Investigation of charge-transfer interaction in mixed stack donor? Acceptor cocrystals toward tunable solid-state emission characteristics

Article abstract of DOI:10.1021/acs.cgd.8b00852

The formation of three mixed binary charge transfer (CT) cocrystals with tunable photoluminescence behavior featuring both CT interaction and directional hydrogen bonding is presented. Our strategy consists of the CT induced cocrystallization of three pol

Full text of DOI:10.1021/acs.cgd.8b00852

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Article
Investigation of Charge-Transfer Interaction modes in Mixed Stack Donor-
Acceptor Cocrystals Towards Tunable Solid-State Emission Characteristics
Rabia Usman, Arshad Khan, Mingliang Wang, Yi Luo, Weiwei Sun, Hao Sun, Cunbin Du, and Nongyue He
Cryst. Growth Des., Just Accepted Manuscript • DOI: 10.1021/acs.cgd.8b00852 • Publication Date (Web): 07 Sep 2018
Downloaded from http://pubs.acs.org on September 11, 2018
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Investigation of ChargeꢀTransfer Interaction modes in Mixed Stack Donorꢀ
Acceptor Cocrystals Towards Tunable SolidꢀState Emission Characteristics
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a
b
a
c
d,e
a
†
†
Rabia Usman , Arshad Khan , Mingliang Wang* , Yi Luo , Weiwei Sun , Hao Sun , Cunbin
Dua, Nongyue He*b
a
School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, P. R.
China
b State Key Laboratory of Bioelectronics, Southeast University, Nanjing 210096, P. R. China
c Jiangsu Key Laboratory of Advanced Metallic Materials, School of Materials Science and
Engineering, Southeast University, Nanjing, 211189, PR China
d Department of Material Science and Engineering, KTHꢀRoyal Institute of Technology, SEꢀ
10044 Stockholm, Sweden
e Department of Physics and Astronomy, Uppsala University, Box 516, SEꢀ75120 Uppsala,
Sweden
Author contribution
† These authors contributed equally
*Corresponding authors. Tel.: +862585092237. Eꢀmail address: (M.W.)
101010078@seu.edu.cn, (N.H.) nyhe@seu.edu.cn
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Abstract: The formation of three mixed binary Charge transfer (CT) cocrystals with
tunable photoluminescence behavior featuring both CT interaction and directional hydrogen
bonding is presented. Our strategy consists of the CT induced coꢀcrystallization of three
polycyclic (naphthalene, anthracene and pyrene) carrying αꢀcyanostilbene (CS) derivatives
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namely,
3ꢀ(naphthaleneꢀ2ꢀyl)ꢀ2ꢀ(pꢀtolyl)
acrylonitrile
(NPA)
3ꢀ(anthraceneꢀ9ꢀyl)ꢀ2ꢀ
phenylacrylonitrile (APA), and 2ꢀ(4ꢀmethoxyphenyl)ꢀ3ꢀ(pyreneꢀ1ꢀyl) acrylonitrile (MPA) as
donors (D) with 1,2,4,5ꢀtetracyanobenzene (TCNB) as an acceptor (A). The asꢀprepared
cocrystals were probed in detail by various analytical techniques namely, Xꢀray diffraction data,
vibrational spectroscopy, diffuse reflectance absorption spectroscopy, fluorescence properties
and fluorescence quantum yields and lifetimes, affirming the formation of CT complexes.
Complex IA features mixed stack arrangement (DꢀAꢀDꢀAꢀD) while IIA and IIIA revealed
(DADꢀꢀꢀDAD) stack arrangement. The CT products showed distinct tunable emission colors
and photoluminescence characteristics which is closely associated with the CT interactions
between the donor and acceptor moiety, and ionization potential or the πꢀelectron rich character
of the polycyclic moiety of the donor molecule. This research demonstrates the development of
new hybrid CT functional materials with enhanced optical properties such as absorption,
fluorescence emissions, and lifetimes compared to the pristine donors, which is important for
the exploration of new solidꢀstate luminescent materials.
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Introduction
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Engineered solidꢀstate organic luminescent materials have shown booming development in the
past decades by virtue of their emerging applications in laser1, pharmaceuticals2, sensors3,
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optoelectronics2,
and optical waveguides6 etc. In this direction, tuning the optical
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characteristics of the organic chromophore in the solid state is interesting and challenging
owing to their practical applications in various research domains 7ꢀ12. On the other hand, to
obtain such promising materials with desired characteristics is not without a challenge as these
compounds are strong emissive in the molecularly dispersive state but become weak or nonꢀ
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emissive in condensed phase owing to molecular aggregation . Thus, particular consideration
has been devoted to understand and modulate various intermolecular interactions towards
designing potential smart organic solid chromophores with high emission in the aggregated
states. To this end, several approaches have been explored by supramolecular chemists to
sophisticatedly control and modulate various nonꢀcovalent interactions in order to realize a
supramolecular assembly with promising functionality.
Charge transfer (CT) induced selfꢀassembly represents a promising approach in order to
improve the optical properties and has been considered widely as an effective way to realize the
donorꢀacceptor (DꢀA) systems through nonꢀcovalent bonds by orientation processing where the
molecules are aligned in the solid state in face to face fashion to form either mixed stacking
assemblies or segregated. The versatility in the choice of D and A from the diverse library of the
organic compounds, make this approach quite fascinating due to their different orientation and
stacking modes in the resulting solid state selfꢀassembly which in turn may beneficial for tuning
the luminescence efficiency of the organic materials.
