Synthesis of 4-styrylphthalhydrazides and their chemiluminescence reaction. Emitters and chemiluminescence efficiency highly dependent on electronic nature of styryl goups

Article abstract of DOI:10.1002/jhet.5570420605

A series of 4-styrylphthalhydrazides were synthesized and their chemiluminescence reactions were investigated. The chemiluminescence quantum yields as well as the emitters were variable depending on the electronic nature of the terminal substituents attac

Full text of DOI:10.1002/jhet.5570420605

Sep-Oct 2005
1063
Synthesis of 4-Styrylphthalhydrazides and Their Chemiluminescence
Reaction. Emitters and Chemiluminescence Efficiency Highly Dependent
on Electronic Nature of Styryl Goups
Jiro Motoyoshiya,* Kazuya Yokota, Takuro Fukami, Shoji Konno, Aya Yamamoto,
Masanori Hotta, Ryu Koike, Sachiko Yoshioka, Yoshinori Nishi, and Hiromu Aoyama
Department of Chemistry, Faculty of Textile Science and Technology, Shinshu University,
Ueda, Nagano, 386-8567, Japan
Received December 2, 2004
A series of 4-styrylphthalhydrazides were synthesized and their chemiluminescence reactions were inves-
tigated. The chemiluminescence quantum yields as well as the emitters were variable depending on the elec-
tronic nature of the terminal substituents attached on the styryl groups. It was revealed that the excited phtha-
late ions were the emitters when they were highly fluorescent, while the energy transfer chemiluminescence
from the excited phthalate ions to the phthalhydrazide anions took place when the fluorescence of the corre-
sponding phthalate ions were very weakly fluorescent.
J. Heterocyclic Chem., 42, 1063 (2005).
Of the artificial chemiluminescent compounds, luminol
As illustrated in Scheme 1, a series of dimethyl 4-
styrylphthalates, prepared by the Horner-Wadsworth-
Emmons reaction of dimethyl (4-dimethylphospho-
nomethyl)phthalate and various aromatic aldehydes, were
reacted with hydrazine to give 4-styrylphthalhydrazides
(4a-g). With an expectation of increasing the chemilumi-
nescence efficiency due to an increase of the fluorescence
intensity of the phthalate ion by the prolonged conjugation
[9], 4g having a distyrylbenzene moiety was designed.
The fluorescence intensity of the 4-styrylphthalate ions,
the most likely emitters in the phthalhydrazide chemilumi-
nescence, is strongly dependent on the electronic nature of
the terminal substituents (Table 1). The phthalates with
electron-donating substituents exhibit fluorescence in a
(5-amino-2,3-dihydro-1,4-phthalazinedione, 1) (Figure 1)
is the most popular one [1], which has been used in practi-
cal applications as a means of chemical analysis [2]. The
luminol chemiluminescence is based on light emission
from the excited 3-aminophthalate ion (2) generated by
oxidation with hydrogen peroxide or atmospheric oxygen
in the presence of bases and catalysts [3]. This peculiar
chemiluminescence property and its practical value have
attracted continuous interest and prompted many chemists
to investigate its reaction in detail [4] and to exploit related
chemiluminescent compounds to date [5]. For instance,
several modified phthalhydrazides, some of which display
chemiluminescence stronger than luminol, have been syn-
thesized [3a,6]. In contrast, phthalhydrazide (3), struc-
turally the parent compound of luminol but lacking the
amino group, also weakly emits light by oxidation, in
which the emitter is not a non-fluorescent phthalate ion,
but the excited phthalhydrazide monoanion generated by
energy transfer from the excited phthalate ion as reported
by White et. al [7]. They also reported a very unique reac-
tion, photochemistry without light, of 4-styrylphthalhy-
drazide (4a), in which the cis-trans isomerization occurred
with a low efficiency [8]. Such diversity in the phthalhy-
drazide chemiluminescence encouraged us to synthesize
various 4-styrylphthalhydrazides and investigate their
chemiluminescence reaction with expectation of finding
new aspects.
longer wavelength region, in addition to the higher Φ ,
F
than those without such substituents. This phenomenon is
due to an increase in push-pull character for the conjugated
system. Therefore, chemiluminescence property is also
expected to vary with the terminal substituents.
The reactions of the 4-styrylphthalhydrazides (4a-g) in
the aerobic DMSO solution in the presence of tert-BuOK
provided chemiluminescence with various intensities
depending on the structures. These chemiluminescence
reactions produced the corresponding phthalate ions as the
final products that were identified by their UV spectra. The
4-styrylphthalhydrazides 4a and 4b showed a very weak
light emission with a much longer wavelength around 530
nm than was expected from the corresponding phthalate

