Double-armed benzo-15-crown-5 ligands and complexes and single crystal structure determination

Article abstract of DOI:10.1002/hc.21134

This work describes the syntheses and characterizations of double-armed benzo-15-crown-5 containing nitro (1), amine (2), and imine (3-5) groups, and their sodium complexes (1a-5a). Structures of the ligands (1-5) and sodium complexes (1a-5a) were identified via elemental analyses, and infrared, ¹H- nuclear magnetic resonance (NMR), ¹³C-NMR, and mass spectrometry. The metal extractions were examined by using ultravoilet-visible spectrophotometry. Single crystal for 2 was successfully obtained, and its X-ray crystal structure was resolved. The compound 2 crystallizes in triclinic, space group p-1 with a = 9.1420(3), b = 14.9580(4), c = 20.4110(5), and Z = 4.

Full text of DOI:10.1002/hc.21134

Heteroatom Chemistry
Volume 25, Number 1, 2014
Double-Armed Benzo-15-crown-5 Ligands
and Complexes and Single Crystal Structure
Determination
Duygu S¸ ahin,1 Yasemin Su¨zen,2 and Zeliha Hayvalı1
1Department of Chemistry, Ankara University, Faculty of Science, 06100, Ankara, Turkey
2Department of Chemistry, Anadolu University, Faculty of Science, 26470, Eskis¸ehir, Turkey
Received 10 July 2013; revised 9 October 2013
structure, medium polarity, and strong electronega-
ABSTRACT: This work describes the syntheses and
tive effects of heteroatoms on the crown ether ring.
characterizations of double-armed benzo-15-crown-
The crown ethers have been found to be powerful ex-
5 containing nitro (1), amine (2), and imine (3–
tracting agents for the alkali and alkali–earth metals
5) groups, and their sodium complexes (1a–5a).
[5–8]. The cation-binding ability of a crown ether,
Structures of the ligands (1–5) and sodium com-
and its cation selectivity, depend on: the size and
plexes (1a–5a) were identified via elemental analy-
charge density of the cation, the size and flexibility
ses, and infrared, 1H- nuclear magnetic resonance
of the crown ether, the number and the nature of
(NMR), 13C-NMR, and mass spectrometry. The metal
the substituted groups on the macrocyclic ring, the
extractions were examined by using ultravoilet–visible
character and number of the donor atoms, the nu-
spectrophotometry. Single crystal for 2 was success-
cleophilicity of the counterion, and the nature of the
fully obtained, and its X-ray crystal structure was re-
solvent [9]. The introduction of the substituents into
solved. The compound 2 crystallizes in triclinic, space
crown ether molecules affects their spectral, photo-
group p-1 with a = 9.1420(3), b = 14.9580(4), c =
chemical, and complexing properties [10].
ꢀC
20.4110(5), and Z = 4.
2013 Wiley Periodi-
Crown ether compounds having reactive nitro
or amine substituent in the aromatic ring are con-
sidered to be interesting starting materials for the
syntheses of the new crown ether molecules [11,12].
Benzo crown ether Schiff base ligands are important
molecules extensively studied with respect to their
high affinity to interact with alkali and transition
metal ions [13–15]. In general, the oxygen containing
crown ether rings are effective for the complexes of
alkali and alkaline earth metal cations but not tran-
sition metal cations. Conversely, their Schiff base
structures with salicylidene-modified benzocrown
ethers are effective for transition metal ions but
not alkali metal cations [16]. So, salicylidene crown
ether containing Schiff base compounds are known
to bind cations in the crown ether cavity in addi-
tion to the coordination of a transition metal center
through the N2O2 donor atoms [17]. Currently, there
cals, Inc. Heteroatom Chem. 25:43–54, 2014; View
this article online at wileyonlinelibrary.com. DOI
10.1002/hc.21134
INTRODUCTION
Macrocycles are the most important building blocks
in supramolecular chemistry, since their discovery
in 1967 [1–4]. Crown ethers have a central cavity
Correspondence to: Zeliha Hayvalı; e-mail: zhayvali@science
.ankara.edu.tr.
Contract grant sponsor: Scientific and Technical Research
Council of Turkey (TUBITAK).
Contract grant number: TBAG 109T034 and 210T122.
ꢀC
2013 Wiley Periodicals, Inc.
43

