Additive-free Morphology Control of Organic Polyhedral Molecular

47 mins ago - The role of anti-solvent molecular geometry on the determination of the final molecular crystals morphology formed by the reverse anti-s...
0 downloads 0 Views 2MB Size
Download PDF
Communication Cite This: Cryst. Growth Des. XXXX, XXX, XXX−XXX

pubs.acs.org/crystal

Additive-Free Morphology Control of Organic Polyhedral Molecular Crystals by the Antisolvent Molecular Geometry: From Rod, Disk, to Cube Yohwan Park,†,‡,# Jin Young Koo,†,‡,# and Hee Cheul Choi*,†,‡ †

Crystal Growth & Design Downloaded from pubs.acs.org by KAOHSIUNG MEDICAL UNIV on 11/09/18. For personal use only.

Center for Artificial Low Dimensional Electronic Systems (CALDES), Institute for Basic Science (IBS), Pohang, 37673, Republic of Korea ‡ Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea S Supporting Information *

ABSTRACT: The role of antisolvent molecular geometry on the determination of the final molecular crystals morphology formed by the reverse antisolvent crystallization (r-ASC) process has been unveiled. Herein, we newly report that the rod-, disk-, and cube-shaped tetra(4-aminophenyl)porphyrin molecular crystals were selectively obtained by employing o-, m-, and p-xylene as an antisolvent during r-ASC process with ethanol employed as a good solvent. The X-ray diffraction results of the crystals provide a clear indication about the correlation between the solute−solvent interactions and the resulting crystal morphologies. The results show that the geometry of xylene has a pivotal effect on the crystal growth direction and morphologies, especially for polyhedrons. This finding would provide opportunities not only for realization of quite rare organic polyhedral crystals but also for in-depth studies about the fundamental crystallization process.

T

he morphology-controlled growth of inorganic1,2 and organic3,4 crystals is an important research subject, which therefore has been studied over the past decades as the morphology of a crystal frequently influences its properties, and eventually on usage in various applications, such as optics,5,6 electronics,7 and catalysis.8−10 In particular, the growth of polyhedral crystals has been explored with significant interest not only due to the emergence of new or enhanced properties from specific crystal facets, but also due to the opportunity for fundamental studies about the crystallization mechanism.11−13 To grow polyhedral crystals, it is critical to control nucleation and growth kinetics. For example, inorganic polyhedral crystals have been synthesized by the colloid, sol, and polyol process,14−16 in which the specific facet growth is controlled by supplying nonsolvent chemical additives. On the other hand, organic polyhedral molecular crystals that are synthesized by molecular self-assembly are rarely reported because weak intermolecular interactions such as van der Waals force, π−π interactions, and hydrogen bonding are easily disturbed by the external factors. The alternative approach to overcome the limitation of organic polyhedral molecular crystal growth is to control the supersaturation environment during the crystal growth step. Surfactants are well-known to induce an abnormal local supersaturation environment that can interrupt the growth of certain crystal planes. Therefore, polyhedral organic crystals with a desired structure can be achieved by using proper surfactants.17−20 However, the efficient adjustment of the local supersaturation environment without any nonsolvent chemical additives for the synthesis of © XXXX American Chemical Society

pure organic molecular crystal growth still remains as a challenge. In this regard, we previously reported the synthesis of welldefined metal containing porphyrin cube crystals by the reverse antisolvent crystallization (r-ASC) method without any special nonsolvent chemical additives involved (Scheme 1a).21 In general, molecular crystallization can be affected by the interactions of solvent−solute and solvent−solvent. Distinctively, depending on the degree and kinds of solvent−solute interaction, the solvent may participate in the crystallization process of the solute or may act simply like a surfactant to induce preferential growth of crystals into a specific direction.22,23 Our previous work elucidated that solvents, especially antisolvents, could play a critical role in determining the crystal growth kinetics by altering the crystallization environment; thus, we motivated the in-depth study of the critical role of antisolvent. However, the metal containing porphyrin in our previous work21 is not appropriate for such studies, as it is difficult to show various morphology control through solvent−solute interactions because it has strong metal−ligand interactions. Therefore, we chose metal-free tetra(4-aminophenyl) porphyrin (TAPP) molecules to elucidate the effect of antisolvent geometry on the morphology of resulting molecular crystals. Interestingly, the TAPP molecular crystals exhibit a clear morphology change form rod, disk, to Received: August 27, 2018 Revised: October 19, 2018 Published: November 7, 2018 A

