Geometric Shape Regulation and Noncovalent Synthesis of One

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Geometric Shape Regulation and Non-Covalent Synthesis of One-Dimensional Organic Luminescent Nano/Micro-Materials Xiaoxian Song, Zuolun Zhang, Shou-Feng Zhang, Jinbei Wei, Kaiqi Ye, Yu Liu, Todd B Marder, and Yue Wang J. Phys. Chem. Lett., Just Accepted Manuscript • DOI: 10.1021/acs.jpclett.7b01643 • Publication Date (Web): 24 Jul 2017 Downloaded from http://pubs.acs.org on July 26, 2017

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The Journal of Physical Chemistry Letters

Geometric Shape Regulation and Non-Covalent Synthesis of One-Dimensional Organic Luminescent Nano/Micro-Materials Xiaoxian Song,† Zuolun Zhang,† Shoufeng Zhang,† Jinbei Wei,† Kaiqi Ye,*,† Yu Liu,† Todd B. Marder,‡ and Yue Wang*,† † State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China ‡ Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany

Corresponding Authors [email protected] (Y. W.) [email protected] (K. Y.)

ACS Paragon Plus Environment

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ABSTRACT. Non-covalent synthesis of one-dimensional (1D) organic nano/micro-materials with controllable geometric shapes or morphologies and special luminescent/electronic properties is one of the greatest challenges in modern chemistry and material science. Control of non-covalent interactions is fundamental for realizing desired 1D structures and crucial for understanding the functions of these interactions. Here, a series of thiophene-fused phenazines composed of a halogen-substituted π-conjugated plate and a pair of flexible side chains is presented, which displays halogen-dependent 1D self-assemblies. Luminescent 1D twisted wires, straight rods and zigzag wires, respectively, can be generated in sequence when the halogen atoms are varied from the lightest F to the heaviest I. It was demonstrated that halogendependent anisotropic non-covalent interactions and mirror-symmetrical crystallization dominated the 1D-assembly behaviors of this class of molecules. The methodology developed in this study provides a potential strategy for constructing 1D organic materials with unique optoelectronic functions.

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Over the past decade, organic one-dimensional (1D) materials based on π-conjugated molecules have attracted a vast amount of attention in both basic and applied research due to their potential to serve as active materials in high-performance optoelectronic devices, such as lighting-emitting diodes,1,2 field-effect transistors,3,4 lasers,5 etc.6,7 The development of organic 1D materials will open the door to a new generation of optoelectronic technology. The noncovalent synthesis or supramolecular self-assembly of organic 1D nano/micro-materials based on molecular building blocks with optoelectronic activities is one of the greatest challenges in modern chemistry and material science.8 It is well known that sophisticated organic nano/microarchitectures composed of luminescent semiconducting components are crucial for achieving desired properties. Significant progress has been made in the assembly of linear and smoothly bent/curved 1D organic materials, such as straight, bent, twisted and helical wires.9-22 However, non-covalent self-assemblies of 1D or quasi-1D organic nano/micro-materials with other welldefined geometric shapes or morphologies, such as zigzag, rectangle, diamond and so on, remain unresolved issues. The limited geometric shapes of 1D organic materials restrict their applications in future organic devices. The organic optoelectronic interconnects and integrated circuits, which provide a high efficiency or special signal-input/output properties, require 1D materials with uniform and controllable geometric structure. Therefore, it is urgently desired to promote the growth of 1D organic materials along a programmable pathway. For 1D organic nano/micro-materials, the appropriate geometric architectures and specific properties are two indispensable characteristics for the fabrication of high-performance organic optoelectronic devices. The morphologies and properties of organic nano/micro-materials are significantly dependent on the nature of intermolecular non-covalent interactions.23-27 Therefore, to achieve desired/unprecedented geometric structures and properties, the precise regulation of


