title: Naphthalene-Functionalized, Photoluminescent Room Temperature Ionic Liquids Bearing Small Counterions.
abstract: Obtaining π-conjugated room temperature ionic liquids (RTILs) is difficult because of the relatively strong π-π interaction among the π-moieties. Existing strategies by using bulky counterions greatly hindered further property optimization and potential applications of these intriguing functional fluids through simple ion exchange. Herein, four naphthalene-functionalized, π-conjugated RTILs with small counterions (Br(-) ) have been facilely synthesized with high yields. Our strategy is to attach branched alkyl chains to the cationic backbone of the target compounds (2 a-d), which effectively tune inter- and intramolecular interactions. Compounds 2 a-d have satisfactory thermal stability (up to 300 °C) and low melting points (<-19 °C). Rheological measurements revealed the fluid character of 2 a-d, whose viscosity decrease with the increase of the alkyl chain length and temperature. The presence of the π-conjugated naphthalene moiety imparts 2 a-d photoluminescent properties in bulk solutions. Moreover, the absence of strong π-π stacking among the naphthalene units in solvent-free states enables them to be used as a new generation of photoluminescent inks.
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry & Key Laboratory of Special Aggregated Materials, Ministry of Education, Shandong University, Jinan, 250100, Shandong Province, China.
authors.forename: Hongxia
authors.initials: H
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry & Key Laboratory of Special Aggregated Materials, Ministry of Education, Shandong University, Jinan, 250100, Shandong Province, China.
authors.forename: Geping
authors.initials: G
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry & Key Laboratory of Special Aggregated Materials, Ministry of Education, Shandong University, Jinan, 250100, Shandong Province, China.
authors.forename: Mengjun
authors.initials: M
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Solid Lubrication & Laboratory of Clean Energy Chemistry and Materials, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000, Gansu Province, China.
authors.forename: Shengju
authors.initials: S
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry & Key Laboratory of Special Aggregated Materials, Ministry of Education, Shandong University, Jinan, 250100, Shandong Province, China.
authors.forename: Guihua
authors.initials: G
authors.lastname: Li
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry & Key Laboratory of Special Aggregated Materials, Ministry of Education, Shandong University, Jinan, 250100, Shandong Province, China.
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry & Key Laboratory of Special Aggregated Materials, Ministry of Education, Shandong University, Jinan, 250100, Shandong Province, China.
authors.forename: Qingzeng
authors.initials: Q
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Solid Lubrication & Laboratory of Clean Energy Chemistry and Materials, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000, Gansu Province, China. hgli@licp.cas.cn.
authors.forename: Hongguang
authors.initials: H
authors.lastname: Li
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry & Key Laboratory of Special Aggregated Materials, Ministry of Education, Shandong University, Jinan, 250100, Shandong Province, China. jhao@sdu.edu.cn.
authors.forename: Jingcheng
authors.initials: J
authors.lastname: Hao
keywords: branched alkyl chains; imidazole; ionic liquids; naphthalene; photoluminescence