By varying the halogen-bond-donor molecule, 11 new halogen-bonding cocrystals involving thiourea or 1,3-dimethylthiourea were obtained, namely, 1,3-dimethylthiourea–1,2-diiodo-3,4,5,6-tetrafluorobenzene (1/1), C 6 F 4 I 2 ·C 3 H 8 N 2 S, 1 , thiourea–1,3-diiodo-2,4,5,6-tetrafluorobenzene (1/1), C 6 F 4 I 2 ·CH 4 N 2 S, 2 , 1,3-dimethylthiourea–1,3-diiodo-2,4,5,6-tetrafluorobenzene (1/1), C 6 F 4 I 2 ·C 3 H 8 N 2 S, 3 , 1,3-dimethylthiourea–1,3-diiodo-2,4,5,6-tetrafluorobenzene–methanol (1/1/1), C 6 F 4 I 2 ·C 3 H 8 N 2 S·CH 4 O, 4 , 1,3-dimethylthiourea–1,3-diiodo-2,4,5,6-tetrafluorobenzene–ethanol (1/1/1), C 6 F 4 I 2 ·C 3 H 8 N 2 S·C 2 H 6 O, 5 , 1,3-dimethylthiourea–1,4-diiodo-2,3,5,6-tetrafluorobenzene (1/1), C 6 F 4 I 2 ·C 3 H 8 N 2 S, 6 , 1,3-dimethylthiourea–1,3,5-trifluoro-2,4,6-triiodobenzene (1/1), C 6 F 3 I 3 ·C 3 H 8 N 2 S, 7 , 1,3-dimethylthiourea–1,1,2,2-tetraiodoethene (1/1), C 6 H 16 N 4 S 2 ·C 2 I 4 , 8 , [(dimethylamino)methylidene](1,2,2-triiodoethenyl)sulfonium iodide–1,1,2,2-tetraiodoethene–acetone (1/1/1), C 5 H 8 I 3 N 2 S + ·I − ·C 3 H 6 O·C 2 I 4 , 9 , 2-amino-4-methyl-1,3-thiazol-3-ium iodide–1,1,2,2-tetraiodoethene (2/3), 2C 4 H 7 N 2 S + ·2I − ·3C 2 I 4 , 10 , and 4,4-dimethyl-4 H -1,3,5-thiadiazine-3,5-diium diiodide–1,1,2,2-tetraiodoethene (2/3), 2C 5 H 12 N 4 S 2+ ·4I − ·3C 2 I 4 , 11 . When utilizing the common halogen-bond-donor molecules 1,2-, 1,3-, and 1,4-diiodotetrafluorobenzene, as well as 1,3,5-trifluoro-2,4,6-triiodobenzene, bifurcated I...S...I interactions were observed, resulting in the formation of isolated rings, chains, and sheets. Tetraiodoethylene (TIE) provided I...S...I cocrystals as well, but further yielded a sulfonium-containing product through the reaction of the S atom with TIE. This particular sulfonium motif is the first of its kind to be structurally characterized, and is stabilized in the solid state through a three-dimensional I...I halogen-bonding network. Thiourea reacted with acetone in the presence of TIE to provide two novel heterocyclic products, again stabilized in the solid state through I...I halogen bonding.
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Ditopic halogen bonding with bipyrimidines and activated pyrimidines
The potential of pyrimidines to serve as ditopic halogen-bond acceptors is explored. The halogen-bonded cocrystals formed from solutions of either 5,5′-bipyrimidine (C 8 H 6 N 4 ) or 1,2-bis(pyrimidin-5-yl)ethyne (C 10 H 6 N 4 ) and 2 molar equivalents of 1,3-diiodotetrafluorobenzene (C 6 F 4 I 2 ) have a 1:1 composition. Each pyrimidine moiety acts as a single halogen-bond acceptor and the bipyrimidines act as ditopic halogen-bond acceptors. In contrast, the activated pyrimidines 2- and 5-{[4-(dimethylamino)phenyl]ethynyl}pyrimidine (C 14 H 13 N 3 ) are ditopic halogen-bond acceptors, and 1:1 halogen-bonded cocrystals are formed from 1:1 mixtures of each of the activated pyrimidines and either 1,2- or 1,3-diiodotetrafluorobenzene. A 1:1 cocrystal was also formed between 2-{[4-(dimethylamino)phenyl]ethynyl}pyrimidine and 1,4-diiodotetrafluorobenzene, while a 2:1 cocrystal was formed between 5-{[4-(dimethylamino)phenyl]ethynyl}pyrimidine and 1,4-diiodotetrafluorobenzene.
