Structural analysis of the foldecture derived from racemic peptide foldamers

Accepted Manuscript Structural analysis of the foldecture derived from racemic peptide foldamers Jintaek Gong, Jae-Hoon Eom, Rokam Jeong, Russell W. Driver, Hee-Seung Lee PII:

S1293-2558(17)30491-0

DOI:

10.1016/j.solidstatesciences.2017.05.014

Reference:

SSSCIE 5506

To appear in:

Solid State Sciences

Received Date: 18 May 2017 Accepted Date: 29 May 2017

Please cite this article as: J. Gong, J.-H. Eom, R. Jeong, R.W. Driver, H.-S. Lee, Structural analysis of the foldecture derived from racemic peptide foldamers, Solid State Sciences (2017), doi: 10.1016/ j.solidstatesciences.2017.05.014. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Structural Analysis of the Foldecture Derived from Racemic Peptide Foldamers

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Jintaek Gong, Jae-Hoon Eom, Rokam Jeong, Russell W. Driver and Hee-Seung Lee*

Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea

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E-mail: [email protected]

Abstract;

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The molecular packing structure of an elongated parallelogram plate shaped foldecture composed of a 1:1 racemic mixture of 11-helical peptide foldamers was resolved by powder X-ray diffraction (PXRD) analysis. A comprehensive Rietveld refinement procedure compensated for powder texture and identified the principal face of the foldecture. Each foldamer makes head-to-tail intermolecular hydrogen bonds, creating extended chains of single enantiomers that form a network of hydrophobic close contacts with foldamers of both the opposite and the same chiralities. An isosurface for anisotropic microstrain was calculated and found to be smallest along the x-axis, which is parallel to the network of intermolecular hydrogen bonds. Comparison with the single crystal

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structure found molecular packing motifs to be almost identical—a result infrequently observed in enantiopure

components.

Keywords;

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foldectures. This is the first powder X-ray diffraction structural analysis of a foldecture composed of multiple

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Foldecture of Racemic Foldamer ; Peptide Self-assembly ; Powder X-ray Diffraction ; Anisotropic Microstrain ; Enantiomer Pair

1. Introduction

Peptide self-assembly is a powerful method to prepare novel functional materials through bottom-up process that mimic natural systems. Although many different peptide-based materials have been reported[1-5], precise molecular-level control of individual peptides during self-assembly remains challenging. Our group has extensively analysed a family of three-dimensional microscale organic materials derived from the selfassembly of peptide foldamers, which we have termed “foldectures”.[6-8] Foldectures show highly homogeneous and unique morphologies, unusual physical properties and anisotropic chemical functionality that creates utility across a diverse set of applications.[9, 10] Foldectures composed of enantiopure foldamers

ACCEPTED MANUSCRIPT are proven to have well-defined molecular packing modes in non-centrosymmetric space groups that are different substantially from slowly grown single crystals.[11-13]

On the other hand, the self-assembly of a mixture of racemic foldamers remains largely unexplored, while the studies on the racemic crystallization are known to be very useful techniques for unravelling protein

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structures.[14-17] Although slow co-crystallization, which occurs near equilibrium, is fundamentally different from the rapid, non-equilibrium self-assembly processes that resulting in foldectures, we attempted to adopt the racemic protein crystallography principles to our foldecture study for the development of new types of foldectures derived from racemic foldamers. In considering the advantages of racemic self-assembly, we were particularly intrigued by the possibility that enantiomeric pairs of foldamers could initially co-assemble to

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form architectural units; the self-assembly of these units (rather than individual foldamers) could then lead to fundamentally new molecular packing modes that possess a centre of symmetry.[18] Furthermore, it was

enantiopure self-assembly fails.[15, 19-22]

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expected that racemic self-assembly would be an alternative way to facilitate foldecture formation when

In this context, we have previously studied the self-assembly of 1:1 racemic 11-helical peptide foldamers (R and S), and found that they formed to parallelogram plate shaped foldectures (FRS, Figure 1).[23] However, we unexpectedly failed to elucidate the molecular packing mode of the foldecture by our typical analysis

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techniques. In particular, it was difficult to determine the correct space group for this foldecture derived from racemic foldamers. Unlike the foldectures obtained from enantiopure foldamers which can only have 65 possible space groups, the number of possible group was increased to 230 in this case. This is because all symmetry operations are allowed in solid-state structure of the foldecture derived from racemic foldamers, while inversion of chiral centre was not allowed in the structure of enantiopure case. As a result, the number

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of selectable groups within the same unit cell parameter has increased dramatically. The results prompted us to combine our typical PXRD analysis methodology with racemic protein crystallography, which makes space group of racemic macromolecules theoretically predictable.[14-17] Herein we report the first molecular

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packing structure of the foldecture derived from a 1:1 mixture of racemic foldamers. We identified a specific unit cell edge vector with the principal face and calculated a microstrain isosurface that correlates anisotropic compressibility with the intermolecular hydrogen bonding network.