44 S¸ahin, Su¨zen, and Hayvalı
FIGURE 1 Syntheses of new crown ethers (1–5).
is a considerable interest in complexes of polyden-
tate macrocyclic ligands, because of the variety of
geometrical forms available and the possible encap-
sulation of the transition metal ion [18].
EXPERIMENTAL
Reagents and Equipments
The starting chemicals, tetraethylene glycol
dichloride [20], benzo-15-crown-5 [1], and 4ꢁ,5ꢁ-
bis(bromomethyl)benzo-15-crown-5 [21] were pre-
pared according to the cited procedure. Compound 1
was prepared by modification of the reported proce-
dure [22,23], and their spectroscopic and analytical
data are discussed below. All solvents and aldehy-
des (salicylaldehyde, 2-hydroxy-3-methoxybenzal-
dehyde, 2-hydroxy-4-methoxybenzaldehyde, and
p-nitrophenol) were purchased from Sigma-Aldrich
Chemical Company (UK) and used without any fur-
ther purification. Melting points were determined
In a previous paper [19], we have prepared
double-armed benzo-15-crown-5 derivatives. In
this paper, 4ꢁ,5ꢁ-bis(bromomethyl)benzo-15-crown-
5 and ortho-nitrophenol were used as starting
materials. But in this study, para-nitrophenol
with 4ꢁ,5ꢁ-bis(bromomethyl)benzo-15-crown-5 were
used as starting materials, and a series of new
p-substituted double-armed crown ether compounds
(1–5) and alkali metal complexes (1a–5a) were
prepared. Synthesized new crown ether Schiff
bases (3–5) were prepared from salicylaldehyde,
2-hydroxy-3-methoxybenzaldehyde, or 2-hydroxy-4-
methoxybenzaldehyde with the amine compound (2)
(Fig. 1). The solid sodium complexes (1a–5a) (Fig. 2)
were obtained by direct reactions between ligands
(1–5) with NaClO4. All solid crown ether ligands
and complexes are described and their infrared (IR),
mass, and 1H- and 13C- nuclear magnetic resonance
(NMR) spectral data are reported. The complexation
abilities of the crown ether compounds (1–5) toward
Na+, K+, Cr3+, Cu2+, Zn2+, and Pb2+ were measured
by the solvent extraction method. The crystal struc-
ture of 2 was determined by X-ray crystallographic
techniques.
1
on a Gallenkamp melting point platform (UK). H
NMR spectra were recorded on a VARIAN Mercury
400 MHz spectrometer (USA). 1H NMR chemical
shifts (δ) are given in ppm downfield from Me4Si,
determined by chloroform (δ = 7.26 ppm). 13C
NMR spectra were recorded on a VARIAN Mercury
100 MHz spectrometer. 13C NMR chemical shifts
(δ) are reported in ppm with the internal CDCl3
at δ 77.0 ppm as the standard. IR spectra were
recorded on a Mattson 1000 Fourier transform
infrared (FT-IR) spectrometer (USA) in KBr disks
and were reported in cm−1 units. Carbon, nitro-
gen, and hydrogen analyses were performed on a
Heteroatom Chemistry DOI 10.1002/hc

Double-Armed Benzo-15-crown-5 Ligands and Complexes and Single Crystal Structure Determination 45
FIGURE 2 Schematic structure of the sodium complexes (1a–5a).
LECO CHNS-932 elemental analyzer (USA). Mass
spectral analyses were performed on a Waters 2695
Alliance MicromassZQ LC/MS spectrometer (USA).
Ultravoilet–visible (UV–vis) spectra were recorded
using a Unicam UV2-100 series spectrophotometer
(UK). Extraction studies were almost the same as
those described in the previous paper [19] (Note:
Picric acid is explosive but also highly shock-, heat-,
and friction sensitive. Do not allow picric acid and
metal picrates to come in contact with skin, eyes, or
respiratory tract at any time).
mmol) was dropwise added and the reaction
mixture was stirred for 1 h. Subsequently, small
portions of 4ꢁ,5ꢁ-bis(bromomethyl)benzo-15-crown-
5 (2.50 g, 5.51 mmol) in 20 mL DMF were added to
the solution. The reaction mixture was refluxed for
24 h, and the consumption of the starting material
was monitored using thin layer chromatography
(silica, eluent; tetrahydrofuran). Then, water was
added to the reaction mixture until the solution
turned cloudy. The light yellow precipitate formed
was isolated and recrystallized from toluene.
[3-({16-[(4-Aminophenoxy)methyl]-2,3,5,6,8,9,
X-ray Data Collection and Structure Refinement
11,12-octahydro-1,4,7,10,13-benzopenta
oxacyclo-
pentadecin-15-yl}methoxy)phenyl]amineo-amin
benzo-15-crown-5 (2). A solution of 1 (1.00 g,
1.76 mmol) dissolved in ethanol (EtOH) (30 mL)
and containing Pd-C (10% 0.10 g) was stirred at 70◦C
and then 12 mL hydrazine monohydrate (75%) was
dropwise added within 1 h to the reaction mixture.
After 4 h of refluxing, the mixture was cooled and
filtered to remove charcoal. The yellow product
was recrystallized from ethanol. Single crystals of
2 suitable for X-ray analysis were obtained by slow
evaporation of EtOH at room temperature.
Crystallographic data were recorded on a Bruker
Kappa APEX II CCD area-detector diffractometer
˚
using Mo Kα radiation (λ = 0.71073 A) at T = 100(2)
K. Absorption corrections by multi-scan [24] were
applied. Structure solutions were performed by di-
rect methods [24], and refined by full matrix least
squares against F2 using all data [25]. All non-H
atoms were refined anisotropically. In compound 2,
the H15a, H15b (for O15) and H16a, H16b (for O16)
atoms were located in a difference synthesis and re-
fined isotropically. The remaining H atoms were po-
˚
sitioned geometrically at distances of 0.93 A (CH),
˚
˚
0.97 A (CH2), and 0.86 A (NH2) from the parent C
and N atoms; a riding model was used during the
refinement process and the Uiso(H) values were con-
strained to be 1.2Ueq (carrier atom) for CH, CH2, and
NH2.
General Procedure for the Synthesis of Schiff Bases
(3–5). The ethanol solution containing 1.96 mmol
of crown amine (2) was dropwise added to
the corresponding aldehydes (salicylaldehyde, 2-
hydroxy-3-methoxybenzaldehyde, or 2-hydroxy-4-
methoxybenzaldehyde) (3.92 mmol) dissolved in
EtOH (20 mL). The solution was stirred under re-
flux for 5–6 h and the reaction mixture was allowed
to stand for 2 h at room temperature. The crude
product was recrystallized from EtOH.
Synthesis of the Compounds
15,16-Bis[(4-nitrophenoxy)methyl]-2,3,5,6,8,9,
11,12-octahydro-1,4,7,10,13-benzopentaoxacyclopen-
tadecine
(1). The
p-nitrophenol
(1.52
g,
11.02 mmol) was dissolved in 20 mL dimethyl-
formamide (DMF). Then, NaOH (5.44 g, 13.60
General Procedure for the Synthesis of Sodium
Complexes (1a–5a). The corresponding crown
Heteroatom Chemistry DOI 10.1002/hc

