- Email: [email protected]
A theoretical study on electronic spectra of a novel series of metal substituted boron subphthalocyanine chloride
Journal Pre-proof A theoretical study on electronic spectra of a novel series of metal substituted boron subphthalocyanine chloride
Wenlan Chen, Suoping Peng, Shaohui Zheng PII:
S1386-1425(19)31417-9
DOI:
https://doi.org/10.1016/j.saa.2019.118018
Reference:
SAA 118018
To appear in:
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
Received date:
10 October 2019
Revised date:
16 December 2019
Accepted date:
27 December 2019
Please cite this article as: W. Chen, S. Peng and S. Zheng, A theoretical study on electronic spectra of a novel series of metal substituted boron subphthalocyanine chloride, Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy(2019), https://doi.org/10.1016/j.saa.2019.118018
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. 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.
© 2019 Published by Elsevier.
Journal Pre-proof
A theoretical study on electronic spectra of a novel series of metal substituted boron subphthalocyanine chloride Wenlan Chen†, Suoping Peng†, and Shaohui Zheng* Chongqing Key Laboratory for Advanced Materials and Technologies of Clean Energies School of Materials and Energy Southwest University, Chongqing, China †: co-first author Corresponding author: [email protected]
oo
f
Abstract: Boron subphthalocyanine chloride has been extensively studied by experimentalists and computational chemists due to its unique optical and electronic
pr
properties. It has been practical to modify the optical and physical properties of subphthalocyanine through axial, peripheral, and center substitutions or ring
e-
expansion. However, there have been few investigations on the substitution of central
Pr
boron atom. In the present work, a new metal-substituted (center substitution of boron atom) series of boron subphthalocyanine chloride (metal= Fe, Co, Ni, Cu, and Zn) are
al
theoretically designed utilizing modern density functional theory. The optimized results of this series in gas phase and with polarizable continuum model show that
rn
they may be chemically stable, and the predicted order of the stability of MSubPC is
Jo u
Fe>Cu>Ni>Co>Zn. Also, this new series of MSubPC molecules all becomes more non-planar and has much smaller dipole moments, which imply that they may be feasible for blend with organic acceptors. The HOMO-LUMO energy gaps of MSubPC (M=Co, Ni, Cu) are smaller than that of subPC. Furthermore, the wavelength of simulated absorption peaks of ZnSubPC and NiSubPC is red-shifted with respect to prototype subPC molecule in the visible region, and FeSubPC has noticeably stronger absorption strength than subPC because its excitation involves more orbital transitions and d electrons. The work here shows a new way to design photoelectric materials based on subphthalocyanine with center metal substitution. Keywords: boron subphthalocyanine; center metal substitution; excited state; electronic absorption spectroscopy; spin density; time-dependent density functional theory;
Journal Pre-proof
1. Introduction Since boron subphthalocyanine chloride (subPC), a cone-shaped organic molecule, was synthesized by Meller and Ossko in 1972,[1] this chemical compound and its derivatives have been extensively studied by experimentalists and computational chemists due to their excellency as optical and electronic materials.[2-5] Researchers keep changing the properties of subPC mainly through the substitution of axial chloride, edged hydrogen, and center boron atom.[6-8] Until now, researchers have made impressive progresses to apply subPC and its derivatives
f
to organic electronics.[7, 9, 10] [6, 11-16] [17, 18]
oo
In the past decades, numerous studies on the substitution of edged hydrogen and axial chloride atoms have been performed by researchers, which greatly expand the
pr
usage of subPC families.[2-5] However, there have been few investigations on the substitution of central boron atom. To date, only several theoretical studies are
e-
available.[17-21] Yang research group made theoretical analyses using atoms in
Pr
molecules（ AIM）and electron localization function (ELF) to predict how the substitution influence physical and optical properties, and aromaticity of MSubPc Al,
and
Ga)
through
density
functional
theory (DFT);[18,
19]
al
(M=B,
Montero-Campillo et al. applied density functional theory (DFT) and time dependent
rn
DFT (TDDFT) to study electronic structures and electronic absorption spectra of MSubPC (M=B, Al, Ga) and their derivatives,[17] and they further studied the
Jo u
photochemical behavior of beryllium complexes, i.e. beryllium substitutions of boron atom of subporphyrazines (BeSubPZ) and subphthalocyanines (BeSubPC).[21] It is well known that subPC molecule is the simplest homologue of phthalocyanine (PC) family.[22-25] PC has prodigious diversities because its huge ring cavity can contain up to seventy different atoms.[17] Unlike PC family, we realize that there are very few studies of substitution of boron atom centered at the ring cage of subPC, as previously discussed.[17-21] Therefore, this finding inspires us to replace boron atom of subPC with some often used metal atoms in PC family such as iron, copper, nickel, cobalt, and zinc atoms,[17, 18, 22-28] as shown in Figure 1.
Journal Pre-proof
Figure 1. The chemical structures of subPC and MSubPC (M=Fe, Co, Ni, Cu, Zn).
f
DFT and TDDFT have been extensively proved that they can reliably obtain
oo
reasonable molecular structures, and predict the properties of ground and excited state of PC and subPC families.[29-33] [31, 34-36] Therefore DFT and TDDFT are utilized to
pr
perform computational study of MSubPC (M=Fe, Co, Ni, Cu, Zn）monomer (see
e-
Figure 1).
The aims of the present work are two-fold:
Pr
1. To predict the stability of MSubPC (M=Fe, Co, Ni, Cu, Zn）molecules, their molecular geometry and ground-state electronic structures;
Jo u
rn
molecules.
al
2. To investigate the excited state properties of MSubPC (M=Fe, Co, Ni, Cu, Zn）
2. Computational Details All quantum computations were executed with Gaussian 09 Rev E.01 version software package.[37] Converge criteria were set to the default (N=8 for SCF; RMS force=3*10-4 for geometry optimization). The monomers of MSubPC were firstly optimized in gas phase to confirm their chemical stability. The spin multiplicities of both CoSubPC and CuSubPC were set to 2 (doublet), and the others were 1 (singlet state). Different multiplicities for these MSubPC were tested to make sure that the energy with these states is the minimum. The binding energy of a set of metal to SubPC was calculated, as shown in supporting information Table S0. These data confirm that the stability of MSubPC series is much less than porotype subPC, and the order of stability is Fe>Cu>Ni>Co>Zn. To simulate the environment in the thin film of organic solar cells or in solution,
Journal Pre-proof we applied an integral equation formalism (IEF) variant polarizable continuum model (PCM) for MSubPC monomers[38-40] The gas phase calculation for monomers were not carried out anymore because previous researches have demonstrated that the surrounding environment in condensed phase has significant influences on the electrical and optical properties of these organic molecules.[41-44] Didutylether solvent was chosen in PCM since its dielectric constant (ε=3.0473) is close to 3.0, which is often used to simulate the environment in organic solar cells.[42] Hybrid density functional B3LYP[45-47] with 6-31G(D) basis sets was selected for geometry optimization and frequency calculation since B3LYP density functional
oo
f
has been widely used for phthalocyanines and subphthalocyanine families.[48-50] 6-31G(D) basis set[51, 52] was chosen for all calculations because it has been widely used and proved to be capable to reproduce experimental structures and absorption
pr
spectra.[51-53]
e-
Long range corrected (LRC) density functionals CAM-B3LYP[54] and LC-ωPBE[55] were utilized for calculations of excited states. These state-of-the-art
Pr
density functionals can cure self-interaction error and derivative discontinuity problems of traditional DFT partly.[56] In gas phase, the HOMO/LUMO energy
al
obtained with these LRC density functionals is close to ionic potential (IP)/electronic affinity (EA) in principle. We optimized range separated parameter ω of LC-ωPBE in
rn
gas phase for every MSubPC molecule, as shown in SI Table S10. However, in
Jo u
condensed phase, the situation is complicated due to the surrounding environment (See Reference 53 and 56 for more details). IP/EA is not equal to the HOMO/LUMO energy obtained with LRC functionals in condensed phase anymore. Corrections were made to the HOMO/LUMO energy in condensed phase using the following equations[56]
𝑃𝐶𝑀 𝐺𝑎𝑠 𝜀𝐻𝑂𝑀𝑂 = 𝜀𝐻𝑂𝑀𝑂 + [𝐼𝑃𝐺𝑎𝑠 − 𝐼𝑃𝑃𝐶𝑀 ] 𝑃𝐶𝑀 𝐺𝑎𝑠 𝜀𝐿𝑈𝑀𝑂 = 𝜀𝐿𝑈𝑀𝑂 + [𝐸𝐴𝐺𝑎𝑠 − 𝐸𝐴𝑃𝐶𝑀 ]
（1） （2）
𝑃𝐶𝑀 𝑃𝐶𝑀 where 𝜀𝐻𝑂𝑀𝑂 and 𝜀𝐿𝑈𝑀𝑂 denote HOMO and LUMO energies in condensed phase, 𝐺𝑎𝑠 𝐺𝑎𝑠 respectively; 𝜀𝐻𝑂𝑀𝑂 /𝜀𝐿𝑈𝑀𝑂 represents HOMO/LUMO energy, which was calculated
with gas phase model, but the molecular geometry was optimized with PCM. It is worth pointing out that both CoSubPC and CuSubPC are open-shell (have one unpaired electron). And the energy of NiSubPC with different spin multiplicities (1 and 3) was calculated. The results show that the energy of NiSubPC with spin
Journal Pre-proof multiplicity of 3 is lower than that with spin multiplicity 1 (see Table S12). However, as shown in Table S0, the binding energy of NiSubPC with multiplicity of 1 is lower. Therefore we still chose NisubPC with spin multiplicity of 1 in the main manuscript. For comparisons, the ground- and excited state properties of NisubPC with spin multiplicity of 3 are also given out in SI Tables S0-5 and S7-11 and Figures S5-10. Note that SOMO (singly occupied molecular orbital) may be the better description than HOMO and LUMO for these molecules. However, for consistency, HOMO and LUMO are still used in the rest of this manuscript. To obtain insights into these molecules, natural bond orbital (NBO) analyses
oo
f
were performed with NBO Version 3.1[57] embedded in Gaussian software package. We simulated the UV-Vis spectra of monomer MSubPC based on the excited
pr
state calculations using traditional B3LYP and LRC CAM-B3LYP and LC-ωPBE density functionals, which have been proved to be able to reproduce experimental
e-
electronic absorption spectra.[58] Multiwfn software package was used to generate
Pr
absorption spectra.[59]
Based on the excited states of TDDFT calculation, the wavelength of simulated absorption peaks are given as following:
𝜆1 ∗𝑂𝑆1 +𝜆2 ∗𝑂𝑆2 +⋯+𝜆𝑛 ∗𝑂𝑆𝑛
al
𝜆𝑎𝑣𝑒 =
𝑂𝑆1 +𝑂𝑆2 +⋯+𝑂𝑆𝑛
(3)
rn
where 𝜆𝑛 /OSn is the wavelength/oscillator strength of the nth excited state,
Jo u
respectively; the subscript n is the nth excited states of TDDFT results within the half-width of a absorption peak. In this work, the energy of half-width of absorption peak was set to the default value 0.667 eV.[60] The cone height ‘h’ of MSubPC (as shown in Figure 2), which denotes the nonplanar property of subPC and its derivatives,[61] was computed with the following equation (а, β, θ, a, b are known geometry parameters )
Journal Pre-proof
ℎ12+ℎ22 −𝑐 2
h1=a×sinα; h2=b×sinβ; θ=arccos（
2ℎ1 ℎ2
）; h=h1×sinθ
（4）
oo
f
Figure 2. The cone height of MSubPC. M: metal atom, N: nitrogen atom, h: cone height.
