Intramolecular Nitro-Aromatic Interactions Within a Molecular Torsion

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Intramolecular Nitro-Aromatic Interactions Within a Molecular Torsion Balance: A Quantitative Assessment Brijesh Bhayana, and Diane A. Dickie Cryst. Growth Des., Just Accepted Manuscript • DOI: 10.1021/acs.cgd.8b01138 • Publication Date (Web): 18 Oct 2018 Downloaded from http://pubs.acs.org on October 19, 2018

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Crystal Growth & Design

Intramolecular Nitro-Aromatic Interactions Within a Molecular Torsion Balance: A Quantitative Assessment Brijesh Bhayana,*a Diane A. Dickie

a

b

Wellman Center for Photomedicine, Massachusetts General Hospital, 70

Blossom Street, Boston, MA, 02114.

b

Department of Chemistry, Brandeis University, 415 South Street, Waltham,

MA, 02454; current address: Department of Chemistry, P.O. Box 400319, University of Virginia, Charlottesville, VA, 22904

KEYWORDS nitro, aromatic, electrostatic, interactions, nitro-π, substituent.

ABSTRACT: Interactions between a nitro group and an aromatic ring have been identified as an important aspect within the solid-state structures of many

ACS Paragon Plus Environment

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Crystal Growth & Design 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

energetic

materials.

We

investigated

Page 2 of 37

nitro-aromatic

interactions

within

a

molecular ‘torsion balance’, both in solid-state as well as in solution. Our balance features a Tröger’s base and a nitroalkene functionality substituted at 1 and 8 positions of a naphthalene ring.

Due to restricted rotation around a

biaryl axis, the balance can adapt two principal atropisomeric conformations -

folded and unfolded.

Intramolecular nitro-aromatic interactions are feasible only

in the folded state. A torsion balance containing a highly electron deficient aromatic ring crystallized in the folded state leading to the formation of a short (< 3.4 Å) intramolecular NO···aromatic contact.

On the other hand, with an

electron rich aromatic, the balance crystallized in the unfolded conformation in which the nitro group avoids the aromatic surface.

In solution, the strength of

the interactions was determined to be < 1 kcal/mol in different solvents. A substituent effect study showed that the interactions included a component of the electrostatic forces.


2

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The nitro group has been assessed to be participating in noncovalent interactions with the neighboring groups within the X-ray crystal structures of many compounds. The implications of such interactions on properties such as stability, packing, morphology, and photophysical characteristics of crystals have been deemed important.1

- 21

One of the first example of such interactions was

disclosed by Parrish and coworkers in context of the solid-state structure of picryl bromide (2,4,6-trinitrobromobenzene), an important energetic material.22

- 25

Polymorphs of this highly electron-deficient aromatic molecule contained intersheet sub-van der Waals nitro-aromatic edge-to-face contacts which were surmised to be of reasonable interaction energies. A CSD survey by the authors of that study yielded hundreds of structures containing a nitro oxygen within 3.2 Å of an aromatic ring centroid, leading them to conclude that “there

is a general penchant for molecules involving nitro groups to use such an interaction to assemble and stabilize themselves in the solid-state”.22,

23

In a

subsequent computational study, Karle et al. estimated picryl bromide’s edge-toface nitro-aromatic interactions energy to between 2 -12 kcal/mol.26 The nitro-


3


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aromatic interactions have not yet been quantified experimentally. Therefore, we studied these interactions using the torsion balance strategy conceived by Wilcox’s group nearly two decades ago.27

- 40

Such studies have provided

valuable insights into the nature of various weak noncovalent interactions and have been of high interest to computational chemists.41

- 48

CH3NO2 NH4OAc 90 oC, 2h O

B

H NO2 N

O

N Br CHO Pd(OAc)2/SPhos K2CO3 EtOH 80 oC, 4h

N N X

CHO

70 - 80%

X

N N 25 - 40%

X CH3PPh3Br KtOBu THF, 50 oC, 12h

H H N N 75 - 90% X

SCHEME 1. Synthetic route used to prepare the new balances.


4

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X1 X2 X3

X4 Nitroalkene Control Balance

Balance

(Y1 = NO2 (Y1

=

and

H and

Y2 = H)

Y2

=

H)

H

H

H

H

1a

2a

H

H

CH3

H

1b

2b

H

H

OCH3

H

1c

2c

H

H

NO2

H

1d

2d

H

H

F

H

1e

2e

F

F

H

H

1f

2f

F

F

F

H

1g

2g

F

F

F

F

1h

2h


5


Page 6 of 37

Table 1. Various analogues of the torsion balance prepared in this study.