1064
J. Motoyoshiya, K. Yokota, T. Fukami, S. Konno, A. Yamamoto, M. Hotta,
R. Koike, S. Yoshioka, Y. Nishi, and H. Aoyama
Vol. 42

Sep-Oct 2005
Synthesis of 4-Styrylphthalhydrazides and Their Chemiluminescence Reaction
1065
ions. As shown in Figure 2, the chemiluminescence spec-
trum of 4a was different from the fluorescence spectrum of
the corresponding phthalate ion but agreed with the fluo-
rescence spectrum (emission at λmax. 530 nm) measured
immediately after 4a and tert-BuOK were mixed in
DMSO. The resulting solution after a few hours showed
only the fluorescence corresponding to the phthalate ion
(emission at λmax. 363 nm). Figure 3 shows the time
course of the fluorescence spectra for the reaction of 4a.
chemiluminescence reaction and that of the parent phthal-
hydrazide (3) [8], in which the phthalhydrazide monoanion
exhibited the fluorescence at 526 nm and was stable
toward oxygen, the fluorescence at 530 nm observed here
would be ascribed to the monoanion of 4a that is in an
equilibrium state with its dianion finally oxidized to the
phthalate ion as shown in Scheme 2. Because of the very
weakly fluorescent property of the phthalate ions (7) in the
case for 4a and 4b, the more fluorescent, excited monoan-
The fluorescence at 530 nm formed initially almost main-
tained its intensity during several ten minutes with a bit of
decay, while that of the phthalate ion at 363 nm increased
constantly. Considering the similarity of the present
ion (5) would be produced by an energy transfer from the
excited phthalate ions (7*). Such an energy transfer chemi-
luminescence was also reported in the reaction of luminol
[10], in which a strongly fluorescent dye such as fluores-

1066
J. Motoyoshiya, K. Yokota, T. Fukami, S. Konno, A. Yamamoto, M. Hotta,
R. Koike, S. Yoshioka, Y. Nishi, and H. Aoyama
Vol. 42
cein was an energy acceptor. As expected, a bright yellow
chemiluminescence was also observed when fluorescein
was used as an energy acceptor in the reaction of 4a or 4b.
In the reactions of 4c and 4d, the dual light emission
around 370 nm and 530 nm, ascribed to the phthalate ions
and the phthalhydrazide monoanions, respectively, could
be detected as shown in Figure 4. In these cases, both
direct and indirect (energy transfer) chemiluminescence
reactions are involved owing to an increase of fluores-
cence character of the phthalate ions compared to the case
of 4a and 4b.
The chemiluminescence reaction in an aqueous medium
was also examined employing 4f. In contrast to the reac-
tion under the anhydrous conditions, the emission effi-
ciency of 4f was inferior to luminol by one tenth and the
emission red-shifted by ca. 50 nm [11] when the reaction
was carried out in an aqueous DMSO solution using potas-
sium persulfate and potassium carbonate as the oxidizing
agent and base.
In summary, a series of 4-styrylphthalhydrazides were
prepared and their chemiluminescence reactions were
examined, where modulation of the chemiluminescence
efficiency as well as the emitter by the electronic nature of
the terminal substituents was conducted. The strongly
electron-donating character is coincident with the increase
On the contrary, 4e-g bearing the strongly electron-
donating substituents produced the chemiluminescence
only based on the fluorescence of the corresponding potas-
sium phthalates, whose chemiluminescence quantum
in the Φ of the corresponding phthalate ions by a contri-
F
bution of an electronic push-pull system, which provides
an efficient chemiluminescence with the excited phthalate
ions being the emitters. On the other hand, the energy
yields (Φ ) were comparable to the luminol chemilumi-
CL
nescence (Table 1). Figure 5 shows a good agreement of
the fluorescence and chemiluminescence spectra of the
reaction of 4f. Especially, 4g showed the most effective
chemiluminescence by ca. 4 times larger than luminol. The
fast decay of the anions of the phthalhydrazides 4e-g
revealed by monitoring of their absorptions suggests that
their anions are easily oxidized to the phthalate ions. Since
the phthalhydrazide chemiluminescence reaction is
believed to involve a superoxide anion formed by an elec-
tron transfer from the phthalhydrazide dianion to molecu-
lar oxygen at the initial stage [4f], the electron-donating
substituent would promote an electron transfer from the
hydrazide dianion to a molecular oxygen and the sequen-
tial oxidation process, resulting in the fast formation of the
excited phthalate ions. In addition, a photoisomerization
from E-4f to Z-4f was detected in ca. 3% yield during this
chemiluminescence reaction similarly to the reaction of 4a
as reported by White et al. [8].
transfer chemiluminescence takes place when Φ of the
F
phthalate ions is small.
EXPERIMENTAL
1
13
The H NMR and C NMR spectra were recorded at 400
MHz, and chemical shifts (δ) were given in ppm relative to
tetramethylsilane (TMS) as the internal standard. Mass spectra
were determined at an ionizing voltage of 70 eV. All phthalhy-
drazides did not melt bellow 260 °C. The CL quantum yields
were measured by the procedure previously reported [12].
General Procedure for Synthesis of 4-Styrylphthalhydradide (4a)
[8].
The Arbuzov reaction of trimethyl phosphite (2.83 mL, 24.0
mmol) and dimethyl 4-bromomethylphthalate (6.89 g, 24.0
mmol) was carried out by heating their mixture for 18 h at 120
°C. The residue was purified by column chromatography on sil-