pr
3. Results and discussion
e-
We initially give optimized geometry of MSubPC (M= Fe, Co, Ni, Cu, Zn) in gas phase. Then the ground and excited state properties in condensed phase, i.e. obtained
Pr
with PCM, are presented, since it is close to experimental condition and reality. Then the results of MSubPC monomer are discussed.
al
3.1. Geometry parameters.
rn
Firstly, all geometry optimizations of MSubPC (M= Fe, Co, Ni, Cu, Zn) monomers were run in gas phase. For simplicity and clarity, the geometry parameters
Jo u
including bond length, angles, and cone heights are listed in Supporting Information (SI) Table S1 and Figure S0. We find that all these monomers may be chemically stable according to the optimized results in gas phase. Of course, this may be not enough and synthesis experiments of these monomers are needed for further confirmation. Furthermore, since most of experimental structures are measured in the solid state or solution, we obtain the optimized geometry parameters of MSubPC (M=Fe, Co, Ni, Cu, Zn）monomers with PCM. The geometry parameters are given out in Table 1. The MSubPC molecules are quite different from the reference subPC since the B-Cl fragment is replaced with different metal atoms. However, the results of reference subPC molecule are still able to calibrate how the metal substitutions
Journal Pre-proof influence the geometries since the geometry parameters of subPC molecule have been extensively measured in the solid state.[62] As shown in Table 1 and Figure S0, B3LYP functional slightly overestimates the B-N bond length relative to experimental value of subPC. But, overall, the results match well with experimental data achieved with XRD technique in the solid state.[62] Therefore one can reasonably guess that the optimized geometry of MSubPC series is reliable since DFT calculations have been widely used to study organic metal complexes.[32] Table 1. The optimized geometry parameters of subPC and MSubPC (M= Fe, Co, Ni, Cu, Zn)
M-N2
M-N3
Exp
∠N1-X-N2
1.48
1.48
1.48
1.47
105.5
FeSubPC
1.80
1.80
1.80
N/A
90.0
CoSubPC
1.77
1.85
1.85
N/A
88.9
NiSubPC
1.82
1.73
1.82
N/A
CuSubPC
1.81
1.87
1.87
N/A
ZnSubPC
1.89
1.89
1.89
Cone Exp
Exp Height
105.5
105.2
0.58
0.59
90.1
90.0
N/A
1.02
N/A
88.9
93.4
N/A
1.02
N/A
90.4
90.6
108.5
N/A
0.90
N/A
90.8
96.7
90.8
N/A
1.02
N/A
91.8
91.7
N/A
1.06
N/A
al
91.6
rn
N/A
∠N1-X-N3
105.5
Pr
subPC
∠N2-X-N3
pr
M-N1
e-
System
oo
f
molecules and experimental structure of subPC. Unit: Å (length) and degree (angle).
The results in Table 1 demonstrate that the non-planarity of MSubPC series
Jo u
becomes stronger than subPC regarding the values of cone heights. One can see that the bond length between metal and nitrogen atoms is generally longer than that of boron-nitrogen bond of subPC, and the metal-involved angles in MSubPC are smaller than these in subPC molecule except for NiSubPC. Therefore the cone heights of MSubPC (M=Fe, Co, Ni, Cu, Zn）are much larger than that of subPC. This is reasonable because the radii of these metal atoms are much larger than that of boron atom. In MSubPC (M=Fe, Co, Ni, Cu, Zn）series, the symmetry is quite different. The spin multiplicities of both CoSubPC and CuSubPC are 2, and the others are 1. FeSubPC and ZnSubPC molecules have C3v symmetry. But MSubPC (M=Co, Ni, Cu) does not. The trigonal pyramidal molecular geometry (C3v) is not always consistent with spin multiplicity. This could be attributed to different electron configurations of d
Journal Pre-proof orbitals of metals, as shown in SI Table S2-S3. For example, in CoSubPC, there is a valence bonding between cobalt and one neighboring nitrogen atom; but for FeSubPC, NBO analyses only show that there are only three lone pair electrons on iron atom. FeSubPC and ZnSubPC have almost identical three angles ( ∠ N1-M-N2, ∠ N2-M-N3, and ∠N1-M-N3), just like subPC molecule. In contrast, in MSubPC (M=Co, Ni, Cu), one angle is always larger than other two similar ones and the deviation
is
at
least
4.5
degree.
The
trend
of
these
deviations
is
CoSubPC
oo
f
different electron configurations of d orbital and atomic radii of these metal atoms. We shall talk this later.
pr
Compared to the gas phase geometry, the results show that all bond length
e-
obtained with PCM is slightly shorter. But overall, the deviation is small than 0.2 angstrom.
Pr
3.2.Ground-state electronic structure, spin density, charge distribution, and dipole moment.
al
As shown in Table 2, the results of NBO analyses of these new molecules are
rn
listed. More details of NBO analyses and localized orbital locator (LOL) are available in SI Table S2-S5 and Figure S1, respectively. One can see that the natural charge of
Jo u
all metal atoms is close to 1.0, but their oxidation states should be about 2.0. We can reasonably conclude that the atomic orbitals of these metal2+ atoms, which are involved in the coordination with nitrogen atoms surrounding them, are mainly 3d, 4s, and 4p atomic orbitals. For example, in FeSubPC molecule, the electron configuration of the Fe2+ cation should be 3d6, however, due to electron back-donating of and covalent bonding with surrounding nitrogen atoms, the natural electron configuration of Fe2+ cation becomes 4s(0.19)3d(6.57)4p(0.13). Note that natural atomic charge of zinc in ZnSubPC is the most positive due to its 4s(0.31)3d(9.90)4p(0.36) configuration, whereas nickel atom of NiSubPC has the smallest positive value attributed to its 4s(0.24)3d(8.43)4p(0.31). In addition, the LOL figure demonstrates that the M-N bonding of all MSubPC seems to be more delocalized with respect to subPC.
Journal Pre-proof Table 2. NBO analyses of metal atoms in MSubPC molecules. System
Natural Charge
Natural Electron Configuration
Fe
1.12
[core]4s( 0.19)3d( 6.57)4p( 0.13)
Co
1.13
[core]4s( 0.19)3d( 7.46)4p( 0.22)
Ni
1.03
[core]4s( 0.24)3d( 8.43)4p( 0.31)
Cu
1.18
[core]4s( 0.25)3d( 9.23)4p( 0.34)
Zn
1.43
[core]4s( 0.31)3d( 9.90)4p( 0.36)
f
In Figure 3, we find that the electron density distribution of HOMOs of MSubPC
oo
(M=Fe, Co, Ni, Cu, Zn）are similar to that of the reference subPC molecule. In contrast, the LUMOs of MSubPC are quite different from subPC: the electron density
pr
distribution of LUMOs of MSubPC (M=Fe, Co, Ni) generally is close to metal atoms.
e-
Especially, the electron distribution of LUMOs of Co-SubPC and Ni-SubPC almost
Jo u
rn
al
Pr
locates on metal atom.
Figure 3. The frontier molecular orbitals of subPC and MSubPC (M= Fe, Co, Ni, Cu, Zn) molecules, obtained with B3LYP/6-31G(D)/PCM theory level. Iso-surface value: 0.03 a.u.
Journal Pre-proof Figure 4. The energy of frontier molecular orbitals of subPC and MSubPC (M= Fe, Co, Ni, Cu, Zn) molecules obtained with B3LYP (half-mark for clarity), CAM-B3LYP and LC-ωPBE (with optimized ω). The latter two are corrected with Equation 1 and 2. The color of code: black－CAM-B3LYP, green －LC-ωPBE, and red－B3LYP.
In Figure 4, one can see that the HOMO energy of MSubPC series is higher than that of subPC in all three functionals, except for ZnSubPC. The LUMO (SOMO) energy and energy gap of CuSubPC is noticeably lower than that of subPC and other MSubPCs. The results also indicate that the corrected CAM-B3LYP HOMO/LUMO
oo
f
energies and energy gap (available in SI Table S6) generally are close to B3LYP uncorrected results compared to LC-ωPBE functional, except for NiSubPC. As we
pr
talked in Computational Details, the HOMO/LUMO energy obtained with B3LYP
e-
density functional has no physical meaning since they cannot satisfy Koopman theorem.[8, 63, 64] This is just a coincidence because of error cancelation. The energy
Pr
gaps obtained with LC-ωPBE are generally larger than CAM-B3LYP ones, except for CoSubPC, which can be attributed to different intrinsic LRC DFT kernel. This finding
Jo u
rn
al
is consistent with the previous researches.[42]
Figure 5. The spin density of CoSubPC and CuSubPC molecules obtained with B3LYP/6-31G(D)/PCM theory level. Iso-surface value: 0.03 a.u.
Table 3. Metal or boron atomic Mulliken charge and spin density of subPC and MSubPC, obtained with B3LYP/6-31G(D)/PCM theory level. Spin: spin multiplicity. System (spin)
M or B
Spin density
SubPC (1)
0.52
N/A
Journal Pre-proof FeSubPC (1)
1.10
N/A
CoSubPC (2)
1.05
0.99
NiSubPC (1)
0.90
N/A
CuSubPC (2)
0.95
0.67
ZnSubPC (1)
1.09
N/A
Next, the Mulliken charges of different center (boron and M) atoms of subPC and MSubPC series are presented in Table 3 because the dipole moments of these
f
molecules are based on Mulliken charges, not natural atomic charges. The metal
oo
atoms of MSubPC have much larger values of positive charge than B atom of subPC. The order of positive charges of metal atoms is Ni
pr
also list the data of dipole moments of subPC and MSubPC series in SI Table S7 and
e-
Figure S2. Compared to subPC, all MSubPC molecules have much smaller dipole moments because of the lack of chloride atom. It is not surprised the trend of dipole
Pr
moments is exactly same as that of positive charges of metal atoms of MSubPC, that is, Ni
al
Finally, spin density of CoSubPC and CuSubPC molecules with unpaired
rn
electrons is shown in Figure 5 and Table 3. Unpaired electron of cobalt or copper atom is not localized anymore. And the spin density (0.67) of copper atom is smaller
Jo u
than that (0.99) of cobalt atom, which means the unpaired electron of copper atom delocalizes more than that of cobalt. 3.3.Absorption spectrum.
