bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Metallofullerenes, Fullerenes, and Fullertubes: Prediction of Structure Based on Anisotropic Polarizability and Chromatographic Retention Behavior
Authors: Liu Xiaoyang , Bourret Emmanuel , Cover Kevin , Stevenson Steven , Dorn Harry
Published: September 2023

Today, computed structures of fullerenes and fullertubes are readily obtained from Fowler’s spiral program.1 In addition, DFT parameters for fullerenes and fullertubes are readily calculated for these molecules, such as, UV-vis, Raman, and Polarizability. Especially important in this regard is their polarizability and anisotropic polarizability because they are related to the experimental HPLC chromatographic retention time and capacity factor, k′. Kappes and coworkers have mathematically described the effect of polarizabilities, dipole moments, and ionization potentials on these molecules.2 For fullerenes and metallofullerenes, the polarizability is directly proportional to the experimental chromatographic retention parameter, ln(tr/to). Further work by Sabirov3 indicates that anisotropic polarizability is an even better parameter for establishing subtle differences in fullerene structure. In 2021, Stevenson’s laboratory discovered a chemical separation approach that removes from consideration spheroidal and ellipsoidal fullerene cages leaving only tubular fullerenes or “fullertubes.”4 In this presentation, we will show examples where structure determination can begin and end with chromatographic retention time data coupled with DFT calculated parameters for pristine fullertubes, C100-C180.

References:

Fowler, Patrick W., and D. E. Manolopoulos. An Atlas of Fullerenes. Clarendon Press-Oxford, 1995.

Fuchs, D.; Rietschel, H.; Michel, R. H.; Fischer, A.; Weis, P.; Kappes, M. M. Extraction and chromatographic elution behavior of endohedral metallofullerenes: Inferences regarding effective dipole moments. J. Phys. Chem. 1996, 100 (2), 725−72

Sabirov, D. S. The C70 Fullerene Adducts with Low Anisotropy of Polarizability are More Efficient Electron Acceptors for Organic Solar Cells. The Minimum Anisotropy Hypothesis for Efficient Isomer-Free Fullerene-Adduct Photovoltaics. J. Phys. Chem. 2016, 120 (43), 24667−24674.

Stevenson, S.; Liu, X.; Sublett, D. M., Jr; Koenig, R. M.; Seeler, T. L.; Tepper, K. R.; Franklin, H. M.; Wang, X.; Huang, R.; Feng, X.;et al, Semiconducting and Metallic [5,5] Fullertube Nanowires: Characterization of Pristine D5h(1)-C90 and D5d(1)-C100. J. Am. Chem. Soc., 2021, 143 (12), 4593−4599.
(Invited) Anisotropic Contributions in the Chromatographic Elution Behavior of Fullerenes and Fullertubes
Authors: Bourret Emmanuel , Côté Michel , Stevenson Steven
Published: September 2023

Since their discovery in the mid-1980s, the fullerenes have been confined to molecules of less than 100 atoms. With the recent development of a method allowing the isolation of pristine samples[1], the discovery of increasingly long fullertubes, hybrid between a fullerene and a nanotube, is stimulating renewed interest in the field of fullerene science. The increase in the number of atoms comes at a price, the explosion in the number of possible isomers, among which we must identify the experimentally isolated structure. Fuch’s model[2] is commonly used to explain the interaction between fullerenes and non-polar HPLC columns. Still, this approach cannot always differentiate between isomers as the results depend only on the average polarizability, which varies little for fullerenes with the same number of carbon atoms.

In this presentation, we will discuss the use of polarizability anisotropy to differentiate isomers in the context of chromatographic elution. It allows us to generalize Fuchs’ model by adding anisotropic contributions leading to a finer description of fullerenes elution behavior and a better isomeric identification.

[1] R.M. Koenig, H.-R. Tian, T.L. Seeler, K.R. Tepper, H.M. Franklin, Z.-C. Chen, S.-Y. Xie, and S. Stevenson, J. Am. Chem. Soc. 142, 15614 (2020).

[2] D. Fuchs, H. Rietschel, R.H. Michel, A. Fischer, P. Weis, and M.M. Kappes, J. Phys. Chem. 100, 725 (1996).

Figure 1
(Invited) Reactive Oxygen Generation from Photoexcited Fullerene-Peptide Conjugates
Authors: Ma Yue , Persi Lorenzo , Yamakoshi Yoko
Published: September 2023

Fullerenes have been considered as excellent candidates for photosensitizers (PSs) in photodynamic therapy (PDT). Fullerenes are reported to generate reactive oxygen species (ROSs), through energy transfer (singlet oxygen 1O2, Type II reaction) and electron transfer (reduced active oxygen radicals such as superoxide anion radical O2-• and hydroxyl radical •OH, Type I reaction) in an effective way (Figure 1a).1,2 In our previous study, we reported the synthesis of fullerene-PEG conjugates and demonstrated their ability for photoinduced DNA damage and ROS generation upon visible light irradiation.2

In this work, we report the synthesis of a highly water-soluble fullerene-peptide conjugate. The fullerene-peptide conjugates are well-dispersed in aqueous media in comparation to fullerene-PEG conjugates, as indicated by dynamic light scattering (DLS) measurement as well as cryo-TEM microscopy. The ROSs generation capacity of fullerene-peptide conjugate, detected by electron paramagnetic resonance (EPR), DNA damage and in vitro photocytotoxicity tests will also be presented.