Synthesis.

Our torsion balance consists of a Tröger’s-base, which is a rigid

T-shaped molecule, and a nitroalkene moiety substituted at positions 1 and 8 of a naphthalene ring.27

- 29

Scheme 1 shows the general synthetic strategy for

the preparation of various analogues of the balance. The pinacolborane esters of the Tröger’s bases were synthesized using established procedures and coupled to 1-bromo-8-naphthaldehyde using the Suzuki-Miyaura cross-coupling reaction to furnish the intermediate naphthaldehydes in acceptable yields.49

- 53

The aldehydes were converted to nitroalkenes (compounds 1a - 1h, table 1) using the Henry reaction and also to vinyl alkenes (compounds 2a - 2h, table 1), in order to furnish balances lacking a nitro group, using the Wittig reaction. We surmised that a comparative study of the vinyl alkene and the nitroalkene balance could provide insights into how the nitro group specifically affects the folding phenomenon.

Even though there is only one ortho substituent along

the biaryl axis, the energy barrier to rotation within the torsion balance is


6

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relatively high, with the ∆G‡ value estimated to be ≈ 17 kcal/mol from the coalescence of the Ar-CH3 peaks at T = 60o C (in DMSO-d6) of balance 2b. The two atropisomers have a few distinct NMR signals even at the room temperature.

Figure 1. Solid-state structures of balances 1g (left) and 1b (right).


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Figure 2. Stacking between 1g’s.


8

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C28

H28B

H28A 3.208(2)

C5

Figure 3. Solid-state structure of balance 2b.


9


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Solid-state analysis. We were successful in obtaining the crystallographic structures of balances 1b, 1g and 2b (Figures 1, 2 and 3).

Slow evaporation

of the solvent from their solutions prepared in methanol/dichloromethane mixture (see SI for details) provided crystals suitable for X-ray analysis. Balance 1b crystallized in the unfolded state whereas balances 1g and 2b crystallized in the folded state. For these balances, the solid-state and the preferred solution state (in CD3OD) conformations were the same. Within 1g the closest NO···aromatic contact distance is between O1···C5, at 3.2637(19) Å, while the O1···centroid and O2···centroid distances are 3.5707(14) and 3.6879(12) Å, respectively. Although we did not observe a sub-van der Waals nitro···aromatic contact, the O1···C5 distance is close in value to the sum (3.2 Å) of the van der Waals radii of carbon and oxygen.54

- 55

The nitro group is situated above

the edge of the bottom aromatic and not as near the centroid as in picryl


10

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bromide.22 As can be seen in Figure 1, balance 1b is more opened up than balance 1g. The diazocine hinge angles, as measured by the angles between the planes of the aromatic rings on either side of the hinge, are 111.47(5)o for 1b and 82.54(6)o for 1g. These values are just above the upper and lower limits of the range for similar compounds.51 Because of the steric constraints of the molecules, there is a small distortion in the planarity of the napthyl rings. The angle between the planes of the two rings comprising the naphthyl fragment is 4.59(5) and 7.92(6)o for 1b and 1g, respectively. Somewhat surprisingly, given the electronic differences between the two compounds there are no significant differences in the nitro bond lengths. Face-to-face stacking of the fluorinated rings between two neighbouring torsion balances was observed within the packing of 1g. A notable feature of this arrangement is that the electron rich carbons (bonded to C, H or N) of one aromatic face the electron deficient carbons (bonded to F) of the other aromatic. Evidently, stacking involves a role of electrostatic forces. The shortest contact is between C4···C6’, measuring 3.314(2) Å, and the centroid···centroid distance is 3.5428(8) Å. No


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significant intermolecular contacts were noted in 1b.

Within 2b, the shortest

CH···aromatic contact is between H28A···C5, calculated to be 3.208(2) Å. The H28B···C5 calculated distance is 4.366 (2) Å and the C5···C28 distance is 4.088 (2) Å.

unfolded

ΔGo ,

folded

CDCl3

(CD3)2CO

CD3OD

C6D6

1a

0.41

-a

0.61

0.47

2a

-0.05

-0.06

-0.18

-0.11

1b

0.52

0.82

0.60

0.54

2b

0.03

0.02

-0.13

0.0

1c

0.38

0.71

0.41

0.41

2c

0.03

-0.02

-0.14

-0.11

1d

0.12

0.09

0.0

0.35

Solvent

Balance


12

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2d

0.03

-0.08

-0.11

0.17

1e

0.28

0.48

0.32

0.37

2e

-0.04

-0.08

-0.13

-0.02

1f

0.11

0.34

0.17

0.11

2f

-0.03

-0.05

-0.06

0.0

1g

-0.06

-0.06

-0.2

0.0

2g

0.06

-0.06

-0.11

0.17

1h

-0.1

-0.54

-0.65

-0.1

2h

0.17

0.02

0.03

0.54

Table 1. The equilibrium ΔGo values, in kcal/mol, for the balances. The NMR data were recorded at 298 K.