The simulated absorption spectra of MSubPC monomers and subPC molecule, achieved with LC-ωPBE/6-31G(D)/PCM level, are shown in Figure 6 (for simplicity, see SI Figure S3 and S4 for CAM-B3LYP and B3LYP results) since LC-ωPBE functional is able to reproduce subPC absorption spectrum well.[65, 66] Similar to subPC molecule, all metal-substituted monomers demonstrate strong absorption strength in the visible region. Interestingly, FeSubPC has even a wider absorption range (320-700 nm) than subPC and other MSubPC (see Figure 6 and SI Figure S3-4).
pr
oo
f
Journal Pre-proof
Figure 6. The simulated electronic absorption (ranged from 300 to 800 nm) spectra of subPC and
e-
MSubPC (M= Fe, Co, Ni, Cu, Zn) molecules based on tuned LC-ωPBE/6-31G* with PCM.
Pr
The total oscillator strength and averaged absorption wavelength of MSubPC series and subPC molecule are summarized in Figure 7 (see SI Table S8a-8b for data).
al
It indicates that only FeSubPC has stronger absorption strength than subPC molecule in the visible region in MSubPC series. The trends of wavelength and oscillator
rn
strength of B3LYP and CAM-B3LYP are basically same. The absorption peaks
Jo u
(averaged wavelength) of ZnSubPC and NiSubPC are red-shifted compared to subPC molecule in the results of all three functionals. In addition, we find that the wavelength of absorption peak of CuSubPC, obtained with CAM-B3LYP, is noticeably blue-shifted.
e-
pr
oo
f
Journal Pre-proof
Figure 7. The averaged absorption wavelength and oscillator strength of MSubPC monomers and
Pr
subPC molecule.
In Figure 8, the transition densities of electron-hole plots of the first absorption
al
state of subPC and MSubPC series with strong oscillator strength are drawn. Basically,
rn
the excitations are π to π* transitions of conjugate aromatic rings. However, for FeSubPC and CoSubPC, the d orbitals of metal atoms are partly involved in the
Jo u
excitations. We further make orbital analyses (see SI Table S9 for details). Overall, the orbitals transitions between HOMO-4 to HOMO and LUMO to LUMO+4 are dominant in these excitations.
Figure 8. The electron-hole densities for the transitions of the first bright (oscillator strength >0.1) excited state of subPC and MSubPC (M= Fe, Co, Ni, Cu, Zn) molecules based on LC-ωPBE /6-31G*
Journal Pre-proof with PCM. The color of code: blue-hole, green-electron. Iso-surface value: 0.003 a.u.
4. Conclusions In summary, MSubPC series has been theoretically proved that they may be chemically stable in gas phase and condensed phase. The calculated binding energy of MSubPC confirm that the order of stability is Fe>Cu>Ni>Co>Zn, and they are much less stable than prototype subPC. In addition, the optimized geometry parameters
f
show that these MSubPC molecules are more non-planar than subPC. Compared to
oo
subPC, all MSubPC molecules also have much smaller dipole moments because of the lack of chloride atom. These results imply that MSubPC series may be feasible for
pr
mixing them with donor materials. Furthermore, we find that the wavelength of
e-
absorption peaks of ZnSubPC and NiSubPC are red-shifted compared to subPC molecule in the results of all three functionals, and especially FeSubPC has even
Pr
stronger absorption strength than subPC in the visible region because its excitation involves more orbital transitions and d electrons. The work here shows a new way to
al
design photoelectric materials based on subphthalocyanine with center metal
Jo u
subPC.
rn
substitution. All these findings suggest a new strategy of designing metal-substituted
In the future, we plan to find some superior metals or non-metal atoms since its homologue phthalocyanine has remarkable diversities and the cavity of PC can contain up to seventy different atoms.
Acknowledgements We greatly thank for valuable suggestions from Ms. Xue Chen and Ms. Wenjing Wang. We also appreciate Fundamental Research Funds for the Central Universities (XDJK2016A016, XDJK2016E014, XDJK2017D015, and XDJK2017D019) and Start-up funding from Southwest University (SWU117018). S.Z. also thanks the financial support from the Start-up Funding for Young Faculty of Southwest University. This project is also supported by Program for Innovation Team Building at
Journal Pre-proof Institutions of Higher Education in Chongqing（CXTDX201601011）.
References [1] A.M.A. 0ssko, Phthalocyaninartige Bor-Komplexe, Monatsh. Chem. , 103 (1972) 150-155. [2] C.G. Claessens, D. Gonzalez-Rodriguez, M.S. Rodriguez-Morgade, A. Medina, T. Torres, Subphthalocyanines, subporphyrazines, and subporphyrins: singular nonplanar aromatic systems, Chem Rev, 114 (2014) 2192-2277. [3] Y. Lin, Y. Li, X. Zhan, Small molecule semiconductors for high-efficiency organic photovoltaics, Chem Soc Rev, 41 (2012) 4245-4272. [4] K.A. Mazzio, C.K. Luscombe, The future of organic photovoltaics, Chem Soc Rev, 44 (2015)
f
78-90.
oo
[5] A. Mishra, P. Bauerle, Small molecule organic semiconductors on the move: promises for future solar energy technology, Angew Chem Int Ed Engl, 51 (2012) 2020-2067.
pr
[6] C. Duan, G. Zango, M. Garcia Iglesias, F.J. Colberts, M.M. Wienk, M.V. Martinez-Diaz, R.A. Janssen, T. Torres, The Role of the Axial Substituent in Subphthalocyanine Acceptors for Bulk-Heterojunction Solar Cells, Angew Chem Int Ed Engl, 56 (2017) 148-152.
e-
[7] H. Gommans, T. Aernouts, B. Verreet, P. Heremans, A.s. Medina, C.G. Claessens, T. Torres, Perfluorinated Subphthalocyanine as a New Acceptor Material in a Small-Molecule Bilayer
Pr
Organic Solar Cell, Adv Funct Mater, 19 (2009) 3435-3439. [8] O.V. Gritsenko, Koopmans’ theorem and its density-functional-theory analog assessed in evaluation of the red shift of vertical ionization potential upon complexation, Chem Phys Lett, 691 (2018)
al
178-180.
[9] C.B. Kc, G.N. Lim, F. D'Souza, Tuning Optical and Electron Donor Properties by Peripheral
rn
Thio-Aryl Substitution of Subphthalocyanine: A New Series of Donor-Acceptor Hybrids for Photoinduced Charge Separation, Chemistry, 22 (2016) 13301-13311.
Jo u
[10] H. Lee, S.W. Ahn, S.H. Ryu, B.K. Ryu, M.H. Lee, S.W. Cho, K.E. Smith, T.S. Jones, Interfacial electronic structure of Cl6SubPc non-fullerene acceptors in organic photovoltaics using soft X-ray spectroscopies, Phys Chem Chem Phys, 19 (2017) 31628-31633. [11] J. Guilleme, D. Gonzalez-Rodriguez, T. Torres, Triflate-subphthalocyanines: versatile, reactive intermediates for axial functionalization at the boron atom, Angew Chem Int Ed Engl, 50 (2011) 3506-3509. [12] J. Guilleme, L. Martinez-Fernandez, I. Corral, M. Yanez, D. Gonzalez-Rodriguez, T. Torres, Direct Access to Axially Substituted Subphthalocyanines from Trimethylsilyl-Protected Nucleophiles, Org Lett, 17 (2015) 4722-4725. [13] S. Kalia, A. Mahajan, C.G. Ghansyam, A.K. Debnath, V. Saxsena, D.K. Aswal, R.K. Bedi, Anisotropic charge transport properties in boron sub phthalocyanine chloride thin films, J Appl Phys, 121 (2017) 095501. [14] E. Maligaspe, M.R. Hauwiller, Y.V. Zatsikha, J.A. Hinke, P.V. Solntsev, D.A. Blank, V.N. Nemykin, Redox and photoinduced electron-transfer properties in short distance organoboryl ferrocene-subphthalocyanine dyads, Inorg Chem, 53 (2014) 9336-9347. [15] R. Menting, D.K. Ng, B. Roder, E.A. Ermilov, Sequential energy and charge transfer processes in mixed host-guest complexes of subphthalocyanine, porphyrin and phthalocyanine chromophores,
Journal Pre-proof Phys Chem Chem Phys, 14 (2012) 14573-14584. [16] Z. Wang, X. Fu, Synthesis, Characterization, and Reactivity Studies of Subphthalocyanine Boron Triflate, Organometallics, 36 (2017) 285-290. [17] M.M. Montero-Campillo, A.M. Lamsabhi, O. Mo, M. Yanez, UV/Vis spectra of Subporphyrazines and Subphthalocyanines with Aluminum and Gallium: a Time-Dependent DFT Study, ChemPhyschem, 14 (2013) 915-922. [18] Y. Yang, Metal–ligand coordination in subphthalocyanines and phthalocyanines: DFT, AIM and ELF analyses, Polyhedron, 33 (2012) 310-318. [19] Y.J. Yang, Z.M. Su, Structure, stability, and aromaticity of M-SubPc (M=B, Al, and Ga): Computational study, Int J Quantum Chem, 103 (2005) 54-59. [20] J.H.Y. Daocheng X, Qing Long B, Chuanhui Cheng, Peng X, Lifeng L, Zhaoqi F, Guotong D ＊,
f
Synthesis and Characterization of Subphthalocyanine Copper, Journal of Shanxi University
oo
(Natural Science Edition), (2009) 426-431.
[21] M.M. Montero-Campillo, A.M. Lamsabhi, O. Mo, M. Yanez, Photochemical Behavior of
pr
Beryllium Complexes with Subporphyrazines and Subphthalocyanines, J Phys Chem A, 120 (2016) 4845-4852.
[22] X. Ji, T. Zou, H. Gong, Q. Wu, Z. Qiao, W. Wu, H. Wang, Cobalt phthalocyanine nanowires:
e-
Growth, crystal structure, and optical properties, Cryst Res Techol, 51 (2016) 154-159. [23] S. Kaipova, H. Dinçer, A. Altindal, Synthesis, characterization, conduction, and dielectric
Pr
properties of tetratert-butylsulfanyl substituted phthalocyanines, J Coord Chem, 68 (2014) 717-731.
[24] P. Muthukumar, H.-S. Kim, J.W. Jeong, Y.-A. Son, Synthesis and characterization of tetra
al
phenoxy-substituted halogen-rich metallophthalocyanine derivatives: A study on their LCD color filter requirements, J Mol Struct, 1119 (2016) 325-331.
rn
[25] Z. Wang, R. Wei, X. Liu, Preparation and dielectric properties of copper phthalocyanine/graphene oxide nanohybrids via in situ polymerization, J Mater Sci, 51 (2016) 4682-4690.
Jo u
[26] A. Banerjee, B. Kundu, A.J. Pal, Introducing immobilized metal phthalocyanines as spin-injection and detection layers in organic spin-valves: Spin-tunneling and spin-transport regimes, Org Electron, 41 (2017) 173-178.