DOI: 10.1021/acs.cgd.8b01294 Cryst. Growth Des. XXXX, XXX, XXX−XXX

Crystal Growth & Design

Communication

Scheme 1. (a) Reverse Anti-Solvent Crystallization (r-ASC) Process and (b) Morphology of TAPP Crystals Directed by Xylene Molecular Geometry

Figure 1. Scanning electron microscopy (SEM) images of TAPProd, TAPPdisk, and TAPPcube using o-, m-, and p-xylene by r-ASC process and general ASC process. By r-ASC method, the morphology of TAPP crystals are controlled from rod, disk, and cube, but by general ASC method, the morphology of TAPP crystals are obtained only as rod.

patterns showed high crystallinity with different orientations according to the morphologies (Figure S3). To further confirm the importance of the addition order of antisolvent, TAPP molecules were attempted to crystallize under the reverse condition as well, i.e., by the general antisolvent crystallization (ASC) method (Figure S4). When the good solvent (ethanol) was added first, and then antisolvent (xylene) was followed later in the vial containing TAPP powder, only TAPProd crystals were uniformly formed regardless of the geometry of antisolvent (xylene) (Figure 1b). Also, the importance of solvent addition order was proved by using mixed solvent, not separate addition (Figure S5). This result indicates the importance of the solvent addition order, which may provide a critical change in the local supersaturation environment that will eventually influence the nucleation and crystal growth steps, although the bulk environment, such as binary solvent volume ratio and concentration, is still the same. Although there have been several reports dealing with the different crystal growth depending on the geometry of the solvent molecules,24,25 no in-depth understanding about the correlation of the interactions of solvent and solute in each crystal with respect to crystal morphology is available. To elucidate the effect of molecular geometry on morphological control of TAPP crystals, we measured sXRD that provides a clear insight for the correlation of solvent−solute interactions and crystallization pathway. The single crystal X-ray structural analysis of TAPProd (Triclinic, P1) obtained from the o-xylene/ethanol system showed a stacking structure of one-dimensional undulating chains: Two of the four aminophenyl groups in TAPP, located diagonally, form a weak hydrogen bond interaction with a neighboring aminophenyl group, while the other group forms hydrogen bonds with ethanol. Moreover, several ethanol molecules locate in the pore or near the center of the porphyrin ring (Figure 2a and b). In contrast, crystals obtained from m- and p-xylene/ethanol system show completely different network systems. The TAPPdisk (Monoclinic, C2/c) has a long-range 2D layered structure along the ac plane and the 2D layer stacks parallel to the b axis forming a 1D channel

cube with different crystal structures depending on the geometries of the involved antisolvent molecules (Scheme 1b). From the viewpoint of the necessity of various modulations of solvent−solute interactions, TAPP molecule is a good candidate because its highly conjugated system provides multiintermolecular interactions that could result in the growth of multidimensional crystalline structures. Moreover, it still provides an opportunity to interrupt such interactions by small molecules including antisolvents. As shown in Scheme 1, a series of TAPP single crystals could be obtained in different morphologies by the r-ASC method depending on the geometry of the antisolvent. For the r-ASC method, ethanol and xylene were used as good and antisolvents, respectively, and in order to reveal the geometry effect of antisolvent on the crystallization, three different xylene solvents (ortho-, meta-, para-) were used. TAPP powder (1 mg, TCI Chemical, >98%) was first mixed in 0.60 mL of o- (Sigma-Aldrich, 98%), m- (Alfa Aesar, 99%) and p-xylene (Sigma-Aldrich, >99.0%) by ultrasonication for 90 s, and 0.20 mL of ethanol (Sigma-Aldrich, ≥ 99.5%) was added without filtration process. Upon the addition of ethanol, the solution color immediately changed from light purple to dark brown in 10 s because the solubility of TAPP molecules dramatically increased upon the addition of ethanol that dissolves TAPP molecules well and that is mixed with xylene. The reaction mixture was kept at room temperature for 1 h, resulting in well-defined crystal precipitates within 1 h (Figure S1). The resulting TAPP crystals were examined by scanning electron microscopy (SEM), powder X-ray diffraction (pXRD), and single crystal X-ray diffraction (sXRD). The SEM images clearly showed the different TAPP crystal morphologies depending on the geometry of the antisolvent. The rod (TAPProd), disk (TAPPdisk), and cube (TAPPcube) -shaped crystals were obtained from o-, m-, and p-xylene, with the sizes of 50−100 μm, 5−8 μm, and 3−5 μm, respectively (Figures 1 and S2). The corresponding XRD patterns of TAPP crystals were recorded at room temperature using a synchrotron X-ray source. All of the obtained diffraction B

