Synthesis, characterization, and electronic properties of novel Fc-DCM conjugated system; Experimental and computational studies

Article abstract of DOI:10.1016/j.jorganchem.2016.03.007

Novel Fc-DCM conjugated compound, 2-(2-ferrocenylvinyl-6-methyl-4H-pyran-4-ylidine) malononitrile, in the form of donor-spacer-acceptor dyad has been synthesized by Knoevenagel condensation. ¹H and ¹³C NMR, FT-IR, CHN analysis and along with atomic absorption spectroscopy supported the predicted structure of the product. The electrochemical behaviour of synthesized compound and the electronic absorption spectra were studied in a variety of solvents. Extensive calculations with various combinations of functionals were carried out to compute energy gap (Eg) of ferrocene derivative. The combined functional and basis set approach PBE/6-31+G(d,p) was found to be well-behaved in the calculation of energy gap. B3LYP/6-31G(d) method was applied to do TD-DFT calculations due to its good agreement with experimental data for prediction of UV-Vis spectra.

Full text of DOI:10.1016/j.jorganchem.2016.03.007

Accepted Manuscript
Synthesis, characterization, and electronic properties of novel Fc- DCM conjugated
system; experimental and computational studies
Reza Teimuri-Mofrad, Keshvar Rahimpour, Rahim Ghadari
PII:
S0022-328X(16)30083-3
10.1016/j.jorganchem.2016.03.007
JOM 19432
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 7 January 2016
Revised Date: 24 February 2016
Accepted Date: 8 March 2016
Please cite this article as: R. Teimuri-Mofrad, K. Rahimpour, R. Ghadari, Synthesis, characterization,
and electronic properties of novel Fc- DCM conjugated system; experimental and computational studies,
Journal of Organometallic Chemistry (2016), doi: 10.1016/j.jorganchem.2016.03.007.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to
our customers we are providing this early version of the manuscript. The manuscript will undergo
copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please
note that during the production process errors may be discovered which could affect the content, and all
legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
Synthesis, characterization, and electronic properties of novel Fc- DCM
conjugated system; experimental and computational studies
Reza Teimuri-Mofrad *, Keshvar Rahimpour, Rahim Ghadari
Department of Organic and Biochemistry, Faculty of Chemistry, University of Tabriz, 51664 Tabriz, Iran
Corresponding author Tel.: +98 41 33393105; Fax: +98 411 3340191
E-mail address: teymouri@tabrizu.ac.ir (R. Teimuri-Mofrad)
Abstract
Novel Fc-DCM conjugated compound, 2-(2-ferrocenylvinyl-6-methyl-4H-pyran-4-ylidine)
malononitrile, in the form of donor–spacer–acceptor dyad has been synthesized by Knoevenagel
1
condensation. H and 13C NMR, FT-IR, CHN analysis and along with atomic absorption
spectroscopy supported the predicted structure of the product. The electrochemical behaviour of
synthesized compound and the electronic absorption spectra were studied in a variety of solvents.
Extensive calculations with various combinations of functionals were carried out to compute
energy gap (Eg) of ferrocene derivative. The combined functional and basis set approach PBE/6-
31+G(d,p) was found to be well-behaved in the calculation of energy gap. B3LYP/6-31G(d)
method was applied to do TD-DFT calculations due to its good agreement with experimental
data for prediction of UV-Vis spectra.
Keywords: Ferrocene, Knoevenagel condensation, Cyclic Voltammetry
1-Introduction
Donor–Spacer–Acceptor (DSA) dyads in the forms of both discrete molecules [1] and polymers
[2] attract a great deal of scientific and commercial interest. The intramolecular charge transfer
(ICT) process in these compounds continues to be a topic of extensive experimental [3] and
theoretical [4] studies. Low molecular mass organic compounds with internal charge transport
properties are widely adopted in such cases because of their potential applications in optical,
electronic and magnetic materials [5], thin film transistors [6], sensors [7], organic light emitting
diodes (OLEDs) [8], dye sensitized solar cells (DSSCs) [9], solid state lasers and photovoltaic
cells [10]. In the last decade, (OLEDs) have attracted considerable attention due to their useful
application in full colour displays. Many scientific research have been focused on the
developments in sets of the primary colour emitters of red, green and blue (RGB) [11].
One of the most notable red luminescent materials contains 2,6-dimethyl-4H-pyran-4-ylidene
fragment as the backbone of molecule. In general, the pyran-4-ylidene has the structure of
electron donor-acceptor with a narrow band gap. In DSA type dyads, the structure of π-
conjugated spacer plays an important role in charge transfer process. Compounds with extended
conjugated π-electron systems are very common for the fabrication of several optical devices.
1

