bluuebunny/crossref_metadata_2025 huggingface dataset:
Representation of Vivid Colors of Cyan, Magenta, Yellow, and Green in Ag Deposition-Based Plasmonic Electrochromic Device By Precise Control of Shape and Density of Deposited Ag Nanoparticles
Authors: Kimura Shunsuke , Sugita Tomoko , Nakamura Kazuki , Kobayashi Norihisa
Published: July 2021

Ag nanoparticles exhibit various colors depending on their localized surface plasmon resonance (LSPR). Based on this phenomenon, Ag deposition-based electrochromic devices can represent various optical states in a single device such as the three primary colors (cyan, magenta, and yellow), silver mirror, black and transparent.1 A control of the morphology of Ag nanoparticles can lead to dramatic changes in color, as their size and shape influence the LSPR band. For this purpose, the “voltage-step method” was applied to a Ag deposition-based EC device to obtain multiple colors by shifting the LSPR band. In this method, two different voltages are successively applied : the first voltage V
1 is applied for a very short time t
1 to initiate Ag nucleation, and the second voltage V
2 is applied for a time t
2 to promote growth of the Ag nuclei. As V
2 is more positive than the nucleation voltage, further nucleation is no longer possible during t
2. Therefore, the Ag nanoparticle growth and the resultant device color can be controlled by changing t
2.

In this study2, we aimed to improve the color quality of Ag deposition-based multicolor EC devices by precisely controlling the supply of Ag+ ions to the electrode surface. Initially, the effect of coloration by decreasing the concentration of Ag+ ions in the Ag deposition-based EC device was investigated. As a result of optimizing the driving voltage, a lower concentration device (10 mM Ag+ ion) showed vivid and bright colors of cyan and magenta. This improvement was due to the generation of fine Ag nanoparticles and the prevention of the connection of Ag particles. From the electrochemical investigation, it was suggested that the slow supply rate of Ag+ ions in the lower concentration device induced electrochemical deposition of fine and isolated Ag nanoparticles.

Consequently, to obtain more uniformly deposited Ag nanoparticles, the nucleation voltage of V
1 was set to a lower voltage in the 10 mM device. As a result, spherical Ag nanoparticles were successfully obtained, and the device showed yellow and green colors. By comparing the LSPR behavior of the device with that of Ag nanoparticles dispersed in solution and using FDTD calculations, the mechanism of the yellow and green colors was investigated in detail. Thus, it indicated that the yellow coloration with an absorption band in the 400–500 nm region was caused by LSPR absorption of isolated spherical Ag nanoparticles. Furthermore, it was also observed that the coexistence of isolated spherical particles and aggregations of Ag nanoparticles induced two types of LSPR bands, leading to a good green color.

References

A.Tsuboi, K.Nakamura and N.Kobayashi, Chem. Mater., 2014, 26, 6477-6485

S.Kimura, T.Sugita, K.Nakamura and N. Kobayashi, Nanoscale, 2020 (in press)
(Invited) A Pure Titania Photocatalyst: Preparation, Characterization and Photocatalytic Activity of Octahedral-Shaped Anatase Particles
Authors: Ohtani Bunsho , Li Yumin , Koike Sayaka , Takashima Mai
Published: July 2021

Different from organic molecules and metal complexes, which can be identified by chemical composition and structural characteristics such as NMR spectra, inorganic solid materials especially metal oxides cannot be identified, i.e., their purity cannot be evaluated in a strict scientific sense, because at least three structural parameters, bulk structure, surface structure and bulk/surface size, must be determined. However, in the other words, solid metal-oxide samples can be assigned to be "pure", if their three parameters are determined, by macroscopic measurements, to be uniform. Here, attempts to prepare octahedral-shaped anatase titanium(IV) oxide (titania) particles (OAPs) of uniform bulk structure (anatase with negligible non-crystalline components), surface structure (only exposing {101} facets) and particle size are reported as the first and sole example of a "pure" metal-oxide powder. In this study, OAP samples were prepared by sonication-hydrothermal (HT) reaction of potassium-titanate nanowires. Characterization of the samples by Rietveld analysis of XRD patterns, reversed double-beam photoacoustic spectroscopy and SEM observations revealed the homogeneousness of crystalline bulk, surface and particle size, respectively, to indicate the samples "pure".
Electrochemical Liquid Liquid Synthesis of Semiconductor and Intermetallic Nanomaterials
Authors: Maldonado Stephen , Wu Henry , Pattadar Dhruba
Published: July 2021