46 S¸ahin, Su¨zen, and Hayvalı
TABLE 1 Physical Characterization and Analytical Data of Compounds
Elemental analyses (%) found (calc.)
Complex
Formula
C28H30N2O11
C28H34N2O7.H2O
C42H42N2O9
C44H46N2O11
C44H46N2O11
NaC28H30N2O11ClO4
NaC28H34N2O7ClO4
NaC42H42N2O9ClO4
NaC44H46N2O11ClO4
Color
Yield (%) Melting point
C
H
N
1
Light yellow
Yellow
Light yellow
Orange
Yellow
Yellow
Black
41
56
64
58
65
63
61
72
62
40
39
60
47
206◦C
126◦C
144◦C
101◦C
156◦C
236◦C
174◦C
131◦C
125◦C
117◦C
135◦C
136◦C
>250◦C
58.98 (58.94) 5.47 (5.30) 4.44 (4.91)
64.13 (63.62) 6.72 (6.86) 5.33 (5.30)
69.97 (70.18) 5.76 (5.89) 3.92 (3.90)
67.62 (67.85) 5.87 (5.95) 3.51 (3.60)
67.49 (67.85) 5.97 (5.95) 3.55 (3.60)
48.73 (48.53) 4.25 (4.36) 4.12 (4.04)
53.05 (53.13) 5.14 (5.41) 4.47 (4.43)
60.13 (59.97) 5.16 (5.03) 3.20 (3.33)
58.75 (58.64) 5.09 (5.14) 3.18 (3.11)
57.23 (57.49) 5.02 (5.26) 3.15 (3.05)
58.55 (58.28) 5.43 (5,82) 3.33 (3.24)
56.64 (57.09) 5.51 (5.88) 3.02 (3.03)
55.72 (56.00) 5.58 (5.98) 2.97 (2.97)
2
3
4
5
1a
2a
3a
4a
5a
3b
4b
5b
Yellow
Orange
NaC44H46N2O11ClO4.H2O Yellow
NiC42H40N2O9.5H2O
NiC44H44N2O11.5H2O
NiC44H44N2O11.6H2O
Green
Green
Green
TABLE 2 Selected IR Bands (w, weak; m, medium; s, strong)
−
Comp.
ν(C C)
ν(C H)aliph
ν(NO2)
ν(NH2) ν(C N) ν(C
O
C)arom ν(C
O
C)aliph ν(ClO4
)
1
1590(s)
2959; 2850 (m) 1508; 1341 (s)
–
–
–
1301; 1255 (s) 1132; 1090 (s)
1335; 1294 (m) 1114; 1063 (s)
–
–
–
–
–
2
1509; 1470 (s) 2921; 2888 (m)
1506; 1458 (s) 2923; 2871 (w)
1506; 1461 (s) 2937; 2866 (w)
1514; 1459 (s) 2937; 2869 (m)
–
–
–
–
3370 (m)
3
–
–
–
–
1620 (s) 1338; 1285 (s) 1114; 1085 (s)
1616 (s) 1366; 1252 (s) 1113; 1078 (m)
1618 (s) 1375; 1286 (m) 1111; 1046 (m)
4
5
1a
2a
3a
4a
5a
3b
4b
5b
1592 (m)
2919; 2877 (m) 1507; 1338 (m)
–
–
1378; 1257 (s) 1175; 1107 (s) 1081 (s)
1341; 1286 (m) 1034 (s) 1105 (s)
1508; 1457 (s) 2935; 2876 (m)
1507; 1457 (m) 2924; 2872 (m)
1507; 1463 (s) 2934; 2878 (w)
1506; 1456 (s) 2923; 2877 (w)
1505; 1463 (s) 2923; 2868 (m)
1505; 1463 (s) 2924; 2869 (m)
1504; 1455 (s) 2936; 2869 (m)
–
–
–
–
–
–
–
3372 (m)
–
–
–
–
–
–
1619 (s) 1385; 1285 (s) 1114; 1085 (m) 1114 (s)
1615 (m) 1366; 1249 (s) 1198; 1169 (m) 1086 (s)
1619 (s) 1344, 1289 (s) 1097, 1027 (s) 1113 (s)
1610 (s) 1340; 1283 (m) 1112; 1055 (s)
1605 (s) 1340; 1289 (w) 1112; 1079 (s)
1606 (s) 1391; 1288 (w) 1115; 1052 (s)
–
–
–
tween Na+:benzo-15-crown-5 was 1:1 (M:L). All the
crown ether ligands and complexes were stable in
solution and the structures have been verified by ele-
mental analysis, and FT-IR, 1H-, 13C-NMR, and mass
spectra.
ether (1–5) (1.44 mmol) and NaClO4 (0.18 g,
1.44 mmol) were dissolved in EtOH (10 mL) and
refluxed for 2 h. The crude complex was filtered and
recrystallized from ethanol.
The analytical physical data of the amine (2)
compound, crown ether Schiff bases (3–5), and
sodium complexes (1a–5a) are given in Table 1.
RESULTS AND DISCUSSION
Syntheses and Structural Characterization
The starting compound 1 and 2 were succesfully syn-
thesized with the yield of 81% and 56%, respectively.
The single crystal of 2 suitable for X-ray analysis was
obtained by slow evaporation of ethanol.
The direct reaction of one equivalent of (2)
with two equivalent of appropriate aldehyde (sali-
cylaldehyde, 2-hydroxy-3-methoxybenzaldehyde, or
Mass Spectra
The molecular ion peaks and fragments of the
compounds were in good agreement with the sug-
gested structures. In the mass spectra of com-
pound (2), which was obtained by the atmospheric
pressure ionization–electrospray technique, an in-
tensive signal at m/z 509.6 (100%) was observed
and it was assigned to [M H]. The fragments
of significant abundance for compound (2) were
detected at m/z 1021.8 (28.2%), 510.2 (25.7%),
253.6 (7.8%), and 107.1 (10.3%) corresponding
to the [2M], [M], [C14H22O4]+, and [C4H10O3+H]
fragments, respectively. In the electrospray (ES)
2-hydroxy-4-methoxybenzaldehyde)
in ethanol
yielded the corresponding crown ether Schiff base
(3–5).
The sodium complexes (1a–5a) were prepared
by treating a solution of the ligand in EtOH with
NaClO4. The spectroscopic data indicated that the
stoichiometry of the sodium complex formed be-
Heteroatom Chemistry DOI 10.1002/hc

