Photochemical E(trans)-Z(cis) isomerization in 9-anthraceneacrylic esters

Article abstract of DOI:10.1246/bcsj.75.2487

Several (1-6) 9-anthraceneacrylic esters were synthesized in order to study photochemical E(trans)-Z(cis) isomerization. All of the compounds 1-6 underwent selective E-to-Z isomerization upon direct excitation (> 400 nm) in organic solvents, leading to the formation of a thermodynamically less stable Z isomer over 96%. Triplet sensitized isomerization selectively produces the Z-to-E isomer in over 98%. The higher quantum yield of isomerization observed in the triplet-sensitized Z-to-E isomerization process informs us that a "quantum chain" process is in operation. Fluorescence data generated on all compounds indicate that the E-to-Z isomerization process involves a charge-transfer or polar singlet excited state.

Full text of DOI:10.1246/bcsj.75.2487

c. Jpn.
e Chemical © 2002 The Chemical Society of Japan
Bull. Chem. Soc. Jpn., 75, 2487–2495 (2002) 2487
ciety of Ja-
n
e Chemical
ciety of Ja-
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Photochemical E(trans)–Z(cis) Isomerization in 9-Anthraceneacrylic
Esters
E-Z Isomerization in 9-Anthraceneacrylic Esters
M. Janaki Ram Reddy et al.
Majjigapu Janaki Ram Reddy, Uppalanchi Srinivas, Kolupula Srinivas, Vummadi Venkat Reddy, and
0
2
Vaidya Jayathirtha Rao*
8
9
7
5
Organic Chemistry Division Ⅱ, Indian Institute of Chemical Technology, Hyderabad- 500 007, India
SJA8
0
9-2673
(
Received April 1, 2002)
0
0
0
81
Several (1–6) 9-anthraceneacrylic esters were synthesized in order to study photochemical E(trans)–Z(cis) isomer-
2
2
ization. All of the compounds 1–6 underwent selective E-to-Z isomerization upon direct excitation (> 400 nm) in organ-
ic solvents, leading to the formation of a thermodynamically less stable Z isomer over 96%. Triplet sensitized isomeriza-
tion selectively produces the Z-to-E isomer in over 98%. The higher quantum yield of isomerization observed in the trip-
let-sensitized Z-to-E isomerization process informs us that a “quantum chain” process is in operation. Fluorescence data
generated on all compounds indicate that the E-to-Z isomerization process involves a charge-transfer or polar singlet ex-
cited state.
1
1
–4
Photochemical cis–trans isomerization of stilbenes,
Table 1. Isomer Composition upon Direct Excitation of 1E–
6E
5–7
diphenyl polyenes,
vitamin-A, and vitamin-A related
compounds have been studied for the past several years.
Mainly because of its role as (i) models for photoisomerization
around a double bond related to biological systems, (ii) a
practical application of the reaction in vitamin A and vitamin
and (iii) as possible candidates for
The photochemical cis–trans
isomerization reaction in stilbene derivatives is still an interest-
The photochemical cis–trans
isomerization of diarylethylenes is found to be interesting be-
cause of certain compounds exhibiting “one-way” cis-to-trans
isomerization involving a triplet excited state leading to
quantum chain isomerization process. Indeed, less attention is
being paid towards understanding the cis-trans isomerization
process in arylethylenes derivatives, carrying electron-with-
8,9
Compound
Solvent
Time/min
05
λex/nm E/% Z/%
1
0
1E
CH CN
> 400
> 400
> 400
> 300
~350
> 400
> 400
> 300
~350
> 400
> 300
> 400
> 400
> 300
> 400
> 400
> 300
> 400
> 400
> 300
> 400
> 400
> 300
> 400
42
20
04
56
52
44
04
58
56
04
56
04
04
56
04
04
56
04
04
56
04
04
56
04
58
80
96
44
48
66
96
42
44
96
44
96
96
44
96
96
44
96
96
44
96
96
44
96
3
1
20
20
2
05
2
2
2
0
1
1,12
D industrial processes,
13,14
electronic applications.
0
MeOH
15–17
ing process to be studied.
0
0
0
18
2
E
E
3
CH CN
20
2
0
MeOH
CH CN
20
20
2
3
3
19–22
drawing end groups.
Here, we prepared several 9-an-
0
thraceneacrylic acid esters, arylethylenes carrying electron-
withdrawing end groups (Scheme 1), to study photochemical
E–Z isomerization process. All of the compounds prepared
underwent wavelength-dependent E-to-Z isomerization involv-
ing a charge-transfer or polar singlet excited state. Fluores-
cence studies carried out indicate the polar or chargetransfer
nature of the singlet excited state. Photochemical isomeriza-
tion induced by the triplet sensitizers was found to be Z-to-E in
all the compounds following quantum chain process. Photo-
chemical isomerization carried out in a micelle environment
highlights the restrictions imposed on the isomerization pro-
cess.
