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1. Stepwise Generation of Mono‐, Di‐, and Triply‐Reduced Warped Nanographenes: Charge‐Dependent Aromaticity, Surface Nonequivalence, Swing Distortion, and Metal Binding Sites

   https://doi.org/10.1002/ange.202110748  

   Spisak, Sarah N. ; Zhou, Zheng ; Liu, Shuyang ; Xu, Qi ; Wei, Zheng ; Kato, Kenta ; Segawa, Yasutomo ; Itami, Kenichiro ; Rogachev, Andrey Yu. ; Petrukhina, Marina A. ( October 2021 , Angewandte Chemie)

   The stepwise chemical reduction of a molecular warped nanographene (WNG) having a negatively curved π‐surface and defined C₈₀H₃₀composition with Cs metal used as the reducing and complexing agent allowed the isolation of three different reduced states with one, two, and three electrons added to itsπ‐conjugated system. This provided a unique series of nanosized carbanions with increasing negative charge for in‐depth structural analysis of consequences of controlled electron charging of non‐planar nanographenes, using X‐ray crystallographic and computational tools. The 3D molecular electrostatic potential (MEP) maps identified the negative charge localization at the central part of the WNG surface where selective coordination of Cs⁺ions is confirmed crystallographically. In‐depth theoretical investigation revealed a complex response of the WNG to the stepwise electron acquisition. The extended and contorted π‐surface of the WNG undergoes subtle swinging distortions that are accompanied by notable changes in the electronic structure and site‐dependent aromaticity of the resulting carbanions.

    

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2. A multi‐descriptor analysis of substituent effects on the structure and aromaticity of benzene derivatives: π‐Conjugation versus charge effects

   https://doi.org/10.1002/jcc.27296  

   Chagas, Julio C. V. ; Milanez, Bruno D. ; Oliveira, Vytor P. ; Pinheiro Jr, Max ; Ferrão, Luiz F. A. ; Aquino, Adelia J. A. ; Lischka, Hans ; Machado, Franciso B. C. ( December 2023 , Journal of Computational Chemistry)

   This work provides a detailed multi‐component analysis of aromaticity in monosubstituted (X = CH₃, C, C, NH₂, NH⁻, NH⁺, OH, O⁻, and O⁺) andpara‐homodisubstituted (X = CH₃, CH₂, NH₂, NH, OH, and O) benzene derivatives. We investigate the effects of substituents using single‐reference (B3LYP/DFT) and multireference (CASSCF/MRCI) methods, focusing on structural (HOMA), vibrational (AI(vib)), topological (ELF_π), electronic (MCI), magnetic (NICS), and stability (S₀–T₁splitting) properties. The findings reveal that appropriateπ‐electron‐donating andπ‐electron‐accepting substituents with suitable size and symmetry can interact with theπ‐system of the ring, significantly influencingπ‐electron delocalization. While the charge factor has a minimal impact onπ‐electron delocalization, the presence of ap_zorbital capable of interacting with theπ‐electron delocalization is the primary factor leading to a deviation from the typical aromaticity characteristics observed in benzene.

    

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3. A Carbon Nanotube Binding BODIPY‐C 60 Nano Tweezer: Charge Stabilization through Sequential Electron Transfer

   https://doi.org/10.1002/anie.202212474  

   Kazemi, Shahrzad ; Jang, Youngwoo ; Liyanage, Anuradha ; Karr, Paul A. ; D'Souza, Francis ( November 2022 , Angewandte Chemie International Edition)

   Electron donor–acceptor (DA) hybrids comprised of single‐wall carbon nanotubes (SWCNTs) are promising functional materials for light energy conversion. However, the DA hybrids built on SWCNTs have failed to reveal the much‐sought long‐lived charge separation (CS) due to the close proximity of the DA entities facilitating charge recombination. Here, we address this issue and report an elegant strategy to build multi‐modular DA hybrids capable of producing long‐lived CS states. For this, a nano tweezer featuring V‐shape configured BODIPY was synthesized to host SWCNTs of different diameters via π‐stacking. Supported by spectral, electrochemical, and computational studies, the established energy scheme revealed the possibility of sequential electron transfer. Systematic pump‐probe studies covering wide spatial and temporal scales provided evidence of CS from the initial¹BODIPY* ultimately resulting in C₆₀⋅⁻‐BODIPY‐SWCNT⋅⁺CS states of lifetimes in the 20‐microsecond range.

