Synthesis, properties and singlet oxygen generation of thiazolidinone double bond linked porphyrin at meso and β-position

Article abstract of DOI:10.1039/c6ra03489f

Meso and β-substituted free base and zinc metallated thiazolidinone-porphyrin conjugates were synthesized by one pot four component Knoevenagel condensation by utilizing substituted amines, carbon disulfide, ethyl chloroacetate and porphyrin aldehydes. These newly synthesized conjugates were characterized by IR, ¹H NMR, ¹³C NMR, UV-Vis, fluorescence and HRMS spectroscopy. The singlet oxygen generation behaviors of these porphyrin conjugates were studied and it was observed that these porphyrin conjugates followed type II singlet oxygen. Fluorescence and singlet oxygen quantum yields among meso-substituted (mono-, di, tetra) and β-substituted conjugates were examined. The photocatalytic photooxidation of naphthols and furan by using these new organic photocatalysts were further analysed and it was observed that meso-tetra substituted (Zn3a) and β-substituted (Zn6a) porphyrins are much efficient for generation of singlet oxygen and for photocatalytic photooxidation.

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PAPER
Synthesis, properties and singlet oxygen generation of thiazolidinone
double bond linked porphyrin at meso and β-position†
Sohail Ahmad, Kumar Karitkey Yadav, Uma Narang, Soumee Bhattacharya, Sarangthem Joychandra
Singh and S. M. S. Chauhan*
5
Received (in XXX, XXX) Xth XXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX
DOI: 10.1039/b000000x
Meso and βꢀsubstituted free base and zinc metalleted thiazolidinoneꢀporphyrin conjugates were
synthesized by one pot four component Knoevenagel condensation by utilizing substituted amines, carbon
disulfide, ethyl chloroacetate and porphyrin aldehydes. These newly synthesized conjugates were
1
13
1
0
characterized by IR., H NMR, C NMR, UVꢀVis, fluorescence and HRMS spectroscopy. The singlet
oxygen generation behaviors of these porphyrin conjugates were studied and it was observed that these
porphyrin conjugates followed type II singlet oxygen. Fluorescence and singlet oxygen quantum yields
among mesoꢀsubstituted (monoꢀ, di, tetra) and βꢀsubstituted conjugates were examined. The
photocatalytic photooxidation of naphthols and furan by using these new organic photocatalysts were
further analysed and it was observed that that mesoꢀtetra substituted (Zn3a) and βꢀsubstituted (Zn6a)
porphyrins are much efficient for generation of singlet oxygen and for photocatalytic photooxidation.
1
5
Introduction
Therefore the synthesis of newer porphyrins, with high singlet
oxygen efficiency, photo stability and better solubility is quite
challenging for their applications in PDT and photooxygenation
reactions.
1
Singlet oxygen ( O ) is one of the most reactive oxygen species
(
2
ROS) and holds a prominent role in various chemical and
biological processes like medical sciences, photodynamic therapy
waste water treatment and
reactions. The extensive applications of O , lead to the
development of a series of photosensitizers including xanthene,
rosebengal, methylene blue and porphyrin derivatives.
Recently, the porphyrin derivatives have gained a considerable
interest due to the presence of their unique photochemical and
photophysical properties. Among the different classes of the
2
2
3
3
0
5
0
5
5
5
6
6
0
5
0
5
Rhodanine (thiazolidinone) derivatives have been widely
1,2
3
(PDT),
photooxygenation
10
studied as antibacterial, antiviral, antidiabetic agents. A variety
4
1
2
of rhodanineꢀporphyrin have been designed and synthesized to
modify their binding ability toward proteins and demonstrating
4
b,5
their importance as porphyrinꢀbase photosensitizers and
11
photocleaving
agents.
Recently,
rhodanineꢀporphyrin
substituted with acid group were found to be good protein probes
for proteins as well as their binding affinities and showed
6
PDT drugs, only porphyrin derivatives are approved by food and
11a
promising fluorescence and singlet oxygen quantum yields.
drug
administration
(FDA)
for
human
treatment.
Rhodanine now become a preferable choice in dyes and solar cell
to tune spectroscopic and electrochemical properties by their
Tetraphenylporphyrin (TPP) has been effectively used for the
photooxygenation reactions but it possesses certain disadvantages
such as poor solubility, low singlet oxygen generation efficiency
and photodegradation which limit its biological and
photooxygenation applications. In porphyrins, the increase in
generation of singlet oxygen has been attributed to the high
intersystem crossing efficiency and is improved either by
substitution or metal ion incorporation. Moreover, porphyrins
associated with electronꢀdonor or electronꢀacceptor moieties
through conjugated system led to the promising PDT results.
12
involvement as electron donor/acceptor agent.