a

Distinct NMR peaks were not observed. The

error in ΔGo values is estimated at ± 0.03 kcal/mol, based on δK of ± 5%.

folded

unfolded

1e 1f

1g

1h


13


Figure 4. Ar-HC=13CHNO2 peaks of

13C

Page 14 of 37

enriched fluorinated balances 1e, 1f, 1g

and 1h.

Study of the conformational equilibrium in solution (in CDCl3 at 298 K). The [folded] and [unfolded] values were determined from the area integrals of (for balances 2a – 2h) and

13C

(for

13C

1H

enriched 1a – 1h) NMR peaks, and the

equilibrium constant defined as K = [folded]/[unfolded].

The ΔGo values were

obtained from the Eyring equation: ΔGo = -RT*ln*(K). Balances 1a – 1f showed a preference for the unfolded state, (ΔGo > 0), whereas 1g and 1h preferred the folded state, (ΔGo < 0).

Overall, the ΔGo values were small and within 1

kcal/mol. As a general trend, folding increased with a decrease in electron density over the bottom ring due to the electron-withdrawing inductive effect of the aromatic substituents. For example (see figure 4) while the monofluoro and difluoro balances (1e and 1f respectively) showed a preference for the unfolded state, within the trifluoro balance (1g) this preference was lost. A clear preference for folded state emerged within the tetrafluoro balance (1h). The


14

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ΔGo values for balances 2a – 2h were mostly close to zero, even though the solid-state structure of 2b shows a short CH-aromatic contact distance. In our previous study, a torsion balance very similar to 2b (the methoxy torsion balance in ref. 29) also did not show a preference for the folded state or any evidence of favourable CH-aromatic interactions in solution. The Hammett σmeta values correlate to an aromatic substituent’s electrostatic effects and the ΔGo vs. ∑σmeta plots provide insights into the nature of the interactions.56

- 62

A good

(R2 = 0.97) inverse linear correlation between ΔGo and ∑σmeta is observed for the nitroalkenes (chart 1), whereas, for the vinyl alkenes the correlation is nearly absent (R2 = 0.5). Thus, the presence of the nitro group makes the conformational equilibrium of the torsion balance sensitive to the molecular electrostatic potential over the aromatic, suggesting that the nitro and the aromatic interact electrostatically.

In addition to the electrostatic forces, other

through-space interactions such as attractive dispersion interactions can also be expected

to

exist

between

the

nitro

and

the

aromatic.

Through-space

interactions do not require an orbital overlap or sub-van der Waals contact


15


Page 16 of 37

distance (d < ∑ rvdW), however, they can decay rapidly with the interactions distance as in the case of dispersion forces which follow an interaction energy

 1/r6 law. Houk and Wheeler have highlighted the importance of through-space substituent-aromatic interactions in context of π···π stacking.58,

59

Contributions

from individual forces to the overall ΔGo value is challenging to ascertain.

Our

ΔGo vs. ∑σmeta plots suggest that the repulsive electrostatic component is attenuated by EWG’s.

The ΔΔGo (= ΔGonitroalkene – ΔGovinyl) value can be

assumed to represent the free energy associated with the nitro-aromatic binding.

This quantity is within a ± 1 kcal/mol range, indicating the nitro-

aromatic interactions to be similar in strength to other weak noncovalent interactions such as the aromatic···aromatic, CH···π, amide···amide and CF···C=O interactions which have been studied using the Wilcox torsion balance. 63 - 66

It is interesting to note that within the fluorinated series of balances, each

additional fluorine atom stabilizes the nitro-aromatic binding by a ΔΔGo value of about 0.2 kcal/mol.


16

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0.20

0.15

ΔGo (kcal/mol)

0.10

0.05

0.00 -0.60

-0.40

-0.20

0.00

0.20

-0.05

0.40

0.60

0.80

1.00

1.20

∑σmeta

-0.10

0.6 0.5 0.4

ΔGo (kcal/mol)

0.3 0.2 0.1 0

-0.6

-0.4

-0.2

0

0.2

-0.1 -0.2

0.4

0.6

0.8

1

1.2

∑σmeta

Chart 1. Δ GoCDCl3 vs. ∑ σ meta plots for the vinyl alkene balance (top) and the nitroalkene balance (bottom).


