Introduction

Chirality is a ubiquitous fundamental property in nature and plays a crucial role in chemistry, biology, materials science and physics1,2,3,4. In biological systems, chiral molecules connect sequentially to form macromolecules by selecting homochiral molecules and further fabricate higher-ordered helical nanostructures such as double-helical DNA and α-helical proteins5,6, in which the chirality was transferred from molecules to higher-level structures with the conservation of molecular chirality7,8,9,10,11,12,13,14,15,16. In materials systems, it is found that two pathways can direct the formation of macroscopic chiral morphologies or shapes. One is the small chiral molecules such as amino acids, peptides and chiral ligands, which can be associated with selective growth of certain facets and the breaking of intrinsic crystal symmetry17,18,19,20,21,22,23,24,25,26,27. The other is the screw dislocations or chiral topological defects, which have been proven to be an important way of fabricating one-dimensional (1D)28,29,30,31,32,33,34 and two-dimensional (2D)35,36,37,38,39,40 materials with macroscopic chiral shapes. In particular, they will possibly cause the curvature in crystals and drive the formation of mesoscale twisted crystals32 or supertwisted spiral crystals41 on non-Euclidean surfaces42. In addition, screw dislocation is also a classical method for producing three-dimensional (3D) spirals from inorganic crystals and polymers43. However, 3D helicoid structures rarely originate from small organic molecules. In macroscopic particle systems, the helical hexagonal crystals assembled by 1 μm long filamentous viruses via screw dislocations with the chiral transfer from particles to helical superstructures were found44. However, such cross-length scale transfer of macroscopic chirality7 induced by screw dislocations in supramolecular systems is still relatively rare37. Especially, although many chiral structures such as helix and twist7,8, have been reported, the formation of the nano/microstructure beyond Euclidean geometry42 is still a great challenge.

Here, we propose a hierarchical self-assembly strategy based on screw dislocations to construct a macroscopic 3D helicoid with strong circularly polarized luminescence (CPL)45,46,47. The helicoid is the only ruled minimal surface other than the plane and has less been reported through self-assembly. The electron-deficient chiral pyromellitic diimide-based molecular triangle (PMDI-Δ) with rigid π-conjugated aromatic linkers was co-assembled with an achiral pyrene to form intermolecular charge transfer (CT) complexes48,49,50 by a thermal annealing process (Figs. 1a-c). Helical twists emerged with pyrene sandwiching into adjacent PMDI-Δ via π-π stacking and CT interactions. The CT complexes grew into a curved microsheet as a subunit due to helical growth around a screw dislocation. Layer-by-layer screw dislocations drove the formation of macroscopic homochiral helicoids via efficient chirality transfer (Fig. 1b). These helicoids showed a pronounced macroscopic helicity controlled by the molecular chirality of PMDI-Δ and exhibited excellent CPL properties. This work demonstrated the transmission and expression of chirality at molecular, supramolecular, and macroscopic levels.

Fig. 1: Hierarchical co-self-assembly of homochiral helicoids.
figure 1

a Molecular structures of R-PMDI-Δ, S-PMDI-Δ and Pyrene, respectively. b Transmission and expression of chirality across different length scales at molecular, supramolecular and macroscopic levels. c Photographs of sample vials in different assembly stages under natural light correspond to before annealing, annealing at 140 °C, and after annealing from left to right, respectively. d to f and h SEM images of (d) R-PMDI-Δ/Pyr helicoidsDMF, (e and h) S-PMDI-Δ/Pyr helicoidsDMF and (f) rac-PMDI-Δ/Pyr co-assembliesDMF. g Fluorescence microscopy image of R-PMDI-Δ/Pyr helicoidsDMF. i Statistical analysis of the length and width of helicoidsDMF.

