Synthesis and characterization of novel urea and thiourea substitute cyclotriphosphazene compounds as naked-eye sensors for F- and CN- anions

Article abstract of DOI:10.3906/kim-1502-59

Novel hexakisurea and thiourea cyclotriphosphazene compounds (3-7) were synthesized. The structure of all compounds was identified using FT-IR ¹ H, ¹³ C, and ³¹P NMR spectroscopy; MALDI-TOF MS; and elemental analysis. The

Full text of DOI:10.3906/kim-1502-59

Turk J Chem
2015) 39: 777 – 788
Turkish Journal of Chemistry
(
http://journals.tubitak.gov.tr/chem/
¨
˙
⃝
c TUBITAK
Research Article
doi:10.3906/kim-1502-59
Synthesis and characterization of novel urea and thiourea substitute
−
−
cyclotriphosphazene compounds as naked-eye sensors for F and CN anions
1,∗
2
3
¨
¨
¨
Hava OZAY , Mehmet YILDIRIM , Ozg u¨ r OZAY
1
Department of Chemistry, Inorganic Chemistry Laboratory, Faculty of Science and Arts,
C¸ anakkale Onsekiz Mart University, C¸ anakkale, Turkey
2
Department of Materials Science and Engineering, Faculty of Engineering,
C¸ anakkale Onsekiz Mart University, C¸ anakkale, Turkey
Department of Chemistry and Chemical Processing Technologies, Lapseki Vocational School,
C¸ anakkale Onsekiz Mart University, Lapseki, C¸ anakkale, Turkey
3
Received: 10.02.2015
•
Accepted/Published Online: 25.05.2015
•
Printed: 28.08.2015
Abstract: Novel hexakisurea and thiourea cyclotriphosphazene compounds (3–7) were synthesized. The structure
1
13
31
of all compounds was identified using FT-IR H, C, and P NMR spectroscopy; MALDI-TOF MS; and elemental
analysis. The optical sensor properties for anions of 3–7 were investigated using UV-Vis spectroscopy. It was determined
−
−
that compounds 6 and 7 are spectrophotometric and naked eye sensors for F and CN anions, respectively. Sensor
properties of these compounds for anions were investigated using UV-Vis spectroscopy. The stoichiometry of host–guest
complexes was found to be 1:6.
Key words: Cyclotriphosphazene, urea, thiourea, naked-eye sensor
1
. Introduction
Phosphazenes that contain –P=N(X2)– units in their skeleton create a large class of inorganic–organic hybrid
compounds.1,2 Phosphazene compounds have been a focus of interest for many researchers due to their ap-
plications such as forming a core for dendrimeric molecules,3,4 multicentered ion sensors,5,6 metal carbonyl
derivative,7 flame retardant agent,8,9 biodegradable materials,
10−12
and liquid crystalline materials.13
Urea and thiourea derivatives are very interesting compounds due to their biological activities. Recently,
numerous urea and thiourea compounds have been reported in the literature as antitumor agents,14,15 glucoki-
nase activators,16 pruvate dehydrogenase inhibitors,17 and corrosion inhibitors.18 At the same time, urea and
thiourea compounds are good hydrogen binding donors. Thanks to these features, numerous urea and thiourea
derivatives have been used as naked-eye anion sensors.1
9−29
Many of these sensor compounds are monopodal
or dipodal compounds. Khandelwal et al. have reported tetrapodal urea derivatives as colorimetric sensors for
fluoride and pyrophosphate anions.30
In the present study, we synthesized novel hexapodal urea and thiourea compounds with cyclotriphos-
phazene cores. Firstly, hexakis(4-aminophenoxy)cyclotriphosphazene 2 was synthesized according to the liter-
ature procedure.31,32 Afterwards, four urea (3–6) and one thiourea derivative (7) were synthesized from the
reaction of 2 with isocyanate and isothiocyanate compounds. Structures of all synthesized compounds were
∗
Correspondence: havaozay@comu.edu.tr
7
77

¨
OZAY et al./Turk J Chem
characterized using spectral methods such as FT-IR, NMR, and MALDI TOF-MS. Then the interaction of all
compounds with anions in solvent media was investigated. It was determined that 4-nitrophenylurea derivative
6
and 4-nitrophenylthiourea derivative 7 act as naked-eye sensors for fluoride and cyanide anions, respectively.
Detailed sensor studies were performed for these two compounds.