DOI: 10.1021/acs.cgd.8b01294 Cryst. Growth Des. XXXX, XXX, XXX−XXX

Crystal Growth & Design

Communication

Figure 2. TAPP crystal packing structure of (a,b) TAPProd, (c,d) TAPPdisk, and (e,f) TAPPcube obtained by single crystal X-ray diffraction. TAPProd obtained by the r-ASC process in o-xylene/ethanol contains ethanol molecules bonded with TAPP molecules by forming 1D undulating chain. However, TAPPdisk and TAPPcube obtained by r-ASC process in m-xylene/ethanol and p-xylene/ethanol, respectively, contain xylene molecules directly by forming 2D structure. Blue, N; Gray and Green, C. Hydrogen atoms are omitted for clarity.

pore via π−π interaction (Figure 2c). Interestingly, unlike the o-xylene system, m-xylene was encapsulated along the channel direction and formed a strong interaction with adjacent four TAPP molecules core via hydrogen bond interaction (Figures 2d and S6). Thanks to the multi-interactive and high symmetric structure of TAPP, we successfully constructed the higher indexed crystal. The TAPPcube (Monoclinic, P21/c) crystal obtained from p-xylene/ethanol system possesses the columnar stacking structure of TAPP and has strong C−H interaction with p-xylene along with a axis (Figure 2e and f). Unlike o- and m-xylene, p-xylene showed strong C−H interactions between the benzene ring of xylene and TAPP molecules. The benzene ring of xylene showed interactions with the four adjacent TAPPs. In addition, the methyl group of xylene showed additional interactions via hydrogen bonds with the adjacent aminophenyl group (Figure S7). These results indicate that the different molecular geometry of antisolvent inherently influences the interaction strength, stability, and crystallization process that gives a significant effect on the final morphology determination (Figure 3 and Figure S9). In the o-xylene case, crystals grown by the ASC and r-ASC process have the same crystal structure (Figure S10). Because o-xylene has a weak interaction with TAPP molecules, direct participation of o-xylene in the crystal seems to be difficult although it was added first during the r-ASC process. Therefore, ethanol interacts preferentially with TAPP instead of o-xylene to finally form rod-shaped crystals. However, oxylene seems to clearly affect the size of TAPProd and it means o-xylene influences the nucleation and growth environment although o-xylene may not participate in crystal directly (Figure S11). On the contrary, m- and p-xylene participate directly in the crystallization by making interactions with TAPP when they are added first. At this time, due to the geometry of xylene, the number of sites that interact with

Figure 3. Schematic illustration of the growth mechanism of TAPProd, TAPPdisk, and TAPPcube. In the TAPProd case, o-xylene could not interact with TAPP, although it was added first, so ethanol bonds with TAPP to grow rod-shaped crystal. In the TAPPdisk and TAPPcube case, m- and p-xylene formed bonds when they were added first, but their different molecular geometry induced different numbers of bonding sites, thus changing morphological dimensions.

TAPP are different, which affects the final morphology. In the m-xylene case, the meta-positioned methyl group only interacts with two TAPP, but in the p-xylene case, not only the methyl group but also the benzene ring interacts with six TAPPs. This result clearly demonstrates that the degree of interaction between solvent and solute could be varied by the molecular geometry of the antisolvent, and then, crystal morphology is determined, especially for polyhedral crystals. Therefore, our strategy gives an opportunity to design crystallization of organic molecular polyhedral crystals by using proper solvent molecular geometry without any nonsolvent chemical additives. Although we unveiled the effect of the solvent C

