@article {48734, title = {Donor-acceptor-based two-dimensional polymer as a supercapacitor electrode with long cycling stability}, journal = {New Journal of Chemistry}, volume = {47}, year = {2023}, month = {OCT }, pages = {18049-18054}, type = {Article}, abstract = {

The high demand for energy and energy-storage devices urged organic 2D polymers as a potential candidate in this area. One of the major attractions of 2D polymers in electrochemical applications is their long cycling stability due to their rigid and porous structure. Herein, we developed a 2D polymer comprised of donor-acceptor units exhibiting reasonably good performance as a supercapacitor. The 2D polymer displayed a maximum specific capacitance of 218 F g-1 at a current rate of 0.1 A g-1, a higher power density of 4648.35 W kg-1, and an energy density of 7.05 W h kg-1. In a cycling stability test, it demonstrated a capacitance retention of 70\% over 10 000 continuous charge-discharge cycles at a current rate of 2.5 A g-1. Such long cycling stability was attributed to the donor-acceptor units and the crystalline nature of the polymer. The sensible selection of the building blocks of the 2D polymers is crucial for the performance and hence provides scope for improvement. An organic donor-acceptor-based 2D polymer, a promising candidate for energy storage devices, displays a specific capacitance of 218 F g-1, a power density of 4648.35 W kg-1, an energy density of 7.05 W h kg-1, and a capacitance retention of 70\% over 10 000 cycles.

}, issn = {1144-0546}, doi = {10.1039/d3nj02510a}, author = {Bhagyasree, T. M. and Puthiyaveetil, Priyanka Pandinhare and Kumar, Viksit and Asokan, Kiran and Sreekumar, K. and Babu, Sukumaran Santhosh} } @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 {48919, title = {Polymerizable solvent-free organic liquids: a new approach for large area flexible and foldable luminescent films}, journal = { Angewandte chemie-international editon }, volume = {62}, year = {2023}, month = {AUG}, type = {Article}, abstract = {

The high demand for light-emitting and display devices made luminescent organic materials as attractive candidates. Solvent-free organic liquids are one of the promising emitters among them due to the salient features. However, the inherent limitations of forming sticky and noncurable surfaces must be addressed to become an alternate emitter for large-area device applications. Herein, we functionalized solvent-free organic liquids having monomeric emission in bulk with polymerizable groups to improve the processability. The polymerizable group on carbazole, naphthalene monoimide, and diketopyrrolopyrrole-based solvent-free liquid emitters enabled on-surface polymerization. These emitters alone and in combinations can be directly coated on a glass substrate without the help of solvents. Subsequent photo or thermal polymerization leads to stable, non-sticky, flexible, foldable, and free-standing large-area films with reasonably high quantum yield. Our demonstration of the tunable and white light-emitting films using polymerizable solvent-free liquids might be a potential candidate in flexible/foldable/stretchable electronics. The new concept of polymerizable liquid can be extended to other functional features suitable for futuristic applications.

}, keywords = {Energy Transfer, polymerization, Solvent-Free Organic Liquids, Thin-Film, White Light}, issn = {1433-7851}, doi = {10.1002/anie.202307381}, author = {Wakchaure, Vivek Chandrakant and Veer, Sairam Dnyaneshwar and Nidhankar, Aakash D. and Kumar, Viksit and Narayanan, Aswini 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 {49327, title = {Extrusion 3D printing of intrinsically fluorescent thermoplastic polyimide: revealing an undisclosed potential}, journal = {POLYMERS}, volume = {16}, year = {2024}, month = {OCT}, type = {Journal Article}, keywords = {Additive manufacturing, functional extrusion, high-performance polymers, thermoplastic polyimide}, doi = {10.3390/polym16192798}, author = {Kothavade, Premkumar and Kafi, Abdullah and Dekiwadia, Chaitali and Kumar, Viksit and Sukumaran, Santhosh Babu and Shanmuganathan, Kadhiravan and Bateman, Stuart} } @article {49318, title = {Tailoring helical ends of π-extended [6]heterohelicenes to control optical, and electrochemical features}, journal = {Chemical Communications}, volume = {60}, year = {2024}, month = {OCT }, pages = {11944-11947}, type = {Article}, abstract = {

The inherent helical chirality and improved pi-stacking capabilities endow helicenes with fascinating photophysical characteristics when decorated with lateral pi-extensions. Here, we report the synthesis and physicochemical characterization of expanded hetero[6]helicenes fused with thiadiazole and selenadiazole rings at the helical ends. Comparing these heterohelicenes revealed the impact of the heteroatom-embedded aromatic rings on the excited state and redox features. A small structural variation of the terminal rings from thiadiazole to selenadiazole caused a striking change in the heterohelical nanographenes. The inherent helical chirality and improved pi-stacking capabilities endow helicenes with fascinating photophysical characteristics when decorated with heteroatoms.

}, issn = {1359-7345}, doi = {10.1039/d4cc03707c}, author = {Kumar, Viksit and Dongre, Sangram D. and Venugopal, Geethu and Narayanan, Aswini and Babu, Sukumaran Santhosh} } @article {49786, title = {Accessing electron-deficient π-extended pyrenes via non-K-region fusion}, journal = {ORGANIC LETTERS}, volume = {27}, year = {2025}, month = {NOV }, pages = {12270-12275}, type = {Article}, abstract = {

This study presents a new class of pyrene derivatives featuring non-K-region fusion and electron-deficient pi-extension. By strategically introducing electron-withdrawing groups at the non-K positions, the optical and redox properties of these compounds were significantly altered. For the first time, we report a non-K-region fused acceptor pyrene with an extended pi-skeleton. The detailed characterizations revealed pronounced shifts in both absorption and emission spectra, accompanied by a significant lowering of the LUMO energy levels. Our results highlight non-K region-fused pyrenes as a promising building block for next-generation organic semiconductors with tunable electronic properties.