17


Page 18 of 37

Effect of solvent on conformational equilibrium: The NMR data were recorded in four kinds of solvents (table 1): halogenated (CDCl3), polar-organic ((CD3)2CO), protic (CD3OD) and aromatic (C6D6). profoundly different solvation environments.

These solvents provide

They can interact with the aromatic

rings of the torsion balance via halo···π, CH···π, OH···π and π···π interactions, respectively, and compete with the intramolecular nitro···π interactions. The effects of microsolvation on conformational equilibria of torsion balances has been explored in many papers.27

- 40

We observed that the ΔGo values spanned

a wider range for the nitroalkenes in comparison to the vinyl alkenes.

The

ΔGo vs. ∑σmeta linear correlation was also much superior for the nitroalkenes. For the nitroalkenes, the slope of the linear fits in the ΔGo vs. ∑σmeta plots (see SI) followed the following order in solvent: acetone > methanol > chloroform > benzene, implying the ΔGo to be most sensitive to the substituent in acetone. Thus, the intramolecular nitro-aromatic interactions influenced the conformational equilibrium in a variety of solvation environments.


The range for

18

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the ΔGo values, however, did not change markedly and was within 1 kcal/mol for all solvents. Wilcox also observed the ΔGo values of CH··· and ··· interactions to be confined within 1 kcal/mol in various solvents.27,

28

Balance 2h showed a remarkably high preference for the unfolded state in C6D6 which could be due to favorable electrostatic ··· interactions between the solvent and the perfluorinated aromatic. Such interactions explain the interesting phenomenon observed during the mixing of hexafluorobenzene and benzene.67

In conclusion, we have introduced a new torsion balance within which the two principal atropisomeric conformational states differ by the position of a nitro group with respect to an aromatic ring.

The conformational equilibrium of the

balance can be studied at the room temperature via NMR spectroscopy. Crystallographic and solution-state studies indicate the formation of weak interactions between the nitro group and the aromatic ring within the balance in


19


Page 20 of 37

the folded conformation. Substituent-effect studies suggest that the nitroaromatic interactions contain a component of electrostatic forces. The nitro oxygen atoms carry a negative potential and engage in repulsive electrostatic interactions with the electron cloud over the aromatic. This repulsion is attenuated upon introduction of electron-withdrawing aromatic substituents and the nitro-aromatic interactions even become overall attractive for a perfluorinated aromatic. The ΔGo values indicate the nitro-aromatic interactions to be similar in strength to various other noncovalent interactions.

Hopefully, our results will

stimulate further research into these interesting interactions.

They could be of

particular interest to those involved in synthesis and crystal engineering of novel energetic materials. ACKNOWLEDGEMENTS

The authors thank Professors Craig Wilcox (Pittsburgh), Ken Shimizu (South Carolina), Scott Cockroft (Edinburgh) and Bruce Foxman (Brandeis) for their advice and support.


20

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ASSOCIATED CONTENT

Supporting Information. Synthesis procedures, crystallographic characterizations, PXRD patters for compounds 1b and 2b, Hammett plots, 1H and

13C

NMR

spectra.

AUTHOR INFORMATION Corresponding Author * Brijesh Bhayana, Wellman Center for Photomedicine, Massachusetts General Hospital, 70 Blossom Street, Boston, MA, 02114. Email: [email protected]

REFERENCES 1. Allen, F. H.; Baalham, C. A.; Lommerse, J. P. M.; Raithby, P. R.; Sparr, E. Hydrogen-Bond Acceptor Properties of Nitro-O Atoms: A Combined Crystallographic Database and Ab Initio Molecular Orbital Study. Acta Cryst. 1997, B53, 1017-1024.


21


Page 22 of 37

2. Mitchell, L. A.; Imler, G. H.; Parrish, D. A.; Deschamps, J. R.; Leonard, P. W.; Chavez, D. E. Crystal structures of the three closely related compounds: bis[(1H-tetrazol-5-yl)methyl]-nitramide, triaminoguanidinium 5-({[(1H-tetrazol- 5yl)methyl](nitro)amino}methyl)tetrazol-1-ide, and diammonium bis[(tetrazol-1-id-5yl)methyl]-nitramide monohydrate, Acta Cryst. 2017, E73, 1056–1061.