[27] M. Yıldırım, O. Köysal, G. Önsal, E. Gümüş, Effect of iron phthalocyanine (FePc) concentration on electrical and dielectric properties of the nematic liquid crystal composites, J Mol Liq, 223 (2016) 868-872. [28] N. Heo, Y. Kim, Y. Jung, S. Cheon, S. Cho, S.W. Cho, S. Park, Y. Yi, K.E. Smith, Interfacial electronic structure of C 60 /ZnPc/AZO on photoemission spectroscopy for organic photovoltaic applications, Chem Phys, 478 (2016) 145-149. [29] M.-S. Liao, S. Scheiner, Electronic structure and bonding in metal phthalocyanines, Metal=Fe, Co, Ni, Cu, Zn, Mg, J Chem Phys, 114 (2001) 9780-9791. [30] Z. Liu, Z.-X. Chen, B. Jin, X. Zhang, Theoretical studies on the structures and vibrational spectra of Ni, Pd, and Pt phthalocyanines, Vib. Spectrosc, 56 (2011) 210-218. [31] Y. Gao, P.V. Solntsev, V.N. Nemykin, Comparative electronic structures and UV-vis spectra of tribenzosubporphyrin,
tribenzomonoazasubporphyrin,
tribenzodiazasubporphyrin,
and
subphthalocyanine: insight from DFT and TDDFT calculations, J Mol Graph Model, 38 (2012) 369-374.
Journal Pre-proof [32] Y.J. Yang, Y.H. Kan, Z.M. Su, L. Zhao, Theoretical study on stability and nonlinear optical properties of novel subphthalocyanine dimer and trimer, J Mol Struc-Theochem, 725 (2005) 127-131. [33] D. Zdravkovski, M.C. Milletti, A comparison of structural and electronic characteristics among subphthalocyanine and phthalocyanine complexes, J Mol Struc-Theochem, 717 (2005) 85-89. [34] L.A. Leal, W.F. da Cunha, L.A. Ribeiro Junior, T.L. Pereira, S.M. Blawid, R.T. de Sousa Junior, D.A. da Silva Filho, Optical and electronic structure description of metal-doped phthalocyanines, J Mol Model, 23 (2017) 172. [35] C. Azarias, M. Pawelek, D. Jacquemin, Structural and Optical Properties of Subporphyrinoids: A TD-DFT Study, J Phys Chem A, 121 (2017) 4306-4317. [36] A. Dreuw, Long-range charge-transfer excited states in time-dependent density functional theory require non-local exchange, J Chem Phys, 119 (2003) 2943-2946.
f
[37] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman, G. Scalmani,
oo
V. Barone, B. Mennucci, G.A. Petersson, H. Nakatsuji, M. Caricato, X.H. Li, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.;
pr
Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A., Jr.; Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.;
e-
Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, N. J.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.;
Pr
Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, Ö.; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J., in, Gaussian Inc., Wallingford CT, 2009.
al
[38] E. Cancès, B. Mennucci, J. Tomasi, A new integral equation formalism for the polarizable continuum model: Theoretical background and applications to isotropic and anisotropic dielectrics,
rn
J Chem Phys, 107 (1997) 3032-3041.
[39] A.W. Lange, J.M. Herbert, A smooth, nonsingular, and faithful discretization scheme for 244111.
Jo u
polarizable continuum models: the switching/Gaussian approach, J Chem Phys, 133 (2010) [40] A.W. Lange, J.M. Herbert, Symmetric versus asymmetric discretization of the integral equations in polarizable continuum solvation models, Chem Phys Lett, 509 (2011) 77-87. [41] S.H. Zheng, M.Y. Xiao, Y.P. Tian, X. Chen, Prediction of the lowest charge-transfer excited-state energy at the donor-acceptor interface in a condensed phase using ground-state DFT calculations with generalized Kohn-Sham functionals, J. Mol. Model., 23 (2017) 235. [42] M.Y. Xiao, Y.P. Tian, S.H. Zheng, An insight into the relationship between morphology and open circuit
voltage/electronic
absorption
spectrum
at
donor-acceptor
interface
in
boron
subphthalocyanine chloride/C70 solar cell: A DFT/TDDFT exploration, Org. Electron., 59 (2018) 279-287. [43] H. Phillips, S. Zheng, A. Hyla, R. Laine, T. Goodson, 3rd, E. Geva, B.D. Dunietz, Ab initio calculation of the electronic absorption of functionalized octahedral silsesquioxanes via time-dependent density functional theory with range-separated hybrid functionals, J Phys Chem A, 116 (2012) 1137-1145. [44] S.H. Zheng, H. Phillips, E. Geva, B.D. Dunietz, Ab Initio Study of the Emissive Charge-Transfer States of Solvated Chromophore-Functionalized Silsesquioxanes, J. Am. Chem. Soc., 134 (2012)
Journal Pre-proof 6944-6947. [45] A.D. Becke, DENSITY-FUNCTIONAL EXCHANGE-ENERGY APPROXIMATION WITH CORRECT ASYMPTOTIC-BEHAVIOR, Phys. Rev. A 38 (1988) 3098-3100. [46] A.D. Becke, Density‐functional thermochemistry. III. The role of exact exchange, J Chem Phys, 98 (1993) 5648-5652. [47] B. Miehlich, A. Savin, H. Stoll, H. Preuss, RESULTS OBTAINED WITH THE CORRELATION-ENERGY DENSITY FUNCTIONALS OF BECKE AND LEE, YANG AND PARR, Chem Phys Lett, 157 (1989) 200-206. [48]
M.E.
El-Khouly,
Electron
transfer
naphthalocyanine-subphthalocyanine
reaction
self-assembled
of
dyad:
light
harvesting
spectroscopic,
zinc
electrochemical,
computational, and photochemical studies, Phys Chem Chem Phys, 12 (2010) 12746-12752. [49] M.E. El-Khouly, D.K. Ju, K.Y. Kay, F. D'Souza, S. Fukuzumi, Supramolecular Tetrad of Porphyrin
Coordinated
to
f
Subphthalocyanine-Triphenylamine-Zinc
Fullerene
as
an
Nonpolar Solvent, Chem-Eur J, 16 (2010) 6193-6202.
oo
"Antenna-Reaction-Center" Mimic: Formation of a Long-Lived Charge-Separated State in
pr
[50] Z.Q. Liu, X.X. Zhang, Y.X. Zhang, J.Z. Jiang, Theoretical investigation of the molecular, electronic structures and vibrational spectra of a series of first transition metal phthalocyanines, S.A.P:M&B.S, 67 (2007) 1232-1246.
e-
[51] G.A. Petersson, M.A. Al‐Laham, A complete basis set model chemistry. II. Open‐shell systems and the total energies of the first‐row atoms, J Chem Phys, 94 (1991) 6081-6090.
Pr
[52] G.A. Petersson, A. Bennett, T.G. Tensfeldt, M.A. Al‐Laham, W.A. Shirley, J. Mantzaris, A complete basis set model chemistry. I. The total energies of closed‐shell atoms and hydrides of the first‐row elements, J Chem Phys, 89 (1988) 2193-2218.
al
[53] H. Phillips, S.H. Zheng, E. Geva, B. Dunietz, Predictive computational methods for charge transfer in organic optoelectronic materials, Amer. Chemical Soc., 246 (2013).
rn
[54] T. Yanai, D.P. Tew, N.C. Handy, A new hybrid exchange–correlation functional using the Coulomb-attenuating method (CAM-B3LYP), Chem Phys Lett, 393 (2004) 51-57.
Jo u
[55] T.M. Henderson, A.F. Izmaylov, G. Scalmani, G.E. Scuseria, Can short-range hybrids describe long-range-dependent properties?, J Chem Phys, 131 (2009) 044108. [56] H. Phillips, Z. Zheng, E. Geva, B.D. Dunietz, Orbital gap predictions for rational design of organic photovoltaic materials, Org Electron, 15 (2014) 1509-1520. [57] A.E.R. E. D. Glendening, J. E. Carpenter, and F. Weinhold, NBO Version 3.1. [58] X. Chen, W.L. Chen, S.H. Zheng, Reproduction of the UV-vis spectra of boron subphthalocyanine chloride in different solvents using time-dependent generalized Kohn–Sham density functionals with first solvation shell, J Porphyr Phthalocya, 22 (2018) 670-678. [59] T. Lu, F. Chen, Multiwfn: a multifunctional wavefunction analyzer, J Comput Chem, 33 (2012) 580-592. [60] S. Peng, S. Zheng, A computational investigation on core‐expanded subphthalocyanines, Int. J. Quantum Chem, (2019) e25942. [61] K. Kasuga, T. Idehara, M. Handa, Y. Ueda, T. Fujiwara, K. Isa, Structure and some properties of (alkoxo)(subphthalocyaninato)boron(III), Bull. Chem. Soc. Jpn., 69 (1996) 2559-2563. [62]
H.
Kietaibl,
CRYSTAL
AND
MOLECULAR-STRUCTURE
OF
A
NEW
PHTHALOCYANINE-LIKE BORON COMPLEX, Monatsh. Chem., 105 (1974) 405-418. [63] A. Dreuw, M. Head-Gordon, Failure of time-dependent density functional theory for long-range
Journal Pre-proof charge-transfer
excited
states:
The
zincbacteriochlorin-bacterlochlorin
and
bacteriochlorophyll-spheroidene complexes, J. Am. Chem. Soc., 126 (2004) 4007-4016. [64] S. Hirata, C.G. Zhan, E. Apra, T.L. Windus, D.A. Dixon, A new, self-contained asymptotic correction scheme to exchange-correlation potentials for time-dependent density functional theory, J. Phys. Chem. A, 107 (2003) 10154-10158. [65] Y.D. Zhao, J.J. Fu, H.B. Li, H. Dong, Y. Liao, Photoinduced charge transfer processes of zinc porphyrin derivatives for dye-sensitized solar cells, Chem. Res. Chinese U., 29 (2013) 974-981. [66] X. Chen, S. Zheng, Inferring the molecular arrangements of boron subphthalocyanine chloride in thin film from a DFT/TDDFT study of molecular clusters and experimental electronic absorption spectra, Org Electron, 62 (2018) 667-675.
f
Author Contribution
oo
Conceptualization：Shaohui Zheng
pr
Data curation：Wenlan Chen; Suoping Peng
Pr
Funding acquisition： Shaohui Zheng
e-
Formal analysis： Shaohui Zheng; Wenlan Chen; Suoping Peng
Investigation：Shaohui Zheng; Wenlan Chen
al
Methodology：Shaohui Zheng; Wenlan Chen
rn
Project administration：Shaohui Zheng
Jo u
Resources：Shaohui Zheng Software：Shaohui Zheng
Supervision：Shaohui Zheng Validation：Shaohui Zheng Visualization：Wenlan Chen; Suoping Peng Roles/Writing - original draft：Wenlan Chen; Writing - review & editing：Shaohui Zheng
Journal Pre-proof Declaration of Competing Interest There are no conflicts to declare.