MeOH
20
20
20
20
20
20
20
20
4E
5E
CH CN
3
MeOH
CH CN
3
MeOH
CH CN
6
E
3
2
20
0
MeOH
Nitrogen bubbled 0.0005 M solutions were irradiated; for
28
> 400 nm, 450 W Hg lamp with filters; for > 300 nm,
50 W Hg lamp with Pyrex filter; for ~350 nm, Rayonet
4
Results and Discussion
RUL-3500 lamps; analysis by reverse phase HPLC.
Photoisomerization upon Direct Excitation and Triplet
Sensitization. All of the compounds 1E–6E (Scheme 1)
were synthesized and characterized by spectral means (experi-
mental section). Compounds 1E–6E were dissolved in a suit-
able solvent and irradiated using 450 W Hg lamp with filters
(> 400 nm) and also with RUL-3500 (~350 nm) in a Rayonet
reactor. The obtained results are given in Table 1. The isomer

2
488 Bull. Chem. Soc. Jpn., 75, No. 11 (2002)
E-Z Isomerization in 9-Anthraceneacrylic Esters
Scheme 1. Reagents and conditions: i) malonic acid, pyridine and piperidine at steam bath for 4 h, 125–130 °C for 1 h and at 180–
90 °C for 30 min; ii) 3,4-dihydropyran, CHCl , 0.01 mol SnCl ·2H O at r.t. for 24 h; iii) monoprotected diol, DCC, DMAP, dry
CH Cl , under N atmosphere for 3 h; iv) I /MeOH reflux for 5 h; v) DCC, DMAP, dry CH Cl , under N atmosphere for 3 h; vi)
hv, N bubbled and irradiated using 450 W Hg arc lamp with suitable filters (> 400 nm) for 45 min.
1
3
2
2
2
2
2
2
2
2
2
2
composition was monitored by HPLC. All of the compounds,
E–6E underwent very efficient E-to-Z isomerization upon di-
rect excitation using > 400 nm radiation (Table 1). The iso-
mer composition was found to be different under ~350 nm
in the region of 163–180 kJ/mol. The triplet sensitization stud-
ies conducted on 1E–6E were found to be ineffective and there
was no E- to-Z isomerization observed. The Z isomers of 1Z–
6Z were found to undergo efficient, almost complete one-way
conversion to the E isomer (Table 3). Triplet sensitized
isomerization studies establishes that the triplet energy of the
substrates are in the range of > 163 kJ/mol, and that it is effec-
tive in bringing Z-to-E conversion only.
1
(
RUL-3500; Rayonet reactor) and > 300 nm (450 W Hg lamp;
pyrex filter) irradiations (Table 1). The photoisomerization of
E was monitored at various time intervals (> 400 nm irradia-
1
tion), and the result is the accumulation of > 96% of the Z iso-
mer. These studies indicate that the E-to-Z selectivity is wave-
length dependent. The reported isomer composition also re-
flects the photostationary state composition under the given
photolytic conditions. Photochemical E–Z isomerization was
conducted in CTAB and SDS micellar environments. The pho-
tostationary state composition was 30:70 (E:Z) upon direct
excitation, (> 400 nm; Table 2) in a micellar environment.
The wavelength (> 400 nm) dependent E-to-Z selectivity no-
ticed in organic solvents (Table 1) is not observable in a micel-
lar environment (Table 2).
The quantum yields of the isomerizations were determined
for E-to-Z, Z-to-E upon direct excitation and triplet sensitized
Z-to-E (Table 4) in methanol solvent, and also for 1E-to-Z and
6E-to-Z. The quantum yield of isomerization upon direct exci-
tation is fairly fine, and represents that it is efficient. The quan-
tum yield of Z-to-E isomerization upon triplet sensitization is
interesting because the values are well above unity, which is
consistent with the one-way isomerization concept developed
2
7
earlier.
Absorption and Fluorescence Studies. Absorption and
fluorescence studies were conducted to understand the nature
of the excited state. Absorption spectra were recorded for all
of the compounds in various solvents, CTAB & SDS micelles.
The generated data are compiled in Table 5. The absorption
maximum did not change upon changing the medium (Table
Triplet sensitized reactions were planned so as to under-
stand and differentiate the triplet/singlet reactivities. The trip-
let sensitizers employed were visible absorbing dyes, and
could be selectively excited in the presence of substrates 1E–
6E. The triplet energy of the selected sensitizers (Table 3) fell

M. Janaki Ram Reddy et al.
Bull. Chem. Soc. Jpn., 75, No. 11 (2002) 2489
Table 2. Isomer Composition Upon Direct Excitation of 1E–
Table 4. Quantum Yield of Photoisomerization of 1E–6E
and 1Z–6Z
6
E in Micelles
Compound
Micelle
CTAB
λex/nm
E/%
Z/%
Compound
Φ
E Z
iso
Φ
Z E
iso
Φ
Z E
iso Triplet Sens.