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Results

Self-assembly of homochiral helicoids

The rigid chiral PMDI-Δ macrocycle51,52 (Fig. 1a and Supplementary Fig. 1) with electron deficiency was selected as an electron acceptor and the size-matched electron-rich pyrene (Pyr) was selected as an electron donor. In a typical co-assembly protocol (Supplementary Fig. 2), the PMDI-Δ and Pyr were dissolved in DMF by ultrasound to give a transparent solution. Water was added as the anti-solvent to provide a homogeneous yellow suspension, which was then annealed at 140 °C for 10 minutes until the charge-transfer (CT) complex between the two molecules was broken and the yellow color of the suspension completely faded. The subsequent natural cooling of the suspension to room temperature facilitated the co-assembly, which could be distinctly observed with the naked eye due to dramatic color changes (Fig. 1c and Supplementary Fig. 3a). The self-assemblies of both PMDI-Δ and Pyr were white, whereas the co-assemblies presented a yellow color under natural light due to CT complex formation after annealing (Supplementary Fig. 3). The morphology of co-assemblies obtained after annealing was observed by scanning electron microscopy (SEM), in which unique micrometer-sized homochiral helicoids were visualized (Figs. 1d, e, h and Supplementary Fig. 4), while individual PMDI-Δ or Pyr could only form achiral nanostructures (Supplementary Fig. 5). The SEM images showed that the size of helicoids was relatively uniform (Fig. 1h). Statistical analysis gives an average length of 15.76 ± 3.44 μm and an average width of 9.73 ± 1.90 μm (Fig. 1i, Supplementary Fig. 6 and Supplementary Table 1). The fluorescence microscope images also revealed that the size of helicoids was about a dozen micrometers (Fig. 1g). Intriguingly, when R-PMDI-Δ and Pyr were employed, a left-handed (M-helical) helicoid was obtained (Fig. 1d and Supplementary Fig. 4a), while S-PMDI-Δ/Pyr co-assemblies showed a right-handed (P-helical) one (Fig. 1e and Supplementary Fig. 4b). This demonstrated that the macroscopic helicity of the helicoids was determined by the molecular chirality of PMDI-Δ. In comparison, when racemic PMDI-Δ and Pyr were co-assembled, it was observed that microsheets twisted in two opposite directions and were piled up on each other, indicating the self-sorting of the PMDI-Δ racemate triggered by Pyr (Fig. 1f and Supplementary Fig. 7). Morphological observations revealed that other electron donors with various sizes different from Pyr could not co-assemble into any chiral nanostructures with PMDI-Δ, which suggested the necessity of size matching between PMDI-Δ and Pyr for the formation of helicoids (Supplementary Figs. 8 to 9). The amount of Pyr added and the ratio of DMF and H2O were found to affect the macroscopic morphology of the co-assemblies as well (Fig. 2a and Supplementary Fig. 10). It should be noted that while mixed solvents such as THF/H2O and dioxane/H2O could not afford the helicoids (Supplementary Fig. 11), the morphology of the co-assemblies obtained in NMP/H2O was similar to that obtained in DMF/H2O (Supplementary Fig. 12), except that a fully-formed S-type double helicoid (for R-PMDI-Δ/Pyr) and an anti-S-shaped double helicoid (for S-PMDI-Δ/Pyr) could also be observed in NMP/H2O (Figs. 2b to d and Supplementary Fig. 13). Interestingly, in DMF/H2O, only two helicoids side by side were observed, but they could not be completely connected and grow to form a whole structure (Supplementary Fig. 14). By successfully capturing the initial morphology of helicoids and double helicoids in NMP/H2O, a possible formation mechanism for both types of helicoids was proposed (Fig. 2e and Supplementary Fig. 15). The process involved the layer-by-layer stacking of chiral subunits, which led to the formation of helicoids. However, some chiral microsheets could be connected side-by-side while stacking layer-by-layer, which led to the co-assemblies growing in two directions, thus forming a double helicoid structure by two helicoids connecting side-by-side. The formation of complete double helicoids in NMP/H2O could be attributed to the lower polarity and the higher viscosity of NMP compared with DMF (Supplementary Table 2). These two factors enhanced intermolecular CT interactions between PMDI-Δ and Pyr and gave rise to a more stable dispersion of chiral subunits in the solution, which enabled the connection of side-by-side and facilitated double helicoids formation.