2
2
. Results and discussion
.1. Synthesis and structural characterization of all compounds
It is well known that hexachlorocyclotriphosphazene can easily react with nucleophiles such as amines, alcohols,
3−35
and phenols.3
Therefore, firstly the reaction of hexachlorocyclotriphosphazene with 4-acetamidophenol in
the presence of K2 CO3 as base was carried out in acetone. Compound 1 was obtained from this reaction with
good yield (83%). Acetamide groups of compound 1 were converted to amine groups by hydrolysis with aqueous
NaOH.31,32 Hexapodal urea and thiourea compounds 3–7 were synthesized from the reaction of hexaamine
substitute cyclotriphosphazene compound 2 and different isocyanate and isothiocyanate compounds under mild
reaction conditions with good yield (Scheme 1).
The structures of all compounds were identified using FT-IR, 1 H NMR, 13 C NMR, 31 P NMR, and
MALDI TOF-MS spectroscopy, and elemental analysis data. All results are given in the experimental section.
In the FT-IR spectrum of compound 1 stretching vibrations of C=O and –P=N– were observed at 1658 and
−
1
1
162 cm , respectively. The peaks related to N–H and –P=N– of compound 2 were observed at 3340–3204
−1
and 1158 cm
in the FT-IR spectrum. Urea and thiourea compounds 3–7 produced peaks related to –P=N–
stretching vibration at 1162, 1177, 1159, 1162, and 1159 cm , respectively. As seen in the 1 H NMR spectrum,
NH protons of urea groups in the structure of compound 3 resonated at δ = 8.75 and 8.70 ppm. The aromatic
protons of 3 resonate in the δ = 6.86–7.69 region. The signal related to methylene protons of the fluorene
group was observed at δ = 3.74 ppm as a singlet. Compound 3 has 17 signals in the 13 C NMR spectrum.
The carbonyl carbon was observed at δ = 152.99 ppm. The chemical shifts for aromatic carbons were at δ
−
1
=
144.31, 142.95, 141.56, 139.19, 137.37, 135.54, 127.06, 126.15, 125.31, 121.35, 120.54, 119.85, 119.55, 117.61,
and 115.49 ppm. The signal of fluorene –CH2 – was observed at δ = 36.87 ppm. The signals related to NH
protons of 4 were observed at δ = 8.59 and 8.45 ppm in the 1 H NMR spectrum. Aromatic protons resonate
in the region of δ = 6.70–7.33 ppm. The signal of methylene protons in the structure of 4 was observed at δ
=
5.92 ppm as a singlet. According to the 13 C NMR spectrum of 4, the compound has 10 signals. The signal
for carbonyl carbon was observed at δ = 153.06 ppm. The signals related to aromatic carbons were observed
at δ = 147.59, 142.47, 137.34, 134.39, 122.23, 110.72, 111.54, 108.44, and 101.48 ppm. The methylene carbon
resonated at δ = 101.22 ppm. The signal related to M+ + H+ for the compound in the MS spectrum was
observed at 1763.2150. All spectral results are confirmed for the purposed structure.
The aromatic and aliphatic NH protons of urea groups of compound 5 were observed at δ = 8.58 ppm
as a singlet signal and δ = 6.55 ppm as a triplet signal, respectively. The signals related to aromatic protons
were observed at δ = 7.57 ppm as a multiplet; δ = 7.32, 6.78, and 6.27 ppm as doublets; and δ = 6.39 ppm as
a multiplet. The chemical shift for aliphatic –CH2 – protons was observed at δ = 4.30 ppm as a doublet signal.
Compound 5 has 10 signals related to carbonyl carbon, and 8 aromatic and 1 aliphatic carbons in the 13
C
NMR spectrum. The signal related to the protonated molecular ion of 5 was observed at 1523.9500 in the MS
spectrum. All the spectral results were consistent with the predicted structure of 5. NH protons of the nitro
substituted compound 6 were observed at δ = 9.32 and 8.87 ppm. The signals of aromatic protons in 6 were
observed at δ = 7.97, 7.57, 7.38, and 6.83 ppm as doublet signals. The compound has 10 signals in 13 C NMR
778

¨
OZAY et al./Turk J Chem
H COCHN
3
NHCOCH3
H COCHN
3
O O
Cl Cl
NHCOCH3
P
P
NHCOCH3
K CO3
2
N
N
N
N
O
Cl
+
O
Cl
P
P
P
P
Acetone
N
N
O
O
Cl
Cl
OH
H COCHN
3
NHCOCH3
1
NaOH/H O
2
CH OH
3
X
X
NH
HN
R NH
HN R
H N
2
NH2
X
H
N
O O
X
H
N
R NH
H N
2
O O
P
N
N
P
O
HN R
R N C X
NH2
O
N
N
O
P
P
P
O
N
O
O
P
N
O
O
R NH
X
N
H
X
HN
H N
2
HN R
2
NH2
3
4
5
: X=O R=
: X=O R=
: X=O R=
6: X=O R=
7: X=S R=
NO2
NO2
O
O
O
Scheme 1. Synthetic route for compounds.