2. Experimental

2.1. Materials and synthesis Heptameric peptide foldamers R and S, composed of 1:1 alternating trans-2-aminocyclopentane carboxylic acid (ACPC) and aminoisobutyric acid (Aib) amino acid residues are chosen as substrates for this study. Both R and S enantiomers were synthesized by literature protocols[24, 25] (Figure 1).

ACCEPTED MANUSCRIPT 2.2. Circular dichroism (CD) spectroscopy Circular Dichroism spectra were measured using a Jasco J-815 spectrometer in 1 mm quartz cells in MeOH (0.1 mM) at 20°C. Spectra were recorded from 260 to 190 nm at a scanning rate of 100 nm/min and were

2.3. Co-assembly procedure of racemic peptide foldamers

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averaged over 10 scans. (Figure S1)

A solution of R and S in THF (200µL, 2g/L) was injected into an aqueous solution of vigorously stirred Pluronic® 123 (P123, 1 mL) and then stirred for 3 min at room temperature. The solvent mixture was allowed to stand for 2 hours at room temperature. The solution was centrifuged and the supernatant was carefully

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decanted. The residual white precipitate was washed with distilled water (2mL × 2). In order to observe the effect of P123 concentration on foldecture morphology, the P123 concentration was varied from 0 g/L to

2.4. Scanning electron microscopy

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48g/L. (Figure S2)

FRS were transferred to a Si(100) wafer and dried under ambient atmosphere. Scanning electron microscope (SEM) images were acquired on Inspect F50, FEI at an accelerating voltage of 10 kV after Pt coating (sputter

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coater 108auto, Cressington Scientific Instruments).

2.5. Synchrotron Powder X-ray Diffraction

Samples for PXRD experiments were prepared by our standard self-assembly protocol (P123 concentration;

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32 g/L, see section 2.3), and fully dried in vacuo before data collection. The white powder was placed in a zero background silica holder and rotated during data collection at 1 cycle per second. Diffraction patterns were collected on the 9B High-Resolution Powder Diffraction (9B HRPD) Beamline of the Pohang

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Accelerator Laboratory (PAL, Pohang, Republic of Korea) using a monochromatic wavelength of 1.4640Å. Diffraction patterns were measured at room temperature from 4° to 124.5° 2θ with a step size 0.005° at a counting time of 1 second per step.

2.6. Single Crystal X-ray Diffraction Single crystals were grown by slow diffusion (diethyl ether/chloroform) from a 1:1 mixture of R and S and then diffraction data was collected on a Bruker D8 QUEST instrument with graphite-monochromated MoKα radiation (λ = 0.71073 Å) under a stream of N2 (g) at 122 K. A half-sphere data collection strategy was designed to provide complete data to a maximum resolution of 0.77 Å over a collection time of ca 3 days. Cell parameters were determined and subsequently refined by SMART.[26] An empirical absorption

ACCEPTED MANUSCRIPT correction was applied using the SADABS program. The structure was solved with Superflip[27] and all nonhydrogen atoms were subjected to anisotropic refinement by full-matrix least-squares on F2 using CRYSTALS.[28] In general, all non-hydrogen atoms were refined with anisotropic displacement parameters. Hydrogen atoms were generally visible in the difference map and their positions and displacement parameters

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were refined using restraints prior to inclusion into the model through riding constraints.

3. Results and discussion

Foldamers composed of 1:1 alternating ACPC and Aib amino acid residues are well known to induce stable 11-helical secondary structure in both the solution state and solid states in foldamers of appropriate length.[25]

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This rigid helical secondary structure and the chirality of each R and S foldamer was confirmed via the CD spectra (Figure S1). Through the co-assembly procedure of these foldamers (described in section 2.3), foldectures in white precipitation form were obtained. Foldectures derived from racemic foldamers (FRS) were

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analysed by SEM and found to have an elongated parallelogram plate shape identical to the previous study—a result consistent with foldecture shape selection being robust and reproducible (Figure 1)[23]. This parallelogram plate shape was obtained when the P123 concentration was greater than 8g/L, with no significant morphological change observed at higher concentrations. Although some fractured structures were observed at low P123 concentration cases, well-defined elongated parallelogram shape of foldectures could not be obtained.

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(Figure S2).

Figure 1. a) Chemical structures of heptameric foldamers R and S. b) Scanning electron microscope image of foldecture derived from racemic foldamers FRS (scale bar = 5 µm).