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non-covalent interactions within organic nano/micro-materials is the fundamental issue. Further development of 1D organic wires with optimized performance requires deep understanding of the dependence of supramolecular structures on non-covalent interactions. Intermolecular non-covalent interactions (such as π···π stacking, hydrogen bonding, halogen bonding, C–H···π and van der Waals interactions) in organic supramolecular systems are very sensitive to the geometry, conformation, rigidity, functional-group arrangement, π-conjugation size and electron donor-acceptor (D-A) characteristic of the molecular building block.28,29 On the other hand, most of the organic supramolecular systems are constructed based on the cooperation of various non-covalent interactions.30,31 In this context, the investigation of systematic design, synthesis and assembly of organic building blocks featuring optoelectronic activity and functional groups that can potentially be involved in non-covalent interactions benefit the establishment of efficient approaches for constructing 1D organic nano/micro-materials with unique properties. In this contribution, we report the supramolecular 1D self-assembly properties of a class of thiophene-fused phenazines (Scheme 1a). The construction strategy of these molecular building blocks towards unique 1D architectures with remarkable functions is based on the following considerations: (i) a T-shaped coil-plate-coil structure composed of a π-conjugated plate and two flexible side chains may promote the anisotropic assembly of building blocks; (ii) the D-A character of the π-conjugated plate with electron-deficient phenazine fused by electron-rich thiophene rings may provide desirable optoelectronic functions; (iii) the large π-conjugated plate modified with alkyl chains and sulfur and halogen atoms potentially affords intermolecular van der Waals, C–H···π, π···π, S···S and halogen-bonding interactions which are expected driving forces for supramolecular self-assemblies; and (iv) the abundant molecular building blocks with


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various halogen atoms and other possible groups provide an opportunity for in-depth understanding of the mechanism of supramolecular assembly.

Scheme 1. Molecular structures and their corresponding abbreviations (a) and halogen dependent intermolecular interactions and molecular packing modes (b). The dithienophenazine (DTP) derivatives FDTP-C6, ClDTP-C6, BrDTP-C6 and IDTP-C6 were synthesized (see Supporting Information) in high yields by the condensation reaction of 2,7-dihexylbenzo[2,1-b:3,4-b']dithiophene-4,5-dione

and

the

halogen-substituted

o-

phenylenediamine. The self-assembly behaviors of XDTP-C6 were firstly studied employing a solvent-evaporation procedure. A solution of XDTP-C6 (0.25 mg/mL) in the chloroform/ethyl acetate (V:V = 1:2) mixed solvent was applied dropwise onto a clean silicon substrate located in a glass container with a cover. After natural evaporation of the solvent under ambient


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temperature and atmosphere, 1D nano/micro-wires were generated on the substrate (Figure 1a-f) as confirmed by the field emission scanning electron microscopy (FESEM). Remarkably, the geometric shapes of the wires exhibited the nature of halogen dependence. FDTP-C6 molecules assembled into dispersed twisted wires with a length of more than several hundred of micrometers (Figure 1a). The twisted wires showed green-yellow emission under fluorescence microscopy (Figure 1g), and their widths and twist pitches were around 0.25 and 0.90 µm, respectively. The twisting feature of the wires allowed us to identify their thickness of about 80 nm based on the high-magnification SEM images (Figure 1b). In contrast, the ClDTP-C6-based 1D nano/micro-structures showed versatile morphologies (Figure 1c,d), with the straight rods, zigzag wires and twisted wires simultaneously generated on the same substrate. These results revealed the apparently stronger helical-assembly ability of FDTP-C6 than ClDTP-C6. It was demonstrated that some achiral organic molecules composed of conjugated plane and flexible alky chains often exhibit helical self-assembly property and this behavior was attributed to mutual competition of different non-covalent intermolecular interactions, which can induce orthogonal axial directions.32,33 Unlike the separated twisted wires of FDTP-C6, the twisted wires of ClDTP-C6 formed bundles by entanglement of slender fibers. Intriguingly, well-dispersed 1D zigzag wires were successfully achieved within the whole growth region on the substrate when BrDTP-C6 was employed as the building block. These zigzag wires possessed a relatively uniform appearance with lengths of several tens micrometers and widths of 100-200 nm (Figure 1e). Similar to BrDTP-C6, IDTP-C6 also showed the zigzagassembly behavior (Figure 1f). The zigzag wires of ClDTP-C6, BrDTP-C6 and IDTP-C6 consisted of clear zigzag segments and corners, which were periodically repeated along the 1D growth pathway of a wire. Although the lengths of the zigzag segments varied to a large extent,


