Angularly fused diaza-dinaphthopyrenes: regio-selective synthesis, crystal structures and isomer-dependent mechanochromic fluorescent properties

Abstract

We report a one-pot synthesis of a series of unprecedented angular-fused diaza-dinaphthopyrene isomers (1,8-DNPy, 1,6-DNPy) in high yields, which are enabled by regio-selective Bischler-Napieralski cyclization to fuse two quinolone rings...

Stimuli-fluorochromic smart organic materials

“…, grinding, pressure, shearing or stretching) is applied, then it is considered to be a piezochromic fluorescent (PCF) material. 37–39,114–117,121–124,225–348 The fluorescence changes can be recovered through recrystallization or heating, during which two different force-dependent stable or metastable states are essential. 55,191 As fluorescence changes can be directly identified by the naked eye, along with the simplified operation conditions, materials exhibiting piezochromic fluorescence hold great potential for applications in strain- or pressure-sensors, flaw detection for surface defects of engineering components, industrial metal products, and security paper.…”

“…There is an unusual example that violates the common mechano-fluorochromic regularity, which is based on planar molecular structures. 124 Specifically, several angular-fused diaza-dinaphthopyrene isomers, 14,17-di(heptan-3-yl)naphtho[1,8- ij :4,5- i ′ j ′]diphenanthridine (1,8-DNPy-B, 32 ) and 6,15-di(heptan-3-yl)naphtho[1,8- ij :5,4- i ′ j ′]diphenanthridine (1,6-DNPy-B, 33 ), were synthesized in one-pot (Fig. 19c).…”

“…Tetraphenylethylene (TPE) derivatives. Since 2010, mechanochromic luminescent materials with various structures have been continuously developed, including TPE derivatives, 34,175,199,214,231,249,253 triphenylamine derivatives, 7,185,200 benzothiadiazole derivatives, 60,151,200,232,332 aromatic imides, 247,283 difluoroboron avobenzone, 228,240,243,277 phenothiazine, 111,140,174,306 molecular rings, 55 polycyclic aromatic hydrocarbons (PAHs), 124 spiropyran derivatives, 219 Rh derivatives, 217,220,258,321 and other molecular structures. 162,217,220,321 Since the aggregation-induced emission (AIE) behavior of TPE was reported by Tang and his coworkers, a large number of TPE-based mechanochromic luminescent materials have been reported.…”

“…Over the last few decades, a myriad of organic π-conjugated solids with diverse stimuli-fluorochromic properties and functions, including SFCSs that are mechano-fluorochromic, 13,14,61,121–124 thermo-fluorochromic, 46,63,64,109,123,125 solvo-fluorochromic, 27,126–131 pH-fluorochromic, 41,47,67,71,108,132 photo-fluorochromic, 133,134 humidity-fluorochromic, 56,63,87,99,107,109,135 electro-fluorochromic, 73–75,136,137 and ion-fluorochromic, 68–70,89,138 have been intensively investigated not only in fundamental research but also in potential applications. 15,16,55,76,87–89,105–110 Fig.…”

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

“…The molecular conformation also plays a significant role to affect the emission behaviour in the solid state. Chen et al 101 reported a one-pot synthetic strategy to access angular-fused diaza-dinaphthopyrene isomers from 2,7-substituted pyrenes, due to the reaction activity in the order of 8- > 6- > 3-positions. Bischler–Napieralski cyclization showed a preference for the 1- and 8-position of pyrene, to achieve the regio-isomers diaza-dinaphthopyrenes 44 and 45 in a ratio of 6:1.…”