DSpace at VNU: Novel Lanthanide(III) Ternary Complexes with Naphthoyltrifluoroacetone: A Synthetic and Spectroscopic Study

gands may enhance luminescence intensities.[5]Therefore, an-cillary ligands of 2,2 ⬘-bipyridine and o-phenanthroline type have been extensively used.[4,6–9]Nonetheless, much attention ha

DOI: 10.1002/zaac.201500158

Novel Lanthanide(III) Ternary Complexes with Naphthoyltrifluoroacetone:

A Synthetic and Spectroscopic Study Thi-Nguyet Trieu,*[a]Thi-Hien Dinh,[a,b] Hung-Huy Nguyen,[a] Ulrich Abram,[c] and

Keywords: Lanthanide complexes; Bipyridine N-oxide; β-Diketonate; X-ray structure

Abstract A series of lanthanide complexes with general formula

[Ln(NTA)3X] were prapared [Ln = Y (a), Er (b), Eu (c), NTA =

naphthoyltrifluoroacetone, X = H2O (1), phen = phenanthroline (2),

bpyO1 = 2,2⬘-bipyridine N-oxide (3), and bpyO2 =

2,2⬘-bipyridine-N,N⬘-dioxide (4)] The crystal structures of [Eu(NTA)3bpyO2] (4b),

[Er(NTA)3bpyO1] (3c), and [Er(NTA)3phen] (2c) were determined

X-Introduction

The lanthanide β-diketonates have attracted much attention,

due partially to their facile syntheses, but mainly to their

intri-guing properties spanning from magnetism to

photolumines-cence.[1]In recent years, the design of lanthanide β-diketonates

has been directed towards applications in optical devices,

lumi-nescence sensors for chemical species, fluorescent lighting and

electroluminescent devices.[2–4] The luminescence is

lantha-nide-centered but not able to be obtained in good yield by

direct excitation as 4f–4f transition is Laporte-forbidden The

strategy to achieve lanthanide emission includes the use of

β-diketone ligands, which exert stable chelation with Ln3+ions

and strong π–π* absorption The ligand in its excited state, as

an antenna, may undergo effective energy transfer to Ln3+ion,

thus switching on the Ln3+emission.

The syntheses of lanthanide β-diketonates typically in the

first step involve formation of the complexes with two

crystal-water molecules coordinating to the central metal atom

Unfor-tunately, the quenching of lanthanide emission by O–H

sketches in water is rather effective It is well-known that

re-placement of the coordinated water by ancillary chelating

li-* Dr T.-N Trieu

Fax: +84-4382-41140

E-Mail: nguyetdhkhtn@gmail.com

* Dr M.-H Nguyen

E-Mail: nmhai@vnu.edu.vn

[a] Department of Chemistry

Hanoi University of Science

19 Le Thanh Tong

Hanoi, Vietnam

[b] Department of Chemistry

Hanoi National University of Education

136 Xuan Thuy

Hanoi, Vietnam

[c] Institute of Chemistry and Biochemistry

Freie Universität Berlin

Fabeckstr 34/36

14195 Berlin, Germany

ray crystallographic analysis reveals that the complexes are of mono-nuclear structure with three NTA and one ancillary ligand The

photo-luminescence spectra of 3c and 4b exhibit strong characteristic

emis-sions arising from Eu3+central ion due to the efficient sensitization of bpyO1 and bpyO2, respectively

gands may enhance luminescence intensities.[5]Therefore, an-cillary ligands of 2,2 ⬘-bipyridine and o-phenanthroline type

have been extensively used.[4,6–9]Nonetheless, much attention has not been paid to their N-oxide derivatives such as bpyO1 and bpyO2.[10–12]The compounds may serve as excellent

li-gands towards Ln3+due to the presence of hard O donor atom

as well as efficient sensitizers for the lanthanide emis-sion.[1,13,14]

In the presented work, we describe the syntheses, crystal structures and emission properties of a series of lanthanide (Y3+, Er3+, Eu3+) ternary complexes containing naphthoyltri-fluoroacetone (NTA) (Scheme 1) and various ancillary ligands (Scheme 2) Our results showed that bpyO1 and bpyO2 can

Scheme 1 General formula of lanthanide complexes discussed in this

work

Scheme 2 The ancillary ligands used in this work.

bind strongly to the Ln3+and sensitize efficiently the

character-istic red emission of Eu3+.

