Separation and In Situ Cocrystallization of C-Ethylresorcin [6] arenes

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Separation and in-situ cocrystallization of Cethylresorcin[6]arenes with 1-(2-pyridylazo)-2-naphthol Shan Jiang, Rahul S. Patil, Charles L. Barnes, and Jerry L. Atwood Cryst. Growth Des., Just Accepted Manuscript • DOI: 10.1021/acs.cgd.7b00172 • Publication Date (Web): 07 Apr 2017 Downloaded from http://pubs.acs.org on April 11, 2017

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Crystal Growth & Design

Separation and in-situ cocrystallization of Cethylresorcin[6]arenes with 1-(2-pyridylazo)-2-naphthol Shan Jiang,a Rahul S. Patil,a Charles L. Barnes,a and Jerry L. Atwooda* a

Department of Chemistry, University of Missouri-Columbia, 601 South College Avenue, Columbia, Missouri 65211, United States

Abstract Macrocyclic compounds are useful in variety of application such as

gas

sorption/separation as a result of their unique molecular shape and ease of synthesis. In particular, one pot synthesis of conventional resorcin[n]arenes (n=4) made resorcin[4]arenes popular for development of novel framework materials. However, synthesis of higher resorcin[n]arenes (n=5, 6) possesses difficulty in separation of a particular form from mixture of isomers and/or oligomers. This difficulty in the synthesis limits use of higher resorcin[n]arene for post synthetic applications. Here, we report separation and in situ construction of novel cocrystals

of

C-ethylresorcin[6]arene

separated

from

its

tetrameric

counterpart,

C-

ethylresorcin[4]arene. Structural features of three novel cocrystals of C-ethylresorcin[6]arene with 1-(2-pyridylazo)-2-naphthol in methanol, ethanol, and acetonitrile are discussed herein as well. Introduction In recent years, synthesis of organic macrocyclic compounds has gathered attention of a scientific community because of their lucrative applications in field of gas sorption/separation,1-2

ACS Paragon Plus Environment


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catalysis,3-4 drug delivery,5-6 and nanotechnology.7-8 A class of organic macrocyclic compounds includes calixarenes, pillarnenes, cucurbiurils, and cyclodextrines. A subclass of calixarenes, resorcin[n]arenes

is

particularly

useful

in

molecular

recognition,9-10

catalysis,11-12

electrochemistry,13-14 and nanochemistry.15-16 Tetrameric resorcin[4]arenes (4-RsC) have bowl shape supported with four resorcinol bridged through methylene group. Thus, an upper layer of this bowl shaped macrocycle is decorated with eight hydroxyl groups while lower has alkyl tail attached to the bridging methylene group (Scheme 1). These unique structural features of 4-RsC are responsible for variety of framework architectures ranging from bilayer arrangement,17 dimeric capsules,18 to hexameric hydrogen-bonded capsules19 in solid state. However, higher homologues of resorcin[n]arenes (n>4) have not been explored much for construction of novel framework materials since synthesis and separation process of a particular form (n=5, 6) from the mixtures of resorcin[n]arenes is difficult.20-21 Typically, resorcin[n]arenes are synthesized from acid catalyzed condensation reaction of resorcinol with aldehyde.22-23 This condensation reaction produces thermodynamically stable tetrameric resorcin[4]arenes, however, other stereoisomers and oligomers are also formed in minor proportions.23-24

Sherman et al and

Konishi et al reported synthesis of larger resorcin[6]arenes from 2-methylresorcinol, however, they faced difficulty in the separation of resorcin[6]arenes without functionalization and purification.15, 20 An experimental work from Sherman et al showed it is easier to functionalize and purify the reaction mixture than isolation of different resorcin[n]arenes product from the mixture. Thus, isolation of particular resorcin[n]arene remains a key difficulty in the use of higher resorcin[n]arenes (n>4) in the construction of frameworks based on resorcinarenes. Here, we applied a cocrystallization approach for separation of c-ethylresorcin[6]arene (6-RsC2) from c-ethylresorcin[4]arene (4-RsC2) and simultaneously constructed cocrystalline