To analyse the molecular packing structure of FRS, the synchrotron PXRD experiment was carried out (see section 2.5). The resulting diffraction patterns from several independent foldecture self-assembly experiments were combined and normalized to minimize spectral artefacts. Following manual background subtraction, the final pattern was initially indexed to a monoclinic unit cell of dimensions a = 15.0226 Å, b = 18.4178 Å, and c = 18.3303 Å, with α = 90.0°, β = 100.787°, γ = 90.0°, with a volume = 4982.06 Å3.

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Figure 2. a) Preferred orientation approximation of FRS. PMD is the March-Dollase parameter, which indicates that (020) is the principal face. b) Unit cell and molecular packing motif of FRS. c) Intermolecular hydrogen bonding network of R (pink) and S (blue) foldamers, with arrows drawn from N-terminus to C-terminus.

To compensate for systematic errors in peak intensities caused by the non-random orientation of individual foldamers within the powder sample, a March-Dollase preferred orientation model[29] was applied (Figure 2a). Through application of the Bravais-Friedel-Donnay-Harker (BFDH) morphology algorithm[30-32] which predicts crystal morphology using unit cell dimensions and symmetry operators, several families of planes were identified as potentially corresponding to the principal (largest) crystal face. Only refinement with the normal

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vector of the (020) plane produced a value for the March-Dollase preferred orientation parameter less than unity, (PMD value < 1 is indicative of a plate-like morphology), meaning that the principal foldecture face is parallel with the ac plane of the unit cell.

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Rietveld refinement of the initial unit cell (see SI for details) yielded a unit cell of a = 15.00563(15) Å, b = 18.39583(11) Å, c = 18.30721(21) Å, α = γ = 90°, β = 100.8050(10)°, V = 4963.95(8) Å3 and Z = 4 in P21/c, the

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most common centrosymmetric space group in the Cambridge Structural Database.[33] The molecular packing mode is represented in Figure 2b, with crystallographic information and atomic fractional coordinates in Tables S1 and S2, respectively. The final Rietveld plot is represented in Figure S3. A single foldamer constitutes the asymmetric unit, so that the entire unit cell structure is created by operation of the symmetry elements (two-fold screw axes, glide planes and inversions) of the space group; thus, the unit cell contains 4 molecules in total (2 R and 2 S). Each foldamer makes two intermolecular hydrogen bonds with adjacent foldamers of the same chirality through the N and C termini and has lateral hydrophobic interactions with foldamers of both same and opposite chirality, simultaneously. Expansion of the unit cell reveals head-to-tail intermolecular hydrogen bonding between chains of a single enantiomer, with chains of the opposite enantiomer packed in parallel along the ac plain and chains of the same enantiomer packed in antiparallel along the b-axis. In other words, through the FRS molecular packing structure, three intermolecular interactions having different types and orientations were found. (Figure 2c).

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During Rietveld refinement, if instrument parameters and particle size distribution are taken into consideration, anisotropic microstrain within the sample can be calculated from the observed diffraction peak width profiles—anisotropic line broadening. An isosurface for microstrain in FRS calculated using the Stephens model for anisotropic line broadening[34] is shown is Figure 3a, where the x, y, and z axes correspond to the a, b,

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and c axes of the crystal lattice, respectively. Microstrain in the x-axis direction, which is parallel to the set of intermolecular hydrogen bonds that create head-to-tail chains of single enantiomers, is much smaller than those in the other directions. As microstrain correlates with compressibility in a specific direction[35, 36], this result is consistent with the molecular packing supporting a contiguous network of energetically favourable intermolecular hydrogen bonds along the x-axis (Figure 3b). Conversely, microstrain is relatively large along the

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y-axis and z-axis, which support relatively weak intermolecular interactions and are therefore more compressible. However, it is necessary to interpret carefully this result because microstrain may also originate from a

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distribution of dislocations within individual powder grains.

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Figure 3. a) Microstrain isosurface diagram for FRS with axis scales set to δd/d×10–6. b) The unit cell of FRS showing the hydrogen bonding network. The red and light blue dotted lines indicate intermolecular and intramolecular hydrogen bonding, respectively.

The molecular packing modes of enantiopure foldectures and enantiopure single crystals are often significantly different and so in order to compare both foldamer secondary structure and global architecture in a racemic system, single crystals of a 1:1 mixture of R and S were slowly grown through vapor diffusion. To our surprise we found that the single crystal has comparable unit cell dimensions and a unit cell volume only ca 3% smaller than that of the foldecture, a phenomenon likely resulting from cryogenic cooling of the single crystal prior to the x-ray diffraction experiment. The peptide secondary structure is also 11-helical and the space group is P21/c, making the molecular packing motifs nearly spatially identical; an overlay of the architectural unit composed of adjacent R and S foldamers in the single crystal and PXRD structures gives a RMSD of 0.120Å over 48 backbone atoms (Figure 4a, b).