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- NSF-PAR ID:
- 10184726
- Date Published:
- Journal Name:
- Acta Crystallographica Section C Structural Chemistry
- Volume:
- 76
- Issue:
- 5
- ISSN:
- 2053-2296
- Page Range / eLocation ID:
- 458 to 467
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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The ditopic halogen-bond (X-bond) donors 1,2-, 1,3-, and 1,4-diiodotetrafluorobenzene (1,2-, 1,3-, and 1,4-di-I-tFb, respectively) form binary cocrystals with the unsymmetrical ditopic X-bond acceptor trans-1-(2-pyridyl)-2-(4-pyridyl)ethylene (2,4-bpe). The components of each cocrystal (1,2-di-I-tFb)·(2,4-bpe), (1,3-di-I-tFb)·(2,4-bpe), and (1,4-di-I-tFb)·(2,4-bpe) assemble via N···I X-bonds. For (1,2-di-I-tFb)·(2,4-bpe) and (1,3-di-I-tFb)·(2,4-bpe), the X-bond donor supports the C=C bonds of 2,4-bpe to undergo a topochemical [2+2] photodimerization in the solid state: UV-irradiation of each solid resulted in stereospecific, regiospecific, and quantitative photodimerization of 2,4-bpe to the corresponding head-to-tail (ht) or head-to-head (hh) cyclobutane photoproduct, respectively.
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Utilizing the N -heterocyclic chalcogenones hexahydro-1,3-bis(2,4,6-trimethylphenyl)-2 H -1,3-diazepine-2-thione ( SDiazMesS ) and hexahydro-1,3-bis(2,4,6-trimethylphenyl)-2 H -1,3-diazepine-2-selone ( SDiazMesSe ) as halogen-bond acceptors, a total of 24 new cocrystals were prepared. The solid-state structures of the parent molecules were also determined, along with those of their acetonitrile solvates. Through the reaction of the chalcogen atom with molecular diiodine, a variety of S—I—I and Se—I—I fragments were formed, spanning a wide range of I—I bond orders. With acetone as a reaction solvent, molecular diiodine causes the oxidative addition of acetone to the chalcogen atom, resulting in new C—S, C—Se and C—C covalent bonds under mild conditions. The common halogen-bond donors, iodopentafluorobenzene, 1,2-, 1,3- and 1,4-diiodotetrafluorobenzene, 1,3,5-trifluorotriiodobenzene and tetraiodoethylene resulted in halogen-bond-driven cocrystal formation. In most cases, the analogous SDiazMesS and SDiazMesSe cocrystals are isomorphic.more » « less
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Abstract Cocrystallizations of diboronic acids [1,3‐benzenediboronic acid (1,3‐bdba), 1,4‐benzenediboronic acid (1,4‐bdba) and 4,4’‐biphenyldiboronic acid (4,4’‐bphdba)] and bipyridines [1,2‐bis(4‐pyridyl)ethylene (bpe) and 1,2‐bis(4‐pyridyl)ethane (bpeta)] generated the hydrogen‐bonded 1 : 2 cocrystals [(1,4‐bdba)(bpe)2] (1), [(1,4‐bdba)(bpeta)2] (2), [(1,3‐bdba)(bpe)2(H2O)2] (3) and [(1,3‐bdba)(bpeta)2(H2O)] (4), wherein 1,3‐bdba involved hydrated assemblies. The linear extended 4,4’‐bphdba exhibited the formation of 1 : 1 cocrystals [(4,4'‐bphdba)(bpe)] (5) and [(4,4'‐bphdba‐me)(bpeta)] (6). For 6, a hemiester was generated by an in‐situ linker transformation. Single‐crystal X‐ray diffraction revealed all structures to be sustained by B(O)−H⋅⋅⋅N, B(O)−H⋅⋅⋅O, Ow−H⋅⋅⋅O, Ow−H⋅⋅⋅N, C−H⋅⋅⋅O, C−H⋅⋅⋅N, π⋅⋅⋅π, and C−H⋅⋅⋅π interactions. The cocrystals comprise 1D, 2D, and 3D hydrogen‐bonded frameworks with components that display reactivities upon cocrystal formation and within the solids. In 1 and 3, the C=C bonds of the bpe molecules undergo a [2+2] photodimerization. UV radiation of each compound resulted in quantitative conversion of bpe into cyclobutane tpcb. The reactivity involving 1 occurred via 1D‐to‐2D single‐crystal‐to‐single‐crystal (SCSC) transformation. Our work supports the feasibility of the diboronic acids as formidable structural and reactivity building blocks for cocrystal construction.
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This study expands and combines concepts from two of our earlier studies. One study reported the complementary halogen bonding and π-π charge transfer complexation observed between isomeric electron rich 4-N,N-dimethylaminophenylethynylpyridines and the electron poor halogen bond donor, 1-(3,5-dinitrophenylethynyl)-2,3,5,6-tetrafluoro-4-iodobenzene while the second study elaborated the ditopic halogen bonding of activated pyrimidines. Leveraging our understanding on the combination of these non-covalent interactions, we describe cocrystallization featuring ditopic halogen bonding and π-stacking. Specifically, red cocrystals are formed between the ditopic electron poor halogen bond donor 1-(3,5-dinitrophenylethynyl)-2,4,6-triflouro-3,5-diiodobenzene and each of electron rich pyrimidines 2- and 5-(4-N,N-dimethyl-aminophenylethynyl)pyrimidine. The X-ray single crystal structures of these cocrystals are described in terms of halogen bonding and electron donor-acceptor π-complexation. Computations confirm that the donor-acceptor π-stacking interactions are consistently stronger than the halogen bonding interactions and that there is cooperativity between π-stacking and halogen bonding in the crystals.more » « less
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1107/S2053229620005082
