Bismuth(III) Clusters Assembled with

Publication Date (Web): December 7, 2018 ... With the introduction of bismuth oxido diketonate, [Bi9O7(hfac)13], three different types of rare-earth/b...
18 downloads 0 Views 2MB Size
Download PDF
Article pubs.acs.org/IC

Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX

Hybrid Rare-Earth(III)/Bismuth(III) Clusters Assembled with Phosphonates Jun-Ling Jin, Yun-Peng Xie,* and Xing Lu* State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China

Downloaded via YORK UNIV on December 16, 2018 at 18:31:15 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.

S Supporting Information *

ABSTRACT: tert-Butylphosphonic acid and rare-earth precursors are employed to construct four trinuclear rare-earth phosphonate clusters, RE3(tBuPO3)2(hfac)5(CH3OH)8]·2CH3OH (RE = Eu, Y, Pr, and Sm; hfac = hexafluoroacetylacetonate), which are composed of three RE3+ ions alternately bridged by two phosphonates. With the introduction of bismuth oxido diketonate, [Bi9O7(hfac)13], three different types of rare-earth/bismuth phosphonate clusters, Bi12RE2 (RE = Pr and Sm), Bi6Eu7, and Bi6Y9, are successfully obtained via variation of the reaction conditions, and they are the first reported examples of bismuth−oxo clusters encapsulated by cyclic rareearth−oxo or rare-earth/bismuth−oxo phosphonate clusters, respectively. These clusters show obvious absorption in the UV region, and the Eu-containing clusters exhibit bright-red fluorescence.

■

INTRODUCTION Metal clusters have captured significant attention because of their appealing architectures and potential applications in numerous areas.1 Among a wide range of candidate metals, rare-earth ions are frequently employed in the syntheses of novel clusters because of their luminescent, magnetic, and catalytic properties.2−4 A large variety of rare-earth clusters have been reported in the recent literature with different sizes, compositions, and geometries.5−7 The choice of polydentate ligands with suitable coordination sites plays an important role in the creation of rare-earth clusters. In fact, phosphonates can play a positive role as excellent alternative candidates in the assembly of metallic cluster compounds. Their monoanionic RPO3H− or dianionic RPO32− groups have three oxygen-atom donors that can effectively bridge to various types of metal ions and even to nine metal ions simultaneously and have been used to synthesize various rare-earth phosphonate cluster complexes.8,9 On the other hand, the structural diversity of bismuth clusters has been delineated over the past few decades, and multiple applications such as span materials science, catalysis, and medicine are emerging.10−13 The bismuth(III) and rareearth(III) ions exhibit similar ionic radii, high coordination numbers, and flexible coordination geometry. This should open up the possibility to assemble bismuth and rare-earth atoms within heterometallic clusters with novel electrical or optical properties. Examples of heterobimetallic complexes containing bismuth and rare-earth ions are restricted to carboxylates such as [NdBi(EDTA)(NO3)2] (EDTA = edathamil) and [(BixTb1−x)(O2C2H2)3N].14 Nevertheless, heterobimetallic rare-earth/bismuth phosphonates were not reported so far. © XXXX American Chemical Society

Recently, our group focused on the syntheses of heterometallic clusters constructed with tert-butylphosphonate and successfully isolated several silver/copper and silver/rareearth bimetallic clusters.15 Now, we are interested in extending the family of rare-earth phosphonate clusters to include bismuth clusters, thereby creating a new class of metal−oxo phosphonate clusters that are hybrids of the rare-earth and bismuth families. In this work, we isolated four trinuclear rareearth phosphonate clusters, [RE 3 ( t BuPO 3 ) 2 (hfac) 5 (CH3OH)8]·2CH3OH (1; RE = Eu, Y, Pr, and Sm; hfac = hexafluoroacetylacetonate), and four unprecedented rareearth/bismuth phosphonate clusters: two tetradecanuclear, [Bi12RE2(μ3-O)10(tBuPO3)8(tBuPO3H)4(hfac)2(CH3OH)4]· xCH3OH·2H2O (2; RE = Pr, x = 4; RE = Sm, x = 6), a tridecanuclear, [Bi6Eu7(μ3-O)8(tBuPO3)7(tBuPO3H)3(hfac)6(CH3OH)9(H2O)2]·CH3OH·CH3CN (3), and a pentadecanuclear, {[Bi 6 Y 9 (μ 3 -O) 4 (μ 3 -OH) 4 ( t BuPO 3 ) 1 2 (hfac) 6 (CF3COO)3(CH3OH)9(H2O)6]·6CH3OH·9H2O}·2CH3OH· 17H2O (4). The absorption spectra of complexes 1−4 in methanol or acetonitrile were investigated, and the solution luminescent properties of 1-Eu and 3 were monitored at room temperature.

■

RESULTS AND DISCUSSION Structure of Compound 1. The reaction of RE(hfac)3· 2H2O with tBuPO3H2 in methanol yielded a series of trinuclear rare-earth phosphonate clusters, [RE3( tBuPO3) 2(hfac)5(CH3OH)8]·2CH3OH (1; RE = Eu, Y, Pr, and Sm). A single-crystal X-ray diffraction study showed that type 1 Received: October 3, 2018

A

DOI: 10.1021/acs.inorgchem.8b02811 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry crystallizes in the triclinic space group P1̅ and each owns the same structure. Therefore, only the structure of the complex 1Eu is described in Figure 1. These trinuclear clusters,

Figure 2. Perspective view of Bi12Pr2(μ3-O)10(tBuPO3)8(tBuPO3H)4(hfac)2(CH3OH)4 in 2-Pr with all hydrogen atoms omitted for clarity. The oxygen atoms of the [Bi8O10]4+ core are represented as pink spheres, and the remaining oxygen atoms in 2-Pr are shown as red spheres.