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it was easily observed that the zigzag angles were generally fixed, which were 105° for ClDTPC6, 106° for BrDTP-C6 and 113° for IDTP-C6. The fluorescence images of the wires of ClDTPC6, BrDTP-C6 and IDTP-C6 are shown in Figure 1h-j.

Figure 1. Morphologies of self-assembled 1D materials obtained by solvent evaporation on silicon substrates. FESEM images of helical fibers (a) and magnified helical fibers (b) from FDTP-C6, entangled twisted fibers (c) and short zigzag pieces (d) from ClDTP-C6, long zigzags from BrDTP-C6 (e) and IDTP-C6 (f). Fluorescence microscopy images of the assembled structures of FDTP-C6 (g), ClDTP-C6 (h), BrDTP-C6 (i) and IDTP-C6 (j). Fluorescence microscopy images of a single zigzag wire of BrDTP-C6 (k) and IDTP-C6 (l). The influence of solution concentrations on material morphologies was also studied. Upon decreasing the concentration of the ethyl acetate solution of FDTP-C6 from 1.00 to 0.01 mg/mL, the morphologies of prepared 1D nano/micro-materials varied gradually from straight wire to curly wire and then to twisted wire (Figure S1). This result suggests that fast nucleation of


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FDTP-C6 molecules leads to a linear structure and slow nucleation results in a twisted architecture. It is worth noting that if the mixed chloroform/ethyl acetate (V:V = 1:2) solvent was employed, only twisted wires were generated upon varying the concentration of the FDTP-C6 solution. For solutions of BrDTP-C6 or IDTP-C6 in the chloroform/ethyl acetate mixed solvent, four concentrations (1.00, 0.50, 0.25 and 0.10 mg/mL) were employed to prepare 1D materials, and zigzag morphologies were observed (Figures S2 and S3) for all of the solutions suggesting that the formation of zigzag wires is not sensitive to the initial concentrations under a fixed solvent media. The nature of solvent has dramatic influence on the self-assembly behaviors of XDTP-C6 molecules when solvent-evaporation procedure is employed. Generally, pure good solvents such as chloroform, tetrahydrofuran and so on can not result in the formations of twisted wires for FDTP-C6 and zigzag structure for BrDTP-C6 or IDTP-C6. However, in the mixture solutions composed of good solvent (chloroform, ethyl acetate and tetrahydrofuran) and poor one (methanol, ethanol, propanol and isopropanol) FDTP-C6 molecules easily assemble into twisted wires (Figure S4) and BrDTP-C6 or IDTP-C6 ones likely aggregate into zigzag structures (Figure S5). Furthermore, under ambient temperature and atmosphere diverse solvent medias have different evaporation speed, which should have an effect on the self-assembly behaviors. Besides the substrate-supported 1D self-assemblies based on the solvent-evaporation process, the substrate-free self-assemblies of XDTP-C6 in solution were also investigated. A chloroform solution of XDTP-C6 (0.5 mg/mL, 2 mL) was added into a test tube and then carefully layered by the poor solvent, ethanol (5 mL). Slow solvent diffusion resulted in crystallization at the interfacial region of the two solvents. Ten minutes after the addition of ethanol, a small amount of solution in the interfacial region was removed and dropped immediately onto a carbon-coated copper grid for the transmission electron microscopy (TEM) characterization. It is worth noting


