Intrinsic emission from nonconjugated polymers has attracted considerable attention owing to its fundamental importance and intensive applications in diverse fields. The emission mechanism, however, is still in debate. Herein, nonconjugated polyacrylonitrile (PAN) molecules are found to be virtually nonluminescent in dilute solutions, while being highly emissive when concentrated or aggregated as nanosuspensions, solid powders, and films, exhibiting distinct aggregation-induced emission (AIE) characteristics. Moreover, triplet emissions of delayed fluorescence and room temperature phosphorescence are detected from the solid powders. Such unique emission of nonconjugated PAN is ascribed to the formation of cyano clusters, which act as the exact chromophores. In these clusters, through space electronic interactions, namely overlap of π and lone pair (n) electrons among cyano groups extend the conjugation and meanwhile rigidify the molecular conformations, thus offering remarkable emission upon irradiation. The AIE phenomenon can also be well rationalized by the formation of cyano clusters together with conformation rigidification. And the triplet emissions shall be originated from the n-π* transition owing to the presence of lone pairs. It is believed that such clustering-triggered emission mechanism is instructive for further development of unorthodox luminogens.

No abstract

No abstract

Heat capacities are fundamental properties of fluids for heat transfer applications.Accurate data can be generally obtained by experimental methods, which are usually expensive, difficult and time-consuming. In terms of the calculations of heat capacities, many models have been proposed in literature. Equations of state represent one of the most promising methods, but their performance has not been systematically studied and extensively reviewed. In this work, calculations and performance of various equations of state for heat capacities are reviewed, and the different contributions to heat capacities are also discussed. The accuracy of the calculated heat capacities, as presented in literature, is also compared for some specific compounds, and the effects of different parametrization strategies as well as association schemes are analyzed. Finally, calculations for both associating and non-associating compounds are performed using two association models, Cubic Plus Association and Perturbed-Chain Statistical Associating Fluid Theory equations of state, for a wide range of compounds for which the heat capacity results from literature are available.