Jo u
Highlights
rn
al
Pr
e-
pr
oo
f
Graphical abstract
By modeling MSubPC through center metal substitutions (metal= Fe, Co, Ni, Cu, and Zn) of subPC, the calculated results show that MSubPC series may be chemically stable, and the predicted order of the stability of MSubPC is Fe>Cu>Ni>Co>Zn. Also, this new series of MSubPC molecules all becomes more non-planar and has much smaller dipole moments than subPC, which imply that they may be feasible for blend with organic acceptors. The HOMO-LUMO energy gaps of MSubPC (M=Co, Ni, Cu) are smaller than that of subPC. Furthermore, FeSubPC has noticeably stronger absorption strength than subPC because its excitation involves more orbital transitions and d electrons.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Wenlan Chen, Suoping Peng, Shaohui Zheng PII:
S1386-1425(19)31417-9
DOI:
https://doi.org/10.1016/j.saa.2019.118018
Reference:
SAA 118018
To appear in:
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
Received date:
10 October 2019
Revised date:
16 December 2019
Accepted date:
27 December 2019
Please cite this article as: W. Chen, S. Peng and S. Zheng, A theoretical study on electronic spectra of a novel series of metal substituted boron subphthalocyanine chloride, Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy(2019), https://doi.org/10.1016/j.saa.2019.118018
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. 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.
© 2019 Published by Elsevier.
Journal Pre-proof
A theoretical study on electronic spectra of a novel series of metal substituted boron subphthalocyanine chloride Wenlan Chen†, Suoping Peng†, and Shaohui Zheng* Chongqing Key Laboratory for Advanced Materials and Technologies of Clean Energies School of Materials and Energy Southwest University, Chongqing, China †: co-first author Corresponding author: [email protected]
oo
f
Abstract: Boron subphthalocyanine chloride has been extensively studied by experimentalists and computational chemists due to its unique optical and electronic
pr
properties. It has been practical to modify the optical and physical properties of subphthalocyanine through axial, peripheral, and center substitutions or ring
e-
expansion. However, there have been few investigations on the substitution of central
Pr
boron atom. In the present work, a new metal-substituted (center substitution of boron atom) series of boron subphthalocyanine chloride (metal= Fe, Co, Ni, Cu, and Zn) are
al
theoretically designed utilizing modern density functional theory. The optimized results of this series in gas phase and with polarizable continuum model show that
rn
they may be chemically stable, and the predicted order of the stability of MSubPC is
Jo u
Fe>Cu>Ni>Co>Zn. Also, this new series of MSubPC molecules all becomes more non-planar and has much smaller dipole moments, which imply that they may be feasible for blend with organic acceptors. The HOMO-LUMO energy gaps of MSubPC (M=Co, Ni, Cu) are smaller than that of subPC. Furthermore, the wavelength of simulated absorption peaks of ZnSubPC and NiSubPC is red-shifted with respect to prototype subPC molecule in the visible region, and FeSubPC has noticeably stronger absorption strength than subPC because its excitation involves more orbital transitions and d electrons. The work here shows a new way to design photoelectric materials based on subphthalocyanine with center metal substitution. Keywords: boron subphthalocyanine; center metal substitution; excited state; electronic absorption spectroscopy; spin density; time-dependent density functional theory;
Journal Pre-proof
1. Introduction Since boron subphthalocyanine chloride (subPC), a cone-shaped organic molecule, was synthesized by Meller and Ossko in 1972,[1] this chemical compound and its derivatives have been extensively studied by experimentalists and computational chemists due to their excellency as optical and electronic materials.[2-5] Researchers keep changing the properties of subPC mainly through the substitution of axial chloride, edged hydrogen, and center boron atom.[6-8] Until now, researchers have made impressive progresses to apply subPC and its derivatives
f
to organic electronics.[7, 9, 10] [6, 11-16] [17, 18]
oo
In the past decades, numerous studies on the substitution of edged hydrogen and axial chloride atoms have been performed by researchers, which greatly expand the
pr
usage of subPC families.[2-5] However, there have been few investigations on the substitution of central boron atom. To date, only several theoretical studies are
e-
available.[17-21] Yang research group made theoretical analyses using atoms in
Pr
molecules（ AIM）and electron localization function (ELF) to predict how the substitution influence physical and optical properties, and aromaticity of MSubPc Al,
and
Ga)
through
density
functional
theory (DFT);[18,
19]
al
(M=B,
Montero-Campillo et al. applied density functional theory (DFT) and time dependent
rn
DFT (TDDFT) to study electronic structures and electronic absorption spectra of MSubPC (M=B, Al, Ga) and their derivatives,[17] and they further studied the
Jo u
photochemical behavior of beryllium complexes, i.e. beryllium substitutions of boron atom of subporphyrazines (BeSubPZ) and subphthalocyanines (BeSubPC).[21] It is well known that subPC molecule is the simplest homologue of phthalocyanine (PC) family.[22-25] PC has prodigious diversities because its huge ring cavity can contain up to seventy different atoms.[17] Unlike PC family, we realize that there are very few studies of substitution of boron atom centered at the ring cage of subPC, as previously discussed.[17-21] Therefore, this finding inspires us to replace boron atom of subPC with some often used metal atoms in PC family such as iron, copper, nickel, cobalt, and zinc atoms,[17, 18, 22-28] as shown in Figure 1.
Journal Pre-proof
Figure 1. The chemical structures of subPC and MSubPC (M=Fe, Co, Ni, Cu, Zn).
f
DFT and TDDFT have been extensively proved that they can reliably obtain
oo
reasonable molecular structures, and predict the properties of ground and excited state of PC and subPC families.[29-33] [31, 34-36] Therefore DFT and TDDFT are utilized to
pr
perform computational study of MSubPC (M=Fe, Co, Ni, Cu, Zn）monomer (see
e-
Figure 1).
The aims of the present work are two-fold:
Pr
1. To predict the stability of MSubPC (M=Fe, Co, Ni, Cu, Zn）molecules, their molecular geometry and ground-state electronic structures;
Jo u
rn
molecules.
al
2. To investigate the excited state properties of MSubPC (M=Fe, Co, Ni, Cu, Zn）
2. Computational Details All quantum computations were executed with Gaussian 09 Rev E.01 version software package.[37] Converge criteria were set to the default (N=8 for SCF; RMS force=3*10-4 for geometry optimization). The monomers of MSubPC were firstly optimized in gas phase to confirm their chemical stability. The spin multiplicities of both CoSubPC and CuSubPC were set to 2 (doublet), and the others were 1 (singlet state). Different multiplicities for these MSubPC were tested to make sure that the energy with these states is the minimum. The binding energy of a set of metal to SubPC was calculated, as shown in supporting information Table S0. These data confirm that the stability of MSubPC series is much less than porotype subPC, and the order of stability is Fe>Cu>Ni>Co>Zn. To simulate the environment in the thin film of organic solar cells or in solution,
Journal Pre-proof we applied an integral equation formalism (IEF) variant polarizable continuum model (PCM) for MSubPC monomers[38-40] The gas phase calculation for monomers were not carried out anymore because previous researches have demonstrated that the surrounding environment in condensed phase has significant influences on the electrical and optical properties of these organic molecules.[41-44] Didutylether solvent was chosen in PCM since its dielectric constant (ε=3.0473) is close to 3.0, which is often used to simulate the environment in organic solar cells.[42] Hybrid density functional B3LYP[45-47] with 6-31G(D) basis sets was selected for geometry optimization and frequency calculation since B3LYP density functional
oo
f
has been widely used for phthalocyanines and subphthalocyanine families.[48-50] 6-31G(D) basis set[51, 52] was chosen for all calculations because it has been widely used and proved to be capable to reproduce experimental structures and absorption
pr
spectra.[51-53]
e-
Long range corrected (LRC) density functionals CAM-B3LYP[54] and LC-ωPBE[55] were utilized for calculations of excited states. These state-of-the-art
Pr
density functionals can cure self-interaction error and derivative discontinuity problems of traditional DFT partly.[56] In gas phase, the HOMO/LUMO energy
al
obtained with these LRC density functionals is close to ionic potential (IP)/electronic affinity (EA) in principle. We optimized range separated parameter ω of LC-ωPBE in
rn
gas phase for every MSubPC molecule, as shown in SI Table S10. However, in
Jo u
condensed phase, the situation is complicated due to the surrounding environment (See Reference 53 and 56 for more details). IP/EA is not equal to the HOMO/LUMO energy obtained with LRC functionals in condensed phase anymore. Corrections were made to the HOMO/LUMO energy in condensed phase using the following equations[56]
𝑃𝐶𝑀 𝐺𝑎𝑠 𝜀𝐻𝑂𝑀𝑂 = 𝜀𝐻𝑂𝑀𝑂 + [𝐼𝑃𝐺𝑎𝑠 − 𝐼𝑃𝑃𝐶𝑀 ] 𝑃𝐶𝑀 𝐺𝑎𝑠 𝜀𝐿𝑈𝑀𝑂 = 𝜀𝐿𝑈𝑀𝑂 + [𝐸𝐴𝐺𝑎𝑠 − 𝐸𝐴𝑃𝐶𝑀 ]
（1） （2）
𝑃𝐶𝑀 𝑃𝐶𝑀 where 𝜀𝐻𝑂𝑀𝑂 and 𝜀𝐿𝑈𝑀𝑂 denote HOMO and LUMO energies in condensed phase, 𝐺𝑎𝑠 𝐺𝑎𝑠 respectively; 𝜀𝐻𝑂𝑀𝑂 /𝜀𝐿𝑈𝑀𝑂 represents HOMO/LUMO energy, which was calculated
with gas phase model, but the molecular geometry was optimized with PCM. It is worth pointing out that both CoSubPC and CuSubPC are open-shell (have one unpaired electron). And the energy of NiSubPC with different spin multiplicities (1 and 3) was calculated. The results show that the energy of NiSubPC with spin
Journal Pre-proof multiplicity of 3 is lower than that with spin multiplicity 1 (see Table S12). However, as shown in Table S0, the binding energy of NiSubPC with multiplicity of 1 is lower. Therefore we still chose NisubPC with spin multiplicity of 1 in the main manuscript. For comparisons, the ground- and excited state properties of NisubPC with spin multiplicity of 3 are also given out in SI Tables S0-5 and S7-11 and Figures S5-10. Note that SOMO (singly occupied molecular orbital) may be the better description than HOMO and LUMO for these molecules. However, for consistency, HOMO and LUMO are still used in the rest of this manuscript. To obtain insights into these molecules, natural bond orbital (NBO) analyses
oo
f
were performed with NBO Version 3.1[57] embedded in Gaussian software package. We simulated the UV-Vis spectra of monomer MSubPC based on the excited
pr
state calculations using traditional B3LYP and LRC CAM-B3LYP and LC-ωPBE density functionals, which have been proved to be able to reproduce experimental
e-
electronic absorption spectra.[58] Multiwfn software package was used to generate
Pr
absorption spectra.[59]
Based on the excited states of TDDFT calculation, the wavelength of simulated absorption peaks are given as following:
𝜆1 ∗𝑂𝑆1 +𝜆2 ∗𝑂𝑆2 +⋯+𝜆𝑛 ∗𝑂𝑆𝑛
al
𝜆𝑎𝑣𝑒 =
𝑂𝑆1 +𝑂𝑆2 +⋯+𝑂𝑆𝑛
(3)
rn
where 𝜆𝑛 /OSn is the wavelength/oscillator strength of the nth excited state,
Jo u
respectively; the subscript n is the nth excited states of TDDFT results within the half-width of a absorption peak. In this work, the energy of half-width of absorption peak was set to the default value 0.667 eV.[60] The cone height ‘h’ of MSubPC (as shown in Figure 2), which denotes the nonplanar property of subPC and its derivatives,[61] was computed with the following equation (а, β, θ, a, b are known geometry parameters )
Journal Pre-proof
ℎ12+ℎ22 −𝑐 2
h1=a×sinα; h2=b×sinβ; θ=arccos（
2ℎ1 ℎ2
）; h=h1×sinθ
（4）
oo
f
Figure 2. The cone height of MSubPC. M: metal atom, N: nitrogen atom, h: cone height.
