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A new class of calix[4]arene crown ethers with one or two bipyridines appended to the polyether ring (lariat calixcrowns) have been designed and synthesized; the luminescence properties of their Eu3+ and Tb3+ complexes have been studied in acetonitrile. In this solvent, long lifetimes for the metal emitting states and high metal-luminescence intensities obtained upon ligand excitation have been observed in both Eu3+ and Tb3+ complexes. The association constants in methanol have been determined for some of the complexes studied.

In the European Union, according to Regulation (EU) n. 305/2011, cables permanently installed in residential and public buildings need additional classification for acidity. EN 60754-2 is the test method for assessing acidity, and three classes are provided: a1, a2, and a3 (less performant). The research on PVC compounds with low smoke acidity helps to produce cables in the best additional classes for acidity, giving the PVC cables the possibility to be used in medium and high fire risk locations. This paper shows the behavior of some acid scavengers at high temperatures performing EN 60754-2 in isothermal conditions at different temperatures between 400 °C and 950 °C. The test apparatus is a tube furnace where the test specimen is burnt, and the released gases are trapped in bubbling devices containing double deionized water. pH and conductivity are measured, the efficiency of the acid scavengers is assessed, and chemical analysis of the ashes is performed. That allows us to understand why some substances succeed and others fail in trapping hydrogen chloride (HCl). The most important conclusion in this paper is that the higher the temperature, the lower the performance of the acid scavenger, showing that HCl concentration in the gas phase depends strongly on the heating conditions of the test specimen.

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In the European Union, according to the second basic requirement for construction works of Regulation (EU) n. 305/2011, cables permanently installed in residential and public buildings must be classified in terms of reaction to fire, smoke production, flaming droplets, and acidity. The classification is harmonized; nevertheless, every European Union country decides what kind of classification a cable must have to be installed in a specific location, depending on its fire risk, following the assumption that the higher the fire risk of the area, the higher the fire performance of the cable. According to Regulation (EU) n. 305/2011, the acidity is indirectly assessed by performing EN 60754-2, giving an additional class based on pH and conductivity measurements. Hydrogen chloride (HCl) is one of the gases PVC cables release when they burn. In some applications out of the scope of the Regulation, acid scavengers are commonly used in special-grade PVC compounds to reduce the emission of acidic smoke. In this first part of the paper, the European rules on smoke acidity are presented, a review of the literature on HCl scavenging is performed, and an introduction on HCl scavenging at high temperatures is outlined. The paper shows how different experimental conditions and geometries of the test apparatuses used for assessing the smoke acidity can affect the emission of HCl in the gas phase and what critical issues affect the efficiency of acid scavengers at high temperatures in trapping HCl.