Figure 1. Perspective view of Eu3(tBuPO3)2(hfac)5(CH3OH)8 in 1Eu with all hydrogen atoms omitted for clarity.

[RE3(tBuPO3)2(hfac)5(CH3OH)8], are composed of three rare-earth atoms alternately bridged by two phosphonates, in which three rare-earth atoms are further bound by hfac− ligands and methanol molecules. The RE−O bond lengths decrease as the ionic radii of the RE3+ ions decrease (Pr−O = 2.359−2.591 Å; Sm−O = 2.318−2.526 Å; Eu−O = 2.309− 2.512 Å; Y−O = 2.245−2.464 Å), which is in accordance with the effect of lanthanide contraction.16 In addition, the reaction of the bismuth oxido diketonate, [Bi9O7(hfac)13] with tBuPO3H2, afforded a previously reported tetradecabismuth phosphonate cage, [Bi14O10(tBuPO3)10(tBuPO3H)2].17 It is suggested that RE(hfac)3·2H2O or [Bi9O7(hfac)13] containing labile hfac− ligands can be used as precursors to react with phosphonates, and the hfac− ligands are partly replaced by phosphonate to form newly expanded clusters. The heteronuclear rare-earth/bismuth−oxo clusters might be accessible starting from RE(hfac)3·2H2O and [Bi9O7(hfac)13] as precursors by this methodology. Structure of Compound 2. A solution of RE(hfac)3· 2H2O (RE = Pr and Sm) in methanol was treated with a mixture of t BuPO 3 H 2 and [Bi 9 O 7 (hfac) 13 ], yielding [Bi12RE2(μ3-O)10(tBuPO3)8(tBuPO3H)4(hfac)2(CH3OH)4]· xCH3OH·2H2O (2; RE = Pr, x = 4; RE = Sm, x = 6). Type 2 crystallizes in the triclinic space group P1̅. Complexes 2-Pr and 2-Sm own the same structure, although there is some difference in the solvents on the peripheral. Therefore, only the structure of 2-Pr is described herein. The cluster of 2-Pr can be described as consisting of a cyclic hybrid bismuth−praseodymium phosphonate cluster, [Bi4Pr2(tBuPO3)8(tBuPO3H)4(hfac)2(CH3OH)4]4−, enclosing a bismuth−oxo template, [Bi8O10]4+ (Figures 2 and 3). The cationic [Bi8O10]4+ unit is composed of a central tetranuclear {Bi4O6} unit, which is bound to two {Bi2O2} four-membered rings as poles on either side (Figure 3b). The central {Bi4O6} unit consists of two {Bi2O2} connected through two oxygen atoms that further coordinate to two praseodymium atoms. Additionally, two methanol molecules function as bridging ligands coordinating to two pairs of bismuth centers of the {Bi2O2} four-membered ring. On the other hand, four oxygen atoms from two {Bi2O2} poles are further bound to four

Figure 3. (a) Peripheral anionic hybrid bismuth−praseodymium phosphonate cluster [Bi 4 Pr 2 ( t BuPO 3 ) 8 ( t BuPO 3 H) 4 (hfac) 2 (CH3OH)4]4− in 2-Pr with two hfac− ligands and all methanol molecules omitted. (b) [Bi8O10]4+ core in 2-Pr. The oxygen atoms of the [Bi8O10]4+ core are represented as pink spheres, and the remaining oxygen atoms in 2-Pr are shown as red spheres.

bismuth atoms. All of the Bi−O bond lengths fall in the range of 2.080−2.300 Å. The [Bi8O10]4+ unit is further stabilized through 12 phosphonate ligands from the peripheral anionic cluster [Bi4Pr2(tBuPO3)8(tBuPO3H)4(hfac)2(CH3OH)4]4−. Of the 12 tert-butylphosphonates, four adopt the μ3-bridging mode to coordinate to three bismuth atoms, and the remaining eight use μ4-ligation modes to connect three bismuth atoms with one praseodymium atom. The Bi−OP (OP = oxygen atom of the phosphonate ligand) and Pr−OP bond lengths lie in the ranges of 2.210−2.842 and 2.342−2.510 Å, respectively. Additionally, each of two praseodymium atoms is further coordinated by one hfac− ligand and one methanol molecule. The tetradecanuclear cluster of type 2 can be viewed as a result of two bismuth atoms in the middle of the peripheral anionic hexanuclear bismuth phosphonate cluster in [Bi14O 10(tBuPO3)10(tBuPO3H)2] replaced by two praseodymium atoms, which exhibit a higher ligancy than that of the bismuth atoms. B