Cyanostilbene (CS) type chromophores are promising candidates for the development of new
organic functional materials because of their prominent optoelectronic properties 14, 15. Recently,
these compounds have been employed to fabricate various fascinating CT supramolecular
assemblies with tunable emission compared to the individual D/A compounds 16ꢀ21. Due to the
ease of functionalization of αꢀcyanostilbene at terminal position and the hydrogen bond
interaction ability of cyano group, it offers a facile way to synthesize two components
molecular aggregates 3, 16, 20, 22. Herein, we have designed polycyclic (naphthalene, anthracene,
and pyrene) functionalized αꢀCS derivatives viz 3ꢀ(naphthaleneꢀ2ꢀyl)ꢀ2ꢀ(pꢀtolyl) acrylonitrile (NPA)
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3ꢀ(anthraceneꢀ9ꢀyl)ꢀ2ꢀphenylacrylonitrile (APA), and 2ꢀ(4ꢀmethoxyphenyl)ꢀ3ꢀ(pyreneꢀ1ꢀyl) acrylonitrile
(MPA) as donors with 1,2,4,5ꢀtetracyanobenzene (TCNB) as an acceptor (scheme 2) to fabricate
luminescent mixed CT complexes towards tuning the emission characteristics based on the
structureꢀluminescence relationships. The CT interactions in these cocrystals have been
investigated extensively using spectroscopic measurements which demonstrated that the CT
interactions can be modulated by CT induced cocrystallization strategy leading to the tunable
photophysical properties. This study offers a facile way to develop new solid state multiꢀcolor
CT fluorescent materials.
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EXPERIMENTAL SECTION
1,2,4,5ꢀTetracyanobenzene (CAS: 712ꢀ74ꢀ3), 4ꢀmethylphenylacetonitrile, phenyl acetonitrile 4ꢀ
Methoxyphenylacetonitrile,
2ꢀNaphthaldehyde,
9ꢀAnthracenecarboxaldehyde,
1ꢀ
Pyrenecarbaldehyde, Sodium methoxide and solvents were purchased from commercial sources
and used directly without further purification.
Synthesis of the donors compounds
The three donor compounds in the present work were synthesized from the previously reported
method23. As shown in Scheme 1, to a 250 ml flask a mixture of 4ꢀmethylphenylacetonitrile
(1.05 g, 9 mmol)/4ꢀphenylacetonitrile (1.27 g, 9 mmol)/4ꢀMethoxyphenylacetonitrile (1.18 g, 9
mmol) and 2ꢀNaphthaldehyde (1.40 g, 9 mmol)/ 9ꢀAnthracenecarboxaldehyde (1.85 g, 9
mmol)/1ꢀPyrenecarbaldehyde (2.07 g, 9 mmol) and Sodium methoxide (0.162 g, 3 mmol) in
ethanol (20 mL) was stirred at room temperature for 4 h by monitoring the reaction through
TLC. After the reaction, the resulting solids were filtered and dried followed by recrystallization
from ethyl acetate to yield NPA, APA, and MPA in 76 %, 80 % and 72 % respectively.
(1H NMR NAP; (CDCl3 Figure S1 of the Supporting Information. δ (ppm) 2.43 (s, 3H), 7.46 (d,
2H), 7.52 (d, 2H), 7.54 (d, 2H), 7.69 (s, 1H), 7.73 (d, 1H), 7.89 (m, 2H), 8.08 (s, 1H), 8.29 (d,
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1H). C NMR NAP; (CDCl3 Figure S2 of the Supporting Information. δ (ppm) 21.23, 111.67,
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118.26, 125.31, 125.90, 126.77, 127.54, 127.76, 128.68, 128.75, 129.78, 130.21, 131.45,
131.88, 133.17, 134.10, 139.45, 141.20
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1H NMR APA; (CDCl3 Figure S3 of the Supporting Information δ (ppm) 7.55 (m, 3H), 7.58 (m,
3H), 7.59 (m, 1H), 7.93 (m, 2H), 8.09 (m, 4H), 8.48 (s, 1H) 8.59 (s, 1H). (13C NMR APA;
(CDCl3 Figure S4 of the Supporting Information. δ (ppm) 116.51, 121.31, 125.03, 125.55,
126.16, 126.68, 127.88, 128.98, 129.13, 129.32, 129.47, 129.84, 131.31, 133.31, 140.18.
1H NMR MPA; (CDCl3 Figure S5 of the Supporting Information) δ (ppm) 3.92 (s, 3H), 6.70
(dd, 2H), 7.02 (dd, 2H), 7.77 (t, 1H), 7.79 (m, 2H) 8.04 (m, 3H), 8.16 (m, 2H) 8.39 (s, 1H), 8.54
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(d, 1H), C NMR MPA; (CDCl3 Figure S6 of the Supporting Information. δ (ppm) 55.51,
114.55, 118.33, 122.67, 124.61 124.75 124.97, 125.06 125.89, 126.12, 126.30, 126.88, 127.13,
127.45, 127.51, 128.29, 128.55, 128.58, 129.71, 130.74, 131.31, 132.59, 138.19, 160.72.
Preparation of the CT CoꢀCrystal
Synthesis of IA. An equimolar quantity of the NPA (0.1 mmol, 26.9 mg) and TCNB (0.1
mmol, 17.8 mg) were dissolved in 15 ml acetone/dichloromethane (10:5) mixed solvent in a
flask. Rodꢀshaped light green crystals suitable for singleꢀcrystal Xꢀray diffraction were
harvested after one week of evaporation at room temperature (80% yield). Elemental Analysis
(%) calculatedꢀ80.52, 3.83, 15.65, found: C 80.22, H 3.55, N 15.45.
