Synthesis, Spectroscopic Characterization and Polymerization Abilities of Blue and Green Light Emitting Oxazol-5-one Fluorophores

Article abstract of DOI:10.1007/s10895-018-2234-3

New fluorescent thiophenyl group containing oxazol-5-one fluorophores of 3a (4-(3-thiophenylmethylene)-2-phenyloxazol-5-one), 3b (4-(3-thiophenylmethylene)-2-(4-tolyl)oxazol-5-one) and 3c (4-(3-thiophenylmethylene)-2-(4-nitrophenyl)oxazol-5-one) were synthesized and characterized. The newly synthesized oxazol-5-ones absorption and fluorescence characteristics were studied in some solvents of varying polarities. The heterocyclic chromophores were fluorescent, with two of them, 3a and 3b, emitting blue light, whilst the other one, 3c, emitting green light. The emission maxima of the derivatives varied between 415 and 572?nm according as the extent of conjugation and solvent polarity. As solvent polarity increased, 3c derivatives emission spectra displayed a large bathochromic shift, which revealed the considerable change of the dipole moment of the fluorescent structure because of an intramolecular charge transfer interaction. Furthermore, oxazolones polymerization ability via the thiophenyl group linked to the oxazol-5-one heterocycle showed that copolymerization of 3a was achieved, but homopolymerization was not observed.

Full text of DOI:10.1007/s10895-018-2234-3

Journal of Fluorescence
https://doi.org/10.1007/s10895-018-2234-3
ORIGINAL ARTICLE
Synthesis, Spectroscopic Characterization and Polymerization Abilities
of Blue and Green Light Emitting Oxazol-5-one Fluorophores
Gulsiye Ozturk Urut1 & Seher Aydin1 & Derya Topkaya1 & Elif Sahin1 & Serap Alp1
Received: 26 February 2018 /Accepted: 23 April 2018
#
Springer Science+Business Media, LLC, part of Springer Nature 2018
Abstract
New fluorescent thiophenyl group containing oxazol-5-one fluorophores of 3a (4-(3-thiophenylmethylene)-2-phenyloxazol-5-
one), 3b (4-(3-thiophenylmethylene)-2-(4-tolyl)oxazol-5-one) and 3c (4-(3-thiophenylmethylene)-2-(4-nitrophenyl)oxazol-5-
one) were synthesized and characterized. The newly synthesized oxazol-5-ones absorption and fluorescence characteristics were
studied in some solvents of varying polarities. The heterocyclic chromophores were fluorescent, with two of them, 3a and 3b,
emitting blue light, whilst the other one, 3c, emitting green light. The emission maxima of the derivatives varied between 415 and
572 nm according as the extent of conjugation and solvent polarity. As solvent polarity increased, 3c derivatives emission spectra
displayed a large bathochromic shift, which revealed the considerable change of the dipole moment of the fluorescent structure
because of an intramolecular charge transfer interaction. Furthermore, oxazolones polymerization ability via the thiophenyl
group linked to the oxazol-5-one heterocycle showed that copolymerization of 3a was achieved, but homopolymerization was
not observed.
.
.
.
.
Keywords Oxazol-5-one Thiophenes Copolymer Homopolymer Fluorescence
Introduction
surrounding medium is observed for the compounds having
electron donor-acceptor moieties [10]. Thus organic donor-
acceptor molecules were extensively utilized as fluorescent
probes in order to investigate their microenvironment
[11–16]. Long wavelength absorption and emission, high
molar absorptivity and large Stokes’ shift values are desired
features for the lasers and fluorescent molecules used in
biosensors; in this manner their determination is important.
Due to the exocyclic double bond at 4th position of het-
erocycle a highly conjugated π-system was formed and
promising photophysical properties were observed which
provided oxazol-5-ones to be applicable in electronics and
photonics [10, 17]. 4-benzylidene oxazol-5-ones gained
considerable potential for applications as molecular
switches due to the significant conformational alteration
related to E/Z geometrical isomerization [18, 19].
Benzylidene oxazol-5-ones have been reported as good
candidates for efficient photoswitches as they are easily
synthesized and feature good photoisomerization quantum
yields and are thermally stable [19]. Rodrigues and co-
workers have investigated two-photon absorption properties
of oxazol-5-one derivatives [10]. They have stated that the
oxazol-5-ones having upper two photon absorption cross
section have potential application like nonlinear optical
Because of having numerous reactive sites, oxazol-5-ones are
candidates for many applications and found many application
areas [1–22]. They took place in the preparation of many bio-
logically active molecules and were reported to be valuable
precursors for the preparation of non-natural amino acids, pep-
tides, and anticancer, antitumor compounds, heterocyclic com-
pounds used in biosensor applications, insecticides, tyrosinase
inhibitors and many other [1–5]. Moreover, oxazol-5-ones took
place in different organic synthesis like preparation of function-
alized oxazolinones, radical reaction, Pauson-Khand reaction,
cycloaddition reaction and many other reactions [2, 6–9].