spectrum. The chemical shift related to carbonyl carbon was observed at δ = 152.24 ppm. The molecular ion
peak of 6 was observed at 1768.3280 in the MS spectrum. All the spectral results were consistent with the
predicted structure of 6. NH protons of thiourea derivative 7 were observed at δ = 10.39 and 10.23 ppm. The
aromatic protons of the compound resonate at δ = 8.16, 7.85, 7.54, and 6.99 ppm as doublet signals. The signal
related to the C=S group in 7 was observed at δ = 186.55 ppm in the 13 C NMR spectrum. The chemical shifts
of aromatic carbons were observed at δ = 153.85, 146.14, 143.20, 137.55, 128.51, 125.30, 123.12, and 120.68
ppm. The signal related to M+ at 1865.3250 in the MS spectra confirmed the predicted structure. A single
peak related to three identical phosphorus atoms was observed in the 31 P NMR spectra of all compounds. The
identical phosphorus atoms of compound 3–7 resonated at δ = 9.65, 9.34, 9.42, 9.69, and 9.67 ppm.
7
79

¨
OZAY et al./Turk J Chem
2
.2. The sensor applications of compounds 3–7
The sensor features of 3–7 were investigated with a UV-Vis spectrophotometer in DMSO and DMSO:H2 O
−
−
−
−
4
−
−
−
−
−
solvent mixture in the presence of anions such as AcO , F , NO , HSO , SCN , CN , Br , Cl , I ,
2
−
−
H2 PO , and NO . It was determined that receptors 3–5 did not exhibit naked-eye and spectrophotometric
4
3
sensor properties for these anions (data not shown). However, receptors 6 and 7 exhibited selective sensor
−
−
behavior for F and CN anions (Figures 1a and 1b).
Figure 1. Solution color of 6 and 7 exposed to various types of anions under sunlight. (a) 6 (50 µM) and anion (500
2
µM) in DMSO, (b) 7 (25 µM) and anion (250 µM) in DMSO:H O (9:1).
Urea derivative compounds contain a relatively acidic NH group as center that interacts with the anions.
−
These compounds interact with the F anion, which is a relatively strong base. This interaction may result
in deprotonation of acidic amid NH groups.25 However, a negligible change as a result of interaction of urea
compounds with CN anion has been reported in the literature.21,22
−
Urea derivative 6 showed an absorption maximum at λ = 390 nm in DMSO. After the addition of
−
−
−
−
−
−
−
−
−
−
−
AcO , F , NO , HSO , SCN , CN , Br , Cl , I , H2 PO , and NO anions, a remarkable increase in
2
4
4
3
absorption was observed at λ = 478 nm only in the presence of fluoride anions (Figures 2a and 2b). Similarly to
−
reports in the literature, negligible change was observed in the presence of CN anion in the UV-Vis spectrum
−
−
−
−
−
and in the color of solution of 6. No changes were observed in the presence of Br , Cl , I , NO , HSO ,
2
4
−
−
−
−
AcO , H2 PO , NO , and SCN anions. It can be said that compound 6 does not enter into any remarkable
4
3
interaction with these anions.21,22 Additionally, it was observed that the absorption at λ = 478 nm increased
with increasing concentration of fluoride anions (Figures 2c and 2d). A new absorption maximum at λ = 478
nm indicated intramolecular charge transfer (ICT) between anion–urea and the electron deficient p-nitrophenyl
groups.25,36
−
Stoichiometry for the host–guest complex between compound 6 and F anions was determined as 1:6
from the Job’s plot. The total concentration was kept constant at 500 µM (Figure 3a). As shown in Figure
8
3
b, the apparent stability constant Kas was calculated as 1.77 × 10 from UV-Vis titration data (y = 2.5068x
2
+