ACCEPTED MANUSCRIPT Based on these results we were able to construct a macroscopic model of FRS (Figure 4c). The principal face (having the largest surface area) was determined to be the (020) plane through preferred orientation analysis, this face was found to be lamellar, with alternately stacked R and S foldamers. Based on the angle between the sides of the parallelograms observed in SEM images, the planes corresponding with the sides of FRS are likely to be the (10-2) and (100). The acute angle of the parallelogram is ca 67º, and the calculated angle between the (10-2) plane and the (100) plane in the molecular packing structure of FRS is 66.72º (Figure 1b). The

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macroscopic view of this model clearly shows how the three types of intermolecular interactions (hydrogen bonding, hydrophobic bonding between different enantiomers and hydrophobic bonding between similar enantiomers) exist in the FRS molecular packing structure. Through this model, we were able to get an intuition

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about the mechanism of the self-assembly process of elongated parallelogram plates.

It is noteworthy that this system exhibits an identical molecular packing mode under both rapid and slow selfassembly regimes—a result infrequently observed in enantiopure foldectures. For instance, in the case of pure S

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the foldecture and single crystal space groups are P32[9] and P1[25], respectively. Based on this result, it may be that racemic self-assembly proceeds through a fundamentally different self-assembly mechanism than enantiopure systems due to strong and spatially matched “lock and key” hydrophobic interaction between enantiomers. The formation of enantiomeric pairs would constitute the initial “nucleation” stage of the selfassembly process, and would then be followed by conventional seeded growth of foldectures (Figure 4 and

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Figure 2c). Studies are currently underway to evaluate this mechanism.

Figure 4. Spatial relationship between enantiomeric pairs in the molecular packing structure of FRS and the single crystal structure. R and S foldamers in the single crystal are coloured green; R and S foldamers in FRS are

ACCEPTED MANUSCRIPT coloured pink and purple, respectively. a) View perpendicular to the ac plane. b) View along the foldamer helical axes. c) Macroscopic model of FRS with indexed faces.

4. Conclusion

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In conclusion, a comprehensive PXRD analysis methodology was employed to elucidate the solid-state structure of a foldecture composed of an equimolar ratio of 11-helical foldamer enantiomers. Foldamers are arranged in a centrosymmetric motif where each foldamer makes two intermolecular hydrogen bonds with two adjacent foldamers of the same chirality, creating head-to-tail chains of a single enantiomer, and has two different lateral hydrophobic interactions with a single foldamer of the opposite and the same chirality. The

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(020) plane was identified with the foldecture principal face and calculation of a microstrain isosurface correlated anisotropic compressibility along with the absolute direction of the head-to-tail intermolecular hydrogen bonding network. Comparison the molecular packing structure of foldecture with the single crystal

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structure found the unit cell dimensions, peptide secondary structure and packing motif to be almost identical, suggesting that enantiomer pairs formed during self-assembly may template the molecular level architecture. The multicomponent assembly strategy can be used for the development of architecturally more complex and heterogeneous organic materials.

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Acknowledgements

This research was supported by National Research Foundation (NRF) of Korea grant funded by the Ministry of Science, ICT, and Future Planning (2016R1A2A1A05005509). High-resolution powder X-ray diffraction pattern for the structure determination process was measured at Pohang Accelerator Laboratory‘s 9B HRPD beamline. The Crystallographic Information File (CIF file) of the co-crystal of R and S was

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submitted to CCDC database with CSD number 1522348.

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[36] A. Honnerscheid, L. van Wullen, R. Dinnebier, M. Jansen, J. Rahmer, M. Mehring, PCCP, 6 (2004) 2454-

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ACCEPTED MANUSCRIPT Supporting information

Structural Analysis of the Foldecture Derived from Racemic Peptide Foldamers

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Jintaek Gong, Jae-Hoon Eom, Rokam Jeong, Russell W. Driver and Hee-Seung Lee*

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Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea

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E-mail: [email protected]

1. Experimental Procedure of Structure Determination from Powder X-ray Diffraction Analysis and Rietveld Refinement

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Diffraction patterns were indexed to a primitive monoclinic unit cell with dimensions a = 15.0226 Å, b = 18.4178 Å, c = 18.3303 Å, α = γ = 90°, β = 100.787°, V = 4982.06 Å3, with Z = 4. Cell parameters were further refined to a = 15.00563(15) Å, b = 18.39583(11) Å, c = 18.30721(21) Å, α = γ = 90°, β = 100.8050(10)°, V = 4963.95(8) Å3, and Z = 4 during the Rietveld refinement (see below). The space group was initially suggested to be P21/c, and was subsequently confirmed during refinement.

