A Record Chromophore Density in High-Entropy Liquids of Two Low-Melting Perylenes: A New Strategy for Liquid Chromophores

作者：Kushwaha Khushbu; Yu Liyang; Stranius Kati; Singh Sandeep Kumar; Hultmark Sandra; Iqbal Muhammad Naeem; Eriksson Lars; Johnston Eric; Erhart Paul; Mueller Christian; Borjesson Karl^*

来源：Advanced Science, 2019, 6(4): 1801650.

DOI：10.1002/advs.201801650

• alkylation
• high quantum yield
• liquid fluorophores
• low melting solids
• thermodynamic mixing

Liquid chromophores constitute a rare but intriguing class of molecules that are in high demand for the design of luminescent inks, liquid semiconductors, and solar energy storage materials. The most common way to achieve liquid chromophores involves the introduction of long alkyl chains, which, however, significantly reduces the chromophore density. Here, strategy is presented that allows for the preparation of liquid chromophores with a minimal increase in molecular weight, using the important class of perylenes as an example. Two synergistic effects are harnessed: (1) the judicious positioning of short alkyl substituents, and (2) equimolar mixing, which in unison results in a liquid material. A series of 1-alkyl perylene derivatives is synthesized and it is found that short ethyl or butyl chains reduce the melting temperature from 278 degrees C to as little as 70 degrees C. Then, two low-melting derivatives are mixed, which results in materials that do not crystallize due to the increased configurational entropy of the system. As a result, liquid chromophores with the lowest reported molecular weight increase compared to the neat chromophore are obtained. The mixing strategy is readily applicable to other pi-conjugated systems and, hence, promises to yield a wide range of low molecular weight liquid chromophores.

• 出版日期2019-2-20