13 research outputs found
Exercício físico reduz a hiperglicemia de jejum em camundongos diabéticos através da ativação da AMPK
Fatores associados a cesáreas em um hospital universitário de alta complexidade do sul do Brasil
Neonatal near miss and mortality: factors associated with life-threatening conditions in newborns at six public maternity hospitals in Southeast Brazil
Factors associated with normal and cesarean delivery in public and private maternity hospitals: a cross-sectional study
Calix[n] imidazolium as a new class of positively charged homo-calix compounds
Macrocycles based on neutral calixarenes and calixpyrroles have been extensively explored for ion binding, molecular assembly and related applications. Given that only these two types of calix compounds and their analogs are available, the introduction of new forms of widely usable calix macrocycles is an outstanding challenge. Here we report the quadruply/quintuply charged imidazole-based homo-calix compounds, calix[4/5] imidazolium. The noncovalent (C-H)(+)/pi(+) -anion interactions of the imidazolium rings with anions inside and outside the cone are the stabilizing factors for crystal packing, resulting in self-assembled arrays of cone-shaped calix-imidazolium molecules. Calix[4] imidazolium senses fluoride selectively even in aqueous solutions. Calix[5] imidazolium recognizes neutral fullerenes through pi(+) -pi interactions and makes them soluble in water, which could be useful in fullerene chemistry. Not only derivatization and ring expansion of calix[n] imidazolium, but also their utilization in ionic liquids, carbene chemistry and nanographite/graphene exfoliation could be exploited.close10