The absorption and emission properties of the oxazol-5-
ones were investigated widely due to their promising fea-
tures [5, 8, 10–17, 19]. In the excited state an intramolec-
ular charge transfer due to a strong interaction with the
* Gulsiye Ozturk Urut
gulsiye.ozturk@deu.edu.tr; gulsiyeozturk@yahoo.com
1
Department of Chemistry, Faculty of Sciences, Dokuz Eylul
University, Tinaztepe Campus, 35160 Buca, Izmir, Turkey

J Fluoresc
sensors and also in bioimaging. For biological applications,
the nonlinear interaction with light is an advantage because
of decrease in photodamage and photobleaching, and
deeper penetration the red-shifted wavelength utilized in
multiphoton excitation [20]. The linear and non-linear
photophysical properties of unsaturated oxazol-5-ones
substituted with a dimethylamine group as electron donat-
ing and/or nitrile, nitro and benzimidazole moieties as ac-
ceptor in position 4 of phenyl moieties of some oxazolones
have been investigated [17].
Reactive polymers have gained increasing applications
in nonlinear optics, biomedical investigations such as gene
and drug delivery, biomolecule immobilization, biosensing,
immunodiagnostics, immune-isolation and guiding of the
functions of the cells [23–25]. The broad π-electron delo-
calization caused their large nonlinearity [23]. There is a
continuous attention toward nonlinear optical materials due
to their applicability in optical materials used for data
storage, communication, switching, computing, printers
and displays. Oxazol-5-ones have also been utilized as
monomers for polymer synthesis [24, 26–31] and their
functional polymers are interesting because of being very
reactive. Oxazol-5-ones gained attention due to their
photophysical features that offer their promising applica-
tions in photonics and electronics [23]. The functionalized
or dye-doped polymers are advantageous in nonlinear op-
tics, because of the photochemical features of the polymer
or the dye. These kinds of structures could be modified by
UV or visible radiation, that results in attracting physico-
chemical or physical alterations. Solvable azlactone bear-
ing copolymers and homopolymers were synthesized via
different polymerization methods [24, 25, 27, 29–31]. The
oxazol-5-one heterocycle reacts through ring-opening that
creates no byproducts [24–30].
In electronical and optical areas, the conducting poly-
mers could be used as low-cost and flexible materials
[32–38]. Among these polythiophenes have gained consid-
erable attention in both fields of academy and industry
and have been considered to be promising materials due
to having high conductivity, good chemical and thermal
stability, structural versatility and tunable electronic and
optical properties [32–37]. Polythiophene have applicabili-
ty in different areas like photovoltaic cells, light emitting
diodes, semiconductors and transistors [32–35, 37].
In this study it is aimed to combine the advantages of
oxazol-5-ones with thiophenes and reported on the synthe-
sis and spectroscopic characterization of fluorescent
thiophenyl containing oxazol-5-one fluorophores. The
thiophenyl group was attached to the oxazol-5-one core
via the vinyl bridge (Scheme 1). The absorption and emis-
sion properties of this set of oxazol-5-one derivatives was
investigated and discussed. Moreover, this oxazol-5-one
fluorophores polymerization ability was also investigated.
Experimental
Materials and Instrumentation
The reagents were obtained from Merck or Aldrich. Acetic
anhydride was distilled before use. The compounds were char-
acterized by infrared spectroscopy in a Thermo Scientific
1
model: Nicolet İS10 ATR-FTIR spectrometer and by H-
NMR in Bruker WH-400 NMR spectrometer (Coventry,
UK). The absorption measurements were studied on a
Schimadzu UV-1601 spectrophotometer (Tokyo, Japan). The
emission spectra were recorded on a Varian-Carry Eclipse
spectrofluorimeter (Mulgrave, Australia). The absorption
and emission features of the derivatives were studies in tetra-
hydrofuran (THF), dichloromethane ( DCM),
dimethyformamide (DMF) and acetonitrile (ACN) solvents
of spectroscopic grade. Electrochemical features of copoly-
mers were studied with an electrochemical analyzer (CH
Instruments 600; CH Instruments, Austin, TX), and a CV cell
containing a platinum wire working electrode, a Ag wire
pseudoreference electrode and a platinum wire counter elec-
trode system.