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that ten-minutes of solvent diffusion does not lead to any solid visible to naked eye in the interfacial region. TEM images (Figure S6) confirmed that 1D nano-structures with morphologies similar to those of the samples prepared by solvent evaporation were generated in the interfacial region. However, these 1D structures are much thinner. Significant numbers of 1D structures with widths of ca. 50 nm were observed for the samples prepared by short-time (< 30 min) solvent diffusion. Upon extending the diffusion time, the size of the 1D structures increased (Figure S7). When the diffusion time was longer than 24 h, 1D micro-wires that can be observed by the naked eye were generated in the interfacial region. Thus, the variable morphologies of XDTP-C6-based 1D nano/micro-structures can be ascribed to the nature of XDTP-C6, i.e. the self-assembly of XDTP-C6 and the intermolecular non-covalent interactions directing it are very sensitive to the halogen atoms on the molecular skeleton. To understand the features of non-covalent interactions in XDTP-C6-based 1D materials, needle-like single crystals were prepared by the vapor-diffusion method (see Supporting Information) and analyzed by X-ray diffraction. The twisted wires of FDTP-C6 were not perfectly crystalline, and attempts to obtain their crystal structure were unsuccessful. Therefore, the structure of straight, needle-like crystals of FDTP-C6 is employed as a reference to disclose the possible supramolecular structures of the twisted wires. Although the needle-like and the twisted samples belong to different solid phases, their intermolecular-interaction characteristics may be comparable. The single-crystal structure of the needle-like sample may provide a possible explanation on the relationship between non-covalent interactions and morphology characteristics of the twisted 1D wires. In the needle-like crystal of FDTP-C6, there are abundant intermolecular interactions such as π···π stacking, C–H···F hydrogen bonds and S···S contacts (Figure S8a,b). Along the crystallographic b axis, the FDTP-C6 molecules adopt a wave-like


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arrangement due to intermolecular C–H···F hydrogen-bonding and S···S interactions (Figure S8c). Such an arrangement suggests the possibility of FDTP-C6 to aggregate into twisted/helical structures. However, in twisted/helical FDTP-C6 wires the precise intermolecular interaction feature remains unknown and for FDTP-C6 based twisted/helical nano/micro structure different supramolecualr interactions may be adopted. In the needle-like crystals of ClDTP-C6, BrDTP-C6 and IDTP-C6, the molecular packing modes are almost identical (Figures 2 and S9-S10). The molecules form square-like tetramers in the (1 3 2) plane for ClDTP-C6 and BrDTP-C6, and in the (1 3 2) plane for IDTP-C6, and the perfectly ordered array of tetramers results in a molecular sheet. In the tetramers, the four molecules are linked together by intermolecular C–H···Cl hydrogen bonds for ClDTP-C6, C– H···Br hydrogen bonds and Br···Br interactions for BrDTP-C6, and I···I interactions for IDTPC6. Upon increasing the weight of halogen atoms, the halogen-bonding interactions become more and more important for the construction of the crystal planes. The slipped π···π stacking interactions between the π-conjugated plates of adjacent sheets result in the formation of 1D crystals.


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Figure 2. Supramolecular structures of the needle-like crystals. (a) BrDTP-C6 and (b) IDTP-C6: view perpendicular to (1 0 0) plane (left); top view of a molecular sheet (middle) and square-like tetramer (right) with short intermolecular contacts highlighted with light blue lines. To gain insight into the mechanism of the unique 1D-assembly properties of XDTP-C6, theoretical calculations on the crystallization morphologies were performed with the Materials Studio package based on the crystallographic data of the needle-like single crystals. The attachment energies (AE) (Tables S1-S4) for different crystal planes were obtained. For the crystal of FDTP-C6, the (1 1 1) and (1 0 0) planes have obviously larger AE, suggesting that the crystallographic a axis is the superior direction of crystal growth (Figure S11). A similar character of AE distributions is obtained for the needle-like crystals of ClDTP-C6, BrDTP-C6 and IDTP-C6. For these crystals, the (0 1 0) and (0 0 1) planes have much smaller AE compared with the (1 k l) (k =1, 0, 1 and 3; l =2, 1, 0, 1 and 2) planes, suggesting that the a axis is the dominant direction of growth upon crystallization. The theoretically predicted growth morphologies of the needle-like crystals of ClDTP-C6, BrDTP-C6 and IDTP-C6 are illustrated in Figures 3 and S12. The theoretical calculations provided fundamental support for the thermodynamic stability of 1D crystal structures of ClDTP-C6, BrDTP-C6 and IDTP-C6. Intriguingly, in the 1D crystal of BrDTP-C6, the dihedral angle between the (0 1 0) plane with small AE and the (1 3 2) plane with large AE is 53.0°, which is equal to half of the turning angle (106.0°) observed in the zigzag nano-crystals of BrDTP-C6 (Figure 3c). Therefore, the formation mechanism of the zigzag crystals of BrDTP-C6 can be assigned to the symmetrical crystallization with the (1 3 2) plane as a mirror. During the generation of a zigzag wire, the straight 1D crystal of BrDTP-C6 successfully grew via layer-by-layer stacking of (1 3 2) planes. In a zigzag wire, a number of (1 3 2) planes were adopted as the shared lattice plane for mirror-