Double-Armed Benzo-15-crown-5 Ligands and Complexes and Single Crystal Structure Determination 47
OH
CH
N
2
–HC
j
j
j
j
A-rH
j
j
j
j
3
H
C
O
O–
2
CH
2
OHC
2
H
N
.
Cmop
Heteroatom Chemistry DOI 10.1002/hc

48 S¸ahin, Su¨zen, and Hayvalı
FIGURE 3 1H-NMR spectra of the crown ether protons (OCH2–CH2O) for free ligands (2 and 3) and sodium complexes (2a
and 3a).
mass spectrum of compound (5), the molecu-
lar peak was not observed, but fragments of sig-
nificant abundance were detected at m/z 668.04
(100%), 646.09 (10.1%), 535.02 (9.2%), 426.82
(10.1%), 334.77 (10.2%), and 269.34 (22.0%) corre-
sponding to the [C37H34N2O10+H], [C35H38N2O10],
[C30H34NO8]+, [C27H23NO4+H], [C21H19NO3+H],
and [C14H20O5+H] fragments, respectively. In the
ES mass spectrum of compound (2a), the dominant
peak at m/z 534.06 (100%) corresponds to the ligand
plus sodium [M + Na]. The fragments of significant
abundance of complex (2a) were observed at m/z
403.07 (10.1%) and 301.78 (15.0%) corresponding
to the [C22H28O7]+ and [C14H22O7]+, respectively.
Heteroatom Chemistry DOI 10.1002/hc

