Meta-Analysis Of Azo-Functionalized Calixarenes: Synthesis, Properties, And Antibacterial Activity

Abstract

Azo-functionalized calixarenes are an increasingly attractive and structurally unique member of the supramolecular family whose functionality provides a large degree of versatility as explored in synthetic chemistry, materials science, and biomedical applications. This review is a meta-analysis of all published research work related to the synthesis, physicochemical properties and antibacterial activity of azo-substituted calixarene derivatives in three decades. Calixarenes are macrocyclic oligomers formed mainly by the condensation reaction of phenol and formaldehyde, which provide an outstanding three-dimensional hosting molecule type for azo (-N=N-) chromophoric groups forming hybrid molecules with better optic, electronic and biological properties. This meta-analysis reviews a range of peer-reviewed studies that have been systematically searched to summarize the findings related to synthetic methods, characterisation techniques including spectra analysis, host-guest interactions, photo switchable behaviour and in vitro antimicrobial activity. Above all, data compiled from more than thirty key studies demonstrate similar trends in modulatory activity as a result of increasing substitution on the azo group and/or cavity expansion of calixarenes leading to bactericidal augmentation efficacy. The review also highlights several notable gaps in available literature, especially with respect to the in vivo antimicrobial evaluation of novel compounds, detailed structure-activity relationships at the molecular level and their potential for smooth clinical translation. Together, the evidence strongly supports the conclusion that azo-functionalized calixarenes represent important new candidates for next-generation antibacterial agents and functional supramolecular materials. Finally, future perspectives are highlighted by areas of opportunities as green synthesis, drug delivery platforms and multi-drug-resistant organism targeting can be prompted in this relevant field of supramolecular chemistry.