Fig. 2: Morphology evolution and structure analysis of homochiral helicoids.
figure 2

a Typical SEM images of R-PMDI-Δ/Pyr co-assembliesDMF with different molar equivalent Pyr. b SEM images of helicoidsNMP and S-type double helicoidsNMP (for R-Δ/Pyr). c, d SEM images of anti-S-shaped double helicoidsNMP (for S-Δ/Pyr), from top view (c) and side view (d). e Formation mechanism of helicoidsNMP and double helicoidsNMP. f, g SEM images and corresponding cartoon representations of typical R-PMDI-Δ/Pyr helicoidsDMF and its subunits. h–k Screw dislocations model analysis. h Magnified view of the edge region of the R-Δ/Pyr helicoidsDMF shown in Fig. 1d, in which the tangents to the edges of layered subunits were highlighted with solid white line. i Scatter plot and linear fitting curve of the evolving twist angles θ in (h) as a function of layer number counted from the bottom to the top. The average of θ is equal to 16.9° and the coefficient of determination R2 was equal to 0.97. j The 3D AFM morphology image of the edge of R-Δ/Pyr helicoidDMF, as denoted by the red box in Supplementary Fig. 17a. k The height profile across the blue line in (j). l SEM images of R-PMDI-Δ/Pyr co-assembliesDMF before annealing and with different natural cooling times after annealing. Scale bars, 5 μm (a) and 2 μm (b to e and l).

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Screw dislocations analysis of homochiral helicoids

It was revealed that the formation of hierarchically self-assembled homochiral helicoids was associated with the growth of chiral subunits driven by screw dislocations. Taking R-PMDI-Δ/Pyr helicoids formed in DMF/H2O as an example, as shown in Fig. 2f, the CT assemblies of R-PMDI-Δ and Pyr firstly grew into a curved microsheet as the subunit due to M-helical growth around a screw dislocation (Figs. 2f, g and Supplementary Fig. 16). SEM images showed that the arc-shaped curved subunits arranged in a helical pattern around a center by each upper layer twisting and gathering toward the center based on the lower layer (Fig. 2h), which indicated that new screw dislocations sites continuously generated on the surface of the lower layer and successively created new layers. This self-perpetuating growth step advanced the macroscopic twist level of the co-assemblies and resulted in a twist angle θ between adjacent layers (Fig. 2h). We measured the twist angle θ and counted the layer number. An approximately linear relationship between the twist angle θ and the layer number was found and the linear fittings showed an average twist of 16.9° per layer (Fig. 2i), which proved that the growth evolution mechanism of helicoids conformed to the screw dislocations model32,41. Atomic force microscope (AFM) was performed to provide height information of helicoids and further insights into the possible assembly mechanism (Figs. 2j, k, Supplementary Figs. 17 and 18). The AFM images revealed the 3D morphology with a height at the micrometer level, helical arrangement and left-handed helicity (M-helicity) of R-Δ/Pyr helicoidsDMF (Supplementary Fig. 17). The characterization of the edge height of the helicoidsDMF showed the same screw dislocation features as observed in the SEM images, that is, the nanosheets with a thickness of ca. 41-61 nm continuously generated twisted stacking toward the center (Figs. 2j and k). The AFM images of the R-Δ/Pyr helicoidsNMP also exhibited similar results (Supplementary Fig. 18).

The SEM was used to monitor the evolution of helicoidsDMF by separating precipitates at different stages of assembly. The sample without annealing after anti-solvent assembly showed a hexagonal tubular structure without macroscopic chirality (Fig. 2l and Supplementary Fig. 19). After thermal annealing, nanosheets smaller than 1 μm were formed as the substrates for the growth of chiral microsheet subunits. It could be found after natural cooling for 2 minutes, some circular microsheets with arc-shaped curved subunits at the edge were produced. The size of the assemblies increased with the prolonging of cooling time. After cooling for 10 minutes, the size of the assemblies reached about 10 μm. It was worth noting that for these samples with a cooling time of 5–10 minutes, a slightly twisted helicoidDMF with macroscopic left-handedness was observed and similar structures could also be observed in helicoidsNMP (Supplementary Fig. 20). These structures displayed cyclic subunits on the edges of the nearly circular bottom. These features were consistent with the growth model driven by screw dislocations29,37,44,53. After natural cooling for 30 minutes, a fully twisted left-handed helicoid was formed (Fig. 2l), while further elongation of the time did not cause further growth of the helicoids.