Figure 1
(Invited) Conducting the Scholl Reaction: Spironanographenes Vs Helically Arranged Nanographenes
Authors: Izquierdo-García Patricia , Fernández-García Jesús Manuel , Martín Nazario
Published: September 2023

The stepwise synthesis of graphene molecular fragments, molecular nanographenes (NGs), allows the design and monodisperse preparation of sophisticated molecules with perfectly defined shapes and properties.1 The introduction of defects to the honeycomb pattern allows the preparation of nanographenes with finely tunable characteristics, as chirality. Helicenes and non-hexagonal rings are the most usual motifs to this end, as they generate axial chirality by diverting the structures from the 2D plane.

In 2021 we reported a new family of molecular nanographenes in which the axial chirality results from the helical arrangement of the graphitized moieties covalently connected through a tetrafluorobenzene core 1.2 Although two enantiomers were confirmed by x-ray diffraction and chiral HPLC, racemization was observed.3 The isomerization process was evaluated, and the isomerization barrier resulted of ∆G≠= 24.6 kcal/mol at 40 ºC, which corresponds to a half-life time of t½ = 107 min.

In order to modulate both optoelectronic and chiroptical properties we decided to increase the rigidity of the structure by introducing a 9,10-anthracene as central core. However, unexpected spironanographene 2 was obtained during the key step in the synthesis of nanographenes, the Scholl reaction. Under different reaction conditions we were able to obtain spirocompounds with different graphitization degree. Herein we reported the first spirocycles formation under Scholl reaction conditions without interrupting the graphitization process.4 To further understand the formation of the unexpected nanographenes, theoretical calculations were carried out and revealed the formation of a trityl cation that is involved in the formation of the spirocycles.

Furthermore, in order to conduct the reaction towards the formation of the expected rigid helically arranged nanographene, an electron deficient core was designed. The substitution of the central anthracene with eight electron withdrawing fluorine atoms destabilizes the trityl cation and the expected helically arranged nanographene 3 was obtained.4

[1] Y. Gu, K. Müllen. J. Am.
Chem. Soc.
2022
, 144, 11499–11524.

[2] P. Izquierdo-García, J. M. Fernández-García, I. Fernández, J. Perles, N. Martín. J. Am. Chem. Soc. 2021, 143, 11864–11870.

[3] J. M. Fernández-García, P. Izquierdo-García, M. Buendía, S. Filippone and N. Martín. Chem. Commun. 2022, 58, 2634-2645.

[4] P. Izquierdo-García, J. M. Fernández-García, J. Perles, I. Fernández, N. Martín. Manuscript in preparation.

Figure 1
(Invited) Stereoselective Synthesis of Molecular Nanographenes
Authors: Martin Nazario , Buendía Manuel , Marcos Sergio , Filippone Salvatore
Published: September 2023

The precise control of stereogenic elements in chemical structures has always been a higly demanding synthetic task.1 In this regard, most of the currently available asymmetric methods require the presence of a heteroatom in the starting substrates that serves as an anchoring point for the successful transfer of chiral information. This eventually emerges, typically, in the form of a new stereogenic centre while the heteroatom remains in the product. This general procedure could account for the lack of stereoselective protocols in all-carbon atom compounds.2,3 Actually, optically active nanographenes have so far been obtained only by either top-down or bottom-up racemic syntheses, followed by time consuming chiral chromatographic separations.4-6 In this presentation, we will introduce a general overview on the efforts carried out in our group in the search for stereoselectivity to introduce and extend stereogenic elements into polyaromatic sp2 carbon-based molecular nanographenes.

Acknowledgements

The author acknowledge support from the MICIN of Spain (project: PID2020-114653RB-I00) and the European Research Council (ERC) Synergy Grant “TOMATTO” (Project 951224).

References

H. Kuang, C. Xu, Z. Tang, “Emerging Chiral Materials”, Adv.
Mater.
2020, 32, e2005110.

M. Rickhaus, M. Mayor, M. Juricek, “Strain-induced helical chirality in polyaromatic systems”, Chem.
Soc. Rev.
2016, 45, 1542-1556.

J. M. Fernández-García, P. Izquierdo-Garcia, M. Buendia, S. Filippone, N. Martín, “Synthetic chiral molecular nanographenes: the key figure of the racemization barrier”, Chem. Commun.
2022,
58, 2634-2645.

P. J. Evans, J. Ouyang, L. Favereau, J. Crassous, I. Fernández, J. Perles-Hernáez, N. Martín "Synthesis of a Helical Bilayer Nanographene" Angew. Chem. Int. Ed. 2018, 57, 6774 –6779.

P. Izquierdo-García, J. M. Fernández-García, I. Fernández, J. Perles, N. Martín, “Helically Arranged Chiral Molecular Nanographenes", J. Am. Chem. Soc., 2021, 143, 11864−11870.

M. Vázquez-Nakagawa, L. Rodríguez-Pérez, N. Martín, M. A. Herránz, “Supramolecular Assembly of Edge Functionalized Top-Down Chiral Graphene Quantum Dots”, Angew. Chem. Int. Ed. 2022, 61, e202211365.
(Invited) Fullerenes in Water: The Formation of Hydrogels
Authors: Porfyrakis Kyriakos
Published: September 2023

Hydrogels are emerging as important materials to achieve medical advances, in applications such as cellular scaffoldings in regenerative medicine/tissue engineering, tissue replacements, wound dressings, and drug/gene/protein/RNA delivery systems among others. This is due to their high-water content and their similarities to the structural form of living tissues. Hydrogels are most useful when they can be compatible with the dynamics of healthy tissues, while at the same time they are able to deliver therapeutic molecules at specified locations.

