Polymeric Fused-Ring Type Iron Phthalocyanine Nanosheet and Its

Apr 2, 2012 - Polymeric Fused-Ring Type Iron Phthalocyanine Nanosheet and Its ... anisotropy comes from unquenched in-plane orbital moments for...
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Polymeric Fused-Ring Type Iron Phthalocyanine Nanosheet and Its Derivative Ribbons and Tubes Long-Hua Li,† Jun-Qian Li,‡ and Li-Ming Wu*,† †

State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, People’s Republic of China ‡ Department of Chemistry, Fuzhou University, Fuzhou, Fujian 350002, People’s Republic of China S Supporting Information *

ABSTRACT: On the basis of density functional theory calculations, we study the electronic and magnetic properties of an iron phthalocyanine (FePc) nanosheet (FePcNST) and its derivatives, nanoribbons (FePcNRs) and nanotubes (FePcNTs). The GGA+U +SOC calculations reveal that the interesting in-plane magnetic anisotropy comes from unquenched in-plane orbital moments for FePcNST. The calculations indicate that the most stable antiferromagnetic (AFM) ordering for FePcNRs is G-type AFM, which is independent of the ribbon width. In addition, FePcNTs with radii larger than 10 Å are thermodynamically and thermally stable and can be rolled up from the FePcNST with only several millielectronvolts energy cost. Interestingly, the most stable AFM types of FePcNTs highly depend on the number of Fe ions (odd or even) on the circumference. These results may shed useful light on further experimental and theoretical studies on the organometallic nanosheet and its one-dimensional derivatives.

1. INTRODUCTION Recently, stacked FePc films have been extensively investigated both theoretically and experimentally to reveal their electronic and magnetic properties,1−4 self-assembly patterns,5 as well as the interactions between the FePc molecule and the substrate.6 The self-assembly process is governed by the intermolecular interactions, which include the van der Waals forces among the individual FePc molecules and the molecule−substrate interactions; therefore, we consider that two important issues should be pointed out: (1) The well-ordered FePc molecule film is difficult to be synthesized; for example, at least four different types of FePc film have been reported, e.g., c(10 × 4) superstructure,5 p(10 × 4) superstructure,5 (5 × 3) chainlike single layer,6 and film with textured columnar grains.3 (2) The electronic and magnetic properties of the stacked FePc films may depend on the different organization patterns of the molecule as well as the different substrate utilized;5,7 thus, the measured properties may not be intrinsic. Therefore, it is necessary to characterize the intrinsic properties on a monolayer film, in which the FePc monomers are connected by covalent bonds and the substrate-mediated interactions are negligible as compared with the intramolecular interactions. The first FePc polymer was synthesized in 1973;8 however, few reports on polymeric FePc have been published since then, and especially the studies on low-dimensional polymeric FePc film or sheet are extremely rare. Up to date, three types of polymeric MPc (M = Fe, Co, Ni, etc.) or Pc are known (Supporting Information, Figure S1), which are hereafter referred to as fused-ring type (FR),9 direct-ring-joint ,10 and organic-object-joint type,11,12 respectively. However, to synthe© 2012 American Chemical Society

size a periodic 2D organometallic polymer remains a great challenge.13 A single layer of FR polymeric FePc sheet on a metal surface and a thin insulating film was synthesized in 2010;14 however, the properties of such a sheet are not yet well characterized. On the other hand, how to construct a 1D tubular/ribbon polymeric MPc or M porphyrin (MP) differing from the extensively studied graphene nanoribbons and carbon nanotubes is of great interest. Although many organometallic nanowires15−18 have been predicted, the relevant reports on 1D polymeric MPc or MP are rare. Gomez-Romero9 indicated with the aid of the tight-binding method in 1987 that the FR CuPc polymer nanoribbon was highly conductive. Cho19 showed on the basis of the density functional theory (DFT) calculations in 2011 that the 1D ferromagnetic Cr porphyrin (CrP) array possesses spin filtering effect, and recently, Zhou and Sun20 studied the magnetic coupling of the 2D sheets Pc containing different transition metals. In this paper, we systematically study the electronic and magnetic properties of the novel FR FePc nanosheet (FePcNST) and its derivative nanoribbons (FePcNRs) and nanotubes (FePcNTs).