Sep-Oct 2005
Synthesis of 4-Styrylphthalhydrazides and Their Chemiluminescence Reaction
1067
ica gel to give the pure phosphonate (3.95 g, 52 %), a part of
which (1.0 g, 3.16 mmol) was subjected to the Horner-
Wadsworth-Emmons reaction with benzaldehyde (0.26 mL, 2.53
mmol) in the presence of tert-BuOK (0.43 g, 3.79 mmol) in THF
(6 mL) for 15 h at room temperature with stirring. After removal
of the solvent, benzene was added and the organic layer was
washed with saturated ammonium chloride. Standard workup
consisting of drying over Na SO , concentration under reduced
Anal. Calcd. For C H N O : C, 69.38; H, 4.79; N, 9.52.
17 14 2 3
Found: C, 69.38; H, 4.67; N, 9.69.
4-(2',4'-Dimethoxystyryl)phthalhydrazide (4e).
This compound was obtained as a pale-yellow powder in 41 %
-1
1
yield, ir: NH 3256, CO 1608 cm ; H nmr (DMSO-d ): δ_3.81
6
(s, 3H, CH O), 3.89 (s, 3H, CH O), 6.58-6.62 (m, 2H, 2', 5'-H),
3
3
6.70 (br, 2H, NH), 7.31 (d, 1H, (CH O) C H CH=CH, J = 16.6
3
2 6 3
2
4
Hz), 7.55 (d, 1H, (CH O) C H CH=CH, J = 16.6 Hz), 7.66 (d,
1H, 4'-H, J = 8.8 Hz), 7.96 (d, 1H, 5-H, J = 8.4 Hz), 8.03 (d, 1H,
pressure, and recrystallization gave dimethyl 4-styrylphthalate
(0.49 g, 65%). Thus prepared dimethyl 4-styrylphthalate ester
(0.3 g, 1.01 mmol) was dissolved in warm triethylenglycol (5
ml), and distilled hydrazine (1.62 mL, 50.6 mmol) was added to
the solution. After heating for 1 h at 100 °C, hexane was added
until the 4-styrylphthalhydrazide was precipitated and the excess
reactants were removed in vacuo at 100 °C to give a yellow pow-
3
2 6 3
13
6-H, J = 8.4 Hz), 8.14 (s, 1H, 3-H); C nmr (DMSO-d ): δ
6
55.68, 55.98, 98.73, 106.19, 118.14, 122.65, 125.59, 125.91,
126.28, 127.00, 128.16, 129.27, 129.37, 141.61, 156.32, 156.62,
+
158.46, 161.25; ms: m/z 324 (M ).
Anal. Calcd. For C H N O : C, 66.66; H, 4.97; N, 8.64.
18 16
2 4
-1
1
der (0.077 g, 29 %), ir: NH 3302, CO 1605 cm ; H nmr:
Found: C, 66.54; H, 5.04; N, 8.85.
(DMSO-d ): δ 6.30 ( br, 2H, NH), 7.32 (t, 1H, 4”-H, J = 7.6 Hz),
6
4-(4'-Dimethylaminostyryl)phthalhydrazide (4f).
This compound was obtained as a yellow powder in 59 %
7.42 (t, 2H, 3', 5'-H, J = 7.6 Hz), 7.47 (d, 1H, PhCH=CH, J = 16.5
Hz), 7.52 (d, 1H, PhCH=CH, J = 7.69 Hz), 7.69 (d, 2H, 2', 6'-H,
J = 7.6 Hz), 8.06 (d, 1H, 5-H, J = 7.6 H), 8.09 (d, 1H, 6-H, J = 7.6
-1 1