Herein, we report a new series of meso and βꢀsubstituted
thiazolidinone porphyrins complexes and investigated the effect
of substitution and zinc atom insertion on their intersystem
crossing efficiency. The results showed that thiazolidinoneꢀ
porphyrin conjugates Zn6a and Zn3a exhibit better solubility in
aqueous methanolic medium and quantitative yields of singlet
oxygen, which makes them an ideal sensitizer for applications in
photodynamic therapy and green photooxygenation processes.
7
8
9
1
4
4
0
5
Bioꢀorganic Research Laboratory, Department of Chemistry, University
of Delhi, Delhiꢀ110 007, India. Fax: 91ꢀ11ꢀ27666845; Tel. 91ꢀ11ꢀ
7666845, 91ꢀ9871969266; Eꢀmail: smschauhan@chemistry.du.ac.in
Electronic Supplementary Information (ESI) available: H and
NMR spectra of all new compounds.
7
0
Results and discussion
2
†
Synthesis of the double bond linked mesoꢀtetraꢀsubstituted
porphyrin thiazolidinone conjugate 3a was achieved in 36% yield
by fourꢀcomponent Knoevenagel condensation of 5,10,15,20ꢀ
1
13
C
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DOI: 10.1039/C6RA03489F
tetrakis(4’ꢀformylphenyl)porphyrin (1a), benzylamine (2a), ethyl
The βꢀfused porphyrin thiazolidinone conjugates (6a-c) were
chloroacetate and carbon disulfide in the presence of a catalytic
prepared by condensation of one equivalent of 2ꢀformylꢀ
amount of triethylamine (TEA) in tetrahydrofuran (THF) at room 35 5,10,15,20ꢀtetra(4’’ꢀmethylphenyl)porphyrin (1d) with one
temperature for 2 hours then followed by 85 °C for 4 hours
(Scheme 1). The product was purified by column
chromatography on activated neutral aluminum oxide using
equivalents of ethyl chloroacetate and corresponding amine in the
5
0
5
0
5
0
presence of CS and triethylamine using THF as a solvent at 85
2
°C for 12 hours. The conjugate were purified by silica gel column
chromatography to afford brown solids 6a in 15%, 6b in 11% and
CHCl as an eluent. The same reaction with allylamine (2b) and
3
methylamine (2c) gave 3ꢀallylꢀ2ꢀthioxoꢀthiazolidinꢀ4ꢀone (3b) 40 6c in 27% yields respectively. The appearance of vinyl proton at
1
and
3ꢀmethylꢀ2ꢀthioxoꢀthiazolidinꢀ4ꢀone
(3c)
porphyrin
about δ 7.47 ppm ppm as a sharp singlet in the H NMR spectra
and a corresponding m/z peak in the mass spectra confirmed the
formation of 6a-c conjugates.
1
1
2
2
3
conjugates in 28% and 36% yield respectively. While, the
synthesis of mesoꢀdi and mono substituted thiazolidinone linked
porphyrins 4a-c and 5a-c were achieved by using 5,15ꢀdi(4’ꢀ
All the free base thiazolidinoneꢀporphyrin were transformed to
formylphenyl)ꢀ10,20ꢀdi(4’’ꢀmethylphenyl)porphyrin (1b) and 5ꢀ 45 corresponding zinc complexes in 91ꢀ83% yield by using three
(4’ꢀformylphenyl)ꢀ10,15,20ꢀtri(4’’ꢀmethylphenyl)porphyrin (1c)
equivalent of Zn(OAc)2 in CHCl ꢀmethanol solution. Among
3
respectively with primary amine, ethyl chloroacetate and carbon
these compounds, free base thiazolidinoneꢀporphyrin showed
solubility in common organic solvents like chloroform, methanol,
and dimethyl sulfoxide (DMSO), whereas zinc complexes
disulfide (CS ) in THF. The thiazolidinone conjugated newer
2
porphyrins (3, 4 and 5) were well characterized by NMR, UVꢀ
Visible, infrared (IR), elemental analysis and mass spectrometry 50 showed good solubility in both organic solvents as well as in the
and spectral data were in full agreement with the proposed
structures. The infrared absorption spectra of these thiazolidinone
conjugated porphyrins (3-5) exhibited a characteristic C=O
aqueous methanolic media.
The absorption spectra of free base conjugates and their
corresponding zinc complexes are given in table 1. On comparing
the electronic absorption spectra of mono substituted (5a), diꢀ
ꢀ
1
stretching band at 1699ꢀ1731 cm and the C=S stretching
ꢀ
1
1
vibration in the region of 1290ꢀ1092 cm . In H NMR spectra, a 55 substituted (4a) and tetraꢀsubstituted (3a) conjugates, it was
singlet at δ ꢀ2.8 ppm was assigned for the internal NH protons of
porphyrins and a singlet in aromatic region at δ 8.61ꢀ8.92 ppm
was the characteristic signal for βꢀpyrrolic protons. Further, the
presence of a singlet around δ 8.02 ppm was characteristic for
observed that the broadeness and red shiftness of soret and Q
band increases with the increase of thiazolidinone moiety on the
porphyrin ring (ESI) and followed the order of 3a>4a >5a.