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The starting conformation of both R and S were obtained from the racemic single crystal structure (Table S2) and was converted to a Fenske-Hall Z-matrix using OpenBabel software[1]. During conversion, all hydrogen atoms were removed in order to reduce computation time. The F.O.X.[2] program was used to optimize parameters and identify low-cost solutions. During the calculation, the maximum sinθ/λ value was set to 0.25 Å– 1 . All single bonds were allowed to rotate freely, but all bond distances and angles range, including intramolecular hydrogen bonds, were restrained using a Mercury/Mogul Geometry Check[3] against single crystal structures of R; as a delta value, 1.5 times the standard deviation value obtained from the CSD database[4] was used. Anti-bump penalties—designed to avoid abnormally short contact between molecules—were set based on the Van der Waals radii of constituent C, N and O atoms. However, a relatively short anti-bump distance was specified between N and O, which function as acceptor and donor, respectively, in intermolecular hydrogen bonds. A single temperature factor for all atoms in the unit cell was enforced during structure calculation through a Global Biso parameter.

To compensate for anomalous peak intensities resulting from the plate-like morphology of FRS, a March-Dollase preferred orientation approximation[5] was applied. Based on the Bravais–Friedel–Donnay– Harker morphology[6], the March-Dollase parameter (PMD) was refined independently for the normal vectors of S1

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(011), (111), (110), (102), (011), (111), (020), (100) and (110), in order to find the principal face of FRS. Only refinement with the [020] direction corresponding to the normal vector or principal face produced a PMD value < 1, which is indicative of a plate-like morphology.

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Parallel tempering[7] through grid computation was selected as the method for global optimization; more than 10,000,000 cycles of computation were carried out per structure solution. Among valid structure solutions (typically 20-30 per trial), the structure having the lowest-cost solution was subjected to Rietveld refinement. Rietveld refinement was carried out using GSAS[8] with the graphical user interface system EXPGUI.[9] Diffraction pattern regions below 7° and above 60° (in 2θ, dmin = 1.464 Å) were excluded from refinement due to low signal-to-noise ratio. All hydrogen atoms were omitted. All bond distances including intramolecular hydrogen bonds and bond angles were subjected to restraints (see above). All amides, a carbamate, an ester and an aromatic ring were restrained to a planar geometry and remained in place throughout the refinement. The restraints contributed 6.84% to the final χ2.

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A single isotropic thermal displacement factor (Uiso) value was applied for all atoms in the unit cell. Stephens anisotropic strain broadening model[10] and Finger-Cox-Jephcoat model[11] were adopted to describe peak shapes. The background was fitted and refined with a twenty-term shifted Chebyshev polynomial. The final refinement step yielded the residual difference Rp = 8.12%, Rwp = 11.1% and goodness of fit S = 1.90. The final Rietveld plot is represented in Figure S2.

S2

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2. Characterization Results

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Figure S5. Circular Dichroism spectra of foldamers R and S in MeOH at 22℃.

Figure S6. Scanning electron microscopy images showing the relationship between foldecture morphology and P123 concentration. a) 0 g/L, b) 1 g/L, c) 4 g/L, d) 8 g/L, e) 16 g/L, f) 24 g/L, g) 32 g/L and h) 48 g/L of P123 aqueous solution. (Scale bar = 5 µm).

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Figure S7. Rietveld plot for the molecular packing structure of FRS. Red crosses represent observed data points, and the green line is the calculated diffraction pattern. The magenta curve indicates the difference between observed and calculated data points. Black tick marks represent the positions of individual reflections. The vertical axis is square-root scale in order to show clearly high-angle data.

Table S1. Crystallographic information for FRS. Crystal data Chemical formula*

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Mr*

C46N7O10

Crystal system, space group

Monoclinic, P21/c

Temperature (K)

298

15.00563(15), 18.39583(11), 18.30721(21)

α, β, γ (°)

90, 100.8050(10), 90

3

V (Å ) Z

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a, b, c (Å)

4963.95(8) 4

Radiation type

Synchrotron radiation (λ=1.4640Å)

Specimen form, colour

Powder (particle morphology: small parallelogram plate), white

Specimen preparation temperature

Room temperature

Data collection Diffractometer

9B High-resolution powder diffraction beamline at Pohang S4

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Specimen mounting: zero-background silica holder, Mode: reflection mode in Bragg-Brentano geometry, Step scan method 2θmin = 7, 2θmax = 60, increment = 0.01

2θ (°, range in Refinement)