ACCEPTED MANUSCRIPT
Pyran and its substituted derivatives are easy to modify and a large number of them are
commercially available [12].
Among many kinds of donor groups ferrocene and its derivatives have been extensively studied
to be used in molecular wire and nonlinear optical materials. ferrocene and its derivatives have
found many applications in materials science including catalysts [13], medicines [14], sensors
[15], aerospace materials [16], and electro active materials [17] which could be well
corresponded to the favourable electronic properties of the compounds mentioned above.
A suitable combination of the structural features of two small organic or organometallic
molecules may result in the creation of new molecules, which could improve the properties
which make the new compound to be more efficacious and economical.
In this work, in continuance of our previous studies on various synthesis of ferrocene containing
materials, 2-(2-ferrocenylvinyl-6-methyl-4H-pyran-4-ylidene) malononitrile has been designed
and synthesized through Knoevenagel condensation of ferrocenecarboxaldehyde and 2-(2, 6-
dimethyl-4H-pyran-4-ylidine) malononitrile. Furthermore, its electrochemical and photochemical
properties are studied in different solutions. To analyse the observed spectra, time dependent
density functional theoretical (TD-DFT) computation was performed at B3LYP/6-31G(d) level
of theory by the Gaussian 09 program. Various methods and basis sets were used for single-point
calculation to predict the energy gap. Finally PBE/6-31+G(d, p) method gave the most accurate
data for energy gap; therefore, band gap energies were calculated via this method for ferrocene
compound in different solvents.
2-Results and discussion
Due to interesting electronic properties of ferrocene and its derivatives, it was decided to use this
popular molecule for the synthesis of novel Fc-DCM conjugated compound. Generally,
Knoevenagel condensation is considered as a convenient route for the preparation of these types
of compounds with extended π-electron conjugation. Since the derivatives of 4-substituted 4H-
pyran-4-one could be easily obtained by condensation of 2, 6-dimethyl-4H-pyran-4-one with
active methylene groups, the 2-(2,6-dimethyl-4H-pyran-4-ylidene) malononitrile was chosen as
the starting material for Knoevenagel condensation with ferrocenecarboxaldehyde.
Ferrocene was put in to reaction with N-methylformanilide and phosphoryl chloride to
synthesize ferrocenecarboxaldehyde through Vilsmeier reaction which was done according to the
modified procedure described by Graham and co-workers in 71% [18].
The final product, 2-(2-ferrocenylvinyl-6-methyl-4H-pyran-4-ylidine) malononitrile (Scheme 1),
in the form of donor–spacer–acceptor dyad was obtained in a considerably good yield by
Knoevenagel condensation of 2-(2,6-dimethyl-4H-pyran-4-ylidene) malononitrile with
1
13
ferrocenecarboxaldehyde. The elemental analyses, mass spectra, FT-IR, H NMR and C NMR
1
spectra all well confirmed the predicted molecular structure. In H NMR spectra, the aldehyde
2

ACCEPTED MANUSCRIPT
3
peaks disappeared at around 10 ppm, while in 6.29 and 7.31 ppm the doublet peaks with J =
15.8 Hz were appeared obviously which could be related to -HC=CH- protons. In infrared
spectra, the absorptions at 2206 cm-1 and 1303 cm-1 were assigned to the stretching of cyanide
and the vibration of C-O bond of pyran moiety, respectively.
Scheme 1. Synthesis of Fc-DCM by Knoevenagel condensation
The UV-Vis absorption spectra of ferrocene dyads were measured in different solvents with
different polarities (5×10-5 M) (Fig 1).
[Fig 1]
In the spectrum of Fc-DCM compound, there are two characteristic transitions (λmax) whose
position vary in different solvents. The values of lower wavelengths vary between 345 and 402
nm and it has been assigned to π-π* transition; another one is located at a longer wavelengths
and the maximum absorption values differ from 520 to 529 nm; this absorption is due to metal-
to-ligand charge transfer (MLCT) and finally no absorption observed for d-d transition unless it
is covered by the broad MLCT band (Table 1). The two bands are influenced by the polarity of
the solvent (Fig 2).
[Fig 2]
[Table 1]
Both transitions showed an unusual small negative solvatochromism with the increasing of
solvent polarity which could be assumed to be due to the contribution of the resonance hybrid to
the excited state. In addition, these different shifts are not attributed to the solvent polarity alone,
but also the interaction of the solute/solvent is effective as well. The experimental band gap
energies were calculated (Table 2) according to Eq. (1) [19]:
Eg = 1240/ λ
(1)
The wavelength at the absorption edge, λ, was determined as the intercept on the wavelength axis
for a tangential line drawn on the absorption spectra (Fig 3).
[Fig 3]
[Table 2]
3