Synthesis
Synthesis of Aryl Chloride Intermediates (1)
The aryl chloride intermediates of 1 were prepared according
to the literature [39]. The obtained 1 intermediates: 1a: ben-
zoyl chloride, 1b: p-toluoyl chloride, 1c: p-nitrobenzoyl
chloride.
Synthesis of Aryl Glycine Intermediates (2)
The aryl glycine (hippuric acid) intermediates of 2 were pre-
pared according to the literature [17, 40]. The obtained
hippuric acid derivatives: 2a: benzoyl glycine (hippuric acid),
2b: p-toluoyl glycine, 2c: p-nitrobenzoyl glycine.
Synthesis of 3-Thiophenyl Moiety Bearing Oxazol-5-one
Fluorophores (3)
The common way for oxazol-5-ones synthesis can be
described as follows: 3-thiophenecarboxaldehyde, aryl
glycine (benzoyl glycine for 3a, p-toluoyl glycine for
3b and p-nitrobenzoyl glycine for 3c), sodium acetate
and acetic anhydride were stirred at a temperature of

J Fluoresc
O
O
O
O
HO
O
O
Cl
NH
O
N
H
S
S
SOCl2
NaOH
NH2CH2COOH
OH
+
R
R
R
R
1
2
3
Scheme 1 Synthetic route for 3 fluorophores (R; 3a: H; 3b: CH3; 3c: NO2)
100–120 °C for two hours in a flask. After the accom-
plishment of the reaction, the blend was let to cool down
until it reached the room temperature. Then addition of
ethanol precipitated the product and the precipitate ob-
tained was separated and washed several times with eth-
anol. When further purification was necessary, recrystal-
lization was applied for some of the derivatives in a
suitable solvent or they were purified via column
chromatography.
8.40–8.37 (2H, m, CHar); 8.35–8.31 (2H, m, CHar); 8.23–8.22
(1H, dd, J = 2.9 Hz, J = 1.1 Hz, CHthioph); 7.99–7.97 (1H, dd,
J = 4.9 Hz, J = 1.0 Hz, CHthioph); 7.46–7.44 (1H, dd, J =
5.1 Hz, J = 2.9 Hz, CHthioph); 7.42 (s, 1H, =CH-Cthioph).
Quantum Yield Values
A comparative procedure was utilized for quantum yield data
(ΦF) identification [41, 42]:
4-(3-Thiophenylmethylene)-2-Phenyloxazol-5-one, 3a
À
Á À
Á
2
ΦF ¼ Φstd x F Astdη2 = FstdA ηstd
ð1Þ
Yellow solid, yield 16%, mp 188 °C. ATR-FTIR (KBr, ῡmax
(cm−1)): 3093 (=C-H), 1785 (-O-C=O), 1646 (-C=N-), 1296
The fluorescence areas of the samples and the standard
are denoted as F and Fstd, respectively. The absorbance
values of the samples and standard are expressed as A and
Astd, respectively. η and ηstd refer to the refractive indexes of
solvents of the samples and standard, respectively. Quinine
sulphate (in 0.1 M H2SO4) (Φ = 0.54) [43, 44] was
employed as the standard.
1
(O-C=O), 1143 (O-C=N). H NMR (CDCl3, 400 MHz, δ
(ppm)): 8.19–8.18 (2H, d, J = 4 Hz, CHar); 8.15–8.17 (1H,
dd, J = 8.0 Hz, J = 1.2 Hz, CHthioph); 7.95–7.94 (1H, dd, J =
5.2 Hz, J = 0.8 Hz, CHthioph); 7.62–7.50 (m, 3H, CHar); 7.42–
7.40 (1H, dd, J = 5.2 Hz, J = 3.2 Hz, CHthioph); 7.29 (s, 1H,
=CH-Cthioph).
All the measurements were taken on the same slit width
and the emission spectra used to assess fluorescence quantum
yield were corrected for the spectral sensitivity of Varian-
Carry eclipse.