Single-crystal structures

To gain deeper insights into the CT interaction between PMDI-Δ and Pyr and the origin of the macroscopic chiral morphology, we first cultivated a single crystal of R-PMDI-Δ (Supplementary Fig. 21 and Supplementary Table. 3) and a cocrystal of R-PMDI-Δ and Pyr (Supplementary Fig. 22 and Supplementary Table. 4) in DMF/H2O mixed solvents by a heating-cooling method similar to self-assembly. The R-PMDI-Δ single crystal showed a triclinic structure with a P1 feature of the chiral space group. The adjacent molecules displayed π-π stacking and multiple C-H···O interactions with the distance of 3.21-3.34 Å and 2.53-2.69 Å, respectively (Fig. 3b). A two-dimensional (2D) supramolecular pattern was formed in the a-b plane (Fig. 3c), which was stacked into a layered structure along the c-axis (Supplementary Fig. 23). It was worth noting that although R-PMDI-Δ was a chiral molecule, no twisted helical structures were formed in its crystal due to the close face-to-face arrangement of the two adjacent molecules (Fig. 3a), which could be responsible for the formation of achiral nanostructures observed in PMDI-Δ assemblies.

Fig. 3: Single-crystal structures.
figure 3

a–c Single crystal structures of R-PMDI-Δ. a, b The untwisted structure formed by π-π stacking and C-H···π interactions in two adjacent molecules. c The 2D supramolecular structure formed by R-PMDI-Δ in the a-b plane. d–i The structure of R-PMDI-Δ/Pyr cocrystalDMF. d The π-π stacking and C-H···π interactions in an ADA sandwich. e The C-H···π interactions and (f) the C-H···O interactions in two adjacent ADA sandwiches. g Crystal structure illustrating adjacent ADA sandwiches showed supramolecular M-helix by C-H···π interaction. h 2D supramolecular tiling formed by ADA sandwichs in the b-c plane. i Layered stacking structure along the a-axis. j–l The R-PMDI-Δ/Pyr cocrystalNMP showed a similar structure to cocrystalDMF, including the ADA sandwichs (j) with supramolecular M-helix (k) and 2D supramolecular structure (l). For clarity, solvent molecules are omitted. Except for the panels (a, b, d, e, f and j), H atoms are omitted in other panels.

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Single-crystal X-ray analysis indicated that R-PMDI-Δ/Pyr cocrystalDMF adopted the monoclinic chiral space group C2 with an acceptor to donor ratio of 2:1. Interestingly, two electron acceptors R-PMDI-Δ with symmetry equivalence and one electron donor Pyr formed a twisted acceptor-donor-acceptor structure (ADA sandwich) through π-π stacking and C-H···π interaction, where the distance of π-π stacking ranged from 3.19 to 3.35 Å and that of C-H···π interaction was 2.74 Å (Fig. 3d). The dihedral angle α between two PMDI-Δ molecule planes in an ADA sandwich was 46.6° or 42.6° (Supplementary Fig. 24). The same ADA sandwiches form M-helical 1D supramolecular co-assemblies through C-H···π interactions between R-PMDI-Δ in the way of vertex-to-edge (the distance of C-H···π is 2.81 Å) (Figs. 3e and g). This result indicated that R-PMDI-Δ/Pyr cocrystalDMF showed chirality at the supramolecular level, which provided a prerequisite for the formation of macroscopic chiral shapes of co-assemblies54. The 1D supramolecular co-assemblies formed 2D supramolecular tiling structures in the b-c plane through C-H···O interactions between R-PMDI-Δ (The distance of C-H···O was 2.45-2.72 Å) (Figs. 3f and h), which further stacked into layered structures along the a-axis (Fig. 3i).

Fortunately, by slowly evaporating water into the NMP solution mixed with R-PMDI-Δ and Pyr, we also obtained the R-PMDI-Δ/Pyr cocrystalNMP (Supplementary Fig. 25 and Supplementary Table. 5), which displayed a similar composition and structure to cocrystalDMF. For example, it also crystallized in the monoclinic C2 chiral space group, and also formed ADA sandwiches (Fig. 3j), M-helical CT co-assemblies (Fig. 3k) and supramolecular tiling structures (Fig. 3l). However, the dihedral angle α of cocrystalNMP was 45.8° and 41.5°, which was slightly smaller than that of cocrystalDMF (Supplementary Fig. 24). In addition, the crystal structures showed that solvent DMF or NMP formed hydrogen bonds with H2O in the intrinsic pore of the R-PMDI-Δ (Supplementary Fig. 26). This result indicated that the hydrogen bonds played an important role in supramolecular co-assembly in the present systems.

