MetalâOrganic Frameworks as Supramolecular Templates for

Article pubs.acs.org/crystal

Metal−Organic Frameworks as Supramolecular Templates for Directing Aromatic Packing Motifs Liubov M. Lifshits,† Matthias Zeller,‡ Charles F. Campana,§ and Jeremy K. Klosterman*,†,# †

Center for Photochemical Sciences, Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403, United States ‡ Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States § Bruker AXS, Inc., Madison, Wisconsin 53711-5373, United States S Supporting Information *

ABSTRACT: Modular methods to direct the molecular packing of aromatic organic chromophores are essential for understanding the subtle principles needed to predict intermolecular interactions and design uniform, efficient organic optoelectronic devices. Here we demonstrate that layered twodimensional metal−organic frameworks, based on the copper paddlewheel and 5-aryl isophthalate ligands, can alter the interstitial packing of the aryl groups and template new packing motifs for the small acenes.

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INTRODUCTION The controlled packing of organic chromophores is critical for optoelectronic materials dependent on efficient energy transfer and charge transport such as organic semiconductor crystals1,2 field-effect transistors,3 and photonic devices.4,5 Extensive experimental and computational investigations of the packing of aromatic molecules, i.e., polythiophenes and acenes, such as anthracene and pentacene, have emphasized the importance of cofacial π-orbital overlap.6−10 Current efforts to maximize orbital interactions in assemblies of stacked aromatic molecules11 often rely on simplified “charge-transfer” interactions12−14 between electron-rich and electron-poor aromatic rings.15 In the case of weakly polar aromatics, alkyl chains and hydrogen bonding motifs are often attached as supramolecular synthons to direct the stacking interactions.16,17 Cocrystals (including solvates and organic salts) have also been used to direct packing motifs of aromatic molecules in molecular crystals,18−21 yet these methods still suffer from a lack of a priori predictability. Metal−organic frameworks (MOFs) are predictable, crystalline materials with potential applications ranging from gas storage,22,23 separation,24 and optoelectronic devices,25 as the bulk properties can be tuned at the molecular level through reticular syntheses,26 postsynthetic modification,27 or solventassisted ligand exchange procedures.28 The periodic, long-range order in MOFs offers a unique scaffold where large arrays of ordered chromophores can be constructed.29−31 Indeed, several groups have reported the incorporation of photoactive MOF ligands, containing Ru(bipy)3,32−38 porphyrin,39−41 and perylenediimide moieties,42 into well-spaced highly porous MOF © 2017 American Chemical Society

structures where Förster-type energy transport occurs via short and long-range hopping between weakly coupled ligand chromophores.43,44 In molecular crystals, however, close van der Waals contacts between stacked aromatics lead to strong electronic coupling and rapid energy transport over long (micrometer) distances.45−47 Accordingly, MOFs showing efficient carrier transport typically exhibit cofacial stacking between redoxactive ligands.48,49 Recently we reported a supramolecular strategy for directing the assembly of 5-(carbazol-9-yl) isophthalate chromophores 1 within laminar two-dimensional (2D) metal−organic frameworks.50 Here we expand upon our strategy and demonstrate that square grids of isophthalate MOFs serve as a general template for directing the packing motifs of small aromatic chromophores, including the simple acenes naphthalene and anthracene (Scheme 1). Our approach utilizes 2D frameworks, which assemble from dimetallic copper paddlewheel secondary building units (SBUs) and functionalized isophthalic acids, as supramolecular building blocks (SBBs) to generate three-dimensional (3D) laminar MOFs where tethered aromatic chromophores interdigitate to form aromatic stacks in the interstitial spaces. Previously, we demonstrated that varying the metal identity and SBU geometry (i.e., Cu(II), Co(II), and Zn(II)) could be used to direct the interlayer packing motifs of the pendant carbazole chromophores of 5-(carbazol-9-yl) isophthalate 1 from oneReceived: July 9, 2017 Published: August 23, 2017 5449

DOI: 10.1021/acs.cgd.7b00954 Cryst. Growth Des. 2017, 17, 5449−5457

Crystal Growth & Design

Article

blue hexagonal platelets as [Cu2(NapBDC)2(DMA)2]n again in space group P21/c. Cu CbzMOF crystallized in green rhombohedral platelets as [Cu2(CbzBDC)2(NMP)2]n in C2/c. PXRD spectra were recorded for all MOF materials to ensure phase purity. See Supporting Information for full synthetic procedures, characterization, and crystallographic data tables.

Scheme 1. Assembly of 3D Laminar MOFs with Interstitial Aromatic Stacks from 2D MOF Supramolecular Building Block (SBB) Layers of Functionalized Isophthalic Acidsa

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RESULTS AND DISCUSSION Crystal Structures of Ligands 1a and 2a. Distorted isophthalate ligands are often observed within MOF networks,63 and Zaworotko and co-workers hypothesized that bulky substituents at the 5-position can induce twisting in the isophthalate ring and give rise to alternate MOF topologies.62,64,65 The large aryl groups in ligands 1−4 necessitate twisted, nonplanar conformations between the two aryl groups.60 Single crystals of the dimethyl ester anthracenyl ligand precursor 2a were obtained by slow solvent diffusion and analyzed by X-ray diffraction (Figures 1a and S20a). The crystal a

Molecular structures and abbreviations of 5-aryl-isophthalic acid subunits used in this study.