4-(3-Thiophenylmethylene)-2-(4-Tolyl)Oxazol-5-one, 3b
Yellow solid, yield 13%, mp 187 °C. ATR-FTIR (KBr, ῡmax
(cm−1)): 3093–3104 (=C-H), 1787 (-O-C=O), 1652 (-C=N-),
1149 (O-C=O). 1H NMR (CDCl3, 400 MHz, δ (ppm)): 8.17–
8.16 (1H, dd, J = 3.6 Hz, J = 1.2 Hz, CHthioph); 8.04–8.02 (2H,
d, J = 8.0 Hz, CHar); 7.93–7.91 (1H, dd, J = 5.2 Hz, J =
1.2 Hz, CHthioph); 7.40–7.38 (1H, dd, J = 4.8 Hz, J = 2.8 Hz,
CHthioph); 7.32–7.30 (2H, d, J = 8.0 Hz, CHar); 7.24 (s, 1H,
=CH-Cthioph); 2.44 (s, 3 H, -CH3).
Polymerization
Cyclic Voltammogram was carried out in 0.1 M
tetrabuthylammonium perchlorate (TBAP)/acetonitrile (AN)
/Boron trifluoride diethyl etherate (BFEE) (8:2, v/v) electro-
lyte–solvent combines with an array consisting of an electro-
chemical analyzer (CH Instruments 600; CH Instruments,
Austin, TX), and a CV cell including a platinum wire as the
working, a platinum wire as a counter electrode, and a Ag wire
pseudoreference electrode. Oxidative electropolymerization
of 3a, 3b and 3c were performed at room temperature by
potentiodynamic scanning at 100 mV/s. Electrochemical be-
havior of copolymers were investigated in same electrolyte–
4-(3-Thiophenylmethylene)-2-(4-Nitrophenyl)Oxazol-5-one,
3c
Orange solid, yield 10%, mp 225 °C. ATR-FTIR (KBr, ῡmax
(cm−1)): 3113 (=C-H), 1786 (-O-C=O), 1652 (-C=N-), 1518,
1333, 1315 (-O-N=O). 1H NMR (CDCl3, 400 MHz, δ (ppm)):

J Fluoresc
Fig. 1 Absorption spectra of 3 derivatives (3a: 5 × 10−6 M; 3b: 2 × 10−6 M; 3c: 1 × 10−5 M)
solvent system via adding 8.2 × 10−3 M thiophene (Th), be-
tween −1.6 Vand + 0.6 Vat 100 mV/s scan speed with cycling
voltammetry method [45, 46].
Results and Discussion
Absorption and Emission Features of 3 Derivatives
3 derivatives absorption and emission spectra in acetoni-
trile (ACN), dichloromethane (DCM), dimethylformamide
(DMF) and tetrahydrofuran (THF) are given in Figs. 1
and 2 and related results are presented in Table 1.
Oxazol-5-ones 3a and 3b have identical absorption spec-
tra, particularly in shape and one strong absorption max-
ima (Fig. 1). Moreover, the absorption and emission
wavelengths of 3a and 3b were monitored in the similar
range, i.e. for 3a absorption maxima between 355 and
360 nm, for 3b absorption maxima between 363 and
367 nm, and emission maxima for 3a and 3b between
415 and 423 nm indicating that methyl moiety in the aryl
abs
Table 1 UV-vis absorption maxima, λmax (nm), fluorescence
f
emission maxima, λmax (nm), Stokes’ shift, Δλ (nm), molar extinction
coefficient, ε (L ·mol−1 ·cm−1), and singlet energy, Es (kcal/mol) and
fluorescence quantum yield (Φ) of 3 derivatives in four different solvents
abs
f
Compound Solvent λmax
λmax Δλ
ε
Es
Φ
3a
3b
3c
THF
355
366
366
360
367
368
369
363
389
392
393
384
418
423
420
415
418
423
415
421
507
521
572
562
63 41,280 80.3 0.0008
57 78,160 77.9 0.0005
54 77,500 77.9 0.0007
55 51,500 79.2 0.0006
51 158,100 77.7 0.0010
55 115,450 77.5 0.0007
46 122,750 77.3 0.0008
58 123,950 78.5 0.0006
118 21,670 73.3 0.0066
129 19,930 72.5 0.0108
179 15,130 72.5 0.0218
178 20,250 74.2 0.0143
DCM
DMF
ACN
THF
DCM
DMF
ACN
THF
DCM
DMF
ACN
Fig. 2 Emission spectra of 3 derivatives obtained by excitation at 360 nm
for 3a, 368 nm for 3b and 392 nm for 3c

J Fluoresc
that the dipole moment of the molecule changed largely
by excitation because of an intramolecular charge transfer
interaction. This indicates π → π* transition which is
allowed strongly accompanied by charge transfer that is
from electron donating thiophenyl moiety to the electron
accepting nitro moiety. The enhanced solvent sensitivity
of emission maxima of 3c in comparison to its absorption
maxima could be explained by the increase of the mutual
effect among the solute and the solvent in the excited
state because of enhanced dipole moment when excited
[47]. When comparing solvent polarities with emission
maxima, deviation has been observed for ACN and
DMF. Although ACN relative polarity of 0.460 is higher
than that of DMF which is 0.368, the emission maxima is
shifted to shorter wavelength in ACN. This can be attrib-
uted to the structural difference of ACN and DMF.