Synthesis of IIA. An equimolar quantity of the APA (0.1 mmol, 30.5 mg) and TCNB (0.1
mmol, 17.8 mg) were dissolved in 15 ml acetone/dichloromethane (10:5) mixed solvent in a
flask. Rodꢀshaped orangeꢀred crystals suitable for singleꢀcrystal Xꢀray diffraction were
harvested after oneꢀweek evaporation at room temperature (78 % yield). Elemental Analysis
(%) calculated: 81.97, 3.54, 14.48 found: C 81.75, H 3.42, N 14.32.
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Synthesis of IIIA. An equimolar quantity of the MPA (0.1 mmol, 35.9 mg) and TCNB (0.1
mmol, 17.8 mg) were dissolved in 15 ml acetone/dichloromethane (10:5) mixed solvent in a
flask at room temperature. Rodꢀshaped red crystals suitable for singleꢀcrystal Xꢀray diffraction
were harvested after one week of evaporation at room temperature (70% yield). Elemental
Analysis (%): calculated: 80.43, 3.56, 13.03, found: C 80.25, H 3.41, N 12.96.
Measurement Studies
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The PXRD patterns for the crystals were recorded using an 18 KW advance Xꢀray
diffractometer with Cu Kα radiation (λ = 1.54056 Å). Single Xꢀray diffraction data for crystals
IA, IIA and IIIA were collected on Nonius CAD4 diffractometer with Mo Kα radiation (λ=
0.71073 Å). The structures were solved by direct methods using the SHELXLꢀ2014/7 program
and refined anisotropically using fullꢀmatrix leastꢀsquares procedure24. All nonꢀhydrogen atoms
were refined anisotropically and were inserted at their calculated positions and fixed at their
positions.
Spectroscopic Measurements.
1H NMR and 13C spectra were recorded at 303 K on a Bruker Avance 500 MHz NMR
spectrometer using CDCl3 as a solvent and TMS as an internal standard. Infrared spectra were
recorded on a Bruker Tensor 27 FTꢀIR spectrometer with KBr pellets. UVꢀVis absorption spectra
were collected on a Shimadzu UVꢀ3600 spectrometer. Fluorescence spectra were obtained on a
Horiba FluoroMax 4 spectrofluorometer.
Fluorescence microscopy images. Fluorescence microscopy images were collected on the
Olympus BX51 imaging system excited at 365 nm. Solid fluorescent quantum yields were
performed using Quantaꢀφ accessory with excitation wavelength at 320 nm. Fluorescence
lifetime measurements for the crystals were undertaken by the timeꢀcorrelated singleꢀphoton
counting technique (TCSPC) using a TemPro Fluorescence Lifetime System (Horiba Jobin
Yvon) equipped with a NanoLed excitation source of 340 nm.
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Computational Methods
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All calculations were obtained via the density functional theory (DFT) by using the Vienna Ab
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Initio Simulation Package (VASP)
with an exchangeꢀcorrelation functional parameterized
by the generalized gradient approximation (GGA) of the Perdew–Burke–Ernzerhof (PBE)
functional27ꢀ29. An energy cutoff of 450 eV in the framework of planeꢀwave basis set was
employed, and its convergence criterial was set to total energy converged to 1 × 10−5 eV. The
optimization was terminated until the and the residual force on each atom was less than 0.01
eV/Å. During the totalꢀenergy calculations, a Monkhorst–Pack30 kꢀpoint grid of 3 × 3 × 1 was
adopted for cocrystal IA and 2 × 2 × 1 was used for cocrystal IIA and IIIA.
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Results and Discussion
Spectral characterization
As expected, one signal can be observed at 2.43 ppm in the NPA compound, which is attributed
to the methyl protons. The stilbene proton is embedded in the aromatic region at 7.69 ppm due
to attachment with the aromatic system. The signals at 7.4ꢀ8.30 are corresponding to the
fourteen aromatic protons. In APA, all the protons are aromatic and therefore appeared in the
aromatic region except stilbene proton, which is a nonꢀaromatic and appeared in the aromatic
region at 8.48 ppm due to high deshieding effect owing to the ethylenic bond and attachment
with the arometic piꢀconjugated system. In the MPA, a signal at 3.92 ppm is assigned to the
methoxy protons while the stilbene proton appeared in the aromatic region at 8.39 ppm owing to
the same reason discussed earlier while the signals at 6.7ꢀ8.5 ppm attributed to the aromatic
protons of benzene and pyrene ring respectively.
Crystal Structures description
Singleꢀcrystal Xꢀray diffraction study was exploited for the three crystalline materials to
identify the various intermolecular interaction modes in the solid state. Structural analysis of the
Coꢀcrystal IA reveals 1:1 stoichiometric ratio of donor and acceptor molecule while 2:1 for the
pair IIA and IIIA in an asymmetric unit. The detailed crystallographic information and various
interactions modes of these CT materials are depicted in Table. 1, 2, and 3 respectively.
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Cocrystal IA.
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The Cocrystal IA crystalized in P21 space group with one molecule each of APA and TCNB in
the unit cell having a mixed stack arrangement of (DꢀAꢀDꢀAꢀD). The TCNB molecules are
stabilized between the benzene and naphthalene rings of the two paralleled stack APA
molecules one above and the other below the TCNB core plane to form a layer structure through
CꢀH···N and CT π···π interactions (Table 2 and 3) (see figure 1). The layered structure is
maintained by H26A···N2 along c axis extending further the network to form a 2D structure.
Cocrystal IIA
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The Cocrystal IIA belongs to Pī space group with one molecule of NPA and halfꢀmolecule of
the TCNB constitute the asymmetric unit. The NPA and TCNB molecules are arranged in an
alternate fashion to form a columnar mixed stack packing (DADꢀꢀꢀDAD) directed by the Cꢀ
H···N and CT π···π interactions (Table 2 and 3). Furthermore, the columnar structure is further
extended along c axis using H24A···π, π ···π, and H···N interactions, leading to the formation
of 2D assembly (figure 2).