ACCEPTED MANUSCRIPT
The electrochemical property of Ferrocene derivative was measured by cyclic voltammetry (CV)
using a 0.1 M solution of tetrabutylammonium perchlorate (TBAP) in anhydrous
dichloromethane, chloroform and diethylether, in acetone and acetonitrile lithium perchlorate
were used as supporting electrolyte. Representative CVs of Fc-DCM are presented in Fig 4. The
CV data gives valuable information about the oxidation and reduction potentials of materials. In
all solvents, a single redox process, showed a reversible voltammetric behaviour for the
ferrocenyl group in these compounds with ∆Ep = Epa - Epc ≤ 0.08 V at 0.50 V. s-1 scan rates.
The oxidation corresponds to electron extraction from the HOMO level and can be correlated to
the ionization potential, whereas the reduction potential is associated with electron affinity and
Indicates that the LUMO level. These processes could be scaled using CV method by measuring
the redox potentials. The HOMO energy levels were calculated using equation 2, where Eox and
Eferrocene are the onset oxidation potentials for the dyad sample and the ferrocene against Ag/AgCl
reference electrode, while the value – 4.8 eV is the HOMO energy level of ferrocene against
vacuum.
[Fig 4]
The LUMO energy levels were calculated with the HOMO levels attained via by CV
measurements and the optical band gap (Eg) obtained by UV-Vis measurements, equation 3 [20].
E
HOMO = - [Eox + 4.8 - Eferrocene
]
(2)
(3)
ELUMO = EHOMO + Eg
The onset potentials of oxidation are determined from intersection of the tangents between the
baseline and the signal current. The onset potentials of ferrocene oxidation vs. Ag/AgCl are
reported as following: 0.49, 0.52, 0.53, 0.42 and 0.27, in diethyl ether, CH2Cl2, CHCl3, acetone,
acetonitrile respectively.
In continue, computational approaches were used to further analyse the observed optical and
electrochemical properties. The energies of the frontier orbitals, the highest occupied molecular
orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), were calculated with
various methods and basis sets using Gaussian 09 program in gas phase (Fig 5). The results are
summarized in Table 3. From the results presented in Table 3, it is clear that the PBE/6-31+G(d,
p) method gives more accurate data for energy gap calculations and therefore it was chosen for
further calculation on band gap energies of Fc-DCM compound in different solvents with
increasing polarity. The results are in good agreement with experimental data that obtained from
UV-Vis and CV spectra (Table 4). Different levels of theories have been used to simulate the
observed UV-Vis spectra. After all, it has been found that the B3LYP/6-31G(d) method is the
most suitable one to predict the observed λmax. The results of these studies have been
summarized in Table 2.
4