This presentation describes the hybrid methodology of electrochemical liquid-liquid-solid (ec-LLS) crystal growth for the synthesis of semiconductor and intermetallic nanostructures. The premise of ec-LLS is that electrodeposition can be coupled with melt-crystal growth through the use of liquid metal cathodes. Electrodeposition of zero-valent metals and metalloids, followed by dissolution into and then precipitation out of the liquid metal, affords low-temperature and rapid crystal growth. This presentation first describes our latest understanding of the governing factors of ec-LLS processes for the preparation of semiconductor nanowires. Following, our latest results for the synthesis of intermetallic nanoparticles by ec-LLS will be demonstrated. The operative design rules for optimal liquid metal cathodes that afford tailored binary and ternary intermetallic nanoparticles will be discussed. An emphasis will be placed on ec-LLS reactions that produce catalytic intermetallic nanomaterials.
(Invited) Catalyst Design and Development for Highly Selective Photocatalytic Conversion of CO2 By H2o As an Electron Donor
Authors: Teramura Kentaro
Published: July 2021

The reduction in human-induced emissions of CO2 from automobiles, factories, power stations etc., over the next 15 years is currently one of the most important issues facing the planet. We should therefore attempt to develop industrial processes using CO2 as a feedstock to build a sustainable society. Linear CO2 molecules adsorbed on the surface of the solid bases are converted into unique structures, such as bicarbonate and carbonate species possessing lattice oxygen atoms. We believe that the process involves the capture and distortion of CO2 upon adsorption on a solid base through activation by photoirradiation. These days, we succeeded in designing highly selective photocatalytic conversion of CO2 by H2O as the electron donor, by the simultaneous use of an inhibitor of the production of H2 and a material for CO2 capture and storage. An isotope experiment using 13CO2 and mass spectrometry clarified that the carbon source of the evolved CO is not the residual carbon species, but the CO2 introduced in the gas phase. In addition, stoichiometric amounts of O2 were generated together with CO.
Optical and Electronic Properties of Atomically Thin Organic-WSe2 Hybrid Structures
Authors: Ji Jaehoon , Choi Jong Hyun
Published: July 2021

Two-dimensional (2D) transition metal dichalcogenides such as WSe2 have garnered much attention due to their extraordinary layer-number-dependent optoelectronic properties. To exploit the unique properties for novel optoelectronic applications, it is important to construct heterojunctions and understand their layer-number-dependent characteristics. In this work we have investigated heterojunctions made of 2D WSe2 flakes decorated with organic dye molecules elucidated the optical and electronic properties as a function of layer number. We introduce a facile one-step approach to deposit a uniform layer of eosin Y (EY) molecules on various number of WSe2 layers, forming hybrid heterojunctions. Photoconductive atomic force microscopy (PC-AFM), Kelvin probe force microscopy (KPFM), and photoluminescence (PL) spectroscopy probed the organic/inorganic heterojunctions. The hybrid structures show drastically enhanced photocurrents due to the lowered barrier height by the staggered band alignment. The barrier heights of the hybrid structures monotonically decrease as the layer number increases. The surface potential measurements reveal that the work functions of the hybrids are smaller than those of the pristine WSe2 samples. Moreover, the hybrid samples show spatially uniform current and photocurrent responses, indicating the high quality and uniform heterojunctions. Lastly, the hybrid samples show a drastic PL quenching due to p-doing on WSe2. These findings will open new opportunities for novel WSe2-based 2D heterostructured optoelectronics.
(Invited) Ultrafast Excited State Dynamics of Twisted Aromatics
Authors: Hariharan Mahesh
Published: July 2021