Although ACN is more polar than DMF, in ACN there
is only cyano group to interact with the derivatives, while
in DMF in addition to nitrogen there is also carbonyl
group. As a result DMF interacts more with the deriva-
tives in their excited states even its polarity is lower than
ACN. While the Stokes’ Shift values of 3a and 3b were
observed in between 46 and 63 nm, the Stokes’ Shift
values of 3c increased dramatically in the range of 118–
179 nm. Similarly, to the absorption and emission prop-
erties also in the Stokes’ Shift values of 3a and 3b deriv-
atives negligible effect was observed by the change in
solvent polarity. However, for 3c as the polarity of the
solvent increased, the Stokes’ Shift value for 3c increased
from 118 nm in THF to 179 nm in DMF indicating stron-
ger stabilization in the excited state in higher polarity
solvents.
O
O
S
S
N
N
O
O
N
R
O
O
3a(R-H) and 3b (R-CH3)
Fig. 3 The conjugation pathways for 3 derivatives
3c
substituent has a negligible effect. Moreover, this similar-
ity ranges in absorption and emission maxima for 3a and
3b also reveals that these two derivatives have the same
conjugation pathway that is from the electron donating
thiophenyl moiety to electron withdrawing keto oxazol-
5-one fragment (Fig. 3). However, when introducing a
strong electron accepting -NO2 group on the 4- position
of the aryl moiety absorption maxima of 3c has shifted to
longer wavelength between 384 and 393 nm and also the
emission maxima has shifted to longer wavelength be-
tween 507 and 572 nm which can be explained in terms
of enhanced conjugation pathway from electron donating
thiophenyl moiety to the electron withdrawing nitro
group. The change in solvent polarity has a remissible
influence over absorption maxima of 3 derivatives.
While 3a and 3b derivatives emission spectra were not
affected by the solvent polarity significantly, 3c derivative
exhibited a promising red shift from 507 nm in THF to
572 nm in DMF as solvent polarity increased which can
be attributed to strong electron acceptor nitro group. This
big bathochromic shift of emission maxima of 3c revealed
Molar extinction coefficients of 3b which ranging between
115,450–158,100 L.mol−1.cm−1 are higher than values for 3a
and 3c derivatives which are between 41,280–78,160 and
15,130–21,670 L.mol−1.cm−1, respectively.
Quantum yield values of the molecules were observed to be
low in the solvents used in this study (Table 1). 3c in dimethyl
formamide possessed the highest quantum yield value. The
Fig. 4 Cycling voltammograms
of 3a derivatives
homopolymerization
copolymerization

J Fluoresc
low quantum yields observed might be due to an effective
non-radiative deactivation pathway of the excess energy or a
quick intersystem crossing which presumably results in
quenching of singlet excited state of the structures.
nitrophenyl)oxazol-5-one) exhibited a strong bathochromic
shift in emission maxima indicating intensively photoinduced
intramolecular charge transfer in the singlet excited state.
Because of having long wavelength absorption and emission
maxima, elevated molar absorptivity and big Stokes’ shift
values, 3c derivative has the desired features for the fluores-
cent molecules. The electron acceptor and donor moieties
present in the π-electron delocalized 3 derivatives causes a
wide distribution of π-electron dispersion that induces an
asymmetric polarization. This property is assumed to encour-
age nonlinear interaction of the molecules with light.
The synthesized chromophore heterocycles could be prom-
ising candidates for optical materials utilized for areas like
biosensors, OLEDs or fluorescent probes.
Polymerization Ability
Our motivation for polymerization studies was the informa-
tion that sulphur containing five membered heterocyclic thio-
phene can be polymerized especially at 2 and 5 position and
that takes place in semi-conducting polymers.
The newly synthesized fluorophores polymerization abilities
were examined for copolymerization and homopolymerization.
The homopolymerization of 3a, 3b and 3c were investigated
with tetrabuthylamoniumperchlorate (TBAK) (0.1 M)
/acetonitrile (AN) cycling voltammetry method. The decreas-
ing cycles showed that homopolymerization was not obtained
(Fig. 4). In order to obtain the homopolymer electrochemically,
reduction oxidation peaks must increase reversibly. Reversible
rotational voltammograms were not obtained in this study.
