Ring-in-Ring(s) Complexes Exhibiting Tunable Multicolor Photoluminescence

Published on 2020-09-16T14:09:39Z (GMT) by
One ring threaded by two other rings to form a non-intertwined ternary ring-in-rings motif is a challenging task in noncovalent synthesis. Constructing multicolor photoluminescence systems with tunable properties is also a fundamental research goal, which can lead to applications in multidimensional biological imaging, visual displays, and encryption materials. Herein, we describe the design and synthesis of binary and ternary ring-in-ring(s) complexes, based on an extended tetracationic cyclophane and cucurbit[8]­uril. The formation of these complexes is accompanied by tunable multicolor fluorescence outputs. On mixing equimolar amounts of the cyclophane and cucurbit[8]­uril, a 1:1 ring-in-ring complex is formed as a result of hydrophobic interactions associated with a favorable change in entropy. With the addition of another equivalent of cucurbit[8]­uril, a 1:2 ring-in-rings complex is formed, facilitated by additional ion–dipole interactions involving the pyridinium units in the cyclophane and the carbonyl groups in cucurbit[8]­uril. Because of the narrowing in the energy gaps of the cyclophane within the rigid hydrophobic cavities of cucurbit[8]­urils, the binary and ternary ring-in-ring(s) complexes emit green and bright yellow fluorescence, respectively. A series of color-tunable emissions, such as sky blue, cyan, green, and yellow with increased fluorescence lifetimes, can be achieved by simply adding cucurbit[8]­uril to an aqueous solution of the cyclophane. Notably, the smaller cyclobis­(paraquat-<i>p</i>-phenylene), which contains the same <i>p</i>-xylylene linkers as the extended tetracationic cyclophane, does not form ring-in-ring(s) complexes with cucurbit[8]­uril. The encapsulation of this extended tetracationic cyclophane by both one and two cucurbit[8]­urils provides an incentive to design and synthesize more advanced supramolecular systems, as well as opening up a feasible approach toward achieving tunable multicolor photoluminescence with single chromophores.

Cite this collection

Wu, Huang; Wang, Yu; Jones, Leighton O.; Liu, Wenqi; Song, Bo; Cui, Yunpeng; et al. (2020): Ring-in-Ring(s)

Complexes Exhibiting Tunable Multicolor

Photoluminescence. ACS Publications. Collection. https://doi.org/10.1021/jacs.0c07745