Double-Armed Benzo-15-crown-5 Ligands and Complexes and Single Crystal Structure Determination 49
TABLE 4 Selected 13C-NMR Spectral Data (δ, ppm) (in CDCl3)
ꢁ
ꢁ
ꢁ
Comp.
C1-4
C5
C6
C7
C8
C9-14
C1 = N
C2 -7
-OCH3
–
2
68.74; 69.10;
70.05; 70.61
69.32; 69.57;
70.55; 71.13
148.23
114.15
128.14
67.98
114.75; 115.85;
139.86; 151.35
115.65; 127.99;
141.86; 149.11
–
–
3
4
5
132.77
149.09
141.85
115.47
114.52
113.24
127.99
127.97
128.05
68.12
68.11
68.12
161.74
117.17; 119.01;
119.35; 122.36;
132.01; 160.74
115.66; 118.46;
119.27; 123.60;
148.47; 157.89
101.10; 106.98;
115.44; 128.05;
157.42; 163.70
–
–
69.29; 69.55,
70.54; 71.11
115.44; 122.37;
141.52; 151.30
160.66
163.74
56.22
55.45
69.30; 69.57;
70.55; 71.13
115.63; 122.08;
133.25; 157.42
1a
2a
3a
68.60; 68.86;
69.76; 70.28
68.62; 69.02;
70.17; 70.53
69.38; 69.65;
70.63; 71.58
148.69
148.27
132.52
114.75
113.98
115.49
127.08
127.82
126.68
68.22
67.74
68.14
115.16; 125.81;
141.58; 163.30
114.59; 115.48;
140.01; 151.37
115.61; 128.12;
141.18 ; 148.83
–
–
–
–
–
–
161.58
117.24; 119.17;
119.83; 122.32;
132.19; 160.78
115.62; 118.34;
119.43; 123.59;
148.33; 158.16
101.19; 106.77;
115.16; 128.19;
157.51; 163.78
4a
5a
69.51; 69.83,
70.42; 71.19
148.76
141.74
114.57
114.12
127.83
127.78
68.19
68.16
115.42; 122.46;
141.67; 151.39
160.53
163.61
56.28
55.41
69.38; 69.72;
70.67; 71.19
115.69; 121.90;
133.25; 157.42
served at 1508, 1341 cm−1 (N O asymmetric and
symmetric stretching) and 3370 cm−1 (N H stretch-
ing), respectively. The relatively strong bands at-
tributable to ν(C N) were detected at 1620, 1616,
and 1618 cm−1 for compounds (3–5), respectively.
In the IR spectra of all the new Schiff bases (3–5),
no bands due to ν(NH2) could be observed indicating
the condensation of the two free amine groups. The
IR spectra of the sodium complexes (1a–5a) show
the ligand bands with the appropriate shifts, due to
complex formation. The presence of perchlorate is
indicated by the characteristic broad and very strong
bands at 1081, 1105, 1114, 1086, and 1113 cm−1 for
compound (1a–5a), respectively [26].
FT-IR Spectra
The selected IR data of the compounds are listed
in Table 2. In the IR spectra of the nitro (1) and
amine (2) compounds, both the characteristic in-
ternal ν(NO2) and ν(NH2) absorption bands are ob-
TABLE 5 Main Group and Transition Metal Picrate Extrac-
tions for Compounds (1–5) into CH2Cl2 Phase
Extractibility (%)
Metal Ion
1
2
3
4
5
Na+
K+
25.62
12.01
49.88
47.07
13.20
15.51
45.89
12.11
50.56
51.56
40.30
36.41
51.00
27.59
76.40
61.36
14.79
35.76
45.28
16.60
63.82
47.35
18.36
35.22
48.30
20.21
76.40
55.70
21.94
37.50
Cr3+
Cu2+
Zn2+
Pb2+
1H- and 13C-NMR Spectra
To identify the structures of the nitro (1) and amine
(2) substitue benzo15-crown-5, Schiff bases (3–5)
and alkali metal complexes (1a–5a), the 1H-NMR
Temperature 25 1 °C; aqueous phase (10 mL);[pic−] = 1.17 × 10−4
M, organic phase (10 mL CH2Cl2); [L] = 1 × 10−3 M. [M+] picrate;
1.17 × 10−4 M.
Heteroatom Chemistry DOI 10.1002/hc

