Communication pubs.acs.org/crystal
Interplay of Pyridine Substitution and Ag(I)···Ag(I) and Ag(I)···π Interactions in Templating Photochemical Solid State [2 + 2] Reactions of Unsymmetrical Olefins Containing Amides: SingleCrystal-to-Single-Crystal Transformations of Coordination Polymers Mousumi Garai,† Kousik Maji,† Vladimir V. Chernyshev,‡ and Kumar Biradha*,† †
Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, India Department of Chemistry, Moscow State University, 119992 Moscow, Russia
‡
S Supporting Information *
ABSTRACT: The unsymmetrical bispyridyl olefins containing amides (UBOs) have been synthesized to study solid state [2 + 2] photochemical reactions with or without template. The crystal structures of UBOs were determined using a powder Xray diffraction technique. The pure organic materials of UBOs were found to form head-to-head (HH)-dimers upon irradiation in accordance with their crystal structures. Further, Ag···Ag and Ag···π interactions were shown to template headto-tail (HT) photodimerization of UBOs in their onedimensional-coordination polymers in single-crystal-to-singlecrystal manner. The dimer structures were determined by single crystal X-ray and 1H NMR techniques.
T
Scheme 1. Schematic Representation for Alignments of Double Bonds via Ag···Ag nd Ag···π Interactions: (a) MPO; (b) SBO; and (c) UBO
he use of organic/inorganic templates to promote photochemical solid state [2 + 2] reactions of olefin containing substrates is becoming an attractive area of research given their facile reactivities, stereocontrol, and high yields.1−22We and others have shown earlier the importance of Ag···Ag interactions in templating head-to-head HH-dimers in pyridine-substituted olefin derivatives.23−25 We also showed that the anions play a significant role in altering the geometry of resultant products.26−29 However, the olefins considered to date are either symmetrical bispyridyl olefins (SBO) or monopyridyl olefins (MPO). The solid state [2 + 2] reactions of unsymmetrical bispyridyl olefins (UBO) containing amide group in spacers were not explored to date either with templation or without templation. In the case of SBO or MPO, the Ag···Ag interactions can template the reactions through a proper alignment of double bonds, 30−34 while Ag···π interactions misalign the double bonds (Scheme 1). Recently, we have shown one odd example in which Ag···π interactions precede over Ag···Ag interactions to template head-to-tail HTdimers of unsymmetrical olefin containing benzimidazole and pyridyl functionalities.35 These results hinted that, in principle, the UBOs can be designed such that Ag···Ag or Ag···π interactions can be used to align the double bonds to yield HTdimers. Once the main framework of the UBO (Scheme 2) is designed, the required alignments can be achieved by changing substitution on the pyridine ring and anions which may play a significant role in influencing these interactions. The UBOs 1−2 were designed to study their solid state photochemical [2 + 2] reactions in their crystals as well as their © XXXX American Chemical Society
Scheme 2. Chemical Diagrams of UBOs 1−2
Ag(I) complexes. These compounds were synthesized by the condensation reaction between corresponding acrylic acids and amino pyridines. The crystallization reactions of compounds Received: November 17, 2015 Revised: January 11, 2016
A
DOI: 10.1021/acs.cgd.5b01624 Cryst. Growth Des. XXXX, XXX, XXX−XXX
Crystal Growth & Design
Communication
were conducted in various solvents to obtain crystals suitable for single crystal X-ray diffraction. Despite several trials suitable single crystals of 1 and 2 could not be obtained for both the compounds. However, their crystal structures were obtained using their powder X-ray diffraction patterns (see Supporting Information). The powder X-ray diffraction analysis of 1 revealed that it exhibits phase changes. The structure analysis indicates that initially it forms a trihydrate, which changes its phase to form anhydrate upon exposure to fresh air. The crystal structure of trihydate suggests that the double bonds are crisscross aligned with a required distance (3.628 Å) (Figure 1a), and water
Figure 2. Illustrations for the crystal structure of 1-HH: (a) ORTEP drawing of 1-HH; (b) 1D chains via N−H···O bonds; (c) 1D chain of water molecules; (d) overall 3D network.