8.2469, R = 0.9816) using the Benesi–Hildebrand equation. The Kas value of 6 is greater than the values
obtained for a large number of similar mono-, di-, and tripodal compounds. According to the literature, higher
780

¨
OZAY et al./Turk J Chem
binding values for host–guest interactions are obtained because the interaction increases with the number of
centers interacting with the anions.2
6,28−30
1
1
0
0
.5 (a)
0.6
.5
0.4
.3
0.2
.1
(b)
0
.0
.5
.0
0
0
0
3
75
450
525
600
1
2
3
4
5
6
7
8
9
10 11 12
Wavelength (nm)
An!on
2
1
1
0
0
.0
.5
.0
.5
.0
1.6
1.2
0.8
0.4
y = 0.002x - 0.2814
R2 = 0.9822
(c)
(d)
1
000 µM
–
0 µM F
0
4
00
450
500
550
600
0
200
400
-
600
800
Wavelength (nm)
[F ] (µM)
Figure 2. (a) Absorption spectra, (b) Absorption intensity of 6 (50 µM) in the presence of different anions (500 µM) in
−
DMSO, (c) Absorption spectra of 6 (50 µM) upon addition of different amounts of F in DMSO, (d) Plot of absorbance
−
−
−
−
−
−
−
−
for 6 (50 µM) and F (100–800 µM): 1: 6 (Blank), 2: F , 3: Cl , 4: Br , 5: I , 6: CN , 7: NO2 , 8: AcO , 9:
−
−
−
−
PO , 12: HSO4 .
NO , 10: SCN , 11: H
2
3
4
1
0
1
2
0
0
0
.3
.2
.1
(b)
(
a)
-
-
0
-3
0
0.2
0.4
0.6
0.8
1
-4.5
-4
-3.5
-3
–
log[F ]
–
F]/[F ]+[6]
[
−
Figure 3. (a) Job’s plot of absorbance for the determination of binding stoichiometry of 6–F complex, (b) Determi-
−
nation of the apparent stability constant (Kas) for 6–F
.
−
CN anion is a toxic species for living organisms. Therefore, the determination of this anion in aqueous
media is very important. NH groups of thiourea derivatives have higher acidities than urea NH groups because
sulfur atoms form weaker intermolecular hydrogen bonds than oxygen atoms.25 This feature makes the thiourea
−
compounds active against CN anions. For this reason, thiourea compounds with naked-eye sensor features
for both F and CN anions have been reported in the literature.21,22,36,37 Thiourea derivative 7 showed a
−
−
−
remarkable response only to the CN anion in DMSO:H2 O (9:1). The color of the solution of 7 turned from
−
colorless to yellow in the presence of CN anions (Figure 1b). As shown in UV-Vis spectra of compound 7,
7
81

¨
OZAY et al./Turk J Chem
a new absorption maximum related to the intramolecular charge transfer (ICT) formed at λ = 472 nm only
−
in the presence of CN anions. Negligible changes were observed in the UV-Vis spectra and solution color of
−
−
−
7
in the presence of F , AcO , and H2 PO in DMSO:H2 O (9:1) solvent mixture. The reason for the weak
4
−
signal observation for the F anion, which is a strong base, is the decrease in hydrogen binding ability of the
−
F
anion with thiourea NH protons in the presence of water.27 Absorption intensity at λ = 472 nm increased
−
during the titration with CN anions (Figures 4a–4d).
1
.2
1
0.5
(a)
(b)
0.4
0.3
0.2
0.1
0
0
0
0
0
.8
.6
.4
.2
0
2
60
320
380
440
500
560
1
2
3
4
5
6
7
8
9
10 11 12
Wavelength (nm)
An!on
1.2
(c)
1
.2
(d)
1
1
.8
.6
1
000 µM
µM CN--
580
0
0
0
0
.8
.6
.4
.2
0
0
0
0
0.4
0.2
0
400
460
520
0
200
400
-
600
800
Wavelength (nm)
[CN ] (µM)
Figure 4. (a) Absorption spectra, (b) Absorption intensity of 7 (25 µM) in the presence of different anions (250 µM)
−
in DMSO:H
2
O (9:1), (c) Absorption spectra of 7 (25 µM) upon addition of different amounts of CN in DMSO:H
2
O,
−
−
−
−
−
−
(
d) Plot of absorbance for 7 (25 µM) and CN (50–700 µM): 1: 7 (Blank), 2: F , 3: Cl , 4: Br , 5: I , 6: CN
,
−
−
−
−
−
−
7
: NO2 , 8: AcO , 9: NO3 , 10: SCN , 11: H
2
PO , 12: HSO4 .