Results and Discussion

Synthesis and Characterization

The ternary complexes 2–4 [Ln(NTA)3X] were synthesized

by reacting 1 [Ln(NTA)3(H2O)2] (Ln = Y, Er, Eu) with relevant

ancillary ligands (X) (Scheme 3) in a 1:1 ratio The

displace-ment of H2O by the ligands occurs readily as H2O is a weak

coordinating solvent and chelating effect also favors the

substi-tution There were dramatic changes in solubility of the

com-plexes upon the substitution of polar fragment H2O by

rela-tively non-polar moieties such as phen, bpyO1, and bpyO2.

Consequently, [Ln(NTA)3(H2O)2] are highly soluble in

meth-anol, whereas 2–4 can be well dissolved in chloroform This

may serve as a good indication that the reaction in chloroform

is complete when [Ln(NTA)3(H2O)2] solids disappear.

Scheme 3 Syntheses of the complexes 2, 3, and 4.

The complexes were characterized by infra-red

spec-troscopy, 1H and13C NMR spectroscopy, mass spectrometry

(MALDI-TOF), and elemental analysis The elemental analysis

results reveal the correct formulation of the complexes,

im-plying the presence of three NTA ligands, one ancillary ligands

and one central metal ion The IR spectra of 1 all shows

char-acteristic broad bands in the 3000–3500 cm–1 region, which

are in line with the presence of the water coordinated to the

metal ion The disappearance of the bands in the IR spectra of

2–4 confirms that the water molecules were displaced by

bi-dentate ligands The absorption at 1601 cm–1, which is typical

for C=O sketch in the ligand is hypsochromically shifted to

1608–1615 cm–1in the complexes It might be due to the

delo-calization of π electrons among the diketonate moiety and

naphthalene ring upon complexation The sketching frequency

of N–O bonds in free bpyO1 and bpyO2 are 1252 and

1255 cm–1, respectively.[17,18] The bands are shifted to lower

wave numbers in 3 and 4 (1193 and 1196 cm–1), thus

confirm-ing the complexation of Ln3+ ion with bpyO1 and bpyO2 li-gands through oxygen atoms.

The study of rare earth complexes by NMR spectroscopy is often limited due to the paramagnetism of the metal ions ex-cept for YIII Hence, it is reasonable to investigate the NMR spectroscopy of YIIIcomplexes as representatives for the con-geners of other metal ions The1H NMR spectra of the com-plexes display singlet signals at 6.4–6.6 ppm, which are re-sponsible for the methine proton of diketonate moiety of NTA ligand (Ha) The overlapping signals in the region 7.3–8.4 ppm are common for aromatic protons of naphthalene rings No-tably, the H1 resonances were found in lower field regions (8.3–8.4 ppm) This fact is reasonable given the steric repul-sion (peri effect) between H1and H8 In the1H-NMR spectrum

of 1a, the proton signal of water was not observed due to its rapid exchange with MeOD For 2–4a, the presence of phen,

bpyO1, and bpyO2 is evidenced by an extra set of signals in the aromatic region in addition to those of the napthalene rings.

The integral ratios suggest the complex composition is of three NTA and one ancillary ligand The 13C NMR spectrum of 1

exhibits the two most downfield signals at 188–189 ppm and 171–172 ppm, which are ascribable to two C=O groups While the former is a singlet, the latter is a quartet arising from spin coupling between13C and19F nuclei (3JC,F= 127 Hz) Another resonance, which is common to –CF3 appears as quartet at 119–120 ppm (2JC,F= 1135 Hz) The CH group of diketonate fragment gives a singlet at 92–93 ppm, confirming the forma-tion of chelate ring with metal ion The signals in the region 120–153 ppm are typical for aromatic carbons of naphthalene rings and ancillary ligands.

