Two Cholesterol-Containing Pyrene Derivatives: Subtle Spacer Difference, Diverse Stimuli-Responsive Luminescence, Chirality, and Self-Assembly Behaviors

Abstract

Two chiral molecules 1 and 2 were designed and synthesized with a pyrene moiety directly linked to a chiral cholesterol moiety and connected through a methylene spacer, respectively. Influence of the spacer on their stimuli-responsive luminescence, chirality, and self-assembly behaviors was systematically investigated. Molecules 1 and 2 had similar aggregation-induced emission enhancement (AIEE) in solution, because of carrying the same fluorescence moiety. Both molecules displayed mechanochromism (MC) property but with different color contrast, whereas only 2 showed mechanoluminescence (ML) activity. When doping in liquid crystal molecule 5CB, both molecules induced the formation of chiral nematic liquid crystals (N*-LCs) with strong circularly polarized luminescence (CPL). Molecule 2 induced single handedness signal, irrespective of doping ratios, while 1-doped N*-LCs showed an inversion of CPL signal from negative to positive upon the increase of doping ratios. Molecules 1 and 2 also self-assembled into different coassemblies with 5CB. Their distinct behaviors were attributed to the influence of the methylene spacer, which caused different molecular conformation and steric bulkiness; accordingly, it changed intermolecular interactions and molecular packing of the two molecules and led to diverse chirality and luminescence. This work provided important model molecules to better understand the molecular structure–property relationship and guide the design of novel functional molecules.

Aggregation behaviour of pyrene-based luminescent materials, from molecular design and optical properties to application

“…94 Pyrene derivatives with planar structures display ML or MC under external stimuli. 56,98 Given pyrene prefers to form a dimer via p-p stacking, the planar pyrene-based intermediate of 4-bpin-2,7-di-tert-butylpyrene 41 99 exhibits a dual emission with monomer-ML and excimer-ML properties, while 2,7-di-tertbutylpyrene 40 and 4-bromo-2,7-di-tert-butylpyrene 42 are ML-active (Fig. 16).…”

Mechanofluorochromic Properties of 1,4-Diphenylanthracene Derivatives with Hypsochromic Shift

“…Mechanofluorochromic materials, which are solid organic light-emitting materials that change their luminous color upon mechanical stimuli by crushing or grinding, have attracted attention for their applications in security inks, memory chips, and pressure sensors [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ]. Numerous organic mechanofluorochromic materials have been reported, including metal complexes [ 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 ], anthracene derivatives [ 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 ], pyrene derivatives [ 66 , 67 , 68 , 69 , 70 ,…”

“…Mechanofluorochromic materials, which are solid organic lightemitting materials that change their luminous color upon mechanical stimuli by crushing or grinding, have attracted attention for their applications in security inks, memory chips, and pressure sensors [20][21][22][23][24][25][26][27][28][29][30]. Numerous organic mechanofluorochromic materials have been reported, including metal complexes [31][32][33][34][35][36][37][38][39][40][41][42][43][44], anthracene derivatives , pyrene derivatives [66][67][68][69][70][71][72][73][74][75][76], tetraphenylethylene derivatives [77][78][79][80][81][82][83], and organoboron compounds [84][85][86][87]…”

Cascade energy transfer augmented circular polarization in photofluorochromic cholesteric texture

“…, cholesteric liquid crystals (CLCs). 13 Moreover, the helical superstructure of CLCs is highly sensitive to external stimuli resulting in valuable regulation of CPL behavior. 14 As shown in Fig.…”