50 S¸ahin, Su¨zen, and Hayvalı
FIGURE 4 Percentage extraction (E%) of different metal picrates [M+] picrate; 1.17 × 10−4 M into CH2Cl2 at 25 1◦C.
1
ligands (1–5), four multiplet peaks were seen for the
sodium complexes (1a–5a) in crown ether proton
peaks (OCH2–CH2O) region (Fig. 3). It is well known
[29–31] that the Na+ cations are sufficiently small
to fit into the cavities of benzo-15-crown-5 moieties
specra were recorded in CDCl3. The H-NMR spec-
tral data are summarized in Table 3.
Compound (1–5) spectra indicate that the
molecules are symmetric. In the amine compound
(2), the N H band was detected at δ = 3.45 ppm
as a broad singlet. The absence of the primary aro-
matic amine groups belonging to compound (2) has
also supported the formation of the imine com-
pounds (3–5). The azomethine peaks for compounds
(3–5) were observed as singlets at δ = 8.78, 8.66,
and 8.62 ppm, respectively. The observation of these
singlets confirms the Schiff base reaction between
crown ether amine with apropriate aldehyde. In the
1H-NMR spectrum of the Schiff bases (3–5), the
OH protons give broad singlets at 13.45, 13.85, and
13.97 ppm, respectively. The methoxy (–OCH3) pro-
tons were detected for compounds (3–5) as singlets
in crown ether protons multiplets.
1
of the crown ethers (1–5). In the H-NMR spectra
of the Schiff base sodium complexes (3a–5a), the
OH protons appear as singlets at 13.37, 13.80, and
13.87 ppm, respectively.
The 13C-NMR spectral data are given in Table 4.
The ligands and complexes spectra indicate that the
molecules are symmetric; therefore, in the 13C-NMR
(decoupled) spectra of the ligands (2–5) and com-
plexes (1a–5a), as expected, four crown ether car-
bons were observed between 68.60 and 71.13 ppm. In
addition to that, the spectra were shown the charac-
teristic signals for –OCH3, –CH2, and aromatic ring
carbons.
1
The H-NMR spectra of the sodium complexes
(1a–5a) are approximately the same as in the cor-
responding ligands spectra, but, the H-NMR spec-
Extraction Studies Using UV–vis
Spectrophotometry
1
tra provide compelling evidence for the ligands and
their metal complexes [27]; because different mul-
tiplet peaks shapes were detected in crown ether
protons (OCH2–CH2O) (between 3.5–4.5 ppm) of
the ligands and each sodium complex [2, 28]. Al-
though three multiplet peaks were observed for the
The UV–vis spectrophotometric results, expressed as
percentage of cation extracted (E%), are presented
in Table 5, and shown graphically in Fig. 4. The al-
kali metal cations (Na+ and K+), heavy metal cation
(Pb2+), and transition metal cations (Cu2+, Zn2+, and
Heteroatom Chemistry DOI 10.1002/hc