Cocrystal IIIA
Cocrystal IIIA is assembled in Pī space group with one molecule of MPA and halfꢀmolecule of
the TCNB in an asymmetric unit. The individual DꢀA molecular pairs are associated with H···N
and CT π···π interactions (Table 2 and 3) to form a columnar framework similar to the cocrystal
IIA. The TCNB molecules are perfectly sandwiched between the pyrene units of the MPA
molecules with a centroid distance of 3.489 and extend the network further via H7A··· π and
H22A··· π to form 2D superstructure.
Powder Xꢀray Diffraction Analysis (PXRD)
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Powder Xꢀray Diffraction analysis (PXRD) was performed in an effort to evidence the
formation of CT cocrystals. New patterns can be noticed in the XRD spectrum of the asꢀ
prepared CT products compared to the donors compounds, suggesting that new selfꢀassemblies
have been generated exclusively as a result of the charge transfer interactions mode (figure S7
of supporting information). Interestingly, the position of diffraction peaks of the CT complexes
were well matched with the simulated pattern obtained from the Single XRD, indicated that the
bulk CT complexes possess crystallinity and have the same framework (Figure 4). However,
few discrepancies between the peaks intensity values of experimental PXRD pattern compared
to the simulated might be caused by preferred orientations of the experimental powder samples
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31, 32
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Spectroscopic Investigation
FTꢀIR Spectroscopy
Vibration spectroscopy is an efficient tool to affirm the existence of nonꢀcovalent interactions
and is therefore used extensively to evaluate the type of intermolecular interactions in the DꢀA
CT systems. In the FTIR spectra of IA, IIA, and IIIA no variations in the main vibration bands
of the C≡N stretching was noted compared to the TCNB which is matched with the earlier
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reported work . Unlike the C≡N band, more remarkable variations (Figure 5) were observed
in the characteristics (CꢀH str) and (C≡C str) bands of the cocrystals (CꢀH strꢀ IA: 3044 cmꢀ1
and 3111 cmꢀ1, IIA: 3038 cmꢀ1 and 3107 cmꢀ1, IIIA: 3038 cmꢀ1 and 3102 cmꢀ1; C≡C strꢀ IA:
1489 cmꢀ1 – IIA: 1488 cmꢀ1 and IIIA: 1489 cmꢀ1) with respect to the Isolated TCNB (CꢀH strꢀ
3049 cmꢀ1 and 3113 cmꢀ1; C≡C str 1485 cmꢀ1), illustrating the increasing electron cloud density
of benzene ring upon the formation of CT selfꢀassembly 34, 35. This result implies that different
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CTꢀπꢀπ interactions and hydrogen bonding influences the vibration properties of DꢀA selfꢀ
assembly and prompt us to further investigate the CT state.
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Solid State UV Spectra
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Solidꢀstate UV is the most efficient analytical technique to probe the CT state of the solid
materials 25ꢀ27. As evident from figure 6, in all the three CT systems emergence of new redꢀ
shifted absorption bands can be detected with respect to the pristine donors pointing to the
formation of strong CT interaction in the three complexes 38. For IA an absorption peak
centered at 436 nm, while broad absorption peaks range from 433 nm to 545 nm for IIA and
330 nm to 583 nm for IIIA respectively, can be observed which is in line with what would be
expected for a larger πꢀsystem. Moreover, the three CT materials exhibit variant luminescence
color such as light green (IA), orangeꢀred (IIA) and dark red (IIIA) under UV light that can be
facially detected to naked eye reflecting the prominent CT characteristics (Figure 7).
Luminescent behaviors of the Cocrystals
The successful combination of donors and acceptor resulted in the CT selfꢀassembly making the
asꢀobtained complexes luminescent solids with variable emission behaviors depending upon the
attached polycyclic πꢀsegment in the donors. Compared with the pristine donors the CT
molecular aggregates exhibited distinct red shifts (IA: 508 nm, IIA: 619 nm, IIIA: 649 nm) in
the emission spectra (Figure 8), implying the generation of characteristic CT state in the
resulting complexes 28, 29. It is interesting to note that the linear increase in the observed
emission properties of these cocrystals is associated with the IP of the polycyclic πꢀmoiety of
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the donors (Naphthaleneꢀ8.14 eV, Anthraceneꢀ7.44 eV, Pyreneꢀ7.43 eV). The donors with a
larger polycyclic πꢀmoiety (MPA) exhibited a small value of IP and tend to have emission at
higher wavelength against the one having a large value of IP (APA).
We noticed that the photoluminescence properties increases linearly with the increase in the
number of benzene rings in the donor molecule, regardless of the 1:1 (IA) or 1:2 (IIA and IIIA)
stoichiometry. The large πꢀmoiety system is a significant factor in the current organic chargeꢀ
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transfer systems bringing the LUMO of the acceptor much closer to the HUMO of donors
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(naphthalene˂anthracene˂pyrene), which resulted in the enhancement of photophysical
properties. However, IIA and IIIA also exhibited CH···π interactions in the adjacent stacks
which are not shown by the IA resulting in a more compact structure thereby also contributing
to the improvement of the optical characteristics.
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To shed further light on the photophysical characteristics of the CT materials, we focused on the
emission quantum yields (ΦF) and fluorescence lifetime (τF) measurements and the results are
illustrated in Table 4. It is interesting to note that the fluorescence efficiency of the CT
cocrystals (τ: 422 ns, for NPA, 6.3 ns for APA, 2.04 ns for MPA and 7.1 ns IA, 12.2 ns IIA, 12.1 ns
for IIIA respectively) were increased compared to the donors reflecting that the photophysical
properties can also be tuned successfully by such CT induced assembly. Furthermore, the asꢀ
prepared materials showed higher fluorescence lifetime (decays curves figure S8 of supporting
information) than the pristine donors revealing the formation of a CT state generated by the
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TCNB which is more stable than the S0ꢀS1.