DOI: 10.1021/acs.inorgchem.8b02811 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry Structure of Compound 3. Complex 3 was obtained through the reaction of [Bi9O7(hfac)13] in methanol with a mixture of tBuPO3H2 and Eu(hfac)3·2H2O. Single-crystal Xray analysis shows that a hexanuclear [Bi6O8]2+ template cation is encapsulated within a cyclic europium(III) phosphonate cluster, [Eu 7 ( t BuPO 3 ) 7 ( t BuPO 3 H) 3 (hfac) 6 (CH 3 OH) 9 (H2O)2]2−, forming the structural framework of compound 3 (Figures 4 and 5). The central {Bi6O8} core is composed of

phosphonates. Of the six tert-butylphosphonates, two use the μ3-ligation mode to link the [Eu(hfac)(CH3OH)2], [Eu2(tBuPO3)2(hfac)2(CH3OH)], and [Bi6O8]2+ units, and the remaining four use the μ4-bridging mode to connect the [Eu(hfac)(CH 3 OH) 2 ], [Eu 3( tBuPO 3 ) 2 (hfac) 2 (CH3 OH) 4 (H2O)2], and [Bi6O8]2+ units. In the [Eu(hfac)(CH3OH)2] unit, the europium atom is coordinated by one hfac− ligand and two methanol molecules. The dimer [Eu2(tBuPO3)2(hfac)2(CH3OH)] consists of two europium atoms bridged by two tert-phosphonates. Each of the two europium atoms is further bound by one hfac− ligand. In the trinuclear [Eu3(tBuPO3)2(hfac)2(CH3OH)4(H2O)2] unit, the structure of the [Eu3(tBuPO3)2] moiety is identical with that found in 1Eu, with each tert-butylphosphonate ligand adopting a μ4bridging mode to coordinate to three europium and one bismuth atoms. The europium atoms in complex 3 are octaand heptacoordinated, while the bismuth atoms show three different ligancies: penta-, hexa-, and heptacoordination. Besides, the Eu−OP and Bi−OP bond lengths fall in the ranges of 2.230−2.580 and 2.320−2.890 Å in 3, respectively. Structure of Compound 4. The synthetic procedure used to obtain compound 4 is similar to that of 3, except that Eu(hfac)3·2H2O was replaced by Y(hfac)3·2H2O. Complex 4 occupies a crystallographic site of symmetry P3̅. Single-crystal X-ray analysis showed that 4 is composed of a hexanuclear [Bi6O8]2+ template cation and a cyclic nonanuclear yttrium(III) phosphonate cluster peripheral, [Y9(tBuPO3)12(hfac)6(CF3CO2)3(CH3OH)9(H2O)6]2− (Figures 6 and 7). The

Figure 4. Perspective view of Bi6Eu7(μ3-O)8(tBuPO3)7(tBuPO3H)3(hfac)6(CH3OH)9(H2O)2 in 3 with all hydrogen atoms omitted for clarity. The oxygen atoms of the [Bi6O8]2+ core are represented as pink spheres, and the remaining oxygen atoms in 3 are shown as red spheres.

Figure 6. Perspective view of Bi6Y9(μ3-O)4(μ3-OH)4(tBuPO3)12(hfac)6(CF3COO)3(CH3OH)9(H2O)6 in 4 with all hydrogen atoms omitted for clarity. The oxygen atoms of the [Bi6O8]2+ core are represented as pink spheres, and the remaining oxygen atoms in 4 are shown as red spheres.

Figure 5. (a) Peripheral anionic europium phosphonate cluster [Eu7(tBuPO3)7(tBuPO3H)3(hfac)6(CH3OH)9(H2O)2]2− in 3 with all hfac− ligands and water and methanol molecules omitted. (b) Hexanuclear [Bi6O8]2+ core in 3. The oxygen atoms of the [Bi6O8]2+ core are represented as pink spheres, and the remaining oxygen atoms in 3 are shown as red spheres.

structure of the {Bi6O8} moiety is identical with that found in 3, with six oxygen atoms binding to yttrium atoms. The Y− O bond lengths range from 2.288 to 2.411 Å. The central {Bi6O8} core is further stabilized by a cyclic nonanuclear yttrium phosphonate cluster consisting of three [Y3(tBuPO3)2(hfac)2(CF3CO2)(CH3OH)3(H2O)2] clusters that are symmetrically bridged by six phosphonates. Of the six tertbutylphosphonates, three adopt the μ3-η1,η1,η1-bridging mode to coordinate to two yttrium and one bismuth atoms, and the remaining three use the μ4-η1,η1,η2-ligation mode to connect two yttrium atoms with two bismuth atoms. Notably, the structure of the [Y3(tBuPO3)2] moiety is identical with that found in 1-Y, with each tert-butylphosphonate ligand adopting

three {Bi2O2} four-membered rings that are connected through two μ3-oxygen atoms with Bi−O bond lengths ranging from 2.130 to 2.340 Å; besides, it has a different structure compared with the common {Bi6O8} reported before.18 Six oxygen atoms from three {Bi2O2} four-membered rings are further bound to europium atoms with Eu−O bond lengths varying from 2.290 to 2.510 Å. On the other hand, the cyclic heptanuclear europium phosphonate cluster can be described as consisting of two [Eu(hfac)(CH3OH)2], one dimer [Eu2(tBuPO3)2(hfac)2(CH3OH)], and one trinuclear [Eu3(tBuPO3)2(hfac)2(CH3OH)4(H2O)2], which are bridged by six C