4
−
Stoichiometry for the 7–CN complex ion was determined by the Job’s plot. The absorption reaches a
−
maximum at approximately 0.85 molar fraction of CN , and it was determined that compound 7 formed a 1:6
−
−
complex with a CN anion (Figure 5a). The binding constant for 7–CN complex was calculated as Kas =
.25 × 10 using the Benesi–Hildebrand equation (y = 2.444x + 8.353, R2 = 0.9533) (Figure 5b).
8
2
The interaction mechanisms of compound 6 and 7 with F and CN anions were investigated using 1
−
−
H
NMR titration in DMSO-d6 . NH protons observed at δ = 9.32 and 8.87 of compound 6 disappeared in the
presence of tetrabutylammonium fluoride (Figure 6a). A similar observation of deprotonation of urea protons
−
21,22,26−29
or strong hydrogen binding with F anions has been reported in the literature.
Similar effects were observed for compound 7. As shown in Figure 6b, addition of tetrabutylammonium
cyanide to the solution of compound 7 resulted in disappearance of signals at δ = 10.39 and 10.23 ppm of NH
protons due to the deprotonation process. As a result of all these spectral findings, a binding model for 6 (or
7
)–anion was proposed with the structure in Scheme 2 in accordance with the literature.25,27
782

¨
OZAY et al./Turk J Chem
1
.6
(b)
2
.5
1
(a)
0.8
0
1
0
-
-
-
-
0.8
1.6
2.4
3.2
.5
0
0
0.2
0.4
0.6
0.8
1
-4.5
-4.25
-4
-3.75
-3.5
-3.25
-3
–
log[CN ]
–
CN]/[CN ]+[7]
[
−
Figure 5. (a) Job’s plot of absorbance for the determination of binding stoichiometry of 7–CN
complex,
−
(
b) determination of the apparent stability constant (Kas) for 7–CN
.
(a)
-
6
+ F
6
(b)
-
7
+ CN
7
1
Figure 6. H NMR spectra of (a) 6 in the presence of 6 equivalents of TBAF, (b) 7 in the presence of 6 equivalents
◦
of TBACN in DMSO-d
6
at 25 C.
Consequently, we synthesized novel fully substituted cyclotriphosphazene compounds (3–7) with urea
and thiourea functional groups. Thus, a new type of class of compounds was added to the literature. Moreover,
we used compounds 6 and 7 as receptors for detection of anions. Compound 6 showed good selectivity for
−
F
anions in the presence of other anions in DMSO as solvent. Compound 7 showed good selectivity for
7
83

¨
OZAY et al./Turk J Chem
−
CN anions in the presence of other anions in DMSO:H2 O solvent mixture. Deprotonation or strong hydrogen
bonding of compounds in the presence of anions in DMSO was confirmed by 1 H NMR titration.
Scheme 2. The proposed sensing mechanism for host–guest complex.
3
3
. Experimental
.1. Materials and equipment
Hexachlorocyclotriphosphazene was purified by recrystallization from hexane. THF was dried by sodium/
benzophenone system under argon atmosphere. All reagents for synthesis were purchased from a chemical
company (Sigma-Aldrich) and were used as received without purification. All reactions were monitored by
using TLC (Kieselgel 60F254 silica gel precoated plates). In the sensor applications tetrabutylammonium salts
−
−
−
−
−
−
−
−
−
−
−
of AcO , F , NO , HSO , SCN , CN , Br , Cl , I , H2 PO , and NO were used as anion sources.
2
4
4
3
FT-IR spectra of compounds were recorded using a PerkinElmer FT-IR instrument with ATR apparatus with 4
−
1
−1
cm
resolution between 4000 and 650 cm . All NMR spectra were recorded using Varian Unity INOVA (500
MHz) instrument. Tetramethylsilane as interval reference was used in H and 13 C NMR measurements and 85%
1
H3 PO4 as interval reference was used in 31 P NMR measurements. All NMR measurements were carried out
using DMSO-d6 as solvent. Mass spectra of compounds were recorded on Bruker Microflex LT MALDI-TOF MS
spectrometers. All UV-Vis absorption spectra were recorded using a PG Instruments T80+ spectrophotometer
in the sensor studies. The melting points of all compounds were measured on an Electrothermal IA 9100 model
melting point apparatus using a capillary tube.