DOI: 10.1021/acs.cgd.8b01294 Cryst. Growth Des. XXXX, XXX, XXX−XXX

Crystal Growth & Design

Communication

Notes

addition order and different antisolvent geometry on the control of the local environment during the crystallization that eventually determines the morphology of the resulting crystal, it still lacks a more accurate explanation about the microscopic crystal growth mechanism. For example, more accurate information about the moments of supersaturation/nucleation occurring when a solute/antisolvent mixture meets good solvent needs to be further elucidated, because it seems that the dispersed solute in antisolvent undergoes a certain intermediate state that can control the local supersaturation environment when the good solvent comes in. The intermediate states corresponding to each different solvent seem to eventually affect the crystallization into specific morphologies. Therefore, we are currently focusing on the elucidation of the identity of the local supersaturation environment. In conclusion, we demonstrated the morphology control of TAPP crystals from rod (TAPProd), disk (TAPPdisk), to cube (TAPPcube) by the r-ASC process. First of all, the solvent addition order has a significant effect on the determination of the morphology of resulting crystals. Especially, we proved that the first added antisolvent played a critical role in forming various crystal morphologies unlike the general ASC process that has limited interactions of good solvent and solute. Furthermore, we also proved that the interaction between the antisolvent and TAPP could be varied depending on the molecular geometry of the antisolvent. For the o-xylene case, it has a weak interaction with TAPP, so ethanol has a strong interaction with TAPP, and then, TAPProd was grown. However, for m- and p-xylene cases, each solvent interacts at numerous interacting sites to TAPP molecules, which induce TAPPdisk and TAPPcube, respectively. The additive-free organic molecular crystal growth into polyhedron is meaningful as it reveals a detailed correlation between the solvent−solute interaction and crystal morphology, especially polyhedron, through which further extended crystallization methods could be developed.

■

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS Single crystal and powder XRD measurements were performed at Beamline 2D and 5D of the Pohang Accelerator Laboratory (PAL), Korea.

■

(1) Choi, K.-S. Shape Control of Inorganic Materials via Electrodeposition. Dalt. Trans. 2008, 0, 5432−5438. (2) Jun, Y. W.; Seo, J. W.; Sang, J. O.; Cheon, J. Recent Advances in the Shape Control of Inorganic Nano-Building Blocks. Coord. Chem. Rev. 2005, 249, 1766−1775. (3) Kim, J.; Park, C.; Song, I.; Lee, M.; Kim, H.; Choi, H. C. Unique Crystallization of Fullerenes: Fullerene Flowers. Sci. Rep. 2016, 6, 1− 8. (4) Park, C.; Park, J. E.; Choi, H. C. Crystallization-Induced Properties from Morphology-Controlled Organic Crystals. Acc. Chem. Res. 2014, 47, 2353−2364. (5) Park, C.; Yoon, E.; Kawano, M.; Joo, T.; Choi, H. C. SelfCrystallization of C70 Cubes and Remarkable Enhancement of Photoluminescence. Angew. Chem., Int. Ed. 2010, 49, 9670−9675. (6) Park, J. E.; Son, M.; Hong, M.; Lee, G.; Choi, H. C. CrystalPlane-Dependent Photoluminescence of Pentacene 1D Wire and 2D Disk Crystals. Angew. Chem., Int. Ed. 2012, 51, 6383−6388. (7) Kim, H.; Son, Y.; Lee, J.; Lee, M.; Park, S.; Cho, J.; Choi, H. C. Nanocomb Architecture Design Using Germanium Selenide as HighPerformance Lithium Storage Material. Chem. Mater. 2016, 28, 6146−6151. (8) Si, R.; Flytzani-Stephanopoulos, M. Shape and Crystal-Plane Effects of Nanoscale Ceria on the Activity of Au-CeO2 Catalysts for the Water-Gas Shift Reaction. Angew. Chem., Int. Ed. 2008, 47, 2884− 2887. (9) Guo, P.; Chen, P.; Ma, W.; Liu, M. Morphology-Dependent Supramolecular Photocatalytic Performance of Porphyrin Nanoassemblies: From Molecule to Artificial Supramolecular Nanoantenna. J. Mater. Chem. 2012, 22, 20243−20249. (10) Zhong, Y.; Wang, Z.; Zhang, R.; Bai, F.; Wu, H.; Haddad, R.; Fan, H. Interfacial Self-Assembly Driven Formation of Hierarchically Structured Nanocrystals with Photocatalytic Activity. ACS Nano 2014, 8, 827−833. (11) Liu, Y. Z.; Lai, W. P.; Yu, T.; Ma, Y. D.; Kang, Y.; Ge, Z. X. Understanding the growth morphology of explosive crystals in solution: insights from solvent behavior at the crystal surface. RSC Adv. 2017, 7, 1305−1312. (12) Wang, J.; Li, B.; Yersak, T.; Yang, D.; Xiao, Q.; Zhang, J.; Zhang, C. Recent Advances in Pt-Based Octahedral Nanocrystals as High Performance Fuel Cell Catalysts. J. Mater. Chem. A 2016, 4, 11559−11581. (13) Luo, H.; Zhou, J.; Zhong, H.; Zhou, L.; Jia, Z.; Tan, X. Polyhedron Cu2O@Ag Composite Microstructures: Synthesis, Mechanism Analysis and Structure-Dependent SERS Properties. RSC Adv. 2016, 6, 99105−99113. (14) Pileni, M. P. The Role of Soft Colloidal Templates in Controlling the Size and Shape of Inorganic Nanocrystals. Nat. Mater. 2003, 2, 145−150. (15) Umemura, A.; Diring, S.; Furukawa, S.; Uehara, H.; Tsuruoka, T.; Kitagawa, S. Morphology Design of Porous Coordination Polymer Crystals by Coordination Modulation. J. Am. Chem. Soc. 2011, 133, 15506−15513. (16) Lee, S. M.; Cho, S. N.; Cheon, J. Anisotropic Shape Control of Colloidal Inorganic Nanocrystals. Adv. Mater. 2003, 15, 441−444. (17) Yang, S. H.; Lin, Z. Q.; Shi, N. E.; Jin, L. Z.; Yu, M. N.; Xie, L. H.; Yi, M. D.; Huang, W. A Polyhedral Supramolecular System of Endocyclic Crystalline Organic Nanostructures: The Case of Triptycenes. CrystEngComm 2015, 17, 1448−1452.