Chiroptical properties of homochiral helicoids

The absorption spectra of PMDI-Δ, Pyr and co-assemblies were shown in Fig. 4a. The helicoidsDMF and helicoidsNMP displayed a wide absorption band ranging approximately from 383-500 nm and 381-510 nm, respectively, which confirmed the intermolecular CT interaction between PMDI-Δ and Pyr and the formation of the CT complexes. The optical bandgaps for helicoids could be calculated from the edge of the absorption spectra. The results revealed that the bandgap for helicoidsDMF was 2.50 eV and that for helicoidsNMP was 2.46 eV. Density functional theory (DFT) calculations for the frontier molecular orbitals of CT-complexes of PMDI-∆ and Pyr showed that the highest occupied molecular orbitals (HOMO) of CT-complexes were mainly concentrated on electron donor Pyr and the lowest unoccupied molecular orbitals (LUMO) were mainly located on the electron-deficient PMDI-Δ (Supplementary Fig. 27). The calculated HOMO-LUMO energy gaps of CT-complexDMF and CT-complexNMP were 2.63 eV and 2.67 eV, respectively, which were consistent with their optical bandgaps. Distinct from individual Pyr or PMDI-Δ assemblies, the co-assemblies exhibited visible bright green fluorescence under 365 nm UV light (Supplementary Figs. 3b-c). The fluorescence spectra showed Pyr displayed monomer emission peaks at 368 nm and 397 nm and PMDI-Δ showed monomer emission peaks at 413 nm in DMF solution (Fig. 4d), while the co-assemblies clearly showed a red-shifted CT emission peak. The maximum emission of helicoidsDMF was 533 nm and that of helicoidsNMP was 539 nm, which red-shifted by 120 nm and 126 nm relative to the PMDI-Δ monomer, respectively (Fig. 4d).

Fig. 4: Chiroptical properties of homochiral helicoids.
figure 4

a UV–Vis absorption spectra of Pyr powder, R-PMDI-Δ self-assemblies and PMDI-Δ/Pyr co-assemblies. b and c CD spectra of co-assemblies. d Normalized fluorescence spectra of Pyr monomer, R-PMDI-Δ monomer and co-assemblies. [Pyrene] = [R-PMDI-Δ] = 0.1 mM, the solvent is DMF. e, f CPL spectra of co-assemblies. The λex used for fluorescence and CPL measurements of co-assemblies is 365 nm. The λex used for fluorescence measurements of Pyr monomer and R-PMDI-Δ monomer is 300 nm.

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The R-PMDI-Δ/Pyr helicoidsDMF showed a positive CD signal over 400 nm corresponding to the CT absorption band of helicoidsDMF. A mirrored CD signal was found for the S-PMDI-Δ/Pyr helicoidsDMF (Fig. 4b and Supplementary Fig. 28). Compared with the PMDI-Δ monomer (Supplementary Fig. 29), the CD signal displayed an obvious red shift, which indicated that the molecular chirality of PMDI-Δ had been transferred to CT co-assemblies. Similar but stronger CD signals (Fig. 4c and Supplementary Fig. 28) as well as higher |gabs| values were recorded for helicoidsNMP (Supplementary Fig. 30). Circularly polarized luminescence (CPL) was carried out to study the excited state chirality of co-assemblies. The CPL signal of PMDI-Δ self-assemblies was not detected due to their weak luminescent properties (Supplementary Fig. 31). However, the PMDI-Δ/Pyr co-assemblies not only expressed macroscopic helical chirality but also exhibited excellent CPL properties. The intense and mirrored CPL signals were detected in both co-assemblies (Figs. 4e, f and Supplementary Fig. 32). As an important parameter to evaluate CPL, the dissymmetry factor |glum| was found to reach 0.050 for helicoidsNMP (Supplementary Fig. 33). The helicoidsDMF also showed a high |glum| value of 0.026 (Supplementary Fig. 33). Furthermore, the CT co-assemblies without macroscopic chirality prepared by annealing in either THF/H2O or dioxane/H2O did not exhibit CT-CPL signals (Supplementary Fig. 34), indicating a strong correlation between chiral helical structures and chiroptical properties. The photophysical properties of co-assemblies were summarized and shown in Supplementary Table 6.