3
.2. Synthesis of hexakis(4-acetamidophenoxy)cyclotriphosphazene (1)
Compound 1 was synthesized in a similar way to the literature procedure.31,32 A solution of hexachloro-
cyclotriphosphazene (3.48 g, 10.00 mmol) in dry acetone (50 mL) was added dropwise to a solution of 4-
acetamidophenol (10.88 g, 72.00 mmol) and anhydrous K2 CO3 (13.94 g, 0.10 mol) in dry acetone (250 mL).
The reaction mixture was refluxed for 72 h under argon atmosphere. At the end of this time, salts were filtered
and the solvent was removed by rotary evaporator under reduced pressure. The crude solid was washed with
deionized water (200 mL) to remove salts. Afterwards, the solid product was washed with ethanol (2 × 50 mL)
and hexane (2 × 25 mL), consecutively. The obtained white solid was dried. Yield 8.57 g (83%). mp 254–255
◦
C. FTIR-ATR (νmax , cm ): 3284 (N–H), 1658 (C=O), 1501 (C=C), 1162 (P=N), 953 (P–O–C). 1 H NMR
−1
◦
(
500 MHz, DMSO-d6 , 25 C, ppm): δ 9.94 (s, 6H, NH), 7.42 (d, 12H, J = 8.1 Hz, ArH), 6.79 (d, 12H, J =
1
3
◦
C NMR (125 MHz, DMSO-d6 , 25 C, ppm): δ 168.69 (C=O), 145.53,
8
.1 Hz, ArH), 2.02 (s, 18H, CH3).
36.87, 121.01, 120.58, 24.33. 31 P NMR (202 MHz, DMSO-d6 , 25 C, ppm): δ 9.19. MALDI MS m/z: Calcd
◦
1
for C48 H48 N9 O12 P3 + H+ 1036.1761 Found: 1036.2020.
784

¨
OZAY et al./Turk J Chem
3
.3. Synthesis of hexakis(4-aminophenoxy)cyclotriphosphazene (2)
Compound 2 was synthesized according to the literature procedure.31,32 To a solution of compound 1 (8.00 g,
.22 mmol) in methanol (300 mL) was added a solution of NaOH (37.00 g, 0.93 mol) in water (50 mL). The
7
reaction mixture was refluxed for 24 h under argon atmosphere. During this time, a white solid formed in the
reaction mixture. At the end of the reaction time, the solid formed was separated by filtration. The pale yellow
solid was washed with water until neutral and was dried at room temperature. Yield 3.98 g (66.82%). mp
◦ −1
88–189 C. FTIR-ATR (νmax , cm ): 3340, 3204 (N–H), 1621, 1503 (C=C), 1158 (P=N), 961 (P–O–C).
1
3
.4. Synthesis of hexakis(1-oxyphenyl-3-fluorene urea)cyclotriphosphazene (3)
A solution of compound 2 (0.39 g, 0.50 mmol) in dry THF (50 mL) was added dropwise to a solution of 9H-
fluoren-2-yl-isocyanate (0.73 g, 3.25 mmol) in dry THF (50 mL). The reaction mixture was stirred at ambient
temperature for 24 h under argon atmosphere. At the end of this time, the white solid matter formed was
◦
−1
filtered, washed with THF (25 mL), and dried. Yield 0.95 g (94%). mp 273–274 C. FTIR-ATR (νmax , cm ):
3
289 (N–H), 3043 (Ar–H), 1648 (C=O), 1554, 1501 (Aromatic C=C), 1162 (P=N), 963 (P–O–C). 1 H NMR
◦
(
500 MHz, DMSO-d6 , 25 C, ppm): δ 8.75 (s, 6H, ArNH), 8.70 (s, 6H, ArNH), 7.69 (s, 6H), 7.63 (t, 12H,
J = 8.8 Hz, ArH), 7.41 (m, 24H), 7.26 (t, 6H, J = 7.4 Hz, ArH), 7.17 (t, 6H, J = 7.5 Hz, ArH), 6.86 (d, 12H,
1
3
◦
J = 8.8 Hz, ArH) 3.74 (s, 12H, –CH2 – Fluorene).