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framework of 6-RsC2 with organic components (Scheme 1). The process of cocrystallization is supramolecular self-assembly in nature, where all component molecules arrange themselves spontaneously via no-covalent interactions.25 Organic component used for cocrystallition with 6RsC2 is 1-(2-pyridylazo)-2 naphthol (PAN) (Scheme 1), which is also an indicator used to determine the presence of specific metals, such as copper, zinc and nickle.26-27 Atwood et al previously synthesized cocrystals from PAN and c-alkylpyrogallol[4]arenes (PgCs) with different C-alkyl chain lengths to study intermolecular interactions between components of cocrystals.28 Resorcin[4]arene and pyrogallol[4]arene have similar molecular structures, with only variation of number of hydroxyl groups on the upper rim of bowl shaped macrocycles.29-30 Thus, a typical acid catalyzed condensation reaction was followed for synthesis of mixture of 6RsC2 and 4-RsC2, and a crude mixture was then used for cocrystallization with PAN. Crystal structures of three novel cocrystals obtained from different solvents (methanol, ethanol, and acetonitrile) are explained herein as well.



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Scheme 1: Components of cocrystallization. Result and discussion Crude product obtained from acid catalyzed condensation reaction between resorcinol and propionaldehyde consists of mixture of 4-RsC2 and 6-RsC2. Presence of both 4-RsC2 and 6RsC2 is confirmed through 1H NMR spectroscopy analysis of crude product (Figure S1). A triplet at 4.196 ppm in 1H NMR spectrum of crude product in d-methanol corresponds to hydrogen on bridged methylene group of 4-RsC2 (Figure S1). However, a similar triplet at 4.349 ppm in same spectrum is corresponds to hydrogen of bridged methylene group of 6-RsC2 (Figure S1). Thus, as-synthesized dried crude product is used for cocrystallization with PAN in methanol, ethanol, and acetonitrile separately (Detailed procedure of cocrystallization in ESI). Cocrystallization experiment in methanol, ethanol and acetonitrile resulted into single crystals suitable for single crystal X-ray diffraction. Crystal structure of 1[(6-RsC2) 3(PAN)


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3(methanol)] has 6-RsC2 macrocycle in r-trans-cis-trans-cis–trans orientation of ethylene group form bridged carbon. An asymmetric unit of 1 consists of 6-RsC2 molecule, three PAN molecules and three methanol molecules (Figure S2). Asymmetric unit of 1 doesn’t contain 4RsC2 since 4-RsC2 remains in the mother liquor after co-crystallization. 6-RsC2 exhibits four intramolecular O-H···O (2.80 Å, 2.81 Å, 2.83 Å, and 2.93 Å) hydrogen bonds among the hydroxyl groups of adjacent resorcinol rings (Figure S3). These intramolecular hydrogen bonds are responsible for holding the six resorcinol rings together in r-trans-cis-trans-cis–trans oriented conformer. A parent macrocycle forms O-H···O (2.60 Å - 2.63 Å) hydrogen bonds with two methanol molecules through resorcinol hydroxyl group placed on opposite ends of 6-RsC2 (Figure 1A). A Parent macrocycle also form four hydrogen bonds with PAN molecules placed on opposite sides of 6-RsC2 (Figure 1A). A hydroxyl group on both PAN molecules form O-H···O (2.72 Å - 2.75Å) hydrogen bond with two hydroxyl groups of 6-RsC2 and a pyridyl group on both PAN molecules also form O-H···N (2.87 Å - 2.90 Å) hydrogen bonds with two hydroxyl group of 6-RsC2 (Figure 1A). A parent 6-RsC2 macrocycle also form O-H···O (2.78 Å) hydrogen bonds with two 6-RsC macrocycle placed on opposite sides (Figure 1A). These intermolecular hydrogen bonding interactions lead to stacking arrangement of 6-RsC2 along [1 0 1] crystallographic axis in an extended crystal structure of 1. If viewed along crystallographic [1 0 0] axis, these stacking of 6-RsC2 reveals wavelike arrangement where PAN molecules occupy space between two constructive waves (Figure 1B). Two PAN molecules interact with partial cavity of 6-RsC2 with CH-π interaction between hydrogen from napthol rings of PAN and πelectron cloud formed from two resorcinol (Figure 1A). Overall, a parent 6-RsC2 interact with two adjacent 6-RsC2, two PAN molecules, and two methanol molecules through hydrogen binding interaction and two PAN molecules with comparatively weak CH-π interaction.