pr
3. Results and discussion
e-
We initially give optimized geometry of MSubPC (M= Fe, Co, Ni, Cu, Zn) in gas phase. Then the ground and excited state properties in condensed phase, i.e. obtained
Pr
with PCM, are presented, since it is close to experimental condition and reality. Then the results of MSubPC monomer are discussed.
al
3.1. Geometry parameters.
rn
Firstly, all geometry optimizations of MSubPC (M= Fe, Co, Ni, Cu, Zn) monomers were run in gas phase. For simplicity and clarity, the geometry parameters
Jo u
including bond length, angles, and cone heights are listed in Supporting Information (SI) Table S1 and Figure S0. We find that all these monomers may be chemically stable according to the optimized results in gas phase. Of course, this may be not enough and synthesis experiments of these monomers are needed for further confirmation. Furthermore, since most of experimental structures are measured in the solid state or solution, we obtain the optimized geometry parameters of MSubPC (M=Fe, Co, Ni, Cu, Zn）monomers with PCM. The geometry parameters are given out in Table 1. The MSubPC molecules are quite different from the reference subPC since the B-Cl fragment is replaced with different metal atoms. However, the results of reference subPC molecule are still able to calibrate how the metal substitutions
Journal Pre-proof influence the geometries since the geometry parameters of subPC molecule have been extensively measured in the solid state.[62] As shown in Table 1 and Figure S0, B3LYP functional slightly overestimates the B-N bond length relative to experimental value of subPC. But, overall, the results match well with experimental data achieved with XRD technique in the solid state.[62] Therefore one can reasonably guess that the optimized geometry of MSubPC series is reliable since DFT calculations have been widely used to study organic metal complexes.[32] Table 1. The optimized geometry parameters of subPC and MSubPC (M= Fe, Co, Ni, Cu, Zn)
M-N2
M-N3
Exp
∠N1-X-N2
1.48
1.48
1.48
1.47
105.5
FeSubPC
1.80
1.80
1.80
N/A
90.0
CoSubPC
1.77
1.85
1.85
N/A
88.9
NiSubPC
1.82
1.73
1.82
N/A
CuSubPC
1.81
1.87
1.87
N/A
ZnSubPC
1.89
1.89
1.89
Cone Exp
Exp Height
105.5
105.2
0.58
0.59
90.1
90.0
N/A
1.02
N/A
88.9
93.4
N/A
1.02
N/A
90.4
90.6
108.5
N/A
0.90
N/A
90.8
96.7
90.8
N/A
1.02
N/A
91.8
91.7
N/A
1.06
N/A
al
91.6
rn
N/A
∠N1-X-N3
105.5
Pr
subPC
∠N2-X-N3
pr
M-N1
e-
System
oo
f
molecules and experimental structure of subPC. Unit: Å (length) and degree (angle).
The results in Table 1 demonstrate that the non-planarity of MSubPC series
Jo u
becomes stronger than subPC regarding the values of cone heights. One can see that the bond length between metal and nitrogen atoms is generally longer than that of boron-nitrogen bond of subPC, and the metal-involved angles in MSubPC are smaller than these in subPC molecule except for NiSubPC. Therefore the cone heights of MSubPC (M=Fe, Co, Ni, Cu, Zn）are much larger than that of subPC. This is reasonable because the radii of these metal atoms are much larger than that of boron atom. In MSubPC (M=Fe, Co, Ni, Cu, Zn）series, the symmetry is quite different. The spin multiplicities of both CoSubPC and CuSubPC are 2, and the others are 1. FeSubPC and ZnSubPC molecules have C3v symmetry. But MSubPC (M=Co, Ni, Cu) does not. The trigonal pyramidal molecular geometry (C3v) is not always consistent with spin multiplicity. This could be attributed to different electron configurations of d
Journal Pre-proof orbitals of metals, as shown in SI Table S2-S3. For example, in CoSubPC, there is a valence bonding between cobalt and one neighboring nitrogen atom; but for FeSubPC, NBO analyses only show that there are only three lone pair electrons on iron atom. FeSubPC and ZnSubPC have almost identical three angles ( ∠ N1-M-N2, ∠ N2-M-N3, and ∠N1-M-N3), just like subPC molecule. In contrast, in MSubPC (M=Co, Ni, Cu), one angle is always larger than other two similar ones and the deviation
is
at
least
4.5
degree.
The
trend
of
these
deviations
is
CoSubPC
oo
f
different electron configurations of d orbital and atomic radii of these metal atoms. We shall talk this later.
pr
Compared to the gas phase geometry, the results show that all bond length
e-
obtained with PCM is slightly shorter. But overall, the deviation is small than 0.2 angstrom.
Pr
3.2.Ground-state electronic structure, spin density, charge distribution, and dipole moment.
al
As shown in Table 2, the results of NBO analyses of these new molecules are
rn
listed. More details of NBO analyses and localized orbital locator (LOL) are available in SI Table S2-S5 and Figure S1, respectively. One can see that the natural charge of
Jo u
all metal atoms is close to 1.0, but their oxidation states should be about 2.0. We can reasonably conclude that the atomic orbitals of these metal2+ atoms, which are involved in the coordination with nitrogen atoms surrounding them, are mainly 3d, 4s, and 4p atomic orbitals. For example, in FeSubPC molecule, the electron configuration of the Fe2+ cation should be 3d6, however, due to electron back-donating of and covalent bonding with surrounding nitrogen atoms, the natural electron configuration of Fe2+ cation becomes 4s(0.19)3d(6.57)4p(0.13). Note that natural atomic charge of zinc in ZnSubPC is the most positive due to its 4s(0.31)3d(9.90)4p(0.36) configuration, whereas nickel atom of NiSubPC has the smallest positive value attributed to its 4s(0.24)3d(8.43)4p(0.31). In addition, the LOL figure demonstrates that the M-N bonding of all MSubPC seems to be more delocalized with respect to subPC.
Journal Pre-proof Table 2. NBO analyses of metal atoms in MSubPC molecules. System
Natural Charge
Natural Electron Configuration
Fe
1.12
[core]4s( 0.19)3d( 6.57)4p( 0.13)
Co
1.13
[core]4s( 0.19)3d( 7.46)4p( 0.22)
Ni
1.03
[core]4s( 0.24)3d( 8.43)4p( 0.31)
Cu
1.18
[core]4s( 0.25)3d( 9.23)4p( 0.34)
Zn
1.43
[core]4s( 0.31)3d( 9.90)4p( 0.36)
f
In Figure 3, we find that the electron density distribution of HOMOs of MSubPC
oo
(M=Fe, Co, Ni, Cu, Zn）are similar to that of the reference subPC molecule. In contrast, the LUMOs of MSubPC are quite different from subPC: the electron density
pr
distribution of LUMOs of MSubPC (M=Fe, Co, Ni) generally is close to metal atoms.
e-
Especially, the electron distribution of LUMOs of Co-SubPC and Ni-SubPC almost
Jo u
rn
al
Pr
locates on metal atom.
Figure 3. The frontier molecular orbitals of subPC and MSubPC (M= Fe, Co, Ni, Cu, Zn) molecules, obtained with B3LYP/6-31G(D)/PCM theory level. Iso-surface value: 0.03 a.u.
Journal Pre-proof Figure 4. The energy of frontier molecular orbitals of subPC and MSubPC (M= Fe, Co, Ni, Cu, Zn) molecules obtained with B3LYP (half-mark for clarity), CAM-B3LYP and LC-ωPBE (with optimized ω). The latter two are corrected with Equation 1 and 2. The color of code: black－CAM-B3LYP, green －LC-ωPBE, and red－B3LYP.
In Figure 4, one can see that the HOMO energy of MSubPC series is higher than that of subPC in all three functionals, except for ZnSubPC. The LUMO (SOMO) energy and energy gap of CuSubPC is noticeably lower than that of subPC and other MSubPCs. The results also indicate that the corrected CAM-B3LYP HOMO/LUMO
oo
f
energies and energy gap (available in SI Table S6) generally are close to B3LYP uncorrected results compared to LC-ωPBE functional, except for NiSubPC. As we
pr
talked in Computational Details, the HOMO/LUMO energy obtained with B3LYP
e-
density functional has no physical meaning since they cannot satisfy Koopman theorem.[8, 63, 64] This is just a coincidence because of error cancelation. The energy
Pr
gaps obtained with LC-ωPBE are generally larger than CAM-B3LYP ones, except for CoSubPC, which can be attributed to different intrinsic LRC DFT kernel. This finding
Jo u
rn
al
is consistent with the previous researches.[42]
Figure 5. The spin density of CoSubPC and CuSubPC molecules obtained with B3LYP/6-31G(D)/PCM theory level. Iso-surface value: 0.03 a.u.
Table 3. Metal or boron atomic Mulliken charge and spin density of subPC and MSubPC, obtained with B3LYP/6-31G(D)/PCM theory level. Spin: spin multiplicity. System (spin)
M or B
Spin density
SubPC (1)
0.52
N/A
Journal Pre-proof FeSubPC (1)
1.10
N/A
CoSubPC (2)
1.05
0.99
NiSubPC (1)
0.90
N/A
CuSubPC (2)
0.95
0.67
ZnSubPC (1)
1.09
N/A
Next, the Mulliken charges of different center (boron and M) atoms of subPC and MSubPC series are presented in Table 3 because the dipole moments of these
f
molecules are based on Mulliken charges, not natural atomic charges. The metal
oo
atoms of MSubPC have much larger values of positive charge than B atom of subPC. The order of positive charges of metal atoms is Ni
pr
also list the data of dipole moments of subPC and MSubPC series in SI Table S7 and
e-
Figure S2. Compared to subPC, all MSubPC molecules have much smaller dipole moments because of the lack of chloride atom. It is not surprised the trend of dipole
Pr
moments is exactly same as that of positive charges of metal atoms of MSubPC, that is, Ni
al
Finally, spin density of CoSubPC and CuSubPC molecules with unpaired
rn
electrons is shown in Figure 5 and Table 3. Unpaired electron of cobalt or copper atom is not localized anymore. And the spin density (0.67) of copper atom is smaller
Jo u
than that (0.99) of cobalt atom, which means the unpaired electron of copper atom delocalizes more than that of cobalt. 3.3.Absorption spectrum.
The simulated absorption spectra of MSubPC monomers and subPC molecule, achieved with LC-ωPBE/6-31G(D)/PCM level, are shown in Figure 6 (for simplicity, see SI Figure S3 and S4 for CAM-B3LYP and B3LYP results) since LC-ωPBE functional is able to reproduce subPC absorption spectrum well.[65, 66] Similar to subPC molecule, all metal-substituted monomers demonstrate strong absorption strength in the visible region. Interestingly, FeSubPC has even a wider absorption range (320-700 nm) than subPC and other MSubPC (see Figure 6 and SI Figure S3-4).
pr
oo
f
Journal Pre-proof
Figure 6. The simulated electronic absorption (ranged from 300 to 800 nm) spectra of subPC and
e-
MSubPC (M= Fe, Co, Ni, Cu, Zn) molecules based on tuned LC-ωPBE/6-31G* with PCM.