3. Kumar, D.; Imler, G. H.; Parrish, D. A.; Shreeve, J. M. A Highly Stable and Insensitive Fused Triazolo–Triazine Explosive (TTX). Chem.—Eur. J. 2017, 23 (8), 1743–1747.

4. Chiarucci, M.; Ciogli, A.; Mancinelli, M.; Ranieri, S.; Mazzanti, A. The Experimental Observation of the Intramolecular NO2/CO Interaction in Solution.

Angew. Chem., Int. Ed. 2014, 53, 5405– 5409.

5. He, C.; Yin, P.; Mitchell, L. A.; Damon A. Parrish, D. A.; Shreeve, J. M. Energetic aminated-azole assemblies from intramolecular and intermolecular N– H⋯O and N–H⋯N hydrogen bonds. Chem. Commun. 2016, 52, 8123.


22

Page 23 of 37 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


6. Yin, P.; Shreeve, J. M. Heterocyclic Chemistry in the 21st Century: A Tribute

to Alan Katritzky, Advances in Heterocyclic Chemistry. 2017, 121(4), 89-131.

7. Zhang, J.; Dharavath, S.; Mitchell, L. A.; Parrish, D. A.; Shreeve, J. M. Energetic Salts Based on 3,5-Bis(dinitromethyl)-1,2,4-triazole Monoanion and Dianion: Controllable Preparation, Characterization, and High Performance. J.

Am. Chem. Soc. 2016, 138, 7500−7503.

8. Deschamps, J. R.; Straessler, N. A. Structure of O-Methyltrinitrophloroglucinol Derivatives. J. Chem. Crystallogr. 2011, 41:971–975.

9. Pindelska, E.; Dobrzycki, L.; Wozniak, K.; Kolodziejski, W. Polymorphism of Crystalline 4-Amino-2-Nitroacetanilide. Cryst. Growth Des. 2011, 11, 2074–2083.

10. Pengshung, M.; Bard, R. R.; Valente, E. J. The Bis(triethylammonium) Salt of 3,5,12- Trinitrotricyclo[5.3.1.12,6]dodecan-8,10,11-trione-3,8-(NO2,O)-dianion. J.

Chem. Cryst. 46 (10-12), 429-434.

11. Oburn, S. M.; Bosch, E. Unexpected beauty and diversity in the structures of three homologous 4,5-dialkoxy-1-ethynyl- 2-nitrobenzenes: the subtle interplay


23


Page 24 of 37

between intermolecular C—H…O hydrogen bonds and alkyl chain length. Acta

Cryst. 2017, C73, 814 –819.

12. Kulkarni, G. U.; Kumaradhas, P.; Rao, C. N. R. Charge Density Study of the Polymorphs of

p-Nitrophenol. Chem. Mater. 1998, 10, 3498-3505.

13. Coppens, P.; Schmidt, G. M. J. The Crystal Structure of the Metastable (ß) Modification of p-Nitrophenol, Acta Cryst. 1965, 18, 654.

14. Grygoryeva, K.; Kubecǩa, J.; Pysanenko, A.; Lengyel, J.; Slavícěk, P.; Faŕník, M. Photochemistry of Nitrophenol Molecules and Clusters: Intra- vs Intermolecular Hydrogen Bond Dynamics. J. Phys. Chem. A. 2016, 120, 4139−4146.

15. Shugrue, C. R.; DeFrancisco, J. R.; Metrano, A. J.; Brink, B. D.; Nomoto, R. S.; Linton, B. R. Detection of weak hydrogen bonding to fluoro and nitro groups in solution using H/D exchange, Org. Biomol. Chem. 2016, 14, 2223– 2227.


24

Page 25 of 37 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


16. Laurence, C.; Berthelot, M.; Lucon, M.; Morris, D. G. Hydrogen-bond basicity of nitro-compounds. J. Chem. Soc., Perkin Trans. 2 1994, 491.

17. Etter, M. C.; Urbanczyk-Lipkowska, Z.; Zia-Ebrahimi, M.; Panunto, T. W. Hydrogen bond-directed cocrystallization and molecular recognition properties of diarylureas. J. Am. Chem. Soc. 1990, 112, 8415– 8426.

18. Bu, J.; Lilienthal, N. D.; Woods, J. E.; Nohrden, C. E.; Hoang, K. T.; Truong, D.; Smith, D. K. Electrochemically Controlled Hydrogen Bonding. Nitrobenzenes as Simple Redox-Dependent Receptors for Arylureas. J. Am.

Chem. Soc. 2005, 127, 6423– 6429

19. Ungnade, H. E.; Roberts, E. M.; Kissinger, L. W. Hydrogen Bonding in Nitro Compounds. J. Phys. Chem. 1964, 68, 3225– 3228.