resulted in single crystals of {Ag(1)(CH3CN)]·(ClO4)}n (1a) and {[Ag2(1)2(CH3CN)(NO3)]NO3}n (1b), while the reactions with AgBF4 resulted in the precipitates. The complexes 1a and 1b crystallizes in P21/n and P1̅ space groups, respectively. The crystal structures differ significantly, but both contain CH3CN in the crystal lattice and Ag(I) atoms are tricoordinate. In 1a, the Ag(I) exhibits T-shape geometry as it is coordinated to two pyridine units of 1 and one acetonitrile. While 1b contains two Ag(I) atoms both coordinated to two pyridyl units each, the third coordination site are occupied by CH3CN in one case and nitrate ion in the second case. The major difference between these two structures is 1a contains zigzag polymers, while the 1b contains a macrocyle due to the difference in the conformation of 1: in 1a the pyridine groups are anti (divergent), and in 1b they are syn to each other (convergent) (Figure S29). In 1a, the chains pack such that there are infinite stacks of 1a in HT fashion. The Ag···Ag (3.400 Å) and Ag···π (4.374 Å) interactions alternate in the stacks (Figure 3a). The stacks containing Ag···Ag interactions align the double bonds in a HT-fashion with a shorter separation distance of 3.791 Å. As a result the irradiation of 1a
Figure 1. Illustrations for the crystal structure of 1: (a) criss-cross arrangement of olefin; (b) 1D helix via N−H···N hydrogen bonds; (c) parallel alignment of olefin.
molecules form hydrogen bonds with pyridine as well as amide functionalities (Figure S27). While in anhydrate, the hydrogen bonding between the pyridine N atom and amide N−H leads to the formation of a one-dimensional (1D) helix along the baxis with a pitch length of 3.9 Å. The pitch length serves as a separating distance for double bonds with a parallel alignment in a head-to-head fashion (Figure 1b,c). The powdered material of 1 was irradiated in sunlight, and the progress of the reaction was monitored by 1H NMR spectrum, which revealed the formation a head-to-head dimer (1-HH) in 100% yield in 48 h. In 1H NMR spectrum, cyclobutane peaks appeared at δ = 4.47 and 4.21 ppm with disappearance of olefin protons, and shifting of the amide proton from 10.50 ppm (monomer) to 10.06 ppm (dimer) was observed (Figure S3). The single crystals of 1-HH are obtained by recrystallization of irradiated material of 1 in MeOH-H2O (2:1, v/v) solvent system. The molecule 1-HH crystallizes in non-centrosymmetric spacegroup Pca21. The asymmetric unit is constituted by 1-HH and two water molecules. The cyclobutane ring exhibits puckered geometry with C−C−C torsion angle of 20° (Figure 2a). The dimers interact via amide-to-amide hydrogen bonds (N···O, N−H···O: 2.85 Å, 163° and 2.47 Å, 173°) with a two point recognition of AA−DD type to form 1D chains (Figure 2b). Water molecules are also found to form 1D chains via O− H···O hydrogen bonds (Figure 2c); these two types of 1D chains interlinked via (Ow−H···Npy) hydrogen bonding with pyridine N atoms to form a three-dimensional (3D) network (Figure 2d). In order to obtain a HT-dimer of 1 and also to study template effects of Ag(I) and anions, it was complexed with Ag(I) salts of ClO4−, NO3−, and BF4−. It is also of interest to see which interactions will be successful among Ag(I)···Ag(I) and Ag(I)···π in templating such a dimer. These reactions
Figure 3. Illustrations for the crystal structures of 1a and 1b: (a) alignment of double bond of 1a for [2 + 2] reaction; (b) M2L2 macrocycle with criss-cross arrangement; (c) distance of double bonds of 1b. B