dimensional (1D) π-stacks, offset π-diads, to an unusual wellspaced packing motif where, in the absence of cofacial πoverlap, enhanced solid-state emission was observed. In this report we now vary the size and electronic profile of the aromatic chromophore and detail the influence of the chromophore identity upon the final packing motifs. The new 5-aryl isophthalate ligands were modified to include anthracene, a prototypical acene chromophore51−53 extensively used as a supramolecular building block54 which adopts a herringbone packing motif in the crystalline state;56 acridine, which provides a similarly sized chromophore backbone55 with an embedded nitrogen atom that reduces the acene π-electron cloud, adds a dipole moment and favors the formation of antiparallel stacks;56−58 and naphthalene, the smallest polycyclic aromatic which favors the herringbone motif,59 at the surfaces of 2D MOF layers. Within the steadfast laminar MOF template, the packing motifs of the tethered aromatics were altered to favor greater cofacial overlapnecessary for efficient optoelectronic applications.

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Figure 1. Crystal structures showing the packing and charge-transfer (CT) interactions between the electron-deficient isophthalates and “electron-rich” carbazole and anthracene chromophores of CbzBDC 1a and AntBDC 2a. The (a) head-to-tail CT stacks of 1a generate (b) a repeating 2D infinite-stack motif (top view shown), whereas (c) the self-complementary CT interactions of 2a give rise to (d) a 1D columnar motif (top view shown).

EXPERIMENTAL SECTION

Ligand Syntheses. The new isophthalate ligands, 5-(anthracen-9yl)isophthalic acid 2, 5-(acridin-9-yl)isophthalic acid 3, and 5(naphthalen-1-yl)isophthalic acid 4, were prepared using SuzukiMiyuara coupling conditions in good overall yields from dimethyl 5pinacolatoboronic ester isophthalate and 9-bromoanthracene, 9chloroacridine and 1-chloronaphthalene, respectively, followed by basic hydrolysis. All new ligands were fully characterized by NMR and mass spectrometry. Single crystals of the dimethyl ester of the anthracenyl ligand 2a were obtained by slow solvent diffusion and analyzed by X-ray diffraction. The crystal structure of the dimethyl ester of the carbazolyl ligand 1a was previously reported and is included for comparison.50,60 See Supporting Information for full synthetic procedures and characterization. MOF Syntheses. Treating 5-Ar isophthalic acid ligands 2−4 with copper nitrate in DMA/EtOH solvent mixtures and heating over several days provided single crystals suitable for single crystal X-ray diffraction (SC-XRD) analyses. Pyridine was added as a modulator to aid crystal growth as needed but was not incorporated into the final MOF structures.61,62 Cu AntMOF crystallized in green rhombohedral platelets as [Cu2(AntBDC)2(DMA)2]n. Single crystal X-ray crystallography revealed that the layered Cu AntMOF adopts space group P21/ c. Cu AcrMOF crystallized in blue hexagonal rods as [Cu2(AcrBDC)2(EtOH)2·EtOH1.2]n in space group Pbca. Cu NapMOF crystallized in

structure of the dimethyl ester carbazolyl ligand precursor 1a was previously reported and is included for comparison (Figures 1b and S20a).50,60 As expected, the larger anthracene chromophore requires a greater deviation from coplanarity with the isophthalate ring, ∼66° and ∼45° for AntBDC 2a and CbzBDC 1a respectively, due to the angle of the 1- and 8hydrogen atoms in the fjord region (Table S2). Bending and twisting distortions of the carboxylate groups of isophthalic acids are common,64 yet in the ligand ester precursors, the carbonyl groups of CbzBDC 1a and AntBDC 2a are nearly coplanar with the isophthalate ring, where α = 7.21°/6.70° and 8.26°/11.07° for CbzBDC 1a (there are two molecules in the asymmetric unit) and α = 12.74° for AntBDC 2a. The crystal packing of dimethyl ester ligand precursors 1a and 2a is dominated by π-stack motifs between electron-poor isophthalate moieties and the electron-rich carbazole or anthracene chromophores of neighboring molecules.12,13 In CbzBDC 1a the two molecules of the asymmetric unit form a 5450



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Figure 2. Single crystal X-ray structures of Cu CbzMOF, Cu AntMOF, Cu AcrMOF, and Cu NapMOF. (a) Front view shows the isostructural square grid (sql) layers with pendant carbazole, anthracene, acridine, and naphthalene chromophores represented by violet, yellow, light blue, and pink spheres, respectively. (b) Top and (c) side views show the laminar 3D structure with the isophthalate backbone of the 2D layers in blue and interdigitated aromatic chromophores in color-coded space filling. Coordinated solvent molecules and disordered atoms removed for the sake of clarity.