1
2
3
4
5
6
E
E
E
E
E
E
> 400
300
> 400
300
> 400
300
> 400
300
> 400
300
> 400
300
> 400
300
> 400
300
> 400
300
> 400
300
> 400
300
> 400
300
22
55
26
52
24
56
25
55
23
54
22
56
26
58
24
54
27
55
26
54
22
58
23
57
78
45
74
48
76
44
75
45
77
46
78
44
74
42
76
46
73
45
74
46
78
42
77
43
>
1
2
3
4
5
6
1
0.21
0.22
0.21
0.22
0.22
0.23
0.11 (hexane)
0.14 (benzene)
0.12 (hexane)
0.16 (benzene)
0.22 1.64
0.23 1.82
0.23 1.56
0.24 1.66
0.25 1.72
0.26 1.86
SDS
>
CTAB
SDS
>
>
—
—
—
—
—
—
—
—
CTAB
SDS
>
6
>
Nitrogen bubbled 0.001 M methanol solutions with 0.001
M sensitizer were irradiated in a merry-go-round of QYR-
0 quantum yield reactor; the 366 nm line of the 200 W Hg
arc lamp was isolated to irradiate; analysis by reverse phase
HPLC.
CTAB
SDS
>
2
>
CTAB
SDS
>
The E isomer has broad absorption in the 340 to 400 nm re-
gion,. and the Z isomer has relatively structured absorption in
the same region (Figs. 1 & 2). Fluorescence was recorded at
room temperature for all of the compounds. The fluorescence
emission maxima and quantum yield of fluorescence data are
given in Table 5, and the fluorescence spectra for three com-
pounds are displayed in Figs. 3–5. The fluorescence emission
maximum showed a red shift of ~20 nm (Table 5) upon
changing the nonpolar solvent hexane to polar solvent acetoni-
trile/methanol/micelles. There was a decrease in the quantum
yield of fluorescence upon changing the nonpolar hexane sol-
vent to polar acetonitrile/methanol/micelles. The red shift ob-
served in the emission maxima and the decrease in the quan-
tum yield of the fluorescence upon changing the solvent polar-
ity throws light on the singlet excited state as being charge-
transfer or polar in nature. There was a slight increase in the
fluorescence quantum yield for all compounds in CTAB &
SDS micelles compare to polar solvents acetonitrile/methanol.
There was not much change observed in the fluorescence spec-
trum of Z isomers (Figs. 3–5) compared to E isomers.
>
CTAB
SDS
>
>
Nitrogen bubbled 0.001 M solutions were irradiated for 45
min; for > 400 nm, 450 W Hg lamp with filters; for >
00 nm, 450 W Hg lamp with pyrex filter; analysis by
reverse phase HPLC; the concentration of CTAB & SDS
was kept well above the corresponding CMCs.
2
8
3
Table 3. Isomer Composition Upon Triplet Sensitization of
1
Z–6Z, 1E and 6E
Com- Sensitizer
pound
λ
max/nm ET-Sens. E/%
Z/%
kJ/mol
~163 98
~180 98
~163 98
~180 98
~163 98
~180 98
~163 98
~180 98
~163 98
~180 98
~163 98
1Z
2Z
3Z
4Z
5Z
6Z
Rose Bengal 550
Eosin 515
Rose Bengal 550
Eosin 515
Rose Bengal 550
Eosin 515
Rose Bengal 550
Eosin 515
Rose Bengal 550
Eosin 515
Rose Bengal 550
Eosin 515
Rose Bengal 550
Eosin 515
Rose Bengal 550
Eosin 515
02
02
02
02
02
02
02
02
02
02
02
02
Photoisomerization and Nature of the Singlet Excited
State. Table 1 reveals that all of the compounds 1E–6E upon
direct excitation using > 400 nm radiation produced the ther-
modynamically less stable Z isomer > 96% (Scheme 2, reac-
tion. 1). The highly selective E-to-Z isomerization is attributed
to the higher light absorption capabilities of the E isomer under
30–32
the irradiation conditions.
This explanation becomes more
clear by saying that upon changing the wavelength of irradia-
tion, both isomers absorb light and give almost a 1:1 photosta-
tionary state mixture (Table 1; Scheme 2, reaction. 2; Fig. 1
and 2). The quantum yield of the isomerization data (Table 4)
also suggests that both E-to-Z and Z-to-E are equally efficient
processes from the singlet excited manifold. The E-to-Z
isomerization originates from the singlet excited state, since
the triplet excitation is ineffective in producing the Z isomer
from the E isomer. Triplet sensitization is effective in convert-
ing the Z isomer to the E isomer only (Scheme 2, reaction. 4;
Table 3). The quantum yield of isomerization from the triplet
~180 98
1
6
E
E
~163 No isomerization
~180 No isomerization
~163 No isomerization
~180 No isomerization
Nitrogen bubbled 0.001 M methanol solutions with 0.001 M
sensitizer were irradiated for 15 min using 450 W Hg lamp
with filters, > 500 nm; analysis by reverse phase HPLC.