Porphyrin conjugate 3a showed maximum red shifting of 17 nm
vinylic
CH=Thiazolidinone in
CH
proton
coressponding
NMR spectra, confirmed the
to
Porphyrin– 60 from simple TPP. When it was compared on the basis of the
1
H
nature of Nꢀalkylation among tetraꢀsubstituted porphyrin, the
shifting of soret band followed the order of 3a>3b>3c>TPP. Thus
the introduction of thiazolidinone moiety to porphyrin ring
greatly changed the energy of singlet excited state. While red
65 shift in the absorption spectra can be induced by the structural
distortion of porphyrin πꢀsystem as well as by electronic effect of
thiazolidinone
attachment of thiazolidinone moiety with porphyrins.
X1
Z
S
NHN
NHN
Cl
O
R
X4
X2
+
C
S
+
Triethylamine
+
NH2
O
THF, rt ꢀ 85 °C, 6h
X3
The free base βꢀsubstituted porphyrin (6a) showed different
electronic absorption spectrum than mesoꢀsubstituted porphyrins
70 (ESI) and appeared as very broad soret and Q bands. The UV–
Visible spectra of 6a showed splitting of soret band at 433 and
1
1
1
1
a : X1=X2=X3=X4= CHO, Z= H
R: 2a = C6H5CH2.
2
b = CH2=CHCH2
c = CH3
b : X1=X3= CHO, X2=X4= Me, Z= H
2
c : X1 = CHO, X2=X3=X4= Me, Z= H
d : X1=X2=X3=X4= H, Z= CHO
4
56 nm, while Q bands appeared at 528, 580, 615 and 667 nm.
R
N
R
N
S
O
S
O
Further the zinc metallated βꢀporphyrin Zn6a did not show the
splitting of soret band and appeared at 466 nm along with the Q
bands at 564, 614 nm (ESI). The βꢀsubstituted porphyrins 6a and
Zn6a contains the direct involvement of conjugation of
thiazolidinone with the 18πꢀmolecular system of porphyrin ring,
resulting in the substantial perturbation of the photophysical and
S
S
Me
S
7
5
S
N R
N
N
N
N
N
N
N
N
N
N
O
Me
M
M
Me Me
M
O
Me
N
N
R N
S
S
S
S
S
9
electrochemical properties of the porphyrin. This perturbation
O
S
O
N
R
S
O
S
N
R
N
R
80
can be mainly ascribed to the conjugation of πꢀorbitals from both
the linker and the pyrrolic ring which may induce some charge
transfer character to porphyrin π→π* transitions that are no
longer totally centred on the porphyrin ring.
The emission spectra of the 3a (671 and 734 nm) in methanol
85 are quite broadened and redꢀshifted compared to 3b (666 and 725
nm) and 3c (660 and 722 nm), table 1 (ESI). The red shifts in
porphyrins suggests that there is a increment in the πꢀconjugation
of these molecules which results in the reduction of the energy
gap between highest occupied molecular orbital (HOMO) and
3a-c ; M= H2
4a-c ; M= H2
Zn4a-c ; M= Zn
5a-c ; M= H2
Zn3a-c ; M= Zn
Zn5a-c ; M= Zn
13
Me
S
S
N
R
6 5 2
R = C H CH
O
N
N
N
N
Me
M
= CH2=CHCH2
CH3
Me
=
6
a-c ; M= H2
Zn6a-c ; M= Zn
Me
Scheme 1 Synthesis of Porphyrinꢀthiazolidinone conjugates.
14
90
lowest unoccupied molecular orbital (LUMO). Further the
2
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emission spectrum of βꢀsubstituted porphyrin 6a exhibit very
broad emission at 701 and 753 nm on excitation at 440 nm while
the corresponding zinc complex Zn6a showed good emission
peak at 706 nm.
and DPiBF was irradiated with a 200 W mercury lamp over a
time period of 0−60 min. The peak corresponding to DPiBF
showed decrease in absorbance in UVꢀVis spectra. The singlet
50 oxygen quantum yields were estimated by plotting the depletion
in absorbance of DPiBF against the irradiation time using
5,10,15,20ꢀtetraphenyl porphyrin zinc (ZnTPP) as a reference.