Pr
The total oscillator strength and averaged absorption wavelength of MSubPC series and subPC molecule are summarized in Figure 7 (see SI Table S8a-8b for data).
al
It indicates that only FeSubPC has stronger absorption strength than subPC molecule in the visible region in MSubPC series. The trends of wavelength and oscillator
rn
strength of B3LYP and CAM-B3LYP are basically same. The absorption peaks
Jo u
(averaged wavelength) of ZnSubPC and NiSubPC are red-shifted compared to subPC molecule in the results of all three functionals. In addition, we find that the wavelength of absorption peak of CuSubPC, obtained with CAM-B3LYP, is noticeably blue-shifted.
e-
pr
oo
f
Journal Pre-proof
Figure 7. The averaged absorption wavelength and oscillator strength of MSubPC monomers and
Pr
subPC molecule.
In Figure 8, the transition densities of electron-hole plots of the first absorption
al
state of subPC and MSubPC series with strong oscillator strength are drawn. Basically,
rn
the excitations are π to π* transitions of conjugate aromatic rings. However, for FeSubPC and CoSubPC, the d orbitals of metal atoms are partly involved in the
Jo u
excitations. We further make orbital analyses (see SI Table S9 for details). Overall, the orbitals transitions between HOMO-4 to HOMO and LUMO to LUMO+4 are dominant in these excitations.
Figure 8. The electron-hole densities for the transitions of the first bright (oscillator strength >0.1) excited state of subPC and MSubPC (M= Fe, Co, Ni, Cu, Zn) molecules based on LC-ωPBE /6-31G*
Journal Pre-proof with PCM. The color of code: blue-hole, green-electron. Iso-surface value: 0.003 a.u.
4. Conclusions In summary, MSubPC series has been theoretically proved that they may be chemically stable in gas phase and condensed phase. The calculated binding energy of MSubPC confirm that the order of stability is Fe>Cu>Ni>Co>Zn, and they are much less stable than prototype subPC. In addition, the optimized geometry parameters
f
show that these MSubPC molecules are more non-planar than subPC. Compared to
oo
subPC, all MSubPC molecules also have much smaller dipole moments because of the lack of chloride atom. These results imply that MSubPC series may be feasible for
pr
mixing them with donor materials. Furthermore, we find that the wavelength of
e-
absorption peaks of ZnSubPC and NiSubPC are red-shifted compared to subPC molecule in the results of all three functionals, and especially FeSubPC has even
Pr
stronger absorption strength than subPC in the visible region because its excitation involves more orbital transitions and d electrons. The work here shows a new way to
al
design photoelectric materials based on subphthalocyanine with center metal
Jo u
subPC.
rn
substitution. All these findings suggest a new strategy of designing metal-substituted
In the future, we plan to find some superior metals or non-metal atoms since its homologue phthalocyanine has remarkable diversities and the cavity of PC can contain up to seventy different atoms.
Acknowledgements We greatly thank for valuable suggestions from Ms. Xue Chen and Ms. Wenjing Wang. We also appreciate Fundamental Research Funds for the Central Universities (XDJK2016A016, XDJK2016E014, XDJK2017D015, and XDJK2017D019) and Start-up funding from Southwest University (SWU117018). S.Z. also thanks the financial support from the Start-up Funding for Young Faculty of Southwest University. This project is also supported by Program for Innovation Team Building at
Journal Pre-proof Institutions of Higher Education in Chongqing（CXTDX201601011）.
References [1] A.M.A. 0ssko, Phthalocyaninartige Bor-Komplexe, Monatsh. Chem. , 103 (1972) 150-155. [2] C.G. Claessens, D. Gonzalez-Rodriguez, M.S. Rodriguez-Morgade, A. Medina, T. Torres, Subphthalocyanines, subporphyrazines, and subporphyrins: singular nonplanar aromatic systems, Chem Rev, 114 (2014) 2192-2277. [3] Y. Lin, Y. Li, X. Zhan, Small molecule semiconductors for high-efficiency organic photovoltaics, Chem Soc Rev, 41 (2012) 4245-4272. [4] K.A. Mazzio, C.K. Luscombe, The future of organic photovoltaics, Chem Soc Rev, 44 (2015)
f
78-90.
oo
[5] A. Mishra, P. Bauerle, Small molecule organic semiconductors on the move: promises for future solar energy technology, Angew Chem Int Ed Engl, 51 (2012) 2020-2067.
pr
[6] C. Duan, G. Zango, M. Garcia Iglesias, F.J. Colberts, M.M. Wienk, M.V. Martinez-Diaz, R.A. Janssen, T. Torres, The Role of the Axial Substituent in Subphthalocyanine Acceptors for Bulk-Heterojunction Solar Cells, Angew Chem Int Ed Engl, 56 (2017) 148-152.
e-
[7] H. Gommans, T. Aernouts, B. Verreet, P. Heremans, A.s. Medina, C.G. Claessens, T. Torres, Perfluorinated Subphthalocyanine as a New Acceptor Material in a Small-Molecule Bilayer
Pr
Organic Solar Cell, Adv Funct Mater, 19 (2009) 3435-3439. [8] O.V. Gritsenko, Koopmans’ theorem and its density-functional-theory analog assessed in evaluation of the red shift of vertical ionization potential upon complexation, Chem Phys Lett, 691 (2018)
al
178-180.
[9] C.B. Kc, G.N. Lim, F. D'Souza, Tuning Optical and Electron Donor Properties by Peripheral
rn
Thio-Aryl Substitution of Subphthalocyanine: A New Series of Donor-Acceptor Hybrids for Photoinduced Charge Separation, Chemistry, 22 (2016) 13301-13311.
Jo u
[10] H. Lee, S.W. Ahn, S.H. Ryu, B.K. Ryu, M.H. Lee, S.W. Cho, K.E. Smith, T.S. Jones, Interfacial electronic structure of Cl6SubPc non-fullerene acceptors in organic photovoltaics using soft X-ray spectroscopies, Phys Chem Chem Phys, 19 (2017) 31628-31633. [11] J. Guilleme, D. Gonzalez-Rodriguez, T. Torres, Triflate-subphthalocyanines: versatile, reactive intermediates for axial functionalization at the boron atom, Angew Chem Int Ed Engl, 50 (2011) 3506-3509. [12] J. Guilleme, L. Martinez-Fernandez, I. Corral, M. Yanez, D. Gonzalez-Rodriguez, T. Torres, Direct Access to Axially Substituted Subphthalocyanines from Trimethylsilyl-Protected Nucleophiles, Org Lett, 17 (2015) 4722-4725. [13] S. Kalia, A. Mahajan, C.G. Ghansyam, A.K. Debnath, V. Saxsena, D.K. Aswal, R.K. Bedi, Anisotropic charge transport properties in boron sub phthalocyanine chloride thin films, J Appl Phys, 121 (2017) 095501. [14] E. Maligaspe, M.R. Hauwiller, Y.V. Zatsikha, J.A. Hinke, P.V. Solntsev, D.A. Blank, V.N. Nemykin, Redox and photoinduced electron-transfer properties in short distance organoboryl ferrocene-subphthalocyanine dyads, Inorg Chem, 53 (2014) 9336-9347. [15] R. Menting, D.K. Ng, B. Roder, E.A. Ermilov, Sequential energy and charge transfer processes in mixed host-guest complexes of subphthalocyanine, porphyrin and phthalocyanine chromophores,
Journal Pre-proof Phys Chem Chem Phys, 14 (2012) 14573-14584. [16] Z. Wang, X. Fu, Synthesis, Characterization, and Reactivity Studies of Subphthalocyanine Boron Triflate, Organometallics, 36 (2017) 285-290. [17] M.M. Montero-Campillo, A.M. Lamsabhi, O. Mo, M. Yanez, UV/Vis spectra of Subporphyrazines and Subphthalocyanines with Aluminum and Gallium: a Time-Dependent DFT Study, ChemPhyschem, 14 (2013) 915-922. [18] Y. Yang, Metal–ligand coordination in subphthalocyanines and phthalocyanines: DFT, AIM and ELF analyses, Polyhedron, 33 (2012) 310-318. [19] Y.J. Yang, Z.M. Su, Structure, stability, and aromaticity of M-SubPc (M=B, Al, and Ga): Computational study, Int J Quantum Chem, 103 (2005) 54-59. [20] J.H.Y. Daocheng X, Qing Long B, Chuanhui Cheng, Peng X, Lifeng L, Zhaoqi F, Guotong D ＊,
f
Synthesis and Characterization of Subphthalocyanine Copper, Journal of Shanxi University
oo
(Natural Science Edition), (2009) 426-431.
[21] M.M. Montero-Campillo, A.M. Lamsabhi, O. Mo, M. Yanez, Photochemical Behavior of
pr
Beryllium Complexes with Subporphyrazines and Subphthalocyanines, J Phys Chem A, 120 (2016) 4845-4852.
[22] X. Ji, T. Zou, H. Gong, Q. Wu, Z. Qiao, W. Wu, H. Wang, Cobalt phthalocyanine nanowires:
e-
Growth, crystal structure, and optical properties, Cryst Res Techol, 51 (2016) 154-159. [23] S. Kaipova, H. Dinçer, A. Altindal, Synthesis, characterization, conduction, and dielectric
Pr
properties of tetratert-butylsulfanyl substituted phthalocyanines, J Coord Chem, 68 (2014) 717-731.
[24] P. Muthukumar, H.-S. Kim, J.W. Jeong, Y.-A. Son, Synthesis and characterization of tetra
al
phenoxy-substituted halogen-rich metallophthalocyanine derivatives: A study on their LCD color filter requirements, J Mol Struct, 1119 (2016) 325-331.
rn
[25] Z. Wang, R. Wei, X. Liu, Preparation and dielectric properties of copper phthalocyanine/graphene oxide nanohybrids via in situ polymerization, J Mater Sci, 51 (2016) 4682-4690.
Jo u
[26] A. Banerjee, B. Kundu, A.J. Pal, Introducing immobilized metal phthalocyanines as spin-injection and detection layers in organic spin-valves: Spin-tunneling and spin-transport regimes, Org Electron, 41 (2017) 173-178.
