Exploration of Alkyne-Based Multilayered 3D Polymers and Oligomers: Subtle Aggregation-Induced Emission, Chromium(VI) Ion Detection, and Chiral Properties Characterization

Abstract

This study investigates the synthesis and characterization of alkyne-based multilayered three-dimensional (3D) polymers, which exhibit a subtle aggregation-induced emission (AIE) phenomenon. The polymers demonstrate significant potential as fluorescent probes for the selective detection of chromium (VI) ions (Cr⁶⁺), showcasing their utility in environmental sensing applications. Additionally, the circular dichroism (CD) spectra reveal a pronounced cotton effect, indicative of chiral properties, while scanning electron microscopy (SEM) and dynamic light scatting (DLS) analysis reveal a distinctive rock-like surface morphology and Cr⁶⁺ sensitive anti-aggregation. These findings highlight the multifunctional capabilities of alkyne-based multilayered 3D polymers, suggesting their applicability in both fluorescence-based sensing and materials science. The insights gained from this research contribute to the development of advanced materials with tailored optical properties for environmental monitoring and other practical applications.

Keywords: aggregation-induced emission; chiral properties characterization; chromium (VI) ion detection; multilayered 3D polymer.

Figure 1

(a,b) Former synthesized multilayered 3D polymer. (c) This work.

Figure 2

Synthetic method of monomer 1-1 and 1A.

Figure 3

Synthetic method of polymer 2A and 3A.

Figure 4

UV-vis absorption spectrum of 1A, 2A, and 3A. Concentration: 0.05 mg/mL in THF.

Figure 5

(a–c) PL spectra of 1A, 2A, and 3A in THF/water mixtures with different methanol fractions (f_w); c = 0.05 mg/mL; inset: fluorescence photographs of 1A, 2A and 3A in THF/methanol system; Excitation wavelength: 317 nm. (d) Stern–Volmer plots of I₀/I vs. methanol fraction of 1A, 2A, and 3A.

Figure 6

(a,b) Fluorescence emission profile of polymers 2A and 3A (0.05 mg/mL) in the presence of various metals ion solvents of Ba²⁺, Ca²⁺, Cr⁶⁺, Cu²⁺, Fe³⁺, K⁺, Mg²⁺, Mn²⁺, Mo²⁺, Na⁺, Ni²⁺, Pb²⁺, and Zn²⁺ 5 µL in PBS buffer (20 mM pH 7.4) solution (THF). Excitation wavelength: 331 nm. (c,d) Fluorescence response of 0.05 mg/mL polymer 2A and 3A to various metal ions. Excitation at 331 nm.

Figure 7

(a,b). Concentration-dependent fluorescence spectra of 2A and 3A (0.05 mg/mL) on the addition of various amounts of Cr⁶⁺ (0–350 µM) in PBS buffer (20 mM pH 7.4) solution (THF). The excitation wavelength was 331 nm. (c,d) Stern–Volmer plots of I/I₀ vs. Cr⁶⁺ concentration for 2A and 3A.

Figure 8

CD Spectroscopy of polymer 3A in THF. (c = 0.2 mg/mL).

Figure 9

SEM images of polymers 2A and 3A (a,b).

Figure 10

(a–c) DLS particle size distribution curves of 1A, 2A, and 3A in THF. (d,e) DLS particle size distribution curves of 2A and 3A with Cr⁶⁺ ion.