Synthesis and photophysical properties of benzo[c]thiophene, p-phenylene-, triphenylamine-, and pyrene-based vinylenes

Article abstract of DOI:10.1080/00397911.2016.1228111

An efficient synthesis of benzo[c]thiophenyl/p-phenylenyl/pyrenyl phosphonate esters has been achieved using ZnBr₂-catalyzed Michaelis–Arbuzov reaction of corresponding benzyl alcohol/bromides at room temperature. Horner–Wadsworth–Emmons reacti

Full text of DOI:10.1080/00397911.2016.1228111

Synthetic Communications
An International Journal for Rapid Communication of Synthetic Organic
Chemistry
ISSN: 0039-7911 (Print) 1532-2432 (Online) Journal homepage: http://www.tandfonline.com/loi/lsyc20
Synthesis and Photophysical Properties of
Benzo[c]thiophene, p-Phenylene, Triphenylamine
and Pyrene Based Vinylenes
Meganathan Nandakumar, Elumalai Sankar & Arasambattu K.
Mohanakrishnan
To cite this article: Meganathan Nandakumar, Elumalai Sankar & Arasambattu K.
Mohanakrishnan (2016): Synthesis and Photophysical Properties of Benzo[c]thiophene, p-
Phenylene, Triphenylamine and Pyrene Based Vinylenes, Synthetic Communications, DOI:
10.1080/00397911.2016.1228111
To link to this article: http://dx.doi.org/10.1080/00397911.2016.1228111
View supplementary material
Accepted author version posted online: 03
Sep 2016.
Published online: 03 Sep 2016.
Submit your article to this journal
Article views: 7
View related articles
View Crossmark data
Full Terms & Conditions of access and use can be found at
http://www.tandfonline.com/action/journalInformation?journalCode=lsyc20
Download by: [Northern Illinois University]
Date: 09 September 2016, At: 14:44

Synthesis and Photophysical Properties of Benzo[c]thiophene, p-Phenylene,
Triphenylamine and Pyrene based Vinylenes
Meganathan Nandakumar1, Elumalai Sankar1, Arasambattu K. Mohanakrishnan1
1Department of Organic Chemistry, School of Chemistry, University of Madras, Chennai,
Tamil Nadu, India
Corresponding author Arasambattu K. Mohanakrishnan E-mail:
mohanakrishnan@unom.ac.in; mohan_67@hotmail.com
Abstract
An efficient synthesis of benzo[c]thiophenyl/p-phenylenyl/pyrenyl phosphonate esters
has been achieved using ZnBr2-catalyzed Michaelis-Arbuzov reaction of corresponding
benzyl alcohol/bromides at room temperature. Horner-Wadsworth-Emmons reaction of
the phosphonate esters with aryl/heteroaryl aldehydes in the presence of t-BuOK
furnished the vinylenes in good yields. The absorption and emission characteristics of the
synthesized vinylenes were also reported.
Graphical Abstract
KEYWORDS: Benzo[c]thiophene, Phosphonate ester, Michaelis-Arbuzov reaction,
Horner-Wadsworth-Emmons reaction, Vinylene, Pyrene, Triphenylamine
INTRODUCTION
1