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Figure 1. A] Intermolecular hydrogen bonding interaction of parent 6-RsC2 with component of cocrystal in 1. B] Wave-like arrangement of stacks of 6-RsC2 and placement of PAN between these stacks (Color codes: red-oxygen, gray-carbon, blue-nitrogen; hydrogen atoms are removed for clarity). An asymmetric unit of crystal structure 2 [(6-RsC2) 3(PAN) 2(Ethanol)] consists of a 6RsC2, three PAN molecules, and two ethanol molecules (Figure S4). However, similar to 1, asymmetric unit of 2 doesn’t have any 4-RsC2 and thus 4-RsC2 remains in the mother liquor. 6RsC2 macrocycle also has four intramolecular O-H···O (2.78 Å, 2.80 Å, 2.83 Å, and 2.89 Å) hydrogen bonds among the resorcinol hydroxyl groups (Figure S5). A parent 6-RsC2 in 2 also forms four hydrogen bonds with two PAN molecules placed on opposite sides of 6-RsC2 (Figure 2). A pyridyl group of two PAN molecules form O-H···N (2.87 Å - 2.88 Å) hydrogen bonds with two hydroxyl groups of 6-RsC2. Hydroxyl groups on both PAN molecules also form O-H···O (2.71 Å - 2.72 Å) hydrogen bonds with hydroxyl groups of 6-RsC2 (Figure 2). Two ethanol molecules also form O-H···O (2.62 Å -2.64 Å) hydrogen bonds with hydroxyl groups of 6-RsC2 placed on the opposite sides of parent 6-RsC2 (Figure 2). Two PAN molecules also interact with


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two oppositely placed partial cavities of 6-RsC2 via weak CH-π interaction. A parent 6-RsC2 in 2 also forms O-H···O (2.80 Å) hydrogen bonds with two adjacent 6-RsC2 macrocycle placed diagonally opposite side of parent 6-RsC2 (Figure 2). These intermolecular hydrogen bonds lead to the formation of stacking arrangement of 6-RsC2 along [1 0 0] crystallographic axis in the extended crystal structure of 2 (Figure S6). Thus, similar to 1, a parent 6-RsC2 in 2 also interacts with two adjacent macrocycles, four PAN molecules, and two ethanol molecules through hydrogen bonding and/or CH-π interactions.

Figure 2. Intermolecular hydrogen bonding interaction of parent 6-RsC2 with component of cocrystal 2 (Color codes: red-oxygen, gray-carbon, blue-nitrogen; hydrogen atoms are removed for clarity).



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Crystal structure of 3 [(6-RsC2) 2(PAN) 2(Acetonitrile)] has an asymmetric unit which consists of half of 6-RsC2, one PAN molecule and two acetonitrile molecules. Similar to 1, and 2, 6-RsC2 molecule in 3 also has four intramolecular O-H···O (2.72 Å - 2.79 Å) interactions among the hydroxyl groups of resorcinol (Figure S7). Four hydroxyl groups on 6-RsC2 form four hydrogen bonds with two PAN molecules placed diagonally opposite sides of a 6-RsC2. These intermolecular hydrogen bonds involve O-H···N (2.84Å) and O-H···O (2.75Å) with pyridyl and hydroxyl functional groups of PAN respectively (Figure 3A). A parent 6-RsC2 forms eight O-H···O (2.69 Å - 2.78Å) hydrogen bonds with four adjacent macrocycles and thus, exhibits continuous 2D array of hydrogen bonding interaction in the extended crystal structure of 3 (Figure 3B). This intermolecular hydrogen bonding interactions lead formation of stacking arrangement of 6-RsC2 in extended crystal structure along [1 0 0] crystallographic axis (Figure 3C). The space between stacks of 6-RsC2 is occupied by a stack of PAN molecules (Figure 3C).


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Figure 3. A] Intermolecular hydrogen bonding interaction of 6-RsC2 with PAN and acetonitrile molecules. B] Intermolecular hydrogen bonding interaction of parent 6-RsC2 with adjacent 6RsC2. C] Alternate arrangement of 6-RsC2 stacks and PAN molecules (Color codes: red-oxygen, gray-carbon, blue-nitrogen; hydrogen atoms are removed for clarity). All three crystal structures exhibit r-trans-cis-trans-cis-trans conformer of 6-RsC2 as a result of four intramolecular O-H···O hydrogen bonds between the hydroxyl groups. This particular conformer exhibits two partially opened cavities which host two guest PAN molecules. This host–guest interaction is supported with weak CH-π interactions between napthalic hydrogen of PAN and π electron cloud of resorcinol rings. Four extra hydroxyl groups on the 6-