Theoretical Results
As depicted in Figure 9, we can find that all three cocrystals are semiconductors with bandgaps
of about 1.01, 0.56 eV, and 0.52 eV for type IA, IIIA, and IIIA, respectively. Among these, for
IA and IIA, the contribution to valence band maximum (VBM) mainly rises from the carbon
atoms (C), while for the conduction band minimum (CBM) it can be contributed by the carbon
and nitrogen (N) atoms. On the contrary, for cocrystal IIIA having the least band gap, C and
oxygen (O) atoms are the major sources for the VBM, and only C atoms mainly contribute to
the CBM. While the IA cocrystal possesses a wider bandgap of about 1eV, the other two both
have a 0.5 eV bandgap but with different states of band edges. It is, therefore, all studied those
cocrystals are grounded to narrow bandgap semiconductors absorbing visible light, and the
distinct band gaps with varying band edge states determine the unique optical properties for
each cocrystal. In addition, it can also be noticed that below the Fermi level, there are several
quasiꢀdiscrete states in all cocrystals, which is obviously originating from the low symmetric
and molecularꢀlike structures. Going to the deeper energy scale, one can scarcely identify strong
hybridization states between C and N/O illustrating the weak covalence bonding.
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The current study demonstrates the excellent tunability of the optical properties in a series of
three new binary CT DꢀA cocrystals by virtue of strong CT interactions. Structural analysis
indicated strong CT π···π and hydrogen bonds driven mixed stack arrangement (Complex IA: Dꢀ
AꢀDꢀAꢀD, IIA, and IIIA: DADꢀꢀꢀDAD) in these twoꢀcomponent molecular aggregates. The
tunable emission and enhancement of luminescent efficiency are associated with the Ionization
potential of the polycyclic moiety of the donors and the CT interactions in these complexes. It is
envisaged that such CT induced solidꢀstate selfꢀassembly of two components DꢀA building
blocks can be extended to other systems allowing to fabricate functional materials with tunable
photoꢀphysical properties that can have potential optoelectronic applications.
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ꢀ ASSOCIATED CONTENT
Supporting Information
1H NMR for the donors compounds and Xꢀray crystallographic information files (CIF) for IA,
IIA, and IIIA; This information is available free of charge via the Internet at http://pubs.acs.org.
ꢀ AUTHOR INFORMATION
Corresponding Authors
*Eꢀmail: wangmlchem@seu.edu.cn. Tel: +862585092237.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENT
The funding for this project is supported by the Priority Academic Program Development of
Jiangsu Higher Education Institutions (1107047002).
References
(1)
Schmidtke, J.; Stille W.; Finkelmann H.; Kim, S.T. Laser Emission in a Dye Doped
Cholesteric Polymer Network, Adv Mater. 2002, 14, 746ꢀ749.
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1
2
3
4
(2)
Lei, Y. L.; Liao, L. S.; Lee, S. T. Selective growth of dualꢀcolorꢀemitting heterogeneous
5
6
7
microdumbbells composed of organic chargeꢀtransfer complexes. J. Am. Chem. Soc. 2013, 135,
3744ꢀ7.
8
9
(3)
Dongpeng, Y.; Amit, D.; O., L. G.; Tomislav, F.; M., D. G.; William, J.; Jun, L.; Min,
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
W.; G., E. D.; Xue, D. A, Cocrystal Strategy to Tune the Luminescent Properties of Stilbene
Type Organic Solid State Materials. Angew. Chem., Int. Ed. 2011, 50, 12483ꢀ12486.
(4)
Prospective Organic Electronics Materials, J. Phys. Soc. Jpn. 2006, 75, 051016.
(5) Goetz, K. P.; Vermeulen, D.; Payne, M. E.; Kloc, C.; McNeil, L. E.; Jurchescu, O. D.
Horiuchi, S.; Hasegawa, T.; Tokura, Y. Molecular Donor–Acceptor Compounds as
Chargeꢀtransfer complexes: new perspectives on an old class of compounds, J. Mater. Chem. C.
2014, 2, 3065ꢀ3076.
(6)
Zhu, W.; Zhu, L.; Zou, Y.; Wu, Y.; Zhen, Y.; Dong, H.; Fu, H.; Wei, Z.; Shi, Q.; Hu, W.
Deepening Insights of Charge Transfer and Photophysics in a Novel DonorꢀAcceptor Cocrystal
for Waveguide Couplers and Photonic Logic Computation, Adv. Mater. 2016, 28, 5954ꢀ62.
(7)
Qin, Y.; Zhang, J.; Zheng, X.; Geng, H.; Zhao, G.; Xu, W.; Hu, W.; Shuai, Z.; Zhu, D.
Chargeꢀtransfer complex crystal based on extendedꢀpiꢀconjugated acceptor and sulfurꢀbridged
annulene: chargeꢀtransfer interaction and remarkable high ambipolar transport characteristics,
Adv Mater. 2014, 26, 4093ꢀ9.
(8)
Tsutsumi, J. y.; Yamada, T.; Matsui, H.; Haas, S.; Hasegawa, T. ChargeꢀTransfer
Exciton Dissociation and Direct Photocarrier Generation in Molecular DonorꢀAcceptor
Compounds, Phys. Rev. Lett. 2010, 105, 226601.
(9)
Horiuchi, S.; Ishii, F.; Kumai, R.; Okimoto, Y.; Tachibana, H.; Nagaosa, N.; Tokura, Y.
Ferroelectricity near room temperature in coꢀcrystals of nonpolar organic molecules, Nat Mater.