5
), which informs that there is not much ground- state and me-
dium interaction.

2
490 Bull. Chem. Soc. Jpn., 75, No. 11 (2002)
E-Z Isomerization in 9-Anthraceneacrylic Esters
Table 5. Absorption and Fluorescence Data for 1E–6E and
Z, 3Z, 6Z
1
Compound
Solvent
λabs/nm
λfluo/nm
Φ
flu
1
E
Hexane
MeOH
CH CN
3
SDS
CTAB
Hexane
CH CN
3
Hexane
MeOH
3
CH CN
SDS
CTAB
Hexane
MeOH
3
CH CN
SDS
CTAB
Hexane
CH CN
3
Hexane
MeOH
3
CH CN
388
388
388
388
388
385
385
387
387
387
387
387
388
388
388
388
388
385
385
386
386
386
386
386
388
388
388
388
388
389
389
389
389
389
385
385
488
508
508
508
508
488
508
492
512
516
512
516
484
508
508
508
508
484
508
488
512
512
512
512
488
508
508
508
508
488
520
520
512
512
488
520
0.51
0.08
0.09
0.16
0.12
0.34
0.04
0.49
0.09
0.07
0.26
0.22
0.56
0.14
0.11
0.28
0.21
0.32
0.08
0.50
0.11
0.09
0.18
0.17
0.47
0.12
0.09
0.19
0.12
0.70
0.11
0.12
0.18
0.16
0.49
0.08
1
Z
2
E
3
E
3
Z
4
5
6
E
E
E
Scheme 2.
SDS
CTAB
Hexane
MeOH
CH CN
3
SDS
CTAB
Hexane
MeOH
3
CH CN
SDS
CTAB
Hexane
6
Z
Scheme 3.
CH
.00001 M Solutions were used for measuring the fluores-
cence at room Temperature; quantum yield of fluorescence
were determined using 9,10-diphenylanthracene (Φflu
3
CN
0
understand the nature of the singlet excited state. The UV–vis-
ible absorption data indicate that there is not much ground
state and medium interactions in all of the substrates (Table 5).
The red shift observed in the emission maxima (fluorescence
=
2
9
0
.9) as standard, experimental error ± 10%.
3
4
solvatochromism) for all of compounds 1E–6E (Table 5) by
changing the solvent polarity and solvent polarity dependent
quantum yield of E-to-Z photoisomerization indicates that the
singlet excited state has a considerable amount of charge-
state for all compounds was found to be higher than unity
3
3
(Table 4). This is consistent with an earlier observation that
the triplet state in anthrylethylenes induces a quantum chain
process leading to higher quantum-yield values. More inter-
estingly, the E-to-Z selectivity observed (Table 1; Scheme 2,
reaction. 1) for all compounds 1E–6E in the organic solvent
phase is not the case when a micellar (CTAB, SDS; Table 2;
Scheme 2, reaction. 3) medium was introduced. Although Z is
the preferred isomer (Scheme 2, reaction. 3), the % of Z isomer
formed was less (Scheme 2, reaction. 3; Table 2). The de-
crease in the selectivity of E-to-Z isomerization may be due to
restrictions imposed by the micellar environment, exerting a
hindrance for rotation of the double bond, or it may promote
the possible formation of a triplet state. UV–visible absorption
and fluorescence studies were carried out (Table 5) in order to
35–36
transfer or polar character,
and is responsible for the E-to-
Z photoisomerization. The very high Z isomer formation also
suggests that the charge-transfer or polar singlet excited state
3
7
may not undergo intersystem crossing to form a triplet state.
Mechanism. The proposed mechanism for photochemical
E–Z isomerization studies conducted for 1E–6E is depicted in
Scheme 3. The light absorption (> 400 nm) by the E sub-
strate, followed by structural changes in the molecule, leads to
the formation of a charge-transfer (CT) or polar singlet excited
state. The formation of a CT state was confirmed by fluores-
cence studies (Table 5). The thus-formed CT or polar excited
state would undergo rotation around the double bond to give

M. Janaki Ram Reddy et al.
Bull. Chem. Soc. Jpn., 75, No. 11 (2002) 2491
−
5
Fig. 1. UV-visible absorption spectra of 1E and 1Z in hexane, at 10 M.
−
5
Fig. 2. UV-visible absorption spectra of 6E and 6Z in hexane, at 10 M.
−
5
Fig. 3. Fluorescence and fluorescence excitation spectra of 1E (——) and 1Z (≥≥) in hexane, at 10 M.
1
9,27,33
the Z isomer. The formation of a triplet state from the CT or
polar state may not be possible, since very high E-to-Z selec-
tivity was observed, and the E triplet did not give the Z iso-
mer.
The Z isomer was found to undergo efficient one-
3
7
way Z-to-E isomerization from the triplet state.

2
492 Bull. Chem. Soc. Jpn., 75, No. 11 (2002)
E-Z Isomerization in 9-Anthraceneacrylic Esters
−
5
Fig. 4. Fluorescence and fluorescence excitation spectra of 3E (——) and 3Z (≥≥) in hexane, at 10 M.