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RsC2 compared to 4-RsC2 help to form more hydrogen bonds with components of cocrystallization since all hydroxyl groups of 6-RsC2 are involved in either intra or intermolecular hydrogen bonds. Thus, hydrogen bonds and CH-π interactions induce formation of more closely packed cocrystal of 6-RsC2 with PAN and solvent molecules leaving 4-RsC2 in mother liquor. Powder crystal X-ray diffraction (PXRD) patterns of all three bulk cocrystals match well with PXRD pattern deduced from SC-XRD (Figure S8, S9, and S10). This reveals the uniformity of cocrystals obtained from these experiments. 4-RsC2 can easily be recovered from mother liquor by evaporating solvent under vacuum. Conclusion Separation and simultaneous construction of novel cocrystal from resorcin[6]arenes and PAN in three different solvents are explained here. Formation of corystals is facilitated by intermolecular hydrogen bonding interactions of hydroxyl groups of 6-RsC2 with hydroxyl and pyridyl functional group of PAN molecules. A parent 6-RsC2 also forms hydrogen bonding interactions with neighboring 6-RsC2 macrocycles and solvent molecules. Thus, multiple hydrogen bonds resulted in formation of cocrystals between 6-RsC2 and PAN leaving 4-RsC2 in the mother liquor. Robustness of separation and in situ formation of cocrystals is proved in three different solvents systems. The investigation of separating other macrocycle compounds via cocrystallization could be carried out in the future. AUTHOR INFORMATION Corresponding Author *Prof. Jerry L. Atwood, Email: [email protected] Supporting Information


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The Supporting Information is available free of charge on the ACS Publications website: Synthetic procedures, NMR, PXRD, and single-crystal XRD data. Notes The authors declare no competing financial interest. Accession Codes CCDC 1529997− 1529999 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. References (1) Atwood, J. L.; Barbour, L. J.; Jerga, A. J. Am. Chem. Soc. 2002, 124, 2122. (2) Patil, R. S.; Banerjee, D.; Zhang, C.; Thallapally, P. K.; Atwood, J. L. Angew. Chem., Int. Ed. 2016, 55, 4523. (3) Guo, Y.; Solovyov, A.; Grosso-Giordano, N. A.; Hwang, S.-J.; Katz, A. ACS Catalysis 2016, 6 , 7760. (4) Deraedt, C.; Astruc, D. Coord. Chem. Rev. 2016, 324, 106. (5) Xu, M.; Zhang, Z.; Xu, J.; Yang, X.; He, K.; Yu, H.; Jiang, S. 2016-10372876,106008531, 20160530., 2016. (6) Hassanzadeh, K.; Akhtari, K.; Esmaeili, S. S.; Vaziri, A.; Zamani, H.; Maghsoodi, M.; Noori, S.; Moradi, A.; Hamidi, P. J. Theor. Comput. Chem. 2016, 15, 1650056. (7) Stoffelen, C.; Huskens, J. Small 2016, 12, 96. (8) Karoyo, A. H.; Wilson, L. D. Nanomaterials 2015, 5, 981. (9) Arduini, A.; Casnati, A.; Dalcanale, E.; Pochini, A.; Ugozzoli, F.; Ungaro, R. NATO ASI Series, Series C: J. Math. Phys. Sci. 1999, 527 ,67. (10) Pinalli, R.; Brancatelli, G.; Pedrini, A.; Menozzi, D.; Hernandez, D.; Ballester, P.; Geremia, S.; Dalcanale, E. J. Am. Chem. Soc. 2016, 138, 8569. (11) Gangemi, C. M. A.; Pappalardo, A.; Trusso Sfrazzetto, G. RSC Adv. 2015, 5 (64), 51919. (12) Semeril, D.; Matt, D. Coord. Chem. Rev. 2014, 279, 58. (13) Wang, F.; Wu, Y.; Ma, H.; Li, B.; Ye, B. J. Electrochem. Soc. 2016, 163, H367. (14) Zhou, J.; Chen, M.; Diao, G. J Mater Chem A Mater Energy Sustain, 2013, 1, 2278. (15) Konishi, H.; Ohata, K.; Morikawa, O.; Kobayashi, K. Chem. Commun. 1995, 3, 309. (16) Wirtheim, E.; Avram, L.; Cohen, Y. Tetrahedron 2009, 65, 7268. (17) Ma, B.-Q.; Coppens, P. Chem. Commun. 2002, 5, 424. (18) Patil, R. S.; Mossine, A. V.; Kumari, H.; Barnes, C. L.; Atwood, J. L. Cryst. Growth Des. 2014, 14 , 5212. (19) MacGillivray, L. R.; Atwood, J. L. Nature 1997, 389, 469. (20) Naumann, C.; Roman, E.; Peinador, C.; Ren, T.; Patrick, B. O.; Kaifer, A. E.; Sherman, J. C. Chem. – Eur. J. 2001, 7 , 1637.