Self-assembling of organic chromophoric systems into elegant supramolecular architectures with emergent properties has received prodigious attention in recent years.1 The notion of ‘emergence upon assembly’ is evidenced in the unusual photoexcited state dynamics exhibited by chromophoric assemblies. In the first example, a naphthalene-naphthalimide donor-acceptor (D-A) dyad assembled into segregated D-A stacks in the crystalline state. The photo-induced charge separated state in the aggregate state lasts 10,000 times longer than the monomeric dyad. The femtosecond transient absorption spectra depicted the spectroscopic signature for naphthalene dimer radical cation indicating the migration of charges through the stacks.2 In the second example, we report the crystalline evidence for Greek cross‐dipole (α=90°) stacking of 1,7‐dibromoperylene‐3,4,9,10‐tetracarboxylic tetrabutylester (PTE‐Br2) displaying null excitonic coupling and thereby monomeric optical behavior. Additionally, the semi‐classical Marcus theory of charge‐transfer rates predicted a selective hole transport phenomenon in the orthogonally stacked PTE‐Br2.3 In the third example, we showcase a radial assembly of 1,8-dibromonaphthalene(2,6-diisopropylphenyl)imide (NIBr2) in crystalline phase driven by hexabromine synthon.4 NIBr2 exhibits ultrafast intersystem crossing5 and solid-state room temperature phosphorescence. We believe the fundamental understanding of noncovalent interactions dictating the unorthodox assembly of chromophores6-7 and probing of emergent properties are paramount for the rational design and construction of robust functional materials.8-9

References:

Cheriya, R. T.; Mallia, A. R.; Hariharan, M. Energy Environ. Sci.
2014, 7, 1661.

Mallia, A. R.; Salini, P. S.; Hariharan, M. J.
Am. Chem. Soc.
2015, 137, 50, 15604.

Sebastian, E.; Philip, A. M.; Benny, A.; Hariharan, M. Angew.
Chem., Int. Ed.
2018, 57, 15696.

Niyas, M. A.; Ramakrishnan, R.; Vijay, V.; Sebastian, E.; Hariharan, M. J. Am. Chem. Soc.
2019, 141
, 4536.

Nagarajan, K.; Mallia, A. R.; Muraleedharan, K.; Hariharan, M. Chem. Sci.
2017, 8, 1776.

Ramakrishnan, R.; Niyas, M. A.; Lijina, M. P.; Hariharan, M. Acc. Chem. Res.
2019, 52, 3075-3086.

Mohan, A; Sasikumar, D.; Bhat, V.; Hariharan, M. Angew. Chem., Int. Ed.
2020, 59, 3201-3208.

Sasikumar, D.; John, A. T.; Sunny, J.; Hariharan, M. Chem. Soc. Rev.
2020
, 49, 6122-6140.

Lijina, M. P.; Benny, A.; Ramakrishnan, R.; Nair, N.; Hariharan, M. J.
Am. Chem. Soc.
2020, 142, 41, 17393.

Figure 1
Control of Physicochemical Properties for Thiophene-Fused Naphthodiphospholes By Precise Fusion of Heterole Rings
Authors: Ishida Keiichi , Higashino Tomohiro , Imahori Hiroshi
Published: July 2021

Fused polycyclic aromatics have been vigorously pursued over the years because of their attracting structural, electronic, and photophysical features associated with the rigid and planar π-conjugated frameworks. For polycyclic aromatics with heterole-fused structures, the orientation of fused heterole rings as well as the geometry of their fused structures has a large impact on the physicochemical properties. In this regard, we expected that introducing two phosphorus atoms into polycyclic aromatics would provide an assortment of isomers originated from not only the position and orientation of the phosphole rings, but also the orientation of substituents on the phosphorus atoms (trans/cis configurations). Herein, we designed and synthesized a series of six isomers of thiophene-fused naphthodiphospholes based on our envision. Systematic investigations into the physicochemical properties revealed that the positions of heterole rings are of utmost importance to tune their electronic properties, and the orientations of heterole rings and substituents on the phosphorus atoms play critical roles in the molecular arrangements in the solid states.
On the Optimization of Core-Shell Hybrid Cathode Materials for Extreme Fast-Charging: First Principles Computational Insights
Authors: Yao Koffi Pierre , Mou Rownak Jahan
Published: July 2021

Core-shell and core-gradient hybrid cathode materials for lithium-ion batteries display enhanced rate capability over their homogeneous counterparts. The apparent enhancement of transport is shown to arise from advective flow of Li+ from the higher free-energy core towards the lower free-energy shell compositions. First-principles analysis of a planar model of these hybrid structures concludes that the inbuilt free-energy gradient enhances the Li+ de-intercalation process by reducing the average overpotential during extreme fast-charging. Analysis of representative LiNi0.8Co0.1Mn0.1O2||LiNi0.4Co0.2Mn0.4O2 core/shell reveals: (i) an optimal components ratio exists that maximizes storage capacity during fast-charging and (ii) components should be selected with appreciably large chemical potential difference between the core and shell to further exploit the free-energy gradient effects provided volume ratios are optimized against the potential gradient. In the case of NCM811||NCM424 studied herein, a balanced (ca. 40/60 vol.%) structure appears optimal. This finding indicates that the shell must not necessarily be confined to a thin chemically-protective coating; higher relative volumes of the lower free-energy shell may provide performance benefits at high-rates. The presented insights will serve towards optimizing and developing high capacity, more rate capable core-shell particles for extreme fast charging batteries.