head to tail stack with the carbazole slightly offset so that the center of carbazole ring A sits 3.47 Å (center of gravity (Cg)− C15 distance) above the isophthalate ring (Figure 1a). The infinite head-to-tail stacks propagate along the crystallographic a-axis and with neighboring molecules along the b-axis (Figure 1b). The anthracenyl ligand AntBDC 2a, on the other hand, forms a self-complementary offset stacking motif with closest contacts, 3.15 Å (O1−C9a), between carbonyl oxygen atoms of the isophathalate and flanking anthracene rings (Figure 1c). The next molecule fits on the opposite face of the anthracene through similar interactions to form 1D columns propagated along the vector of the c-axis (Figure 1d). In both cases, apparent “polar-π” interactions are likely best ascribed to local, direct interactions involving the ester substituents.14,66,67 Regardless of their exact nature, these interactions in the solid powders of CbzBDC 1a and AntBDC 2a give rise to broad, low-energy charge-transfer (CT) absorptive transitions in the diffuse reflectance UV−vis spectra (Figure 7). MOF Structures and Topology. Single crystal X-ray crystallography was used to establish that all 5-aryl isophthalate Cu MOFs are laminar 3D materials of isostructural 2D squaregrid (sql) layers of isophthalates, connected through the dimetallic copper paddlewheel SBU, held together by intercalated aromatic chromophores in a manner reminiscent of double-sided velcro (Figure 2). The isophthalate layers are remarkably similar; each ∼0.8 nm thick and separated by ∼0.5 nm of interstitial space filled with interdigitated chromophores

(Figure S27). In Cu CbzMOF, the 2D layers adopt a staggered A−B−A packing arrangement, ordering the interlayer carbazoles into columns, whereas the 2D layers in Cu AntMOF, Cu AcrMOF, and Cu NapMOF remain aligned with interlayer chromophores offset (Figure 2b). The 2D layers are composed of repeating rhombohedral motifs defined by four isophthalate units (only one per crystallographic asymmetric unit except for Cu NapMOF, which has two crystallographically distinct isophthalate ligands) and four copper square paddlewheel SBUs at each vertex (Figure 3, Figure S28 and Table S4). The isophthalates are arranged in an up, up, down, down orientation62 such that the connecting nitrogen atoms of 1 and carbon atoms of 2−4 are held 6.98−7.70 Å apart in columns along the face of each 2D layer (Figure 2a). Contrary to previous observations,62,65 the sql grids of Cu MOFs reported here are topologically equivalent even with large aryl-substituents and significant ligand distortion. As expected for sterically congested diaryls, the 5-aryl substituents adopt twisted conformations ranging from 55° for carbazole to 89° for anthracene (Figure 3 and Table S5). For these two extremes, the diaryl torsion angles observed in the MOF structures, Cu CbzMOF and Cu AntMOF, are greater than in crystals of the free ester ligand precursors 1a and 2a, 55° vs 45° and 89° vs 65° respectively. Although similar in size to anthracene, the diaryl torsion for the acridine chromophore in Cu AcrMOF is smaller at 76°. 5451



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Figure 3. Repeating rhombohedral motifs in the SBB layers of (a) Cu CbzMOF, (b) Cu AntMOF, (c) Cu AcrMOF, and (d) Cu NapMOF−motif A (vide infra). Coordinated solvent molecules and disordered atoms removed for the sake of clarity.

Nevertheless, only the isophthalate ligands in Cu AcrMOF exhibit significant isophthalate distortion. The isophthalate rings bend such that the plane of one carboxylate is no longer coplanar with the isophthalate ring by ∼10° and facilitates distortion of the 2D MOF layers into orthorhombic symmetry (Figure S29 and Table S5). Further twisting occurs at the corners of the copper SBU where the planes of two opposing carboxylates are tilted 15° away from the prototypical head-on 180° chelating geometry. Given the similar profiles of all four aryl substituents, it is apparent that deviations in the sql layer and isophthalate ligand geometries arise from interlayer interactions involving the interstitial chromophores. Interlayer Aromatic Packing. The 2D sql layers assemble to form 3D laminar solids, which direct, and are held together by, intermolecular interactions between aromatic chromophores of opposing layers. The syn-up or syn-down orientation of neighboring isophthalates aligns the pendant chromophores in alternating columns along the top and bottom faces of each layer (Figure 2a). The columnar arrangements of aromatics of the opposing layers interdigitate to generate unusual packing motifs not observed in crystals of the parent aromatic chromophores59 (Figure 4). The pendant carbazoles in Cu CbzMOF form columns of head-to-tail face-to-face stacks (Figure 4a). Within the columnar stacks, the carbazoles segregate into coplanar, stacked pairs (Figure 5a). The head-to-tail short axes of the carbazoles in the pairs are not perfectly antiparallel but offset 1.31 Å sideways in a slipped-stack fashion (Figure 5c). The centroid− centroid distances of the flanking six-membered rings are 3.94 Å, whereas centroids for the central five-membered rings are closer at 3.88 Å. Each stacked pair is tilted 9.41° and rotated 13.48° relative to neighboring stacked pairs in the columns. As a result, the flanking centroid distances increase to 4.01 and 4.34 Å, but the central centroids remain close at 3.87 Å due to the rigid MOF scaffold. The 2D isophthalate layers of Cu AntMOF are isostructural with those in Cu CbzMOF, yet differences in the aryl−aryl torsion angles, 55° vs 89°, and layer offset (Figure 2b) go handin-hand with a pointedly different packing arrangement (Figure

Figure 4. Projections showing interstitial aromatic chromophore packing motifs in (a) Cu CbzMOF (head to tail cofacial stacks), (b) Cu AntMOF (sandwich herringbone), (c) Cu AcrMOF (gamma γ) and (d) sandwich herringbone and (e) slipped sandwich packing motifs arising from naphthalene disorder in single crystals of Cu NapMOF. Chromophores are colored purple, yellow, light blue, and pink, respectively, with chromophores of the opposing layers colored green.