DOI: 10.1021/acs.cgd.5b01624 Cryst. Growth Des. XXXX, XXX, XXX−XXX
Crystal Growth & Design
Communication
Notably, the 4-pyridine does not involve hydrogen bonding; therefore it also contains similar chains as 1. As there is a required alignment of double bonds with a distance of 3.844 Å and torsion angle 0° (Figure 5b), irradiation of a powder sample of 2 for 48 h resulted in the HH-dimer with 65% yield. The dimer was characterized by 1H NMR spectroscopy. The appearance of new signals for cyclobutane protons at δ = 4.43 and 4.21 ppm and corresponding shift in the bis-pyridyl proton signals confirm the formation of the photodimer in a HH fashion (Figure S6). The complexation reactions of 2 with Ag (I) salts of NO3−, ClO4−, and BF4− in MeOH-DCM mixture resulted in single crystals of complexes [{Ag(2)(H2O)}(NO3)]n (2a), [{Ag(2)(H2O)}(ClO4)]n (2b), and [{Ag(2)(H2O)}(BF4)]n (2c). The single crystal analyses of these complexes revealed that 2a and 2b are isostructural as both crystallized in P1̅ space group with almost identical cell parameters while 2c crystallized in P21/n space group. However, all three contain one unit each of 2, Ag(I), corresponding anions, and water molecules in the asymmetric unit. The Ag(I) adopts near triangular geometry as it coordinates one each of 3-pyridyl and 4-pyridyl moieties of 2 and a water molecule. As a result, all three complexes contain 1D coordination polymers with a linear geometry. Two of such chains, which are related by inversion, stack on each other such that the 3-pyridyl group and 4-pyridyl groups from adjacent chains have a slipped stacking with centroid-to-centroid distances (X···X) of 4.191, 4.262, and 4.284 Å in 2a−2c respectively. Further these stacks also have Ag···π interactions with a 4-pyridyl group (Ag···centroid, Ag···X: 4.118, 4.041, and 4.212 Å in 2a−2c respectively) and amide···π interactions with 3-pyridyl group (amide-N to centroid, N···X: 3.406, 3.543, and 3.516 Å in 2a−2c respectively). As a result the double bonds of 2 from adjacent chains are aligned in a required parallel orientation with a distances of 3.578, 3.614, and 3.649 Å in 2a− 2c, respectively, such that upon irradiation it should lead to the formation of HT-dimers. Interestingly, all three complexes lead to the formation HT-dimers (2a′, 2b′, and 2c′) in singlecrystal-to-single-crystal (SCSC) fashion upon irradiation for 6 h (Figure 6).
results in the formation of the HT-dimer in 60% yield. In 1b such alignment of double bonds was not observed, although the macrocylcles form dimer via Ag···Ag interactions, making this photostable (Figure 3b,c). The 1-HT dimer was separated from irradiated materials by acid−base work up, and the dimer structure was characterized by 1H NMR spectroscopy (Figure S4). Our attempts to obtain suitable single crystals of the HT-dimer failed. However, the single crystals of its cocrystals (1-HT)·(AA)3 with adipic acid (AA) from EtOH-EtOAc (2:1 v/v) solvent were successfully obtained. The crystal structure analysis confirms the HT geometry of dimer of 1 in which the cyclobutane exhibits planar geometry. The asymmetric unit is constituted by half unit of HT and one and half units of AA. The HT and one of the AA sit on an inversion center. One of the AA is involved in the formation of an acid-pyridine heterosynthon such that a 1D network is formed (Figure 4), and the other AA hydrogen bonds to amide N−H and form a 3D hydrogen bonding network (Figure S30).
Figure 4. Illustration for the crystal structure of 1-HT: 1D chain via formation of acid-pyridine heterosynthon.