In this talk, I will present our recent work in using fullerenes and their derivatives for biomedical engineering. Fullerenes are attractive for a number of reasons: their surface can be functionalised to enhance their biocompatibility and water solubility; they can encapsulate molecules in endohedral form, and they have shown antiviral, antibacterial and antioxidant activity. The physical properties of fullerenes make them ideal candidates to produce supramolecular structures and hydrogels without the need for an external polymeric matrix. I will show the synthesis of supramolecular hydrogels solely from covalently-functionalised C60. I will also demonstrate the synthesis of new kinds of supramolecular hydrogels made from fullerenes of different sizes (C60, C84 and C90–92) functionalised with hydrophilic oligoethylene glycol chains. Carrying out the reaction on fullerenes of different sizes, including C70, allows us to interrogate the effect of fullerene shape on chemical functionalization, and thus, self-assembly behaviour.

We believe these fullerene hydrogels may have biomedical applications. Furthermore, they maybe sought after for electrochemical applications such as next-generation capacitors.
(Invited) 2D Nitride Mxenes with Unusual Chemistries for Carbon-Neutral Energy
Authors: Djire Abdoulaye
Published: September 2023

The large-scale shift towards renewable energy technology requires the ability to reliably convert and store electrochemical energy. This technology is still limited in terms of performance, cost, and/or ease of utilization. In recent years, two-dimensional (2D) materials have been explored as low-cost, high-performing catalysts and electrodes for the reliable conversion and storage of electrochemical energy. Of these 2D materials, a special class of carbides and nitrides, known as MXenes, have gained popularity due to their high tunability, conductivity, and high surface area-to-volume ratio. From these carbide and nitride MXenes, the nitrides have received less attention due to a lack of reliable synthesis methods, despite being theorized to outperform their carbide counterparts. In this presentation, I will present on the oxygen-assisted molten salt fluoride synthesis method developed in my group to produce phase-pure nitride MXenes. Along with this, I will provide evidence of the enhanced capabilities of the nitride family of MXenes compared to carbides, sulfides, and oxides, when applied in the nitrogen reduction reaction (NRR), hydrogen evolution reaction (HER), and supercapacitor applications. In each of these fields, the enhanced performance is investigated using in-situ/operando spectroelectrochemical techniques. I will wrap up by discussing the future directions in the field of MXenes that require further attention for the full exploitation of their properties in electrochemical energy storage and conversion systems to attain carbon-neutral energy.
DNA Linked Mixed-Dimensional Heterostructures: The Designing, Nanoscale Control and Device Applications of Tmdc-Quantum Dot Nanohybrids
Authors: Chen Kai , Talha-Dean Teymour , Zheng Tingting , Dimitrov Stoichko , Mol Jan , Palma Matteo
Published: September 2023

DNA Linked Mixed-Dimensional Heterostructures: the Designing, Nanoscale Control and Device Applications of TMDC-Quantum Dot Nanohybrids

Kai Chen,a Teymour Talha-Dean,b Tingting Zheng, a Stoichko Dimitrov, a Jan Mol b and Matteo Palma a

aDepartment of chemistry, Queen Mary University of London, London E1 4NS, United Kingdom

bDepartment of Physics, Queen Mary University of London, London E1 4NS, United Kingdom

The construction of mixed-dimensional heterostructures is a promising approach for the development of biosensing and optoelectronic systems and devices. The accurate nanoscale control of the heterostructures interface is a key challenge, for instance to tune the distance between the individual components and their stoichiometry, that in turn affect their electronic coupling. In this regard, DNA can be a powerful structural and functional linker for nano-hybrids assembly, due to its tunability down to sub-nanometer control.

Our current interest is focused on the fabrication of TMDC-based nanohybrids using double stranded (ds) DNA as both a linker and templating moiety. In particular, we recently employed three different approaches to functionalize the surface of MoS2 nanoflakes and assembled 0D (quantum dots)/2D (MoS2 flakes) hybrids using DNA as a connection moiety (see figure).[1] DNA allowed us to control the distance between QDs and MoS2 with sub-nanoscale accuracy, allowing the fine tuning of the electronic coupling between the two nanostructures.

We will further discuss the construction of mixed-dimensional nanohybrids i) via the use different DNA nanotechnology strategies, and ii) for the fabrication of responsive optoelectronic devices.

[1] T. Talha-Deam, K. Chen, G. Mastroianni, F. Gesuele, J. Mol and M. Pamla. “Nanoscale Control of DNA-Linked MoS2-Quantum Dot Heterostructures”. Bioconjugate Chemistry, 2022, DOI: 10.1021/acs.bioconjchem.2c00285
Amplification-Free Detection of Sars-Cov-2 and Respiratory Syncytial Virus Using CRISPR Cas13a and Graphene Field-Effect Transistors
Authors: Li Huijie , Zhang Yi
Published: September 2023

The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) systems have recently received notable attention for their applications in nucleic acid detection. Despite many attempts, the majority of current CRISPR-based biosensors in infectious respiratory disease diagnostic applications still require target preamplifications. This study reports a new biosensor for amplification-free nucleic acid detection via harnessing the trans-cleavage mechanism of Cas13a and ultrasensitive graphene field-effect transistors (gFETs). CRISPR Cas13a-gFET achieves the detection of SARS-CoV-2 and respiratory syncytial virus (RSV) genome down to 1 attomolar without target preamplifications. Additionally, we validate the detection performance using clinical SARS-CoV-2 samples, including those with low viral loads (Ct value >30). Overall, these findings establish our CRISPR Cas13a-gFET among the most sensitive amplification-free nucleic acid diagnostic platforms to date.
(Invited) Unraveling Electron-Phonon Coupling in 2D Materials in Momentum and Time with Ultrafast Electron Diffuse Scattering (UEDS)
Authors: Siwick Bradley John
Published: September 2023

