The synthesis of calix[2]thia[4]phyrin 3, a core-modified expanded calixphyrin, by an efficient synthetic route is reported. 3 exhibits an aggregation-induced enhanced emission (AIEE) phenomenon upon addition of increasing amounts of water. This is attributed to the restricted intramolecular rotation of the meso-aryl rings present on the sp(3) bridging carbons. SEM studies revealed the formation of aggregation in an acetonitrile/water mixture with an average diameter of the aggregate in the range 0.38-2.08 μm. The photoluminescence quantum yield of 3 in 9:1 water/acetonitrile is 5-fold higher than the quantum yield in acetonitrile alone. Single-crystal X-ray analysis of 3 revealed a chairlike conformation stabilized by N-H···N and C-H···π intramolecular hydrogen-bonding interactions. Fluorine atoms on the meso-pentafluorophenyl groups are involved in C-H···F intermolecular hydrogen-bonding interactions to generate a two-dimensional supramolecular assembly in the solid state. In the diprotonated state, 3 has affinity for anions and forms 1:1 complexes with SO4(2-), NO3(-), Cl(-), and ClO4(-) in solution. The tetrahedral anions bind more strongly than the other anions. Single-crystal X-ray structure studies of the ClO4(-) anion complex with 3 revealed the formation of both 1:1 and 1:2 complexes in the solid state, with the host and the guest being held together by N-H···O hydrogen-bonding interactions.

Painters experience occupational exposure through inhalation and skin absorption to various chemicals that are used as ingredients of paint mixtures and other related painting trades. Although several investigations indicated significant contribution of exposure via skin absorption to exhibit harmful effects on health among painters, assessment of the skin absorption hazards of the paint chemicals is limited. Here, we evaluated the skin absorption of a number of organic chemicals relevant to painting trades using mathematical models. For this purpose, we estimated the skin permeability coefficient of the chemicals using the Potts and Guy correlation equation. The estimated permeability coefficients were further utilized to estimate the maximum flux of the non-volatile chemicals across the skin. The skin permeability coefficient and maximum flux of the chemicals across the skin were compared to those of the chemicals to which the American Conference of Governmental Industrial Hygienists (ACGIH) assigned a “skin” notation. We critically analyzed the estimated maximum fluxes and the acute toxicity data of the chemicals available in the literature that helped to identify the chemicals posing a significant skin absorption hazard. The analyses suggest that triethanolamine and m-phenylenediamine pose significant skin absorption hazards, though these chemicals have not yet been assigned a “skin” notation in the ACGIH TLV book. The ratio of dermal uptake directly from air to inhalation intake of volatile solvents used in paint mixtures was estimated for a typical occupational setting. N-Methyl-2-pyrrolidone showed significant dermal uptake fraction compared to its intake via inhalation route.