The Ag···Ag interactions are templating the HT-dimer of 1 in 1a as the dimer formation occurring through inversion symmetry, and both are 3-pyridyl groups. Similar HT-dimer formation via Ag···Ag interactions was also found in the Ag(I) complex of 4-pyrdiyl derivative.36 At this point it occurred to us that a olefin containing 3-pyridyl and 4-pyridyl substitution should not contain such Ag···Ag interactions in the dimer (inversion related) due to positional mismatch. In such cases, can Ag···π interactions will take over the role of templating [2 + 2] reactions in place of Ag···Ag interactions? With that intension, the molecule 2 was prepared by the condensation of (E)-3-(pyridin-3-yl) acrylic acid with 4-aminopyridine. Similar to 1, the single crystals suitable for X-ray diffraction could not be obtained despite several trails. However, the crystal structure of it was obtained using powder X-ray diffraction. Although it is not isostructural with that of 1, it contains similar N−H···N hydrogen bonded helical chains (Figure 5a), along the b-axis with a repeat distance of 3.844 Å, in which the olefins are aligned with the HH-dimer.
Figure 6. Transformation of 1D-chains to 1D-ladder upon irradiation of complex 2a.
With the exception of 2c′, the 2a′ and 2b′ exhibited same space group with almost identical cell parameters as the crystals of their respective parents. The overall contraction of unit cell volumes was found to be 7 and 10 Å3 in 2a′ and 2b′ respectively. The a- and c-axes (a = 8.10 to 7.9 Å; c = 10.65 to 10.17 Å for 2a to 2a′; a = 8.21 to 8.16 Å; c = 10.41 to 10.26 Å for 2b to 2b′) have undergone significant contractions, while
Figure 5. Illustrations for the crystal structure of 2: (a) N−H···N hydrogen bonded helix; (b) parallel alignment of double bonds. C
DOI: 10.1021/acs.cgd.5b01624 Cryst. Growth Des. XXXX, XXX, XXX−XXX
Crystal Growth & Design
■
the b-axis exhibited expansion (8.93 to 9.42 Å for 2a to 2a′ and 9.91 to 10.13 Å for 2b to 2b′) due to the reaction. The SCSC reaction of 2c resulted in a change in the crystal system from monoclinic to triclinic and therefore the space group from P21/ n to P1.̅ Overall change in the distances of Ag···X, X···X, and N···X was observed after the reaction. The Ag···X distances increased by 0.066, 0.507, and 0.231 Å in 2a′−2c′ respectively, and X···X distances decreased by 0.248, 0.221, and 0.251 Å in 2a′−2c′ respectively, whereas the N···X distance increased by 0.12 Å in 2a′ and decreased by 0.098 and 0.051 Å in 2b′ and 2c′ respectively. The cyclobutane (CB) rings were found to be planar in all three complexes. Interestingly, the external C−C− C angles around the C-atom of CB carrying 3-pyrdine was found to be higher than those of the C atom of CB carrying amide groups. The formation of product was also confirmed by 1H NMR spectra of 2a′−2c′, which indicated the disappearance of olefin protons, a shift of N−H proton from 10.68 to 10.35 ppm, and the appearance of CB proton at 4.56 and 4.14 ppm (Figure S7). Further, the dimer was isolated by acid base workup of 2a′ and single crystals (2-HT) were obtained by recrystallizing from H2O-MeOH (1:1 v/v). The crystal structure analysis of 2-HT reveals that it crystallizes in P21/c and the asymmetric unit consists of half molecule of dimer and two water molecules (Figure 7). The CB
Communication
ASSOCIATED CONTENT
S Supporting Information *
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.cgd.5b01624 Experimental details and characterization of the compounds by 1H NMR spectra, FTIR spectra, PXRD patterns and crystallographic data and refinement (PDF) Accession Codes
CCDC 1427148−1427161 contains 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.
■
AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. Fax: +91 3222282252. Tel: +91 3222-283346. Notes
The authors declare no competing financial interest.
■
ACKNOWLEDGMENTS We gratefully acknowledge financial support from DST and DST-FIST for single crystal X-ray facility. MG thanks IIT-KGP for research fellowship.