X-ray Structural Characterization

The structures of 2c, 3c, and 4b were determined by

single-crystal X-ray diffraction (Figure 1, Figure 2, and Figure 3) Se-lected bond lengths and angles are provided in Table 1 Crystal data and data collection parameters for the complexes are given in Table 2.

Table 1 Selected bond lengths /Å and angles /° for complexes 2c, 3c, and 4b.

Ln–O1 2.313(4) 2.299(5) 2.379(7)

Ln–O2 2.296(4) 2.305(5) 2.335(7)

Ln–O3 2.310(5) 2.295(5) 2.378(8)

Ln–O4 2.314(4) 2.325(5) 2.407(8)

Ln–O5 2.323(4) 2.311(5) 2.368(7)

Ln–O6 2.274(4) 2.293(5) 2.374(7)

Ln–X1a) 2.519(5) 2.594(6) 2.467(6)

Ln–X2a) 2.555(5) 2.313(5) 2.343(7)

X1–Ln–X2a) 64.9(2) 67.5(2) 69.4(3)

a) X1, X2= donor atom of the ancillary ligands

Figure 1 (a) ORTEP plot of 2c (thermal ellipsoids drawn at the 50 %

probability level) Hydrogen atoms are omitted for clarity Color

scheme: Er, green; F, yellow; C, gray; N, pale blue (b)π–π

interac-tions in 2c.

Figure 2 ORTEP plot of 3c (thermal ellipsoids drawn at the 50 %

probability level) Hydrogen atoms are omitted for clarity Color

scheme: Er, green; F, yellow; C, gray; N, pale blue

The structures of the complexes reveal a coordination

number 8 of each central metal ion, in which Ln3+are bonded

to six oxygen atoms from three NTA and two donor atoms (X1,

X2) from the ancillary ligands, namely, N, N for phen, N, O

for bpyO1, O, O for bpyO2 The coordinating atoms form a

distorted square antiprism, which consists of two square facets.

In each facet four donor atoms are (X1, X2, O5, O6) and (O1,

Figure 3 (a) ORTEP plot of 4b (thermal ellipsoids drawn at the 50 %

probability level) Hydrogen atoms are omitted for clarity Color scheme: Eu, green; F, yellow; C, gray; N, pale blue (b), (c)π–π

inter-actions in 4b.

O2, O3, O4), respectively The Ln–O bond lengths (2.274–

2.467 Å) and O–Ln–O angles (70.6–72.8°) are similar to

re-ported values in literature.[9,19] Notably, the C–C and C–O bonds in the diketonate moiety are in the ranges between

car-Table 2 Crystal data and structure refinement for complexes 2c, 3c, and 4b.

Independent reflections 14114 [R(int) = 0.0485] 9047 [R(int) = 0.1484] 9568 [R(int) = 0.0875]

R1 /wR2[I⬎ 2σ (I)] R1 = 0.0701, wR2= 0.1774 R1 = 0.0476, wR2= 0.1502 R1 1 = 0 0510, wR2= 0 0683

bon–carbon and carbon–oxygen single and double bonds,

respectively This again confirms the delocalization of π

elec-trons in diketonate moiety upon complexation, which is

consis-tent with IR results.

For 3c and 4b, the formation of six- and seven-membered

chelate rings leads to the staggered conformations of aromatic

rings in bpyO1 and bpyO2 moieties The dihedral angles of

the rings are 42.9° and 56.0°, respectively In addition, the

X1–Ln–X2 bite angle in 4b (69.4°) was found larger than that

in 3c (67.5°) The N–O bond lengths (1.303–1.349 Å) lie in

the normal range of N-oxide metal complexes.[11,17,18]