The π-conjugated compounds containing vinyl unit have attracted prominent attention as
highly useful material for applications in organic light emitting diodes (OLEDs)[1],
photovoltaics (PV)[2], field-effect transistors (FET)[3] and organic solar cells (OSCs)[4].
Among them, thiophene-based π-conjugated vinylenes represent one of the most widely
investigated classes of functional π-conjugated vinylenes[5]. Since conjugated
benzo[c]thiophene derivatives are low band gap materials with interesting opto-electronic
properties[6], many research groups have undertaken a detailed study on
benzo[c]thiophenyl cyanovinylenes. Cava and co-workers[7] reported the synthesis and
photophysical properties of benzo[c]thiophene-based cyano-vinylenes. Recently,
p-phenylene incorporated benzo[c]thiophenyl cyano-vinylene has been synthesized and
investigated as an efficient donor for bulk heterojunction solar cells because of its low-
lying HOMO energy level[8]. However, the main disadvantage encountered in the
synthesis of benzo[c]thiophenyl vinylenes using Horner-Wadsworth-Emmons (HWE)
reaction of phosphonate ester with benzo[c]thiophene aldehyde 1 is it’s facile
decarbonylation into benzo[c]thiophene 5 (Scheme I)[7].
Organic materials derived from p-phenylene[9] and pyrenes[10] have gained prominent
attention due to their potential applications. Recently, Jayakannan and co-workers[11]
disclosed that oligophenylene vinylene substituted with aromatic cores displayed faster
excitation decay and excited state stability up to 10 ns. Jo and co-workers2a have reported
that the vinyl thiophene-linked with thiophenyl thieno[3,4-c]pyrrole-4,6-dione-based co-
polymer as a low band gap polymer with 7.16% power conversion efficiency (PCE) for
photovoltaic applications[4]. Black and co-workers1c have achieved the synthesis of bis-
2

(vinyl quinolinyl)benzene derivatives as thermally ss, low band gap and efficient
transporting material for organic light emitting diodes (OLEDs). The vinylenes derived
from dithienylbenzothiadiazole exhibited low band gap, broad as well as strong
absorption in the visible region and application in photovoltaic cells[12]. Lu and co-
workers have synthesized triphenylamine attached pyrenyl vinylenes and demonstrated
them as good emitter as well as excellent hole-transporting material[1a]
.
Recently, our research group has reported the synthesis and photophysical studies of
thienothiophene and dibenzoheterocycle tethered benzo[c]thiophenyl cyano-vinylenes[13]
Synthesis of phosphonate esters using ZnBr2-mediated Michaelis-Arbuzov reaction has
been established in our research group[14]. The present research work describes the
synthesis and characterization of benzo[c]thiophene, p-phenylene, triphenylamine and
pyrene based vinylenes from respective phosphonate esters and aldehydes.
.
RESULTS AND DISCUSSION
Keeping the decarbonylation of benzo[c]thiophene aldehyde 1 in mind, the preparation of
benzo[c]thiophenyl vinylene was planned using Horner-Wadsworth-Emmons (HWE)
reaction of benzo[c]thiophenyl phosphonate ester with heteroaryl aldehyde. Accordingly,
the reduction of benzo[c]thiophenyl aldehyde 1 using sodium borohydride in THF/EtOH
led to the isolation of benzo[c]thiophenyl methanol 6 in 79% yield. The benzyl alcohol 6
upon reaction with triethyl phosphite in the presence of 1 eq. of ZnBr2 at room
temperature for 8 h afforded phosphonate ester 7 as a thick red liquid in 86% yield
(Scheme II).
3

As expected, the HWE reaction of benzo[c]thiophenyl phosphonate ester 7 with
bithiophene aldehyde 8 using t-BuOK in dry THF at -15 oC for 1 h, followed by room
temperature stirring for 5 h furnished benzo[c]thiophenyl vinylene BT-BT as a dark red
solid in 59% yield (Scheme III). Next, 3,4-ethylenedioxythiophene (EDOT) tethered
benzo[c]thiophenyl vinylene BT-EDOT was also synthesized involving the HWE
reaction of phosphonate ester 7 with aldehyde 9. However, an attempt to synthesize
benzo[c]thiophene based vinylene 4 via condensation of the phosphonate ester 7 with
terephthaldehyde was found to unsuccessful, only the starting phosphonate ester 7 was
recovered unchanged.
The formation of benzo[c]thiophenyl vinylenes BT-BT and BT-EDOT confirmed
the synthetic utility of benzo[c]thiophenyl phosphonate ester 7 in HWE reaction. Hence,
the present approach provides an alternative route to the synthesis of benzo[c]thiophenyl
vinylenes by avoiding the decarbonylation problem associated with benzo[c]thiophene
aldehyde 1.[7]
We, next intended to synthesize phenylene and pyrene based vinylenes using the similar
protocol. The known dibromo compound 10 upon Michaelis-Arbuzov reaction with
triethyl phosphite in the presence of 1 eq. of ZnBr2 at rt for 10 h led to the isolation of
diphosphonate ester 11 in 83% yield (Scheme IV).
4

