Azobenzene derivatives due to their photo- and electroactive properties are an important group of compounds finding applications in diverse fields. Due to the possibility of controlling the trans–cis isomerization, azo-bearing structures are ideal building blocks for development of e.g. nanomaterials, smart polymers, molecular containers, photoswitches, and sensors. Important role play also macrocyclic compounds well known for their interesting binding properties. In this article selected macrocyclic compounds bearing azo group(s) are comprehensively described. Here, the relationship between compounds’ structure and their properties (as e.g. ability to guest complexation, supramolecular structure formation, switching and motion) is reviewed.

/pdf/azo-group-s-in-selected-macrocyclic-compounds-3zor8v9joa.pdf

Azo group(s) in selected macrocyclic compounds

The key role of antioxidant transformation products in the stabilization mechanisms—A critical analysis

Two diaminocalix[4]arene monomers were synthesized from p-tert-butylcalix[4]arene through a 4-step reaction sequence. New copoly(amic acid)s containing calix[4]arene moieties on the polymer backbone were successfully synthesized in N-methyl-2-pyrrolidone by polycondensations of 4,4′-oxydiphthalic anhydride (ODPA) with the diaminocalix[4]arene monomers using 4,4′-oxydiphenylene diamine (ODA) as a comonomer. These copoly(amic acid)s were soluble in aprotic polar solvents, so that they can be processed in various ways. The copoly(amic acid) precursors were thermally converted to the corresponding copolyimides in films. The copolyimide films are amorphous, but insoluble in common solvents. They are thermally stable up to 366°C. The copolyimides exhibit relatively high TEC's, low Tg's, low refractive index, low dielectric constant, low optical anisotropy, low dielectric anisotropy, and low water uptake, compared to those of conventional ODPA-ODA polyimide. These property characteristics were interpreted in regard to bulky, cone-like calix[4]arene moieties and their effects on the chain conformation and morphological structure. The processability and property characteristics support that both of the copolyimides containing calix[4]arene moieties are potential candidate materials suitable for membranes, antioxidant additives, chemical sensor devices, and microelectronic devices. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2013–2026, 1999

M. Schulz

Papers

Calix[n]arenes—New light stabilizers for polyolefins