Figure 1
Reserved Lithium-Ion Batteries for in Situ Lithiation of Vanadium Pentoxide Cathode
Authors: Parekh Mihit H. , Palanisamy Manikandan , Pol Vilas G.
Published: July 2021

The race to substitute gasoline-powered vehicles with electric ones has resulted in the boom of electric vehicles’ sales by about 20 times since 2011 till the present. This has triggered a huge supply-demand scenario for lithium-ion batteries (LIBs) around the globe. Currently, LIBs rely heavily on cathodes such as LiNixMnyCozO2, LiFePO4, LiNiO2, LiCoO2, to maintain their place to meet energy expectations. Rarely, lithium-free compounds have been used as positive electrodes due to the irreversibility of redox reactions and the requirement of lithium metal anode. These have restricted the further development of new cathode materials for lithium-ion batteries. Some of the materials are Cr3O4, ZnO, TiO2, MnO2, and V2O5. These materials have high theoretical capacities, however, except V2O5, other materials have a low potential for insertion/extraction of Li+ ions and can possibly be reduced to the metal state during intercalation reactions. To ensure practicality and feasibility of such materials, it is important to focus on the lithiation strategies, viz., lithium additives, pre-lithiation of the anode,film-forming additives, and blended cathodes. However, these approaches cause cell voltage modification due to the presence of Li+ ion voids in the electrode. Fortunately, the pre-lithiation of the anode compensates for the initial loss of lithium ions in the formation of the solid electrolyte interface (SEI). However, the pre-lithiation technique is complex and uneconomical, resulting in it being infeasible in the commercial applications.

Here we report, in situ lithiation of the electrodes for the advancement of the lithium-free cathode research using lithium-electrode as a reservoir. The presence of a third reservoir electrode in LIB is brought only into the cell circuit initially during the SEI formation process and lithiation of the electrode. Here, V2O5 cathode with meso carbon microbeads (MCMB) was used to fabricate high specific capacity and high energy-density reserved lithium-ion batteries (RLIBs). The RLIB system delivered a high charge specific capacity of 245 mAh g-1 following two Li+ ions insertion/extraction. The tri-electrode system provided an initial high energy density of 980 Wh kg-1. A comparison of performance between V2O5 half-cell, V2O5-MCMB full-cell, and RLIB was made. There is a stark resemblance in the performance of RLIB performance with half-cell profile and in terms of capacity versus cycle number. Multiple module calorimetry provided the thermal heat signature to elucidate the safety features of the proposed RLIB system and compare it to the existing LIBs. Using this innovative concept of reservoir charging would be of key importance and valuable for applications in various sectors of society.

Figure 1
Full Parametrisation and Newman Modelling of the Mixed Niobium Oxide - NMC System: Unveiling the Limiting Factor and Tackling Problems with Solid State Diffusion Parametrisation
Authors: Houck Maurits E. , Zhang Wanwei , Geary Harry , Groombridge Alexander S. , De Volder Michael F. L. , Boies Adam M.
Published: July 2021

Over the last decade, Mixed Niobium Oxide (MNO) materials have been widely researched as new lithium-ion battery anode material[1]. Their MO3-x perovskite-like host structure enables faster lithium-ion transport than graphite with higher specific capacities than LTO, while it also has excellent cycle life and voltage window respectively. Recent DFT modelling and in-situ material studies have greatly improved understanding at the material level[2]. However, for full scale implementation, more holistic parametrisation and modelling is needed to further interpret MNO behaviour in full cells, to perform sensitivity analysis for increased life and rate performance, and to design NMC/MNO battery systems. Here, we present one of the first full parametrisations and physics-based Newman models of the NMC/MNO system based on experimental data. The main governing mechanisms in the model are illustrated in Fig. 1.