5
The fluorescence quantum yields (Φ ) of thiazolidinoneꢀ
f
porphyrin conjugates were examined from the emission and
9
,15
absorption spectra by a comparative method
(Table 1). From
Zn6a (0.89±0.02) and Zn3a (0.83±0.03) showed larger value of
1
the results, it is observed that the quantum yields are considerably
O quantum yield, as compared to other zinc thiazolidinoneꢀ
2
reduced on attachment of thiazolidinone moiety at meso and βꢀ 55 porphyrin conjugates (Table 1). The di and mono substituted zinc
1
1
2
2
3
3
4
0
5
0
5
0
5
0
positions of porphyrins. The reasons behind the reduced
fluorescence quantum yields are the enhanced nonꢀradiative
decay rates of the internal conversion and/or intersystem
complexes (Zn4a and Zn5a) showed value of 0.78±0.03 and
0.72±0.03 respectively.
Table 2 Photooxidation of naphthols (7a-c) and furan (7d) with
15,16
a
crossing.
Thiazolidinone substituents are mainly responsible
Zn6a
for the enhancement in intersystem crossing rates, thus causing
reduced fluorescence quantum yields. Free base porphyrin
showed high fluorescence quantum yields (Φ ) whereas the
f
corresponding zinc complex showed decrease in fluorescence
quantum yields (Φ ). The fluorescence quantum yields of
f
different tetra substituted zinc conjugates followed the order of
Zn3c (Φ = 0.031) > Zn3b (Φ = 0.028) > Zn3a (Φ = 0.023) and
f
f
f
among mono, di and tetra substituted zinc conjugates followed
the order of Zn5a (Φ = 0.023) > Zn4a (Φ = 0.027) > Zn3a (Φ
f
f
f
=
0.023). The βꢀsubstituted porphyrin conjugate Zn6a showed
much lower fluorescence quantum yields (Φ = 0.015) compared
f
to other thiazolidinoneꢀporphyrin conjugates.
An EPR spin trapping technique was used for the
identification of reactive oxygen species (ROS). The oxygen
saturated acetonitrile solution of 3a (0.1 mM) and 2,2,6,6ꢀ
tetrmethylpiperidine (TEMP) (50 mM) were irradiated with a 355
nm laser, and a threeꢀline EPR spectrum with equal intensity and
a hyperfine coupling constant of aN = 15.9 G was observed,
60
a
Reaction conditions: substrate (1 equivalent), photocatalyst
b
c
Zn6a (0.02 equivalent), in CH OH (5.0 mL). by LCMS, Yield
3
of the isolated product.
1
1
17
The photoreactions of naphthol (7a) were studied and its O
2
which could be assigned to TEMPO (TEMPꢀ O2 adduct).
65
generation efficiencies were compared among different
However, when 5,5ꢀdimethylꢀ1ꢀpyrroline Nꢀoxide (DMPO) was
used as the spin trapping agent for superoxide anion radicals and
hydroxyl radicals, no EPR signals were observed (even in the
presence of water, a condition favourable for the observation of
conjugates. Reactions were carried out in O atmosphere (1 atm),
2
2
5°C using 200 W mercury lamp and the reaction was monitored
the UVꢀVis changes. Naphthol 7a reacts with singlet oxygen to
generate the quinone 8a. Different zinc substituted
the DMPO–OH adduct signal). These results indicate that 3a
1
70 thiazolidinoneꢀporphyrin conjugates showed different singlet
oxygen generation efficiency and thus gave different yields of
quinone (Table 1).The reaction show excellent when Zn6a and
Zn3a used as the catalyst for the oxidative reaction (Table 1) and
the reaction was completed within one hour. Zn6a and Zn3a
showed O ꢀbased or Type II photodynamic activities.
2
Table
1 Photophysical characteristics of the porphyrinꢀ
b
thiazolidinone conjugates and % yields of the quinone 8a
7
5
gave 8a in 87% and 82% yield respectively. Furthermore, when
mono substituted and diꢀsubstituted conjugates used as
photocatalyst, slow conversion was observed and gave 8a in 60%
and 66% yield respectively. The scope and efficiency of Zn6a in
oxidative reaction was further explored by different naphthol
derivatives as well we also used less activated substrates such as
furan and the result are summarized in table 2.
80
Conclusion
In conclusion, we have synthesized and characterized a range
of newer meso and βꢀsubstituted thiazolidinone and porphyrin
conjugates. Their fluorescence and singlet oxygen quantum yields
were determined by various techniques. These porphyrin
conjugates showed red shift of their UVꢀVis spectra as compared
with simple TPP. The βꢀsubstituted zinc thiazolidinoneꢀporphyrin
85
Singlet oxygen efficiency of zinc thiazolidinoneꢀporphyrin
conjugates
was
qualitatively
evaluated
by
the
photodecomposition of 1,3ꢀdiphenylisobenzofuran (DPiBF) in the
4
5
presence of zinc thiazolidinoneꢀporphyrin conjugates (Table 1). 90 conjugate showed better singlet oxygen generation efficiency
Methanolic solution of zinc thiazolidinoneꢀporphyrin conjugates
than other thiazolidinoneꢀporphyrin conjugates.