−
5
Fig. 5. Fluorescence and fluorescence excitation spectra of 6E (——) and 6Z (≥≥) in hexane, at 10 M.
wavelength of irradiation to > 300 nm or ~350 nm led to the
Conclusions
photo stationary state equilibration of two isomers. Triplet
In conclusion, we synthesized several (1E–6E) 9-anthrace-
sensitization produces only Z-to-E isomerization. The higher
quantum yields observed in the triplet induced isomerization
process is indicative that quantum chain isomerization is in op-
eration. Fluorescence studies carried out on compounds 1E–
neacrylic esters to study photochemical E–Z isomerization.
All of compounds 1E–6E underwent selective E-to-Z isomer-
ization upon direct excitation (> 400 nm). Changing the

M. Janaki Ram Reddy et al.
E showed that a charge-transfer or polar excited state is in-
volved in the direct excitation reactions. Photochemical
isomerization studies carried out in a micellar environment are
interesting.
Bull. Chem. Soc. Jpn., 75, No. 11 (2002) 2493
24
6
Preparation of Monoprotected Diols.
mmol) and 3,4 di-hydropyran (100 mmol) were stirred in solvent
CHCl (200 mL), followed by the addition of 0.001 mole
1 mole%) of SnCl ·2H O at room temperature for 24 hours. The
layer was separated by decantation and concentrated under
The diol (100
3
(
2
2
CHCl
3
reduced pressure. The product was separated by column chroma-
tography over silica gel while eluting with pet ether for the dipro-
tected tetra hydro pyrenyl ether (yield 20–25%) and pet ether,
EtOAc (80:20) for a monoprotected diol yield of 75–80%.
Experimental
General Procedures. A Perkin-Elmer Lambda-2 UV-visible
spectrometer was used to obtain the absorption spectra. A SPEX
Fluorolog 0.22 m fluorimeter was used for fluorescence measure-
ments. Mass spectra were recorded on a VG Micro Mass 7070H
instrument. Proton nuclear magnetic resonance ( H NMR) spec-
3
tra were recorded on a FT-200 MHz instrument in a CDCl sol-
vent. A Shimadzu LC-8 HPLC system with a CR-8 integrator was
used for HPLC analysis. An Applied Photo Physics QYR-20
Quantum Yield Reactor coupled with a 200 W Hg lamp was used
to determine the quantum yields. All other chemicals were pur-
chased locally and also from Aldrich/Fluka.
25
Esterification of 9-Anthraceneacrylic Acid.
After a mix-
ture of 9-anthraceneacrylic acid (10 mmol), dichloromethane (dry;
10 mL) 2 drops of dry DMF, DMAP (30–90 mg) and monopro-
tected diol (20–30 mmol) was cooled to 0 °C, DCC (10 mmol)
was added and the mixture was stirred at 0 °C for 5 min and then
3h at rt. The filtered and dichloromethane solution was washed
1
thrice with 0.5 M HCl, then with NaHCO
Na SO . The solvent was removed and the residue was purified by
silica-gel column chromatography using 1:1 CH Cl /Hexane to
100% CH Cl to obtain protected ester in 80% yield.
Deprotection of 9-Anthraceneacrylic Acid Protected Ester.
3
solution and dried over
2
4
2
2
Photolysis. A Rayonet reactor equipped with RUL-3500
~350 nm) lamps and a 450 W medium pressure Hg arc lamp
2
2
26
(
along with suitable filters were used for irradiation. All reactions
A mixture of protected 9-anthraceneacrylic ester (10 mmol),
methanol (20 mL) and iodine (0.1 mmol) was heated under reflux
for 5 h. After methanol was removed, the residue was taken in
ethyl acetate and washed with hypo, brine and water and dried
over Na SO . The solvent was removed and the product was puri-
2 4
fied by silica-gel column chromatography using hexane/EtOAc
(50:50) to obtain 9-anthraceneacrylic ester, yield 75%.
were monitored by HPLC using a C-18 reverse-phase 5µ, 0.5 cm/
2
5 cm column. In a typical experiment 10 mL of a 0.0005 M N
2
bubbled solution of 1E–6E was used for irradiation. After irradia-
tion the products were characterized by comparing with authentic
samples. Triplet sensitized reactions were carried out using a mix-
ture of a sensitizer (0.001 M) and a substrate (0.001 M) in a sol-
vent (N
2
bubbled), which was irradiated using a 450 W Hg lamp
The above procedures were repeated to synthesize other deriva-
tives (Scheme 1). The cholesterol derivative 6E was synthesized
by adopting an esterification procedure. Z isomers were prepared
(1Z–6Z) by the preparative photoisomerization procedure (experi-
mental section, photolysis) and isolated by silica-gel column chro-
with suitable filters (> 500 nm).