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symmetrically connecting two straight 1D crystals. For an ideal zigzag structure, the joints between two straight 1D crystals should be seamless. The extremely large AE difference between the (1 3 2) and (0 1 0) planes provides a driving force for the generation of a unique zigzag 1D organic nano-structure. For the zigzag crystals of ClDTP-C6 and IDTP-C6, a crystallographic character identical to that of the zigzag crystals of BrDTP-C6 was observed (Figures 3d and S12). For the 1D crystal of ClDTP-C6, the AE differences between (0 0 1)/(0 1 0) and (1 0 0)/ (1 3 2) planes are not large enough, and therefore the tendency of ClDTP-C6 to form a zigzag structure is significantly weaker compared with those of BrDTP-C6 and IDTP-C6. In addition, the zigzag wires can be regarded as the products of crystal twining. Above experimental and theoretical studies revealed that halogen substitution has dramatic influence on intermolecular interactions and consequently on the self-assembled microstructures, which is summarized in Scheme 1b. The theoretical studies provides useful information about thermodynamic stability of 1D crystal structures of XDTP-C6. Moreover, the following experimental results also demonstrated that this assembly process should be thermodynamic control: (i) the 1D crystals used for single crystal studies were generated based on long time (3-5 days) crystallizations; (ii) with their morphologies and emission properties maintained, these helical fibers, zigzag 1D materials can be stored for over one year in a glass container under an ambient atmosphere, which implies the thermodynamic stability of these materials. The calculated total crystal energies of BrDTP-C6 and IDTP-C6 1D crystals are obviously larger than that of FDTP-C6 crystal (Table S5) suggesting that BrDTP-C6 and IDTP-C6 based 1D crystals can more easily generate under different concentrations. Therefore, the morphology of BrDTPC6 and IDTP-C6 assemblies are not sensitive to their initial concentrations.


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Figure 3. 1D-assembly mechanism and mirror-symmetrical crystallization feature. Theoretically predicted growth morphologies of needle-like crystals of BrDTP-C6 (a) and IDTP-C6 (b), as well as schematic presentations of the formation of zigzag structures (fragments of TEM images) for BrDTP-C6 (c) and IDTP-C6 (d). The powder X-ray diffraction (PXRD) patterns of 1D self-assembled samples of XDTP-C6 (twisted wires for FDTP-C6; mixture of twisted wires, straight rods and zigzag wires for ClDTPC6; zigzag wires for BrDTP-C6 and IDTP-C6) were recorded (Figure S13). The PXRD pattern of the twisted wires of FDTP-C6 is obviously different from that simulated based on the singlecrystal X-ray diffraction data of the needle-like crystals of FDTP-C6, indicating that the twisted wires and needle-like crystals belong to different solid phases. For the other three 1D selfassembled samples, their PXRD patterns match the simulated patterns of corresponding needlelike samples well. Therefore, for ClDTP-C6, BrDTP-C6 and IDTP-C6, the zigzag and needlelike samples are attributed to the same crystalline phase. This result is reasonable as the zigzag wire is the integration of a number of straight rods. Due to a high aspect ratio between length and width, almost all of the 1D nano/micro-crystals are parallel to the substrate. For the 1D nano/micro-structures of ClDTP-C6, BrDTP-C6 and IDTP-C6, their anisotropic orientation