2005, 4, 163ꢀ6.
(10) Ren, Y.; Hailey, A. K.; Hiszpanski, A. M.; Loo, Y.ꢀL. IsoindigoꢀContaining Molecular
Semiconductors: Effect of Backbone Extension on Molecular Organization and Organic Solar
Cell Performance, Chem. Mater. 2014, 26, 6570ꢀ6577.
(11) Morimoto, M.; Irie, M. A Diarylethene Cocrystal that Converts Light into Mechanical
Work, J. Am. Chem. Soc. 2010, 132, 14172ꢀ14178.
(12) Nguyen, H. L.; Horton, P. N.; Hursthouse, M. B.; Legon, A. C.; Bruce, D. W. Halogen
bonding: a new interaction for liquid crystal formation, J. Am. Chem. Soc. 2004, 126, 16ꢀ7.
ACS Paragon Plus Environment

Crystal Growth & Design
Page 14 of 26
1
2
3
4
5
6
(13) Shi, J.; Aguilar Suarez, L. E.; Yoon, S.ꢀJ.; Varghese, S.; Serpa, C.; Park, S. Y.; Lüer, L.;
RocaꢀSanjuán, D.; MiliánꢀMedina, B.; Gierschner, J. J. J. Phys. Chem. C. 2017, 121, 23166ꢀ
23183.
7
8
9
(14) Martínez Abadía, M.; Giménez, R.; Ros María, B. Self Assembled α Cyanostilbenes
for Advanced Functional Materials, Adv Mater. 2017, 30, 1704161.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(15) Zhang, Y.; Huang, J.; Kong, L.; Tian, Y.; Yang, J. Two novel AIEEꢀactive imidazole/
[small alpha]ꢀcyanostilbene derivatives: photophysical properties, reversible fluorescence
switching, and detection of explosives, CrystEngComm. 2018, 20, 1237ꢀ1244.
(16) Kyu, P. S.; Hong, K. J.; Tatsuhiko, O.; Ryo, Y.; F., J. A. O.; Ryeol, W. D.; Illhun, C.;
Sangyoon, O.; Hwa, H. S.; Eon, K. J.; H., K. J.; Yoann, O.; Roland, F.; Roland, R.; Johannes,
G.; Hirokazu, T.; Young, P. S. Highly Luminescent 2D Type Slab Crystals Based on a
Molecular Charge Transfer Complex as Promising Organic Light Emitting Transistor
Materials, Adv Mater. 2017, 29, 1701346.
(17) Park, S. K.; Varghese, S.; Kim, J. H.; Yoon, S.ꢀJ.; Kwon, O. K.; An, B.ꢀK.; Gierschner,
J.; Park, S. Y. TailorꢀMade Highly Luminescent and Ambipolar Transporting Organic Mixed
Stacked ChargeꢀTransfer Crystals: An Isometric Donor–Acceptor Approach, J. Am. Chem. Soc.
2013, 135, 4757ꢀ4764.
(18) Hyeong Ju, K.; Ryeol, W. D.; Johannes, G.; Han, L. C.; Young, P. S. High Contrast
Red–Green–Blue Tricolor Fluorescence Switching in Bicomponent Molecular Film, Angew.
Chem., Int. Ed. 2015, 54, 4330ꢀ4333.
(19) Wykes, M.; Park, S. K.; Bhattacharyya, S.; Varghese, S.; Kwon, J. E.; Whang, D. R.;
Cho, I.; Wannemacher, R.; Lüer, L.; Park, S. Y.; Gierschner, J. Excited State Features and
Dynamics in a DistyrylbenzeneꢀBased Mixed Stack Donor–Acceptor Cocrystal with
Luminescent Charge Transfer Characteristics, J. Phys. Chem. Lett. 2015, 6, 3682ꢀ3687.
(20) Fan, G.; Yan, D. Positional isomers of cyanostilbene: twoꢀcomponent molecular
assembly and multipleꢀstimuli responsive luminescence, Sci. Rep. 2014, 4, 4933.
(21) Kyu, P. S.; Illhun, C.; Johannes, G.; Hong, K. J.; H., K. J.; Eon, K. J.; Kyu, K. O.; Ryeol,
W. D.; Jung Hwa, P.; Byeong Kwan, A.; Young, P. S. Stimuli Responsive Reversible
Fluorescence Switching in a Crystalline Donor–Acceptor Mixture Film: Mixed Stack Charge
Transfer Emission versus Segregated Stack Monomer Emission, Angew. Chem., Int. Ed. 2016,
55, 203ꢀ207.
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1
2
3
4
5
6
7
8
9
(22) Zhu, L.; Zhao, Y. Cyanostilbeneꢀbased intelligent organic optoelectronic materials, J
Mater Chem C. 2013, 1, 1059ꢀ1065.
(23) An, P.; Xu, N.ꢀS.; Zhang, H.ꢀL.; Cao, X.ꢀP.; Shi, Z.ꢀF.; Wen, W. A New Class of Colorꢀ
Tunable Solid Emitters, Chem. Asian J. 2015, 10, 1959ꢀ1966.
10
11
12
13
14
15
16
17
18
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24
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50
51
52
53
54
55
56
57
58
59
60
(24) Sheldrick, G. Crystal structure refinement with SHELXL, Acta Crystallogr., Sect. C.
2015, 71, 3ꢀ8.
(25) Kresse, G.; Furthmüller, J. Efficiency of abꢀinitio total energy calculations for metals
and semiconductors using a planeꢀwave basis set Comput. Mater. Sci. 1996, 6, 15ꢀ50.
(26) Kresse, G.; Furthmüller, J. Efficient iterative schemes for ab initio totalꢀenergy
calculations using a planeꢀwave basis set, Phys Rev B. 1996, 54, 11169ꢀ11186.