2. COMPUTATIONAL DETAILS All calculations were performed by the Vienna ab initio simulation package (VASP).21 The plane wave basis with the frozen-core projector augmented wave (PAW) potential was used.22,23 The generalized gradient approximation (GGA) of Received: September 20, 2011 Revised: April 2, 2012 Published: April 2, 2012 9235

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Perdew−Burke−Ernzerhorf24 and a plane wave cutoff energy of 400 eV were set. To evaluate the magnetic anisotropy and the orbital moment, the spin−orbit coupling (SOC) was employed. Because of the strong correlation effect of Fe(II) 3d6, the onsite repulsion U method was considered in both structure optimization and band structure calculations. A correlation energy U = 4.0 eV and an exchange energy J = 1.0 eV for Fe were used as in previous works. As Figure 1a shows, a 25 × 25 × 11 Å3 tetragonal box was taken to isolate a single molecule of FePcMol. The Gaussian

3. RESULTS AND DISCUSSION 3.1. Electronic and Magnetic Properties of FePcNST and FePcMol. Utilizing the previously well-tested20 U (4 eV) and J (1 eV), the structures of FePcNST (Figure 1b) and the isolated FePcMol (Figure 1a) are fully optimized. The lattice parameters of FePcNST are 10.68 Å, which are in good agreement with the available experimental data 11.5 ± 1 Å10 and the calculated value 10.70 Å.20 For the isolated FePcMol, the Fe−N bond length of 1.949 Å is in excellent agreement with the experimental length, 1.927 Å,25 and previous calculation result 1.958 Å.4 The spin states of Fe 3d6 in FePcMol and FePcNST were then studied. The SCF calculations with the magnetic moment of Fe constrained to high spin (HS: initial set, 4 μB; end of SCF calculation: 3.8 μB), low spin (LS: initial set, 0 μB; end of SCF calculation, 0 μB), and intermediate spin (IS: initial set, 2 μB; end of SCF calculation, 1.96 μB), together with the nonconstrained calculation, were performed. The total energy of the NSP state is assumed to be zero, and then the relative energies of HS, LS, IS, and nonconstrained SCF for FePcNST are 1860.09, 0.07, −767.05, and −766.87 meV, respectively, which indicate that FePcNST has IS ground state. Our studies also indicate that FePcMol always converges to the IS state no matter what kind of magnetic moment constraint is applied on Fe; this is consistent with the experimental observation.26−29 The most interesting magnetic phenomenon of stacked αFePc film3 and α-FePc crystal30 is the in-plane magnetic anisotropy. However, its origin is not well understood. In this section, we investigated the magnetic anisotropy origin of FePcMol and FePcNST based on GGA+U+SOC calculations. To obtain the energy anisotropy and orbital moment, structurerelevant symmetry and time-reversal symmetry are broken. In the calculation of the orbital moment and relative energy, the spin quantization direction (or magnetic field) was set to be along the [100], [010], and [001] direction, as summarized in Table 1. The calculated average orbital moment 0.17 μB is

Figure 1. Optimized structures of the FePc single molecule (FePcMol) and FePc 2D sheet (FePcNST).