Self-assembly mechanism of homochiral helicoids

It should be noted that a series of experimental results had shown that the composition and structure of helicoids obtained after annealing were consistent with the corresponding cocrystals except for the emergence of unique screw dislocations in the helicoids. Firstly, the 1H-NMR spectra showed that the molar ratio of PMDI-Δ and Pyr in the helicoids was very close to 2:1 (Supplementary Fig. 35 and Supplementary Table 7), whether in DMF/H2O or NMP/H2O. This was in agreement with the ratio of the two molecules in the cocrystals. Moreover, the powder X-ray diffraction (PXRD) patterns of the helicoids were consistent with simulated XRD patterns of the corresponding cocrystal (Supplementary Figs. 36 to 39). In addition, we analyzed the PXRD patterns of the samples before and after annealing. Several extra diffraction peaks were presented in the PXRD pattern of the samples before annealing, indicating the existence of some residual self-assemblies of PMDI-Δ and not well-ordered structures. After annealing, these peaks disappeared and completely co-assembled complexes with ordered stacking structures were formed (Supplementary Figs. 40 and 41).

Based on the systematic study of morphology, crystallography and spectroscopy, a possible assembly mechanism was proposed. R- (or S-) PMDI-Δ and Pyr could co-assemble into ADA sandwichs with helical chirality at the supramolecular level by size matching π-π stacking and intermolecular CT interactions. During the cooling process after annealing, the chiral defects of screw dislocations were generated, which led to the formation of homochiral 3D helicoids by continuously producing new chiral microsheets as subunits.

Discussion

In summary, we proposed a screw dislocation-driven co-self-assembly strategy to prepare homochiral 3D organic CPL-active helicoids, which was achieved by solution-processable supramolecular co-assembly through thermal annealing. By exploring the chiral expression at different length scales, a continuous chiral transfer mechanism from molecular, to supramolecular, and eventually to macroscopic levels was elucidated. Crystallographic data revealed the transfer of PMDI-Δ molecular chirality to supramolecular chirality of ADA sandwiches, which was accomplished by sandwiching Pyr between chiral PMDI-Δ molecules. Additionally, morphology observation further demonstrated that the construction of homochiral helicoids with ten micrometers-sized scales was realized in a hierarchical self-assembly driven by screw dislocations. In these processes, the chirality was strictly governed by the molecular chirality of the PMDI-Δ at different length scales. Furthermore, spectroscopic results showed that these helicoids could emit strong circularly polarized luminescence with high |glum| values. Our work not only presented an vital example of 3D organic helicoids with macroscopic chirality in supramolecular systems, but also provided a reliable and simple method for the controlled fabrication of helicoid assemblies with specific functions.

Methods

Materials

All chemicals and solvents were used without further purification. Pyromellitic dianhydride ( > 98.0%) was purchased from Energy-Chemical. Pyrene ( > 98.0%) was purchased from J&K Scientific. (1 R,2 R)-(-)−1,2-cyclohexanediamine ( > 98.0%, TCI), (1 S,2 S)-( + )−1,2-cyclohexanediamine ( > 98.0%, TCI), N,N-dimethylformamide (DMF, Concord Technology (Tianjin) Co., Ltd). AR, >99.0%), 1-Methyl-2-pyrrolidone (NMP, Inno-chem, GC, >99.5%), deionized water (Milli-Q water, 18.2 MΩ·cm) was prepared in the laboratory. The synthetic procedures of (RRRRRR)-PMDI-Δ (R-Δ) and (SSSSSS)-PMDI-Δ (S-Δ) were listed in Supplementary Fig. 1. The rac-PMDI-Δ was prepared by mixing R-PMDI-Δ and S-PMDI-Δ with equal mass.

Co-assembly protocol in DMF/H2O

Typically, R/S-PMDI-Δ (2.00 mg, 2.25 μmol, 1 eq) and pyrene (0.68 mg, 3.36 μmol, l.5 eq) were dissolved in 550 μL DMF by ultrasound to form a transparent solution. Then, 450 μL H2O (anti-solvent) was added, resulting in a yellow-green suspension (total volume 1000 μL, DMF/H2O v/v = 55%/45%, [R/S-PMDI-Δ] = 2.25 mM, [Pyrene] = 3.36 mM). The suspension was then annealed at 140 °C for 10 minutes until the charge-transfer (CT) complex between the two molecules was broken and the yellow color of the mixture completely faded. After natural cooling to room temperature, the white suspension was expected to turn yellow-green again. The precipitates were then separated by centrifugation (13000 r/min, 12000×g) and washed twice with deionized water to remove any residual organic solvent. Finally, transfer the precipitates to a clean silicon wafer, glass slide or quartz cuvette for further characterization. The detailed assembly process was shown in Supplementary Figs. 2 and 3.