Double-Armed Benzo-15-crown-5 Ligands and Complexes and Single Crystal Structure Determination 51
◦
˚
TABLE 6 Crystallographic Data, Details of Data Collection,
and Structure Refinement Parameters for Compound 2
TABLE 7 Selected Bond Lengths (A) and Angles ( ) for
Compound 2
2
O1-C3
O1-C7
O2-C8
O2-C9
O3-C10
O3-C11
O4-C12
O4-C13
O5-C4
1.364 (3)
1.429 (3)
1.421 (3)
1.417(3)
1.412 (4)
1.433 (3)
1.414 (3)
1.414 (3)
1.377 (3)
1.436 (3)
1.445 (3)
1.384 (3)
1.442 (3)
1.386 (3)
1.403 (3)
1.389 (3)
1.364 (3)
1.433 (3)
1.418 (3)
1.419 (3)
1.433 (3)
1.434 (3)
1.424 (3)
1.421 (3)
1.374 (3)
1.437 (3)
1.455 (3)
1.382 (3)
1.440 (3)
1.386 (3)
1.404 (3)
1.382 (3)
C3-O1-C7
C8-O2-C9
C10-O3-C11
C12-O4-C13
C4-O5-C14
C15-O6-C16
C22-O7-C23
C31-O8-C35
C36-O9-C37
C38-O10-C39
C40-O11-C41
C42-O12-C32
C43-O13-C44
C50-O14-C51
117.76 (17)
112.3 (2)
115.7 (2)
Empirical formula
Color/shape
Formula weight
T (K)
Radiation used, graphite
monochrome crystal
system
C28H34N2O7 H2O
Yellow/block
528.59
112.3 (2)
117.02 (17)
116.81 (19)
117.32 (18)
117.12 (18)
113.25 (19)
115.0 (2)
112.53 (19)
117.44 (18)
117.34 (19)
115.87 (18)
100 (2)
Triclinic
P-1
Space group
O5-C14
O6-C15
O6-C16
O7-C22
O7-C23
N1-C19
N2-C26
O8-C31
O8-C35
O9-C36
O9-C37
O10-C38
O10-C39
O11-C40
O11-C41
O12-C32
O12-C42
O13-C43
O13-C44
O14-C50
O14-C51
N3-C47
N4-C54
˚
a (A)
9.1420(3)
14.9580(4)
20.4110(5)
72.821(2)
83.960(3)
82.299(3)
2636.19(13)
4
˚
b (A)
˚
c (A)
α (◦)
β (◦)
γ (◦)
3
˚
V (A )
Z
Absorption coefficient (mm−1
)
0.097
1.322
ρcalc (mg mm−3
)
Crystal dimensions (mm)
0.15 × 0.20 × 0.25
θ (Max.) (◦)
28.38
θ (Min.) (◦)
1.43
13208
–12 < h < 12
–19 < k < 19
–27 < l < 27
8242
Reflections measured
Range of h, k, l
Number of reflections with I >
2σ(I)
Corrections applied
Structure solution
Treatment of H atoms
Geometry Calculations &
Difference Mapping
701
1.032
0.0673
0.2217
0.0443
0.839
–0.388
Number of parameters var
Goodness of fit (S)
◦
˚
TABLE 8 Hydrogen-Bond Geometries (A, ) for Compound
2
R = ||Fo| – |Fc|||/|Fo|
Rw
D-H···A
D
H
H···A
D···A
D
H···A
152
Rint
−3
˚
˚
(ꢀ/ρ)max (e A−3
)
)
N2-H2A···O15a
N2-H2B···O16c
N4-H4A···O16d
N4-H4B···O15e
O15-H15A···O3
O15-H15B···O1
O15-H15B···O5
O16-H16A···O8
0.86
0.86
0.86
0.86
2.50
2.23
2.36
2.18
3.288(3)
3.076(4)
3.152(3)
3.025(4)
(ꢀ/ρ) min (e A
169
153
166
168(3)
134(4)
156(4)
136(3)
150(3)
163(4)
142
137
168
136
138
Cr3+) complexation abilities with the crown ethers
(1–5) were studied by solvent extraction of aqueous
metal picrates with CH2Cl2 solution.
0.86(3) 1.93(3) 2.769(3)
0.94(5) 2.34(4) 3.066(3)
0.94(5) 2.10(5) 2.985(3)
0.90(3) 2.34(3) 3.047(3)
Compounds (3–5) contain two types of binding
sites, which may be suitable for complexing alkali
and transition metal cations. The crown ether moi-
eties may complex a small cation, or act coopera-
tively to form an intramolecular sandwich complex
in which a large cation. Alternatively, cationic com-
plexation could occur by the azomethine nitrogen
and phenolic oxygen. Table 5 shows that imine com-
pounds have given higher extractibilities for tran-
sition metals. The new crown ethers generally ex-
hibit high selectivity for the selected metal cations.
As can be seen from Table 5, all of the crown ether
ligands have given relative higher extractibilities to
O16-H16A···O12 0.90(3) 2.26(3) 3.072(3)
O16-H16B···O10 0.87(3) 1.98(3) 2.824(3)
C21-H21···O14a
C25-H25···O8b
C40-H40B···N3a
0.93
0.93
0.93
2.50
2.54
2.57
2.56
2.55
2.53
2.92
3.281(3)
3.284(3)
3.520(3)
3.319(3)
3.303(3)
3.232(3)
3.591(3)
C42- H42A···O15 0.97
C45- H45···O7c
C55- H55···O1d
C17-H17···Cg1e
0.93
0.93
0.93
133
131
Symmetry codes:
ax + 1, y – 1, z.
bx, y – 1, z.
cx – 1, y + 1, z.
d x, y + 1, z.
e2 – x, 1 – y, –z [Cg1 is the centroid of ring A (C1–C6)].
Heteroatom Chemistry DOI 10.1002/hc

52 S¸ahin, Su¨zen, and Hayvalı
FIGURE 5 The molecular structure for 2 with the atom numbering scheme.
FIGURE 6 The intramolecular/intermolecular and weak C H· · ·O hydrogen bonds and C H· · ·π interaction for 2 shown as
dashed lines.
Na+ because of their size fit. The data in Table 5
indicated that compounds (1–5) showed the high-
est extractabilities transition metal cations toward
Cr3+, Cu2+, and Zn2+ when compared with other
cations. Especially, host molecules 3 and 5 display
both high avidity and good selectivity for Cr3+ pi-
crates in solution. The hard and soft acids and bases
principly seem to be important factors in selectivity
for some compounds. Because all crown ether lig-
ands (1–5) contain hard oxygen donor atoms, they
showed preference for Cr3+. Interestingly, crown
compound 2 has given higher binding ability in all
of the metal picrates rather than in compound 1,
which is attributed to the introduction of the sub-
stituent groups. These results indicate that the elec-
tronic effect of the side arm attached to benzo crown
ether alters the cation-binding ability. The extraction
trends of new p-substituted crown compounds (1–
5) and previously worked o-substituted crown com-
pounds [19] were compared. p-Substituted crown
compounds (1–5) showed higher extraction capabil-
ities than o-substituted crown compounds [19] for
the studied metal cations (Na+, K+, Cr3+, Cu2+, Zn2+
,
and Pb2+).
Consequently, the relative size between the
crown ether cavity with the cation and hard and soft
acid-base effects [13, 32–36] are influences for the
complexation ability. Furthermore, the substitution
position effect [36, 37] played an important role in
the formation of complexation with metal ions.
Heteroatom Chemistry DOI 10.1002/hc