smearing method was set with a broadening width of 0.1 eV. A total of three k points were set in the induced Brillouin zone (IBZ) in the self-consistent field (SCF) calculation. The unit cell of the monolayer FePcNST is shown in Figure 1b, and the x- and y-axes were parallel to the FePc plane. The 11 Å distance along the z-axis was tested to be long enough to separate the nearest-neighboring FePc sheets. 11 × 11 × 1 kpoints were set for the SCF calculation, and 19 × 19 × 1 kpoints were set for the magnetic properties calculation. Four types of FePcNRs with different width (Figure 3a−d) and four types of FePcNTs with different radii (Figure 6a−d) are shown. The extending direction was set along the xdirection. The distance between two next-nearest ribbons or tubes along the y- and z-direction was fixed around 12 Å. Nineteen k-points were set at the extending direction, and only 1 k-point was used at the other two directions for the density of states calculation. The formation energy (Ef) of FePcNST and FePcNTs was defined as Ef = (Etot − aEH − bEC − cEN − dEFe)/(a + b + c + d), where Etot, EH, EC, EN, and EFe were the total energy of FePcNST or FePcNTs, energy of H in the H2 molecule, energy of C in cubic carbon solid (Fd3̅m), energy of N in the N2 molecule, and energy of Fe in the cubic Fe metal (Im3̅m), respectively. Symbols of a, b, c, and d were the number of H, C, N, and Fe atoms involved in the unit cell of FePcNST or FePcNTs. According to this definition, the energetically favorable structure should have a large negative Ef. The strain energy (Es) of FePcNTs was also calculated according to Es = tot tot tot (Etot tube − xEsheet)/natoms, where Etube and Esheet were the total energies per unit cell of the nanotube or nanosheet; x represented the number of FePc sheet units; and natoms was the total number of atoms in a nanotube, respectively. The Es was defined as the energy cost to wrap up a FePc sheet into a tube. Therefore, it is easy to roll the FePc tubes with low Es from the corresponding FePc sheets. A quantum molecular dynamics (QMD) simulation in the canonical ensemble using a Nosé thermostat was carried out for FePcNTs at 500 K. The time step is set at 1.0 fs for a total 5 ps simulation.

Table 1. Comparison of the Orbital Moments and Energy Anisotropy for FePcMol and FePcNSTa system FePcMol FePcNST

ML(x) = ML(y) b

0.227; 0.53 ; 0.15 0.053

E(x) = E(y)

ML(z) c

0.119; 0.29 0.0

b

−0.64 −0.56

a

ML(x), ML(y), and ML(z) are the orbital moments (μB) of the Fe ion along [100], [010], and [001] spin quantizations, respectively. E(x) and E(y) are the relative energy along x and y under the assumption of E(z) = 0 meV. bExperimental values from ref 3. cAverage orbital moment calculated by the FP-LAPW method from ref 30.

consistent with the previous DFT result of 0.15 μB,31 and the results of FePcMol are slightly smaller than the magnetic circular dichroism (XMCD) experimental values.3 Such a discrepancy partly comes from the fact that the XMCD measurement was measured on a FePc textured film deposited on a gold-plated sapphire substrate, in which the FePc− substrate surface interactions likely enhanced the orbital moment.32 Thus, the slight underestimate of our calculations on the orbital moment is reasonable. The calculated orbital moments of FePcMol are larger than those of FePcNST, especially along the (001) direction (z-axis), but FePcNST has a remarkable magnetic moment anisotropy in the xy plane (Table 1). To further understand the magnetic anisotropy of IS Fe(II) in FePcNST, the energy dependence upon the spin 9236

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Figure 2. Energy and orbital moment dependence on the Fe spin direction of FePcNST. φ is the angle between the spin quantization and the z-axis.

Figure 3. Unit cells of four FePc nanoribbon (FePcNRs) models with different widths. (a) FePcNR-1; (b) FePcNR-2; (c) FePcNR-3; and (d) FePcNR-4.

direction was calculated. The spin angle φ (angle between zaxis) varies from 0 to 180° at intervals of 10°. For each φ, the angle α (angle beween the x-axis on the xy-plane) which varies from 0 to 180° at an interval of 10° is also tested; however, energies are all the same no matter which α on the xy-plane, so we just use α = 0° to show the anisotropy dependence on φ. As plotted in Figure 2a, FePcNST prefers spin quantization paralleling to the xy-plane, and the energy minimum occurs at 90°; i.e., the spin lies in the xy-plane. The energy minimum on the xy-plane is 0.56 meV/Fe lower than that along the z-axis. The same situation exists to the orbital moments (Figure 2b). The orbital moment increases as the spin quantization approaches 90° and reaches its maximum on the xy-plane, whereas the orbital moment is almost zero along the z-axis. We will examine in the following section the origin of magnetic anisotropy in FePcNST or FePcMol. As we know, the magnetic moment contains two components, spin and orbital moments. For 3d metals, the orbital moment is usually very small and can be neglected. However, in some cases, the orbital moments are found to be large, for example, Co on the Cu(100) surface32 and Ni in NiO.33 Similarly, our GGA+U +SOC calculations indicate that the orbital moment of the Fe ion in FePcNST is not fully quenched. As the spin moment is determined by the charge density difference between spin-up and -down states, it is almost a constant in all spin quantization directions, e.g., 1.86 for FePcNST. However, the orbital moment depends on the spin quantization and reaches to the maximum on the xy-plane. Considering the D4h symmetry of Fe(II) 3d6 electronic configuration of FePc, the spin−orbit mixing should occur between the half-occupied eg (dxz, dyz) and unoccupied a1g (dz2) states;3 that is to say, the half-occupied eg