[27] M. Yıldırım, O. Köysal, G. Önsal, E. Gümüş, Effect of iron phthalocyanine (FePc) concentration on electrical and dielectric properties of the nematic liquid crystal composites, J Mol Liq, 223 (2016) 868-872. [28] N. Heo, Y. Kim, Y. Jung, S. Cheon, S. Cho, S.W. Cho, S. Park, Y. Yi, K.E. Smith, Interfacial electronic structure of C 60 /ZnPc/AZO on photoemission spectroscopy for organic photovoltaic applications, Chem Phys, 478 (2016) 145-149. [29] M.-S. Liao, S. Scheiner, Electronic structure and bonding in metal phthalocyanines, Metal=Fe, Co, Ni, Cu, Zn, Mg, J Chem Phys, 114 (2001) 9780-9791. [30] Z. Liu, Z.-X. Chen, B. Jin, X. Zhang, Theoretical studies on the structures and vibrational spectra of Ni, Pd, and Pt phthalocyanines, Vib. Spectrosc, 56 (2011) 210-218. [31] Y. Gao, P.V. Solntsev, V.N. Nemykin, Comparative electronic structures and UV-vis spectra of tribenzosubporphyrin,
tribenzomonoazasubporphyrin,
tribenzodiazasubporphyrin,
and
subphthalocyanine: insight from DFT and TDDFT calculations, J Mol Graph Model, 38 (2012) 369-374.
Journal Pre-proof [32] Y.J. Yang, Y.H. Kan, Z.M. Su, L. Zhao, Theoretical study on stability and nonlinear optical properties of novel subphthalocyanine dimer and trimer, J Mol Struc-Theochem, 725 (2005) 127-131. [33] D. Zdravkovski, M.C. Milletti, A comparison of structural and electronic characteristics among subphthalocyanine and phthalocyanine complexes, J Mol Struc-Theochem, 717 (2005) 85-89. [34] L.A. Leal, W.F. da Cunha, L.A. Ribeiro Junior, T.L. Pereira, S.M. Blawid, R.T. de Sousa Junior, D.A. da Silva Filho, Optical and electronic structure description of metal-doped phthalocyanines, J Mol Model, 23 (2017) 172. [35] C. Azarias, M. Pawelek, D. Jacquemin, Structural and Optical Properties of Subporphyrinoids: A TD-DFT Study, J Phys Chem A, 121 (2017) 4306-4317. [36] A. Dreuw, Long-range charge-transfer excited states in time-dependent density functional theory require non-local exchange, J Chem Phys, 119 (2003) 2943-2946.
f
[37] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman, G. Scalmani,
oo
V. Barone, B. Mennucci, G.A. Petersson, H. Nakatsuji, M. Caricato, X.H. Li, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.;
pr
Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A., Jr.; Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.;
e-
Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, N. J.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.;
Pr
Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, Ö.; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J., in, Gaussian Inc., Wallingford CT, 2009.
al
[38] E. Cancès, B. Mennucci, J. Tomasi, A new integral equation formalism for the polarizable continuum model: Theoretical background and applications to isotropic and anisotropic dielectrics,
rn
J Chem Phys, 107 (1997) 3032-3041.
[39] A.W. Lange, J.M. Herbert, A smooth, nonsingular, and faithful discretization scheme for 244111.
Jo u
polarizable continuum models: the switching/Gaussian approach, J Chem Phys, 133 (2010) [40] A.W. Lange, J.M. Herbert, Symmetric versus asymmetric discretization of the integral equations in polarizable continuum solvation models, Chem Phys Lett, 509 (2011) 77-87. [41] S.H. Zheng, M.Y. Xiao, Y.P. Tian, X. Chen, Prediction of the lowest charge-transfer excited-state energy at the donor-acceptor interface in a condensed phase using ground-state DFT calculations with generalized Kohn-Sham functionals, J. Mol. Model., 23 (2017) 235. [42] M.Y. Xiao, Y.P. Tian, S.H. Zheng, An insight into the relationship between morphology and open circuit
voltage/electronic
absorption
spectrum
at
donor-acceptor
interface
in
boron
subphthalocyanine chloride/C70 solar cell: A DFT/TDDFT exploration, Org. Electron., 59 (2018) 279-287. [43] H. Phillips, S. Zheng, A. Hyla, R. Laine, T. Goodson, 3rd, E. Geva, B.D. Dunietz, Ab initio calculation of the electronic absorption of functionalized octahedral silsesquioxanes via time-dependent density functional theory with range-separated hybrid functionals, J Phys Chem A, 116 (2012) 1137-1145. [44] S.H. Zheng, H. Phillips, E. Geva, B.D. Dunietz, Ab Initio Study of the Emissive Charge-Transfer States of Solvated Chromophore-Functionalized Silsesquioxanes, J. Am. Chem. Soc., 134 (2012)
Journal Pre-proof 6944-6947. [45] A.D. Becke, DENSITY-FUNCTIONAL EXCHANGE-ENERGY APPROXIMATION WITH CORRECT ASYMPTOTIC-BEHAVIOR, Phys. Rev. A 38 (1988) 3098-3100. [46] A.D. Becke, Density‐functional thermochemistry. III. The role of exact exchange, J Chem Phys, 98 (1993) 5648-5652. [47] B. Miehlich, A. Savin, H. Stoll, H. Preuss, RESULTS OBTAINED WITH THE CORRELATION-ENERGY DENSITY FUNCTIONALS OF BECKE AND LEE, YANG AND PARR, Chem Phys Lett, 157 (1989) 200-206. [48]
M.E.
El-Khouly,
Electron
transfer
naphthalocyanine-subphthalocyanine
reaction
self-assembled
of
dyad:
light
harvesting
spectroscopic,
zinc
electrochemical,
computational, and photochemical studies, Phys Chem Chem Phys, 12 (2010) 12746-12752. [49] M.E. El-Khouly, D.K. Ju, K.Y. Kay, F. D'Souza, S. Fukuzumi, Supramolecular Tetrad of Porphyrin
Coordinated
to
f
Subphthalocyanine-Triphenylamine-Zinc
Fullerene
as
an
Nonpolar Solvent, Chem-Eur J, 16 (2010) 6193-6202.
oo
"Antenna-Reaction-Center" Mimic: Formation of a Long-Lived Charge-Separated State in
pr
[50] Z.Q. Liu, X.X. Zhang, Y.X. Zhang, J.Z. Jiang, Theoretical investigation of the molecular, electronic structures and vibrational spectra of a series of first transition metal phthalocyanines, S.A.P:M&B.S, 67 (2007) 1232-1246.
e-
[51] G.A. Petersson, M.A. Al‐Laham, A complete basis set model chemistry. II. Open‐shell systems and the total energies of the first‐row atoms, J Chem Phys, 94 (1991) 6081-6090.
Pr
[52] G.A. Petersson, A. Bennett, T.G. Tensfeldt, M.A. Al‐Laham, W.A. Shirley, J. Mantzaris, A complete basis set model chemistry. I. The total energies of closed‐shell atoms and hydrides of the first‐row elements, J Chem Phys, 89 (1988) 2193-2218.
al
[53] H. Phillips, S.H. Zheng, E. Geva, B. Dunietz, Predictive computational methods for charge transfer in organic optoelectronic materials, Amer. Chemical Soc., 246 (2013).
rn
[54] T. Yanai, D.P. Tew, N.C. Handy, A new hybrid exchange–correlation functional using the Coulomb-attenuating method (CAM-B3LYP), Chem Phys Lett, 393 (2004) 51-57.
Jo u
[55] T.M. Henderson, A.F. Izmaylov, G. Scalmani, G.E. Scuseria, Can short-range hybrids describe long-range-dependent properties?, J Chem Phys, 131 (2009) 044108. [56] H. Phillips, Z. Zheng, E. Geva, B.D. Dunietz, Orbital gap predictions for rational design of organic photovoltaic materials, Org Electron, 15 (2014) 1509-1520. [57] A.E.R. E. D. Glendening, J. E. Carpenter, and F. Weinhold, NBO Version 3.1. [58] X. Chen, W.L. Chen, S.H. Zheng, Reproduction of the UV-vis spectra of boron subphthalocyanine chloride in different solvents using time-dependent generalized Kohn–Sham density functionals with first solvation shell, J Porphyr Phthalocya, 22 (2018) 670-678. [59] T. Lu, F. Chen, Multiwfn: a multifunctional wavefunction analyzer, J Comput Chem, 33 (2012) 580-592. [60] S. Peng, S. Zheng, A computational investigation on core‐expanded subphthalocyanines, Int. J. Quantum Chem, (2019) e25942. [61] K. Kasuga, T. Idehara, M. Handa, Y. Ueda, T. Fujiwara, K. Isa, Structure and some properties of (alkoxo)(subphthalocyaninato)boron(III), Bull. Chem. Soc. Jpn., 69 (1996) 2559-2563. [62]
H.
Kietaibl,
CRYSTAL
AND
MOLECULAR-STRUCTURE
OF
A
NEW
PHTHALOCYANINE-LIKE BORON COMPLEX, Monatsh. Chem., 105 (1974) 405-418. [63] A. Dreuw, M. Head-Gordon, Failure of time-dependent density functional theory for long-range
Journal Pre-proof charge-transfer
excited
states:
The
zincbacteriochlorin-bacterlochlorin
and
bacteriochlorophyll-spheroidene complexes, J. Am. Chem. Soc., 126 (2004) 4007-4016. [64] S. Hirata, C.G. Zhan, E. Apra, T.L. Windus, D.A. Dixon, A new, self-contained asymptotic correction scheme to exchange-correlation potentials for time-dependent density functional theory, J. Phys. Chem. A, 107 (2003) 10154-10158. [65] Y.D. Zhao, J.J. Fu, H.B. Li, H. Dong, Y. Liao, Photoinduced charge transfer processes of zinc porphyrin derivatives for dye-sensitized solar cells, Chem. Res. Chinese U., 29 (2013) 974-981. [66] X. Chen, S. Zheng, Inferring the molecular arrangements of boron subphthalocyanine chloride in thin film from a DFT/TDDFT study of molecular clusters and experimental electronic absorption spectra, Org Electron, 62 (2018) 667-675.
f
Author Contribution
oo
Conceptualization：Shaohui Zheng
pr
Data curation：Wenlan Chen; Suoping Peng
Pr
Funding acquisition： Shaohui Zheng
e-
Formal analysis： Shaohui Zheng; Wenlan Chen; Suoping Peng
Investigation：Shaohui Zheng; Wenlan Chen
al
Methodology：Shaohui Zheng; Wenlan Chen
rn
Project administration：Shaohui Zheng
Jo u
Resources：Shaohui Zheng Software：Shaohui Zheng
Supervision：Shaohui Zheng Validation：Shaohui Zheng Visualization：Wenlan Chen; Suoping Peng Roles/Writing - original draft：Wenlan Chen; Writing - review & editing：Shaohui Zheng
Journal Pre-proof Declaration of Competing Interest There are no conflicts to declare.
Jo u
Highlights
rn
al
Pr
e-
pr
oo
f
Graphical abstract
By modeling MSubPC through center metal substitutions (metal= Fe, Co, Ni, Cu, and Zn) of subPC, the calculated results show that MSubPC series may be chemically stable, and the predicted order of the stability of MSubPC is Fe>Cu>Ni>Co>Zn. Also, this new series of MSubPC molecules all becomes more non-planar and has much smaller dipole moments than subPC, which imply that they may be feasible for blend with organic acceptors. The HOMO-LUMO energy gaps of MSubPC (M=Co, Ni, Cu) are smaller than that of subPC. Furthermore, FeSubPC has noticeably stronger absorption strength than subPC because its excitation involves more orbital transitions and d electrons.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8