yield, ir: NH 3190, CO 1600 cm ; H nmr (DMSO-d ): δ 2.95 (s,
6
13
Hz), 8.24 (s, 1H, 3-H); C NMR (DMSO-d ): δ 123.54, 126.20,
6H. (CH ) N), 6.30 (br, 2H, NH), 6.74 (d, 2H, 2', 5'-H, J = 8.8
6
3 2
127.27, 127.32, 127.69, 128.59, 128.78, 129.12, 129.75, 131.65,
Hz), 7.14 (d, 1H, (CH ) NC H CH=CH, J = 16.4 Hz), 7.38 (d,
3 2 6 4
136.96, 140.89, 156.01, 156.35; hrms (EI): calcd for
1H, (CH ) NC H CH=CH, J = 16.4 Hz), 7.51 (d, 2H, 3', 4'-H, J
3 2 6 4
= 8.8 Hz), 8.01 (s, 2H, 5,6-H), 8.13 (s, 1H, 3-H); C nmr
+
13
C H N O (M ) 264.0898, found 264.0907.
16 12
2 2
(DMSO-d ): δ 40.23, 112.48, 122.36, 122.51, 124.68, 126.04,
6
4-(4'-Chlorostyryl)phthalhydrazide (4b).
126.14, 128.49, 128.86, 129.35, 132.26, 142.08, 150.76, 155.80,
+
This compound was obtained as a pale-yellow powder in 46%
156.01; ms: m/z 307 (M ).
-1
1
yield, ir: NH 3178, CO 1655 cm ; H nmr (DMSO-d ): δ 5.70
Anal. Calcd. For C H N O : C, 70.34; H, 5.58; N, 13.67.
6
18 17
3 2
(br, 2H, NH), 7.47 (d, 2H, 2', 6'-H J = 8.4 Hz), 7.51 (s, 2H,
CH=CH), 7.72 (d, 2H, 3', 5'-H, J = 8.4 Hz), 8.07 (d, 1H, 5-H, J =
Found: C, 70.73; H, 5.43; N, 13.99.
4-{4'-[4''-(2-Ethylhexyloxy)styryl]styryl}phthalhydrazide (4g).
This compound was obtained as a yellow powder in 54 % yield,
13
8.4 Hz), 8.09 (d, 1H, 6-H, J = 8.4 Hz), 8.24 (s, 1H, 3-H); C nmr
(DMSO-d ): δ 123.63, 126.16, 127.17, 128.48, 128.93, 129.13,
6
-1
1
129.80, 129.96, 130.43, 132.95, 135.95, 140.79, 155.61, 156.02;
ir: NH 3192, CO 1593, 1654 cm ; H nmr (DMSO-d ): δ 0.88-
6
+
ms: m/z 298 (M ).
1.71 (m, 15H, C H CH O, 15H), 3.89 (d, 2H, C H CH O, J =
7
15
2
7
15
2
Anal. Calcd. for C H ClN O : C, 64.33; H, 3.71; N, 9.38.
6.0 Hz), 6.96 (d, 2H, 2'''', 6''''-H, J = 8.8 Hz), 7.11 (d, 1H, C H
16 11
2
2
7
15
CH OC H CH=CH, J = 16.4 Hz), 7.26 (d, 1H, C H
Found: C, 64.47; H, 3.76; N, 9.45.
2
6
4
7
15
CH OC H CH=CH, J = 16.4 Hz), 7.50 (d, 2H, CH=CHC H -
2
6
4
6 3
4-(3'-Methoxystyryl)phthalhydrazide (4c).
(CONH) , J = 16.4 Hz), 7.51 (d, 2H, CH=CHC H (CONH) , J =
2
6
3
2
This compound was obtained as a pale-yellow powder in 46 %
16.4 Hz), 7.55 (d, 2H, 3'', 5''-H, J = 8.8 Hz), 7.61 (d, 2H, 2", 6'-H, J
= 8.2 Hz), 7.69 (d, 2H, 3', 5'-H, J = 8.2 Hz), 8.05 (d, 1H, 5-H, J =
8.0 Hz), 8.15 (d, 1H, 6-H, J = 8.0 Hz), 8.22 (s, 1H, 3-H); C nmr
-1
1
yield, ir: NH 3198, 3310, CO 1658 cm ; H nmr (DMSO-d ): δ
6
13