ACCEPTED MANUSCRIPT
[Fig 5]
[Table 3]
[Table 4]
Good consistency between experimental and calculated data indicates that these functionals are
reliable in predicting the electronic properties of ferrocene derivatives.
Fig 6 shows the energy levels diagram of the materials, which is usually utilized to fabricate the
electroluminescent devices. 4-(Dicyanomethylene)-2-methyl-6-[(dimethylamino)styryl]-4H-
pyran (DCM) is a well- known red dopant that was used as a reference and the data for DCM,
tris(4-(2-phenylethynyl)phenyl)amine (TPA), tris(8- quinolinolato)aluminum (Alq3), indium tin
oxide (ITO) and LiF/Al were cited from the literature [21]. HOMO and LUMO energy levels of
Fc- DCM which were calculated at PBE/6-31+G(d, p) method in gas phase, revealed to fall
between those of TPA and therefore, energy can easily be transferred from TPA to Fc- DCM.
The LUMO of Alq3 is equal to that of Fc- DCM and HOMO of Alq3 is lower than HOMO of
DCM. Energy level matching between dopant and host materials indicates that our synthetic
dyad has the potential to be used in the fabrication of electroluminescent devices as dopants.
[Fig 6]
3-Conclusion
In summary, the design and synthesis of novel Fc-DCM conjugated compound, 2-(2-
ferrocenylvinyl-6-methyl-4H-pyran-4-ylidene) malononitrile, by Knoevenagel condensation of
ferrocenecarboxaldehyde and 2-(2, 6-dimethyl-4H-pyran-4-ylidine) malononitrile, has been done
1
successfully in the present research. H and 13C NMR, FT-IR, CHN analysis, and atomic
absorption spectroscopy supported the predicted structure of the product. The electrochemical
behaviour of Fc-DCM compound and the electronic absorption spectra was studied in variety of
solvents. Extensive single-point calculations with various combinations of functionals are carried
out to compute energy gap (Eg) of the ferrocene derivative. The PBE/6-31+G(d,p) level of
theory was found to be well-behaved in the calculation of energy gap. B3LYP/6-31G(d) method
was applied to accomplish the TD-DFT calculations due to its good agreement with experimental
data for prediction of UV-Vis spectra.
4-Experimental
4.1. Materials and Instrumentation
Solvents and reagents were purchased from Merck, Fluka, Aldrich and Yantai Suny Chem.
International Co., Ltd. Commercial compounds were used without any kind of purification.
5

ACCEPTED MANUSCRIPT
1
13
The H and C NMR spectra were recorded with a Bruker FT-400 MHz spectrometer at 300 K
and with CDCl3 as solvent. The FT-IR spectra were recorded on a Bruker-Tensor 270
spectrometer. Elemental analyses were carried out with an Elementor Vario EL. III instrument.
Iron analysis was performed by Analytikjene (novaa 400) atomic absorption spectrophotometer.
The electronic absorption spectra were obtained using SPECORD 250 analytikjena UV/Vis
spectrophotometer.
Cyclic voltammetry measurements were performed on 1 mM solutions of ferrocene derivative in
different organic solvents (dichloromethane, chloroform, diethyl ether, acetone and acetonitrile)
in the presence of 0.100 M Bu4N(ClO4) and LiClO4 as supporting electrolytes using
potentiostat/galvanostat Autolab (PGASTAT 30) equipped with a standard three-electrode cell.
A 2-mm-diameter GC was used as the working electrode. A silver/silver chloride (Ag/AgCl)
electrode and a platinum electrode were used as the reference and the counter electrodes,
respectively. All potentials in this study are reported with respect to the Ag/AgCl.
4.2. Theoretical Methods
All calculations were carried out through the Gaussian 09 (Rev. D.01) [22] program package by
using density functional theory (DFT) and time-dependent DFT (TD-DFT). The frontier orbital
energies were predicted with various methods. The functionals used in single-point calculations
were B3LYP [23], BLYP [24], HF [25], MP2 [26], M06-2X [27], and PBE [28]. The basis set
used were defined as 6-31G(d), 6-31G(d,p), 6-31+G(d,p), 6-31++G(d,p), 6-31G(d), 6-
311+G(d,p), and 6-311++G(d,p) [29]. Structure of novel compound was optimized in the gas-
phase. For geometry optimizations, the B3LYP level of theory with the 6-311++G(d,p) basis
set was employed and no symmetry constraints were imposed. Frequency calculation was done
on the optimized structure to ensure the minima nature of the optimized structure by the absence
of the imaginary frequency. TD-DFT calculations were performed on the optimized structure to
obtain the λmax values. The TDDFT calculations were carried out in gas-phase and in the
presence of different solvents using polarizable continuum model (PCM) for the solvents.
4.3. Synthesis of Fc-DCM
Both ferrocenecarboxaldehyde [18] and 2-(2, 6-methyl-4H-pyran-4-ylidene) malononitrile [30]
were prepared according to the reference method. A solution of 2-(2, 6-methyl-4H-pyran-4-
ylidine) malononitrile (1) (0.14 g, 1.40 mmol), ferrocenecarboxaldehyde (2) (0.20 g, 1.40 mmol)
and piperidine (1 mL) in dry acetonitrile (10 mL) was refluxed for 24 hours under argon
atmosphere. A red fluorescent colour was observed all along the reaction. The reaction was
controlled with TLC method by monitoring the compound 1 in the solution of reaction. After the
completion of the reaction, the solution was cooled to room temperature and the product was
purified using liquid column chromatography over silica gel and hexane: EtOAc (8:2) as eluent.
0.24 g dark red solid was obtained (63% yield), FT-IR (KBr, cm-1): 3115 (Cp-H), 2205 (C≡N),
1690, 1509 (C=C), 1048(Cp); 1H NMR (CDCl3, 400 MHz) δ: 7.31 (d, 3J = 15.80 Hz, 1H, =CH ),
3
6.52 and 6.56 (s, 2H, pyran), 6.29 (d, J = 15.80 Hz, 1H, =CH), 4.53 (t, 2H, C5H4), 4.50 (t, 2H,
6