Interestingly, compounds 2c and 4b exhibit large π–π

stack-ing in solid state (Figure 1b and Figure 3c) 2c shows the

over-lap mainly between naphthalene ring and diketonate moiety of

adjacent molecules The two head-to-tail overlapped

naphthal-ene rings in 4b are offset along long axes of the rings The

overlap area is up to 60 % Also, π–π interactions are detected

between naphthalene and pyridine N-oxide fragments The

separations of the rings in the stacking are 3.299 Å (2c),

3.435 and 3.330 Å (4b), falling in the range of π–π

interac-tions.[20–22]

Absorption and Emission Spectra

The absorption spectra of 3b and 4b in CHCl3solution are

displayed in Figure 4 The spectroscopic data are summarized

in Table 3 The broad bands observed at 336 and 337 nm are

ascribable to singlet-singlet π–π* enolic transition arising from

β-diketonate fragment.[23]The absorption maxima are slightly

red-shifted 540 cm–1 in comparison with that of the free

Table 3 Absorption and emission spectroscopic data of the compounds.

NTA,[3]suggesting the perturbation of the Eu3+upon complex-ation The bands at lower wavelength around 260 nm are naphthalene-centered π–π* transition The absorption of N-ox-ide ligands coincN-ox-ides with the naphthalene feature The extinc-tion coefficient values of the complexes are much larger than that of the free NTA (about three times), indicating, therefore, the presence of three NTA in the complexes.

Figure 4 Absorption spectra of 3b and 4b in CHCl3at room tempera-ture

Figure 5 shows the emission spectra of 3b and 4b in CHCl3 The excitation spectra of the complexes are similar to relevant absorptions in the 250–400 nm region (Figure 6) The result is reasonable in light of the energy transfer from the ligands to

Eu3+ion, to which the bands around 270 nm indicate the

con-tribution of bipyridine oxides (Figure 7) The absence of

ab-sorption band arising from 4f-4f transition of the Eu3+ion

fur-ther confirms the efficient sensitization Upon excitation at

324 nm, the complexes give the typical Eu3+ emission lines

assigned to5D0씮7F0–4transitions, of which5D0씮7F2

tran-sition at 614 nm is the strongest emission.[24]This

hypersensi-tive transition which is of electric dipole in nature is much

more intense than the magnetic 5D0 씮 7F1 transition at 592

and 595 nm The large intensity ratios IED/IMDof the two

tran-sitions which are 8.86 for 3b and 10.98 for 4b clearly validate

the low Eu3+local symmetry, namely, the absence of inversion

center in the complexes.

Figure 5 Emission spectra of 3b and 4b in CHCl3at room

tempera-ture Excitation wavelength = 324 nm The5D0씮 7D0–4transitions

are indicated

Figure 6 Excitation spectra of 3b and 4b in CHCl3at room

tempera-ture Emission wavelength = 614 nm

Displacement of the coordinated water in 1b by strong

che-lating bpyO1 and bpyO2 in 3b and 4b significantly enhance

the luminescent intensities It is well-documented that phen is

able to efficiently sensitize Eu3+ion.[25,26]Indeed, the emission

quantum yields of 3b (0.12) and 4b (0.17) are comparable to

that of 2b (0.40) Hence, this fact affirms significant antenna

effect of bpyO1 and bpyO2 Also, stronger emission of 4b

might serve as a good indication that seven-membered chelate

ring by bpyO2 is more rigid than six-membered chelate ring

by bpyO1.

Figure 7 Absorption spectra of bpyO1 and bpyO2 in ethanol at room

temperature

Conclusions

A series of lanthanide complexes with NTA ligands were synthesized with the ancillary ligands being varied The X-ray structures reveal six- and seven-membered chelate rings of bpyO1 and bpyO2 with lanthanide ions The Eu3+complexes

of the ligands are strongly emissive in red region The good emission quantum yields implied comparable antenna effects

of bpyO1 and bpyO2 to that of phen Ongoing studies about coordination chemistry of such N-oxide ligands with lantha-nide ions are presently underway in our laboratories.

