetium.  Figure S27. X-ray crystal structure of Lu2-dcph viewed from b-axis (50% probability ellipsoids). The distances were calculated based on the centroids of phenanthrene units.   30    Table S4. Crystallographic parameters for [Lu2(tmh)6dcph]  [Lu2(tmh)6dcph] Chemical formula C104H166O14P2Lu2 Crystal system Monoclinic Space group P21/c a / Å 29.9349(8) b / Å 24.2487(6) c / Å 22.7643(5) Volume /Å3 16498.5(7) Z 6 Density / g cm-3 1.239 Temperature / ℃ −150 R 0.0671 wR2 0.1866    31    Figure S28. Emission spectrum (λex = 400 nm, delay time: 80 ms, crystalline state, 100 K, under degassed condition) of Lu2-dcph.   Figure S29. Emission decay curve (λex = 400 nm, λem = 530 nm, crystalline state, 298 K, under degassed condition) of Lu2-dcph.   32   Figure S30. Spece-fill drawing models of a) Lu2-dpph and b) Lu2-dcph.   Figure S31. Absorption spectra of dpph (solid line, 0.8 mM) and dcph (dashed line, 0.8 mM). Absorption coefficients at 356 nm of dpph and dcph were determined to be 575 and 872 M-1 cm-1, respectively.  33  Supplementary Note 4: Photophysical properties of Eu2-dcph and Tb2-dcph For the evaluation of photophysical properties for Eu0.005Lu1.995-dcph and Tb0.011Lu1.989-dcph, pure lanthanide crystals ([Eu2(tmh)6dcph]: Eu2-dcph and [Tb2(tmh)6dcph]: Tb2-dcph) were synthesized and identified by the same procedure of (Eu2-dpph and Tb2-dpph). Eu2-dpph exhibits emission bands at 578, 594, 608, 655, 701 nm (Figure S32), which are assigned to 5D0 → 7FJ (J = 0, 1, 2, 3, and 4, respectively). For Tb2-dpph, emission bands at 489, 548, 581, 616, and 655 nm were observed (Figure S33), assigned to 5D4 → 7FJ (J = 6, 5, 4, 3, and 2, respectively). The emission spectra shapes of Eu2-dcph and Tb2-dcph are similar to those of Eu0.005Lu1.995-dcph and Tb0.011Lu1.989-dcph, respectively, indicating similar coordination environment between pure lanthanide crystals and mixed lanthanide crystals. The photophysical properties of Eu2-dcph and Tb2-dcph are summarized in Table S5. From the emission decay analyses of Eu2-dcph and Tb2-dcph (Figure S34), the emission lifetimes were estimated to be 0.46 and 0.63 ms, respectively. The emission quantum yields for Eu2-dcph and Tb2-dcph were estimated to be 5.2 and 63%, respectively. The IB values were evaluated to be 45.3 (Eu2-dcph) and 549 (Tb2-dcph) M-1 cm-1. From these results, effective photosensitized emission is considered to occur in Eu0.005Lu1.995-dcph and Tb0.011Lu1.989-dcph.  Table S5 Photophysical properties of Eu2-dcph and Tb2-dcph.  τ[a] / ms Φtot[b] / % IB[c] / M-1 cm-1 Eu2-dcph 0.46 5.2 45.3 Tb2-dcph 0.63 63.0 549 [a] λex = 360 nm, λem = 612 nm (for Eu2-dpph) or 548 nm (for Tb2-dpph). [b] λex = 356 nm, N2 flow. [c] λex = 356 nm.   34   Figure S32. Emission spectra (λex = 356 nm, 298 K, crystalline state, under degassed condition) of Eu2-dcph (upper) and Eu0.005Lu1.995-dcph (lower).   Figure S33. 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