ACCEPTED MANUSCRIPT
13
C5H4), 4.19 (s, 5H, C5H5), 2.39 (s, 3H, CH3); C NMR (CDCl3, 100 MHz) δ: 160.74, 158.45,
155.51, 138.64, 138.17, 105.21, 104.15, 78.32, 70.39, 69.21, 68.75, 67.30, 18.91; Anal. Found:
C, 68.42; H, 4.32; Fe, 15.13; N, 7.56 .Calc. for: C21H16FeN2O: C, 68.50; H, 4.38; Fe, 15.17; N,
7.61%.
Acknowledgment
We gratefully acknowledge the financial support for this work by the Research Council of
University of Tabriz.
References
[1] (a) B. Balaganesan, S. W. Wen, C. H. Chen, Tetrahedron Letters, 44 (2003) 145-147;
(b) L. Cosimbescu, L. Wang, M. L. Helm , E. Polikarpov, J. S. Swensen, A. B. Padmaperuma,
International Journal of Organic Chemistry, 2 (2012), 101-110;
(c) R. W. Sinkeldam, N. J. Greco, Y. Tor, Chem. Rev., 110 (2010), 2579-2619;
(d) Y. B. Wu, H. M. Guo, T. D. James, J. Z. Zhao, J. Org. Chem., 76 (2011), 5685-5695.
[2] (a) J. H. Kim, H. Lee, Chem. Mater., 14 (2002), 2270-2275;
(b) B.Y. Hsieh, Y. Chen, Macromolecules, 40 (2007), 8913-8923;
(c) G. W. Kim, M. J. Cho, Y. Yu, Z. H. Kim, J. Jin, D. Y. Kim, D. H. Choi, Chem. Mater., 19
(2007), 42-50;
(d) Z. Guo, W. Zhu, H. Tian, Chem. Commun., 48 (2012), 6073-6084.
[3] (a) P. J. Kim, O. P. Kwon, M. Jazbinsek, H. Yun, P. Günter, Dyes and Pigments, 86 (2010),
149-154;
(b) C. Jianzhong, H. J. Suh, S. H. Kim, Dyes and Pigments, 68 (2006), 75-77;
(c) S. Wang, S. H. Kim, Current Applied Physics, 9 (2009), 783-788.
[4] (a) P. Zhao, H. Tang, Q. Zhang, Y. Pi, M. Xu, R. Sun, W. Zhu, Dyes and Pigments, 82
(2009), 316-321;
(b) Y. Li, J. Yao, C. Liu, C. Yang, Journal of Molecular Structure: THEOCHEM, 867 (2008),
59-63;
(c) Y. L. Li, L. Han, Y. Mei, J. Z. H. Zhang, Chemical Physics Letters, 482 (2009), 217-222;
(d) F. Ding, S. Chen, H. Wang, Materials, 3 (2010), 2668-2683;
(e) J. Schäfer, M. Scheurer, B. Speiser, W. Kuz´nik, I.V. Kityk, Spectrochimica Acta Part A:
Molecular and Biomolecular Spectroscopy, 95 (2012), 193-198.
[5] (a) R. L. Carroll, C. B. Gorman, Angew. Chem., Int. Ed. 41 (2002), 4378-4400;
(b) A. Nitzan, M. A. Ratner, Science, 300 (2003), 1384-1389;
(c) A. Elangovan, K. M. Kao, S. W. Yang, Y. L. Chen, T. I. Ho, O. Y. Su, J. Org. Chem. 70
(2005), 4460-4469;
(d) J. A. Marsden, J. J. Miller, L. D. Shirtcliff, M. M. Haley, J. Am. Chem. Soc., 127 (2005),
2464-2476.
[6] A. Heeger, J. Chem. Soc. Rev., 39 (2010), 2354-2371.
[7] W. Samuel, III. Thomas D. J. Guy, M. S. Timothy, Chem. Rev. 107 (2007), 1339-1386.
[8] (a) A. Vembris , E. Zarins, J. Jubels, V. Kokars, I. Muzikante, A. Miasojedovas, S. Jursenas,
Optical Materials, 34 (2012), 1501-1506;
(b) C.J. Huang, , C.C. Kang , T.C. Lee, W.R. Chen, T.H. Meen, Journal of Luminescence,
129 (2009), 1292-1297;
(c) H. Fukagawa , K. Watanabe, S. Tokito, Organic Electronics, 10 (2009), 798-802.
7