4b). 1,2-Syn anthracenes adopt a zigzag orientation, tilted 82.5°, along the crystallographic c-axis vector, in contrast to the parallel clefts in Cu CbzMOF. Sandwich herringbone-like packing motifs are formed in the interstitial spaces upon intercalation of anthracenes from opposing layers (Figure 6). The best-fit planes of the anthracene diads are coplanar, separated by 3.77 Å, and slightly offset. Neighboring anthracene diads interlock via selfcomplementary edge-to-face (best described as CH···C contacts of 2.62 Å between syn-up neighbors and 3.01 Å between opposing layers) and face-to-face (∼3.3 Å between 5452



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Figure 7. Normalized absorption and diffuse reflectance spectra showing broadening and red-shifts arising from CT interactions involving the 5-aryl chromophores and electron-poor isophthalate rings observed in solid powders of (a) CbzBDC 1a and (b) AntBDC 2a relative to the free ligands in cyclohexane solution (CH) and crystals of Cu CbzMOF and Cu AntMOF, respectively. Copper based transitions in Cu CbzMOF and Cu AntMOF appear above ca. 550 nm.

Figure 5. Intermolecular contacts of intercalated carbazoles in Cu CbzMOF. (a) Front and (b) side projections of head-to-tail carbazole stacks showing intermolecular contacts (as centroid−centroid distances) and angles, respectively. (c) Top projections showing offset in a single stacked pair and rotation between stacked pairs. Opposing layers are colored violet and gray. Ellipsoids are set at 50% probability.

orientation tilted 73.1° propagated along the crystallographic baxis through CH···C contacts of 2.65 Å (Figure 4c). However, interdigitation of layers forms a gamma (γ) packing motif where opposing acridines assemble into infinite slipped stacks along the crystallographic a-axis (Figure 8). The acridines from

Figure 6. Intermolecular contacts of interdigitated anthracenes in Cu AntMOF. (a) Front projection of sandwich-herringbone packing motifs with intermolecular CH···C contacts (orange lines) and distances between best-fit-planes (red arrows). (b) Side projection along the diad plane showing orientation of neighboring diads. (c) Top view of anthracene diad showing offset. Opposing layers are colored yellow and gray. Ellipsoids are set at 50% probability.

Figure 8. Intermolecular contacts between acridines in Cu AcrMOF. (a) Front projection of slip-stack packing motifs with intermolecular CH···C contacts (orange lines) and distances between best-fit-planes (red arrows). (b) Side projection along the diad plane showing orientation of neighboring diads. (c) Top view of acridine diad showing offset. Opposing layers are colored light-blue and gray. Ellipsoids are set at 50% probability.

best-fit-planes) interactions in a manner reminiscent of the terpyridine embrace.68,69 Within in the crystalline matrices of Cu CbzMOF and Cu AntMOF, the “polar-π” aromatic interactions involving the electron-poor isophthalate groups that guided the molecular packing of the free ligands CbzBDC 1a and AntBDC 2a are now superseded by the rigid Cu MOF scaffold. Accordingly, the low energy CT transitions observed in the diffuse reflectance (DR) spectrum of Cu CbzMOF and Cu AntMOF narrow and shift to higher energies (Figure 7). The acridine chromophores in AcrBDC 3 are similar in steric profile to the anthracenes of AntBDC 2 but adopt a slightly smaller diaryl torsion angle of 76° in the crystal structure of Cu AcrMOF. Syn-up (or down) acridines also adopt a zigzag

opposing layers in the slipped stacks are twisted 17.2° and offset such that only the flanking benzene rings overlap with 3.87 Å between best-fit-planes. Further CH···C contacts of 3.25 Å exist between opposing anthracenes in neighboring zigzags. The nitrogen atoms of the acridine heterocycles form complementary H-bonds with an ethanol (or water) coordinated to the nearby copper SBU of the adjacent layer to further stabilize the laminar structure (Figure 9 and Table 1). Presumably the extensive interlayer hydrogen-bond network at each SBU and acridine provides the driving force to alter the 5453



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naphthalenes are nearly coplanar, but rotated 173.1° to form an alternating aromatic cleft ∼7.37 Å apart (Figure 11).

Figure 9. Interlayer H-bonds between acridines and coordinated solvent molecules in Cu AcrMOF. Ellipsoids are set at 50% probability.

Table 1. Hydrogen-Bond Geometry (Å, °) in Cu AcrMOF D−H···A

D−H

H···A

D···A

D−H···A

O5−H5A···N37

0.82 (2)

1.95 (2)

2.761 (2)

175.01

packing motif, relative to Cu AntMOF, and distort the 2D MOF geometry (Figure 2a). The naphthalene chromophores on NapBDC 4 offer the smallest π-surface of the chromophores studied and connection at the 1-position of naphthalene generates the potential for dissymmetric conformers to be trapped within the MOF matrix. Thus, it is not surprising that the interstitial naphthalenes within the crystal structure of Cu NapMOF are 1:1 disordered between the sandwichherringbone motif A (Figure 4d) of Cu AntMOF and Cu AcrMOF and a slipped sandwich packing motif B (Figure 4e) suggestive of Cu CbzMOF. In motif A, the syn-naphthalenes are tilted 81.0° in a zigzag manner along the crystallographic a-axis with alternating CH···C contacts of 3.12 Å due to the asymmetric profiles of the naphthalen-1-yl groups (Figure 10). Interdigitation of naphthyl substituents of opposing layers results in interlayer head-to-tail sandwich diads of 4.64 and 3.99 Å (distances between best-fit-planes) arranged in a herringbone motif. In motif B, the syn-

Figure 11. Intermolecular contacts of naphthalenes in the slipped sandwich packing motif B of Cu NapMOF (a) Front projection with intermolecular C···C contacts (orange lines) and distances between best-fit-planes (red arrows). (b) Side projection showing tilting of stacked pairs. (c) Top view of the two naphthalene cofacial stacked diads showing offset. Diads I are tiled 6.9° relative to diads II. Opposing layers are colored pink and gray. Ellipsoids are set at 50% probability.