DOI: 10.1021/acs.inorgchem.8b02811 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry

bands at ca. 301, 310, and 312 nm, respectively. Nevertheless, 1-Pr in acetonitrile shows an absorption band at 305 nm. These absorption bands of complexes 1-RE are assigned as intraligand π−π* (hfac)19 compared with the absorption spectrum of Hhfac in a dichloromethane solution.20 Methanol solutions of complexes 2-Pr, 2-Sm, and 4 exhibit absorption bands at ca. 308, 258, and 303 nm, respectively. In an acetonitrile solution, complex 3 shows one obvious absorption band at 304 nm. Upon excitation under UV light of λ = 330 nm at room temperature, the emission spectrum of 1-Eu in methanol is recorded between λ = 500 and 650 nm (Figure 9), in which

Figure 7. (a) Peripheral anionic yttrium phosphonate cluster [Y9(tBuPO3)12(hfac)6(CF3CO2)3(CH3OH)9(H2O)6]2− in 4. All hfac− and CF3CO2− ligands and water and methanol molecules are omitted. (b) Hexanuclear [Bi6O8]2+ core in 4. The oxygen atoms of the [Bi6O8]2+ core are represented as pink spheres, and the remaining oxygen atoms in 4 are shown as red spheres.

a μ4-bridging mode to coordinate to three yttrium and one bismuth atoms. The Y−Op and Bi−Op bond lengths lie in the ranges of 2.206−2.380 and 2.280−2.785 Å respectively. The yttrium atoms are hepta- and octacoordinated in 4, while the bismuth atoms are penta- and hexacoordinated. The syntheses of 2−4 indicate that hybrid rare-earth(III)/ bismuth(III) clusters can be built up by a disassembly− reassembly solution process. It is remarkable that, in the presence of tBuPO3H2, the precursor of RE(hfac)3·2H2O undergoes a transformation to yield rare-earth(III) phosphonate building blocks, namely, [RE 2 ( t BuPO 3 ) 2 (hfac) 2 (CH3OH)2] and [RE3(tBuPO3)2(hfac)2(CH3OH)4(H2O)2], while the precursor of [Bi9O7(hfac)13] can be transformed into [Bi14O10(tBuPO3)10(tBuPO3H)2], [Bi12O10(tBuPO3)8(tBuPO3H)4]4−, and [Bi6O8]2+, which induce the formation of hybrid rare-earth(III)/bismuth(III)−oxo phosphonate clusters via RE−OP and Bi−OP bonding interactions. The importance of the [RE(hfac)3·2H2O]/[Bi9O7(hfac)13] ratio in the synthesis of hybrid rare-earth(III)/bismuth(III) clusters of 2−4 is highlighted. Type 2 was obtained in the reaction of tBuPO3H2 with a 9:2 mixture of [RE(hfac)3· 2H2O]/[Bi9O7(hfac)13] in methanol. If the ratio of rare-earth to bismuth precursors is 9:1, types 3 and 4 were isolated. Photophysical Properties. The UV−vis absorption data of complexes 1−4 are presented in Figure 8 and Table S1. In a methanol solution, 1-Eu, 1-Y, and 1-Sm display absorption

Figure 9. Fluorescence emission and excitation spectra of complexes 1-Eu and 3 in methanol and acetonitrile at room temperature, respectively.

two obvious characteristic emission bands at λ = 595 and 616 nm are attributed to 5D0 → 7F1 and 5D0 → 7F2 transitions, respectively, the characteristic fluorescence of the Eu3+ ion.21 It is well-known that the 5D0 → 7F1 emission is a magnetic-dipole transition and the 5D0 → 7F2 emission is an electric-dipole transition. The intensity of the 5D0 → 7F2 transition increases as the site symmetry of the Eu3+ ion decreases. As a consequence, the I(5D0→7F2)/I(5D0→7F1) intensity ratio often behaves as a criterion for examining the local symmetry of the Eu3+ ion.22 For 1-Eu, the red emission band at λ = 616

Figure 8. (a) UV−vis absorption spectra of complexes 1-Eu, 1-Y, 1-Pr, and 1-Sm at room temperature. (b) UV−vis absorption spectra of complexes of 2-Pr, 2-Sm, 3, and 4 at room temperature. D

DOI: 10.1021/acs.inorgchem.8b02811 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry

Synthesis of [Bi12RE2(μ3-O)10(tBuPO3)8(tBuPO3H)4(hfac)2(CH3OH)4]·xCH3OH·2H2O (2; RE = Pr, x = 4; RE = Sm, x = 6). Pr(hfac)3·2H2O (36 mg, 0.045 mmol) or Sm(hfac)3·2H2O (36 mg, 0.045 mmol) was dissolved in 20 mL of a methanol solution under stirring. Then Bi9O7(hfac)13 (46 mg, 0.01 mmol) and tBuPO3H2 (13 mg, 0.1 mmol) were added, and the mixture was stirred for 30 min. A pale-yellow solution was collected by filtration, and slow evaporation of the clear solution afforded the product as colorless crystals for 2-Pr and 2-Sm after 3 weeks, which were filtered and air-dried. Yield: ca. 21% for 2-Pr and ca. 25% for 2-Sm, based on Pr(hfac)3·2H2O and Sm(hfac)3·2H2O. Elem anal. Calcd for C66H150O60F12P12Bi12Pr2 (2Pr): C, 14.96; H, 2.83; F, 4.31; P, 7.03; Bi, 47.38; Pr, 5.33. Found: C, 14.75; H, 2.54; F, 4.05; P, 6.83; Bi, 47.05; Pr, 5.52. Elem anal. Calcd for C68H158O62F12P12Bi12Sm2 (2-Sm): C, 15.18; H, 2.94; F, 4.24; P, 6.92; Bi, 46.65; Sm, 5.58. Found: C, 14.85; H, 2.58; F, 4.05; P, 6.68; Bi, 46.39; Sm, 5.32. Synthesis of [Bi 6 Eu 7 (μ 3 -O) 8 ( t BuPO 3 ) 7 ( t BuPO 3 H) 3 (hfac) 6 (CH3OH)9(H2O)2]·CH3OH·CH3CN (3). The synthetic process of 3 is similar to that of compounds 2-Pr and 2-Sm, except that Eu(hfac)3· 2H2O (73 mg, 0.09 mmol) displaced Pr(hfac)3·2H2O (36 mg, 0.045 mmol) or Sm(hfac)3·2H2O (36 mg, 0.045 mmol) and 20 mL of CH3OH was replaced by 20 mL of a CH3OH/CH3CN mixture. Slow evaporation of the clear solution obtained at room temperature afforded the product as colorless crystals. Yield: ca. 27% for 3 based on Eu(hfac)3·2H2O. Elem anal. Calcd for C82H146O62NF36P10Bi6Eu7: C, 18.06; H, 2.68; N, 0.025; F, 12.55; P, 5.69; Bi, 23.01; Eu, 19.52. Found: C, 17.78; H, 2.43; N, 0.012; F, 12.32; P, 5.43; Bi, 22.85; Eu, 19.38. Synthesis of {[Bi 6 Y 9 (μ 3 -O) 4 (μ 3 -OH) 4 ( t BuPO 3 ) 12 (hfac) 6 (CF3COO)3(CH3OH)9(H2O)6]·6CH3OH·9H2O}·2CH3OH·17H2O (4). The synthetic process of 4 is also similar to that of 2-Pr and 2-Y, except that Y(hfac)3·2H2O (37 mg, 0.05 mmol) displaced Pr(hfac)3· 2H2O (36 mg, 0.045 mmol) or Sm(hfac)3·2H2O (36 mg, 0.045 mmol). Slow evaporation of the clear solution obtained at room temperature afforded the product as colorless crystals. Yield: ca. 25% for 4 based on Y(hfac) 3 ·2H 2 O. Elem anal. Calcd for C101H250O111F45P12Bi6Y9: C, 18.58; H, 3.83; F, 13.11; P, 5.70; Bi, 19.23; Y, 12.28. Found: C, 18.93; H, 3.55; F, 13.38; P, 5.42; Bi, 19.05; Y, 12.52.

nm from the 5D0 → 7F2 transition is the most prominent and the I(5D0→7F2)/I(5D0→7F1) intensity ratio is approximately 6.1:1, further demonstrating the low-symmetrical coordination environment of the Eu3+ ion. The excitation spectrum of 1-Eu in methanol is obtained by monitoring the emission of the Eu3+ ion at 616 nm, and an excitation peak at 322 nm is observed. Under 340 nm excitation, the fluorescence emission spectrum of complex 3 in an acetonitrile solution is determined (Figure 9), and the emission spectrum of complex 3 is similar to that of 1-Eu in spectral shape and band positions. In the emission spectrum of complex 3, two main emission peaks at 593 and 619 nm are displayed. For 3, the I(5D0→7F2)/ I(5D0→7F1) intensity ratio is approximately 14.5:1, and it shows a higher-symmetrical coordination environment of the Eu3+ ion than that of 1-Eu. The excitation spectrum of complex 3 in acetonitrile is obtained by monitoring the emission at 593 nm, and then one excitation peak at 324 nm is observed.

■

CONCLUSION In summary, we have synthesized and structurally characterized four trinuclear rare-earth phosphonate clusters and four unprecedented hybrid rare-earth/bismuth phosphonate clusters. Phosphonate is an effective bridging ligand to introduce the bismuth−oxo cluster into rare-earth−oxo or rare-earth/ bismuth−oxo phosphonate clusters. Type 1 represents the first well-characterized trinuclear rare-earth phosphonate cluster. Furthermore, complexes 2−4 provide precedents of bismuth− oxo clusters encapsulated by the cyclic rare-earth−oxo or rareearth/bismuth−oxo phosphonate clusters. It is interesting that complexes 1−4 exhibit obvious UV absorption; in addition, complexes 1-Eu and 3 emit bright-red fluorescence under UVlight excitation. The present study opens the way to synthetic studies of novel heterometallic clusters. New rare-earth− bismuth phosphonate clusters formed by other metals in lanthanides with novel structures are under exploration, and further work will focus on exploring the catalytic properties of bismuth phosphonate containing clusters.

■

■

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.8b02811.