In particular we focus on parametrisation and modelling of the particle size and solid-state lithium-ion diffusion coefficient. While these are shown to be crucial controlling factors in performance, there is considerable disagreement on definitions and measurement methods of the solid-state lithium-ion diffusion coefficient in literature. Values attained through DFT, PFG-NMR, GITT, EIS and Cyclic Voltammetry differ by orders of magnitude[3,4,5], and there is a knowledge gap between diffusion coefficients determined at the crystal level and at the cell level[6]. Literature on solid-state lithium-ion diffusion theory and measurement techniques is reviewed, and a better approach to parametrisation of solid-state lithium-ion diffusion is presented to improve cell modelling.

The resulting model helps in a more complete understanding of the NMC/MNO system and provides insights in why the NMC/MNO cell has superior properties compared to other cell configurations. It reveals what processes control NMC/MNO cell performance parameters such as polarisation, and therefore directs further research. Finally, it is shown how the model can be used to design new battery applications.

References

[1] Deng, Q. et al., Small 2019, 15, 1804884.

[2] Yuan, T. et al., Energy
Fuels 2020, 34, 11, 13321–13334.

[3] Koçer, C. P. et al., Chem. Mater. 2020, 32, 3980–3989.

[4] Griffith, K. J. et al., J. Am. Chem. Soc 2019, 141, 16706–16725.

[5] Lee, YS. et al., Sci. Rep. 2017, 7, 16617.

[6] Levi, M. D. et al., Condens. Matter Phys. 2002, 5, 329–362.

Figure 1
A Recurrent Neural Network Model for Battery Capacity Fade Curve Prediction Using Early Life Data
Authors: Saxena Saurabh , Ward Logan , Kubal Joseph , Kim Hong-Keun , Lu Wenquan , Babinec Susan , Paulson Noah
Published: July 2021

Batteries are often considered the most performance and reliability-limiting component of any electronic and electrical assembly. Thus their degradation trend characterization through extensive testing and development of life prediction algorithms using testing data have been at the forefront of battery research. However, battery testing is also time-consuming, and it can take at least few months, even years, to test a battery for cycle life performance under normal operating conditions. Hence, there is a need to develop tools for battery life and degradation trend prediction using limited cycle data. Early life prediction tools can facilitate battery qualification, timely replacement of batteries in critical applications, and even the secondary use market. In this study, we present a recurrent neural network-linear network model to predict the entire battery capacity fade curve using less than 100 cycles of data (~ 1 month of testing). The discharge voltage-capacity curves have been used as input to the model. Our approach is also able to predict the rollover point (knee point) in the capacity fade curve of the battery, which indicates the onset of increased capacity fade rate. We use the publicly available MIT dataset to show the validity of the approach and extend the previous work from Severson et al. [1] on the end-of-life prediction to the entire capacity fade trend prediction. The recurrent neural network can capture the sequential changes in discharge voltage-capacity curves with cycles and provide flexibility in terms of the input data size.

References

[1] Kristen A Severson, Peter M Attia, Norman Jin, Nicholas Perkins, Benben Jiang, Zi Yang, Michael H Chen, Muratahan Aykol, Patrick K Herring, Dimitrios Fraggedakis, Martin Z Bazant, Stephen J Harris, William C Chueh, and Richard D Braatz, “Data-driven prediction of battery cycle life before capacity degradation,” Nature Energy, volume 4, pages 383–391(2019).
Sensing and Catalysis Using Functionalized Oxoporphyrinogens
Authors: Hill Jonathan P. , Chahal Mandeep , Payne Daniel
Published: July 2021

Simple oxoporphyrinogen (OxP) derivatives are excellent colorimetric sensors for a variety of analytes including anions, acidity and enantiomeric excess. More recently, this family of compounds has grown to include rim-functionalized compounds, which also exhibit colorimetric properties. In this work, we have prepared differently rim-functionalized OxPs and we will present their properties with respect to sensing, including selective anion binding, ion pair sensing and

coupled sensing of other important polluting species. The sensing properties of OxPs rely on intermolecular hydrogen bonding interactions which, in turn, imply their possible applications in organocatalysis. These properties will be described with an emphasis on the identity of macrocyclic substituents, and how catalytic activity of the OxP macrocycles is established. Structural aspects of OxPs influencing their sensing and organocatalytic activities will be discussed.
Porphyrin-Hexabenzocoronene-Conjugates and Fullerenes
Authors: Jux Norbert , Lungerich Dominik , Hoelzel Helen , Ruppel Michael , Martin Max
Published: July 2021

We will present architectures based on porphyrins and hexaarylbenzenes/ hexabenzocoronenes and fullerene C60. Special emphasis lies on crystal packing phenomena.