Naphthalenes of the opposing layer intercalate to form two slipped sandwich pairs I and II. Crystallographically, it is difficult to determine if the two motifs are intermixed within a single interstitial space or are segregated into alternating interlayer spaces. As the primary difference between the two motifs involves diad I rotating by ∼60°, where it occupies a similar volume, intermixing of motifs in the space between two layers is also possible (Figure S31d).

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CONCLUSIONS Directing the hierarchical assembly of functional materials to discover the underlying organizing principles and intermolecular interactions that give rise to emergent bulk optoelectronic properties is a fundamental challenge in solid-state hybrid materials. The predictable topologies of metal−organic frameworks offer an ideal platform to control the assembly of push− pull organic chromophores to design, a priori, dense arrays needed for organic optoelectronic materials. Here we described a general extension of our supramolecular building block strategy where square grids of 5-functionalized isophthalate MOFs direct new packing motifs of interdigitated, organic aromatic chromophores. Anthracene, acridine, carbazole, and naphthalene were directed into cofacial stacks and diads within the crystalline MOFs and the interplay of intermolecular interactions and MOF structure examined, using single crystal X-ray diffraction, to establish the effects of chromophore size and heteroatoms. In the absence of the directing MOF framework, the packing of the free ester ligands is dominated by polar-π type charge-transfer interactions between electronpoor isophthalates and the aromatic chromophore; clearly

Figure 10. Intermolecular contacts of naphthalenes in the sandwichherringbone motif A in Cu NapMOF. (a) Front projection with intermolecular CH···πCg contacts (orange lines) and distances between best-fit-planes (red arrows). (b) Side projection showing orientation of stacked pairs. (c) Top view of the two cofacial stacked diads showing offset. Diads I are parallel with the crystallographic a-axis whereas diads II run perpendicular. Opposing layers are colored pink and gray. Ellipsoids are set at 50% probability. 5454



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(9) Brédas, J.-L.; Norton, J. E.; Cornil, J.; Coropceanu, V. Molecular Understanding of Organic Solar Cells: The Challenges. Acc. Chem. Res. 2009, 42 (11), 1691−1699. (10) Feng, X.; Marcon, V.; Pisula, W.; Hansen, M. R.; Kirkpatrick, J.; Grozema, F.; Andrienko, D.; Kremer, K.; Müllen, K. Towards high charge-carrier mobilities by rational design of the shape and periphery of discotics. Nat. Mater. 2009, 8 (5), 421−426. (11) Klosterman, J. K.; Yamauchi, Y.; Fujita, M. Engineering discrete stacks of aromatic molecules. Chem. Soc. Rev. 2009, 38 (6), 1714− 1725. (12) Hunter, C. A.; Lawson, K. R.; Perkins, J.; Urch, C. J. Aromatic interactions. J. Chem. Soc. Perkin Trans. 2 2001, No. 5, 651−669. (13) Martinez, C. R.; Iverson, B. L. Rethinking the term “pi-stacking. Chem. Sci. 2012, 3 (7), 2191−2201. (14) Wheeler, S. E.; Bloom, J. W. G. Toward a More Complete Understanding of Noncovalent Interactions Involving Aromatic Rings. J. Phys. Chem. A 2014, 118 (32), 6133−6147. (15) Das, A.; Ghosh, S. Supramolecular Assemblies by ChargeTransfer Interactions between Donor and Acceptor Chromophores. Angew. Chem., Int. Ed. 2014, 53 (8), 2038−2054. (16) Pisula, W.; Feng, X.; Müllen, K. Tuning the Columnar Organization of Discotic Polycyclic Aromatic Hydrocarbons. Adv. Mater. 2010, 22 (33), 3634−3649. (17) Fang, X.; Yang, X.; Yan, D. Vapor-phase π−π molecular recognition: a fast and solvent-free strategy towards the formation of co-crystalline hollow microtube with 1D optical waveguide and upconversion emission. J. Mater. Chem. C 2017, 5 (7), 1632−1637. (18) Mei, X.; Liu, S.; Wolf, C. Template-Controlled Face-to-Face Stacking of Olefinic and Aromatic Carboxylic Acids in the Solid State. Org. Lett. 2007, 9 (14), 2729−2732. (19) Beaujuge, P. M.; Fréchet, J. M. J. Molecular Design and Ordering Effects in π-Functional Materials for Transistor and Solar Cell Applications. J. Am. Chem. Soc. 2011, 133 (50), 20009−20029. (20) Yan, D.; Delori, A.; Lloyd, G. O.; Frišcǐ ć, T.; Day, G. M.; Jones, W.; Lu, J.; Wei, M.; Evans, D. G.; Duan, X. A Cocrystal Strategy to Tune the Luminescent Properties of Stilbene-Type Organic SolidState Materials. Angew. Chem., Int. Ed. 2011, 50 (52), 12483−12486. (21) Sugino, M.; Araki, Y.; Hatanaka, K.; Hisaki, I.; Miyata, M.; Tohnai, N. Elucidation of Anthracene Arrangement for Excimer Emission at Ambient Conditions. Cryst. Growth Des. 2013, 13 (11), 4986−4992. (22) Murray, L. J.; Dincă, M.; Long, J. R. Hydrogen storage in metal−organic frameworks. Chem. Soc. Rev. 2009, 38 (5), 1294−1314. (23) Sumida, K.; Rogow, D. L.; Mason, J. A.; McDonald, T. M.; Bloch, E. D.; Herm, Z. R.; Bae, T.-H.; Long, J. R. Carbon Dioxide Capture in Metal−Organic Frameworks. Chem. Rev. 2012, 112 (2), 724−781. (24) Li, J.-R.; Sculley, J.; Zhou, H.-C. Metal−Organic Frameworks for Separations. Chem. Rev. 2012, 112 (2), 869−932. (25) Allendorf, M. D.; Bauer, C. A.; Bhakta, R. K.; Houk, R. J. T. Luminescent metal−organic frameworks. Chem. Soc. Rev. 2009, 38 (5), 1330−1352. (26) Yaghi, O. M.; O’Keeffe, M.; Ockwig, N. W.; Chae, H. K.; Eddaoudi, M.; Kim, J. Reticular synthesis and the design of new materials. Nature 2003, 423 (6941), 705−714. (27) Cohen, S. M. Postsynthetic Methods for the Functionalization of Metal−Organic Frameworks. Chem. Rev. 2012, 112 (2), 970−1000. (28) Deria, P.; Mondloch, J. E.; Karagiaridi, O.; Bury, W.; Hupp, J. T.; Farha, O. K. Beyond post-synthesis modification: evolution of metal−organic frameworks via building block replacement. Chem. Soc. Rev. 2014, 43 (16), 5896−5912. (29) Wang, J.-L.; Wang, C.; Lin, W. Metal−Organic Frameworks for Light Harvesting and Photocatalysis. ACS Catal. 2012, 2 (12), 2630− 2640. (30) García, H.; Ferrer, B. Photocatalysis by MOFs. In RSC Catalysis Series; Llabrés i Xamena, F., Gascon, J., Eds.; Royal Society of Chemistry: Cambridge, 2013; Chapter 12, pp 365−383.