}, issn = {1523-7060}, doi = {10.1021/acs.orglett.5c03796}, author = {Dongre, Sangram D. and Kumar, Viksit and Kumar, Ravi and Babu, Sukumaran Santhosh} } @article {49899, title = {(Chiro)optical Properties of π-Extended Spiro-Double Carbo[7]helicene}, journal = {Journal of Physical Chemistry Letters}, volume = {16}, year = {2025}, month = {NOV }, pages = {11657-11664}, type = {Article}, abstract = {

Helical nanographenes are a fascinating class of pi-extended chiral nanocarbons, where structural helicity imparts intrinsic chirality and unique optoelectronic properties to the rigid carbon framework. In this work, we synthesized a hexa-peri-hexabenzocoronene-based pi-extended spiro-double carbo[7]helicene. The helical distortion of the structure was unambiguously confirmed by X-ray crystallography. The optical properties were explored through UV-Vis absorption, fluorescence, and phosphorescence measurements, complemented by density functional theory (DFT) calculations. Remarkably, the pi-extended spiro-double carbo[7]helicene exhibited thermally activated delayed fluorescence (TADF) at room temperature and phosphorescence at low temperatures. Chiral HPLC successfully resolved the enantiomers into three fractions: (PP), (MM), and the meso forms (PM)/(MP), and chiroptical studies of the pure enantiomers revealed a moderately high g lum value of 1.58 x 10-3. Finally, the origin of the observed dissymmetry factors was rationalized by analyzing the transition electric dipole moments (TEDM) and transition magnetic dipole moments (TMDM) derived from time-dependent density functional theory (TD-DFT) calculations.

}, issn = {1948-7185}, doi = {10.1021/acs.jpclett.5c02897}, author = {Kumar, Viksit and Dongre, Sangram D. and Vandhanam, Aparna and Jadhav, Ashok Badrinarayan and Kumar, Jatish and Babu, Sukumaran Santhosh} } @article {49607, title = {Chiroptical amplification of [7]-helicene nanographene by additional helical chirality}, journal = {Angewandte Chemie-International Edition}, volume = {64}, year = {2025}, month = {FEB }, pages = {e202420767}, type = {Article}, abstract = {

Nanographenes have captivated scientific interest since the pioneering discovery of graphene. Recently, attention has shifted towards exploring chiral and nonplanar nanographenes, for their distinct optical, chiroptical, and electronic properties. Despite the growing acceptance of helicenes, the research on inducing helical chirality on pi-extended derivatives to boost chiroptical properties remains unattended. In our study, we introduce a new pi-extended [7]-helicene resulting from the condensation of diamines with 3,6-dibromophenanthrene-9,10-dione, complemented by two hexabenzocoronene arms in the periphery. Notably, the nanographene containing binaphtho-[1,4]diazocine, compared to the corresponding phenazine, exhibits a remarkable average 2.5, 5, and 10-fold enhancements in quantum yield, dissymmetry factor, and brightness, respectively, when measured in five different solvents. These improvements underscore the significance of the induced helical chirality by the antiaromatic binaphtho-[1,4]diazocine in influencing the chiroptical properties of the helical nanographene. Our research represents a significant stride toward unlocking the potential of pi-extended helicenes and lays the groundwork for further exploration in designing and synthesizing new chiral nanomaterials.

}, keywords = {circularly polarised luminescence, dissymmetry factor, helicene, nanographene, quantum yield}, doi = {10.1002/anie.202420767}, author = {Dongre, Sangram D. and Venugopal, Geethu and Kumar, Viksit and Badrinarayan Jadhav, Ashok and Kumar, Jatish and Babu, Sukumaran Santhosh} } @article {49687, title = {Diamondoid all-carbon porous aromatic framework host for lithium-sulfur batteries}, journal = {Small}, volume = {21}, year = {2025}, month = {JUN}, pages = {2500388}, type = {Article}, abstract = {

Lithium-sulfur batteries (LSBs) hold incredible potential as next-generation energy storage systems. However, practical applications of LSBs are significantly hindered by several critical challenges. For the first time, scalable all-carbon porous 3D polymers (3DPs) that do not contain heteroatoms or functional groups and do not require post-functionalization are investigated as hosts in lithium-sulfur batteries, demonstrating enhanced cycling stability and overall battery performance. The pyrene-containing 3DP exhibits 75\% capacity retention after 600 cycles at 1 C and 52\% capacity retention after 1300 cycles at 0.2 C, better than phenyl comprising 3DP. Furthermore, even at higher sulfur loading (4.1 mg cm(-2)) with an electrolyte/sulfur ratio of 5 mu L mg(-1), pyrene 3DP displayed a high capacity of 600 mA h g(-1) and stable performance over 250 cycles with negligible capacity fade. The defined pore structure of 3DPs prevents the migration of polysulfides through physical confinement and the large pi -clouds of 3DPs interact with the negative charge-bearing polysulfides generated in charge-discharge cycles through anion-pi interaction. In this way, The design ensures that the host 3DPs interact with neutral sulfur and anionic polysulfides, resulting in an excellent performance.

}, keywords = {3D polymers, Batteries, Li-Sulfur battery, porous materials, pyrene}, issn = {1613-6810}, doi = {10.1002/smll.202500388}, author = {Kumar, Viksit and Javaregowda, Bharathkumar H. and Devasia, George and Narayanan, Aswini and Krishnamurty, Sailaja and Krishnamoorthy, Kothandam and Babu, Sukumaran Santhosh} } @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} }