Preparative photoisomerization was carried out using 100 mg
of 1E–6E in 150 ml methanol or acetonitrile solvent, bubbled ni-
trogen and irradiated using a 450 W Hg lamp with suitable filters
1
(> 400 nm) for 45 min; the reaction was monitored by HPLC and
matography. The product was characterized by H-NMR and oth-
the Z isomer was isolated by silica-gel column chromatography.
The product was characterized by H NMR and other spectral
er spectral data. The spectral data for 1E–6E & 1Z–6Z are given
below.
1
data.
3-Hydroxypropyl (E)-9-Anthraceneprop-2-enoate (1E). A
Semisolid; H NMR (CDCl ) δ 2.1 (m, 2H), 3.8 (t, 2H), 4.5 (t,
3
2H), 6.4–6.5 (d, 1H, J = 16.5 Hz), 7.4–7.6 (m, 4H), 8.05 (m, 2H),
1
Fluorescence: A SPEX-Fluorolog fluorimeter equipped with a
4
50 W Xenon lamp was used to generate fluorescence data. Dry
solvents were used, identical conditions were employed for all of
the fluorescence measurements and 9,10-diphenyl anthracene was
used as fluorescence standard (Φflu = 0.9) for determining the
quantum yield of the fluorescence. The slit widths were 2 × 2 ×
8.2–8.3 (m, 2H), 8.4–8.5 (s, 1H), 8.7 (d, 1H, J = 16.5 Hz); MS
+
306 (M ), 231 202, 99; HRMS m/z calculated for C20
306.125595, found 306.125634; UV 388 nm (ε 6400).
18 3
H O
3-Hydroxypropyl (Z)-9-Anthraceneprop-2-enoate (1Z).
A
1
2
× 2 and the emission spectral range was 400–700 nm. All oper-
3
semisolid; H NMR (CDCl ) δ 1.15 (m, 2H), 2.7 (t, 2H), 3.8 (t,
ations were carried out at room temperature.
Preparation of 9-Anthraceneacrylic Acid.
2H), 6.65 (d, 1H, J = 14.28 Hz), 7.4–7.5 (m, 4H), 8 (m, 4H), 8.4
2
3
+
A mixture of
(s, 1H), 7.8 (d, 1H, J = 14.28 Hz); Mass: 306 (M ), 231, 202, 99;
2
.06 g 9-Antraldehyde, 1.4 g of malonic acid, 0.5 mL of piperdine
UV 385 nm (ε 5500).
and 3 ml of pyridine was heated on a steam bath for four hours;
the solution was then refluxed for one hour in an oil-bath at 125–
4-Hydroxybutyl (E)-9-Anthraceneprop-2-enoate (2E).
A
1
semisolid; H NMR (CDCl ) δ 1.7–2 (m, 4H), 3.8 (t, 2H), 4.4 (t,
3
1
35 °C. The mixture was cooled, diluted with 20 mL of water and
2H), 6.4–6.5 (d, 1H, J = 15 Hz), 7.4–7.6 (m, 4H), 8–8.1 (m, 2H),
8.2–8.35 (m, 2H), 8.5 (s, 1H), 8.6–8.8 (d, 1H, J = 15 Hz); MS m/z
soon solidified. The orange solid weighed 3.08 g. When dry and
it began to melt with decomposition at about 145 °C, it evidently
consisted rarely of the substituted malonicacid. The material was
heated for 30 min. at 180–190 °C to eliminate any carbon dioxide.
The dark-red melt solidified upon cooling, and was purified by re-
crystalization from 12 mL of chlorobenzene containing 0.5 mL of
glacial acetic acid. 9-Anthraceneacrylic acid formed as bright-yel-
low needles (mp 235.5–237.5 °C, yields 2.05 g (82.6%)). A sec-
ond recrystalization gave a first crop of 1.80 g, mp 246–247 °C.
+
320 (M ), 248, 231, 203, 143, 101; HRMS m/z calculated for
C
21
H
20
O
3
320.141245, found 320.142461; UV 387 nm (ε 6400).
4-Hydroxybutyl (Z)-9-Anthraceneprop-2-enoate (2Z).
semisolid; H NMR (CDCl ) δ 0.5–0.7 (m, 2H), 0.7–0.9 (m, 2H),
A
1
3
3–3.2 (t, 2H), 3.5–3.7 (t, 2H), 6.5–6.7 (d, 1H, J = 14.3 Hz), 7.4–
7.6 (m, 4H), 7.9–8.1 (m, 4H), 8.4 (s, 1H), 7.8–7.9 (d, 1H, J = 14.3
+
Hz); MS m/z 320 (M ), 248, 231, 203, 143, 101; UV 385 nm
(ε 5500).
1
Spectral data: H-NMR δ 6.3–6.45 (d, 1H, J = 15.4 Hz), 7.4–7.6
5-Hydroxypentyl (E)-9-Anthraceneprop-2-enoate (3E).