As a representative case, the reaction of diphosphonate ester 11 with terthiophenyl
aldehyde 12 in the presence of t-BuOK furnished vinylene PP-TT as a red solid in 79%
yield. Under identical conditions, the pyrene and triphenylamine based vinylenes PP-PY
and PP-TPA were also obtained in good yields (Scheme IV).
Finally, the pyrenyl phosphonate ester 16 was prepared from pyrene-1-
carboxaldehyde 13. The pyrenyl aldehyde 13 upon reduction with NaBH4 in THF/EtOH
at rt for 5 h gave pyrene-1-methanol 15 as a pale yellow solid in 75% yield.[14] The Lewis
acid-mediated Michaelis-Arbuzov reaction of pyrenyl methanol 15 with triethyl
phosphite in the presence of ZnBr2 at rt for 8 h led to the isolation of phosphonate ester
16 as a colorless solid in 81% yield (Scheme V).
As expected, the pyrenyl phosphonate ester 16 upon condensation with triphenylamine
aldehyde 14 in the presence of t-BuOK furnished vinylene PY-TPA as a yellow solid in
72% yield. The EDOT aldehyde 9 also underwent smooth condensation with
phosphonate ester 16 to furnish the respective vinylene PY-EDOT as a yellow solid in
69% yield (Scheme VI).
Under identical conditions, the symmetrical pyrenyl and bis-pyrenyl vinylenes
PY-PY/PY-PVPY were also synthesized (Scheme VII).
The optical properties of the synthesized vinylenes were investigated by
UV-vis and fluorescence spectroscopy.
5

The electronic absorption and photoluminescence (PL) spectra of vinylenes (10-5 M) were
measured in dichloromethane (DCM) solution. The luminescence spectra were recorded
by exciting at the longest wavelength of the absorption maxima. The UV-vis and
fluorescence spectral data of benzo[c]thiophenyl vinylenes (BT-BT, BT-EDOT), 1,4-
dihexyloxybenzene conjugated vinylenes (PP-TT, PP-PY and PP-TPA) and pyrene
based vinylenes (PY-TPA, PY-EDOT, PY-PY and PY-PVPY) are presented in Scheme
VIII.
The UV-vis spectra of benzo[c]thiophenyl vinylenes BT-BT and BT-EDOT exhibited
strong absorption in the region of 350-600 nm attributed to the π-π* electronic transition
of the π-conjugated backbone. Both bithiophene and EDOT-linked benzo[c]thiophenyl
vinylenes (BT-BT and BT-EDOT) showed redshifted λmax compared to the parent 1,3-
dithienyl benzo[c]thiophene 5. Among these two vinylenes, the bithiophenyl vinylene
BT-BT displayed redshifted absorption as well as emission compared to the EDOT-based
vinylene BT-EDOT (Figure I).
Stokes shift values of vinylenes have been mentioned in the Scheme VIII.
Benzo[c]thiophene based vinylenes BT-BT and BT-EDOT exhibited larger Stokes
shift values (4643 and 4452 cm-1) compared to 1,4-dihexyloxybenzene as well as pyrene-
based vinylenes.
6