shown in the SC-XRD and diffuse reflectance UV−vis analyses of carbazole 1a and anthracene 2a.

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.cgd.7b00954. Synthetic details and characterization for all ligands and MOF materials, including PXRD spectra, SC-XRD and detailed packing analyses (PDF) Accession Codes

CCDC 1547246−1547248 and 1547250 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], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Jeremy K. Klosterman: 0000-0003-4987-8060 Present Address #

Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was supported by Bowling Green State University and the BGSU Building Strength program. M.Z. acknowledges support by the National Science Foundation through the Major Research Instrumentation Program under Grant No. DMR 1337296, Ohio Board of Regents Grant CAP-491, and by Youngstown State University. The authors thank Bruce C. Noll of Bruker for assistance in preparing the CuAntMOF crystallography files for publication.

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REFERENCES

(1) Hutchison, G. R.; Ratner, M. A.; Marks, T. J. Intermolecular Charge Transfer between Heterocyclic Oligomers. Effects of Heteroatom and Molecular Packing on Hopping Transport in Organic Semiconductors. J. Am. Chem. Soc. 2005, 127 (48), 16866−16881. (2) Bredas, J. L.; Calbert, J. P.; da Silva Filho, D. A.; Cornil, J. Organic semiconductors: A theoretical characterization of the basic parameters governing charge transport. Proc. Natl. Acad. Sci. U. S. A. 2002, 99 (9), 5804−5809. (3) Hasegawa, T.; Takeya, J. Organic field-effect transistors using single crystals. Sci. Technol. Adv. Mater. 2009, 10 (2), 024314. (4) Clark, J.; Lanzani, G. Organic photonics for communications. Nat. Photonics 2010, 4 (7), 438−446. (5) Fuhrmann, T.; Salbeck, J. Organic Materials for Photonic Devices. MRS Bull. 2003, 28 (05), 354−359. (6) Anthony, J. E. Functionalized Acenes and Heteroacenes for Organic Electronics. Chem. Rev. 2006, 106 (12), 5028−5048. (7) Thorley, K. J.; Finn, T. W.; Jarolimek, K.; Anthony, J. E.; Risko, C. Theory-Driven Insight into the Crystal Packing of Trialkylsilylethynyl Pentacenes. Chem. Mater. 2017, 29 (6), 2502−2512. (8) Curtis, M. D.; Cao, J.; Kampf, J. W. Solid-State Packing of Conjugated Oligomers: From π-Stacks to the Herringbone Structure. J. Am. Chem. Soc. 2004, 126 (13), 4318−4328. 5455