To gain more insights into morphology evolution and assembly mechanism, it is essential to capture the initial structure of assemblies. Hence, it is requisite to promptly transfer the samples after annealing to a silicon wafer and remove any remaining organic solvent. For the preparation of the samples presented in Fig. 2l, which depicted a natural cooling time of 0 and 2 minutes respectively, a precipitation separation method distinct from centrifugation was employed. That is, for the samples that had just been annealed and the samples that had been left at room temperature for 2 minutes after annealing, 50 μL suspensions were pipetted and rapidly dropped onto a silicon wafer. Following that, the upper layer of liquid was removed, and the remaining precipitates on the silicon wafer were washed twice with 50 μL of deionized water. Finally, the samples were left to dry naturally at room temperature and were characterized by SEM after being coated with a thin layer of Pt in the same way as other samples.

Co-assembly protocol in NMP/H2O

Typically, R/S-PMDI-Δ (2.00 mg, 2.25 μmol, 1 eq) and pyrene (1.14 mg, 5.64 μmol, 2.5 eq) were dissolved in 600 μL NMP by ultrasound to give a transparent solution. Subsequently, 400 μL H2O (anti-solvent) was added and a yellow-green suspension was obtained (total volume 1000 μL, NMP/H2O v/v = 60%/40%, [R/S-PMDI-Δ] = 2.25 mM, [Pyrene]= 5.63 mM). The subsequent processing method of the suspension was the same as the protocol in DMF/H2O.

Self-assembly protocol

The self-assembly protocol of PMDI-Δ was the same as the co-assembly protocol above, except that the electron donor pyrene was not added.

NMR and mass spectra

1H NMR and 13C NMR spectra were recorded on a Bruker Advance spectrometer (1H: 400 MHz, 13C: 100 MHz) in CDCl3 at 298 K. Mass spectra were obtained on Bruker Solarix mass spectrometer (for ESI). The NMR and mass spectra of PMDI-Δ were shown in Supplementary Figs. 42 to 47.

Scanning electron microscopy (SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM)

SEM was performed on S4800 (Hitachi, Japan) with an accelerating voltage of 10 kV and a working current of 10 µA to ex situ characterize the co-assemblies. Before SEM measurements, the samples on silicon wafers were coated with a thin layer of Pt to increase the contrast. AFM images were obtained on a Dimension FastScan (Bruker), using ScanAsyst mode under ambient conditions. Fastscan B probes were used for the scan, and samples were prepared by dropping the aqueous dispersion of the co-assemblies onto a double-sided tape. TEM images were operated on a JEOL-2100F electron microscope operating at accelerating voltages of 200 kV.

Fluorescence microscope image (FM)

The co-assemblies were observed on an IX 83 (Olympus) fluorescence microscope. The samples were prepared by dropping the aqueous dispersion of the co-assemblies onto the glass slide and naturally dried solvent.

Ultraviolet and visible absorption spectroscopy (UV-Vis)

UV-Vis spectra were measured on a UV-Vis spectrometer (UV-2600 Shimadzu). Solution samples were loaded in a quartz cuvette with 2 mm optical path for pyrene and 1 cm optical path for PMDI-Δ. Solid samples were uniformly dispersed into BaSO4 powders to record the UV-Vis diffuse-reflectance spectra. The optical bandgaps (Eo) for helicoids were calculated from the maximum edge (λmax) of the absorption spectrum, given by the formula Eo = 1240 / λmax.

Fluorescence spectra (FL)

The fluorescence spectra were recorded on a F-4600 fluorescence spectrophotometer (Hitachi) at a voltage of 400 V with a 5 nm slit for both the excitation and emission sides. Solution samples were loaded in a quartz cuvette with 2 mm optical path for pyrene and 1 cm optical path for PMDI-Δ. The aqueous dispersion of the solid samples was charged in 1 mm quartz cuvette for FL spectra measurement. Fluorescence decay curves were recorded on a FLS 980 (Edinburgh Instruments). The wavelength of the excitation laser was 358.4 nm. Fluorescence quantum yields were measured on a FluoroMax+ (HORIBA) instrument by using an integrating sphere.