20. Kelly, T. R.; Kim, M. N. Relative Binding Affinity of Carboxylate and Its Isosteres: Nitro, Phosphate, Phosphonate, Sulfonate, and -Lactone. J. Am.

Chem. Soc. 1994, 116, 7072-7080.


25


Page 26 of 37

21. Rablen, P. R.; Lockman, J. W.; Jorgensen, W. L. Ab Initio Study of Hydrogen-Bonded Complexes of Small Organic Molecules with Water. J. Phys.

Chem. A 1998, 102, 3782-3797.

22. Parrish, D. A.; Deschamps, J. R.; Gilardi, R. D.; Butcher, R. J. Polymorphs of Picryl Bromide. Cryst. Growth Des. 2007, 8, 57 - 62.

23. Deschamps, J. R.; Parrish, D. A. Stabilization of Nitro-Aromatics.

Propellants Explos. Pyrotech. 2015, 40, 506 – 513.

24. Kaafarani, B. R.; Wex, B.; Oliver, A. G.; Krause-Bauer, J. A.; Neckers, D. C. π, π-Stacking and Nitro-π-Stacking Interactions of 1- (4-Nitrophenyl)-4-phenyl2,4-bis(phenylethynyl)butadiene. Acta Cryst., Sect. E, 2003, 59, o227–o229.

25. Sanchez-Moreno, M. J.; Choquesillo-Lazarte, D.; Gonzalez- Perez, J. M.; Carballo, R.; Martı́n-Ramos, J. D.; Castiñeiras, A.; Niclos-Gutierrez, J. Ring-Ring or Nitro-Ring π, π-Interactions in N-(p-Ni- trobenzyl)-iminodiacetic Acid (H2NBIDA) and Mixed-Ligand Copper(II) Complexes of NBIDA and Imidazole (Him), 2,2’-Bi-pyridine (bipy) or 1,10-Phenanthroline (phen). Crystal Structures of


26

Page 27 of 37 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


H2NBIDA, [Cu(NBIDA)(Him)(H2O)] , [Cu(NBIDA)(bipy)]·3H2O and [Cu(NBIDA)(phen)]·2H2O. Polyhedron, 2003, 22:8, 1039 – 1049.

26. Huang, L.; Massa, L.; Karle, J. Calculated Interactions of a Nitro Group with Aromatic Rings of Crystalline Picryl Bromide. Proc. Natl. Acad. Sci. USA, 2008, 105 (37), 13720 - 13723.

27. Kim, E.; Paliwal, S.; Wilcox, C. S. Measurements of Molecular Electrostatic Field Effects in Edge-to-Face Aromatic Interactions and CH-π Interactions with Implications for Protein Folding and Molecular Recognition. J.

Am. Chem. Soc. 1998, 120 (43), 11192-11193.

28. Paliwal, S.; Geib, S.; Wilcox, C. S. Molecular Torsion Balance for Weak Molecular Recognition Forces. Effects of "Tilted-T" Edge-to-Face Aromatic Interactions on Conformational Selection and Solid-State Structure. J. Am.

Chem. Soc., 1994, 116 (10), 4497 – 4498.


27


Page 28 of 37

29. Bhayana, B. Wilcox Molecular Torsion Balance with Rigid Side Arm and Separable Atropisomers for Investigating CH − π Interactions. J. Org. Chem., 2013, 78 (13), 6758 – 6762.

30. Yang, L.; Adam, C.; Cockroft, S. L. Quantifying Solvophobic Effects in Nonpolar Cohesive Interactions, J. Am. Chem. Soc. 2015, 137 (32), 10084 – 10087.

31. Ams, M. R.; Fields, M.; Grabnic, T.; Janesko, B. G.; Zeller, M.; Sheridan, R.; Shay, A. Unraveling the Role of Alkyl F on CH−π Interactions and Uncovering the Tipping Point for Fluorophobicity. J. Org. Chem., 2015, 80 (15), 7764 – 7769.

32. Lypson, A. B.; Wilcox, C. S. Synthesis and NMR Analysis of a Conformationally Controlled β-Turn Mimetic Torsion Balance. J. Org. Chem., 2017, 82 (2), 898 – 909.


28

Page 29 of 37 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


33. Bhayana, B.; Wilcox, C. S. A Minimal Protein Folding Model to Measure Hydrophobic and CH–π Effects on Interactions between Nonpolar Surfaces in Water. Angew. Chem., Int. Ed., 2007, 46, 6833 – 6836.