    

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4. A Carbon Nanotube Binding BODIPY‐C 60 Nano Tweezer: Charge Stabilization through Sequential Electron Transfer

   https://doi.org/10.1002/ange.202212474  

   Kazemi, Shahrzad ; Jang, Youngwoo ; Liyanage, Anuradha ; Karr, Paul A. ; D'Souza, Francis ( November 2022 , Angewandte Chemie)

   Electron donor–acceptor (DA) hybrids comprised of single‐wall carbon nanotubes (SWCNTs) are promising functional materials for light energy conversion. However, the DA hybrids built on SWCNTs have failed to reveal the much‐sought long‐lived charge separation (CS) due to the close proximity of the DA entities facilitating charge recombination. Here, we address this issue and report an elegant strategy to build multi‐modular DA hybrids capable of producing long‐lived CS states. For this, a nano tweezer featuring V‐shape configured BODIPY was synthesized to host SWCNTs of different diameters via π‐stacking. Supported by spectral, electrochemical, and computational studies, the established energy scheme revealed the possibility of sequential electron transfer. Systematic pump‐probe studies covering wide spatial and temporal scales provided evidence of CS from the initial¹BODIPY* ultimately resulting in C₆₀⋅⁻‐BODIPY‐SWCNT⋅⁺CS states of lifetimes in the 20‐microsecond range.

    

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5. Charge‐Transport Properties of F 6 TNAP‐Based Charge‐Transfer Cocrystals

   https://doi.org/10.1002/adfm.201904858  

   Dasari, Raghunath R. ; Wang, Xu ; Wiscons, Ren A. ; Haneef, Hamna F. ; Ashokan, Ajith ; Zhang, Yadong ; Fonari, Marina S. ; Barlow, Stephen ; Coropceanu, Veaceslav ; Timofeeva, Tatiana V. ; et al ( October 2019 , Advanced Functional Materials)

   The crystal structures of the charge‐transfer (CT) cocrystals formed by the π‐electron acceptor 1,3,4,5,7,8‐hexafluoro‐11,11,12,12‐tetracyanonaphtho‐2,6‐quinodimethane (F₆TNAP) with the planar π‐electron‐donor molecules triphenylene (TP), benzo[b]benzo[4,5]thieno[2,3‐d]thiophene (BTBT), benzo[1,2‐b:4,5‐b′]dithiophene (BDT), pyrene (PY), anthracene (ANT), and carbazole (CBZ) have been determined using single‐crystal X‐ray diffraction (SCXRD), along with those of two polymorphs of F₆TNAP. All six cocrystals exhibit 1:1 donor/acceptor stoichiometry and adopt mixed‐stacking motifs. Cocrystals based on BTBT and CBZ π‐electron donor molecules exhibit brickwork packing, while the other four CT cocrystals show herringbone‐type crystal packing. Infrared spectroscopy, molecular geometries determined by SCXRD, and electronic structure calculations indicate that the extent of ground‐state CT in each cocrystal is small. Density functional theory calculations predict large conduction bandwidths and, consequently, low effective masses for electrons for all six CT cocrystals, while the TP‐, BDT‐, and PY‐based cocrystals are also predicted to have large valence bandwidths and low effective masses for holes. Charge‐carrier mobility values are obtained from space‐charge limited current (SCLC) measurements and field‐effect transistor measurements, with values exceeding 1 cm²V⁻¹s¹being estimated from SCLC measurements for BTBT:F₆TNAP and CBZ:F₆TNAP cocrystals.

    

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