EXPERIMENTAL SECTION

All reagents employed were commercially available and were used as received without further purification. Bi9O7(hfac)13 and RE(hfac)3· 2H2O (RE = Eu, Y, Pr, and Sm) were prepared according to the literature procedures.23,24 Synthesis of [RE3(tBuPO3)2(hfac)5(CH3OH)8]·2CH3OH (1; RE = Eu, Y, Pr, and Sm). Eu(hfac)3·2H2O (40 mg, 0.05 mmol), Y(hfac)3· 2H2O (37 mg, 0.05 mmol), Pr(hfac)3·2H2O (40 mg, 0.05 mmol), or Sm(hfac)3·2H2O (40 mg, 0.05 mmol) was dissolved in 20 mL of a methanol solution under stirring. Then tBuPO3H2 (13 mg, 0.1 mmol) was added, and the mixture was stirred for 20 min. A colorless solution was collected by filtration, and slow evaporation of the clear solution afforded the product as colorless crystals for 1-Eu, 1-Y, 1-Pr, and 1-Sm after about 2 weeks, which were filtered and air-dried. Yield: ca. 32% for 1-Eu, ca. 25% for 1-Y, ca. 22% for 1-Pr, ca. 28% for 1-Sm, based on RE(hfac)3·2H2O. Elem anal. Calcd for C43H63O26F30P2Eu3 (1-Eu): C, 24.77; H, 3.02; F, 27.36; P, 2.97; Eu, 21.89. Found: C, 24.48; H, 3.47; F, 27.05; P, 3.26; Eu, 21.67. Elem anal. Calcd for C43H63O26F30P2Y3 (1-Y): C, 27.24; H, 3.32; F, 30.08; P, 3.27; Y, 14.09. Found: C, 26.95; H, 3.57; F, 29.75; P, 3.02; Y, 14.23. Elem anal. Calcd for C43H63O26F30P2Pr3 (1-Pr): C, 25.16; H, 3.07; F, 27.79; P, 3.02; Pr, 20.63. Found: C, 24.87; H, 3.32; F, 27.53; P, 2.84; Pr, 20.35. Elem anal. Calcd for C43H63O26F30P2Sm3 (1-Sm): C, 24.82; H, 3.03; F, 27.42; P, 2.98; Sm, 21.64. Found: C, 24.57; H, 3.35; F, 27.15; P, 2.67; Sm, 21.39.

Materials characterization, X-ray crystallography, and Tables S1 and S2 (PDF) Accession Codes

CCDC 1850187−1850194 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing [email protected], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

■

AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected] (Y.-P.X.). *E-mail: [email protected] (X.L.). ORCID

Yun-Peng Xie: 0000-0002-4065-9809 Xing Lu: 0000-0003-2741-8733 Notes

The authors declare no competing financial interest. E

DOI: 10.1021/acs.inorgchem.8b02811 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry

■

Magnet Behavior for the Dy4 Analogue. Inorg. Chem. 2010, 49, 8067− 8072. (b) Zhou, G.-J.; Chen, W.-P.; Yu, Y.; Qin, L.; Han, T.; Zheng, Y.-Z. Filling the Missing Links of M3n Prototype 3d-4f and 4f Cyclic Coordination Cages: Syntheses, Structures, and Magnetic Properties of the Ni10Ln5 and the Er3 n Wheels. Inorg. Chem. 2017, 56, 12821− 12829. (c) Coletta, M.; McLellan, R.; Sanz, S.; Gagnon, K. J.; Teat, S. J.; Brechin, E. K.; Dalgarno, S. J. A New Family of 3d−4f BisCalix[4]arene-Supported Clusters. Chem. - Eur. J. 2017, 23, 14073− 14079. (8) Goura, J.; Chandrasekhar, V. Molecular Metal Phosphonates. Chem. Rev. 2015, 115, 6854−6965. (9) (a) Zheng, Y.-Z.; Evangelisti, M.; Tuna, F.; Winpenny, R. E. P. Co-Ln Mixed-Metal Phosphonate Grids and Cages as Molecular Magnetic Refrigerants. J. Am. Chem. Soc. 2012, 134, 1057−1065. (b) Zangana, K. H.; Pineda, E. M.; Schnack, J.; Winpenny, R. E. P. Octametallic 4f-Phosphonate Horseshoes. Dalton Trans. 