3.82 (s, 3H, OCH ), 6.50 (br, 2H, NH), 6.89 (d, 1H, 6'-H, J = 7.6
3
(CDCl ), δ (ppm): 11.12, 14.08, 23.06, 23.89, 29.10, 30.55, 39.41,
Hz), 7.25 (d, 1H, 4'-H, J = 7.6 Hz), 7.28 (s, 1H, 2'-H), 7.32 (dt,
3
52.55, 52.72, 70.65, 114.82, 125.75, 125.97, 126.64, 127.23,
127.79, 128.16, 128.37, 128.88, 129.35, 129.72, 129.80, 131.67,
133.40, 135.25, 138.07, 140.84, 159.38, 167.39, 168.53; ms: m/z
1H, 5'-H, J = 7.6 Hz), 7.44 (d, 1H, CH OC H CH=CH, J = 16.6
3
6 4
Hz), 7.52 (d, 1H, CH OC H CH=CH, J = 16.6 Hz), 8.06 (s, 2H,
3
6 4
13
5, 6-H), 8.24 (s, 1H, 3-H); C nmr (DMSO-d ): δ 55.45, 112.21,
114.51, 119.87, 123.64, 126.22, 127.46, 128.03, 129.23, 129.65,
6
+
494 (M ). The elemental analysis did not give the correct values.
130.10, 131.49, 138.44, 140.75, 156.19, 156.51, 159.97; ms: m/z
294 (M ).
Measurements of the Chemiluminescence Quantum Yields.
+
Calibration of a photomultiplier was done by the procedure
previously reported [12]. For a typical run, a solution (1.0 mL)
containing 4 (1.00 x 10 M) in distilled DMSO was placed in a 1
Anal. Calcd. For C H N O : C, 69.38; H, 4.79; N, 9.52.
Found: C, 69.28; H, 4.95; N, 9.46.
17 14
2 3
-5
4-(4'-Methoxystyryl)phthalhydrazide (4d).
This compound was obtained as a pale-yellow powder in 79%
x 1 cm quartz cuvette in front of the photomultiplier in exactly
the same geometry. Photon-counting was initiated simultane-
ously with the injection of a solution (1.0 mL) of tert-BuOK
-1 1
yield, ir: NH 3340, CO 1600 cm ; H nmr (DMSO-d ): δ 3.80 (s,
6
-2
(2.00 x 10 M) in DMSO into the cuvette, and the data collection
3H), 6.30 (br, 2H, NH), 6.98 (d, 2H, 1', 5'-H, J = 8.8 Hz), 7.32 (d,
was continued for 2 h.
1H, CH OC H CH=CH, J = 16.4 Hz), 7.46 (d, 1H,
3
6
4
CH OC H CH=CH, J = 16.4 Hz), 7.64 (d, 2H, 2', 4'-H, J = 8.8
3
6 4
Acknowledgement.
Hz), 8.02 (d, 1H, 5-H, J = 8.0 Hz), 8.04 (d, 1H, 6-H, J = 8.0 Hz),
13
8.18 (s, 1H, 3-H); C (DMSO-d ): δ 55.56, 114.62, 122.95,
This work was partially supported by Grant-in-Aid by the
Ministry of Education, Culture, Sports, Science, and Technology
(14B1-30, 16550122).
6
125.26, 126.08, 126.62, 128.71, 128.85, 129.58, 129.64, 131.50,
141.50, 155.68, 155.98, 159.86; ms: m/z 294 (M ).
+

1068
J. Motoyoshiya, K. Yokota, T. Fukami, S. Konno, A. Yamamoto, M. Hotta,
R. Koike, S. Yoshioka, Y. Nishi, and H. Aoyama
Vol. 42
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