We report on the synthesis, characterization, and properties of some of these novel systems.[1-4]

References

[1] D. Lungerich, J. F. Hitzenberger, M. Marcia, F. Hampel, T. Drewello, N. Jux, Angew. Chem. Int. Ed..
2014,
53, 12231-12235.

[2] D. Lungerich, J. F. Hitzenberger, W. Donaubauer, T. Drewello, N. Jux, Chem. Eur. J.
2016, 22, 16755-16759.

[3] M. M. Martin, D. Lungerich, P. Haines, F. Hampel, N. Jux, Angew. Chem. Int. Ed.
2019, 59; 8932-8937.

[4] M. M. Martin, D. Lungerich, F. Hampel, J. Langer, T. K. Ronson, N. Jux, Chem. Eur. J.
2019; doi.org/10.1002/chem.201904005

Figure 1
Polymerization of Self-Assembled Tetraazaporphyrins
Authors: Eichhorn S. Holger , Tahir M Nazir , Abdulhamied Elmahdy , Selivanova Maria , Rondeau-Gagné Simon
Published: July 2021

Polymerization of self-assembled supramolecular structures considerably increases their often limiting thermal and chemical stability, which widens their potential application in commercial products. Particularly interesting for self-assembled materials is the topochemical polymerization of diacetylenes to polydiacetylenes because it can be initiated photochemically and thermally without the need for additives, it proceeds with minimal structural changes, and it generates new functionality since polydiacetylene is a 1-dimensional organic semiconductor and absorbs visible light. Polydiacetylenes have been generated in single crystals, gel phases, thin films, and membranes but their formation in mesophases, such as liquid crystals, has been surprisingly little studied although higher ordered mesophases should support the topochemical polymerization of diacetylenes (1,3-butadiyne groups) and may give access to large domains of uniformly aligned materials.

Presented here are tetraazaporphyrins that contain eight alkyl chains with diacetylene groups to probe their mesomorphism and conversion into multifunctional polydiacetylene materials. While incorporation of diacetylene groups supports columnar mesomorphism, successful photopolymerization required the presence of directing amide groups that suppressed columnar in favour of nematic mesomorphism. Still, polymerization of the nematic mesophase generated a soluble nematic polydiacetylene of significantly higher molecular weight (Mn = 77 kDa or 25 monomer units by GPC) than what has been obtained in gel phases of related compounds. Formation of polydiacetylene was confirmed by Raman spectroscopy and its nematic structure was verified by UV-vis spectroscopy, polarized optical microscopy, and X-ray diffraction. Both, its nematic structure and the incorporation of eight side-chains per discotic unit provide the polydiacetylene with sufficient solubility for casting thin films on substrates. AFM studies of films casted onto silicon wafers revealed a grid-like structure of connected nanofibers.

Tahir et al. Langmuir 2019, 35, 15158
N-Confused Metallocorroles: Synthesis, Redox Properties, and Catalytic Activities
Authors: Ishida Masatoshi , Furuta Hiroyuki
Published: July 2021

Corrole is known as a contracted tetrapyrrolic macrocycle bearing an α,α'-linked bipyrrole moiety. Using a unique trianionic N4 donor environment at the inner core, various high-valent metal species have been examined for potential catalytic applications. To seek new reactivity of metallocorroles, we have previously designed and synthesized a specific carbacorrole ligand, namely N-confused/N-linked corrole analogs.[1] The former analog contains an inverted pyrrole moiety connected at the α and β’-linking positions, and the latter has a peculiar linkage between the pyrrole α-position and the pyrrolic nitrogen site. The distinct [NNNC] coordination environment of these carbacorroles stabilizes unique organometallic species such as a copper(III).[2]

In this work, we synthesized novel cobalt complexes with a benzo-fused corrole analog (i.e., benzonorrole). The electronic structure of the resulting complex is highly dependent on the number of axial pyridine ligands. The bis-pyridine adduct complex can be regarded as a diamagnetic Co(III) species. Removal of an axial pyridine ring from the corresponding complex yielded the oxygenated product at the inner carbon site immediately. Unlike the bis-pyridine adduct, the mono-pyridine cobalt complex is a singlet Co(II) ligand radical at the ground state as inferred from various spectroscopic means and DFT calculations. Due to the intrinsic redox-noninnnocent character, the cobalt(II) radical complex exhibits facile reduction nature. On this basis, we finally applied for catalytic hydrogen evolution reaction with these cobalt complexes.