Experimental Section

General Methods: All the solvents used for synthesis and

spectro-scopic measurements were purified according to literature procedures

1,10-Phenanthroline monohydrate (phen) (99 %, ACROS Organics), 2,2’-bipyridine N-oxide (bpyO1) (98 %, Sigma-Aldrich) and 2,2

⬘-bi-pyridine N,N⬘-dioxide (bpyO2) (98%, Sigma-Aldrich) were used as received without further purification

Physical Methods: The FT-IR spectra of the complexes were

mea-sured with a FT-IR 8700 infrared spectrophotometer (4000–400 cm–1)

in KBr pellets The 1H NMR spectra were recorded with a Bruker-500MHz spectrometer in CDCl3solution at 300 K Elemental analysis

of carbon, hydrogen, and nitrogen was determined with a Heraeus va-rio EL elemental analyzer MALDI-TOF-MS spectra were recorded with a Bruker Daltonics UltrafleXtreme spectrometer using α-Cyano-4-hydroxycinnamic acid as matrix

Spectroscopic Measurements: Absorption and emission spectra of

the complexes were measured in chloroform at room temperature on Cary 5000 UV/Vis spectrometer and fluorescence spectrophotometer

Rhodamine 640 was used as emission quantum yield standard

The syntheses of 1b, 1c, and 2b have been reported elsewhere.[6–8]

Synthesis of [Y(NTA) 3 (H 2 O) 2 ] (1a): To an ethanol solution (60 mL)

of NTA (0.6 mmol) and NaOH (0.6 mmol) was added YCl3·6H2O (0.2 mmol) The resulting mixture was stirred for 24 h at room tem-perature and CCl4(10 mL) was added to afford a white solid The product was washed by a large amount of CCl4and air-dried Yield:

136 mg, 74 % IR (KBr):ν˜ = 3404 (m), 3064 (w), 1613 (s), 1566 (s),

1530 (m), 1460 (m), 1293 (s), 1197 (s), 1143 (s), 962 (m), 801 (s),

692 (m), 571 (m), 457 (s) cm–1.1 H NMR (MeOD):δ = 8.54 (s, 3 H,

H1, naphthyl), 8.06 (d, J = 8.5 Hz, 3 H, H4, naphthyl), 7.86 (d, J =

8.0 Hz, 3 H, H8, naphthyl), 7.81 (d, J = 8.5 Hz, 3 H, H3, naphthyl),

7.65 (d, J = 7.0 Hz, 3 H, H5, naphthyl), 7.54 (t, J = 7.5 Hz, 3 H, H7,

naphthyl), 7.40 (t, J = 7.5 Hz, 3 H, H6, naphthyl), 6.67 (s, 3 H, CH).