2013, 42, 14045−14048. (10) (a) Rogow, D. L.; Fei, H.; Brennan, D. P.; Ikehata, M.; Zavalij, P. Y.; Oliver, A. G.; Oliver, S. R. J. Hydrothermal Synthesis of Two Cationic Bismuthate Clusters: An Alkylenedisulfonate Bridged Hexamer, [Bi6O4(OH)4(H2O)2][(CH2)2(SO3)2]3 and a Rare Nonamer Templated by Triflate, [Bi9O8(OH)6][CF3SO3]5. Inorg. Chem. 2010, 49, 5619−5624. (b) Andrews, P. C.; Busse, M.; Junk, P. C.; Forsyth, C. M.; Peiris, R. Sulfonato-encapsulated bismuth(III) oxidoclusters from Bi2O3 in water under mild conditions. Chem. Commun. 2012, 48, 7583−7585. (c) Mehring, M.; Mansfeld, D.; Paalasmaa, S.; Schürmann, M. Polynuclear Bismuth-Oxo Clusters: Insight into the Formation Process of a Metal Oxide. Chem. - Eur. J. 2006, 12, 1767− 1781. (11) Mehring, M. From Molecules to Bismuth Oxide-Based Materials: Potential Homo- and Heterometallic Precursors and Model Compounds. Coord. Chem. Rev. 2007, 251, 974−1006. (b) Sun, H.-T.; Zhou, J.; Qiu, J. Recent Advances in Bismuth Activated Photonic Materials. Prog. Mater. Sci. 2014, 64, 1−72. (12) Lin, Y.-F.; Chang, H.-W.; Lu, S.-Y.; Liu, C. W. Preparation, Characterization, and Electrophysical Properties of Nanostructured BiPO4 and Bi2Se3 Derived from a Structurally Characterized, SingleSource Precursor Bi[Se2P(OiPr)2]3. J. Phys. Chem. C 2007, 111, 18538−18544. (13) (a) Larsen, A.; Stoltenberg, M.; West, M. J.; Danscher, G. Influence of Bismuth on the Number of Neurons in Cerebellum and Hippocampus of Normal and Hypoxia-Exposed Mouse Brain: a Stereological Study. J. Appl. Toxicol. 2005, 25, 383−392. (b) Hollmann, M.; Boertz, J.; Dopp, E.; Hippler, J.; Hirner, A. V. Parallel onLine Detection of a Methylbismuth Species by Hyphenated GC/EIMS/ICP-MS Technique as Evidence for Bismuth Methylation by Human Hepatic cells. Metallomics 2010, 2, 52−56. (14) (a) Stavila, V.; Gulea, A.; Popa, N.; Shova, S.; Merbach, A.; Simonov, Y. A.; Lipkowski, J. A novel 3D Nd(III)−Bi(III) Coordination Polymer Generated from EDTA Ligand. Inorg. Chem. Commun. 2004, 7, 634−637. (b) Bachman, R. E.; Whitmire, K. H.; Thurston, J. H.; Gulea, A.; Stavila, O.; Stavila, V. Bismuth Ladder Polymers: Structural and Thermal Studies of [Bi(OCH2CH2)3N]n and [(BixTb1‑x(O2C2H2)3N·2H2O]n. Inorg. Chim. Acta 2003, 346, 249−255. (15) Duan, G.-X.; Xie, Y.-P.; Jin, J.-L.; Bao, L.-P.; Lu, X.; Mak, T. C. W. High-Nuclearity Heterometallic tert-Butylethynide Clusters Assembled with tert-Butylphosphonate. Chem. - Eur. J. 2018, 24, 6762−6768. (16) Li, H.-L.; Liu, Y.-J.; Liu, J.-L.; Chen, L.-J.; Zhao, J.-W.; Yang, G.-Y. Structural Transformation from Dimerization to Tetramerization of Serine-Decorated Rare-Earth-Incorporated Arsenotungstates Induced by the Usage of Rare-Earth Salts. Chem. - Eur. J. 2017, 23, 2673−2689. (17) Mehring, M.; Schürmann, M. The First Bismuth Phosphonate Cluster. X-Ray Single Crystal Structure of [(ButPO3)10(ButPO3H)2Bi14O10·3C6H6·4H2O]. Chem. Commun. 2001, 22, 2354−2355.

