01896nas a2200241   4500008004100000022001400041245011600055210006900171260000800240300001100248490000800259520107900267653001301346653001701359653002001376653001901396100001801415700001801433700001801451700002301469700003001492856013201522       2020                        eng d  a0143-720800aTuning phosphorescence features of triphenylamines by varying functional groups and intermolecular interactions0 aTuning phosphorescence features of triphenylamines by varying fu  cFEB  a1079310 v1733 a<p>Organic room temperature phosphorescent materials are known for their synthetic feasibility, tunable phosphorescence wavelength and lifetime, etc. Hence new design strategies have been applied on various fluorophores to improve phosphorescence features. Among those, triphenylamines are phosphorescence active due to the presence of nitrogen atom, propeller molecular structure, and intermolecular interactions in the crystal state. Here we have studied the room temperature phosphorescence of a series of triphenylamines with various functional groups. Detailed studies have shown that the phosphorescence can be fine-tuned by functional group modification. A long phosphorescence lifetime around 100 ms at room temperature in air can be achieved by the interplay of intermolecular interactions, singlet-triplet energy gap and extent of intersystem crossing using functional group variation. Interestingly, an exciplex assisted ultralong phosphorescence lifetime (more than 20 times) is observed for a combination of triphenylamine and naphthalenemonoimide in air.</p>
10aExciplex10afluorescence10aPhosphorescence10atriphenylamine1 aGoudappagouda1 aAsokan, Kiran1 aNayak, Rashmi1 aKrishnan, Retheesh1 aBabu, Sukumaran, Santhosh  uhttps://library.ncl.res.in/content/tuning-phosphorescence-features-triphenylamines-varying-functional-groups-and-intermolecular02407nas a2200313   4500008004100000245008500041210007000126260000800196300001500204490000700219520144500226653001401671653000801685653001401693653001701707653002001724653000901744100001801753700002201771700003001793700002401823700002001847700001801867700001901885700001901904700002101923700003001944856011901974       2025                        eng d00aRegioisomeric π-extended nanographene with long-lived phosphorescence afterglow0 aRegioisomeric πextended nanographene with longlived phosphoresce  cFEB  ae2024221250 v643 a<p>
	The cutouts of graphene sheets, particularly those with a nonplanar topology, present vast opportunities for advancement. Even a slight deviation from the planar structure can lead to intriguing (chiro)optical features for helically twisted nanographenes. In this context, we introduce two regioisomeric pi-extended nanographenes that exhibit distinct excited-state characteristics. The helicene structure and the photophysical features can be easily tuned by changing the connecting position of the nanographene to the carbazole core (2,7- and 3,6-). Single-crystal X-ray diffraction analysis confirmed the formation of nanographenes with bent and helical conformations. Both derivatives exhibited thermally activated delayed fluorescence at room temperature and phosphorescence at low temperatures. Notably, the nanographene with the bent structure displayed an impressive red afterglow lasting over 30seconds, in contrast to the very weak afterglow observed in the helical structure. DFT calculations revealed the existence of an isoenergetic higher triplet state (T-8) and comparatively weak spin-orbit coupling (T-1-S-0), thereby enabling the bent nanographene to exhibit a long-lived component and strong afterglow. Our findings highlight the significance of regioisomeric nanographenes with exceptional optical properties and offer a deeper understanding of the structure-property relationship in nonplanar nanographenes.</p>
10aAfterglow10aCPL10aHelicenes10ananographene10aPhosphorescence10aTADF1 aKumar, Viksit1 aVenugopal, Geethu1 aJadhav, Ashok, Badrinaray1 aDongre, Sangram, D.1 aGonnade, Rajesh1 aKumar, Jatish1 aRuer, Paul, C.1 aHupp, Benjamin1 aSteffen, Andreas1 aBabu, Sukumaran, Santhosh  uhttps://library.ncl.res.in/content/regioisomeric-%CF%80-extended-nanographene-long-lived-phosphorescence-afterglow