13 C NMR (MeOD):δ = 189.6 (s, C=O), 172.5 (q, 3JC,F= 127 Hz,

C=O), 137.0–125.2 (naphthyl), 120.7 (q,2JC,F = 1135 Hz, CF3), 93.3

(s, CH) C42H28F9O8Y: calcd C 54.80; H, 3.07 %; found: C 54.32; H

3.21 %

Syntheses of [Y(NTA) 3 phen] (2a) and [Er(NTA) 3 phen] (2c): A

solu-tion of phen (0.1 mmol) in methanol (5 mL) was added dropwise to a

solution of 1 (0.1 mmol) in methanol (15 mL) The mixture was heated

to 60 °C and stirred for 4 h, then filtered, washed with methanol, and

last dried in vacuo to give product in good yields Single crystals of

complexes were harvested in about two weeks by recrystallization

from chloroform/hexane 2a and 2c were also prepared using another

method: Phen (0.1 mmol) and 1 (mmol) were suspended in chloroform

(10 mL) The mixture was stirred for 2 h and the suspension

com-pletely disappeared The solvent was reduced to 1 mL and excess

hex-ane was added to afford the title products

2a: Yield: 84 % IR (KBr): ν˜ = 3067 (w), 1611 (s), 1529 (s), 1478

(m), 1301 (s), 1191 (s), 1137 (s), 796 (s), 582 (m), 477 (m) cm–1.1 H

NMR (CDCl3):δ = 9.78 (d, J = 3.5 Hz, 2 H, Hd, phen), 8.40 (s, 3 H,

H1, naphthyl), 8.30 (d, J = 8.0 Hz, 2 H, Hb, phen), 7.92 (d, J = 8.0 Hz,

3 H, H5, naphthyl), 7.80–7.71 (m, 13 H, H3,4,8, naphthyl, Ha,c, phen),

7.50 (t, J = 7.5 Hz, 3 H, H7, naphthyl), 7.44 (t, J = 7.0 Hz, 3 H, H6,

naphthyl), 6.47 (s, 3 H, CH).13 C NMR (CDCl3):δ = 188.1 (s, C=O),

171.6 (q, C=O), 151.4–120.3 (m, naphthyl, phen), 119.2 (q, CF3), 92.5

(s, CH) C54H32F9N2O6Y: calcd C 60.91; H 3.03; N 2.63 %; found: C

60.42; H 2.82; N 2.74 % MALDI-TOF-MS: m/z 1165.1, [M + H]+

2c: Yield : 78 % IR (KBr):ν˜ = 3065 (w), 1608 (s), 1531 (s), 1301

(m), 1190 (s), 1135 (s), 960 (m), 797 (s), 576 (m), 474 (m) cm–1

C54H32F9N2O6Er: calcd C 56.74; H 2.82, N 2.45 %; found: C 56.32;

H 3.01; N 2.65 % MALDI-TOF-MS: m/z 1144.1, [M + H]+

Syntheses of [Y(NTA) 3 bpyO1] (3a), [Eu(NTA) 3 bpyO1] (3b), and

[Er(NTA) 3 bpyO1] (3c): The compounds were prepared following the

procedures for 2, except that 2,2⬘-bipyridine N-oxide was used instead

of phen X-ray-quality crystals of 3c were obtained by slow

evapora-tion of chloroform soluevapora-tion at room temperature

3a: Yield: 64 % IR (KBr): ν˜ = 3060 (w), 1613 (s), 1529(m), 1474

(m), 1303 (s), 1190 (s), 1127 (s), 956 (m), 791 (s), 688 (m), 575 (m),

468 (m) cm–1.1 H NMR (CDCl3):δ = 9.58 (s, 1 H, Ha, bpyO1), 8.90

(s, 1 H, Ha’, bpyO1), 8.32 (s, 3 H, H1, naphthyl), 7.85 (d, J = 8.5 Hz,

3 H, H5, naphthyl), 7.76–7.46 (m, 18 H, H3,4,7,8naphthyl, Hb,c,d,b’,c’,d’,

bpyO1), 7.39 (t, J = 7.0 Hz, 3 H, H6, naphthyl), 6.42 (s, 3 H, CH).

13 C NMR (CDCl3)δ = 188.0 (s, C=O), 171.0 (q, C=O), 151.0–124.3

(m, naphthyl, bpyO1), 121.0 (q, CF3), 92.6 (s, CH) C52H32YF9N2O7:

calcd C 59.10; H, 3.05; N, 2.65 %; found: C 59.20; H 3.15; N 2.95 %

MALDI-TOF-MS: m/z 1057.1, [M + H]+

3b: Yield: 76 % IR (KBr):ν˜ = 3055 (w), 1613 (s), 1526 (m), 1463

(m), 1297 (s), 1193 (s), 1136 (s), 958 (m), 791 (s), 685 (m), 573 (m),

477 (m) cm–1 C52H32EuF9N2O7: calcd C 55.78; H, 2.88; N, 2.50 %;

found: C 56.00; H, 2.62; N, 2.92 % MALDI-TOF-MS: m/z 1121.1,

[M + H]+

3c: Yield: 70 % IR (KBr):ν˜ = 3058 (w), 1614 (s), 1534 (m), 1470

(m), 1300 (s), 1190 (s), 1132 (s), 960 (m), 797 (s), 684 (m), 574 (m),

475 (m) cm–1 C52H32ErF9N2O7: calcd C 55.02; H, 2.84; N, 2.47 %;