Figure 4 shows the redox properties of monomer 3a and
copolymer via cyclic voltammetry (CV). An irreversible oxi-
dation peak was observed for homopolymerization of 3a at
Fig. 3 between −1.6 V and + 0.6 V at 100 mV/s scan speed
with cycling voltammetry method. With addition of thiophene
in the same solvent system, during successive cycling scans, a
new redox couple appeared at lower potentials (Ered. = −
0.30 V, −0,6 V and − 1,08 V; Eox. = −0.06 V and − 1,06 V),
which indicates the formation of a conducting copolymer of
3a fluorophore (P(3a-co-Th) between −1.6 V and + 0.0 V at
100 mV/s scan speed with cycling voltammetry method. The
peaks observed at −0.06 V and − 1.08 V for P(3a-co-Th)
showed decreasing attempt.
Also 3a copolymerization ability test obtained by ten cy-
cles gave a positive response, thus we aim to investigate its
polymerization characteristics and optical properties as well in
our further studies.
References
1. Zhang W, Barry JD, Cordova D, McCan SF, Benner EA, Hughes
KA (2014) Discovery, synthesis, and evaluation of N-substituted
amino-2(5H)-oxazolones as novel insecticides activating nicotinic
acetylcholine receptors. Bioorg Med Chem Lett 24:2188–2192
2. Cunha S, Filho RFD, Saravia KH, Azevedo-Santos AV, Menezes D
(2013) Synthesis of multi-functionalized 1-azabicycles through
MAOS acid catalyzed formal aza-[3+3] cycloaddition of heterocy-
clic enaminones with oxazolones. Tetrahedron Lett 54:3366–3370
3. Hamidian H, Tagizadeh R, Fozooni S, Abbasalipour V, Taheri A,
Namjou M (2013) Synthesis of novel azo compounds containing
5(4H)-oxazolone ring as potent tyrosinase inhibitors. Bioorg Med
Chem 21:2088–2092
4. Hamidian H, Azizi S (2015) Synthesis of novel compounds con-
taining morpholine and 5(4H)-oxazolone rings as potent tyrosinase
inhibitors. Bioorg Med Chem 23:7089–7094
In order to have conducting ability, there is need for suit-
able conjugation pathway which will provide the electrons
flow through the polymer chain. Our copolymer of 3a has a
potential for use as conducting polymers. In our next studies
we are planning to investigate its polymerization properties
and characteristics in more detail. The copolymers of 3b and
3c were not obtained.
5. Sun Y-F, Cui Y-P (2009) The synthesis, structure and spectroscopic
properties of novel oxazolone-, pyrazolone- and pyrazoline-
containing heterocycle chromophores. Dyes Pigments 81:27–34
6. Lu Z, Xu X, Yang Z, Kong L, Zhu G (2012) Approach to highly
functionalized oxazolones by a Pd-catalyzed cyclization of N-
alkynyl tert-butyloxycarbamates. Tetrahedron Lett 53:3433–3436
7. Zhou M-Q, Zuo J, Cui B-D, Zhao J-Q, You Y, Bai M, Chen Y-Z,
Zhang X-M, Yuan W-C (2014) Organocatalytic asymmetric double
Michael reaction of Nazarov reagents with alkylidene azlactones
for the construction of spiro-fused cyclohexanone/5-oxazolone sys-
tem. Tetrahedron 70:5787–5793
Conclusion
8. Micheau J-C, Coudret C, Kobeleva OI, Barachevsky VA,
Yarovenko VN, Ivanov SN, Litchitsky BV, Krayushkin MM
(2014) Quantitative study of photochromic transformations of
diarylethene derivatives with either perhydrocyclopentene or
oxazoloneor lactone units. Dyes Pigments 106:32–38
9. Liu H, Hua R (2016) Conversion of carbon dioxide into 2-
oxazolidinones and 2(3H)- oxazolones catalyzed by 2,20,200-
terpyridine. Tetrahedron 72:1200–1204
A set of thiophenyl group bearing oxazol-5-one derivatives
with electron donor and electron acceptor moieties have been
synthesized and characterized. The derivatives were synthe-
sized by substitution of the 4- position of the phenyl moiety of
the (4-(3-thiophenylmethylene)-2-phenyloxazol-5-one) with
–CH3 group (electron donor) and –NO2 (electron acceptor)
