Calixarenos como plataforma de luminóforos e de co-cristalização com nutracêuticos

Abstract

Calixarenes are notable macrocyclic compounds characterized by a variable number of phenolic units linked by methylene bridges. They possess a series of advantageous features, making them an ideal choice for diverse applications. Their ease of large-scale production from low-cost precursors, coupled with their chemical and thermal stability, as well as the ease of functionalization, elevate calixarenes to the status of highly versatile platforms. They can be utilized in the development of a broad range of materials with potential applications in technological and pharmacological areas. Based on the host-guest properties of calixarenes and the high efficiency of aminopyrazine as a blue light emitter, this research focused on the investigation of two calixarene-pyrazinamide hybrids. The primary goal was to combine hosting capabilities and light emission in a single molecular structure. Two compounds yielded three luminescent crystalline forms, whose structures and optical properties could be correlated. One of them crystallized in two forms, non-solvated and a DMF solvate, while the other, without t-butyl substitutions, formed three conformers with DMF. Variations in molecular substitution affected the conformation of the structures, influencing the coplanarity and conformational profile of the phenolic rings. Under an excitation of 388 nm, both emitted light in the 400-550 nm range, peaking at around 500 nm, but with low quantum efficiency. The low efficiency was attributed to the presence of DMF and π...π stacking interactions. Another aim of this research was to explore the use of calix[4]tube in forming cocrystals with resveratrol, an active nutraceutical known for its potential antibacterial, antioxidant, antiinflammatory, and anticarcinogenic benefits, yet with low aqueous solubility. This work represents the first successful attempt to form a neutral-state resveratrol cocrystal, doubling its water solubility. In summary, this study signifies a significant advancement in using calixarenes as molecular bases for luminophores and in the crystallization of the nutraceutical resveratrol. The employed process proved commercially viable, underlining the immense potential of these methods for future applications in technological and pharmaceutical fields. Therefore, the research focuses on the synthesis of calixarene hybrids with light-emitting properties and the development of cocrystals to enhance the solubility of pharmaceutical compounds, demonstrating the versatility of calixarenes in various areas of chemistry.