The nature of the couplings within and between lattice and charge degrees of freedom is central to an understanding of electrical and heat transport in materials. These interactions are essential to phenomena as diverse as superconductivity, charge density waves and carrier mobility in semiconductors and metals. Despite their fundamental role, detailed momentum-dependent information on the strength of electron-phonon coupling (EPC) and phonon-phonon coupling (PPC) across the entire Brillouin zone has proved to be very difficult to obtain.

I will describe an emerging pump-probe technique, ultrafast electron diffuse scattering (UEDS), that provides such information from the perspective of the phonon system directly. Recent examples of the application of UEDS to layered (2D) materials will be the focus. First, in the thermoelectric material SnSe – a strongly polar semiconductor – we directly observe the phonon dressing processes that yield carrier localization and polaron formation with UEDS. In SnSe these phonon dressing dynamics are profoundly bimodal, with the fast (300 fs) process associated with the formation of a quasi-1D lattice distortion and a relatively large polaron and the slower (4 ps, an order of magnitude slower timescale) process associated with small polaron formation. The observations in SnSe are consistent with electron and hole polarons being different sizes, or the process of polaron formation being instrincially bimodal for both carriers in a manner reminiscent of Lars Onsager’s inverse snowball effect. Second, the extension of UEDS to a MoS2 monolayer heterostructure will be demonstrated. These results reveal substrate dielectric screening of the electron-phonon interaction within the monolayer as well as the monomentum-dependent carrier-phonon equilibration. These results are compared directly against ab-initio simulations of these processes

Figure 1
Van der Waals Interaction Mediated Redox on Graphene Electrode
Authors: Saraf Ravi , Saraf Akshat , Lim Jay Min
Published: September 2023

Graphene, unlike (defective) graphene oxide, is generally not considered to be a highly efficient electrochemical electrode except for activity at the edges. This is because, graphene forms a highly stable hydration bilayer that screens the electric field emanating from the electrode to drive the electrochemical process. A remarkable electrochemical electrode property of graphene is discovered and explored. The property emerges from graphene’s single crystal, aromatic structure. The redox behavior of an aromatic compound, methylene blue (MB) and non-aromatic compounds, such as , potassium ferric cyanide are compared. The electrochemical behavior on monolayer of graphene is quantitatively measured by a novel opto-electrochemical instrument for both electrochemical and structural information. The instrument called, the Scanning Electrometer for electrical Double-layer (SEED) allows local measurement of redox on a 10 micron laser spot to exclusively measure redox signal away from the edges of graphene. Two distinct peaks for both reduction and oxidation during conventional cyclic voltametric (CV) waveform are observed by SEED (Figure 1). The two peaks were attributed to two distinct orientation of MB chemisorption on graphene and subsequent electron transfer. One of the peak depended on precise orientation of the MB on single crystal graphene surface indicating pi-pi interaction mediated chemisorption (Figure 2). The other peak is independent of graphene orientation. MB redox on Au showed a single peak (Figure 1) and was independent of orientation (Figure 2). The effect of the two modes of chemisorption on ionic strength was studied and compared with MB redox on pure gold performed on the same chip. The two peaks were not distinguishable by CV or differential pulse voltammetry (DPV) measured on the same sample under similar conditions. This indicated the sensitivity of SEED to obtain structural information and its ability to measure electrochemical activity on micro-spot. All the three measurements, SEED, DPV and CV were performed without taking the sample out of the solution. The redox of non-aromatic compounds showed no orientation effect. The distinct van der Waals interaction mediated chemisorption by pi-pi stacking on graphene electrode may have distinct advantage to design highly sensitive and specific sensors and biosensors in future, for example, in DNA and RNA sensing.

Figure 1
Advanced Characterization by Using Coupled Operando Mass Spectrometry and Operando Dilatometry
Authors: Petit Jan , Heugel Philipp , Joos Martin , Klein Franziska , Tübke Jens
Published: September 2023

Mechanical modifications or harmful side reactions are undesirable ageing effects that can occur during cycling. These phenomena have a negative impact on cell performance and consequently limit cycle life. The focus here is on investigations of ageing processes such as volume changes and electrolyte decomposition during cycling.

Combined thickness measurements and gas analytical studies of Li-Graphite half cells with a carbonate-based electrolyte are presented. In addition, the same measurements on Li-O2 cells with an ether-based electrolyte are introduced. The electrolytes consist of 1M LiPF6 in EC:DMC (1:1, wt) and 1M LiTFSI in DEGDME, respectively. All measurements were carried out using specially developed multifunctional test setups and accordingly modified test cells. The different cell specifications were examined by operando mass spectrometry (MS) and operando dilatometry. In addition, post-mortem gas chromatography-mass spectrometry (GC-MS) was conducted.

Application-oriented analysis such as gas analysis, thickness measurements or both combined are suitable methods to define operating parameter, to benchmark and to identify decomposition reactions. Operando electrochemical dilatometry was conducted to check whether an irreversible increase in thickness occurred. On the corresponding cell configurations, the dilatation was recorded over the entire electrode stack as well as of the separate working electrode only. Furthermore, operando MS can be used to detect gaseous substances produced by (electro)chemical processes as a function of the state of charge. With the GC-MS, a post-mortem analysis was performed to identify the individual substances qualitatively.

