Fig.1 Reported bridging modes of alkyl ligand(A), carboxyl ligand(B) and salicylic acid ligand(C) in LTOCs

Fig.2 Metal nuclearity distribution of LTOCs

Fig.3 Structural views of Sm4Ti(μ5?O)(μ3?OiPr)2(μ?OiPr)6(OiPr)6(A), Ce2Ti2(μ3?O)2(μ,η2?pin)4(OiPr)4(iPrOH)2(B), Er2Ti4(μ4?O)2(μ3?OEt)2(μ?OEt)8(OEt)8(HOEt)2(C), Eu3K3TiO2(OtBu)11(OMe/OH)(HOtBu)(D), LnTi28O38(OEt)40H2Cl(E) and LnTi11O16(NO3)2(OiPr)17(F)Color code: Ln, violet; TiOx, green; K, orange; C, gray; O, red; N, blue; Cl, teal. H atoms are omitted for clarity.

Fig.4 Structural views of Y2Ti4O4(OMc)14(MeOCH2CH2OH)2(A),Y2Ti4O4(OMc)12(OCH2CH2OMe)2(McOH)2(B), Ln2Ti6O6(OMc)18(HOiPr)2(C), LnTi4O3(OiPr)2(OMc)11(D), Ln2Ti10O14(ClO4)2(OiPr)14(9?AC)2·(CH3CN)2(E), {H2@[Ln2Ti8(μ2?O)4(μ3?O)8(Ac)16]}3(F), Eu2Ti4(μ3?O)4(tbba)12(acac)2(G), Eu5Ti4(μ3?O)6·(tbba)20(Htbba)(THF)2(H), Eu3Ti3(μ3?O)2(μ3?OH)(CH3O)2(tbba)12(Ac)2(CH3OH)(I), Eu6Ti8(μ3?O)13· (μ2?OH)?(CH3O)4(tbba)19(H2O)(CH3OH)(J) and Eu8Ti10(μ3?O)14(tbba)34(Ac)2(H2O)4(THF)2(K)Color code: Ln, violet; TiOx, green; C, gray; O, red; N, blue; Cl, teal. H atoms are omitted for clarity.

Fig.5 Structural views of LnTi6O3(OiPr)9(salicylate)6(A) and Eu24Ti8(sal)31(Hsal)42(CH3CN)11(H2O)8(B) and time?dependent HRESI?MS in range of m/z 1750—2800 on the reaction of Ti(OiPr)4, Eu(acac)3, and salicylic acid in acetonitrilesolution at 2, 30, 60, 120, and 240 min at room temperature(C)[73]Color code: Ln, violet; TiOx, green; C, gray; O, red; N, blue. H atoms are omitted for clarity.Copyright 2018, Wiley-VCH.

Fig.6 Photos of the fluorescence emission of Eu2Ti10?bza(a) and Eu2Ti10?9?AC(b)(A) and proposed energy transfer processes in cluster Eu2Ti10?9?AC[48](B)Copyright 2015, Royal Society of Chemistry.

Fig.7 Temperature dependence of the emission intensity of Eu2Ti4 in the range of 100—300 K[51]Copyright 2017, American Chemical Society.

Fig.8 Schematic diagram of the energy transfer from the ligand to Eu3+/Tb3+ in PL emission[53]Copyright 2019, American Chemical Society.

Fig.9 Photoelectrocatalytic amount of O2 of Ln8Ti10(A)[47], structural view of Ln2Ti6O2(C2O4)4(NO3)2·(OiPr)20(B), remaining concentrations using the degradation crystals of Ln2Ti6 ?after 40 min illumination(C)[46] and a proposed cooperative effect of Ln and oxalate promoting the photocatalytic degradation of the dye(D)[46]Color code: Ln, violet; TiOx, green; C, gray; O, red; N, blue. H atoms are omitted for clarity.(A) Copyright 2017, American Chemical Society;(C, D) Copyright 2018, Royal Society of Chemistry.