4
S. N. KODLADY ET AL.
126.02 (C-22), 125.90 (C-24, C-26), 116.17 (C-6). LCMS
(ESI-MS) m/z: [M + H] Calculated for C21 H17N3O3 S,
391.44 Found: 392.05.
2.4. DFT calculations
The quantum chemical calculations of the DFT on the
condensation reaction by opening the ring of the ben-
zamide hydrazone receptors were performed to help the
study of the optical activity and method of complexation
of the 3-[aryl substituted hydrazinyl]-3-oxo-1-(thio-
phene-2-yl) prop-1-en-2-ylcyanide ion with benzamide
hydrazone receptors. The molecular structure modifica-
tions and frontier molecular orbital properties at DMF
solvent process performed by DFT with B3LYP exchange
with Maestro-MS applied 6–311 G basic sets.
(R4) 3-[(2E)-2-(Biphenyl-4-ylmethylidene) hydrazi-
nyl]-3-oxo-1-(thiophen-2-yl) prop-1-en- 2-ylbenzamide.
Pale yellow solid; yield 84%; M.P.: 240–242 C: IR,
υ cm−1:3312–3273 (NH), 3018 (sp2 – CH), 2978 (sp3-CH),
1637 (C = O), 1604 (C = O), 1531 (C = N), 1552–1465 (C = C,
aromatic skeletal vibration). 1 H NMR (DMSO d6, 400 MHz, δ
ppm): 7.15 (s, 1 H, CH), 7.39–8.14 (m,17 H, Ar–H), 8.48 (s, 1 H,
CH = N, imine), 9.95 (s, 1 H, NH), 11.64 (s, 1 H, NH). 13 C NMR
(DMSO-d6, 100 MHz, δ ppm): 166.60 (C = O, C-11), 161.91
(C = O, C-9), 147.61 (C-21), 141.95 (C-25), 139.84 (C-28),
137.16 (C-5), 134.15 (C-7), 134.03 (C-13), 133.06 (C-22),
132.25 (C-16), 130.99 (C-2), 129.50 (C-23, C-27), 128.83
(C-30, C-32, C-4), 128.54 (C-15, C-7), 128.34 (C-3), 128.08
(C-24, C-26), 127.53 (C-29, C-33), 127.15 (C-31), 126.68
(C-14, C-18), 126.33 (C-6). LCMS (ESI-MS) m/z: [M + H]
Calculated for C27H21N3O2S, 451.54 Found: 452.10 [25].
3. Results and discussion
3.1. UV-visible titration studies of receptor R1 with
cyanide ion in DMF (organic) and DMF: H2O (9:1)
organo-aqueous medium
The UV-visible absorption band is one of the most
important output signals used in the ion–receptor stu-
dies, as it aids in the detection of target species with the
represents the UV-Visible absorption spectra of receptor
R1, indicating its molecular interaction with various
2.2. UV-visible study of the receptor (R1-R4) with
anions
All the UV-Visible experiments of the receptors (R1-R4)
anions (CN−, Br−, I−, HSO4 , Cl−, OH−, F−, AcO−, NO2− and
−
with various anions (Br−, I−, HSO4 , Cl−, OH−, F−, AcO−,
−
−
NO3 ) as their tetra-n-butylammonium (TBA) salts in
−
NO2− and NO3 ) as their tetrabutylammonium salts were
DMF and DMF:H2O (9:1, v/v) media. As it is clear from
the spectra, receptor R1 shows absorption maximum at
330 and 326 nm in DMF and DMF: H2O (9:1, v/v) media,
respectively, which was shifted to a longer wavelength
of 382 and 376 nm, upon the addition of CN− ions
indicating their interaction with receptor R1. However,
carried out in DMF and DMF: H2O (9:1, v/v). Any changes
in the UV-Visible spectra of the synthesised compounds
on the addition of tetrabutylammonium salts of anions
(1.0 × 10−2 M), keeping the ligand concentration con-
stant (2.5 × 10−5 M), were recorded using Shimadzu UV-
2550 spectrometer. UV-Visible titration experiments
were recorded by continuously adding different anion
equivalents via a micropipette to a 2 ml (2.5 × 10−5 M)
solution of the receptors (R1-R4) in DMF and DMF: H2
O (9:1, v/v) medium and their absorption spectra were
analysed.
no such interactions of other ions (Br−, I−, HSO4 , Cl−,
−
OH−, F−, AcO−, NO2 and NO3 ) with receptor R1 were
evidenced from the spectra. Similar results were
observed for receptors R2-R4 and the corresponding UV-
Visible absorption spectra are depicted in Fig-S9, S22
and S35 (information from ESI*).
−
−
To quantitatively study the cyanide-sensing ability of
receptors R1-R4 in DMF and DMF: H2O (9:1, v/v) mixture,
monitoring was observed by using 2.5 × 10−5 M solution
of receptors R1-R4 upon the incremental addition of
cyanide anions (1 × 10−2 M). The results depicted in
Figure 2(a,b) for receptor R1 show a bathochromic shift
of λICT = 52 nm (330–382 nm) and λICT = 50 nm (326–-
376 nm) in DMF and DMF:H2O (9:1, v/v) media, respec-
tively. The incremental addition of CN− ions also effects
on the intensities of the absorption peaks, as it is seen in
the UV-Visible absorption spectra, the intensity of
absorption peak of R1 at 330 nm in DMF gradually
decreases, whereas the intensity of new peak at
382 nm increases up to the addition of 0.0–1.8
2.3. NMR titration experiments
1
The H NMR titration studies have established the
sensing of cyanide ions by R1 receptor through the
development of receptor-cyanide ion complex. To
confirm the sensing mechanism, the H NMR titration
1
study was conducted with the receptor R1 in DMSO-d6
by adding 0.5, 1.5 and 2.5 equivalents of cyanide ions,
1
and the H NMR titration spectra have been shown in