Similarly, the phenylene vinylenes PP-TT, PP-PY and PP-TPA displayed broad
absorption peak in the region of 300-550 nm due to the π-π* electronic transition of the
conjugated system. Among these vinylenes, the terthiophenyl vinylene PP-TT exhibited
redshifted absorption as well as emission spectra (Figure II).
Both the pyrenyl and triphenylamino vinylenes PP-PY and PP-TPA showed comparable
UV-vis absorption spectra. However, the pyrenyl vinylene PP-PY displayed higher
emission wavelength than the triphenylamino vinylenes PP-TPA. The pyrene tethered
vinylenes PY-TPA, PY-EDOT, PY-PY & PY-PVPY showed broad absorption in the
region of 350-475 nm and emission in the region of 400-575 nm (Figure III). Interactions
between conjugated pyrene units and intramolecular charge transfer (ICT) in PY-TPA
and PY-EDOT led to the disappearance of the featured vibronic pattern of pyrene and
broadening of UV-vis absorption and fluorescence spectra.[17] Among the pyrenyl
vinylenes, the highly conjugated di-vinylene PY-PVPY displayed redshifted absorption.
The absorption and emission spectral data of triphenylamine and pyrene based
conjugated vinylenes PY-TPA/PY-PY were found to be comparable. The EDOT based
vinylene PY-EDOT showed blue shifted absorption and emission characteristics
compared to other pyrenyl vinylenes.
CONCLUSION
In conclusion, the 1,3-dithienylbenzo[c]thiophenyl/1,4-dihexyloxybenzene/ pyrenyl
phosphonates esters were prepared using ZnBr2-mediated Michaelis-Arbuzov reaction of
respective benzylic methanol/bromide. The synthesis of benzo[c]thiophene/p-
7

phenylene/pyrene based vinylene derivatives were achieved in good yields involving
HWE reaction of corresponding phosphonate esters with aryl/heteroaryl aldehydes. The
photophysical properties of the synthesized vinylenes were also presented.
EXPERIMENTAL
All melting points were uncorrected. Reagents were purchased from commercial sources
and used as received without purification. Solvents were dried by standard procedures.
Column chromatography was carried on silica gel (grade 60, mesh size 230-400, Merck).
1H and 13C NMR spectra were recorded in CDCl3 using TMS as an internal standard on a
Bruker-300 spectrometer. Chemical shift values were quoted in ppm and coupling
constants were quoted in Hz. Chemical shift multiplicities were reported as s = singlet, d
= doublet, t = triplet, q = quartet, m = multiplet. The aldehydes 8, 9, 12, 13, 14 and 17
were commercially available. The phosphonate esters 7, 11 and 16 were prepared (see SI
for details) adopting published procedure.[14a]
Preparation Of Vinylene BT-BT
To a solution of phosphonate ester 7 (0.10 g, 0.223 mmol) in dry THF, t-BuOK (0.05 g,
0.446 mmol) in dry THF was added slowly at -15 oC and stirred at same temperature for
30 min to ensure the completion of phosphonate ester anion generation. To this,
bithiophene aldehyde 8 (0.06 g, 0.219 mmol) in dry THF was slowly added and stirred at
-15 oC for 1 h. Then, the reaction mixture was slowly raised to rt and stirred for 5 h. After
the disappearance of the starting materials, the reaction mixture was poured over crushed
ice. The red solid obtained was filtered and crystallized from methanol to give vinylene
8

