Supercooling of functional alkyl-π molecular liquids

Abstract

The formation of a metastable supercooled alkyl-π molecular liquid was prohibited by subtle alteration of the molecular structure.

Synthesis of Oligo(1,8‐pyrenylene)s: A Series of Functional Molecular Liquids

“…Small‐ and wide‐angle X‐ray scattering (SWAXS) measurements of trimer 11 a showed no features at all in the small‐angle range and just very broad peaks at 21.0° and 42.5° in the wide‐angle region (Figure ). The former corresponds to a distance of 4.23 Å, which is typical of an alkyl halo, and the peak at 42.5° is likely the corresponding second order peak (corresponds to a distance of 4.25 Å). The absence of any sharp peaks is indicative of the absence of long‐range molecular ordering, which speaks to 11 a being a liquid.…”

Solvent‐Free Luminous Molecular Liquids

“…Moreover, such LMLs often exhibit low viscosities. For instance, the LMLs of alkylated tetrazines and alkylated naphthalenes exhibit complex viscosities (η*) in the ranges of 28–58 and 38–67 mPa • s, respectively, which are much lower than the η* of alkylated oligo( p ‐phenylenevinylene)s (0.64–34.6 Pa • s), alkylated 9,10‐diphenylanthracenes (0.28–84.0 Pa • s), alkylated pyrenes (2.3–58.0 Pa • s), and an alkylated bromonaphthalimide (0.79 Pa • s) . Such low viscous LMLs are promising for developing refreshable devices owing to their facile refilling.…”

“…If the chains are too short, the T m cannot be reduced effectively due to insufficient suppressed π–π interactions. On the contrary, when the side chains are too long, van der Waals forces become predominant and the melting of the compound is dominated by the melting of the side chains, which occurs at higher temperature with increasing chain length iii) Saturation of the Side Chain : For the same main chain length, unsaturated alkyl chains were found to induce lower viscosity than saturated ones.…”

“…To address this issue, we established design principles for kinetically stable LMLs by clarifying the correlation between two molecular structure parameters (side chain–π content ratio and π‐skeleton structure) and the kinetic stability of the corresponding LMLs using alkylated 9,10‐diphenylanthracene as a model LML molecule . A series of alkylated 9,10‐diphenylanthracene derivatives was prepared by modifying Guerbet alcohol‐based alkyl side chains on the 3,5‐positions of the phenyl rings in 9,10‐diphenylanthracene.…”

“…Once enveloped by suitable side chains, various luminescent dyes can be made liquid, with their intense emission maintained in the solvent‐free neat state. To date, deep‐blue‐emitting Naphs , blue‐emitting Fluos , DPAs , OPVs , Pys , azaacenes, blue‐green‐emitting Pys and TPEs , green‐emitting OPEs , orange‐emitting TTZs , and red‐emitting BZTs have been reported.…”