Intramolecular Triple Cyclization Strategy for Sila‐ and Oxa‐Analogues of Truxene with Long‐Lived Phosphorescence

Abstract

Trisilatruxene and trioxatruxene were synthesized by intramolecular triple cyclization of triphenylbenzene derivatives. The results of photophysical studies with these substances show that absorption, fluorescence, and phosphorescence of trisilatruxene appear at longer wavelengths compared to those of hexamethyltruxene. The results of DFT calculations suggest that these effects are a consequence of a decrease in the energy of the LUMO caused by σ*–π* orbital interactions in the silole rings. In contrast, trioxatruxene absorbs and emits light at shorter wavelengths than those of hexamethyltruxene as a result of aromatic stabilization of the furan rings. Moreover, all of the truxenes display long‐lived phosphorescence with lifetimes in the range of 4.4–16.4 s, attributable to the symmetry‐forbidden nature of T1→S0 transitions essentially linked with the C3‐symmetric structures.

Optoelectronic and charge‐transport properties of truxene, isotruxene, and its heteroatomic (N, O, Si, and S) analogs: A DFT study

“…These experimental results suggest that asymmetric isomers are always red‐shifted than their corresponding symmetric isomers. Ogaki synthesized compounds TO and TSi by intramolecular triple cyclization of triphenylbenzene derivatives, and they reported absorption for TO and TSi are at 293 and 310 nm, respectively . To the best of our knowledge, there is no experimental report available on photophysical properties of ITO , ITSi , ITS , and TS .…”

“…Other analogs of T are oxatruxene ( TO ), silatruxene ( TSi ), and thiatruxene ( TS ), which are also synthesized, and their photophysical properties (except TS ) are reported in the literature . To the best of our knowledge, very few reports are available in the literature on TO , TSi , and TS , and these molecules are not yet explored for material properties, as shown in Scheme …”

“…Both the above‐studied molecules T and TN are planar π‐extended electron‐rich molecules, which make these molecules have great potential application in DSSCs, field‐effect transistors (FETs), OLEDs, two‐photon absorption (TPA), and organic laser and fluorescent sensors . Other analogs of T are oxatruxene ( TO ), silatruxene ( TSi ), and thiatruxene ( TS ), which are also synthesized, and their photophysical properties (except TS ) are reported in the literature . To the best of our knowledge, very few reports are available in the literature on TO , TSi , and TS , and these molecules are not yet explored for material properties, as shown in Scheme …”

Toward Soluble 5,10-Diheterotruxenes: Synthesis and Reactivity of 5,10-Dioxatruxenes, 5,10-Dithiatruxenes, and 5,10-Diazatruxenes

“…Truxenes are a family of heptacyclic carbo- and heteroaromatic systems. Currently, the synthesis of truxene 1 − 5 and its triheteroanalogues 6 − 9 as well as their reactivity 10 − 20 are well known. In the 80s, the liquid crystal properties of some alkyl derivatives invoked an interest in this class of substances, in particular, of truxene, 21 , 22 5,10,15-trioxatruxene, 23 and 5,10,15-trithiatruxene.…”

“…Truxenes are a family of heptacyclic carbo- and heteroaromatic systems. Currently, the synthesis of truxene − and its triheteroanalogues − as well as their reactivity − are well known. In the 80s, the liquid crystal properties of some alkyl derivatives invoked an interest in this class of substances, in particular, of truxene, , 5,10,15-trioxatruxene, and 5,10,15-trithiatruxene. , Currently, truxenes are used in optoelectronics as blue emitters, − or in lasing media − and exhibit nonlinear properties. − For example, the use of 5,10,15-triazatruxene as a donor subunit in the D-A 3 system significantly reduced the time of thermally activated delayed fluorescence (TADF) .…”