The entire world has been suffering from the coronavirus disease 2019 (COVID‐19) pandemic since March 11, 2020. More than a year later, the COVID‐19 vaccination brought hope to control this viral pandemic. Here, we review the unknowns of the COVID‐19 vaccination, such as its longevity, asymptomatic spread, long‐term side effects, and its efficacy on immunocompromised patients. In addition, we discuss challenges associated with the COVID‐19 vaccination, such as the global access and distribution of vaccine doses, adherence to hygiene guidelines after vaccination, the emergence of novel severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) variants, and vaccine resistance. Despite all these challenges and the fact that the end of the COVID‐19 pandemic is still unclear, vaccines have brought great hope for the world, with several reports indicating a significant decline in the risk of COVID19‐related infection and hospitalizations.

No abstract

No abstract

Bis-imidazolium cations, 1,1 0 -[1,4-phenylenebis(methylene)]bis(3-R-1H-imidazolium-1-yl), (R = methyl or n-butyl), form discrete multicomponent complexes in water with various phosphonium cations, anionic p-sulfonatocalix[4]arene, and aquated gadolinium(III) ions. The terminal alkyl groups, R, reside in the cavities of the calixarenes, with two calixarenes either adjacent to each other, where they face the same direction and are in the same bilayer arrangement made of calixarenes and phosphonium cations, or where they face opposite directions. Here the calixarenes are similarly part of a bilayer arrangement, or they are part of an extended structure which can be regarded as being built from the assembly of supermolecules or "molecular capsules", [(bis-imidazolium)⊂(p-sulfonatocalix[4]arene) 2 ], which are π-stacked through the calixarenes in a head-to-tail fashion. The nature of the product depends on the length of the terminal alkyl group, and the choice of phosphonium cation.

No abstract