The contribution of metalloporphyrin complexes in molecular sensing and in sustainable polymerization processes: a new and unique perspective

Multifaceted Applications of Luminescent Metalloporphyrin Derivatives: Fluorescence Turn-On Sensing of Nicotine and Antimicrobial Activity

In this study, we designed and synthesized metalloporphyrin derivatives (with Ni and Zn) specifically intended for the fluorescence detection of nicotine in aqueous solutions. Our results showcased a notable selectivity for nicotine over other naturally occurring food toxins, exhibiting an exceptional sensitivity with a limit of detection as low as 7.2 nM. Through mechanistic investigations (1H NMR, FT-IR, etc.), we elucidated the binding mechanism, revealing the specific interaction between the pyridine ring of nicotine and the metal center, while the N atom pyrrolidine unit engaged in the hydrogen bonding with the side chain of the porphyrin ring. Notably, we observed that the nature of the metal center dictated the extent of interaction with nicotine; particularly, Zn-porphyrin demonstrated a superior response compared to Ni-porphyrin. Furthermore, we performed the quantitative estimation of nicotine in commercially available tobacco products. Additionally, we conducted the antibacterial (Staphylococcus aureus and Escherichia coli) and antifungal (Candida albicans) activities of the porphyrin derivatives.

A guide to modern methods for poly(thio)ether synthesis using Earth-abundant metals

Polyethers and polythioethers have a long and storied history dating back to the start of polymer science as a distinct field. As such, these materials have been utilized in a wide range of commercial applications and fundamental studies. The breadth of their material properties and the contexts in which they are applied is ultimately owed to their diverse monomer pre-cursors, epoxides and thiiranes, respectively. The facile polymerization of these monomers, both historically and contemporaneously, across academia and industry, has occurred through the use of Earth-abundant metals as catalysts and/or initiators. Despite this, polymerization methods for these monomers are underutilized compared to other monomer classes like cyclic olefins, vinyls, and (meth)acrylates. We feel a focused review that clearly outlines the benefits and shortcomings of extant synthetic methods for poly(thio)ethers along with their proposed mechanisms and quirks will help facilitate the utilization of these methods and by extension the unique polymer materials they create. Therefore, this Feature Article briefly describes the applications of poly(thio)ethers before discussing the feature-set of each poly(thio)ether synthetic method and qualitatively scoring them on relevant metrics (e.g., ease-of-use, molecular weight control, etc.) to help would-be poly(thio)ether-makers find an appropriate synthetic approach. The article is concluded with a look ahead at the future of poly(thio)ether synthesis with Earth-abundant metals.

V-Porphyrins Encapsulated or Supported on Siliceous Materials: Synthesis, Characterization, and Photoelectrochemical Properties

Metalloporphyrin-containing mesoporous materials, named VTPP@SBA, were prepared via a simple anchoring of vanadyl porphyrin (5,10,15,20-Tetraphenyl-21H,23H-porphine vanadium(IV) oxide) through a SBA-15-type mesoporous material. For comparison, vanadyl porphyrin was also impregnated on SiO₂ (VTPP/SiO₂). The characterization results of catalysts by XRD, FTIR, DR-UV-vis, and EPR confirm the incorporation of vanadyl porphyrin within the mesoporous SBA-15. These catalysts have also been studied using electrochemical and photoelectrochemical methods. Impedance measurements confirmed that supporting the porphyrin in silica improved the electrical conductivity of samples. In fact, when using mesoporous silica, current densities associated with oxidation/reduction processes appreciably increased, implying an enhancement in charge transfer processes and, therefore, in electrochemical performance. All samples presented n-type semiconductivity and provided an interesting photoelectrocatalytic response upon illumination, especially silica-supported porphyrins. This is the first time that V-porphyrin-derived materials have been tested for photoelectrochemical applications, showing good potential for this use.

Self-Assembly of Chiral Cyclohexanohemicucurbit[n]urils with Bis(Zn Porphyrin): Size, Shape, and Time-Dependent Binding

In order to investigate the ability of bis(zinc octaethylporphyrin) (bis–ZnOEP) to discriminate cyclohexanohemicucurbit[n]urils (cycHC[n]) of different shapes and sizes, the self-assembly of barrel-shaped chiral cycHC[n] with bis–ZnOEP was studied by various spectroscopic methods (absorption, fluorescence, circular dichroism (CD), and NMR). While the binding of 6-membered cycHC[6] induced a tweezer-like conformation followed by the formation of anti-form of bis–ZnOEP upon further addition of cycHC[6], the interaction of 8-membered cycHC[8] is more complex and proceeds through the featured syn-to-anti conformational change of bis–ZnOEP and further intermolecular self-assembly via multiple noncovalent associations between cycHC[8] and bis–ZnOEP. Whilst bis–porphyrins are known to be effective chemical sensors able to differentiate various guests based on their chirality via induced CD, their ability to sense small differences in the shape and size of relatively large macrocycles, such as chiral cycHC[6] and cycHC[8], is scarcely examined. Both studied complexes exhibited characteristic induced CD signals in the region of porphyrin absorption upon complexation.