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.cgd.8b01294. General experimental information, synthesis, and evaluation of products (PDF) Accession Codes

CCDC 1858372, 1858377, and 1858739 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/ data_request/cif, or by emailing [email protected]. uk, or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

■

REFERENCES

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Hee Cheul Choi: 0000-0003-1002-1262 Author Contributions #

Y. P. and J. Y. K. contributed equally. D

DOI: 10.1021/acs.cgd.8b01294 Cryst. Growth Des. XXXX, XXX, XXX−XXX

Crystal Growth & Design

Communication

(18) Lin, Z. Q.; Sun, P. J.; Tay, Y. Y.; Liang, J.; Liu, Y.; Shi, N. E.; Xie, L. H.; Yi, M. D.; Qian, Y.; Fan, Q. L.; et al. Kinetically Controlled Assembly of a Spirocyclic Aromatic Hydrocarbon into Polyhedral Micro/Nanocrystals. ACS Nano 2012, 6, 5309−5319. (19) Zhang, X.; Dong, C.; Zapien, J. A.; Ismathullakhan, S.; Kang, Z.; Jie, J.; Zhang, X.; Chang, J. C.; Lee, C.-S.; Lee, S.-T. Polyhedral Organic Microcrystals: From Cubes to Rhombic Dodecahedra. Angew. Chem., Int. Ed. 2009, 48, 9121−9123. (20) Kang, L.; Fu, H.; Cao, X.; Shi, Q.; Yao, J. J. Am. Chem. Soc. 2011, 133, 1895−1901. (21) Park, Y.; Hong, M.; Koo, J. Y.; Lee, M.; Lee, J.; Moon, D. J.; Sohn, S. H.; Joo, T.; Lim, W. T.; Lim, H.; et al. Reverse Anti-Solvent Crystallization Process for the Facile Synthesis of Zinc Tetra(4Pyridyl)Porphyrin Single Crystalline Cubes. Sci. Rep. 2017, 7, 1−8. (22) Kim, J.; Park, C.; Choi, H. C. Selective Growth of C70 Crystal in a Mixed Solvent System: From Cube to Tube. Chem. Mater. 2015, 27, 2408−2413. (23) Huang, L.; Liao, Q.; Shi, Q.; Fu, H.; Ma, J.; Yao, J. Rubrene Micro-Crystals from Solution Routes: Their Crystallography, Morphology and Optical Properties. J. Mater. Chem. 2010, 20, 159−166. (24) Liu, D. D.; Yu, N. S.; Liu, D. P.; He, Y. Y.; Liu, R.; Li, Q. J.; Liu, B.; Liu, B. B. The Effect of Trichlorobenzene Solvent Geometry on the Morphologies of C60 Nano/Microcrystals Produced from Solution. Mater. Res. Bull. 2016, 73, 65−69. (25) Park, C.; Song, H. J.; Choi, H. C. The Critical Effect of Solvent Geometry on the Determination of Fullerene (C60) Self-assembly into Dot, Wire, and Disk Structures. Chem. Commun. 2009, 4803− 4805.

E

DOI: 10.1021/acs.cgd.8b01294 Cryst. Growth Des. XXXX, XXX, XXX−XXX