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feature is sufficiently disclosed by the PXRD patterns. The strong diffraction peaks corresponding to (0 0 1) and (0 1 0) planes suggest that these lattice planes are relatively parallel to the substrate. As expected, for the PXRD patterns of ClDTP-C6, BrDTP-C6 and IDTP-C6, the strongest peak is indexed to (0 0 1) plane. Therefore, the top surface of the 1D structures should be the (0 0 1) plane, which is consistent with the result of theoretical calculations. For the ClDTP-C6 nano-sample, the twisted component is likely in a phase with low crystallinity. Therefore, there is no signal for the twisted component in the PXRD pattern. Interestingly, slow evaporation of chloroform solutions of ClDTP-C6, BrDTP-C6 and IDTPC6 led to large orange crystals with a bar shape for ClDTP-C6 and a block shape for BrDTP-C6 and IDTP-C6. These crystals displayed red emission under UV light (Figure 4). Single-crystal Xray diffraction demonstrated that all of these crystals possess layer-type arrangements of molecules, and the packing modes of molecular layers are different from those adopted in corresponding needle-like crystals with green-yellow emission (Figures 4a,b and S14-S15). The bar-/block-shaped crystals of ClDTP-C6, BrDTP-C6 and IDTP-C6 adopt different molecularlayer arrangements, and they possess additional C–H···Br, C–H···I and S···S interactions compared with the needle-like crystals. The richer intermolecular interactions often induce a red shift of emission. Theoretical calculations revealed that the bar-shaped crystals of ClDTP-C6 have a relatively strong 1D-growth tendency, while the block-shaped crystals of BrDTP-C6 and IDTP-C6 have a very weak 1D-crystallization character (Tables S6-S8 and Figures S16-S18). The calculated total crystal energies (Table S5) revealed that the bar-/block-shaped crystals are slightly more stable phases compared with their corresponding need-like crystals. In Figure 4a, crystal twinning is presented. Based on crystal structure investigation this phenomenon is attributed to the symmetrical crystallization with the (4 2 2) plane, which has with large AE


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(Table S7), as a mirror. When the melted samples of ClDTP-C6, BrDTP-C6 and IDTP-C6 were cooled, slow (0.5 K min−1) and rapid (10 K min−1) cooling resulted in red emissive bar-/blockshaped crystals and green-yellow emissive needle-like crystals, respectively (Figure 5). As revealed by the PXRD patterns (Figure S19), for each compound, the sample obtained from slow cooling is identical in crystalline phase to the crystals generated by slow evaporation of chloroform solutions, while the sample obtained from rapid cooling forms the same crystalline phase as the needle-like crystals generated by slow vapor diffusion. The fact that rapid cooling leads to straight 1D crystals for ClDTP-C6, BrDTP-C6 and IDTP-C6 suggests the intrinsic 1Dself-assembly nature of these compounds. It is rational that slow cooling processes result in the formation of more thermodynamically stable phases, while rapid cooling generated 1D crystalline phases.

Figure 4. Crystal morphologies and supramolecular structures. Fluorescence microscopy images (top) and molecular packing diagrams (bottom) of the large orange crystals of BrDTP-C6 (a) and IDTP-C6 (b).