Results of the different cell specifications are shown and can be compared with each other. A detailed relationship can be demonstrated between the change in thickness and the potential profile. Moreover, the cyclic formation of several degradation products is detected. Possible correlations between gas evolution and thickness changes can be shown.

In conclusion, these analytical studies provide a new important contribution to get a more detailed insight into ageing processes that take place. The possible coupling of two operando techniques enables an even more holistic examination to analyze cell performance.

Parts of the presented work are supported by the Fraunhofer and Max-Planck cooperation program in the project “Clusterbatt” together with Fraunhofer IWS, Dresden and MPIKG, Potsdam. Parts of the presented work are funded by the German Federal Ministry of Education and Research (BMBF) in the joint German-Japanese project “OsabanPlus” (03XP0469C) together with Justus-Liebig-University Giessen, TU Braunschweig and University of Kyoto.

Figure 1
Thermal Degradation of Polycrystalline Ni-Rich Cathodes, New Insights from Total Scattering and Machine-Learning Assisted Tomography
Authors: Hou Dong , Xiao Xianghui , LIU Jue , Zhou Xiao-Dong , Yang Zhijie , Xu Zhengrui , Lin Feng
Published: September 2023

Alkali metal-based batteries (e.g., lithium batteries) are considered the most effective energy storage candidate for portable electronics, power grids, and electric vehicles due to their considerable energy density, power density, cycle life, safety, and competitive prices. The Ni-rich Co-less ternary LiNi
x
Mn
y
Co1-x-y
O2 (NMC) (Ni>80%) is one of the candidate materials due to its high discharge capacity (>200 mAh g-1) and high energy density (>750 Wh kg-1). However, the thermal stability of charged Ni-rich NMCs is inferior, following a general negative correlation between Ni content and stability. Such severer degradation in Ni-rich NMCs might lead to dysfunctionality, thermal runaway, and eventually catastrophic failure and explosion of batteries, raising enormous safety concerns. Therefore, it is critical to understand the thermal behavior of charged Ni-rich NMC cathode from different perspectives in order to conduct material design for better thermal stability.

After literature survey of typical and widely used probes by this community (e.g., diffraction, spectroscopy, imaging), we found these approaches subject to compromise to some degree in the experimental design, resulting in an inadequate description of the thermal degradation mechanism. Here we offer two novel approaches, neutron total scattering and energy-resolved 3D nano-tomography, to probe the reaction and evolution of the charged NMCs under non-ambient conditions in real-time. Such in situ measurements were only accomplished by deliberate experimental design at beamlines and deep integrations of neutron or synchrotron facilities with battery science. In situ heating neutron scattering captures the transition of crystal structure in reciprocal space (by Rietveld refinements), as well as of the local atomic framework in real space (by pair distribution function analysis). Moreover, machine learning algorithms were applied to the 3D nano-tomography datasets to reveal the detailed microstructural and oxidation state progression inside the charged particles. Thereafter, we discussed the key factors which have previously been overlooked by the community and offer constructive suggestions on particle design for thermally stable cathodes from our unique perspective.

The work was supported by the National Science Foundation under Grant no. DMR-1832613 (F.L.). The machine-learning assisted tomography analysis was partially supported from NASA under 80NSSC21M0333 and NSF under NSF-2119688 (X.-D.Z)
(Invited) Chiral Perovskite Nanocrystals Growth inside Helical Hollowsilica Nanoribbons
Authors: Oda Reiko , Liu Peizhao , Battie Yann , Kimura Takaki , Pranee Piyanan , Okazaki Yutaka , Wang Hao , Pouget Emilie , Nlate Sylvain , Sagawa Takashi
Published: September 2023

Nanometric silica helical ribbons are used as platforms 1) to graft Perovskyte nano crystals and 2) grow in-situ Perovskyte crystals having helical shape using supersaturated recrystallization method. For both systems, they show strong induced circular dichroism (CD) and induced circularly polarized luminescence (CPL) signals, with very high dissymetric g-factors. The signs of these signals depend on the handedness of the helices. Right-handed and left-handed PNCs show respectively positive and negative CD and CPL signals. Simulations based on the boundary element method demonstrate that the circular dichroism comes from the chiral shape of H-PNCs.

Figure 1
(Invited) Ternary-Cascaded Triplet Energy Landscape for Solid-State Photon Upconversion
Authors: Tamai Yasunari
Published: September 2023

Here, we introduce a new strategy for improving the efficiency of solid-state photon upconversion based on triplet–triplet exciton annihilation (TTA-UC). We designed a ternary blend system consisting of a triplet sensitizer (TS), an exciton-transporting host polymer, and a small amount of an annihilator. The key idea underpinning this concept involves sequential triplet energy transfer from the TS to host and then to the annihilator, driven by the cascaded triplet energy landscape. Because of the small annihilator blend ratio, the local density of triplet excitons in the annihilator domain is higher than the overall density, leading to faster TTA. Based on the excitation-intensity and blend-ratio dependences of TTA-UC efficiency, we found that our concept has a positive impact on accelerating TTA.
(Invited) Structural and Dynamics Analysis of Organic Semiconducting Materials by Solid State NMR
Authors: Suzuki Katsuaki , Kaji Hironori
Published: September 2023

Recently, our group have successfully developed several blue and green thermally activated delayed fluorescence (TADF) emitters showing high external quantum efficiencies in OLEDs through high-throughput screening based on quantum chemical calculations. Although the conformation, aggregated structure and dynamics of TADF emitters in amorphous states is expected to be the origin of reverse intersystem crossing and resulting high device performance, the experimental approach toward these information is still limited because typical diffraction technique cannot be used to amorphous materials due to the lack of long-range order. Thus we have carried out multiscale simulations and solid-state NMR (ssNMR) analysis of organic amorphous thin films. The ssNMR is one of the powerful technique to obtain the structural and dynamics information of amorphous aggregated materials. In this presentation, we demonstrate structural and dynamics analysis of amorphous organic semiconducting materials using ssNMR.