BT-BT as a dark red solid. 0.08 g (59%). mp > 350 oC. 1H-NMR (300 MHz, CDCl3): δ
8.00-7.93 (m, 2 H, ArH), 7.38-7.34 (m, 2 H, ArH), 7.25-7.21 (m, 2 H, ArH), 7.17-7.14
(m, 4 H, ArH), 7.07-7.00 (m, 5 H, ArH), 6.94-6.93 (m, 1 H, ArH) ppm. 13C-NMR (75
MHz, CDCl3): δ 142.1 (C), 141.5 (C), 137.1 (C), 136.4 (C), 136.2 (C), 136.0 (C), 135.6
(C), 135.5 (C), 135.2 (C), 134.8 (C), 127.9 (2 C-H), 127.4 (C-H), 126.8 (C-H), 125.8 (C-
H), 125.7 (C-H), 125.7 (C-H), 125.0 (C-H), 124.9 (C-H), 124.6 (C-H), 124.5 (C-H),
124.4 (C-H), 124.2 (C-H), 123.8 (C-H), 121.7 (C-H), 121.2 (C-H) ppm. HRMS (EI): m/z
cacld for C26H16S5 [M+]: 487.9856, found: 487.9853.
Preparation Of Vinylene PP-TPA
Reaction of diphosphonate ester 11 (0.20 g, 0.35 mmol) with triphenylamine aldehyde 14
(0.21 g, 0.761 mmol) using t-BuOK (0.194 g, 1.73 mmol) the procedure similar to that of
BT-BT furnished vinylene PP-TPA (0.21 g, 75%) as a yellow solid. mp 160-162 oC; 1H-
NMR (300 MHz, CDCl3): δ 7.50-7.39 (m, 8 H, ArH), 7.37-7.16 (m, 8 H, ArH), 7.15-7.01
(m, 18 H, ArH), 4.05-4.03 (m, 4 H, Ar-CH2), 1.90-1.85 (m, 4 H, CH2), 1.58-1.37 (m, 12
H, CH2), 0.99-0.91 (m, 6 H, CH3) ppm. 13C-NMR (75 MHz, CDCl3): δ 151.1 (C), 147.7
(C), 147.2 (C), 132.4 (C), 129.3 (C-H), 128.1 (C-H), 127.4 (C-H), 127.0 (C), 124.5 (C-
H), 123.7 (C-H), 123.0 (C-H), 122.0 (C-H), 110.6 (C-H), 69.7 (OCH2), 31.7 (CH2), 29.5
(CH2), 26.0 (CH2), 22.7 (CH2), 14.1 (CH3) ppm. HRMS (EI): m/z cacld for C58H60N2O2
[M+]: 816.4655, found: 816.4652.
Preparation Of Vinylene PY-PY
9

Reaction of phosphonate ester 16 (0.20 g, 0.67 mmol) with pyrenyl aldehyde 13 (0.14 g,
0.62 mmol) using t-BuOK (0.16 g, 1.42 mmol) the procedure similar to that of BT-BT
furnished vinylene PY-PY (0.18 g, 75%) as a yellow solid. mp > 300 oC; 1H-NMR (300
MHz, CDCl3): δ 8.62 (d, J = 9.6 Hz, 2 H, ArH), 8.56 (d, J = 8.1 Hz, 2 H, ArH), 8.46 (s, 2
H, Vinyl-CH), 8.28 (d, J = 8.1 Hz, 2 H, ArH), 8.23-8.17 (m, 6 H, ArH), 8.14-8.01 (m, 6
H, ArH) ppm. HRMS (EI): m/z cacld for C34H20 [M+]: 428.1565, found: 428.1563.
SUPPORTING INFORMATION
Experimental procedures for starting materials as well as vinylenes, copies of 1H and 13C
NMR spectra of vinylenes. This material can be found via the “Supplementary Content”
section of this article’s webpage.
REFERENCES
1
(a) Zhan, Y.; Peng, J.; Ye, K.; Xue, P.; Lu, R. Org. Biomol. Chem., 2013, 11,
6814. (b) Jana, D.; Boxi, S.; Parui, P. P.; Ghorai, B. K. Org. Biomol. Chem., 2015, 13,
10663. (c) Kathirgamanathan, P.; Surendrakumar, S.; Ravichandran, S.; Kumaravel, M.;
Lara, J. A.; Ganeshmurugan, S.; Bushby, L. M.; Tidey, J. P.; Blake, A. J. J. Mater. Chem.
C, 2015, 3, 6652. (d) Dou, L.; Liu, Y.; Hong, Z.; Li, G.; Yang, Y. Chem. Rev., 2015, 115,
12633.
2
Mikroyannidis, J. A.; Stylianakis, M. M.; Balraju, P.; Suresh, P.; Sharma, G. D.
ACS. Appl. Mater. Interfaces, 2009, 8, 1711 and references therein.
10