ACCEPTED MANUSCRIPT
[9] (a) A. Mishra, M. K. R. Fischer, P. Bäuerle, Angew. Chem., Int. Ed. 48 (2009), 2474-2499;
(b) J. N. Clifford, M. Planells, E. Palomares, J. Mater. Chem., 22 (2012), 24195-24201.
[10] (a) C. J. Brabec, N. S. Sariciftci, J. C. Hummelen, AdV. Funct. Mater, 11 (2001), 15-26;
(b) S. A. Jenekhe, S. Yi, Appl. Phys. Lett., 77 (2000), 2635-2637.
[11] K. H. Lee, S. M. Kim, J. Y. Kim, Y. K. Kim, S. S. Yoon, Bull. Korean Chem. Soc. 31
(2010), 2889-2892.
[12] (a) M. Ghandi, Y. Bayat, R. Teimuri-mofrad, OPPI BRIEFS, 34 (2002), 489-497;
(b) B. J. Jung, J. I. Lee, H. Y. Chu, L. M. Do, J. Lee, H. K. Shim, J. Mater. Chem., 15
(2005), 2470-2475.
[13] (a) E.W. Neuse, Adv. Macromol. Chem., 1 (1968), 1;
(b) E.W. Neuse, J. R. Woodhouse, G. Montaudo, C. Puglisi, Appl. Organomet. Chem. 2
(1988), 53-57;
(c) C. Ornelas, New J. Chem., 35 (2011), 1973-1985.
[14] (a) E.A. Hillard, A. Vessie`res, G. Jaouen, Top. Organomet. Chem, 32 (2010), 81-117;
(b) L.V. Snegur, V.N. Babin, A.A. Simenel, Y.S. Nekrasov, L.A. Ostrovskaya, N.S.
Sergeeva, Russ. Chem. Bull. Int. Ed, 59 (2010), 2167-2178.
[15] (a) R. Sun, L. Wang, H. Yu, Z. Abdin, Y. Chen, J. Huang, R. Tong, Organometallics, 33 (18)
(2014), 4560–4573;
(b) M. Saleem, H. Yu, , L. Wang, , Z. Abdin, H. Khalid, M. Akram, N. M. Abbasi, J. Huang,
Analytica Chimica Acta, 876 (2015), 9-25.
[16] (a) D. Saravanakumar, N. Sengottuvelan, V. Narayanan, M. Kandaswamy, T. L. VargheseJ.
Journal of Applied Polymer Science, 119 (2011), 2517-2524;
(b) K. Subramanian, Journal of Polymer Science: Part A: Polymer Chemistry, 37(1999),
4090-4099.
[17] (a) V. Wei, R. Vajtai, Y.Y. Choi, P.M. Ajayan, H. Zhu, C. Xu, D. Wu, Nano Lett., 2 (2002),
1105-1107;
(b) A.K. Diallo, C. Ornelas, L. Salmon, J.R. Aranzaes, D. Astruc, Angew. Chem. Int. Ed, 46
(2007), 8644-8648.
[18] P. J. Graham, R. V. Lindsey, G. W. Parshall, M. L. Peterson, G. M. Whitman, J. Am.
Chem.Soc., 79 (1957), 3416-3420.
[19] D.S. Bhatkhande, V.G. Pangarkar, A.A. Beenackers, J. Chem. Technol. Biotechnol, 77
(2001), 102-116.
[20] H. Liu, R. Bo, H. Liu, N. Li, Q. Xu, H. Li, J. Lu, L. Wang, J. Mater. Chem. C, 2 (2014),
5709-5716.
[21] Y. S. Yao, J. Xiao, X. S. Wang, Z. B. Deng, B. W. Zhang, Adv. Funct. Mater, 16 (2006),
709-718.
[22] Gaussian 09, Revision A.02, M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M.
A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A. Petersson, H.
Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, J. L.
Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T.
Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J. A. Montgomery, Jr., J. E. Peralta, F.
Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov, R.
Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J.
Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene, J. E. Knox, J. B. Cross, V. Bakken, C.
8