groups. Substitution of benzylidene with a nitro acceptor
leaded longer absorption and emission maxima. As the sol-
vent polarity increased (4-(3-thiophenylmethylene)-2-(4-
10. Rodrigues CAB, Mariz IFA, Maçoas EMS, Afonso CAM,
Martinho JMG (2012) Two-photon absorption properties of
pushepull oxazolones derivatives. Dyes Pigments 95:713–722

J Fluoresc
11. Singh AK, Darshi M, Kanvah S (2000) α,ω-Diphenylpolyenes
Cabable of exhibiting twisted intramolecular charge transfer fluo-
rescence: a fluorescence and fluorescence probe study of nitro- and
Nitrocyano-substituted 1,4-Diphenylbutadienes. J Phys Chem A
104:464–471
12. Szdlowska I, Kyrychenko A, Nowacki J (2003) Photoinduced in-
tramolecular electron transfer in 4-dimethylaminopyridines. J. Phys
Chem Chem Phys 5:1032–1038
29. Speetjens FW, Carter MCD, Kim M, Gopalan P, Mahanthappa MK,
Lynn DM (2014) Post-fabrication placement of arbitrary chemical
functionality on microphase-separated thin films of amine-reactive
block copolymers. Macro Lett 3:1178–1182
30. Guyomard A, Fournier D, Pascual S, Fontaine L, Bardeau J-F
(2004) Preparation and characterization of azlactone functionalized
polymer supports and their application as scavengers. Eur Polym J
40:2343–2348
13. Davis R, Das S, George M, Druzhinin ZD, Zackariasse KA (2001)
Intramolecular charge transfer and photochemical isomerization in
donor/acceptor-substituted Butadienes. J Phys Chem A 105:4790–4798
14. Hermant RM, Bakker NAC, Scherer T, Kriijnen B, Verhoeven JW
(1990) Systematic study of a series of highly fluorescent rod-shaped
donor-acceptor systems. J Am Chem Soc 112:1214–1221
15. Doroshenko AO, Pivovarenko VG (2003) Fluorescence quenching
of the ketocyanine dyes in polar solvents: anti-TICT behavior. J
Photochem Photobiol A Chem 156:55–64
16. Rurak K, Bricks JL, Reck G, Radieglia R, Reach-Genger U (2000)
Chalcone-analogue dyes emitting in the near-infrared (NIR): influ-
ence of donor−acceptor substitution and cation complexation on
their spectroscopic properties and X-ray structure. J Phys Chem A
104:3087–3109
31. Pascual S, Blin T, Saikia PJ, Thomas M, Gosselin P, Fontaine L
(2010) Block copolymers based on 2-Vinyl-4,4-dimethyl-5-
oxazolone by RAFT polymerization: experimental and computa-
tional studies. J Polym Sci A Polym Chem 48:5053–5062
32. Zamora PP, Camarada MB, Jessop IA, Diaz FR, dell Valle MA,
Cattin L, Louarn BG (2012) Synthesis, characterization, morphol-
ogy and photovoltaic properties of aniline-Tiophene based poly-
mers. J C Int J Electrochem Sci 7:8276–8287
33. Cheylan S, Fraleoni-Morgera A, Puigdollers J, Voz C, Setti L,
Alcubilla R, Badenes G, Costa-Bizzarri P, Lanzi M (2006) Study
of a thiophene-based polymer for optoelectronic applications. Thin
Solid Films 497:16–19
34. Bünnagel TW (2008) Thiophene-based polymers and oligomers for
organic semiconductor applications. Shaker Verlag GmbH, Aachen
35. Sonar P, Benmansour H, Geiger T, Schlüter AD (2007) Thiophene-
based dendronized macromonomers and polymers. Polymer 48:
4996–5004
17. Rodrigues CAB, Mariz IFA, Maçoas EMS, Afonso CAM,
Martinho JMG (2013) Unsaturated oxazolones as nonlinear
fluorophores. Dyes Pigments 99:642–652
18. Blanco-Lomas M, Samanta S, Campos PJ, Woolley GA, Sampedro
D (2012) Reversible photocontrol of peptide conformation with a
rhodopsin-like photoswitch. J Am Chem Soc 134:6960–6963
19. Funes-Ardoiz I, Blanco-Lomas M, Campos PJ, Sampedro D (2013)
Benzylideneeoxazolones as photoswitches: photochemistry and
theoretical calculations. Tetrahedron 69:9766–9771
36. Seixas de Melo J, Burrows HD, Svensson M, Andersson MR,
Monkman AP (2003) Photophysics of thiophene based polymers
in solution: the role of nonradiative decay processes. J Chem Phys