3
(a) Organic Field-Effect Transistors (Eds.: Z. Bao, J. Locklin), CRC, New York,
2007. (b) Wu, W.; Liu, Y.; Zhu, D. Chem. Soc. Rev., 2010, 39, 1489. (c) Chao, P-Y.; Wu,
H-C.; Lu, C.; Hong, C-W.; Chen, W-C. Macromolecules, 2015, 48, 5596.
4
(a) Chen, J.; Cao, Y. Acc. Chem. Res. 2009, 42, 1709. (b) Mikroyannidis, J. A.;
Kabanakis, A.; Balraju, P.; Sharma, G. D. J. Phys. Chem. C, 2010, 144, 12355. (c)
Mikroyannidis, J. A.; Tsagkournos, D. V.; Sharma, S. S.; Sharma, G. D. J. Phys. Chem.
C, 2011, 115, 7806. (d) Sharma, G. D.; Mikroyannidis, J. A.; Kurchania; Justin Thomas,
K. R. J. Mater. Chem., 2012, 22, 13986. (e) Mishra, A.; Bäuerle, P. Angew. Chem. Int.
Ed. 2012, 51, 2020. (f) Mei, J.; Diao, Y.; Appleton, A. L.; Fang, L.; Bao, Z. J. Am. Chem.
Soc., 2013, 135, 6724. (g) Kumaresan, P.; Vegiraju, S.; Ezhumalai, Y.; Yau, S. L.; Kim,
C.; Lee, W-H.; Chen, M-C. Polymers, 2014, 6, 2645. (h) Liu, X.; Kim, Y. J.; Ha, Y. H.;
Zhao, Q.; Park, C. E.; Kim, Y-H. ACS. Appl. Mater. Interfaces, 2015, 7, 8859.
5
(a) He, Y. J.; Wu, W. P.; Zhao, G. J.; Liu, Y. Q.; Li, Y. F. Macromolecules, 2008,
41, 9760. (b) Lim, B.; Baeg, K. J.; Jeong, H. G.; Jo, J.; Kim, H.; Park, J. W.; Noh, Y. Y.;
Vak, D.; Park, J. H.; Park, J. W. Kim, D. Y. Adv. Mater., 2009, 21, 2808. (c) Kim, J.;
Lim, B.; Baeg, K. J.; Noh, Y. Y.; Khim, D.; Jeong, H. G.; Yun, J. M.; Kim, D. Y. Chem.
Mater., 2011, 23, 4663. (d) Jang, S. Y.; Lim, B.; Yu, B. K.; Kim, J.; Baeg, K. J.; Khim,
D.; Kim, D. Y. J. Mater. Chem., 2011, 21, 11822
6
(a) Wudl, F.; Kobayashi, M.; Heeger, A. J. J. Org. Chem., 1984, 49, 3382. (b)
Kisselev, R.; Thelakkat, M. Macromolecules, 1998, 37, 8951. (c) Vangeneugden, D. L.;
Vanderzande, D. J. M.; Salbeck, J.; van Hal, P. A.; Janssen, R. A. J.; Hummelen, J. C.;
Brabec, C. J.; Shaheen, S. E.; Sariciftci, N. S. J. Phys. Chem. B, 2001, 105, 11106. (d)
Kisselev, R.; Thelakkat, M. Chem. Commun., 2002, 1530. (e) Meek, S. T.; Nesterov, E.
11