ACCEPTED MANUSCRIPT
Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C.
Pomelli, J. W. Ochterski, R. L. Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P.
Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels, O. Farkas, J. B. Foresman, J. V.
Ortiz, J. Cioslowski, and D. J. Fox, Gaussian, Inc., Wallingford CT, 2009.
[23] A.D. Becke, J. Chem. Phys, 98 (1993), 5648-5652.
[24] A. D. Becke, Phys. Rev. A, 38 (1988), 3098-3100.
[25] C. C. J. Roothaan, Rev. Mod. Phys., 23 (1951), 69-89.
[26] M. Head-Gordon, J. A. Pople, and M. J. Frisch, Chem. Phys. Lett., 153 (1988), 503-506.
[27] Y. Zhao and D. G. Truhlar, Theor. Chem. Acc., 120 (2008), 215-241.
[28] J.P. Perdew, K. Burke and M. Ernzerhof, Phys. Rev. Lett., 77 (1996), 3865-3868.
[29] (a) R. Ditchfield, W. J. Hehre, J. A. Pople, J. Chem. Phys., 54 (1971), 724-728;
(b) W. J. Hehre, R. Ditchfield, J. A. Pople, J. Chem. Phys., 56 (1972), 2257-2261;
(c) P. C. Hariharan, J. A. Pople, Theor. Chem. Acc., 28 (1973), 213-22;
(d) P. C. Hariharan, J. A. Pople, Mol. Phys., 27 (1974), 209-214;
(e) M. S. Gordon, Chem. Phys. Lett., 76 (1980), 163-168;
(f) M. M. Francl, W. J. Pietro, W. J. Hehre, J. S. Binkley, D. J. DeFrees, J. A. Pople, and M.
S. Gordon, J. Chem. Phys., 77 (1982), 3654-3665;
(g) A.D. McLean, G.S. Chandler, J. Chem. Phys., 72 (1980), 5639-5648.
[30] D.U. Kim, S.H. Paik, S.H. Kim, Y.H. Tak, Y.S. Han, S.D. Kim, K.B. Kim, H.J. Ju, T.J.
Kim, Mater. Sci. Eng: C, 24 (2004), 147-153.
9

ACCEPTED MANUSCRIPT
Fig 1. Normalized UV-Vis absorption of Fc-DCM in different solvents
Fig 2. MLCT and π→π* transition in different solvents
10

ACCEPTED MANUSCRIPT
Fig 3. The band gap calculation using UV-Vis spectra.
Fig 4. Representative CVs of Fc-DCM (1×10-3 M) in CH3CN/0.100 M LiClO4 at 50 mV s-1 vs.
Ag/AgCl.
11

ACCEPTED MANUSCRIPT
Fig 5. the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular
orbital (LUMO) for Fc-DCM
12