A
1
(
8
m, 4H), 7.9–8.1 (m, 2H), 8.2–8.35 (m, 2H), 8.4–8.45 (s, H), 8.5–
.65 (d, 1H, J = 15.4 Hz); MS m/z 248 (M ), 203, 101, 83.
semisolid; H NMR (CDCl
3
) δ 1.4–1.9 (m, 6H), 3.5–3.7 (t, 2H),
+
4.2–4.4 (t, 2H), 6.3–6.5 (d, 1H, J = 16 Hz), 7.35–7.55 (m, 4H),

2
494 Bull. Chem. Soc. Jpn., 75, No. 11 (2002)
E-Z Isomerization in 9-Anthraceneacrylic Esters
(1980), vol. 3, p. 5.
7
=
.9–8 (m, 2H), 8.1–8.3 (m, 2H), 8.3–8.4 (s, 1H), 8.5–8.7 (d, 1H, J
+
16 Hz); MS m/z 334 (M ), 248, 231,204, 99; HRMS m/z calcu-
2
M. T. Allen and D. G. Whitten, Chem. Rev., 89, 1691
lated for C22
ε 6100).
-Hydroxypentyl (Z)-9-Anthraceneprop-2-enoate (3Z).
H
22
O
3
334.156895, found 334.158432; UV 388 nm
(1989).
(
3
4
5
6
D. H. Waldeck, Chem. Rev., 91, 415 (1991).
H. Garner and H. J. Kuhn, Adv. Photochem., 19, 1 (1995).
L. Zechmeister, Experientia, 10, 1 (1954).
5
A
1
semisolid; H NMR (CDCl
–1.2 (m, 2H), 3.15–3.3 (t, 2H), 3.5–3.7 (m, 2H), 6.5–6.65 (d, 1H,
J = 10.7 Hz), 7.4–7.55 (m, 4H), 7.7–7.8 (m, 4H), 8.45 (s, 1H),
3
) δ 0.4–0.5 (m, 2H), 0.7–0.85 (m, 2H),
1
J. Saltiel and Y. P. Sun, in “Photochromism: Molecules,
and Systems,” ed by H. Durr and H. Bonos-Laurent, Elsevier,
Amsterdam (1990), p. 64.
+
7
9
.7–7.8 (d, 1H, J = 10.7 Hz); MS m/z 334 (M ), 248, 231,204,
9; UV 385 nm (ε 5400).
7
G. Orlando, F. Zerbetto, and M. Zgierski, Chem. Rev., 91,
6
-Hydroxyhexyl (E)-9-Anthraceneprop-2-enoate (4E).
) δ 1.2–1.9 (m, 8H), 3.6–3.75 (t, 2H),
.3–4.4 (t, 2H), 6.3–6.5 (d, 1H, J = 15.4 Hz), 7.4–7.6 (m, 4H),
.9–8.1 (m, 2H), 8.3–8.3 (m, 2H), 8.4–8.5 (s, 1H), 8.5–8.7 (d, 1H,
J = 15.4 Hz); MS 348 (M ), 231, 203, and 99; HRMS m/z calcu-
A
867 (1991).
1
semisolid; H NMR (CDCl
4
7
3
8
(1984).
9
R. S. H. Liu, and A. E. Asato, Tetrahedron, 40, 1931
M. Mouseron-Canet, Methods Enzymol., 58, 591 (1971).
+
10 R. S. H. Liu and Y. Schichida, in “Photochemistry in Orga-
nized and Constrained Media,” ed by Ramamurthy, VCH Publish-
ers (1991), Chapter 18, p. 18.
11 A. M. Braun, M. J. Maurette, and E. Oliveror, “Photo-
chemical Technology,” Wiley (1991), Chapter 12, p. 500.
12 Kirk-Other Encyclopedia of Chemical Technology, 4th ed,
Wiley (1996), vol. 18, p. 799.
13 “Photochromism: Molecules and Systems,” ed by H. Durr
and H. Bous-Laurent, Elsevier, Amsterdam (1990).
14 B. L. Feringa, Tetrahedron, 49, 8267 (1993).
15 F. D. Lewis, and R. S. Kalgutkar, J. Phys. Chem. A, 105,
285 (2001).
lated for C23
ε 6200).
-Hydroxyhexyl (Z)-9-Anthraceneprop-2-enoate (4Z).
24 3
H O 348.172545, found 348.171221; UV 386 nm
(
6
A
1
Semisolid; H NMR (CDCl ) δ 0.4–0.8 (m, 8H), 3.4–3.5 (t, 2H),
3
3
7
3
.6–3.7 (m, 2H), 6.6–6.7 (d, 1H, J = 12.5 Hz), 7.4–7.6 (m, 4H),
.7–7.8 (d, 1H, J = 10.7 Hz), 8–8.1 (m, 4H), 8.4 (s, 1H); MS m/z
+
48 (M ), 231, 203, and 99; UV 385 nm (ε 5300).
1
0-Hydroxydecyl (E)-9-Anthraceneprop-2-enoate (5E).
