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Tuning the Electronic Properties and Acid‐Response Behavior of N‐Heteroacene‐Based π‐Conjugated Liquids by Changing the Number of π‐Conjugated Substituents
Author(s) -
Sato Yuika,
Mutoh Yuichiro,
Matsukuma Daisuke,
Nakagawa Makoto,
Kawai Takeshi,
Isoda Kyosuke
Publication year - 2018
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201800631
Subject(s) - conjugated system , thiophene , fluorescence , ring (chemistry) , dissolution , molecule , crystallography , chemistry , pyrazine , phase (matter) , photochemistry , stereochemistry , organic chemistry , polymer , physics , quantum mechanics
We have designed and synthesized two room‐temperature‐fluorescent π‐conjugated liquids based on the N‐heteroacene framework ( 1 and 2 ). These two π‐conjugated liquids, which contained one and two thiophene rings, respectively, exhibited different electronic properties and rheology behaviors. Single‐crystal X‐ray analysis of dithiophene‐appended compound 4 revealed that two thiophene rings hindered the interactions of the imino N atoms with acids through the formation of interactions between the S atoms of the thiophene rings and the imino N atoms of the pyrazine group. On the other hand, monothiophene‐appended molecules 1 and 3 each contained an unhindered imino N atom on the opposite site to the thiophene ring. Upon dissolving various acids with different p K a values in compounds 1 and 2 , these slight structural differences gave rise to marked differences in their acid‐response behaviors, thereby resulting in the emission of variously colored fluorescence in the liquid state. Furthermore, when acids with lower p K a values was dissolved in compounds 1 and 2 , phase transition occurred from an isotropic liquid state to a self‐organized liquid‐crystalline phase.