Refinement Intensities

Least-squares matrix

Full-matrix

R factors and goodness-of-fit

Rp = 0.0812, Rwp = 0.1110, Rexp = 0.0606, R(F2) = 0.11185, S = 1.90

Excluded region(s)

18.190° – 18.255° in 2θ

Profile function

No. of parameters

CW Profile function number 4 with 21 terms. Pseudo-voigt profile coefficients as parameterized in Thompson et al. (1987). Asymmetry correction of Finger et al. (1994). Microstrain broadening by Stephens (1999). #1(GU) = 0.000, #2(GV) = 0.000, #3(GW) = 0.000, #4(GP) = 1.171, #5(LX) = 0.000, #6(ptec) = 0.00, #7(trns) = 4.34, #8(shft) = -0.2712, #9(sfec) = 0.00, #10(S/L) = 0.0115, #11(H/L) = 0.0115, #12(eta) = 1.0000, #13(S400) = 1.6×10-3, #14(S040) = 3.5×10-3, #15(S004) = 5.1×10-3, #16(S220) = 2.6×10-3, #17(S202) = 1.2×10-3, #18(S022) = -1.1×10-3, #19(S301) = -1.9×10-3, #20(S103) = 5.0×10-3, #21(S121) = -4.5×10-4. Peak tails are ignored where the intensity is below 0.0040 times the peak. Anisotropic broadening axis 0.0 0.0 1.0. 230

No. of restraints

192

No. of data points

10601

GSAS background function number 1, Shifted Chebyshev function with twenty terms. 1: 172.604, 2: -135.530, 3: 89.3500 ,4: -60.1745, 5: 27.2826, 6: -17.7867, 7: 11.7611, 8: -4.98886, 9: 4.12786, 10: 1.52953, 11: -2.73192, 12: 2.84737, 13: -2.86175, 14: -0.537953, 15: 2.54523, 16: -1.42045, 17: 0.627482, 18: 0.844309, 19: -0.497130, 20: 5.412030×10-3. 0.05, 0.00

AC C

(∆/σ)max, (∆/σ)mean

TE D

Background function

Omitted during the refinement process

EP

H-atom treatment*

M AN U

SC

RI PT

Refinement on

* H-atoms were omitted during the structure determination process.

S5

ACCEPTED MANUSCRIPT Table S2. Atomic fractional coordinates, thermal isotropic displacement parameters (Uiso), occupancy, and multiplicity of FRS foldecture. x

y

z

Uiso(Å2)

O1

0.5673(4)

0.7013(4)

0.2638(5)

C2

0.6363(4)

0.72365(30)

N3

0.6907(4)

C4

Multiplicity

0.0550(8)

1

4

0.30433(29)

0.0550(8)

1

4

0.77248(35)

0.28012(31)

0.0550(8)

1

4

0.65984(31)

0.81741(24)

0.21441(26)

0.0550(8)

1

4

C5

0.62406(29)

0.89236(25)

0.23438(27)

0.0550(8)

1

4

C6

0.52093(25)

0.8904(5)

0.23124(22)

0.0550(8)

1

4

O7

0.4662(4)

0.8967(6)

0.1719(4)

0.0550(8)

1

4

N8

0.49272(33)

0.8751(5)

0.29603(28)

0.0550(8)

1

4

C9

0.39684(29)

0.87615(26)

0.30395(26)

0.0550(8)

1

4

C10

0.3421(4)

0.82232(26)

0.24900(33)

0.0550(8)

1

4

O11

0.2760(5)

0.8443(4)

0.20600(31)

0.0550(8)

1

4

N12

0.3816(4)

0.76025(29)

0.23659(35)

0.0550(8)

1

4

C13

0.3380(4)

0.70721(23)

0.18206(24)

0.0550(8)

1

4

C14

0.3751(4)

0.70820(23)

0.10822(24)

0.0550(8)

1

4

C15

0.3249(4)

0.76147(21)

0.05063(28)

0.0550(8)

1

4

O16

0.2650(6)

0.74057(35)

-0.0008(5)

0.0550(8)

1

4

N17

0.3610(5)

0.82702(28)

0.04851(32)

0.0550(8)

1

4

C18

0.32560(31)

0.88093(25)

-0.00871(25)

0.0550(8)

1

4

C19

0.22177(31)

0.8979(5)

-0.01076(25)

0.0550(8)

1

4

O20

0.1748(6)

0.9203(5)

-0.0692(4)

0.0550(8)

1

4

N21

0.18895(34)

0.8977(4)

0.05450(23)

0.0550(8)

1

4

C22

0.09174(30)

0.90070(26)

0.05854(26)

0.0550(8)