found: C 55.54; H 2.72; N 2.74 % MALDI-TOF-MS: m/z 1136.1, [M

+ H]+

Syntheses of [Y(NTA) 3 bpyO2] (4a), [Eu(NTA) 3 bpyO2] (4b), and [Er(NTA) 3 bpyO2] (4c): The compounds were prepared following the procedures for 2, except that 2,2⬘-bipyridine N,N⬘-dioxide was used instead of phen X-ray-quality crystals of 4b were obtained by slow

diffusion of ethanol/hexane solution at room temperature

4a: Yield: 74 % IR (KBr):ν˜ = 3058 (w), 1621 (s), 1530 (m), 1429 (m), 1300 (s), 1127 (s), 795 (s), 685 (m), 572 (m), 434 (m) cm–1.1 H NMR (CDCl3): 8.56 (d, 2 H, Ha, bpyO2), 8.40 (s, 3 H, H1, naphthyl),

7.94 (d, J = 7.5 Hz, 3 H, H5, naphthyl), 7.80–7.59 (m, 16 H, H3,4,8 naphthyl, Hb,c, bpyO2), 7.50 (t, J = 7.0 Hz, 3 H, H7, naphthyl), 7.39

(t, J = 7.5 Hz, 3 H, H6, naphthyl), 6.48 (s, 3 H, CH). 13 C NMR

(CDCl3):187.4 (s, C=O), 171.0 (q, C=O), 142.6–126.9 (m, naphthyl, bpyO2), 125.0 (q, CF3), 91.9 (s, CH) C52H32YF9N2O8: calcd C 59.10;

H 3.05; N 2.65 %; found: C 59.33; H 3.16; N 2.73 %

MALDI-TOF-MS: m/z 1073.1, [M + H]+

4b: Yield: 76 % IR (KBr):ν˜ = 3062 (w), 1610 (s), 1527 (m), 1472 (m), 1298 (s), 1196 (s), 1131 (s), 794 (s), 682 (m), 575 (m), 476 (m)

cm–1 C52H32EuF9N2O8: calcd C 55.49; H 2.84; N 2.47 %; found: C

55.19; H 2.68; N 2.57 % MALDI-TOF-MS: m/z 1137.1, [M + H]+

4c: Yield: 68 % IR (KBr):ν˜ = 3060 (w), 1617 (s), 1303 (s), 959 (m),

574 (m) cm–1 C52H32ErF9N2O8: calcd C 54.26; H 2.80; N 2.43 %;

found: C 54.45; H 2.81; N 2.55 % MALDI-TOF-MS: m/z 1152.1, [M

+ H]+

X-ray Crystallography: The intensities for the X-ray determinations

were collected with a Bruker D8 Quest instrument with Mo-Kα radia-tion (λ = 0.71073 Å) Standard procedures were applied for data

re-duction and absorption correction Structure solution and refinement were performed with SHELXS97 and SHELXL97 programs.[15]

Hydrogen atom positions were calculated for idealized positions and treated with the “riding model” option of SHELXL Two chlorine

atoms of disordered chloroform in 2c were refined isotropically The naphthalene ring in 3c occupies two positions with occupancy ratios

of 64:36 A highly disordered solvent in 4b was treated by the

SQUEEZE option in PLATON.[16]

Crystallographic data (excluding structure factors) for the structures in this paper have been deposited with the Cambridge Crystallographic Data Centre, CCDC, 12 Union Road, Cambridge CB21EZ, UK

Copies of the data can be obtained free of charge on quoting the

depository numbers CCDC-1051791 (2c), CCDC-1051790 (3c),

and CCDC-1051789 (4b) (Fax: +44-1223-336-033; E-Mail:

deposit@ccdc.cam.ac.uk, http://www.ccdc.cam.ac.uk)

Acknowledgements

Vietnam’s National Foundation for Science and Technology Develop-ment is thanked for financial support (Grant No 104.02–2011.31)

References

[1] D A Atwood, The Rare Earth Elements: Fundamentals and

Ap-plications, Wiley, Chichester, 2012.