(dxz, dyz) should be split by SOC. Such a split results in the contributions of dxz and dyz to the SOC state, which depends on the direction of the magnetic field; i.e., the orbital moment contribution to the total energy is depending on the spin quantization direction. Therefore, the lowest energy should occur along the direction in which the spin and orbital moments contribute mostly to the SOC state. We, therefore, conclude that the large in-plane orbital moments give rise to the in-plane magnetic anisotropy of both FePcNST and FePcMol. 3.2. Electronic Properties of FePcNRs. Inspired by the attractive electronic properties of graphene nanoribbons (GNRs) for nanoelectronics, the electronic and magnetic properties of four FePcNRs labeled as FePcNR-1 to FePcNR-4 were studied. These four fully relaxed FePcNRs have different width from 14.9 to 36.1 Å, as indicated in Figure 3. We, first, examined the favorite magnetic structures of those nanoribbons. To study the magnetic structures, all nanoribbon structures were doubled along the x-axis, i.e., [100] direction. We considered three types of antiferromagnetic (A-AFM, CAFM, and G-AFM) states of FePcNR-2 and FePcNR-4. Because of the geometrical restriction, i.e., the number of Fe ions are incommensurate with spin orders, only one AFM state (named AF) is applied to FePcNR-1, and two AFM states (CAFM, G-AFM) are available for FePcNR-3. All of the AFM structures can be found in the Supporting Information, Figure S2. The energy difference between FM and AFMs is shown in Table 2. The so-called A-, C-, and G-AFM orderings correspond to the alternating ferromagnetic layers coupled antiferromagnetically along the [001] direction, [100] direction, and AFM coupling for all the nearest Fe atoms, 9237

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Table 2. Relative Energies and Sketch Maps of Different Antiferromagnetic Structures of FePcNRs and FePcNTsa

a

Assuming the energy of ferromagnetic states is zero (in units of meV/Fe). Two Ising spins (up and down) are represented by red and blue balls, respectively.

respectively.34 We found that all AFM structures are more stable than FM structures. The ground states of the FePcNR-2, FePcNR-3, and FePcNR-4 are found to be G-type AFM, and the previous works20 also indicated the G-AFM ordering of FePcNST. Then we looked into their electronic structures of the most stable AFM ground states. The densities of states (DOS) of four AFM structuresAF-type AFM of FePcNR-1 and G-type AFM of the other three FePcNRsare plotted in Figure 4. The broad-to-narrow shape of DOS bands indicates the band degeneracy with the decrease of the ribbon width, or it is a result of the quantum size confinement effect. The details of Fe 3d m-decomposed DOS seem to be intricate, in particular, for Fe-dxy (dark green line) and Fe-dz2 (light green line). Most of Fe-dxy are located around −0.5 eV in the valence bands of FePcNR-2 and FePcNR-3, only few Fe-dz2 are found around −6.0 eV; FePcNR-4 lies on the opposite side showing Fe-dz2 around −0.5 eV and Fe-dxy around −6.0 eV; even for FePcNR-1, Fe-dz2 and Fe-dxy are absent in the whole energy rang from −7 to 7 eV. The other three Fe 3d states (d(x2−y2), dyz, and dxz) show some common characters for all FePcNRs: (1) dyz and dxz are no longer fully degenerate as observed in the FePcNST20 because of the breaking of D4h symmetry of those AFM structures; (2) d(x2−y2) states almost appear in the range of −6 to −4 eV; (3) the highest occupied states are entirely from Pc, and the lowest unoccupied states consist of dxy and Pc. Besides, all stable AFM structures are small bandgap semiconductors. Their HOMO and LUMO levels are also plotted in Figure 5a for comparison. The