■
REFERENCES
(1) Schmidt, G. M. J. Pure Appl. Chem. 1971, 27, 647−678. (2) Biradha, K.; Santra, R. Chem. Soc. Rev. 2013, 42, 950−967. (3) Leong, W. L.; Vittal, J. J. Chem. Rev. 2011, 111, 688−764. (4) Libri, S.; Mahler, M.; Minguez Espallargas, G. M.; Singh, D. C. N. G.; Soleimannejad, J.; Adams, H.; Burgard, M. D.; Rath, N. P.; Brunelli, M.; Brammer, L. Angew. Chem., Int. Ed. 2008, 47, 1693−1697. (5) Ramamurthy, V.; Venkatesan, K. Chem. Rev. 1987, 87, 433−481. (6) Kole, G. K.; Vittal, J. J. Chem. Soc. Rev. 2013, 42, 1755−1775. (7) Yang, S. − Y.; Naumov, P.; Fukuzumi, S. J. Am. Chem. Soc. 2009, 131, 7247−7249. (8) Medishetty, R.; Vittal, J. J. Struct. Bonding (Berlin, Ger.) 2014, 157, 105−144. (9) Bučar, D.-K.; Papaefstathiou, G. S.; Hamilton, T. D.; Chu, Q. L.; Georgiev, I. G.; MacGillivray, L. R. Eur. J. Inorg. Chem. 2007, 2007, 4559−4568. (10) Bhogala, B. R.; Captain, B.; Parthasarathy, A.; Ramamurthy, V. J. Am. Chem. Soc. 2010, 132, 13434−13442. (11) Phan, N. H.; Halasz, I.; Opahle, I.; Alig, E.; Fink, L.; Bats, J. W.; Cong, P. T.; Lerner, H. − W.; Sarkar, B.; Wolf, B.; Jeschke, H. O.; Lang, M.; Valentí, R.; Dinnebier, R.; Wagner, M. CrystEngComm 2011, 13, 391−395. (12) MacGillivray, L. R.; Papaefstathiou, G. S.; Frišcǐ c′, T.; Hamilton, T. D.; Bučar, D. K.; Chu, Q.; Varshney, D. B.; Georgiev, I. G. Acc. Chem. Res. 2008, 41, 280−291. (13) Santra, R.; Biradha, K. CrystEngComm 2008, 10, 1524−1526. (14) Santra, R.; Biradha, K. CrystEngComm 2011, 13, 3246−3257. (15) Dutta, S.; Bučar, D.-K.; MacGillivray, L. R. Org. Lett. 2011, 13, 2260−2262. (16) Liu, D.; Lang, J.-P. CrystEngComm 2014, 16, 76−81. (17) Yang, S. − Y.; Deng, X. − L.; Jin, R. − F.; Naumov, P.; Panda, M. K.; Huang, R. − B.; Zheng, L. − S.; Teo, B. K. J. Am. Chem. Soc. 2014, 136, 558−561. (18) Han, Y. − F.; Lin, Y.-J.; Jia, W.-G.; Wang, G.-L.; Jin, G.-X. Chem. Commun. 2008, 1807−1809. (19) Sun, J.-K.; Tan, B.; Cai, L.-X.; Chen, R.-P.; Zhang, J.; Zhang, J. Chem. - Eur. J. 2014, 20, 2488−2495.
Figure 7. ORTEP drawing of 2-HT.
