@article { ISI:000339729400018, title = {CVD synthesis of graphene nanoplates on MgO support}, journal = {Materials Science-Poland}, volume = {32}, number = {2}, year = {2014}, month = {JUN}, pages = {243-246}, publisher = {OFICYNA WYDAWNICZA POLITECHNIKI WROCLAWSKIEJ}, address = {WYBRZEZE WYSPIANSKIEGO 27, 50-370 WROCLAW, POLAND}, abstract = {

Synthesis of graphene directly on MgO has been carried out and the structural properties of the obtained material have been investigated. Few-layered graphene was produced by simple thermal decomposition of methane over MgO powder at 950 A degrees C in a CVD reactor. The samples were purified by 10 N HNO3 treatment, and studied by TEM, Raman spectroscopy, EDAX and SEM. TEM clearly indicated the formation of graphene. EDAX showed that the purified sample contained only carbon and no traces of MgO. The characteristic Raman features of graphene were also seen as D-band at 1316 cm(-1), G-band at 1602 cm(-1), and a small 2D-band at 2700 cm(-1) in the Raman spectra. The strong D-band suggests that the graphene possess large number of boundary defects. The small 2D-band indicates the formation of few-layered graphene.

}, keywords = {graphene, magnesium oxide, nanographene}, issn = {2083-1331}, doi = {10.2478/s13536-013-0193-6}, author = {Jugade, Ravin M. and Sharma, Shalini and Gokhale, Suresh} } @article {48939, title = {Isomer effect on energy storage of π-extended S-shaped double[6]heterohelicene}, journal = { Angewandte chemie-international edition}, volume = {62}, year = {2023}, month = {NOV}, type = {Article}, abstract = {

Recently, chiral and nonplanar cutouts of graphene have been the favorites due to their unique optical, electronic, and redox properties and high solubility compared with their planar counterparts. Despite the remarkable progress in helicenes, pi-extended heterohelicenes have not been widely explored. As an anode in a lithium-ion battery, the racemic mixture of pi-extended double heterohelical nanographene containing thienothiophene core exhibited a high lithium storage capability, attaining a specific capacity of 424 mAh g-1 at 0.1 A g-1 with excellent rate capability and superior long-term cycling performance over 6000 cycles with negligible fade. As a first report, the pi-extended helicene isomer (PP and MM), with the more interlayer distance that helps faster diffusion of ions, has exhibited a high capacity of 300 mAh g-1 at 2 A g-1 with long-term cycling performance over 1500 cycles compared to the less performing MP and PM isomer and racemic mixture (150 mAh g-1 at 2 A g-1). As supported by single-crystal X-ray analysis, a unique molecular design of nanographenes with a fixed (helical) molecular geometry, avoiding restacking of the layers, renders better performance as an anode in lithium-ion batteries. Interestingly, the recycled nanographene anode material displayed comparable performance. A pi-extended double heterohelical nanographene of thienothiophene core fused with two hexabenzocoronene units exhibits excellent performance as an anode in a lithium-ion battery. The isomer (PP and MM) with more interlayer distance exhibited a high lithium storage capability compared to the other isomer and racemic mixture. Helical nanographene anodes display excellent rate capability, superior long-term cycling performance, and recyclability.image

}, keywords = {Battery, graphene, Li-ion battery, nanographene, Organic Electrode Material}, issn = {1433-7851}, doi = {10.1002/anie.202311657}, author = {Kumar, Viksit and Bharathkumar, H. J. and Dongre, Sangram D. and Gonnade, Rajesh and Krishnamoorthy, Kothandam and Babu, Sukumaran Santhosh} } @article {49100, title = {Boron- and oxygen-doped π-extended helical nanographene with circularly polarised thermally activated delayed fluorescence}, journal = {Chemistry-A European Journal}, volume = {30}, year = {2024}, month = {APR }, type = {Article}, abstract = {

Helical nanographenes have garnered substantial attention owing to their finely adjustable optical and semiconducting properties. The strategic integration of both helicity and heteroatoms into the nanographene structure, facilitated by a boron-oxygen-based multiple resonance (MR) thermally activated delayed fluorescence (TADF), elevates its photophysical and chiroptical features. This signifies the introduction of an elegant category of helical nanographene that combines optical (TADF) and chiroptical (CPL) features. In this direction, we report the synthesis, optical, and chiroptical properties of boron, oxygen-doped pi-extended helical nanographene. The pi-extension induces distortion in the DOBNA-incorporated nanographene, endowing a pair of helicenes, (P)-B2NG, and (M)-B2NG exhibiting circularly polarized luminescence with glum of -2.3x10-3 and +2.5x10-3, respectively. B2NG exhibited MR-TADF with a lifetime below 5 mu s, and a reasonably high fluorescence quantum yield (50 \%). Our molecular design enriches the optical and chiroptical properties of nanographenes and opens up new opportunities in multidisciplinary fields. B, O-doped pi-extended helical nanographene has been explored for its optical and chiroptical properties. The presence of helical and nanographene segments stabilize the helicity and imparts tunable optical properties. Helical nanographene display circularly polarized thermally activated delayed fluorescence. image

}, keywords = {circularly polarized luminescence, DOBNA, dual emission, nanographene, TADF}, issn = {0947-6539}, doi = {10.1002/chem.202304169}, author = {Venugopal, Geethu and Kumar, Viksit and Jadhav, Ashok Badrinarayan and Dongre, Sangram D. and Khan, Abujunaid and Gonnade, Rajesh and Kumar, Jatish and Santhosh Babu, Sukumaran} } @article {49568, title = {Regioisomeric π-extended nanographene with long-lived phosphorescence afterglow}, journal = {Angewandte Chemie-International Edition}, volume = {64}, year = {2025}, month = {FEB}, pages = {e202422125}, type = {Article}, abstract = {

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.

}, keywords = {Afterglow, CPL, Helicenes, nanographene, Phosphorescence, TADF}, doi = {10.1002/anie.202422125}, author = {Kumar, Viksit and Venugopal, Geethu and Jadhav, Ashok Badrinarayan and Dongre, Sangram D. and Gonnade, Rajesh and Kumar, Jatish and Ruer, Paul C. and Hupp, Benjamin and Steffen, Andreas and Babu, Sukumaran Santhosh} }