ACKNOWLEDGMENTS We gratefully acknowledge financial support by the National Natural Science Foundation of China (Grants 21201067, 51672093, and 51472095).

■

REFERENCES

(1) (a) Yam, V. W.-W.; Lo, W.-Y.; Lam, C.-H.; Fung, W. K.-M.; Wong, K. M.-C.; Lau, V. C.-Y.; Zhu, N. Synthesis and Luminescence Behavior of Mixed-Metal Rhenium(I)−Copper(I) and -Silver(I) Alkynyl Complexes. Coord. Chem. Rev. 2003, 245, 39−47. (b) Dolbecq, A.; Dumas, E.; Mayer, C. R.; Mialane, P. Hybrid Organic-Inorganic Polyoxometalate Compounds: From Structural Diversity to Applications. Chem. Rev. 2010, 110, 6009−6048. (c) Wang, Q.-M.; Lin, Y.-M.; Liu, K.-G. Role of Anions Associated with the Formation and Properties of Silver Clusters. Acc. Chem. Res. 2015, 48, 1570−1579. (d) Xie, Y.-P.; Jin, J.-L.; Duan, G.-X.; Lu, X.; Mak, T. C.W. High-Nuclearity Silver(I) Chalcogenide Clusters: A Novel Class of Supramolecular Assembly. Coord. Chem. Rev. 2017, 331, 54−72. (e) Wang, Z.; Su, H.-F.; Tan, Y.-Z.; Schein, S.; Lin, S.-C.; Liu, W.; Wang, S.-A.; Wang, W.-G.; Tung, C.-H.; Sun, D.; Zheng, L.S. Assembly of Silver Trigons into a Buckyball-like Ag180 Nanocage. Proc. Natl. Acad. Sci. U. S. A. 2017, 114, 12132−12137. (2) (a) Rao, X.; Song, T.; Gao, J.; Cui, Y.; Yang, Y.; Wu, C.; Chen, B.; Qian, G. A Highly Sensitive Mixed Lanthanide Metal-Organic Framework Self-Calibrated Luminescent Thermometer. J. Am. Chem. Soc. 2013, 135, 15559−15564. (b) Song, C.-Y.; Chai, D.-F.; Zhang, R.-R.; Liu, H.; Qiu, Y.-F.; Guo, H.-D.; Gao, G.-G. A silver-alkynyl cluster encapsulating a fluorescent polyoxometalate core: enhanced emission and fluorescence modulation. Dalton Trans. 2015, 44, 3997−4002. (c) Chow, C. Y.; Eliseeva, S. V.; Trivedi, E. R.; Nguyen, T. N.; Kampf, J. W.; Petoud, S.; Pecoraro, V. L. Ga3+/Ln3+ Metallacrowns: A Promising Family of Highly Luminescent Lanthanide Complexes That Covers Visible and Near-Infrared Domains. J. Am. Chem. Soc. 2016, 138, 5100−5109. (3) (a) Zangana, K. H.; Pineda, E. M.; Schnack, J.; Winpenny, R. E. P. Octametallic 4f-Phosphonate Horseshoes. Dalton Trans. 2013, 42, 14045−14048. (b) Li, Y. Y.; Gao, F.; Beves, J. E.; et al. A giant metallo-supramolecular cage encapsulating a single-molecule magnet. Chem. Commun. 2013, 49, 3658−3660. (c) Zheng, X.-Y.; Kong, X.-J.; Zheng, Z.; Long, L.-S.; Zheng, L.-S. High-Nuclearity LanthanideContaining Clusters as Potential Molecular Magnetic Coolers. Acc. Chem. Res. 2018, 51, 517−525. (4) (a) Wei, N.; Zuo, R.-X.; Zhang, Y.-Y.; Han, Z.-B.; Gu, X.-J. Robust High-Connected Rare-Earth MOFs as Efficient Heterogeneous Catalysts for CO2 Conversion. Chem. Commun. 2017, 53, 3224−3227. (b) Li, S.; Zhou, Y.; Peng, Q.; Wang, R.; Feng, X.; Liu, S.; Ma, X.; Ma, N.; Zhang, J.; Chang, Y.; Zheng, Z.; Chen, X. Controllable Synthesis and Catalytic Performance of Nanocrystals of Rare-Earth-Polyoxometalates. Inorg. Chem. 2018, 57, 6624−6631. (5) (a) Evangelisti, M.; Roubeau, O.; Palacios, E.; Camón, A.; Hooper, T. N.; Brechin, E. K.; Alonso, J. J. Cryogenic Magnetocaloric Effect in a Ferromagnetic Molecular Dimer. Angew. Chem., Int. Ed. 2011, 50, 6606−6609. (b) Peng, J.-B.; Kong, X.-J.; Zhang, Q.-C.; Orendác,̌ M.; Prokleška, J.; Ren, Y.-P.; Long, L.-S.; Zheng, Z.; Zheng, L.-S. Beauty, Symmetry, and Magnetocaloric Effect−Four-Shell Keplerates with 104 Lanthanide Atoms. J. Am. Chem. Soc. 2014, 136, 17938−17941. (6) (a) Zhou, Y.; Zheng, X.-Y.; Cai, J.; Hong, Z.-F.; Yan, Z.-H.; Kong, X.-J.; Ren, Y.-P.; Long, L.-S.; Zheng, L.-S. Three Giant Lanthanide Clusters Ln37 (Ln = Gd, Tb, and Eu) Featuring A DoubleCage Structure. Inorg. Chem. 2017, 56, 2037−2041. (b) Zheng, X.-Y.; Jiang, Y.-H.; Zhuang, G.-L.; Liu, D.-P.; Liao, H.-G.; Kong, X.-J.; Long, L.-S.; Zheng, L.-S. A Gigantic Molecular Wheel of {Gd140}: A New Member of the Molecular Wheel Family. J. Am. Chem. Soc. 2017, 139, 18178−18181. (7) (a) Abbas, G.; Lan, Y.; Kostakis, G. E.; Wernsdorfer, W.; Anson, C. E.; Powell, A. K. Series of Isostructural Planar Lanthanide Complexes [LnIII4(μ3-OH)2(mdeaH)2(piv)8] with Single Molecule F

DOI: 10.1021/acs.inorgchem.8b02811 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry (18) Miersch, L.; Rüffer, T.; Schlesinger, M.; Lang, H.; Mehring, M. Hydrolysis Studies on Bismuth Nitrate: Synthesis and Crystallization of Four Novel Polynuclear Basic Bismuth Nitrates. Inorg. Chem. 2012, 51, 9376−9384. (19) Xu, H.-B.; Zhong, Y.-T.; Zhang, W.-X.; Chen, Z.-N.; Chen, X.M. Syntheses, Structures and Photophysical Properties of Heterotrinuclear Zn2Ln clusters (Ln = Nd, Eu, Tb, Er, Yb). Dalton Trans. 2010, 39, 5676−5682. (20) De Silva, C. R.; Wang, R.; Zheng, Z. Highly luminescent Eu(III) complexes with 2,4,6-tri(2-pyridyl)-1,3,5-triazine ligand: Synthesis, structural characterization, and photoluminescence studies. Polyhedron 2006, 25, 3449−3455. (21) Gao, B.; Zhang, W.; Zhang, Z.; Lei, Q. Preparation of Polymer−Rare Earth Complex Using Salicylic Acid-Containing Polystyrene and Its Fluorescence Emission Property. J. Lumin. 2012, 132, 2005−2011. (22) (a) Zhang, T.; Spitz, C.; Antonietti, M.; Faul, C. F. J. Highly Photoluminescent Polyoxometaloeuropate-Surfactant Complexes by Ionic Self-Assembly. Chem. - Eur. J. 2005, 11, 1001−1009. (b) Cui, Y.; Yue, Y.; Qian, G.; Chen, B. Luminescent Functional Metal-Organic Frameworks. Chem. Rev. 2012, 112, 1126−1162. (23) Dikarev, E. V.; Zhang, H.; Li, B. From a Bismuth Oxido Diketonate to a Giant Bismuth Oxido Cluster. Angew. Chem., Int. Ed. 2006, 45, 5448−5451. (24) Richardson, M. F.; Wagner, W. F.; Sands, D. E. Rare-Earth Trishexafluoroacetylacetonates and Related Compounds. J. Inorg. Nucl. Chem. 1968, 30, 1275−1289.

G

DOI: 10.1021/acs.inorgchem.8b02811 Inorg. Chem. XXXX, XXX, XXX−XXX