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Experimental section
8H, mesoꢀArH), 5.78 (m, 4H, CH), 5.28 (m, 8H, CH
H, CH ), ꢀ2.821 (s, 2H, internal NH) ppm.
), 4.53 (s,
2
8
2
General
ꢀ
1
3
c: Dark brown; Yield: 36%; IR (KBr) v/cm : 3341, 3023,
All reactions were performed under a nitrogen atmosphere. 60 1765, 1545, 1435, 1321, 1005, 998, 861, 789; HRMS : m/z =
+
Pyrrole and aromatic aldehydes were purchased from Aldrich and
used without further purification. Solvents were purchased from
Merck and dried according to literature prior to use. Reactions
were monitored by thin layer chromatography (TLC) and
1242.1103 [M] (calculated 1242.1095); UVꢀVis (λnm; CHCl
3
1
5
0
5
0
5
0
5
0
5
0
5
solution): 421.3, 512.3, 551.7, 589.3, 651.9; H NMR (400 MHz,
CDCl ): δ =8.82 (s, 8H, β pyrrolic H), 8.39 (d, J = 8.4 Hz, 8H,
mesoꢀArH), 8.28 (d, J = 8.2 Hz, 8H, mesoꢀArH), 7.99 (s, 4H,
3
products were purified by column chromatography using 65 CH=C), 3.44 (s, 12H, CH ), ꢀ2.80 (s, 2H, internal NH) ppm.
3
1
ꢀ1
activated neutral aluminum oxide. H NMR spectra were
Zn3a: Red solid; Yield: 79%; IR (KBr) v/cm : 3031, 2924,
ꢀ
1
1
1
2
2
3
3
4
4
5
5
recorded in CDCl using a Jeol 400 MHz NMR spectrometer.
2874, 1698, 1483, 1471, 1382, 1251, 956, 810, 731 cm ; HRMS :
3
+
Chemical shifts are expressed in parts per million (ppm) relative
to tetramethylsilane (TMS, 0 ppm) as an internal standard.
m/z = 1608.1422 [M] (calculated 1608.1482); UVꢀVis (λnm;
1
CHCl3 solution): 430.9, 555.4, 595.9; H NMR (400 MHz,
1
3
Coupling constants (J) are reported in hertz (Hz). C NMR 70 CDCl ): δ = 8.70 (s, 8H, β pyrrolic H), 8.19 (d, J = 8.4 Hz, 8H,
3
spectra were recorded on Jeol 100 MHz NMR spectrophotometer.
Infrared spectra were recorded on a Perkin Elmer IR spectrometer
and absorption maxima are given in cm . A Perkin Elmer UV–
Vis spectrophotometer was used for UV measurements. The
mesoꢀArH), 7.98 (s, 4H, CH=C), 7.82ꢀ7.80 (d, J = 8.1 Hz, 8H,
mesoꢀArH), 7.46ꢀ7.44 (d, J = 7.8 Hz, 8H, benzylꢀArH), 7.31ꢀ7.24
ꢀ
1
(m, 12H, benzylꢀArH), 5.29 (s, 8H, CH ) ppm.
2
ꢀ
1
Zn3b: Dark brown; Yield: 39%; IR (KBr) v/cm : 2984, 3005,
fluorescence spectra were obtained by using a Shimadzu RFꢀ 75 1762, 1655, 1551, 1478, 1345, 981, 871, 750; HRMS : m/z =
+
5
301PC spectrofluorophotometer. The fluorescence quantum
yields of these compounds were determined by comparing to a
calibration standard of TPP in benzene solution with
1408.0841 [M] (calculated 1408.0856); UVꢀVis (λnm; CHCl
3
1
solution): 423.7, 549.8, 578; H NMR (400 MHz, CDCl ): δ =
3
a
8.58 (s, 8H, β pyrrolic H), 8.26 (d, J = 8.4 Hz, 8H, mesoꢀArH),
8.01 (s, 4H, CH=C), 7.61ꢀ7.59 (d, J = 8.1 Hz, 8H, mesoꢀArH),
80 5.75 (m, 4H, CH), 5.23 (m, 8H, CH ), 4.52 (s, 8H, CH ).
fluorescence quantum yield, of 0.11 (different refractive indices
of the solvents used in the standard and sample were corrected).