[2] Z Li, J Yu, L Zhou, H Zhang, R Deng, Z Guo, Org Electron.

2008, 9, 487.

[3] J Yu, H Zhang, L Fu, R Deng, L Zhou, H Li, F Liu, H Fu,

Inorg Chem Commun 2003, 6, 852.

[4] L Fu, R A S Ferreira, N J O Silva, A J Fernandes, P

Rib-eiro-Claro, I S Goncalves, V d Z Bermudez, L D Carlos, J.

Mater Chem 2005, 15, 3117.

[5] G F d Sá, O L Malta, C d M Donegá, R L L A M Simas,

P A Santa-Cruz, E F d Santa Jr., Coord Chem Rev 2000, 196,

165

[6] J A Fernandes, R A S Ferreira, M Pillinger, L D Carlos, J

Jepsen, A Hazell, P Ribeiro-Claro, I S Gonçalves, J Lumin.

2005, 113, 50.

[7] J A Fernandes, S S Braga, M Pillinger, R A S Ferreira, L D

Carlos, A Hazell, P Ribeiro-Claro, I S Gonçalves, Polyhedron

2006, 25, 1471.

[8] P Martín-Ramos, C Coya, Á L Álvarez, M R Silva, C Zaldo,

J A Paixão, P Chamorro-Posada, J Martín-Gil, J Phys Chem.

C 2013, 117, 10020.

[9] J Li, H Li, P Yan, P Chen, G Hou, G Li, Inorg Chem 2012,

51, 5050.

[10] Z Hnatejko, G Dutkiewicz, M Kubicki, S Lis, J Mol Struct.

2013, 1034, 128.

[11] S J Jennifer, P T Muthiah, Inorg Chim Acta 2014, 416, 69.

[12] Z Hnatejko, D Kwiatek, G Dutkiewicz, M Kubicki, R Jastrzab,

S Lis, Polyhedron 2014, 81, 728.

[13] A M Klonkowski, S Lis, M Pietraszkiewicz, Z Hnatejko, K

Czarnobaj, M Elbanowski, Chem Mater 2003, 15, 656.

[14] A M Klonkowski, I Szalkowska, S Lis, Z Hnatejko, Opt

Ma-ter 2008, 30, 1225.

[15] G M Sheldrick, SHELXL-97, Program for the Refinement of

Crystal Structures, University of Göttingen, Germany, 1997.

[16] A L Spek, Acta Crystallogr., Sect D 2009, 65, 148.

[17] Z Hnatejko, S Lis, Z Stryla, P Starynowicz, Polyhedron 2010,

29, 2081.

[18] Z Hnatejko, S Lis, P Starynowicz, Z Stryla, Polyhedron 2011,

30, 880.

[19] D B A Raj, B Francis, M L P Reddy, R R Butorac, V M.

Lynch, A H Cowley, Inorg Chem 2010, 49, 9055.

[20] J E Anthony, D L Eaton, S R Parkin, Org Lett 2002, 4, 15.

[21] H W Roesky, M Andruh, Coord Chem Rev 2003, 236, 91.

[22] C Janiak, J Chem Soc., Dalton Trans 2000, 3885.

[23] D B A Raj, S Biju, M L P Reddy, Inorg Chem 2008, 47,

8091

[24] M H V Werts, R T F Jukes, J W Verhoeven, Phys Chem.

Chem Phys 2002, 4, 1542.

[25] Y.-H Zhou, L Zhou, J Wu, H.-Y Li, Y.-X Zheng, X.-Z You,

H.-J Zhang, Thin Solid Films 2010, 518, 4403.

[26] A Fuchsbauer, O A Troshina, P A Troshin, R Koeppe, R N

Lyubovskaya, N S Sariciftci, Adv Funct Mater 2008, 18, 2808.

Received: March 19, 2015 Published Online: July 17, 2015