C NMR (125 MHz, DMSO-d6 , 25 C, ppm): δ 152.99
(
C=O), 144.31, 142.95, 141.56, 139.19, 137.37, 135.54, 127.06, 126.15, 125.31, 121.35, 120.54, 119.85, 119.55,
3
1
◦
P NMR (202 MHz, DMSO-d6 , 25 C, ppm): δ 9.65. MALDI MS m/z: Calcd for
117.61, 115.49, 36.87.
+
+
C120 H90 N15 O12 P3 – (6H ) + (Na ), 2044.1170. Found: 2044.1130. Anal. Calcd. for C120 H90 N15 O12 P3 :
C, 71.10; H, 4.48; N, 10.37%. Found: C, 71.04; H, 4.46; N, 10.32%.
3
.5. Synthesis of hexakis(1-oxyphenyl-3-((3,4-methylenedioxy)phenyl) urea)cyclotriphosphazene
4)
(
To a solution of 3,4-(methylenedioxy)phenyl isocyanate (0.68 g, 4.15 mmol) in dry THF (50 mL) was added
dropwise a solution of compound 2 (0.50 g, 0.64 mmol). The reaction mixture was stirred at ambient temperature
for 24 h under argon atmosphere. Then the white solid formed in the reaction mixture was filtered and washed
◦
with THF (25 mL). Compound 4 was obtained as a white solid. Yield 1.05 g (93%). mp 264–265 C. FTIR-
ATR (νmax , cm 1): 3315 (N–H), 1658 (C=O), 1558 (Aromatic C=C), 1177 (P=N), 948 (P–O–C). 1 H NMR
−
◦
(
500 MHz, DMSO-d6 , 25 C, ppm): δ 8.59 (s, 6H, ArNH), 8.45 (s, 6H, ArNH), 7.33 (d, 12H, J = 8.8, ArH),
1
3
7.15 (s, 6H, ArH), 6.81(d, 12H, J = 8.8 Hz, ArH), 6.76–6.70 (m, 12H, ArH), 5.92 (s, 12H, CH2).
C NMR
◦
(
125 MHz, DMSO-d6 , 25 C, ppm): δ 153.06 (C=O), 147.59, 142.47, 137.34, 134.39, 122.23, 110.72, 111.54,
08.44, 101.48, 101.22 (Ar–C). 31 P NMR (202 MHz, DMSO-d6 , 25 C, ppm): δ 9.34. MALDI MS m/z: Calcd
◦
1
+
for C84 H66 N15 O24 P3 + H , 1763.4310. Found: 1763.2150. Anal. Calcd. for C84 H66 N15 O24 P3 : C, 57.24;
H, 3.77; N, 11.92%. Found: C, 57.19; H, 3.76; N, 11.89%.
3
.6. Synthesis of hexakis(1-oxyphenyl-3-furfuryl urea)cyclotriphosphazene (5)
A solution of compound 2 (0.39 g, 0.50 mmol) in dry THF (40 mL) was added dropwise to a solution of furfuryl
isocyanate (0.40 g, 3.25 mmol) in dry THF (10 mL). The reaction mixture was stirred at ambient temperature
for 24 h under argon atmosphere, then filtered, and a white solid crude product was obtained. The crude
7
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OZAY et al./Turk J Chem
◦
product was washed with THF (25 mL) and dried at ambient temperature. Yield 0.64 g (92%). mp 230–231 C.
−
FTIR-ATR (νmax , cm 1): 3297 (N–H), 1636 (C=O), 1563, 1503 (Aromatic C=C), 1177–1159 (P=N), 952
P–O–C). 1 H NMR (500 MHz, DMSO-d6 , 25 C, ppm): δ 8.58 (s, 6H, ArNH), 7.57 (m, 6H), 7.32 (d, 12H, J
◦
(
=
9.1 Hz, ArH), 6.78 (d, 12H, J = 8.9 Hz, ArH), 6.55 (t, 6H, J = 5.8 Hz, NH-Aliphatic), 6.39 (m, 6H), 6.27
(
d, 6H, J = 3.0 Hz, ArH), 4.30 (d, 12H, J = 5.8 Hz, –CH2). 13 C NMR (125 MHz, DMSO-d6 , 25 C, ppm):
◦
3
1
δ 155.44 (C=O), 153.59, 144.63, 142.52, 137.86, 121.17, 119.24, 110.89, 106.93 (Ar–C), 36.64 (–CH2).