34. Yang, L.; Adam, C.; Nichol, G. S.; Cockroft, S. L. How much do van der Waals dispersion forces contribute to molecular recognition in solution? Nat.

Chem. 2013, 5, 1006 – 1010.

35. Adam, C.; Yang, L.; Cockroft, S. L. Partitioning Solvophobic and Dispersion Forces in Alkyl and Perfluoroalkyl Cohesion. Angew. Chem., Int. Ed. 2015, 54, 1164– 1167.

36. Mati, I. K.; Adam, C.; Cockroft, S. L. Seeing through solvent effects using molecular balances. Chem. Sci., 2013, 4, 3965 - 3972.

37. Cockroft, S. L.; Hunter, C. A. Desolvation tips the balance: solvent effects on aromatic interactions. Chem. Commun. 2006, 36, 3806.

38. Cockroft, S. L.; Hunter, C. A. Desolvation and substituent effects in edgeto-face aromatic interactions. Chem. Commun. 2009, 3961.


29


Page 30 of 37

39. Maier, J. M.; Li, P.; Vik, E. C.; Yehl, C. J.; Strickland, S. M. S.; Shimizu, K. D. Measurement of Solvent OH−π Interactions Using a Molecular Balance. J.

Am. Chem. Soc. 2017, 139, 6550– 6553.

40. Emenike, B. U.; Spinelle, R. A.; Rosario, A.; Shinn, D. W.; Yoo, B. Solvent Modulation of Aromatic Substituent Effects in Molecular Balances Controlled by CH−π Interactions. J. Phys. Chem. A 2018, 122 (4), 909-915.

41. Řezáč, J.; Hobza, P. Benchmark Calculations of Interaction Energies in Noncovalent Complexes and Their Applications. Chem. Rev. 2016, 116, 5038– 5071.

42. Hohenstein, E. G.; Sherrill, C. D. Wavefunction methods for noncovalent

interactions WIREs Comput. Mol. Sci. 2012, 2, 304– 326.

43. Takahashi, O.; Kohno, Y.; Nishio, M. Relevance of Weak Hydrogen Bonds in the Conformation of Organic Compounds and Bioconjugates: Evidence from Recent Experimental Data and High-Level ab Initio MO Calculations. Chem.

Rev. 2010, 110, 6049– 6076.


30

Page 31 of 37 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


44. Sinnokrot, M. O.; Sherrill, C. D. High-Accuracy Quantum Mechanical Studies of π−π Interactions in Benzene Dimers. J. Phys. Chem. A, 2006, 110 (37), 10656 – 10668.

45. Sherrill, C. D. Energy Component Analysis of π Interactions. Acc. Chem.

Res., 2013, 46 (4), 1020 – 1028.

46. Ribas, J.; Cubero, E.; Luque, F. J.; Orozco, M. Theoretical Study of Alkylπ and Aryl-π Interactions. Reconciling Theory and Experiment. J. Org. Chem., 2002, 67 (20), 7057 – 7065.

47. Sherman, M. C.; Ams, M. R.; Jordan, K. D. Symmetry-Adapted Perturbation Theory Energy Analysis of Alkyl Fluorine–Aromatic Interactions in Torsion Balance Systems. J. Phys. Chem. A, 2016, 120 (46), 9292–9298.

48. Nakamura, K.; Houk, K. N. Theoretical Studies of the Wilcox Molecular Torsion Balance. Is the Edge-to-Face Aromatic Interaction Important? Org. Lett. 1999, 1, 2049– 2051.


31


Page 32 of 37

49. Faroughi, M.; Zhu, K.; Jensen, P.; Craig, D. C.; Try, A. C. One-Step Synthesis of Tröger's Base Hybrids Containing at Least One Halogen Atom.

Eur. J. Org. Chem. 2009, 4266-4272.

50. Vande Velde, C. M. L.; Didier, D.; Blockhuys. F.; Sergeyev, S. Racemic 1,2,3,4,7,8,9,10-octafluoro-6H,12H-5,11-methanodibenzo[b,f][1,5]-diazocine: an octafluorinated analogue of Tröger’s base. Acta Cryst., 2008, E64, o538.

51. Faroughi, M.; Try, A. C.; Klepetko, J.; Turner, P. Changing the shape of Tröger’s base. Tet. Lett. (2007), 48, 6548–6551.

52. Ishiyama, T.; Murata, M.; Miyaura, N. Palladium(0)-Catalyzed CrossCoupling Reaction of Alkoxydiboron with Haloarenes: A Direct Procedure for Arylboronic Esters. J. Org. Chem., 1995, 60, 7508-7510.