Reference

(1) “Analysis of Molecular Orientation in Organic Semiconducting Thin Films Using Static Dynamic Nuclear Polarization Enhanced Solid-State NMR Spectroscopy”, Suzuki, K.; Kubo, S.; Aussenac, F.; Engelke, F.; Fukushima, T.; Kaji, H. Angew. Chem. Int. Ed. 2017, 56, 14842.

(2) “Efficient blue thermally activated delayed fluorescence emitters showing very fast reverse intersystem crossing”, Ren, Y., Wada, Y., Suzuki, K., Kusakabe, Y., Geldsetzer, J. and Kaji, H.

Appl. Phys. Express, 2021, 14, 071003.

(3) “Solution-processable thermally activated delayed fluorescence emitters for application in organic light emitting diodes”, Suzuki, K.; Adachi, C.; Kaji, H. J. Soc. Inf. Disp.
2017, 25, 480.

(4) “Imidazole Acceptor for Both Vacuum-Processable and Solution-Processable Efficient Blue Thermally Activated Delayed Fluorescence”, Kusakabe, Y.; Wada, Y.; Misono, T.; Suzuki, K.; Shizu, K.; Kaji, H

ACS Omega, 7, 16740 - 16745 (2022).

(5) “Triarylboron-based Fluorescent Organic Light-emitting Diodes with External Quantum Efficiencies Exceeding 20%”, Suzuki, K.; Kubo, S.; Shizu, K.; Fukushima, T.; Wakamiya, A.; Murata, Y.; Adachi, C.; Kaji, H.; Angew. Chem. Int. Ed. 2015, 54, 15231.

(5) “Purely organic electroluminescent material realizing 100% conversion from electricity to light”, Kaji, H.; Suzuki, H.; Fukushima, T.; Shizu, K.; Suzuki, K.; Kubo, S.; Komino, T.; Oiwa, H.; Suzuki, F.; Wakamiya, A.; Murata, Y.; Adachi, C. Nat. Commun. 2015, 6, 8476.
(Invited) Synthesis of Multi-Metallic Nanocatalysts Using a Dendrimer Reactor
Authors: Yamamoto Kimihisa
Published: September 2023

Dendrimers are highly branched organic macromolecules with successive layers or “generations” of branch units surrounding a central core. Organic inorganic hybrid versions have also been produced, by trapping metal ions or metal clusters within the voids of the dendrimers. Their unusual, tree-like topology endows these nanometer-sized macromolecules with a gradient in branch density from the interior to the exterior, which can be exploited to direct the transfer of charge and energy from the dendrimer periphery to its core.

We show that AuCl3, SnCl2, FeCl3, and so on complexes to the imines groups of a spherical polyphenylazomethine dendrimer in a stepwise fashion according to an electron gradient, with complexation in a more peripheral generation proceeding only after complexation in generations closer to the core has been completed. By attaching an electron-withdrawing group to the dendrimer core, we are able to change the complexation pattern, so that the core imines are complexed last. By further extending this strategy, it should be possible to control the number and location of metal ions incorporated into dendrimer structures, which might and uses as tailored catalysts, building blocks, or fine-controlled clusters for advanced materials. The metal-assembly in a discrete dendrimer molecule can be converted to a size-regulated metal particle with a size smaller than 1 nm as a molecular reactor(Fig.). Due to the well-defined number of metal clusters in the subnanometer region, its property is much different from that of bulk or general metal nanoparticles. The chemistry of nanocatalysts on the sub-nanometer scale is not yet well understood because precise multi-metallic nanoparticles are difficult to synthesize with control over size and composition. The template synthesis of multi-metallic sub-nanocalaysts is achieved using a phenylazomethine dendrimer as a macromolecular template.

Figure 1
Exploring Unconventional Electrolytes to Tackle the Problem of Shuttling in Precipitation-Dissolution Battery Chemistries
Authors: Yao Koffi Pierre , Taiwo Gbenga
Published: September 2023

A1-Triple I: Any galvanic cell functions by compartmentalizing, via the electron-blocking electrolyte, an exothermic chemical reaction into two redox half-reactions to force release of the reaction free energy as electrical energy. The conventional electrolyte is an ion-conductor shuttling the operative ions and preventing any other chemical exchange to maintain the integrity and reversibility of the electrodes. In overcoming the capacity ceiling of layered intercalation hosts, conversion reactions between low-cost chalcogens (sulfur, selenium, and oxygen) and alkali metals (lithium and sodium) have been investigated for decades. However, parasitic crossover of soluble polychalcogenides limit battery cycle life. We conceptualize that selective solute transport at the interface of partially miscible solvents can be utilized in designing organic electrolytes to suppress parasitic crossover in precipitation-dissolution battery chemistries. This talk will discuss successful concept-demonstration experiments and highlight intriguing physical phenomena within such electrolyte system under the dynamics of electrochemistry.
Effects of Operating Temperature on Li-O2 Battery with Ionic Liquid-Based Binary Electrolyte
Authors: Zaidi Syed Shoaib Hassan , Kore Rajkumar , Shiflett Mark , Li Xianglin
Published: September 2023