2
2
ꢀ
1
Zn3c: Dark red; Yield: 89%; IR (KBr) v/cm : 3031, 2854,
General procedure for the synthesis of porphyrinic
rhodanine derivative:
1759, 1541, 1455, 1312, 1010, 989, 863, 774, 510; HRMS : m/z =
+
1304.0223 [M] (calculated 1304.0230); UVꢀVis (λnm; CHCl
3
1
In a 25 mL round bottom flask, primary amine (5 mmol), CS2
solution): 420.87, 548.8, 576.1; H NMR (400 MHz, CDCl ): δ =
3
(8 mmol), ethyl chloroacetate (5 mmol), porphyrin aldehyde (1 85 8.79 (s, 8H, β pyrrolic H), 8.21 (d, J = 8.4 Hz, 8H, mesoꢀArH),
mmol) and catalytic amount of triethylamine (0.4 mmol) in THF
(5 mL) were mixed under nitrogen atmosphere and the reaction
was stirred at 80°C for the appropriate time. The reaction was
monitored by TLC. After completion of the reaction, the mixture
8.15 (d, J = 8.2 Hz, 8H, mesoꢀArH), 7.95 (s, 4H, CH=C), 3.41
(s, 12H, CH3).
Di-substituted
porphyrin-rhodanine(3-benzyl-2-thioxo-
thiazolidin-4-one) derivative (4a): Dark brown; Yield: 9%; IR
ꢀ
1
was poured into the water and the products were extracted with 90 (KBr) v/cm : 3211, 3011, 2891, 2691, 1699, 1534, 1441, 1345,
ꢀ
1
+
ethyl acetate. The organic layer was separated, washed with 2–3
times with water, dried over anhydrous sodium sulfate and
evaporated. The crude product was purified by column
chromatography on neutral alumina using 30% ethyl acetate
1002, 954, 812, 736 cm ; HRMS : m/z = 1108.2711 [M]
1
(calculated 1108.2722); H NMR (400 MHz, CDCl ): δ = 8.86ꢀ
3
8.78 (dd, 8H, βꢀpyrrolic H), 8.29ꢀ8.26 (d, 4H, mesoꢀArH), 8.04 (
s, 2H, CH), 7.87ꢀ7.85 (d, 4H, mesoꢀArH), 7.67 (d, 4H, mesoꢀ
(EtOAc) in hexane as an eluent to give rhodanine conjugated 95 ArH), 7.56 (d, 4H, mesoꢀArH), 7.31 (m, 4H, ArH benzyl), 7.15
porphyrins in 15ꢀ18%.
(m, 6H, ArH benzyl), 5.39 (s, 4H, CH ) 2.59 (s, 6H, CH ), ꢀ2.92
2 3
(s, 2H, internal NH) ppm.
ꢀ
1
3a: Dark brown; Yield: 36%; IR (KBr) v/cm : 3369, 3018,
ꢀ
1
1
1
702, 1525, 1473, 1348, 966, 802, 734 cm ; HRMS : m/z =
546.2341 [M] (calculated 1546.2347); UVꢀVis (λnm; CHCl3
5-(3-benzyl-5-benzylidene-2-thioxo-thiazolidin-4-one)-
+
10,15,20-tri(4-methylphenyl)porphyrin (5a): Dark brown;
1
ꢀ1
solution): 431.1, 521.6, 559.9, 597.3, 650.9; H NMR (400 100 Yield: 18%; IR (KBr) v/cm : 3341, 3301, 2845, 2798,1731,
+
MHz, CDCl ): δ = 8.78 (s, 8H, β pyrrolic H), 8.28ꢀ8.26 (d, J =
8.4 Hz, 8H, mesoꢀArH), 8.01 (s, 4H, CH=C), 7.84ꢀ7.82 (d, J =
1574, 1451, 1361, 1006, 841; HRMS : m/z = 890.2522 [M+H]
3
1
(calculated 889.2909); H NMR (400 MHz, CDCl ): δ = 8.85 (d,
3
8
.1 Hz, 8H, mesoꢀArH), 7.48ꢀ7.47 (d, J = 7.8 Hz, 8H, benzylꢀ
2H, β pyrrolic H), 8.81 (s, 6H, β pyrrolic H), 8.39ꢀ8.37 (d, J = 8.4
Hz, 6H, mesoꢀArH), 8.33ꢀ8.31 (d, J = 8.0 Hz, 2H, mesoꢀArH),
ArH), 7.33ꢀ7.27 (m, 12H, benzylꢀArH), 5.34 (s, 8H, CH ), ꢀ2.84
2
1
3
(s, 2H, internal NH) ppm; C NMR (100 MHz, CDCl ): δ = 105 8.29ꢀ8.27 (d, J = 8.1 Hz, 6H, mesoꢀArH), 8.05 (s, 1H, CH=C),
3
4
3.51, 115.24, 118.16, 120.38, 124.53, 125.84, 126.48, 140.08,
142.90, 145.92, 170.29, 196.42 ppm.
b: Dark brown; Yield: 28 %; IR (KBr) v/cm : 3356, 2984,
085, 3020, 1742, 1598, 1488, 1354, 988, 874, 754; HRMS : m/z
7.80ꢀ7.87 (d, J = 8.4 Hz, 2H, mesoꢀArH), 7.89 (m, 2H, ArH),
7.87 (m, 3H, ArH), 5.38 (s, 2H, CH ), 2.50 (d, 9H, CH ), ꢀ2.83 (s,
2
3
ꢀ
1
3
2H, internal NH) ppm; CHN: Obtained C, 78.16; H, 4.50; N,
6.98; S, 7.51 (calculated C, 78.26; H, 4.87; N, 7.87; S, 7.20).