[1] Fujino, K.; Hirata, Y.; Kawabe, Y.; Morimoto, T.; Srinivasan, A.; Toganoh, M.; Miseki, Y.; Kudo, A.; Furuta, H. Angew. Chem. Int. Ed.
2011, 50, 6855-6859; Toganoh, M.; Kawabe, Y.; Uno, H.; Furuta, H. Angew. Chem. Int. Ed.
2012, 51, 8753-8756.

[2] Maurya, Y.; Noda, K.; Yamasumi, K.; Mori, S.; Uchiyama, T.; Kamitani, K.; Hirai, T.; Ninomiya, K.; Nishibori, M.; Hori, Y.; Shiota, Y.; Yoshizawa, K.; Ishida, M.; Furuta, H. J. Am. Chem. Soc. 2018, 140, 6883-6892.
Synergistic NO Coupling By Heme and Lewis Acid
Authors: Khade Rahul , Zhang Yong
Published: July 2021

Bacterial NO reductases utilize a heme-nonheme active site to couple two NO to form N2O, an important step of the global N cycle. But the N-N coupling mechanism is still under active debates. Recent experimental work shows that Lewis acid such as BF3 coordination to the nitrosyl O-atom in monoheme-NO activates it towards N–N coupling to generate N2O. Since the parent complex without BF3 is unreactive, DFT calculations were used to understand some important features of this new reaction. Results show that BF3 coordination to (por)Fe(NO) significantly weakens the Fe-N and N-O bond and makes the nitrosyl N possess radical feature, both of which renders it susceptible for external NO attack. The nitroxyl character in (por)Fe(NO•BF3) and the associated experimental NO vibrational frequency decrease were reproduced computationally. As found in the experiment, the (por)Fe(NO) and NO reaction was calculated to be unfavorable, but the BF3 coordination makes the reaction thermodynamically favorable. Charge analysis shows that without Lewis acid, both NO moieties in (por)Fe(ONNO) are negatively charged and thus repulsive and unfavorable for NO coupling. However, with the Lewis acid, the distal NO becomes positively charged and now has attraction with the negatively charged proximal NO to favor coupling. Computational results also show that BF3 alone cannot induce NO coupling, which was proved experimentally. So, these results for the first time clearly show the critical synergistic effectof both iron porphyrin and Lewis acid on NO coupling, which may help understand the biological NOR mechanism in systems where both heme and nearby Lewis acid are available. More recent experimental work shows that this reaction is not limited to Fe and can occur with Co. DFT calculations support retention of the CoII oxidation state for the experimentally observed adduct (OEP)CoII(NO•BF3), the presumed hyponitrite intermediate (Por•+)CoII(ONNO•BF3), and the porphyrin π-radical cation by-product, which likely occurs at the hyponitrite stage. In contrast, the Fe analogue undergoes a ferrous-to-ferric oxidation state conversion during this reaction. Overall, these results support key reaction features in recent experiments and provide important theoretical insights into the origin of these novel experimental reactions and features.
Vitamin B12 – Bioinspiration for Catalysis
Authors: Gryko Dorota
Published: July 2021

Nature constructs and decomposes complex molecules with the help of enzymes and light as the ultimate energy source. However, despite enzyme’s fundamental benefits, their industrial application can be limited by their availability, instability towards certain reaction conditions, cost, scale, lack of suitable enzyme etc. A complementary approach to sustainable methodologies relies on the formation or cleavage of chemical bonds using bioinspired methods (methods imitating the efficient and elegant designs of biology) and recruiting light, the most abundant free energy source.

Vitamin B12 - a cofactor of many enzymes seems inspirational.[1,2] This type of catalysis has been successfully translated into the laboratory and used in a small collection of reactions.[2, 3] The advantage of using vitamin B12 as a catalyst lays in the complete stability of the central cobalt ion and by the definition it is nontoxic. It has also been well documented that the reaction mechanism usually follows a radical pathway, bringing a new dimension to this already interesting field.