53. Olah, G. A.; Ohannesian, L.; Arvanaghi, M. N-Formylmorpholine: a New and Effective Formylating Agent for the Preparation of Aldehydes and Dialkyl (1-formylalkyl)phosphonates from Grignard or Organolithium Reagents. J. Org.

Chem., 1984, 49: 3856–3857.


32

Page 33 of 37 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


54. Bondi, A. Van der Waals Volumes and Radii. Phys. Chem. 1964, 68, 441– 451.

55. Schiemenz, G. P. The Sum of van der Waals Radii – A Pitfall in the Search for Bonding. Zeitschrift für Naturforschung B, 62 (2), 235–243.

56. Hwang, J.; Li, P.; Carroll, W. R.; Smith, M. D.; Pellechia, P. J.; Shimizu, K. D, Additivity of Substituent Effects in Aromatic Stacking Interactions. J. Am.

Chem. Soc. 2014, 136, 14060−14067.

57. Ringer, A. L.; Sherrill, C. D. Substituent Effects in Sandwich Configurations of Multiply Substituted Benzene Dimers Are Not Solely Governed by Electrostatic Control. J. Am. Chem. Soc. 2009, 131, 4574− 4575.

58. Wheeler, S. E. Understanding Substituent Effects in Noncovalent Interactions Involving Aromatic Rings. Acc. Chem. Res. 2013, 46, 1029– 1038.

59. Wheeler, S. E.; Houk, K. Substituent Effects in the Benzene Dimer are Due to Direct Interactions of the Substituents with the Unsubstituted Benzene.

J. Am. Chem. Soc., 2008, 130 (33), 10854–10855.


33


Page 34 of 37

60. Li, P.; Maier, J. M.; Vik, E. C.; Yehl, C. J.; Dial, B. E.; Rickher, A. E.; Smith, M. D.; Pellechia, P. J.; Shimizu, K. D. Stabilizing Fluorine–π Interactions.

Angewandte Chemie-International edition, 2017, 56 (25), 7209-7212.

61. Cockroft, S. L.; Hunter, C. A.; Lawson, K. R.; Perkins, J.; Urch, C. L. Electrostatic Control of Aromatic Stacking Interactions. J. Am. Chem.

Soc., 2005, 127 (24), 8594–8595.

62. Hammett, Louis P, The Effect of Structure upon the Reactions of Organic Compounds. Benzene Derivatives, J. Am. Chem. Soc. 1937, 59 (1): 96. For the diazocine nitrogen and methylene we used the σmeta values of N(CH3)2 and CH3 groups.

63. Fischer, F. R.; Schweizer, W. B.; Diederich, F. Molecular torsion balances: Evidence for favorable orthogonal dipolar interactions between organic fluorine and amide groups. Angew. Chem., Int. Ed., 2007, 46, 8270-8273.


34

Page 35 of 37 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


64. Fischer, F. R.; Wood, P. A.; Allen, F. H.; Diederich, F. Orthogonal Dipolar Interactions Between Amide Carbonyl Groups, Proc. Natl. Acad. Sci. U.S.A., 2008, 105, 17290-17294.

65. Fischer, F. R.; Schweizer W. B.; Diederich, F. Substituent Effects on the Aromatic Edge-to-Face Interaction, Chem. Commun. 2008, 4031-4033.

66. Hof, F.; Scofield, D. M.; Schweizer, W. B.; Diederich, F. A weak attractive interaction between organic fluorine and an amide group, Angew. Chem., Int.

Ed. 2004, 43, 5056-5059.

67. Patrick C. R.; Prosser, G. S. A Molecular Complex of Benzene and Hexafluorobenzene. Nature, 187, 1021.


35


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Intramolecular Nitro-Aromatic Interactions Within a Molecular Torsion Balance: A Quantitative Assessment Brijesh Bhayana,*a Diane A. Dickie

a

b

Wellman Center for Photomedicine, Massachusetts General Hospital, 70

Blossom Street, Boston, MA, 02114.

b

Department of Chemistry, Brandeis University, 415 South Street, Waltham,

MA, 02454; current address: Department of Chemistry, P.O. Box 400319, University of Virginia, Charlottesville, VA, 22904

SYNOPSIS Nitro-aromatic interactions guide the conformational equilibrium of a torsion balance. The interactions are usually repulsive but become attractive for highly electron deficient aromatics.


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Intramolecular Nitro-Aromatic Interactions Within a Molecular Torsion

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