E.; Swager, T. M. Org. Lett., 2008, 10, 2991. (f) Raj, M. R.; Anandan, S. RSC. Adv.,
2013, 3, 14595.
7
Mohanakrishnan, A. K.; Lakshmikantham, M. V.; McDougal, C.; Cava, M. P.;
Baldwin, J. W.; Metzger, R. M. J. Org. Chem., 1998, 63, 3105.
Raj, M. R.; Anandan, S.; Solomon, R. V.; Venuvanalingam, P.; Iyer, S. K.;
Ashokkumar, M. J. Photochem. Photobiol. A, 2013, 262, 34.
(a) Friend, R. H.; Gymer, R. W.; Holmes, A. B.; Burroughes, J. H.; Marks, R. N.;
8
9
Taliani, C.; Bradley, D. D. C.; Dos Santos, D. A.; Brédas, J.; Löglund, M.; Salaneck, W.
R. Nature, 1999, 397, 121. (b) Data, P.; Motyka, R.; Lapkowski, M.; Suwinski, J.;
Monkman, A. P. J. Phy. Chem. C, 2015, 119, 20188. (c) Asano, M. S.; Kagota, D.;
Haque, T.; Koinuma, M.; Inagaki, A.; Nomura, K. Macromolecules, 2015, 48, 6233.
10
11
Figueira-Duarte, T. M.; Müllen, K. Chem. Rev., 2011, 111, 7260.
Singh, H.; Balamurugan, A.; Jayakannan, M. ACS. Appl. Mater. Interfaces, 2013,
5, 5578.
12
Liu, B.; Najari, A.; Pan, C.; Leclerc, M.; Xiao, D.; Zou, Y. Macromol. Rapid
Commun., 2010, 31, 391.
13
(a) Amaladass, P.; Arul Clement, J.; Mohanakrishnan, A. K. Eur. J. Org. Chem.,
2008, 3798. (b) Senthil Kumar, N.; Mohanakrishnan, A. K. Tetrahedron, 2010, 66, 5660.
(c) Sivasakthikumaran, R.; Arul Clement, J.; Nandakumar, M.; Mohanakrishnan, A. K. J
Heterocyclic Chem, 2015, DOI: 10.1002/jhet.2448.
14
(a) Gobi Rajeshwaran, G.; Nandakumar, M.; Sureshbabu, R.; Mohanakrishnan, A.
K. Org. Lett., 2011, 13, 1270. (b) Gobi Rajeshwaran, G.; Mohanakrishnan, A. K. Org.
12

Lett., 2011, 13, 1418. (c) Raju, P.; Gobi Rajeshwaran, G.; Nandakumar, M.;
Mohanakrishnan, A. K. Eur. J. Org. Chem., 2015, 3513.
15
Kumari, N.; Dey, N.; Jha, S.; Bhattacharya, S. ACS. Appl. Mater. Interfaces,
2013, 5, 2438.
16
(a) Egbe, D. A. M.; Tillmann, H.; Birckner, E.; Klemm, E. Macromol. Chem.
Phys., 2001, 202, 2712. (b) Shao, H.; Chen, X.; Wang, Z.; Lu, P. J. Phys. Chem. B, 2007,
111, 10386.
17
(a) Figueira-Duarte, T. M.; Simon, S. C.; Wagner, M.; Druzhinin, S. I.;
Zachariasse, K. A.; Müllen, K. Angew. Chem. Int. Ed., 2008, 47, 10175. (b) Figueira-
Duarte, T. M.; Müllen, K. Chem. Rev., 2011, 111, 7260. (c) You, J.; Li, G.; Wang, R.;
Nie, Q.; Wang, Z.; Li, J. Phys. Chem. Chem. Phys., 2011, 13, 17825. (d) Feng, X.; Seto,
N.; Wang, C.-Z.; Matsumoto, T.; Tanaka, J.; Wei, X.-F.; Elsegood, M. R. J.; Horsburgh,
L.; Redshaw, C.; Yamato, T. ChemistrySelect 2016, 1, 1926.
13

Scheme I. Decarbonylation of benzo[c]thiophenyl aldehyde 1.
14

Scheme II. Synthesis of Benzo[c]thiophenyl phosponate ester using room temperature
Michaelis-Arbuzov reaction
15

Scheme III. Synthesis of benzo[c]thiophenyl vinylenes BT-BT and BT-EDOT
16

Scheme IV. Synthesis of phosponate ester 11 and vinylenes PP-TT, PP-PY & PP-TPA
17

Scheme V. Synthesis of phosphonate ester 16
18

Scheme VI. Synthesis of vinylenes PY-TPA and PY-EDOT
19

Scheme VII. Synthesis of vinylenes PY-PY and PY-PVPY
20

Scheme VIII. Photophysical properties of synthesized vinylenes
21

Figure I. Absorption and luminescence spectra of vinylenes BT-BT and BT-EDOT.
22

Figure II. Absorption and luminescence spectra of vinylenes PP-TT, PP-PY and PP-
TPA.
23

Figure III. Absorption and Luminescence spectra of vinylene PY-TPA, PY-EDOT, PY-
PY and PY- PVPY.
24