Studies on Novel Photoluminescent Pyridinophanes & Macrocycles Comprising of Mg/N & P/N Units and Photoresponsive Phosphazane-Azo Macrocycles

Abstract

Macrocyclic molecules have attracted a lot of interest in areas including coordination chemistry, molecular recognition, and catalysis because of their intriguing ring configurations and striking structural versatility. The creation of synthetic macrocyclic complexes that mimic naturally occurring systems like porphyrins, metalloproteins, cobalamin, and vancomycin has been motivated by nature, a crucial source of bioactive macrocycles. Although organic macrocycles have significantly influenced several branches of chemistry, synthetic difficulties have hampered research into inorganic and organic-inorganic hybrid macrocycles. Since the last decades, phosph(III)azane dimers of the type, [ClP(µ-NR)]2 have proven to be excellent building blocks for the formation of a variety of inorganic macrocycles. While the cis–trans equilibrium is significantly influenced by solvents and their electronic effects, temperature, and often large activation barriers hinder this equilibrium, resulting in the formation of kinetic products. In the present study, we investigated the utilization of cyclodiphosh(III)azanes, [ClP(µ NtBu)]2, as an inorganic building block, for the synthesis of inorganic-organic hybrid macrocycle and cryptands, their reactivity with metals salts and borane. The second section of the work describes our efforts towards photoresponsive (E-Z photoisomerization) phosphazane-azo macrocycles. The last section of the work shows how the preorganized building block bis(trimethylsilyl)–N,N’-2,6-diaminopyridine (bap) can be used to create a variety of interesting cyclic structures, such as pyridinophanes, cluster complexes, and bicyclic pyridinophanes with -N-Mg-N- and -N-Sb-N- inorganic bridges and study their luminescence properties thoroughly. Overall, our methodologies represent novel approaches for the synthesis of hybrid organic-inorganic macrocycles containing important main group elements. The knowledge gathered from this investigation advances our comprehension of the connection between luminescent characteristics and the possibility of having photo-responsive motifs in macrocyclic systems.