Chiral recognition by supramolecular porphyrin-hemicucurbit[8]uril-functionalized gravimetric sensors

Enantiorecognition of a chiral analyte usually requiresthe abilityto respond with high specificity to one of the two enantiomers ofa chiral compound. However, in most cases, chiral sensors have chemicalsensitivity toward both enantiomers, showing differences only in theintensity of responses. Furthermore, specific chiral receptors areobtained with high synthetic efforts and have limited structural versatility.These facts hinder the implementation of chiral sensors in many potentialapplications. Here, we utilize the presence of both enantiomers ofeach receptor to introduce a novel normalization that allows the enantio-recognitionof compounds even when single sensors are not specific for one enantiomerof a target analyte. For this purpose, a novel protocol that permitsthe fabrication of a large set of enantiomeric receptor pairs withlow synthetic efforts by combining metalloporphyrins with (R,R)- and (S,S)-cyclohexanohemicucurbit[8]uril is developed. The potentialitiesof this approach are investigated by an array of four pairs of enantiomericsensors fabricated using quartz microbalances since gravimetric sensorsare intrinsically non-selective toward the mechanism of interactionof analytes and receptors. Albeit the weak enantioselectivity of singlesensors toward limonene and 1-phenylethylamine, the normalizationallows the correct identification of these enantiomers in the vaporphase indifferent to their concentration. Remarkably, the achiralmetalloporphyrin choice influences the enantioselective properties,opening the way to easily obtain a large library of chiral receptorsthat can be implemented in actual sensor arrays. These enantioselectiveelectronic noses and tongues may have a potential striking impactin many medical, agrochemical, and environmental fields

Chiral Auxiliaries and Chirogenesis II

Chirality is an inevitable property of our Universe, having an enormous impact in different fields, ranging from nuclear physics and astronomy to living organisms and human beings [...

Supramolecular Chirality in Porphyrin Chemistry

Supramolecular chirality, being an intelligent combination of supramolecular chemistry and chiral science, plays a decisive role in the functioning of various natural assemblies and has attracted much attention from the scientific community, due to different applications in modern technologies, medicine, pharmacology, catalysis and biomimetic research. Porphyrin molecules are of particular interest to study this phenomenon owing to their unique spectral, physico-chemical and synthetic properties. This review highlights the most important types of chiral porphyrin structures by using the best-suited representative examples, which are frequently used in the area of supramolecular chirality

Helicene-Based Chiral Auxiliaries and Chirogenesis

Helicenes are unique helical chromophores possessing advanced and well-controlled spectral and chemical properties owing to their diverse functionalization and defined structures. Specific modification of these molecules by introducing aromatic rings of differing nature and different functional groups results in special chiroptical properties, making them effective chiral auxiliaries and supramolecular chirogenic hosts. This review aims to highlight these distinct structural features of helicenes; the different synthetic and supramolecular approaches responsible for their efficient chirality control; and their employment in the chirogenic systems, which are still not fully explored. It further covers the limitation, scope, and future prospects of helicene chromophores in chiral chemistry

Conformational Switching in Bis(Zinc Porphyrin) Langmuir-Schaefer Film as an Effective Tool for Selectively Sensing Aromatic Amines

A conformational switching of bis(zinc octaethylporphyrin) was observed, for the first time, in a Langmuir-Schaefer film as a consequence of appropriate host-guest interactions. The spectral changes are completely reversible and the high sensitivity (similar to 20 ppb) and specificity for aromatic amines open up interesting prospects of this functional material as a performing sensor for amines