3
=
+
1347.1722 [M+H] (calculated 1346.1721); UVꢀVis (λnm; 110
β-Substituted
porphyrin-rhodanine(3-benzyl-2-thioxo-
1
CHCl solution): 424.5, 518.5, 560.2, 591.2, 654.3; H NMR (400
MHz, CDCl ): δ = 8.64 (s, 8H, β pyrrolic H), 8.31 (d, J = 8.4 Hz,
8
thiazolidin-4-one) zinc complex (Zn6a): Green; Yield: 81%; IR
3
ꢀ
1
3
(KBr) v/cm : 3011, 2891, 2816, 2785, 1751, 1564, 1436, 1391,
+
H, mesoꢀArH), 8.01 (s, 4H, CH=C), 7.64ꢀ7.62 (d, J = 8.1 Hz,
1102, 830; HRMS : m/z = 965.2245 [M] (calculated 965.2200);
1
H NMR (400 MHz, CDCl ): δ = 8.91 (s, 1H, pyrrolic H), 8.89ꢀ
3
4
| Journal Name, [year], [vol], 00–00
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DOI: 10.1039/C6RA03489F
8
.83 (m, 6H, pyrrolic H), 817ꢀ8.15 (m, 8H, PhH),7.97 (d, 2H,
PhH), 7.76ꢀ7.72 (m, 12H, PhH), 7.56ꢀ7.51 (m, 5H, PhH), 7.28 (s,
H CH), 5.27 (s, 2H, CH2).
β-Substituted porphyrin-rhodanine(3-methyl-2-thioxo-
thiazolidin-4-one) (6c): Dark brown; Yield: 10%; IR (KBr)
Crossley, T. W. Schmidt, J. Phys. Chem. Lett., 2011, 2, 966ꢀ
9
71.
5
6
.
.
H. Abramczyk, B. BrozekꢀPluska, M. Tondusson, E. Freysz, J.
Phys. Chem. C, 2013, 117, 4999ꢀ5013.
A. O. Ribeiro, J. P. C. Tome, M. G. P. M. S. Neves, A. C.
Tome, J. A. S. Cavaleiro, Y. Iamamoto, T. Torres,
Tetrahedron Lett., 2006, 47, 9177ꢀ9180.
1
6
6
7
7
0
5
0
5
5
ꢀ
1
v/cm : 3361, 3014, 2986, 2851, 2841, 1658, 1577, 1441, 1341,
+
7. R. Bonnett, B. D. Djelal, A. Nguyen, J. Porphyrins
Phthalocyanines, 2001, 5, 652−661.
1
041, 935; HRMS : m/z = 827.2821 [M] (calculated 827.2753);
1
H NMR (400 MHz, CDCl ): δ = 8.90 (d, 1H, pyrrolic H), 8.86
3
8
.
S. Silva, P.M. R. Pereira, P. Silva, F. A. A. Paz, M. A. F.
Faustino, J. A. S. Cavaleiroa and J. P. C. Tome, Chem.
Commun., 2012, 48, 3608ꢀ3610.
Z. Valicseka, O. Horvátha, K. Patonay, J. Photochem.
Photobiol. A: Chem. 2011, 226, 23ꢀ35.
(m, 5H, pyrrolic H), 8.77 (d, 2H, βꢀ pyrrolic H), 8.21ꢀ8.09 (m,
1
1
2
2
3
3
0
5
0
5
0
5
8H, PhH),7.47 (s, 1H, CH), 7.791ꢀ7.73 (m, 12H, PhH), 3.37 (s,
3
9
1
.
H ꢀ2.59 (s, 2H, inner NH).
Photooxidation of Naphthols to Naphthoquinone:
Photocatalyst (0.02 equivalent) was added to a stirred solution
0. J. F. Lovell, T. W. B. Liu, J. Chen and G. Zheng, Chem. Rev.,
010, 110, 2839ꢀ2857.
2
of naphthol (0.5 mmol) in methanol (5 mL). The reaction mixture
was stirred at 25 °C under air atmosphere. The solution was then
irradiated using a 200 W mercury lamp. LCMS and TLC were
used to monitor the progress of the reaction. After the reaction is
completed, the solvent was evaporated under reduced pressure.
