Hyperuniform Mesoporous Gold Films Coated with Halogen-Bonding Metal-Organic Frameworks for Selective Raman Sensing of Chlorinated Hydrocarbons.

Abstract

The selective detection of chlorinated aromatic hydrocarbons (CAHs) in environmental samples is challenging due to matrix interference effects. We report a surface-enhanced Raman spectroscopy (SERS) sensor that combines mesoporous Au films with UiO-66-I metal-organic framework (MOF) coatings to achieve the selective detection of CAHs. We show that mesoporous Au films can be considered hyperuniform two-dimensional (2D) materials where long-range correlations and local disorder assist in electromagnetic hotspot formation for SERS. Infiltrating the mesoporous Au films with UiO-66-I serves dual functions critical to sensor performance: First, its iodine-functionalized linkers selectively recruit CAHs from complex matrices through halogen bonding (HaB), concentrating target molecules at SERS hotspots while excluding common interferents. Second, the high refractive index of the MOF enhances light coupling by limiting scattered light, concentrating optical energy on the adsorbed CAHs for SERS enhancement. At optimal MOF thickness, the sensor achieves a detection limit below 1 × 10-10 M for 1,4-dichlorobenzene and 4-chlorobiphenyl, surpassing environmental standards by several orders of magnitude. The sensor demonstrates excellent selectivity for CAHs over common interferents, including protein, polycyclic aromatic hydrocarbons, and complex environmental matrices. Furthermore, the sensor maintains performance through multiple adsorption-desorption cycles, enabling reuse. This approach combines reticular chemistry with self-assembled nanostructured metals to achieve both high sensitivity and selectivity in complex environmental samples.