ring in 2-HT exhibits planarity, which is similar to the CB rings observed in 2a′−2c′. Notably the C−C bond distances (1.546 and 1.586 Å) of CB in 2-HT were also found to be in the same range as those observed in 2a′−2c′ (1.590, 1.543, 1.612 and 1.559, 1.496, and 1.609 Å). The N···X distance 3.587 Å was also found to be almost similar to that observed in 2a′−2c′ (3.418− 3.465 Å). It was demonstrated that UBOs 1 and 2 are photoreactive and yield HH-dimers upon irradiation. The HT-dimers of 1 and 2 were successfully obtained by synthesizing and irradiating their Ag(I) complexes. In the case of Ag(I) complexes of 1, the reactions are templated by Ag···Ag interactions, while in the case of Ag(I) complexes of 2 they are templated by Ag···π interactions. Further, the templation by Ag···π interactions in Ag(I) complexes of 2 resulted in facile SCSC transformations in all three cases studied. This clearly demonstrates that the Ag···π interactions are also equally important in templating the reactions similar to Ag···Ag interactions. By changing the pyridine substitution, Ag···Ag interactions can be converted to Ag···π interactions due to the positional mismatch. It may be noted that bis-pyridylethylene containing two different pyridine substitutions were shown to form HH-dimers using organic templates in a programmed manner.37−40 D
DOI: 10.1021/acs.cgd.5b01624 Cryst. Growth Des. XXXX, XXX, XXX−XXX
Crystal Growth & Design
Communication
(20) Han, Y.-F.; Jin, G.-X.; Hahn, F. E. J. Am. Chem. Soc. 2013, 135, 9263−9266. (21) Liu, D.; Lang, J. − P.; Abrahams, B. F. Chem. Commun. 2013, 49, 2682−2684. (22) Wang, Z.; Randazzo, K.; Hou, X.; Simpson, J.; Struppe, J.; Ugrinov, A.; Kastern, B.; Wysocki, E.; Chu, Q. R. Macromolecules 2015, 48, 2894−2900. (23) Santra, R.; Biradha, K. Cryst. Growth Des. 2010, 10, 3315−3320. (24) Han, Y.-F.; Jin, G.-X.; Daniliuc, C. G.; Hahn, F. E. Angew. Chem., Int. Ed. 2015, 54, 4958−4962. (25) Hutchins, K. M.; Rupasinghe, T. P.; Ditzler, L. R.; Swenson, D. C.; Sander, J. R. G.; Baltrusaitis, J.; Tivanski, A. V.; MacGillivray, L. R. J. Am. Chem. Soc. 2014, 136, 6778−6781. (26) Santra, R.; Banerjee, K.; Biradha, K. Chem. Commun. 2011, 47, 10740−10742. (27) Santra, R.; Garai, M.; Mondal, D.; Biradha, K. Chem. - Eur. J. 2013, 19, 489−493. (28) Kole, G. K.; Tan, G. K.; Vittal, J. J. Cryst. Growth Des. 2012, 12, 326−332. (29) Elacqua, E.; Groeneman, R. H.; Reinheimer, E. W.; Bučar, D.-K.; MacGillivray, L. R. Supramol. Chem. 2014, 26, 207−213. (30) Nagarathinam, M.; Vittal, J. J. Angew. Chem., Int. Ed. 2006, 45, 4337−4341. (31) Chu, Q.; Swenson, D. C.; MacGillivray, L. R. Angew. Chem., Int. Ed. 2005, 44, 3569−3572. (32) Kole, G. K.; Medishetty, R.; Koh, L. L.; Vittal, J. J. Chem. Commun. 2013, 49, 6298−6300. (33) Georgiev, I. G.; Bučar, D.-K.; MacGillivray, L. R. Chem. Commun. 2010, 46, 4956−4958. (34) Sinnwell, M. A.; Baltrusaitis, J.; MacGillivray, L. R. Cryst. Growth Des. 2015, 15, 538−541. (35) Samai, S.; Ghosh, P.; Biradha, K. Chem. Commun. 2013, 49, 4181−4183. (36) The 4-pyridyl derivative is found to be photostable as indicated by its crystal structure. Further, its AgClO4-complex forms head-to-tail dimer that shows low reactivity (13%) even after irradiation for several days. (37) Varshney, D. B.; Papaefstathiou, G. S.; MacGillivray, L. R. Chem. Commun. 2002, 1964−1965. (38) Hamilton, T. D.; Bučar, D.-K.; MacGillivray, L. R. Chem. Commun. 2007, 49, 1603−1604. (39) Nath, N. K.; Manoj, K.; Gâz, A. Ş.; Naumov, P. Chem. - Eur. J. 2013, 19, 8094−8099. (40) Hamilton, T. D.; Papaefstathiou, G. S.; MacGillivray, L. R. J. Am. Chem. Soc. 2002, 124, 11606−11607.
E
DOI: 10.1021/acs.cgd.5b01624 Cryst. Growth Des. XXXX, XXX, XXX−XXX