The progress of rechargeable Li-O2 battery (LOB) is hampered due to the number of challenges its components present. Among various critical challenges, the choice of electrolyte has always been a bottleneck impeding the breakthrough in the development of LOB. Various electrolytes, including organic solvents and room-temperature ionic liquids (RTILs) have been developed and studied. Each electrolyte comes with various limitations, which restrict its application in the LOB. These include thermal and electrochemical stability, volatility, viscosity, flammability, capability to dissolve incoming oxygen, diffusivity, and ionic conductivity. Consequently, no electrolyte could be regarded as an ideal electrolyte. Nonetheless, efforts have been made to tune the physiochemical properties of the electrolyte by blending two or more miscible solvents. High thermal and electrochemical stability and negligible volatility of RTILs can be combined with high diffusivity and ionic conductivity of organic solvents by merely blending them with optimized volume ratios.

In this study, we comprehensively investigated the effects of operating temperature (20°C, 40°C and 60°C) on the electrochemical performance of LOBs incorporated with RTIL and organic solvent binary electrolyte. We designed and investigated, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2C1im][Tf2N]) RTIL and dimethyl sulfoxide (DMSO) organic solvent at various volume ratios ((4:1), (1:1), (1:4)). Among the binary electrolytes, ([C2C1im][Tf2N]/DMSO (1:4)) delivered the highest discharge capacities of 3.70 Ah g-1 (20°C), 4.0 Ah g-1 (40°C) and 3.65 Ah g-1 (60°C) as compared with pure [C2C1im][Tf2N] and DMSO. Cycling stability tests showed superior stability of the binary electrolyte ([C2C1im][Tf2N]/DMSO (1:4)) irrespective of the operating temperature. From viscosity and ionic conductivity measurements (at 20-60°C), [C2C1im][Tf2N]/DMSO (1:4) exhibited the highest ionic conductivity and the lowest viscosity compared with other binary electrolytes and pure RTIL at any given temperature. Cyclic voltammetry (CV) tests revealed a higher reaction rate with [C2C1im][Tf2N]/DMSO (1:4) binary electrolytes than pure electrolytes. The superior performance of [C2C1im][Tf2N]/DMSO (1:4) binary electrolyte was ascribed to enhanced stability against reactive intermediate species during oxygen reduction reaction (ORR), increased ionic conductivity, low viscosity (comparable with organic electrolytes), improved oxygen solubility, and relatively low evaporation rates. The detailed results and discussion will be presented during the presentation.
Low Voltage Electrochemical Aqueous Hydrogen Storage
Authors: Wang Taobo , Xi Dawei , Aziz Michael J.
Published: September 2023

Recent years have witnessed the hydrogen production techniques being cheaper and greener. Therefore, as the mass use of hydrogen in energy applications is revisited, hydrogen storage became an important part of the supply chain. However, safety concerns of compressed gas storage made it impossible for mass hydrogen storage in places like airports and industries. By using an aqueous quinone-based flow battery setup operated under room temperature, hydrogen can be stored up to 2.5 M, which is in equivalent to a 56-atm gas tank in terms of hydrogen density. The release of hydrogen can be achieved at 0.25 V and a roundtrip energy requirement for < 7 kWh/kgH2. The Coulomb efficiency for 100 mA/cm^2 cells is at 99.8% and the fade rate of AQDS is around 0.1%/day. This work aims to find a way of safe and cost-efficient hydrogen storage and raises some possibilities of the design for next-generation hydrogen storage techniques.
Electronic Structure, Spectroscopy, and Redox Properties of Highly Soluble (μ-oxo)Bis[Tetra(tert-butyl)(phthalocyaninato)Iron(III)] Complex and Its Pyridine Adduct Under Anaerobic Conditions in Non-Coordinating Solvents
Authors: Nemykin Viktor
Published: September 2023

The solid-state Mössbauer spectra of a highly soluble (μ-oxo)bis[tetra(tert-butyl)(phthalocyaninato)iron(III)] complex 1 ((PctBuFe)2O) consist of two doublets that represent bent geometry μ-oxo(1) (1a, ΔEQ = 0.43 mm/s, T = 10K) and linear geometry μ-oxo(2) (1b) isomers (ΔEQ = 1.40 mm/s, T = 10K) with the ratio between two isomers depending on the purification method. Both isomers were found to be diamagnetic and transform entirely in 1a isomer in solution. The room- and low-temperature MCD spectra of 1a show one Faraday A- and one B-terms between 670 and 720 nm, which correlate with the 690 nm band and 709 nm shoulder observed in the UV-Vis spectrum of this compound. UV-Vis and MCD spectra of 1a are independent of the temperature. Both 1a and 1b are diamagnetic between room temperature and 4 K. Electrochemical experiments show up to three oxidation and up to four reduction processes in 1a. Its oxidation under spectroelectrochemical or chemical (in the absence of oxygen-containing oxidants) oxidation conditions in non-coordinating solvents results in the formation of a broad NIR band around 1195 nm (first oxidation) and 1264 nm (second oxidation). The MCD spectra of the redox-active species show a Faraday B-term signal with negative amplitude in this region and are very different from those in monomeric PctBu(1-)FeIIIX2 complexes 5X (X = Cl- or CF3CO2
-). Pyridine adduct of 1a ((PyPctBuFe)2O; 2Py) is paramagnetic (μB = 2.19, g = 2.11, and J = -6.1cm-1) and has a major peak at 627 nm in UV-Vis spectrum, which is associated with MCD pseudo A-term. Density Functional Theory (DFT) and Time-Dependent DFT (TDDFT) calculations, along with Kasha’s and Spano’s exciton coupling theories, were used to explain unusually red-shifted intense transitions in 1a as well as H-aggregate like spectra of the pyridine adduct 2Py.
Supramolecular Helical Polymer Formed Via Complementary Dimerization of Bisporphyrin Cleft
Authors: Haino Takeharu
Published: September 2023

