Pathway-directed recyclable chirality inversion of coordinated supramolecular polymers

Abstract

It remains challenging to elucidate the fundamental mechanisms behind the dynamic chirality inversion of supramolecular assemblies with pathway complexity. Herein, metal coordination driven assembly systems based on pyridyl-conjugated cholesterol (PVPCC) and metal ions (Ag⁺ or Al³⁺) are established to demonstrate pathway-directed, recyclable chirality inversion and assembly polymorphism. In the Ag(I)/PVPCC system, a competitive pathway leads Ag-Complex to form either kinetically controlled supramolecular polymer (Ag-SP I) or thermodynamically favored Ag-SP II, accompanied by reversible chiroptical inversion. Conversely, the Al(III)/PVPCC system displays a solvent-assisted consecutive pathway: the Al-Complex initially forms ethanol-containing Al-SP II, and subsequently converts into ethanol-free Al-SP I with opposite chiroptical performance upon thermal treatment. Moreover, stable chirality inversion in the solid state enables potential dynamic circularly polarized luminescence encryption when Ag(I)/PVPCC is co-assembled with thioflavin T. These findings provide the guidance for the dynamic modulation of chirality functionality in supramolecular materials for applications in information processing, data encryption, and chiral spintronics.

Fig. 1. Dynamic supramolecular chirality inversion of MOSPs regulated by competitive and consecutive pathways.

Schematic illustration of Ag(I)/PVPCC and Al(III)/PVPCC assembly systems with supramolecular polymorphs and dynamic supramolecular chirality inversion at both ground-state and excited-state regulated by (a) competitive and (b) consecutive assembly pathways. The triangle represents the heating process, and the snowflake signifies the cooling process.

Fig. 2. Dynamic supramolecular chirality inversion and morphology transformation of Ag(I)/PVPCC assemblies.

a CD spectra of Ag(I)/PVPCC assemblies subjected to ultrasound (blue line) and thermal treatment (red line) in PX/n-BuOH, respectively (v/v, 1/1, [PVPCC] = 16 mM, n_PVPCC/n_Ag⁺ = 2/1). b Positive-ion MALDI-TOF-MS of the PVPCC+AgOTf solution. c Time-dependent rheological properties of the Ag(I)/PVPCC assemblies. d Macroscopic phase transitions of Ag(I)/PVPCC mixtures and corresponding (e, f) SEM and (g) TEM measurements of (e) Ag-SP I xerogel after freeze-drying treatment, as well as (f) p-Ag-SP II and (g) Ag-SP II after drying under the vacuum oven at 323 K. h Single-crystal structure of Ag(I)/PVPCC obtained from CHCl₃/PX/EtOH (4/1/2, v/v/v). i Packing mode of Ag(I)/PVPCC complex in the single crystal along the a axis.

Fig. 3. Chirality inversion of Ag-Complex assemblies regulated by the competitive pathways.

a, b CD evolution of the heated Ag-Complex solution after cooling at room temperature for (a) 0–2 min and (b) 2–20 min. c CD intensity of Ag(I)/PVPCC assemblies recorded during alternating cycles of heating at 363 K for 2 min, cooling at 297 K for 1 min, and further cooling at 297 K for additional 2 min. d Normalized CD intensity (φ_n) of the corresponding Ag(I)/PVPCC mixtures at 380 nm (heating process, red dots) and 360 nm (cooling process, blue dots) as a function of the temperature. e Temperature-dependent CD spectra of Ag(I)/PVPCC mixtures cooling from 363 to 297 K with a programable cooling rate at 1 K min⁻¹. f, g Time-dependent CD intensity of Ag(I)/PVPCC assemblies at 360 nm monitored at different (f) temperature and (g) concentrations. h Energy landscape representing the proposed competitive assembly pathways of Ag-Complex with dynamic chirality inversion.

Fig. 4. Solvent-mediated Al-Complex assembly with consecutive pathway-modulated chirality inversion.

a Time-dependent g_abs values at 393 nm of Al(III)/PVPCC assemblies in a cuvette at room temperature (RT) ([PVPCC] = 16 mM, n_PVPCC/n_Al³⁺ = 2/1, PX/EtOH, v/v, 99/1). b CD spectra of Al(III)/PVPCC assemblies after heating for 3 min at 373 K, resting for 1 min and 7 days at room temperature, and adding ethanol again, respectively. c Morphologic evolution of Al(III)/PVPCC assemblies monitored by SEM (inset is TEM) at 298 K. d Time-dependent normalized CD intensity of transformation from Al-SP I to Al-SP II with different concentrations at 298 K. e Time-dependent CD spectra and of Al(III)/PVPCC assemblies in a cuvette at 373 K. f Schematic illustration of the assembly mechanism of Al(III)/PVPCC in PX/EtOH (v/v, 99/1). The triangle represents the heating process, and the snowflake signifies the cooling process.

Fig. 5. Inverted CPL of Ag(I)/PVPCC and Al(III)/PVPCC assemblies.

a–c CPL spectra of (a) Ag-SP I and p-Ag-SP II, (b) Ag-Complex, and (c) Ag-SP I and Ag-SP II in PX/n-BuOH (v/v, 1/1, [PVPCC] = 16 mM, n_PVPCC/n_Ag⁺ = 2/1). d Schematic illustration of the CPL transformation process of Ag(I)/PVPCC assemblies. The clock motif symbolizes the passage of time, the triangle represents the heating process, and the snowflake signifies the cooling process. e Time-dependent CPL spectra of Al(III)/PVPCC assemblies in PX/EtOH (v/v, 99/1, [PVPCC] = 16 mM, n_PVPCC/n_Al³⁺ = 2/1). f, g CPL spectra of (f) Ag(I)/PVPCC xerogels and (g) Al(III)/PVPCC assemblies.

Fig. 6. Dynamic information encryption in co-assembled system of ThT and Ag(I)/PVPCC.

a, b Normalized absorption (dashed line) and emission (solid line) spectra of (a) Ag-SP I (blue lines) and ThT (red lines), and (b) Ag-SP II (orange lines) in PX/n-BuOH. The shaded areas indicate the overlap between the ThT absorption spectrum and the emission spectrum of Ag-SP I (or Ag-SP II). c CPL spectra of ThT⊂Ag-SP I (blue line) and ThT⊂Ag-SP II (red line) in PX/n-BuOH (v/v 1/1, [PVPCC] = 16 mM, n_PVPCC/n_Ag⁺  =  2/1, n_PVPCC/n_ThT = 10/1). d Pattern designed with different phosphors. e Variety of PL and CPL in ThT⊂Ag(I)/PVPCC, Ag(I)/PVPCC, ThT, and PVPCC at the different excitation wavelengths. f An experimental model for the multilevel information encryption device. The different information at 420 nm (PL and CPL) and 510 nm (PL and CPL) could be displayed by modulating the excitation wavelength (λ_ex = 300 or 410 nm) and output mode.