notations HOMO and LUMO here are defined, respectively, as the highest valence band and the lowest conduction band at Γ. As show in Figure 5a, the gaps between HOMO and LUMO are 0.65, 0.44, 0.35, and 0.28 eV from FePcNR-1 to FePcNR-4, respectively. Although their bandgaps depend inversely on the ribbon width, a saturated value seems to exist, i.e., the bandgap of FePcNST (0.24 eV20). Moreover, the bandgap mainly depends on the HOMO level because the slope of HOMO is larger than that of LUMO. To display HOMO and LUMO directly, charge densities of HOMO and LUMO are also calculated. The HOMO consists of the antibonding interactions between C pz and C pz, while the LUMO comes from the bonding interactions of C pz−C pz, C pz−N pz, and Fe dxz (or dyz)−N pz (see Figure S3, Supporting Information). 3.3. Structural, Electronic, and Magnetic Properties of FePcNTs. Four types of FePc nanotubes were constructed via rolling FePcNST, as shown in Figure 6. The unit cell of the thinnest FePcNT contains three FePc monomers, and the widest one contains six FePc monomers and a total of 198 ions. All these structures were fully optimized to be around 5.1, 6.6, 8.2, and 10.1 Å in radii for FePcNT-1, FePcNT-2, FePcNT-3, and FePcNT-4, respectively. The nearest Fe−Fe distance is 10.599 Å along the x-direction (defined as the tube-axis direction), which is 0.049 Å smaller than that in FePcNST, whereas the nearest Fe−Fe distance on the yz-plane (the tube circumferential direction) increases with the increase of the tubular radius, which is about 8.69, 9.46, 9.86, and 10.12 Å in FePcNT-1, FePcNT-2, FePcNT-3, and FePcNT-4, respectively. 9238

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Figure 4. Density of states of FePcNRs ((a) FePcNR-1; (b) FePcNR-2; (c) FePcNR-3; and (d) FePcNR-4) with the most energetically favored antiferromagnetic structures. y-axis labels DOS of Fe 3d; black, total; red, partial. Fermi energy is set to 0. Black curve, spin-up channel; red curve, spin-down channel.

Figure 5. HOMO and LUMO levels of (a) FePcNRs and (b) FePc nanotubes (FePcNTs) with the most energetically favored AFM structures. Green and blue dots are the HOMO and LUMO levels of FM FePcNTs, respectively. The metallic FM states of FePcNT-2 and FePcNT-4 have actually no HOMO and LUMO.

Detailed structure information was listed in the attached cif files (Supporting Information). The stability of FePcNTs and the possibility that these tubes could be rolled from the corresponding FePc nanosheet were evaluated by the formation energy and strain energy. As shown in Figure 7a, the thermodynamic stability of FePcNT increases with the increase of the tubular radius, and the fitting curves indicate that the FePcNTs wider than FePcNT-4 (i.e., tubular radius >10 Å) will have low formation energy (Ef < −1 meV) and strain energy (Es < 9 meV); that is to say, these nanotubes should be stable and can be rolled up easily from the 2D nanosheet with only several millielectronvolts energy cost. The quantum molecular dynamics calculation was carried out at 500 K to further examine the thermal stability of FePcNT-4. No sign of structure disruption was observed, except that the shape tends to become oval (Figure 7b). Although FePc nanotubes

have not been observed experimentally, our calculations indicate it is highly possible that FePc nanotubes can be prepared under appropriate experimental conditions. We explored the magnetic orderings of four FePcNTs as described in FePcNRs. The relative energies of different AFM structures and their sketches can be seen in Table 2; a more detailed structure chart can be seen in Figure S4 (Supporting Information). These data pointed out three interested features: (1) AFM structures of the nanotube with an even number of Fe ions (even-FePcNT), i.e., FePcNT-2 and FePcNT-4, are not always more stable than FM structures. Only G-AFM ordering is slightly more stable by 0.58 and 0.99 meV/Fe for FePcNT-2 and FePcNT-4, respectively. (2) C-type and AF-type AFM orderings of nanotubes with odd Fe ions (odd-FePcNT), i.e., FePcNT-1 and FePcNT-3, are both more stable than FM orderings, and the AF structure (very close to G-AFM 9239