(27) Perdew, J. P.; Burke, K.; Ernzerhof, M. Generalized Gradient Approximation Made
Simple, Phys Rev Lett. 1996, 77, 3865ꢀ3868.
(28) Perdew, J. P.; Burke, K.; Ernzerhof, M. Generalized Gradient Approximation Made
Simple Phys Rev Lett. 1997, 78, 1396ꢀ1396.
(29) Kresse, G.; Joubert, D. From ultrasoft pseudopotentials to the projector augmentedꢀwave
method, Phys Rev B. 1999, 59, 1758ꢀ1775.
(30) Monkhorst, H. J.; Pack, J. D. Special points for Brillouinꢀzone integrations, Phys Rev B.
1976, 13, 5188ꢀ5192.
(31) Dong, B.; Wang, M.; Xu, C.; Feng, Q.; Wang, Y. Tuning SolidꢀState Fluorescence of a
Twisted πꢀConjugated Molecule by Regulating the Arrangement of Anthracene Fluorophores,
Cryst. Growth Des. 2012, 12, 5986ꢀ5993.
(32) Sun, H.; Wang, M.; Khan, A.; Shan, Y.; Zhao, K.; Usman, R.; Xu, C. ChemistrySelect.
2017, 2, 6323ꢀ6330.
(33) Arrais, A.; Boccaleri, E.; Croce, G.; Milanesio, M.; Orlando, R.; Diana, E. Coꢀcrystals
with Delayed Fluorescence Assembled by 1,4ꢀDiiodotetrafluorobenzene and Polycyclic
Aromatic Compounds via Halogen Bonds, CrystEngComm. 2003, 5, 388ꢀ394.
(34) Yu, W.; Weigang, Z.; Wenna, D.; Xinfeng, L.; Xiaotao, Z.; Huanli, D.; Wenping, H.
Cocrystals Strategy towards Materials for Near Infrared Photothermal Conversion and
Imaging, Angew Chem Int Ed 2018, 57, 3963ꢀ3967.
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Page 16 of 26
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4
5
6
7
8
9
(35) Zhu, W.; Zhu, L.; Zou, Y.; Wu, Y.; Zhen, Y.; Dong, H.; Fu, H.; Wei, Z.; Shi, Q.; Hu, W.
Deepening Insights of Charge Transfer and Photophysics in a Novel Donor–Acceptor Cocrystal
for Waveguide Couplers and Photonic Logic Computation,Adv. Mater. 2016, 28, 5954ꢀ5962.
(36) Silvia, B.; Augusto, B. J.; Paola, G.; Maxime, G.; Lorenzo, F.; Miriam, M. Peptide
Driven Charge Transfer Organogels Built from Synergetic Hydrogen Bonding and Pyrene–
Naphthalenediimide Donor–Acceptor Interactions, Chem. Asian J. 2018, 24, 2920ꢀ2928.
(37) Blackburn, A. K.; Sue, A. C. H.; Shveyd, A. K.; Cao, D.; Tayi, A.; Narayanan, A.;
Rolczynski, B. S.; Szarko, J. M.; Bozdemir, O. A.; Wakabayashi, R.; Lehrman, J. A.; Kahr, B.;
Chen, L. X.; Nassar, M. S.; Stupp, S. I.; Stoddart, J. F. LockꢀArm Supramolecular Ordering: A
Molecular Construction Set for Cocrystallizing Organic Charge Transfer Complexes, J. Am.
Chem. Soc. 2014, 136, 17224ꢀ17235.
10
11
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52
53
54
55
56
57
58
59
60
(38) Zhu, W.; Zheng, R.; Fu, X.; Fu, H.; Shi, Q.; Zhen, Y.; Dong, H.; Hu, W. Revealing the
chargeꢀtransfer interactions in selfꢀassembled organic cocrystals: twoꢀdimensional photonic
applications, Angew. Chem., Int. Ed. 2015, 54, 6785ꢀ9.
(39) Khan, A.; Wang, M.; Usman, R.; Sun, H.; Du, M.; Xu, C. Molecular Marriage via
Charge Transfer Interaction in Organic Charge Transfer CoꢀCrystals toward SolidꢀState
Fluorescence Modulation, Cryst. Growth Des. 2017, 17, 1251ꢀ1257.
(40) Sun, H.; Peng, J.; Zhao, K.; Usman, R.; Khan, A.; Wang, M. Efficient Luminescent
Microtubes of ChargeꢀTransfer Organic Cocrystals Involving 1,2,4,5ꢀTetracyanobenzene,
Carbazole Derivatives, and Pyrene Derivatives, Cryst. Growth Des. 2017, 17, 6684ꢀ6691.
(41) Garai, A.; Mukherjee, S.; Ray, S. K.; Biradha, K. Tuning Emission Properties via
Aromatic Guest Inclusion in Organic Salts Composed of 4,4′ꢀDinitroꢀ2,2′,6,6′ꢀ
tetracarboxybiphenyl and Acridine, Cryst. Growth Des. 2018, 18, 581ꢀ 586.
(42) Hu, P.; Du, K.; Wei, F.; Jiang, H.; Kloc, C. Crystal Growth, HOMO–LUMO
Engineering, and Charge Transfer Degree in PeryleneꢀFxTCNQ (x = 1, 2, 4) Organic Charge
Transfer Binary Compounds, Cryst. Growth Des. 2016, 16, 3019ꢀ3027.
(43) Yukihiro, Y.; Yasuhiro, S.; Takeshi, Y.; Goro, M.; Sadamu, T.; Yoshiaki, N.; Takaaki,
H.; Hiroshi, K.; Hideki, Y.; Gunzi, S. Molecular Rotors of Coronene in ChargeꢀTransfer Solids,
Chem. Eur. J. 2013, 19, 12313ꢀ12324.
