Prismarene-based chemoSensors for monitoring organic water contaminants
P2022XHLTX, CUP D53D23017250001
Organic water-contaminants (OWCs), such as PAHs, PFAS, HCB and hydrophilic OWCs, can cause adverse ecological and human health effects. Consequently, action is urgently needed for prevention of these pollutants, thus limiting OWCs possible risk to health and environment and guaranteeing healthy freshwater and seas. These actions require constant and real time environmental monitoring for the fast and selective pollutants detection, thus leading to an increasing demand of portable and even wearable sensing devices. In fact, OWCs are typically present in very low concentrations and in complex mixtures, then requiring a sensitive and selective detection. Chromatographic methods combined with mass spectrometry are frequently employed for the qualitative and quantitative detection of OWCs, allowing to achieve high sensitivity and selectivity. However, they are limited by the necessity for large and expensive analysis equipment, which cannot be employed “on site”, and of specialized workers, being thus inappropriate for remote monitoring of environment and water pollution. As a result, there is still a need for trustworthy, adaptable, and cost-effective techniques. Among the OWCs, pesticides and drugs are often chiral and can be found in water in optically active form. In fact, even if they are usually marketed as racemic mixtures, recent studies have shown that degradation of chiral organic water contaminants is often enantioselective, giving rise to scalemic, enantiomerically enriched mixtures. Moreover, enantiomers of chiral compounds often have different distribution fate, bioaccumulation potential, and toxicity. It follows that fast determination of the absolute configuration and enantiomeric excess (ee) of chiral pollutants in the environment is important for accurate environmental and human health risk assessment. Thus, optical chirality sensing employing host-guest chemistry coupled with detection through chiroptical spectroscopies would be affordable and suitable for high-throughput screening approach.
Aim of the PrismaSens project will be the development of novel supramolecular chemosensors based on host-guest recognition processes for the monitoring of OWCs in complex matrices.
In this project, we will focus our attention on a limited number of OWC targets, which give rise to particular concern not only in the densely populated southern regions, like Campania region, in industrial areas such that of Porto Torres in Sardinia and in other parts of Italy and the rest of the world. The targets have been chosen among those emerging water contaminants that still miss established and fast analytical detection methods.
In addition, PrismaSens project will focus attention on the use of a novel class of chiral macrocycles named prism[n]arenes, as fluorescent receptors for the design of novel chemosensors for the detection and the monitoring of OWCs.
The Scientific Contribution of SupraChem@Unisa Group
Pubblications
The carboxylato-prism[6]arene acts as an efficient catalyst for the oxidation of aromatic amines in water, utilizing hydrogen peroxide (H2O2) as a green oxidant. The findings indicate that forming supramolecular endo-cavity complexes between aniline derivatives and the prism[6]arene is essential for catalytic activity. Calorimetric investigations demonstrate that this complex formation is primarily driven by entropic factors associated with expulsing frustrated water molecules from the deep hydrophobic cavity of the prism[6]arene. In silico studies further confirm the presence of these water molecules within the cavity and their subsequent release upon the introduction of aromatic amines. Additionally, a computational approach was employed to elucidate the initial oxidation steps of aniline within the prism[6]arene cavity. This encapsulation process significantly lowers the activation free energy by 34.94 kJ mol−1, thereby enhancing reactivity through hydrogen bonding and solvent effects. The computational results closely align with experimental data, underscoring the critical role of host–guest interactions within the deep cavity of the prism[6]arene in facilitating the oxidation process.
Chem. Sci., 2025,16, 18223-18232
This study presents the first report of an inherently chiral prismarene with resolved enantiomers. Prism[4]arenes, synthesized via a thermodynamic template approach using a tailor-made selective cation, effectively maintain their chirality due to their strained macrorings and narrow annuli, which prevent the flipping of naphthalene rings. The solid-state structure of the synthesized PrS[4]iPe revealed a racemic crystal composed of all-pR and all-pS enantiomeric pairs, forming supramolecular polymeric chains of homochiral molecules interlinked by intermolecular host–guest interactions. Both enantiomers were resolved by using chiral high-performance liquid chromatography (HPLC), and their chiroptical properties were thoroughly investigated. Configurational assignment was achieved through time-dependent density functional theory (TDDFT) computations alongside electronic circular dichroism/ultraviolet–visible (ECD/UV–vis) spectral analysis. Notably, the circularly polarized luminescence (CPL) properties exhibited a significant dissymmetry ratio of 0.008 for these prism[4]arenes, due to electric and magnetic dipole transition moments both directed along the cylinder axis. Furthermore, the ability of PrS[4]iPe to achieve enantioselective recognition with chiral ammonium guests was demonstrated.
J. Am. Chem. Soc. 2025, 147(24), 20843-20854
A water-soluble prism[5]arene host can form endo-cavity complexes with hydrophilic organic substances in water by displacing frustrated water molecules from its deep cavity. Water molecules structured at both rims of the prismarene host can mediate hydrogen bonding interactions with the guest. Water-mediated hydrogen bonding interactions were invoked here to elucidate the elevated binding affinities and selectivity of the prismarene host toward hydrophilic organic guests. We show that water at the interface of a host-guest complex can act as an extension of the host structure, facilitating the accommodation of neutral guests within the binding site. This study highlights the crucial role of water in facilitating supramolecular interactions between a deep-cavity prismarene host and organic hydrophilic guests in aqueous medium.
Chem. Eur. J. 2024, 30(44), e202401734
Chirality Sensing of Cryptochiral Guests with Prism[n]arenes
Optical chirality sensing has gained significant attention in recent years. Within this field, the quest for stereodynamic chiroptical probes capable of detecting cryptochiral guests presents a formidable challenge. Macrocycles exhibiting planar chirality have emerged as promising candidates for amplifying the chirality of cryptochiral guests. In this study, we demonstrate that the formation of host-guest complexes between cryptochiral molecules and planar chiral prismarenes triggers electronic circular dichroism (ECD) signals via host-guest complexation-induced chirality amplification. The absolute configuration of the most stable chiral macrocyclic host-guest complex has been established by resorting to both exciton model and DFT computations. Furthermore, we demonstrated that this supramolecular chirality sensing system can be employed to determine the enantiomeric composition of scalemic mixtures by measuring the ECD bands intensity. The information described here opens the way for the use of prismarenes as stereodynamic probes for sensing of cryptochiral guests.
Chem. Eur. J. 2024, 30(40), e202401625