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Figure 6. Achieving structures of FePcNTs with circumference confined by a different number of FePc monomers. (a) FePcNT-1; (b) FePcNT-2; (c) FePcNT-3; and (d) FePcNT-4. Figure 7. (a) Dependence of the formation energy (Ef) and strain energy (Es) on the number of FePc monomers per unit cell of FePcNTs. (b) Side and top view of the structure of FePcNT-4 in the end of 5 ps quantum MD simulation at 500 K. The cell edge is not shown.

ordering) is energetically favored over the C-AFM by 0.36 and 0.78 meV/Fe for FePcNT-1 and FePcNT-3, respectively. (3) All AFM structures of FePcNTs are less stable than the corresponding FePcNRs. However, larger FePcNT-4 is more stable than smaller FePcNT-2, and FePcNT-3 is more stable than FePcNT-1. Therefore, the AFM structure of FePcNTs with larger radius is likely to be more energetically favored (Table 2). Particularly, FM interactions are not favorable along the tube-axis (i.e., x-axis) and the circumferential direction (or the (001) direction for FePcNRs), and this is the main driving force that gives rise to G-AFM or the most stable AFM structure of FePcNTs and FePcNRs. As odd-FePcNTs and even-FePcNTs are different AFM structures, their electronic structures seem to give some different information. However, we do not find any significant information to explain the effect of the number of Fe (odd or even) from the densities of states of the stable AFM structure. Therefore, electronic structures of FePcNT-3 and FePcNT-4 are shown in Figure 8 as examples. Other electronic structures are shown in Figure S5 (Supporting Information). The total DOS and band structures are similar except that the bandgap of FePcNT-3 is larger than that of FePcNT-4 by 0.2 eV, and the isolated sharp partial DOS of Fe 3d indicates a weak interaction between Fe ions, which may due to the large distances (>10.0 Å) between them. The great DOS difference between two nanotubes may be the valence bands of dxz, dyz, dxy, and dz2. For example, dxz is found mainly around −0.5 and −2.6 eV for FePcNT-3 and FePcNT-4, respectively; for FePcNT-3, dxy is observed mainly at about −3.0 eV, and for FePcNT-4, it is at −1.8 eV. Besides, according to the calculations, FM structures of even-FePcNTs are metallic, and odd-FePcNTs are semiconductor (Figures 5b and 5S, Supporting Information).

4. CONCLUSION The structure of the polymeric fused-ring type FePc nanosheet (FePcNST) as well as its graphene-nanoribbon-like and carbonnanotube-like derivatives, FePc nanoribbons (FePcNRs) and FePc nanotubes (FePcNTs), were constructed and fully optimized with the aid of DFT calculations. Interestingly, FePcNST shows partially quenched orbital moments and strong in-plane magnetic anisotropy tendency, which is likely because the in-plane easy axes orbital moments are larger than the out-of-plane ones. Our calculations indicate that the energetically favored magnetic structures of FePcNRs exhibit antiferromagnetic interaction between adjacent Fe ions, which agree with the previous reported G-AFM structure of FePcNST. In addition, FePcNTs with tubular radii larger than 10 Å, i.e., wider than FePcNT-4, are both thermodynamically and thermally stable and are highly possible to be prepared under suitable conditions. Finally, it is very interesting to note that the magnetic behaviors of odd-FePcNTs are different from the even-FePcNTs; that is, odd-FePcNTs prefer AFM structures (C-AFM and AF) to FM, while for even-FePcNTs, only G-type AFM is more stable than FM structures. However, no significant differences of electronic structures are found among the stable AFM structures of odd-FePcNTs and evenFePcNTs except the different HOMO−LUMO gaps. Further studies on big radius FePcNTs may be expected to establish the relationship between electronic properties and magnetic structures of FePcNTs. We hope our results will be able to 9240

