title: Metallacycle-cored supramolecular assemblies with tunable fluorescence including white-light emission.
abstract: Control over the fluorescence of supramolecular assemblies is crucial for the development of chemosensors and light-emitting materials. Consequently, the postsynthetic modification of supramolecular structures via host-guest interactions has emerged as an efficient strategy in recent years that allows the facile tuning of the photophysical properties without requiring a tedious chemical synthesis. Herein, we used a phenanthrene-21-crown-7 (P21C7)-based 60° diplatinum(II) acceptor 8 in the construction of three exohedral P21C7 functionalized rhomboidal metallacycles 1-3 which display orange, cyan, and green emission colors, respectively. Although these colors originate from the dipyridyl precursors 10-12, containing triphenylamine-, tetraphenylethene-, and pyrene-based fluorophores, respectively, the metal-ligand coordination strongly influences their emission properties. The metallacycles were further linked into emissive supramolecular oligomers by the addition of a fluorescent bis-ammonium linker 4 that forms complementary host-guest interactions with the pendant P21C7 units. Notably, the final ensemble derived from a 1:1 mixture of 1 and 4 displays a concentration-dependent emission. At low concentration, i.e., <25 µM, it emits a blue color, whereas an orange emission was observed when the concentration exceeds >5 mM. Moreover, white-light emission was observed from the same sample at a concentration of 29 µM, representing a pathway to construct supramolecular assemblies with tunable fluorescence properties.
authors.affiliation: Department of Chemistry, University of Utah, Salt Lake City, UT 84112.
authors.forename: Mingming
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, University of Utah, Salt Lake City, UT 84112; yinsc@hznu.edu.cn stang@chem.utah.edu.|College of Material, Chemistry and Chemical Engineering, Hangzhou Normal University, Hangzhou 310036, People's Republic of China.
authors.forename: Shouchun
authors.initials: S
authors.lastname: Yin
authors.affiliation: College of Material, Chemistry and Chemical Engineering, Hangzhou Normal University, Hangzhou 310036, People's Republic of China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, University of Utah, Salt Lake City, UT 84112.
authors.forename: Zhixuan
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: Department of Chemistry, University of Utah, Salt Lake City, UT 84112.
authors.forename: Manik Lal
authors.initials: ML
authors.lastname: Saha
authors.affiliation: College of Material, Chemistry and Chemical Engineering, Hangzhou Normal University, Hangzhou 310036, People's Republic of China.
authors.forename: Chenjie
authors.initials: C
authors.lastname: Lu
authors.affiliation: Department of Chemistry, University of Utah, Salt Lake City, UT 84112; yinsc@hznu.edu.cn stang@chem.utah.edu.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Stang
keywords: fluorescence; host–guest interactions; orthogonal interactions; supramolecular metallacycles; white-light emission