Circular dichroism (CD) and linear dichroism (LD) spectrum

Solution samples were loaded in a quartz cuvette with 2 mm optical path for pyrene and 1 cm optical path for PMDI-Δ. They were recorded on CD spectrometer J-815 (JASCO) at a scanning rate of 500 nm min−1 in the range of 200 ~ 600 nm. The CD and LD spectra of solid samples were simultaneously recorded for each sample on CD spectrometer J-1500 (JASCO) under a diffuse-reflectance mode at a scanning rate of 500 nm min−1 in the range of 200 ~ 800 nm. CD and LD spectra of each solid sample were recorded more than 3 times to ensure the chiroptical signals. The absorptive dissymmetry factor (gabs, also known as gCD) spectra were directly transferred from CD spectra using the SpectraManager software of JASCO. The gabs can be used to quantify the magnitude of CD, given by the formula gabs = 2 (εL–εR)/(εL + εR), where εL and εR refer to the extinction coefficients for left- and right-handed circularly polarized light, respectively.

Circularly polarized luminescence spectrum (CPL)

The CPL spectra were recorded on CPL-300 spectrophotometer (JASCO) in a range of 400 ~ 750 nm. The aqueous dispersion of the solid samples was charged in 1 mm quartz cuvette for CPL spectra measurement. The slits for both the excitation and emission sides were 3000 μm. The luminescence dissymmetry factor (glum) spectra were transferred from CPL spectra using the SpectraManager software of JASCO. The glum was used to quantify the extent of chiral fluorescence dissymmetry, given by the formula glum = 2 (IL–IR)/(IL + IR), where IL and IR represent the intensities of left and right circularly polarized light, respectively. CPL spectra of each solid sample were recorded more than 3 times by flipping and rotating the cuvette to ensure the chiroptical signals.

Powder X-ray diffraction (XRD) measurements

The solid samples were loaded directly onto a glass sample holder to record the X-ray diffraction spectra on EmpyreanX (PANalytical B.V.) with Cu/Kα radiation (λ = 1.5406 Å) at 40 kV and 40 mA. The scanning range was from 1° to 40°.

Single crystal X-ray diffraction (XRD) measurements

The single-crystal XRD was measured by XtaLAB Synergy-R (Rigaku). The structures were solved by direction methods and refined by a full matrix least squares technique based on F2 using SHELXL 97 program (Sheldrick, 1997).

R-PMDI-Δ single crystalDMF

In a 2 mL vial, 1.50 mg R-PMDI-Δ was dissolved in 400 μL DMF by heating and then 200 μL deionized water was added. Some white precipitates were formed immediately. After sealing the vial, the precipitates were fully dissolved by heating. Colorless transparent plate crystals were observed after standing at room temperature for about 2 days. Pick the right crystal for X-ray single crystal test.

R-PMDI-Δ/Pyr cocrystalDMF

In a 2 mL vial, 0.75 mg R-PMDI-Δ and 0.17 mg pyrene were dissolved in 266 μL DMF by heating. Following this, 133 μL deionized water was added, resulting in the formation of yellow precipitates. The vial was then sealed and the precipitates were fully dissolved by heating. Pale yellow flake R-Δ/Pyr cocrystalsDMF were prepared after standing at room temperature for about 2 days. Pick the right crystal for X-ray single crystal test.

R-PMDI-Δ/Pyr cocrystalNMP

1.0 mg R-PMDI-Δ and 1.82 mg pyrene were dissolved in 600 μL NMP by heating. The solution was then cooled and filtered with a 0.22 μm microporous membrane. The filtrate was transferred to a 2 mL vial which was placed in a 20 mL vial containing 3 mL of water. With slow vapor diffusion of H2O into the NMP solution of R-PMDI-Δ and pyrene, high-quality yellow flake R-Δ/Pyr cocrystalsNMP formed after three days. Pick the right crystal for X-ray single crystal test.

Density functional theory calculation

Density functional theory (DFT) computation was performed by Gaussian 09 Revision D.01 program at B3LYP 6-311 G** level. The initial structures of R-PMDI-Δ, CT-complexes and pyrene were extracted from corresponding single crystal data, respectively, and without further geometries optimization.