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Figure 8. Density of states and band structures of AF states of FePcNT-3 and G-type AFM states of FePcNT-4. y-axis labels DOS of Fe 3d: black, total; red, partial. Fermi energy is set to 0. Black curve: spin-up channel of DOS. Red curve: spin-down channel. (4) Brena, B.; Puglia, C.; de Simone, M.; Coreno, M.; Tarafder, K.; Feyer, V.; Banerjee, R.; Gothelid, E.; Sanyal, B.; Oppeneer, P. M.; et al. J. Chem. Phys. 2011, 134, 074312. (5) Casarin, M.; Di Marino, M.; Forrer, D.; Sambi, M.; Sedona, F.; Tondello, E.; Vittadini, A.; Barone, V.; Pavone, M. J. Phys. Chem. C 2010, 114, 2144−2153. (6) Gargiani, P.; Angelucci, M.; Mariani, C.; Betti, M. G. Phys. Rev. B 2010, 81, 085412. (7) Ozaki, H.; Harada, Y. J. Am. Chem. Soc. 1987, 109, 949−950. (8) Shormano, Lp; Koifman, O. I.; Berezin, B. D. Vysokomol. Soedin., Ser. B 1973, 15, 910−913. (9) Gomezromero, P.; Lee, Y. S.; Kertesz, M. Inorg. Chem. 1988, 27, 3672−3675. (10) Achar, B. N.; Lokesh, K. S. J. Organomet. Chem. 2004, 689, 2601−2605. (11) Snow, A. W.; Griffith, J. R.; Marullo, N. P. Macromolecules 1984, 17, 1614−1624. (12) Spitler, E. L.; Dichtel, W. R. Nat. Chem. 2010, 2, 672−677. (13) Sakamoto, J.; van Heijst, J.; Lukin, O.; Schlüter, A. D. Angew. Chem., Int. Ed. 2009, 48, 1030−1069. (14) Abel, M.; Clair, S.; Ourdjini, O.; Mossoyan, M.; Porte, L. J. Am. Chem. Soc. 2011, 133, 1203−1205. (15) Maslyuk, V. V.; Bagrets, A.; Meded, V.; Arnold, A.; Evers, F.; Brandbyge, M.; Bredow, T.; Mertig, I. Phys. Rev. Lett. 2006, 97, 097201. (16) Wang, L.; Cai, Z.; Wang, J.; Lu, J.; Luo, G.; Lai, L.; Zhou, J.; Qin, R.; Gao, Z.; Yu, D.; Li, G.; Mei, W. N.; et al. Nano Lett. 2008, 8, 3640−3644. (17) Zhou, L.; Yang, S.-W.; Ng, M.-F.; Sullivan, M. B.; Tan; Shen, L. J. Am. Chem. Soc. 2008, 130, 4023−4027. (18) Wu, X.; Zeng, X. C. J. Am. Chem. Soc. 2009, 131, 14246−14248. (19) Cho, W. J.; Cho, Y.; Min, S. K.; Kim, W. Y.; Kim, K. S. J. Am. Chem. Soc. 2011, 133, 9364−9369. (20) Zhou, J.; Sun, Q. J. Am. Chem. Soc. 2011, 133, 15113−15119. (21) Kresse, G.; Furthmuller, J. Phys. Rev. B 1996, 54, 11169−11186. (22) Kresse, G.; Joubert, D. Phys. Rev. B 1999, 59, 1758−1775. (23) Blochl, P. E. Phys. Rev. B 1994, 50, 17953−17979.

inspire further experimental and theoretical studies on the organometallic nanosheet, nanoribbons, and nanotubes.

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ASSOCIATED CONTENT

S Supporting Information *

Schematic representation of different polymerization types of Mpc or Pc monomer; the antiferromagnetic structures of FePcNRs; charge density of HOMO and LUMO for FePcNRs; antiferromagnetic spin arrangements of FePcNTs; density of states and band structures of FM and AFM structures for FePcNT-1 to FePcNT-4. The structure (cif file) data of four FePcNTs are available. This material is available free of charge via the Internet at http://pubs.acs.org.

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AUTHOR INFORMATION

Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This research was supported by the National Natural Science Foundation of China under projects (20973175) and 973 Program (2010CB933501).

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