€
500
O. Arslan et al. / Journal of Molecular Structure 1149 (2017) 499e509
ꢁ
density functional theory (DFT and TD-DFT). In addition, the in-
concentrated sulphuric acid (3 mL at 50 C)). The mixture was
2
þ
2þ
2þ
2þ
ꢁ
teractions between 8HQA and the cations (Ca , Mg , Cu , Co
,
stirred for an additional 2 h at 0 C. Excess nitrous acid was
2
þ
2þ
2þ
2þ
Sn , Ni , Cd and Hg ) were also investigated by UV-Vis and
naked-eye. Based on our study, we were surprised to find that no
significant selectivity was observed towards cations.
consumed by the addition of urea. The resulting diazonium salt was
cooled in salt/ice mixture. After diazotization was complete the
diazo liquid was slowly added to vigorously stirred solution of 8-
hydroxyquinoline (2 mmol) in potassium hydroxide (2 mmol in
4
0
mL methanol and 2 mL and water). The solution was stirred at
e5 C for 2 h. After 2 h, the pH of the reaction mixture was
2
. Experimental
ꢁ
maintained at 4e6 by the addition of saturated sodium carbonate
solution. The mixture was stirred for one hour at room tempera-
ture. After that, the resulting solid was filtered, washed with cold
water and dried. Recrystallization from ethanol gave dark brown
2
.1. Materials and instrumentation
The chemicals used in the syntheses of all compounds were
obtained from Sigma-Aldrich Chemical Company (USA) and were
used without further purification. All solvents used were of
analytical grade. The solvents were dried according to standard
procedures. All reactions were magnetically stirred and monitored
by thin layer chromatography (TLC), using Merck silica gel (60
F254) plates (0.25 mm) and visualized under Ultraviolet light (UV).
FT-IR (ATR) spectra were recorded on Perkin-Elmer Spectrum 100
ꢁ
-l
solid. Yield 50%; mp 232 C; FT-IR (ATR)
H), 2218 (C^N), 1732 (C]O); HNMR (DMSO-d
y
/cm 3249 (N-H), 2960 (C-
1
6
, 300 MHz) 9.37
d
(
d
d, J ¼ 8.56 Hz, 1H),
d
9.00 (d, 2.60 Hz 1H),
d
8.14 (d, J ¼ 8.53 Hz, 2H),
8.06 (d, J ¼ 8.59 Hz, 1H),
d
7.92 (d, J ¼ 8.53 Hz, 2H),
d
7.80 (m,
1
3
J ¼ 8.52 Hz, 1H),
d
7.26 (d, J ¼ 8.56 Hz, 1H),
d
2.71 (s, 3H) ppm;
C
NMR (DMSO-d
6
, 75 MHz) d 176.5, 159.1, 154.7, 149.6, 139.2, 138.3,
ꢀ
1
138, 132.4, 129.7, 129.3, 128.6, 128.3, 123.9, 123.1, 115.9, 113.8, 113.7,
12.3, 84.3, 24.7 ppm; HRMS (ESI, CH CN) (C20 O) found.
40.1200, calc.340.1198.
FT-IR spectrophotometer (
recorded on a Bruker Avance 300 Ultra-Shield in DMSO-d
Chemical shifts are expressed in units (ppm). UltravioleteVisible
UV-vis) absorption spectra were recorded on Shimadzu Corpora-
n, are in cm ). NMR spectra were
1
3
14 5
H N
6
.
3
d
(
tion, Kyoto Japan UV-1800 240V spectrophotometer (Gazi Univer-
sity Department of Chemistry, Turkey). Mass spectra were recorded
on Waters-LCT-Premier-XE-LTOF (TOF-MS) instruments; in m/z
2.4. Computational methods
All calculations were carried out using the Gaussian09 program
package [33]. The molecule geometry was optimized at HF/631 g
(
rel. %) (Gazi University Laboratories, Department Pharmacological
Sciences). Chemical shifts are expressed in units (ppm) with tet-
ramethylsilane (TMS) as the internal reference. Coupling constant
J) is given in hertz (Hz). Signals are abbreviated as follows: singlet,
ꢁ
d
with the rotations C8-C10-C13-C15 torsion angles by 20 intervals
ꢁ
in the range of 0-360 to find the most possible conformation. Then,
(
this conformation was taken as a starting geometry and re-
optimized using B3LYP/631 þ g(d,p) [34,35] in gas phase and
different solvents. It is confirmed that no imaginary vibrational
frequencies at the optimized geometries to indicate true minima of
the potential energy surface. The absorption spectra of the mole-
cule and its deprotonated forms were calculated by using the time-
dependent density functional method (TD-DFT) and using self-
consistent reaction field (SCRF) method, based on the polarizable
continuum model (PCM) [36,37].
s; doublet, d; triplet, t, multiplet, m. The melting points were
measured on Electrothermal IA9200 apparatus and uncorrected.
Thermal analyses were performed with a Shimadzu DTG-60H
ꢁ
ꢁ
ꢀ1
system, up to 600 C (10 C min ) under a dynamic nitrogen at-
ꢀ
1
mosphere (15 mL min ). Typically, aliquots of a freshly prepared
ꢀ
standard solutions of the alkylammonium salt of the anions (CN ,
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
F , Cl , I , AcO , HSO and H PO ) and of chloride salt of cations
4 2
4
2
þ 2þ 2þ 2þ 2þ 2þ 2þ 2þ
(
Ca , Mg , Cu , Co , Sn , Ni , Cd and Hg ) were added,
1
and their various UV-vis spectra were recorded. H NMR titrations
for anions were carried out in DMSO-d solution.
6
3. Results and discussion
2.2. Synthetic procedures
3.1. Synthesis and characterization
2
-(1-(4-aminophenyl)ethylidene)malononitrile (1) was syn-
The synthesis of 8HQA was performed by stepwise procedure as
thesized by using literature method [32].
illustrated in Scheme 1.1 was synthesized using Microwave Irradi-
ation Method (MWI) with excellent yield. In addition, 8HQA was
prepared by coupling 8-hydroxyquinoline with diazotized 1 in
nitrosyl sulphuric acid. The structure of 8HQA was confirmed by FT-
2
.3. The synthesis of (E)-2-(1-(4-((8-hydroxyquinolin-5-yl)
diazenyl)phenyl)ethylidene)malononitrile (8HQA)
1
13
IR, H NMR, C NMR and HRMS techniques. The spectral data were
consistent with the proposed structure (Supplementary data,
Figs. S1eS4). The prepared dye may show two possible tautomeric
forms, namely azo form A and hydrazone B as shown in Scheme 2.
After deprotonation of two tautomeric forms, it may be stable as
common anion mesomeric structure C (Scheme 2). In some
2
mmol 2-(1-(4-aminophenyl)ethylidene)malononitrile (1) was
dissolved in hot glacial acetic acid-propionic acid mixture (2:1,
ꢁ
9
.0 mL) and was rapidly cooled in an ice/salt bath to ꢀ5 C. The
liquor was then added in portions during 30 min to a cold solution
of nitrosyl sulphuric acid (prepared from sodium nitrite (0.15 g) and
Scheme 1. Synthesis of (E)-2-(1-(4-((8-hydroxyquinolin-5-yl)diazenyl)phenyl)ethylidene)malononitrile (8HQA).
Arslan, ?mer