Double-Armed Benzo-15-crown-5 Ligands and Complexes and Single Crystal Structure Determination 53
FIGURE 7 Packing diagram for 2.
71.96(8)◦, D/F = 51.27(7)◦, and E/F = 59.79(9)◦. The
Description of the Structures of Compound
2
O
H O hydrogen bonds (Table 8) link the trapped
water molecules to the etheral O atoms of the
macrocyclic ring (Fig. 5). In the crystal structure,
Experimental data for compound 2 are listed in
Table 6; selected bond lengths and angles, and
hydrogen-bond geometries are given in Tables 7
and 8, respectively. In compound 2, the asymmet-
ric unit contains two crystallographically indepen-
dent molecules with similar geometries. The water
molecules are trapped by the 15-membered crown
ether rings. The molecular structures, along with
the atom-numbering scheme and the intramolec-
ular/intermolecular and weak C H· · ·O hydrogen
bonds and C H· · ·π interaction are depicted in
Figs. 5 and 6, respectively. A view of crystal pack-
ing of compound 2 is illustrated in Fig. 7.
intermolecular N
H
O and weak C H· · ·O hydro-
gen bonds (Table 8) link the molecules into a three-
dimensional network, in which they may be effective
in the stabilization of the structure. A C H· · ·π in-
teraction (Table 8) is also observed.
CONCLUSIONS
In conclusion, we have prepared new crown ether
ligands (2–5) and mononuclear sodium complexes
(1a–5a). Molecular structures of the synthesized
1
compounds were identified by FT-IR, H-, and 13C-
Compound 2 consists of two similar benzo-15-
crown-5 rings trapping the water molecules and two
side arms containing the amine groups (Fig. 5). The
relative macrocyclic cavity sizes, estimated as be-
ing twice the mean distance of the donor atoms
from their centroids, are approximately 1.47 and
NMR spectra, and mass and elemental analyses, and
their results showed that all reactions were com-
pleted successfully. The ligand-complexing proper-
ties were studied by solvent extractions of the se-
lected metals (Na+, K+, Cr3+, Cu2+, Zn2+, and Pb2+).
Extraction studies with Cr3+ picrates from aqueous
solution into CH2Cl2 have shown that compounds
3 and 5 are better phase-transfer agents and also
more selective than other compounds. The solid-
state structures of compound (2) were determined
by single-crystal X-ray crystallography.
˚
˚
1.48 A, using the modified covalent radius (0.76 A)
3
of the Osp atoms, as demonstrated in the literature
[38–40]. The polyhedral volume of the 15-membered
crown rings is calculated as 25.30(5) and 25.37 (8) A.
˚
The ꢁCO torsion angles (C16-O6-C15-C6), (C23-O7-
C22-C1), (C44-O13-C43-C34), and (C51-O14-C50-
C29) are –161.01(19)◦, –166.2(2)◦, 158.78(19)◦, and
170.95(19)◦, respectively. The rings A (C1-C6), B
(C16-C21), C (C23-C28), and D (C29-C34), E (C44-
C49), and F (C51-C56) are, of course planar, and they
are oriented at dihedral angles of A/B = 72.64(8)◦,
A/C = 58.44(7)◦, and B/C = 50.98(8)◦ and D/E =
Supplementary Data
CCDC 909657 contains the supplementary crystallo-
graphic data for compound 2. These data can be
obtained free of charge via http://www.ccdc.cam.
Heteroatom Chemistry DOI 10.1002/hc

54 S¸ahin, Su¨zen, and Hayvalı
[18] Shakir, M.; Varkey, S. P.; Nasmon, O. S. M. Polyhe-
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[19] S¸ ahin, D.; Hayvalı, Z. J. Incl Phenom Macrocycl
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[20] Calverly, M. J.; Dale, J. Acta Chem Scand 1982, 36B,
241–247.
ac.uk/conts/retrieving.html, or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK; fax (+44) 1223-336-033; or e-
mail: deposit@ccdc.cam.ac.uk.
[21] Winkler, B.; Mau, A. W.-H.; Dai, L. Phys Chem Chem
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ACKNOWLEDGMENTS
[22] Han, J.-R.; Zhen, X.-L.; Tian, X.; Liu, S.-X. Chinese J
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[24] SADABS Bruker, AXS Bruker, Inc. Madison, Wiscon-
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Authors would like to thank Anadolu University and
Medicinal Plants and Medicine Research Center of
Anadolu University, Eskis¸ehir, Turkey, for allowing
us to use the X-Ray facility.
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Heteroatom Chemistry DOI 10.1002/hc