The mixture was purified by column chromatography.
11. H. M. Wang, J. Q. Jiang, J. H. Xiao, R. L. Gao, F. Y. Lin and
X. Y. Liu, ChemicoꢀBiological Interactions, 2008, 172, 154ꢀ
158.
1
2. B. Marydasan, A. K. Nair and D. Ramaiah, J. Phys. Chem. B,
013, 117, 13515ꢀ13522.
2
1
3. A. Lembo, P. Tagliatesta and D. M. Guldi, J. Phys. Chem. A,
2006, 110, 11424ꢀ11434.
14. W.ꢀZ. Ke, L. Wang, B. Song, J.ꢀX. Yang, Y.ꢀP. Tian, Y.ꢀH.
Kan, X.ꢀT. Tao and M.ꢀH. Jiang, Inorg. Chem. Commun.,
2011, 14, 1311ꢀ1313.
5. E. Annoni, M. Pizzotti, R. Ugo, S. Quici, T. Morotti, M.
Bruschi and P. Mussini, Eur. J. Inorg. Chem., 2005, 3857ꢀ
3874.
ꢀ
1
8a. Light yellow; Yield: 87%; IR (KBr) v/cm : 3103, 3044,
80
85
90
2
1
654, 1655, 1636, 1455, 1410, 1284, 1245, 901, 654. LCMS m/z:
+
1
58.0311 [M+H] (calculated 158.0368). H NMR (400 MHz,
1
CDCl /CD OD): δ = 8.10ꢀ8.09 (m, 2 H), 7.80ꢀ7.78 (m, 2H), 7.04
3
3
(s, 2H).
ꢀ
1
1
1
6. J. A. Shelnutt and V. Ortiz, J. Phys. Chem., 1985, 89, 4733ꢀ
8b. Yellow; Yield: 82%; IR (KBr) v/cm : 3771, 3087, 3066,
4
739.
7. N. C. Maiti and Ravikanth, J. Chem. Soc., Faraday Trans.,
996, 92, 1095ꢀ1100.
18. I. Gupta and M.
360, 1731‐1742.
9. I. Gupta and M. Ravikanth, J. Chem. Sci., 2005, 117, 161ꢀ166.
20. Y. Lion, M. Delmelle and A. V. D. Vorst, Nature, 1976, 263,
42ꢀ443.
2
673, 1667, 1601, 1466, 1449, 1397, 1262, 1205, 1101, 945, 860.
+
1
LCMS m/z: 175.0313 [M+H] (calculated 174.0317). H NMR
1
6
(400 MHz, CDCl /DMSOꢀd ): δ = 11.79 (s, 1H); 7.73 (t, J = 7.8
3
Ravikanth, Inorg. Chim. Acta, 2007,
Hz, 1H); 7.65 (d, J = 8.1 Hz, 1H); 7.50 (d, J = 7.3 Hz, 1H); 7.38
(d, J = 8.4 Hz, 1H); 7.15 (t, J = 8.5 Hz, 1H).
1
ꢀ
1
8
c. Dark yellow; Yield: 92%; IR (KBr) v/cm : 3694, 3047,
4
3
004, 2641, 1641, 1481, 1354, 1284, 1105, 910, 833, 614. LCMS
9
5
21. Z. Zeng, J. Zhou, Y. Zhang, R. Qiao, S. Xia, J. Chen, X. Wang
+
1
m/z: 175.0329 [M+H] (calculated 174.0317). H NMR (400
and B. Zhang, J. Phys. Chem. B, 2007, 111, 2688ꢀ2696.
MHz, CDCl /CD OD): δ = 7.99 (d, J = 8.3 Hz, 1H), 7.43 (s, 1H),
7.11 (d, J = 7.9 Hz, 2 H), 6.90 (s, 2H).
3
3
100
Acknowledgment
This research work was financially supported by Department
of Science and Technology (DST) New Delhi, DUꢀDST Purse
grant and University of Delhi. K. K. Yadav and S. Bhattacharya 105
are thankful to UGC New Delhi and U. Narang is thankful to
CSIR New Delhi for their senior research fellowships.
4
0
Supplementary Material
110
Supplementary data related to this article can be found at
http://dx.doi.org/
4
5
Notes and references
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This journal is © The Royal Society of Chemistry [year]
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DOI: 10.1039/C6RA03489F
Synthesis, properties and singlet oxygen generation of thiazolidinone double bond linked
porphyrin at meso and β-position
Sohail Ahmad, Kumar KaritkeyYadav, Uma Narang, Soumee Bhattacharya, Sarangthem Joychandra
Singh and S. M. S. Chauhan∗
Bio-organic laboratory, Department of Chemistry, University of Delhi, Delhi-110007, India