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Scheme 1. Structures of the acceptor and donor molecules
Figure 1. Illustration for the Coꢀcrystal structure IA. Orange and Cyan color dash lines
represent CT π···π and hydrogen bonds respectively.
Figure 2. Illustration for the column structure of crystal IIA. Plum color dash lines
represent CT π···π and yellow demonstrate hydrogen bonding.
Figure 3. Illustration for the crystal structure IIIA. Pink and cyan color dash lines present
CT CT π···π and hydrogen bonds respectively.
Figure 4. PXRD pattern of CT coꢀcrystals simulated (black) and experimental (red).
Figure 5. FTꢀIR spectra of CT crystals b) CꢀH str and c) C≡C str
Figure 6. Solid state absorption spectra of the CT complexes
Figure 7. Fluorescence microscopy images of crystals IA ꢀIIIA (λex=365nm). The scale bar
is 200 ꢁm
Figure 8. Fluorescence spectra of CT crystals (λex=385nm).
Figure 9. The calculated total density of states (TDOS) and atom projected density of
states (PDOS) of (a) cocrystal IA, (b) cocrystal IIA, (c) cocrystal IIIA. The Fermi level
is set to zero and indicated by green vertical dash line.
Table 1. Details of Crystallographic Data for the CT cocrystals
Table 2. Intermolecular Hydrogen Bonds Parameters in CT crystals
Table 3. Faceꢀtoꢀface πꢀstacking interactions between acceptor and polycyclic moieties in
the respective donor molecules
Table 4. Solid state photophysical property data of donors and cocrystals
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Scheme. 1
Scheme. 2
Figure 1.
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Figure 2.
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Figure. 9
Table. 1
Crystal
IA
IIA
IIIA
Formula
Temperature/K
Crystal size/mm3
Morphology
D/A Stoichiometry
Crystal system
Space group
a/ Å
C40H19lN9
293
C56H32N5
293
C62H36N6O2
293
0.20×0.20×0.10 0.30×0.20×0.10
0.30×0.20×0.10
rod
rod
rod
1:1
2:1
2:1
Monoclinic
P21
Triclinic
Pī
Triclinic
Pī
7.3430(15)
7.5600(15)
29.249(6)
90.00
9.2680(19)
9.789(2)
12.891(3)
92.46(3)
104.78(3)
114.41(3)
1015.0(4)
2
9.844(2)
10.404(2)
11.351(2)
95.21(3)
96.75(3)
95.34(3)
1143.4(4)
2
b/ Å
c/ Å
α/deg
β/deg
97.18(3)
90.00
γ/deg
V/ Å3
1611.0(6)
2
Z
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Crystal Growth & Design
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ρ (calcd)/Mg mꢀ3
1.290
1.291
1.303
5
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7
θ Range for data collection/° 1.40ꢀ25.41
1.65ꢀ25.38
410
1.82ꢀ25.37
466
F(000)
644
8
9
Ref collected/unique
R1, wR2(I >2σ(I))
R1, w R2 (all data)
Goodnessꢀofꢀfit,S
CCDC
3201/3201
0.0675, 0.0991
0.1640, 0.1236
1.008
3738/3737
0.0634, 0.1673
0.0986, 0.1875
1.001
4465/4199
0.0554, 0.1440
0.1008, 0.1781
1.016
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23
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25
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35
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1846584
1846583
1846585
Table.2
Crystal
DꢀH (Å)
H···A (Å)
D···A (Å)
∠DꢀH···A (°)
IA
C23ꢀH23A···N9
C35ꢀH35A···N7
C4ꢀH9A···N4
C26ꢀH26A···N2
C6ꢀH6A···N2
IIA
0.929
0.928
0.930
0.930
0.930
2.387
2.567
2.716
2.371
2.661
3.187
3.458
3.613
3.287
3.476
144
161
162
168
146
C8ꢀH8···N2
0.931
0.929
0.930
2.740
2.661
2.705
3.631
3.493
3.428
156
149
135
C10ꢀH10A···N3
C15ꢀH15A···N3
IIIA
C17ꢀH23A···N3
C3ꢀH3A···N2
C28ꢀH28A…N1
0.930
0.930
0.931
2.704
2.815
2.718
3.617
3.501
3.637
168
131
153
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Crystal Growth & Design
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Table. 3
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Crystal
Interaction
dπꢀπ, dcꢀc(Å)[a]
3.489, 3.688
3.331, 3.641
3.354, 3.546
3.477, 3.540
Angle (°) [b]
1.34
TCNB ··· Naphthalene
TCNB ···Benzene
TCNB ···Anthracene
TCNB ···Pyrene
IA
9
3.33
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
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58
59
60
7.64
IIA
1.33
IIIA
Table. 4
Crystals
NPA
APA
4.79
6.3
MPA
4.65
IA
IIA
IIIA
PLQY ΦF (%)
0.46
13.75
7.1
20.54
12.2
10.65
12.1
Fluorescence lifetime τF (ns)
4.99
2.04
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For Table of Contents use only
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Investigation of ChargeꢀTransfer Interaction modes in Mixed Stack DonorꢀAcceptor
Cocrystals Toward Tunable SolidꢀState Emission Characteristics
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Rabia Usman, Arshad Khan, Mingliang Wang Yi Luo, Weiwei Sun, Hao Sun, Cunbin Du,
Nongyue He
Synopsis
Charge transfer induced coꢀcrystallization between donorꢀacceptor (DꢀA) molecules resulted in
the formation of three mixed CT DꢀA cocrystals, which demonstrate excellent tunable emission
compared to the pristine donors
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