ACCEPTED MANUSCRIPT
Fig 6. Schematic energy- level diagram of red OLED
13

ACCEPTED MANUSCRIPT
Table 1. Absorption spectral data of Fc-DCM in various solvents.
λmax
Solvent
π→π*
399
MLCT
520
Diethyl ether (34.5)a
Dichloromethane (40.7)
Chloroform (39.1)
Acetone (42.2)
402
529
411
538
401
401
526
525
Acetonitrile (45.6)
a The solvent parameters ET in kcal.mol-1
Table 2. HOMO and LUMO energy levels obtained from DFT calculations and experiment,
where solvent is specified.
Diethyl ether
-4.71
Dichloromethane
Chloroform
-4.70
Acetone
-4.64
-4.88
-3.20
-2.89
1.44
Acetonitrile
-4.63
HOMO (DFT)
HOMO (experiment CV)
LUMO (DFT)
-4.66
-4.88
-3.21
-2.91
1.45
-4.89
-4.87
-4.88
-3.22
-3.22
-3.19
LUMO (experiment CV)
Eg (TDDFT)
-2.89
-2.90
-2.89
1.49
1.48
1.44
Eg (experiment UV–Vis)
2.00
1.97
1.98
1.96
1.97
14

ACCEPTED MANUSCRIPT
Table 3. Energies of the Frontier Molecular Orbitals HOMO and LUMO in gas phase.
B3LYP
-5.66
BLYP
-4.31
HF
MP2
-8.12
M06-2X
-7.12
PBE
HOMO (eV)
LUMO (eV)
-8.12
-4.53
6-31G*
-2.37
-2.65
0.92
0.92
-1.63
-2.89
HOMO - LUMO
3.29
1.66
9.04
9.04
5.49
1.64
HOMO (eV)
-5.66
-5.66
-8.11
-8.11
-7.11
-4.53
6-31G**
LUMO (eV)
-2.37
-2.37
0.92
0.92
-1.63
-2.90
HOMO - LUMO
3.29
3.29
9.03
9.03
5.48
1.63
HOMO (eV)
-5.66
-4.67
-8.27
-8.27
-7.34
-4.83
6-31+G**
LUMO (eV)
-2.37
-3.01
0.43
4.27
-1.89
-3.19
HOMO - LUMO
3.29
1.66
8.7
12.54
5.45
1.69
HOMO (eV)
-5.96
-4.67
-8.27
-8.27
-7.34
-4.87
6-31++G**
6-311G*
LUMO (eV)
-2.68
-3.01
0.34
0.34
-1.90
-3.24
HOMO - LUMO
3.28
1.66
8.61
8.61
5.44
1.63
HOMO (eV)
-5.92
-4.60
-8.25
-8.25
-7.33
-4.78
LUMO (eV)
HOMO - LUMO
HOMO (eV)
-2.61
3.31
-2.93
1.67
0.76
9.01
-8.30
0.76
9.01
-8.30
-1.85
5.48
-3.12
1.66
-6.02
-4.72
-7.41
-4.88
6-311+G**
LUMO (eV)
-2.73
-3.07
0.42
0.42
-1.95
-3.24
HOMO - LUMO
3.29
1.65
8.72
8.72
5.46
1.64
HOMO (eV)
-6.02
-4.72
-8.30
-8.30
-7.40
-4.88
6-311++G**
LUMO (eV)
-2.73
-3.07
0.33
0.33
-1.95
-3.24
HOMO - LUMO
3.29
1.65
8.33
8.63
5.45
1.64
15

ACCEPTED MANUSCRIPT
Table 4. Calculated lowest-energy absorption maxima for Fc-DCM. The theoretical oscillator
strength (f) and the experimental extinction coefficient (ε)
Theory
λ max (nm)
Experiment
f
λ max (nm)
Ε
Diethyl ether
389
346
0.8653
399
402
28640
Dichloromethane
1.0594
0.8861
43068
29476
Chloroform
391
411
Acetone
391
391
0.8331
0.8228
401
401
29868
28164
Acetonitrile
16

ACCEPTED MANUSCRIPT
Highlights
•
•
•
•
•
2-(2-Ferrocenylvinyl-6-methyl-4H-pyran-4-ylidine) malononitrile, in the form of donor–
spacer–acceptor dyad were synthesized.
The electrochemical behaviour of synthesized compound and the electronic absorption
spectra were studied in a variety of solvents.
Extensive calculations with various combinations of functionals were carried out to
compute energy gap of novel dyad.
The combined functional and basis set approach PBE/6-31+G(d,p) was found to be well-
behaved in the calculation of energy gap.
B3LYP/6-31G(d) method was applied to do TD-DFT calculations due to its good
agreement with experimental data for prediction of UV-Vis spectra.