The development of functional supramolecular polymers relies heavily on the strategic integration of orthogonal non-covalent interactions to achieve precise control over self-assembly pathways. In this study, we present a linear supramolecular polymer constructed via the synergistic combination of quadruple hydrogen bonding and anion recognition, both operating in parallel yet independently within a single molecular framework. The system is based on a calix[4]pyrrole (CP) scaffold functionalized with a ureidopyrimidinone (UPy) unit, enabling dual recognition capabilities. The UPyCP derivative was synthesized by reacting a hydroxypropyl-calix[4]pyrrole with an isocyanate-modified pyrimidinone, yielding a molecule capable of forming stable dimers via self-complementary quadruple hydrogen bonds, as confirmed by ¹H-NMR and ESI-MS.
To evaluate the potential for hierarchical assembly, the interaction between UPyCP and tetrabutylammonium suberate (TBAS) was systematically investigated using ¹H-NMR titration in CDCl₃. While the UPy NH signals remained unaltered throughout the titration, indicating that the dimeric integrity of UPyCP was preserved, significant changes were observed in the pyrrole NH region. Initially appearing at 7.04 ppm, these signals shifted to 7.17 ppm upon addition of 0.22 equiv TBAS, followed by the emergence of a broad peak at 7.77 ppm—characteristic of anion binding to the CP cavity. As the TBAS concentration increased, the peak at 7.77 ppm moved upfield to 8.15 ppm, while a new signal emerged at 9.63 ppm at 0.66 equiv, suggesting the formation of higher-order complexes where two TBAS molecules bind to one UPyCP dimer.
Variable concentration ¹H-NMR analysis revealed progressive line broadening as the concentration of the equimolar UPyCP/TBAS mixture increased from 10 to 333 mM. This phenomenon reflects the growth of large, dynamic aggregates resulting from intermolecular interactions. Notably, three distinct pyrrole NH peaks at low concentration merged into a single broad resonance at 9.08 ppm at 333 mM, strongly indicating the formation of high-degree supramolecular polymers. The upfield shift of pyrrole CH protons from 5.84 to 5.62 ppm further supports strong complexation between CP and carboxylate groups at high concentrations.
Solution viscosity measurements demonstrated a clear transition above 28 mM, with a nonlinear increase in specific viscosity (Vs).80451-05-4 Synonym A slope of 2.p53 Antibody manufacturer 22 in the double-logarithmic plot confirms the presence of high molecular weight species.PMID:34916656 DOSY NMR analysis showed a substantial decrease in diffusion coefficient (D) from 5.73 × 10⁻¹⁰ m² s⁻¹ at 5 mM to 1.27 × 10⁻¹⁰ m² s⁻¹ at 110.5 mM, consistent with the formation of extended chains. Scanning electron microscopy (SEM) imaging of a fiber drawn from a highly concentrated solution revealed a continuous, rod-like structure with a diameter of 38.5 μm, providing direct morphological evidence of supramolecular polymerization.
Thermal responsiveness was confirmed through variable temperature viscosity experiments: increasing temperature from 25 °C to 50 °C caused a sharp drop in Vs from 4.42 to 1.82, reflecting reversible disassembly. Furthermore, addition of TBAF as a competing anion disrupted both the UPy dimer and CP-anion interactions, leading to a nonlinear decrease in viscosity and dramatic shifts in NMR signals. These results confirm the dynamic and stimuli-responsive nature of the system. This work establishes a new paradigm for constructing linear supramolecular polymers using orthogonal interactions between UPy-based hydrogen bonding and anion-recognition-driven host-guest chemistry, offering promising avenues for smart materials and adaptive systems.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com
