M.S. Refat et al. / Journal of Molecular Structure 995 (2011) 116–124
121
H
N+
Hd
He
N
N
N
Ha
O-
H
S
H
H
O
N
Ha
Hb
N
S
N+
NO2
NO2
H
OH
H
NH
Hb
Hd HO
He
Hc
Hf
O2N
O
Hc
Scheme 4. Formula of [(ArNH3þ)(QðOHÞꢀ2 )] charge transfer complex.
Hf
Scheme 2. Formula of [(ArNH3þ)(PiA–)] charge transfer complex.
and 14,6 (s, 1H, OH). 13C NMR (DMSO-d6): d = 115.5, 123.5,
126.2, 126.8, 127.8, 128.1, 128.4, 142.1, 145.8, 149.6, 154.9 and
164.7 (ArAC, C@C, C@N and C@O).
all proton as a result of complex formation. 1H NMR (DMSO-d6):
d = 4.8 (b, 3H, NHþ), 6.40 (d, 1H, J = 14.2 Hz, CH@CHe), 7.12 (t,
3
1H, J = 3.6, 3.6 Hz, thiophene – Hb), 7.31 (d, 1H, J = 3.6 Hz, thio-
phene – Hc), 7.59 (d, 1H, J = 5.4 Hz, thiophene – Ha), 7.75 (d, 1H,
J = 14.7 Hz, CHd@CH), 8.60 (s, 2H, Hf of benzene ring) and 12,01
(s, 1H, NH). 13C NMR (DMSO-d6): d = 120.5, 124.3, 125.2, 127.4,
128.3, 128.4, 129.1, 138.8, 141.2, 141.7, 155.1, 160.6 and 163.1
(ArAC, C@C, C@N and C@O).
3.4. Optical and scanning electron microscopes
Surface image using optical microscope (Fig. 6) demonstrate to
the porous structures of the surface of prepared charge transfer
complexes. Analysis of these images shows the size of pores to
be quite different with different acceptors. The chemical analysis
results by EDX for the formed charge transfer complexes show a
homogenous distribution of each acceptor. SEM examinations
were checked the surfaces of these CT-complexes that show a
small particles which tendency to agglomerates formation with
different shapes comparison with the start materials. The chemical
compositions of the free ArNH2 donor and charge transfer com-
plexes were determined using energy-dispersive X-ray diffraction
(EDX). In the EDX profile of these complexes (Fig. 7A–D), the peaks
of the carbon, nitrogen, oxygen, and sulfur elements, wþhich consti-
tute the molecules of ArNH2, [(ArNHþ3 )(PiA–)], [(ArNH3 )(QðOHÞ2ꢀ)]
and [(ArNHþ3 )(DNB–)] charge transfer complexes, are clearly identi-
fied confirming the proposed structures.
Similar results was obtained by the reaction of ArNH2 with dini-
trobenzene which, resulted in 5-hydroxy-6-(2-(thiophen-2-yl)vi-
nyl)-1,2,4-triazin-3-aminium 2,6-dinitro benzen-1-ide (Scheme
3), the 1H NMR showed disappearance of the signal of NH2 in
ArNH2 donor with appearance of broad signal at d = 4.5 ppm for
NHþ3 referring to the formation of salt between the electron poor
dinitrobenzene and the electron rich triazine derivative ArNH2.
The complex formed an activate NHAC@O M N@CAOH tautomer-
ization in triazine ring which, illustrated in the appearance of sig-
nal at d = 14.72 ppm for OH group and disappearþance of ring NH
signal. 1H NMR (DMSO-d6): d = 4.5 (b, 3H, NH3 ), 6.80 (d, 1H,
J = 10.2 Hz, CH@CHe), 7.13 (t, 1H, J = 3.6,3.6 Hz, thiophene – Hb),
7.20 (d, 1H, J = 1.8 Hz, dinitrobenzene– Hf), 7.51 (d, 1H, J = 5.4 Hz,
thiophene – Hc), 7.81 (d, 1H, J = 6.6 Hz, thiophene – Ha), 7.91 (t,
1H, J = 5.4, 5.6 Hz, dinitrobenzene – Hg), 8.65 (d, 1H, J = 10.2 Hz,
CHd@CH) and 14.72 (s, 1H, OH). 13C NMR (DMSO-d6): d = 118.5,
123.5, 126.3, 126.9, 127.9, 128.2, 129.3, 129.4, 131.5, 142.2,
147.9, 154.9 and 164.6 (ArAC, C@C, C@N and C@O).
For the reaction between the electron rich 1,4-qinol acceptor
and triazine derivative ArNH2 donor, the (5-hydroxy-6-[2-(thio-
phen-2-yl)ethenyl]-1,2,4-triazin-3-aminium 4-hydroxy phenolate)
(Scheme 4) is resulted with the same result that obtained from the
electron poor picric acid and dinitrobenzene. The 1H NMR showed
signals at d = 4.51, 6.56 and 8.66 ppm for NHþ3 , four aromatic quinol
protons and one quinol OH proton, respectively, with disappear-
ance of NH2 signal of ArNH2 donor. 1H NMR (DMSO-d6): d = 4.65
(b, 3H, NHþ3 ), 6.56 (s, 4H, ArH quinol), 6.81 (d, 1H, J = 16.2 Hz,
CH@CHe), 7.08 (t, 1H, J = 3.60, 4.80 Hz, thiophene – Hb,) 7.20 (d,
1H, J = 1.5 Hz, thiophene – Hc), 7.52 (d, 1H, J = 2.4 Hz, thiophene
– Ha), 7.82 (d, 1H, J = 15.9 Hz, CHd@CH), 8.66 (s, 1H, OH quinol)
3.5. Thermal analysis TGA/DSC
The simultaneous TGA/DSC analysis of the ArNH2(C9H7N4OS]
free
þdonor
and
their
respective
[(ArNHþ3 )(PiA–)],
[(ArNH3 )(QðOHÞꢀ2 )] and [(ArNHþ3 )(DNB–)] charge transfer com-
plexes were studied from ambient temperature to 800 °C under
nitrogen atmosphere using
a-Al2O3 as the reference (Fig. 8. The
free donor decomposed in three steps with seven (100, 225, 275,
400, 475, 530 and 750 °C) DSC peaks. The first decomposition step
at DSC = 100 and 225 °C endothermic, it loses a fragment of NH2
with a weight loss 7.73%. Then the endothermic peaks at 275 and
400 °C were assigned to the loss of H2S and C2H2 after the decom-
H
f
H
g
O2N
H
H
H
a
H
d
S
N
N
N
C-
H
H
f
N+
b
NO2
H
H
H
e
c
HO
Fig. 6. Optical microscopy photos of (A) ArNH2, (B) [(ArNHþ3 )(PiAꢀ)], (C)
[(ArNHþ3 )(QðOHÞ2ꢀ)] and (D) [(ArNHþ3 )(DNBꢀ)] complexes.
Scheme 3. Formula of [(ArNH3þ)(DNB–)] charge transfer complex.