1

4

C23

0.05262(30)

0.82382(26)

0.06573(25)

0.0550(8)

1

4

C24

0.01199(25)

0.7915(4)

-0.00996(24)

0.0550(8)

1

4

O25

-0.0688(4)

0.7958(5)

-0.0353(5)

0.0550(8)

1

4

N26

0.0702(4)

0.7648(5)

-0.05066(28)

0.0550(8)

1

4

C27

0.03955(35)

0.73943(29)

-0.12695(25)

0.0550(8)

1

4

-0.0408(4)

0.6903(4)

-0.1291(4)

0.0550(8)

1

4

-0.1094(6)

0.7005(5)

-0.1728(6)

0.0550(8)

1

4

-0.0292(5)

0.63739(35)

-0.0776(5)

0.0550(8)

1

4

-0.10594(34)

0.58730(34)

-0.0795(5)

0.0550(8)

1

4

C32

-0.09020(25)

0.51170(23)

-0.11065(26)

0.0550(8)

1

4

C33

-0.08001(30)

0.45013(27)

-0.06506(27)

0.0550(8)

1

4

C34

-0.0659(4)

0.38196(25)

-0.09366(30)

0.0550(8)

1

4

C35

-0.06186(31)

0.37376(27)

-0.16799(32)

0.0550(8)

1

4

C36

-0.07182(33)

0.43322(29)

-0.21395(27)

0.0550(8)

1

4

O29 O30 C31

SC

M AN U

TE D

EP

AC C

C28

RI PT

Occupancy

S6

ACCEPTED MANUSCRIPT x

y

z

Uiso(Å2)

C37

-0.08607(32)

0.50175(26)

-0.18587(28)

C38

0.1142(6)

0.6956(5)

C39

0.0102(8)

C40

Multiplicity

0.0550(8)

1

4

-0.1532(6)

0.0550(8)

1

4

0.8040(4)

-0.1786(6)

0.0550(8)

1

4

-0.0140(5)

0.8303(4)

0.1206(4)

0.0550(8)

1

4

C41

-0.0100(6)

0.9073(5)

0.1467(7)

0.0550(8)

1

4

C42

0.0737(6)

0.9413(4)

0.1277(4)

0.0550(8)

1

4

C43

0.3377(8)

0.8501(5)

-0.0840(4)

0.0550(8)

1

4

C44

0.3786(7)

0.9520(4)

0.0072(7)

0.0550(8)

1

4

C45

0.3654(10)

0.62978(33)

0.0809(4)

0.0550(8)

1

4

C46

0.3519(8)

0.62944(31)

0.2116(4)

0.0550(8)

1

4

C47

0.3869(9)

0.8556(5)

0.3836(4)

0.0550(8)

1

4

C48

0.3597(8)

0.9529(4)

0.2846(7)

0.0550(8)

1

4

C49

0.6560(6)

0.9472(4)

0.1795(4)

0.0550(8)

1

4

C50

0.6986(8)

0.9003(5)

0.1258(6)

0.0550(8)

1

4

C51

0.7332(4)

0.8345(4)

0.1688(4)

0.0550(8)

1

4

C52

0.67639(32)

0.67959(23)

0.37429(27)

0.0550(8)

1

4

N53

0.7230(4)

0.72791(27)

0.43440(29)

0.0550(8)

1

4

C54

0.68304(31)

0.78745(24)

0.45782(24)

0.0550(8)

1

4

O55

0.6156(5)

0.8156(4)

0.4249(4)

0.0550(8)

1

4

O56

0.7338(4)

0.81400(29)

0.5210(4)

0.0550(8)

1

4

C57

0.7050(4)

0.87776(31)

0.55964(34)

0.0550(8)

1

4

C58

0.6830(11)

0.9382(6)

0.5039(7)

0.0550(8)

1

4

C59

0.7812(8)

0.8989(7)

0.6218(7)

0.0550(8)

1

4

C60

0.6240(7)

0.8509(7)

0.5893(7)

0.0550(8)

1

4

C61

0.6008(6)

0.6376(5)

0.4018(6)

0.0550(8)

1

4

C62

0.7428(6)

0.6257(5)

0.3503(6)

0.0550(8)

1

4

C63

0.3791(13)

0.5857(4)

0.1506(6)

0.0550(8)

1

4

SC

M AN U

TE D

AC C

EP

RI PT

Occupancy

S7

ACCEPTED MANUSCRIPT Table S3. Hydrogen bonds in FRS foldecture.

SC

Table S4. Single Crystal X-ray Structure of the co-crystal of R and S.