We have been developing supramolecular polymers directed by unique host-guest motifs.1,2 During study, a tetrakisporphyrin monomer was discovered to form the supramolecular helical polymers.3,4 A lack of chirality resulted in the racemic mixture of the supramolecular helical polymers. In this presentation, we report that the chirally-twisted pseudo macrocyclic tetrakisporphyrin monomer is self-assembled to form the one-handed helical supramolecular structures. Two amino acid side chains were installed at the termini of a tetrakisporphyrin monomer. The intramolecular antiparallel hydrogen bonding between the amino acid side chains resulted in the pseudo macrocyclic conformation, which was chirally-twisted. The right-handed and left-handed conformations of the pseudo macrocyclic monomer are determined by the absolute configuration of the stereogenic centers. The chirally-twisted pseudo macrocyclic monomer was self-assembled to result in the one-handed helical structures with very high association constants. The well-developed supramolecular chains generated entangled polymer solution, which suggests the formation of the well-developed long supramolecular polymer chains. Atomic force microscopy visualized the long supramolecular polymer chains with the length more than 100 nm. The right-handed helical morphology was formed from the D-amino acid side chains.

References:

Haino, T., Polym. J., 2013, 45, 363-383.

Haino, T., Chem. Rec., 2015, 15, 837-853.

Haino, T., Fujii, T., Watanabe, A., Takayanagi, U., Proc. Natl. Acad. Sci. USA, 2009, 106, 10477-10481.

Nadamoto, K., Maruyama, K., Fujii, N., Ikeda, T., Kihara, S.-I., Haino, T., Angew. Chem. Int. Ed., 2018, 57, 7028-7033.
A Rational Strategy to Assemble Porphyrins and Phthalocyanins into Crystalline Arrays: The SURMOF Approach
Authors: Woell Christof
Published: September 2023

Realizing molecular “Designer Solids” by programmed assembly of building units taken from libraries is a very appealing objective. Recently, metal-organic frameworks (MOFs), or porous coordination polymers (PCPs) have attracted a huge interest in this context. Here, we will focus on MOF-based electrochemical, photoelectro-chemical, photovoltaic, and sensor devices built using porphyrin- and phthalocyanine-containing linkers. Internal interfaces in MOF heterostructures are also of interest with regard to photon-upconversion and the fabrication of diodes.

Since the fabrication of reliable and reproducible contacts to MOF-materials represent a major challenge, we have developed a layer-by-layer (lbl) deposition method to produce well-defined, highly oriented and monolithic MOF thin films on appropriately functionalized substrates. The resulting films are referred to as SURMOFs [1,2] and have very appealing properties in particular with regard to optical applications [3]. The fabrication of hetero-multilayers is rather straightforward with this lbl method. In this talk, we will describe the principles of SURMOF fabrication as well as the results of systematic investigations of electrical and photophysical properties exhibited by empty MOFs and after loading their pores with functional guests. Band structure effects occurring in crystalline porphyrin arrays assembled using the SURMOF approach will also be discussed. [5] We will close with discussing further applications [4] realized by loading MOFs with nanoparticles or quantum dots and by creating molecular solids lacking inversion symmetry for second harmonic generation (SHG).[5]

In the last part of the presentation we will point out that SURMOFs are very well suited for unattended experimentation approaches. Using robot systems controlled by machine learning (ML) algorithms allows to efficiently optimize thin film properties (orientation, crystallinity, roughness). We will discuss this point in particular in connection with the fabrication of SURMOF-based sensor systems.

References:

[1] J. Liu, Ch. Wöll, Chem. Soc. Rev., 2017, 46, 5730-5770

[2] L. Heinke, Ch. Wöll, Adv. Mater., 2019, 31 (26), 1970184

[3] R. Haldar, L. Heinke, Ch. Wöll, Adv. Mater., 2020, 32, 1905

[4] A. Chandresh, X. Liu, Ch. Wöll, L. Heinke, Adv. Sci., 2021, 8, 2001884

[5] J. Liu, W. Zhou, J. Liu, I. Howard, G. Kilibarda, S. Schlabach, D. Coupry, M. Addicoat, S. Yoneda, Y. Tsutsui, T. Sakurai, S. Seki, Z. Wang, P. Lindemann, E. Redel, Th. Heine, Ch. Wöll, Angew. Chemie Int. Ed., 2015, 54, 7441

[6] A. Nefedov, R. Haldar, Zh. Xu, H. Kühner, D. Hofmann, D. Goll, B. Sapotta, S. Hecht, M. Krstić,

C. Rockstuhl, W. Wenzel, S. Bräse, P. Tegeder, E. Zojer, Ch. Wöll, Adv. Mater., 2021, 33, 2103287

Figure 1