Article

(49) Park, S. S.; Hontz, E. R.; Sun, L.; Hendon, C. H.; Walsh, A.; Van Voorhis, T.; Dincă, M. Cation-Dependent Intrinsic Electrical Conductivity in Isostructural Tetrathiafulvalene-Based Microporous Metal−Organic Frameworks. J. Am. Chem. Soc. 2015, 137 (5), 1774− 1777. (50) Lifshits, L. M.; Noll, B. C.; Klosterman, J. K. A supramolecular approach for designing emissive solid-state carbazole arrays. Chem. Commun. 2015, 51, 11603−11606. (51) Birks, J. B. Photophysics of Aromatic Molecules; Wiley Monographs in Chemical Physics; Wiley-Interscience: London, NY, 1970. (52) Bouas-Laurent, H.; Desvergne, J.-P.; Castellan, A.; Lapouyade, R. Photodimerization of anthracenes in fluid solution: structural aspects. Chem. Soc. Rev. 2000, 29 (1), 43−55. (53) Bouas-Laurent, H.; Desvergne, J.-P.; Castellan, A.; Lapouyade, R. Photodimerization of anthracenes in fluid solutions: (part 2) mechanistic aspects of the photocycloaddition and of the photochemical and thermal cleavage. Chem. Soc. Rev. 2001, 30 (4), 248−263. (54) Yoshizawa, M.; Klosterman, J. K. Molecular architectures of multi-anthracene assemblies. Chem. Soc. Rev. 2014, 43, 1885−1898. (55) Rubio-Pons, Ò .; Serrano-Andrés, L.; Merchán, M. A Theoretical Insight into the Photophysics of Acridine. J. Phys. Chem. A 2001, 105 (42), 9664−9673. (56) Mei, X.; Wolf, C. Formation of New Polymorphs of Acridine Using Dicarboxylic Acids as Crystallization Templates in Solution. Cryst. Growth Des. 2004, 4 (6), 1099−1103. (57) Williams, J. O.; Clarke, B. P. Acridine: an investigation of its molecular and crystalline photophysical behaviour. J. Chem. Soc., Faraday Trans. 1 1977, 73 (0), 514. (58) Lowde, R. D.; Phillips, D. C.; Wood, R. G. The crystallography of acridine. I. Acta Crystallogr. 1953, 6 (6), 553−556. (59) Desiraju, G. R.; Gavezzotti, A. Crystal structures of polynuclear aromatic hydrocarbons. Classification, rationalization and prediction from molecular structure. Acta Crystallogr., Sect. B: Struct. Sci. 1989, 45 (5), 473−482. (60) Lifshits, L. M.; Budkina, D. S.; Singh, V.; Matveev, S. M.; Tarnovsky, A. N.; Klosterman, J. K. Solution-State Photophysics of NCarbazolyl Benzoate Esters: Dual Emission and Order of States in Twisted Push-Pull Chromophores. Phys. Chem. Chem. Phys. 2016, 18, 27671−27683. (61) Tsuruoka, T.; Furukawa, S.; Takashima, Y.; Yoshida, K.; Isoda, S.; Kitagawa, S. Nanoporous Nanorods Fabricated by Coordination Modulation and Oriented Attachment Growth. Angew. Chem., Int. Ed. 2009, 48 (26), 4739−4743. (62) Abourahma, H.; Bodwell, G. J.; Lu, J.; Moulton, B.; Pottie, I. R.; Walsh, R. B.; Zaworotko, M. J. Coordination Polymers from Calixarene-Like [Cu2(Dicarboxylate)2]4 Building Blocks: Structural Diversity via Atropisomerism. Cryst. Growth Des. 2003, 3 (4), 513− 519. (63) Eddaoudi, M.; Kim, J.; Vodak, D.; Sudik, A.; Wachter, J.; O’Keeffe, M.; Yaghi, O. M. Geometric requirements and examples of important structures in the assembly of square building blocks. Proc. Natl. Acad. Sci. U. S. A. 2002, 99 (8), 4900−4904. (64) Zhang, Z.; Wojtas, L.; Zaworotko, M. J. Consequences of Partial Flexibility in 1,3-Benzenedicarboxylate Linkers: Kagomé Lattice and NbO Supramolecular Isomers from Complexation of a Bulky 1,3Benzenedicarboxylate to Cu(II) Paddlewheel Moieties. Cryst. Growth Des. 2011, 11 (5), 1441−1445. (65) Moulton, B.; Abourahma, H.; Bradner, M. W.; Lu, J.; McManus, G. J.; Zaworotko, M. J. A new 65.8 topology and a distorted 65.8 CdSO4 topology: two new supramolecular isomers of [M2(bdc)2(L)2]n coordination polymers. Supporting Information available: schematic illustrations of some common 4-connected 3D networks. See http:// www.rsc.org/suppdata/cc/b3/b301221b/. Chem. Commun. 2003, No. 12, 1342 DOI: 10.1039/b301221b. (66) Wheeler, S. E. Understanding Substituent Effects in Noncovalent Interactions Involving Aromatic Rings. Acc. Chem. Res. 2013, 46 (4), 1029−1038.