D-H…A (°) 167.18 147.71 151.67 149.78 168.24 157.07 160.56

RI PT

Type D-H (Å)* H…A (Å) D…A (Å) D-H…A N8-H81…O55 Intramolecular 0.861 2.076 2.922 N12-H121…O1 Intramolecular 0.860 2.181 2.944 … N17-H171 O7 Intramolecular 0.860 2.024 2.811 N21-H211…O11 Intramolecular 0.860 2.226 3.001 … N26-H261 O16 Intramolecular 0.860 2.081 2.928 N53-H531…O25 Intermolecular 0.860 2.289 3.100 N3-H31…O29 Intermolecular 0.860 2.178 3.003 * Hydrogens attached to N in amide groups were added manually, considering its geometry.

AC C

Crystal data

EP

TE D

M AN U

The Crystallographic Information File (CIF file) of the co-crystal of R and S was submitted to CCDC database with CSD number 1522348.

C46 H71 N7 O10

V = 4850.2 (3) Å3

Mr = 1764.23

Z=4

Monoclinic, P21/c

Mo Kα radiation

a = 14.9209 (11) Å

m=0.09 mm−1

b = 18.2546 (13) Å

T = 115 K

c = 18.1382 (13) Å

0.2 x 0.4 x 0.4mm

β = 100.9665 (16)°

block S8

ACCEPTED MANUSCRIPT

Bruker D8 Quest

Rint = 0.071

219765 measured reflections

θmax = 27.6°

11203 independent reflections

9385 reflections with I > 2.0σ(I)

Refinement

RI PT

Data collection

31 restraints

wR(F2) = 0.185

H atoms treated by a mixture of independent and constrained refinement

S = 1.06

∆ρmax = 0.54 e Å−3

11142 reflections, 598 parameters

∆ρmin = −0.57 e Å−3

M AN U

References

[7]

[8] [9] [10] [11]

TE D

[4] [5] [6]

EP

[2] [3]

N. O’Boyle, M. Banck, C. James, C. Morley, T. Vandermeersch, G. Hutchison, J Cheminform 2011, 3, 1-14. V. Favre-Nicolin, R. Cerny, J. Appl. Crystallogr. 2002, 35, 734-743. aI. J. Bruno, J. C. Cole, M. Kessler, J. Luo, W. D. S. Motherwell, L. H. Purkis, B. R. Smith, R. Taylor, R. I. Cooper, S. E. Harris, A. G. Orpen, Journal of Chemical Information and Computer Sciences 2004, 44, 2133-2144; bR. A. Sykes, P. McCabe, F. H. Allen, G. M. Battle, I. J. Bruno, P. A. Wood, J. Appl. Crystallogr. 2011, 44, 882-886. C. R. Groom, I. J. Bruno, M. P. Lightfoot, S. C. Ward, Acta Crystallogr. Sect. B 2016, 72, 171-179. W. A. Dollase, J. Appl. Cryst. 1986, 19, 267-272. aA. Bravais, Études cristallographiques par M. Auguste Bravais, Gauthier-Villars, 1866; bM. Friedel, Bull. Soc. Franc. Miner 1907, 9, 326; cJ. D. H. Donnay, D. Harker, Am. Mineral. 1937, 22, 446-467. aV. Favre-Nicolin, R. Černý, Zeitschrift für Kristallographie/International journal for structural, physical, and chemical aspects of crystalline materials 2004, 219, 847-856; bR. Cerny, V. FavreNicolin, Powder Diffr 2005, 20, 359-365; cR. Černý, V. Favre-Nicolin, Zeitschrift für Kristallographie 2007, 222, 105-113. A. C. Larson, R. B. V. Dreele, General Structure Analysis System (GSAS), Los Alamos National Laboratory Report LAUR 86-748, 2004. B. H. Toby, J. Appl. Crystallogr. 2001, 34, 210-213. P. Stephens, J. Appl. Cryst. 1999, 32, 281-289. L. W. Finger, D. E. Cox, A. P. Jephcoat, J. Appl. Crystallogr. 1994, 27, 892-900.

AC C

[1]

SC

R[F2 > 2σ(F2)] = 0.072

S9

ACCEPTED MANUSCRIPT Research Highlights for,

Structural Analysis of the Foldecture Derived from Racemic Peptide Foldamers

RI PT

Jintaek Gong, Jae-Hoon Eom, Rokam Jeong, Russell W. Driver and Hee-Seung Lee*

Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea

M AN U

SC

E-mail: [email protected]

1. The first example of the molecular packing structure of foldecture composed of multiple components was reported.

2. The anisotropic microstrain analysis revealed the intermolecular interactions of racemic foldamers along with their orientations.

3. The formation of enantiomeric pairs was proposed in the initial nucleation stage of the

AC C

EP

TE D

self-assembly process.