A
1
solid mp 121 °C; H NMR (CDCl ) δ 1.2–1.9 (m, 16H), 3.6–3.7 (t,
3
2
4
1
H), 4.3–4.4 (t, 2H), 6.4–6.55 (d, 1H, J = 16.3 Hz), 7.47–7.65 (m,
H), 8–8.15 (m, 2H), 8.22–8.35 (m, 2H), 8.5 (s, 1H), 8.6–8.75 (d,
H, J = 16.3 Hz), MS 404 (M ), 249, 232, 204, 55; HRMS m/z
+
16 K. L. Wieners and J. F. Kaufman, J. Phys. Chem. A, 105,
823 (2001).
calculated for C27
H
32
O
3
404.235788 found 404.235788; UV 388
nm (ε 6700).
17 P. Rademaches, A. L. Marzinzik, K. Kowski, and M. E.
Weiss, Eur. J. Org. Chem., 1, 121 (2001).
18 T. Arai and K. Tokumaru, Adv. Photochem., 20, 1 (1995).
19 K. Mani Bushan, G. Venugopal Rao, T. Soujanya, V.
Jayathirtha Rao, S. Saha, and A. Samantha, J. Org. Chem., 66, 681
(2001).
20 F. D. Lewis and J. M. Denari, J. Photochem. Photobiol. A,
105, 151 (1996).
21 H. Tanaka, K. Honda, and N. Suzuki, J. Chem. Soc. Chem.
Commun., 1977, 506.
22 V. Jayathirtha Rao, in “Organic Photochemistry: Molecular
& Supramolecular Photochemistry,” ed by, V. Ramamurthy, and
K. Schanze, Marcel Dekker, New York (1999), vol. 3, Chapter ꢁ,
p. 169.
23 C. H. Davis, and M. Karmack, J. Org. Chem., 12, 76
(1947).
1
0-Hydroxydecyl (Z)-9-Anthraceneprop-2-enoate (5Z).
A
1
solid mp 110 °C ; H NMR (CDCl
3
) δ 0.1–1.85 (m, 18H), 2.4–2.7
(
(
(
t, 2H), 6.5–6.7 (d, 1H, J = 14.28 Hz), 7.4–7.55 (m, 4H), 7.8–7.9
d, 1H, J = 14.28 Hz), 7.9–8.15 (m, 4H), 8.4 (s, 1H); MS 404
+
M ), 249, 232, 204, 55; UV 385 nm (ε 5800).
Cholest-5-en-3β-yl (E)-9-Anthraceneprop-2-enoate (6E).
1
A solid mp 163.5 °C ; H NMR (CDCl
3
) δ 0.6–2.1 (m, 39 Hs),
2
.4–2.55 (m, 2H), 3.1–3.3 (m, H), 4.75–4.95 (m, 2H), 5.4–5.5 (m,
H), 6.3–6.45 (d, 1H, J = 15.78 Hz), 7.4–7.6 (m, 4H), 7.9–8.05 (m,
H), 8.2–8.3 (m, 2H), 8.4 (s, 1H), 8.55–8.7 (d, 1H, J = 15.78 Hz);
2
+
FAB MS m/z 617 (M ), 369, 281, 245, 231, 202; UV 389 nm
(ε 6900).
Cholest-5-en-3β-yl (Z)-9-Anthraceneprop-2-enoate (6Z).
1
A solid mp 154 °C; H NMR (CDCl
3
) δ 0.4–1.9 (m, 42 Hs), 4.1–
4
7
.2 (m, H), 5.1 (m, 2H), 6.6 (d, 1H, J = 12.3 Hz), 7.4–7.5 (m, 4H),
.8 (d, 1H, J = 12.3 Hz), 8–8.1 (m, 4H), 8.45 (s, 1H); FAB MS
24 J. Davies, U. T. Bhalerao, and B. V. Rao, Synth. Commun.,
29, 1679 (1999).
+
m/z 617 (M ), 369, 281, 245, 231, 202; UV 385 nm (ε 5700).
2
5
B. Neiser, and W. Steglich, Angew. Chem. Intl. Ed. Eng.,
The Department of Science & Technology, New Delhi is ac-
knowledged for financial support. US and KS thank Universi-
ty Grant Commission, New Delhi and Council of Scientific &
Industrial Research, New Delhi for Research Fellowships. We
thank Director IICT and Head Division Org. ꢀ for encouraging
support in these investigations. IICT Communication No.
17, 522 (1978).
26 J. S. Yadav, and B. V. S. Reddy, Chem. Lett. 1999, 857.
2
7
T. Arai, T. Karatsu, H. Sakuragi, and K. Tokumary, Tetra-
hedron Lett., 24, 2873 (1983).
J. C. Scaiano, “Hand Book of Organic Photochemistry,”
CRC press, Boca Raton, FL (1989).
2
8
2
9
A. Maciejewski and R. P. Steer, J. Photochem, 35, 59
0
10913.
(
1986).
3
0
N. J. Turro and V. Ramamurthy, Chem. Rev., 78, 125
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