118:1550–1556
37. Smith ZC, Meyer DM, Simon MG, Staii C, Shukla D, Thomas SW
(2015) Thiophene-based conjugated polymers with Photolabile sol-
ubilizing side chains. Macromolecules 48:959–966
38. Kumaresan P, Vegiraju S, Ezhumalai Y, Yau SL, Kim C, Lee W-H,
Chen M-C (2014) Fused-Thiophene based materials for organic pho-
tovoltaics and dye-sensitized solar cells. Polymers 6:2645–2669
39. Vogel A (1989) Practical organic chemistry, Fifth edn. Longman
Group, UK, p 792
40. Vogel A (1989) Practical organic chemistry, Fifth edn. Longman
Group, UK, p 585
41. Fery-Forgues S, Lavabre D (1999) Are fluorescence quantum
yields so tricky to measure? A demonstration using familiar statio-
nery products. J Chem Educ 76:1260
42. Maree D, Nyokong T, Suhling K, Phillips D (2001) Synthesis, spec-
troscopy and electrochemistry of octaphenoxyphthalocyaninato silicon
complexes. J Porphyrins Phthalocyanines 5:555–563
20. Köning K (2000) Multiphoton microscopy in life sciences. J
Microsc 200:83–104
21. Pattarawarapan M, Jaita S, Phakhodee W (2016) A convenient
synthesis of 4-arylidene-2-phenyl-5(4H)-oxazolones under
solvent-assisted grinding. Tetrahedron Lett 57:3171–3174
22. Dong H, Song S, Li J, Xu C, Zhang H, Ouyang L (2015) The
discovery of oxazolones-grafted spirooxindoles via three-
component diversity oriented synthesis and their preliminary bio-
logical evaluation. Bioorg Med Chem Lett 25:3585–3591
23. Smokal V, Czaplicki R, Derkowska B, Krupka O, Kolendo A,
Sahraoui B (2007) Synthesis and study of nonlinear optical prop-
erties of oxazolone containing polymers. Synth Met 157:708–712
24. Gardner CM, Brown CE, Stöver HDH (2012) Synthesis and prop-
erties of water-soluble Azlactone copolymers. J Polym Sci A Polym
Chem 50:4674–4685
43. Brouwer AM (2011) Standards for photoluminescence quantum
yield measurements in solution (IUPAC technical report). Pure
Appl Chem 83:2213–2228
44. Chandra S, Patra P, Pathan SH, Roy S, Mitra S, Layek A, Bhar R,
Pramanik P, Goswami A (2013) Luminescent S-doped carbon dots:
an emergent architecture for multimodal applications. J Mater
Chem B 1:2375–2382
45. Gunbas GE, Camurlu P, Akhmedov İM, Tanyeli C, Önal AM,
Toppare L (2008) A fast switching, low band gap, p- and n-dopable,
donor–acceptor type polymer. J Electroanal Chem 615:75–83
46. Sahin E, Camurlu P, Toppare L (2006) Both anodically and cathod-
ically coloring electrochromic polymer based on dithieno[3,4-b,3′,
4′-e]-[1,4]-dithiine. Synth Met 156:124–128
25. Laquievre A, Allaway NS, Lyskawa J, Woisel P, Lefebvre J-M,
Fournier D (2012) Highly efficient ring-opening reaction of
Azlactone-based copolymer platforms for the design of functional-
ized materials. Macromol Rapid Commun 33:848–855
26. Heilmann SM, Drtina GJ, Haddad LC, Rasmussen JK, Gaddam
BN, Liu JJ, Fitzsimons RT, Fansler DD, Vyvyan JR, Yang YN,
Beauchamp TJ (2004) Azlactone-reactive polymer supports for
immobilizing synthetically useful enzymes part I. Pig liver esterase
on dispersion polymer supports. J Mol Catal B Enzym 30:33–42
27. Ho HT, Levere ME, Pascual S, Moltembault V, Casse N, Caruso A,
Fontaine L (2013) Thermoresponsive block copolymers containing
reactive azlactone groups and their bioconjugation with lysozyme.
Polym Chem 4:675–685
28. Ho TH, Levere M, Soutif J-C, Montembault V, Pascual S, Fontaine
L (2011) Synthesis of thermoresponsive oxazolone end-functional
polymers for reactions with amines using thiol-Michael addition
Bclick^ chemistry. Polym Chem 2:1258–1260
47. Asiri AM, El-Daly SA, Khan SA (2012) Spectral characteristics of
4-(p-N,N-dimethyl-aminophenylmethylene)-2-phenyl-5-oxazolone
(DPO) in different media. Spectrochimica Acta A Mol Biomol
Spectrosc 95:679–684