(31) Zhang, T.; Lin, W. Metal−organic frameworks for artificial photosynthesis and photocatalysis. Chem. Soc. Rev. 2014, 43 (16), 5982−5993. (32) Kent, C. A.; Mehl, B. P.; Ma, L.; Papanikolas, J. M.; Meyer, T. J.; Lin, W. Energy Transfer Dynamics in Metal−Organic Frameworks. J. Am. Chem. Soc. 2010, 132 (37), 12767−12769. (33) Wang, C.; Xie, Z.; deKrafft, K. E.; Lin, W. Doping Metal− Organic Frameworks for Water Oxidation, Carbon Dioxide Reduction, and Organic Photocatalysis. J. Am. Chem. Soc. 2011, 133 (34), 13445− 13454. (34) Kent, C. A.; Liu, D.; Ma, L.; Papanikolas, J. M.; Meyer, T. J.; Lin, W. Light Harvesting in Microscale Metal−Organic Frameworks by Energy Migration and Interfacial Electron Transfer Quenching. J. Am. Chem. Soc. 2011, 133 (33), 12940−12943. (35) Kent, C. A.; Liu, D.; Ito, A.; Zhang, T.; Brennaman, M. K.; Meyer, T. J.; Lin, W. Rapid energy transfer in non-porous metal− organic frameworks with caged Ru(bpy)32+ chromophores: oxygen trapping and luminescence quenching. J. Mater. Chem. A 2013, 1 (47), 14982. (36) Lin, J.; Hu, X.; Zhang, P.; Van Rynbach, A.; Beratan, D. N.; Kent, C. A.; Mehl, B. P.; Papanikolas, J. M.; Meyer, T. J.; Lin, W.; et al. Triplet Excitation Energy Dynamics in Metal−Organic Frameworks. J. Phys. Chem. C 2013, 117 (43), 22250−22259. (37) Whittington, C. L.; Wojtas, L.; Larsen, R. W. Ruthenium(II) Tris( 2,2′-bipyridine)-Templated Zinc(II ) 1,3,5-Tris(4carboxyphenyl)benzene Metal Organic Frameworks: Structural Characterization and Photophysical Properties. Inorg. Chem. 2014, 53 (1), 160−166. (38) Maza, W. A.; Morris, A. J. Photophysical Characterization of a Ruthenium(II) Tris(2,2′-bipyridine)-Doped Zirconium UiO-67 Metal−Organic Framework. J. Phys. Chem. C 2014, 118 (17), 8803− 8817. (39) Gao, W.-Y.; Chrzanowski, M.; Ma, S. Metal−metalloporphyrin frameworks: a resurging class of functional materials. Chem. Soc. Rev. 2014, 43, 5841−5866. (40) Fateeva, A.; Chater, P. A.; Ireland, C. P.; Tahir, A. A.; Khimyak, Y. Z.; Wiper, P. V.; Darwent, J. R.; Rosseinsky, M. J. A Water-Stable Porphyrin-Based Metal-Organic Framework Active for Visible-Light Photocatalysis. Angew. Chem., Int. Ed. 2012, 51 (30), 7440−7444. (41) Lee, C. Y.; Farha, O. K.; Hong, B. J.; Sarjeant, A. A.; Nguyen, S. T.; Hupp, J. T. Light-Harvesting Metal−Organic Frameworks (MOFs): Efficient Strut-to-Strut Energy Transfer in Bodipy and Porphyrin-Based MOFs. J. Am. Chem. Soc. 2011, 133 (40), 15858− 15861. (42) Park, H. J.; So, M. C.; Gosztola, D.; Wiederrecht, G. P.; Emery, J. D.; Martinson, A. B. F.; Er, S.; Wilmer, C. E.; Vermeulen, N. A.; Aspuru-Guzik, A.; et al. Layer-by-Layer Assembled Films of Perylene Diimide- and Squaraine-Containing Metal−Organic Framework-like Materials: Solar Energy Capture and Directional Energy Transfer. ACS Appl. Mater. Interfaces 2016, 8 (38), 24983−24988. (43) Zhang, Q.; Zhang, C.; Cao, L.; Wang, Z.; An, B.; Lin, Z.; Huang, R.; Zhang, Z.; Wang, C.; Lin, W. Förster Energy Transport in Metal− Organic Frameworks Is Beyond Step-by-Step Hopping. J. Am. Chem. Soc. 2016, 138 (16), 5308−5315. (44) Maza, W. A.; Padilla, R.; Morris, A. J. Concentration Dependent Dimensionality of Resonance Energy Transfer in a Postsynthetically Doped Morphologically Homologous Analogue of UiO-67 MOF with a Ruthenium(II) Polypyridyl Complex. J. Am. Chem. Soc. 2015, 137 (25), 8161−8168. (45) Davydov, A. S.; Dresner, S. Theory of Molecular Excitons; Springer Science+Business Media, LLC: Berlin, 2014. (46) May, V.; Kühn, O. Charge and Energy Transfer Dynamics in Molecular Systems, 3rd ed.; Wiley-VCH: Weinheim, 2011. (47) Aragó, J.; Troisi, A. Regimes of Exciton Transport in Molecular Crystals in the Presence of Dynamic Disorder. Adv. Funct. Mater. 2016, 26 (14), 2316−2325. (48) Sun, L.; Campbell, M. G.; Dincă, M. Electrically Conductive Porous Metal-Organic Frameworks. Angew. Chem., Int. Ed. 2016, 55 (11), 3566−3579. 5456



Article

(67) Wheeler, S. E.; Houk, K. N. Through-Space Effects of Substituents Dominate Molecular Electrostatic Potentials of Substituted Arenes. J. Chem. Theory Comput. 2009, 5 (9), 2301−2312. (68) Scudder, M. L.; Goodwin, H. A.; Dance, I. G. Crystal supramolecular motifs: two-dimensional grids of terpy embraces in [ML2]z complexes (L = terpy or aromatic N3-tridentate ligand). New J. Chem. 1999, 23 (7), 695−705. (69) McMurtrie, J.; Dance, I. Engineering grids of metal complexes: development of the 2D M(terpy)2 embrace motif in crystals. CrystEngComm 2005, 7 (35), 216.

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