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(21) Della Sala, P.; Gaeta, C.; Navarra, W.; Talotta, C.; De Rosa, M.; Brancatelli, G.; Geremia, S.; Capitelli, F.; Neri, P. J. Org. Chem. 2016, 81, 5726. (22) Cram, D. J.; Karbach, S.; Kim, H. E.; Knobler, C. B.; Maverick, E. F.; Ericson, J. L.; Helgeson, R. C. J. Am. Chem. Soc. 1988, 110 , 2229. (23) Tunstad, L. M.; Tucker, J. A.; Dalcanale, E.; Weiser, J.; Bryant, J. A.; Sherman, J. C.; Helgeson, R. C.; Knobler, C. B.; Cram, D. J. J. Org. Chem. 1989, 54, 1305. (24) Timmerman, P.; Verboom, W.; Reinhoudt, D. N. Tetrahedron 1996, 52 , 2663. (25) Wood, P. A.; Feeder, N.; Furlow, M.; Galek, P. T. A.; Groom, C. R.; Pidcock, E. CrystEngComm 2014, 16, 5839. (26) Arvand, M., Abolghasemi, S. & Zanjanchi, J. Anal. Chem. 2007,62,342. (27) Tarighat, M. A., & Afkhami, Abbas. J. Braz. Chem. Soc. 2012, 2, 1312. (28) Pfeiffer, C. R.; Fowler, D. A.; Teat, S.; Atwood, J. L. CrystEngComm 2014, 16, 10760. (29) Patil, R. S.; Drachnik, A. M.; Kumari, H.; Barnes, C. L.; Deakyne, C. A.; Atwood, J. L. Cryst.. Growth Des. 2015, 15, 2781. (30) Patil, R. S.; Kumari, H.; Barnes, C. L.; Atwood, J. L. Chem. Commun. 2015, 51, 2304.


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For Table of Contents Use Only:

Separation and in-situ cocrystallization of Cethylresorcin[6]arenes with 1-(2-pyridylazo)-2-naphthol Shan Jiang, Rahul S. Patil, Charles L. Barnes, and Jerry L. Atwood

Synopsis: Three new cocrystals based on C-ethylresorcin[6]arene and 1-(2-pyridylazo)-2 naphthol (PAN) are discussed here. The cocrystals were synthesized from a mixture of C-ethylresorcin[4]arene and C-ethylresorcin[6]arene with PAN molecules in different solvents, and PAN molecules show self-recognition towards C-ethylresorcin[6[arene, which results in the separation of Cethylresorcin[6[arene from the mixture.



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Scheme 1: Components of cocrystallization 309x227mm (96 x 96 DPI)


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Figure 1. A] Intermolecular hydrogen bonding interaction of parent 6-RsC2 with component of cocrystal in 1. B] Wave-like arrangement of stacks of 6-RsC2 and placement of PAN between these stacks (Color codes: Red-Oxygen, Gray-Carbon, Blue-Nitrogen; hydrogen atoms are removed for clarity). 70x31mm (300 x 300 DPI)



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Figure 2. Intermolecular hydrogen bonding interaction of parent 6-RsC2 with component of cocrystal 2 (Color codes: Red-Oxygen, Gray-Carbon, Blue-Nitrogen; hydrogen atoms are removed for clarity). 128x106mm (150 x 148 DPI)


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Figure 3. A] Intermolecular hydrogen bonding interaction of 6-RsC2 with PAN and acetonitrile molecules. B] Intermolecular hydrogen bonding interaction of parent 6-RsC2 with adjacent 6-RsC2. C] Alternate arrangement of 6-RsC2 stacks and PAN molecules (Color codes: Red-Oxygen, Gray-Carbon, Blue-Nitrogen; hydrogen atoms are removed for clarity). 57x55mm (300 x 300 DPI)


Separation and In Situ Cocrystallization of C-Ethylresorcin [6] arenes

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