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Figure 5. Polymorphism of ClDTP-C6, BrDTP-C6 and IDTP-C6. Fluorescence microscopy images showing the crystallization of melted samples: I, cooling at 10 K min-1; II, cooling at 0.5 K min-1. Intriguingly, the zigzag wires of BrDTP-C6 and IDTP-C6 exhibit a unique luminescent phenomenon, showing green yellow-lighting spots at all zigzag corners (Figure 1k,l). All of the reported organic materials with active waveguides are generally straight/bent nano/micro-wires that can only produce two bright spots at the two termini of the wire.34-36 The special lightwaveguide property of the zigzag nano/micro-structures of BrDTP-C6 and IDTP-C6 may have potential applications in various optoelectronic nano/micro-devices, in which multiple bright spots are needed. The zigzag morphologies can be prepared on the substrates of silica, glass and indium tin oxide (Figure S20), suggesting that these zigzag wires may be used to fabricate nano/micro-devices on these substrates. Although some inorganic and organometallic zigzag wires formed through covalent bonds are known,37-39 pure organic zigzag wires based on noncovalent interactions have, to the best of our knowledge, never been reported. In summary, a series of T-shaped coil-plate-coil molecules, XDTP-C6, composed of a halogen-substituted π-conjugated plate and a pair of flexible side chains has been synthesized.


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This class of luminescent organic molecules exhibits unique halogen-dependent 1D selfassembly property. By varying the halogen atoms, luminescent 1D wires with twisted, straight and zigzag morphologies have been obtained. Detailed single-crystal X-ray analyses and theoretical calculations demonstrated that halogen-dependent anisotropic non-covalent interactions dominate the 1D-assembly behaviors and crystal structures of XDTP-C6. For BrDTP-C6 and IDTP-C6, with heavy halogen atoms and an appropriate molecular geometry, Br···Br or I···I interactions result in the formation of planar, square-like molecular tetramers, which pack together through π···π stacking interactions to form the 1D structure. The remarkable AE difference of various crystal planes is the driving force for the 1D growth of XDTP-C6. The unprecedented 1D zigzag self-assemblies of organic molecules BrDTP-C6 and IDTP-C6 is attributed to the mirror-symmetrical crystallization based on (1 3 2) and (1 3 2 ) planes, respectively. We have thus developed an efficient strategy, i.e. alternation of halogen substituents, for regulating geometric shapes of 1D organic nano/micro-materials. ASSOCIATED CONTENT Supporting Information Supporting Information Available: Additional details of the synthesis, single-crystal growth, assembly experiments of 1D materials, Supplementary Figures and Tables, crystallo-graphic data (CIF files) of single crystals and other information.

AUTHOR INFORMATION Corresponding Authors *E-mail: [email protected] (Y. W.)


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*E-mail: [email protected] (K. Y.) Notes The authors declare no competing financial interests. ACKNOWLEDGMENT This work was supported by the National Natural Science Foundation of China (91333201), National Basic Research Program of China (2015CB655003). We thank the staffs from BL17B beam line of National Facility for Protein Science in Shanghai (NFPS) at Shanghai Synchrotron Radiation Facility, for assistance during data collection. REFERENCES (1) Tang, C. W.; VanSlyke, S. Organic Electroluminescent Diodes. App. Phys. Lett. 1987, 51, 913-915. (2) Baldo, M. A.; Thompson, M. E.; Forrest, S. R. High-Efficiency Fluorescent Organic LightEmitting Devices Using a Phosphorescent Sensitizer. Nature 2000, 403, 750-753. (3) Wang, C.; Dong, H.; Hu, W.; Liu, Y.; Zhu, D. Semiconducting π-Conjugated Systems in Field-Effect Transistors: a Material Odyssey of Organic Electronics. Chem. Rev. 2012, 112, 2208−2267. (4) Usta, H.; Facchetti, A.; Marks, T. J. n-Channel Semiconductor Materials Design for Organic Complementary Circuits. Acc. Chem. Res. 2011, 44, 501−510. (5) Wang, X.; Li, H.; Wu, Y.; Xu, Z.; Fu, H. Tunable Morphology of the Self-Assembled Organic Microcrystals for the Efficient Laser Optical Resonator by Molecular Modulation. J. Am. Chem. Soc. 2014, 136, 16602−16608. (6) Clark, J.; Lanzani, G. Organic Photonics for Communications. Nat. Photonics 2010, 4, 438−446.


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Geometric Shape Regulation and Noncovalent Synthesis of One

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