P
◦
+
NMR (202 MHz, DMSO-d6 , 25 C, ppm): δ 9.42. MALDI MS m/z: Calcd for C72 H66 N15 O18 P3 + (H ),
1523.3100. Found: 1523.950. Anal. Calcd. for C72 H66 N15 O18 P3 : C, 56.81; H, 4.37; N, 13.80%. Found: C,
56.77; H, 4.35; N, 13.76%.
3
.7. Synthesis of hexakis(1-oxyphenyl-3-(4-nitrophenyl) urea)cyclotriphosphazene (6)
A solution of compound 2 (0.50 g, 0.64 mmol) in dry THF (50 mL) was added dropwise to a solution of 4-
nitrophenyl isocyanate (0.69 g, 4.15 mmol) in dry THF (50 mL). The reaction mixture was stirred at ambient
temperature for 24 h under argon atmosphere and then the yellow solid formed was separated by filtration. The
yellow crude product was washed with THF (25 mL) and dried at ambient temperature. Yield 1.07 g (95%).
◦
−1
mp 290–291 C. FTIR-ATR (νmax , cm ): 3352 (N–H), 3080 (Ar–H), 1679 (C=O), 1558 (Aromatic C=C),
◦
1
6
1
1
2
491 and 1329 (–NO2), 1162 (P=N), 948 (P–O–C). 1 H NMR (500 MHz, DMSO-d6 , 25 C, ppm): δ 9.32 (s,
H, ArNH), 8.87 (s, 6H, ArNH), 7.97 (d, 12H, J = 9.3 Hz, ArH), 7.57 (d, 12H, J = 9.3 Hz, ArH), 7.38 (d,
2H, J = 8.5 Hz, ArH), 6.83 (d, 12H, J = 8.5 Hz, ArH). 13 C NMR (125 MHz, DMSO-d6 , 25 C, ppm): δ
◦
52.24 (C=O), 146.70, 145.30, 141.20, 136.64, 125.30, 121.32, 120.23, 117.68. 31 P NMR (202 MHz, DMSO-d6 ,
◦
5
C, ppm): δ 9.69. MALDI MS m/z: Calcd for C78 H60 N21 O24 P3 , 1768.3610. Found: 1768.3280. Anal.
Calcd. for C78 H60 N21 O24 P3 : C, 52.98; H, 3.42; N, 16.63%. Found C, 52.95; H, 3.41; N, 16.59%.
3
.8. Synthesis of hexakis(1-oxyphenyl-3-(4-nitrophenyl) thiourea) cyclotriphosphazene (7)
To a solution of 4-nitrophenyl isothiocyanate (0.59 g, 3.25 mmol) in dry THF (10 mL) was added dropwise a
solution of compound 2 (0.39 g, 0.50 mmol) in dry THF (40 mL). The reaction mixture was stirred at ambient
temperature for 24 h under argon atmosphere. At the end of this time, to the yellow reaction mixture was
added CHCl3 (50 mL). The bright yellow solid formed was filtered and washed with CHCl3 (25 mL). The
◦
yellow product was obtained by drying the crude product. Yield 0.78 g (84%). mp 198–199 C. FTIR-ATR
νmax , cm 1): 3316 (N–H), 1595 and 1499 (Aromatic C=C), 1255 (N–C=S), 1159 (P=N), 952 (P–O–C). 1
−
H
(
◦
NMR (500 MHz, DMSO-d6 , 25 C, ppm): δ 10.39 (s, 6H, –NH), 10.23 (s, 6H, –NH), 8.16 (d, 12H, J = 8.7
Hz, ArH), 7.85 (d, 12H, J = 6.4 Hz, ArH), 7.54 (m, 12H), 6.99 (m, 2H). 13 C NMR (125 MHz, DMSO-d6 , 25
◦
31
C, ppm): δ 186.55 (C=S), 153.85, 146.14, 145.30, 143.20, 137.55, 128.51, 125.30, 123.12, 120.68.
P NMR
202 MHz, DMSO-d6 , 25 C): δ 9.67. MALDI MS m/z: Calcd for C78 H60 N21 O18 P3 S6 + (H ), 1865.7500.
Found: 1865.3250. Anal. Calcd. for C78 H60 N21 O18 P3 S6 : C, 50.24; H, 3.24; N, 15.77%. Found C, 50.19; H,
.22; N, 15.73%.
◦
+
(
3
Acknowledgment
¨
˙
The authors thank the Scientific and Technological Research Council of Turkey (TUBITAK) for the financial
support (112T278).
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