Along this line, we have developed new vitamin B12-catalyzed reactions involving reduction of Co(III) to Co(I) or Co(II) and subsequent reactions with electrophiles or radicals. Under light irradiation vitamin B12 derivative unusually catalyzes a new olefinic sp2 C-H alkylation reaction, with diazo reagents as a carbene source, instead of the expected cyclopropanation, acylation of activated olefins. Light-induced vitamin B12-catalyzed methods are also suitable for C-O bond cleavage. These key findings emphasize the unique feature of vitamin B12 as a catalyst to achieve something unachievable with other methodologies or to find a greener approach.

[1] Banerjee, R. Chemistry and Biochemistry of B12, John Wiley & Sons, Inc, 1999; [2] K. ó Proinsias, M. Giedyk, D. Gryko, Chem. Soc. Rev.
2013, 42, 6605-6619. [3] Giedyk, M.; Fedosov, S.; Gryko, D. Chem.
Commun.
2014, 50, 4674-4676.

Figure 1
Decelerating Charge Recombination Using Fluorinated Porphyrins in N,N-Bis(3,4,5-trimethoxyphenyl)Aniline-Aluminum(III)Porphyrin-Fullerene Reaction Center Models
Authors: Holzer Noah
Published: July 2021

In supramolecular reaction center models, the lifetime of the charge-separated state depends on many factors. However, little attention has been paid to the redox potential of the species that lie between the donor and acceptor in the final charge separated state. Here, we report on a series of self-assembled aluminum porphyrin-based triads that provide a unique opportunity to study the influence of the porphyrin redox potential independently of other factors. The triads, BTMPA-AlPor-C60, were constructed by linking the fullerene (C60) and bis(3,4,5-trimethoxyphenyl)aniline (BTMPA) to the aluminum(III) porphyrin. The redox potentials of aluminum(III) tetraphenylporphyrin (AlPor) are tuned by substitution of phenyl, 3,4,5-trifluorophenyl, or 2,3,4,5,6-pentafluorophenyl groups in its meso positions. The C60 and BTMPA units are bound axially to opposite faces of the porphyrin plane via covalent and coordination bonds, respectively. Excitation of all of the triads results in sequential electron transfer that generates the identical final charge separated state, BTMPA•+-AlPor-C60•-, which lies energetically 1.50 eV above the ground state. Despite the fact that the radical pair is identical in all of the triads, the lifetime of the radical pair was found to be very different in each of the different systems, that is, 1240, 740 and 56 ns for the pentafluorophenyl, trifluorophenyl, and phenyl substituted systems, respectively. These results imply that the charge recombination is an activated process that depends on the midpoint potential of the central aluminum(III) porphyrin.
Molecular Co and Fe Catalysts for the Electrochemical and Photoelectrochemical CO2 Reduction with 2, 4, 6 and 8 Electrons
Authors: Robert Marc
Published: July 2021

Reduction of carbon dioxide has as main objective the production of useful organic compounds and fuels - renewable fuels - in which solar energy would be stored. Molecular catalysts can be employed to reach this goal. One route consists in first converting sunlight energy into electricity that could be further used to reduce CO2 electrochemically. Another approach is to directly use the visible photons and photo-stimulate the electrochemical reduction of the gas in the presence of an appropriate light absorbing material. Molecular catalysts may provide excellent selectivity. Hybrid systems in which a robust molecular catalyst is associated to a conductive or a semi-conductive support may combine the advantages of both homogeneous and heterogeneous catalysis.

Using Co and Fe bio-inspired complexes (porphyrins, phthalocyanines and quaterpyridines), our recent results for CO, HCOOH, CH3OH and CH4 production at molecular cathodes [1-5] and photocathodes [6-8] will be discussed. We will illustrate the synergy between electrochemical and photochemical approaches and the rich potential of molecular catalysts to generate fuels from CO2 used as a renewable feedstock.

References: [1] Wang, L. Chen, T-C. Lau, M. Robert, Angew. Chem. Int. Ed. 2018, 57, 7769-7773. [2] Ren, D. Joulie, D. Salvatore, K. Torbensen, M. Wang, M. Robert, C. Berlinguette, Science 2019, 365, 367-369. [3] Wang,K. Torbensen, D. Salvatore, S. Ren, D. Joulie, F. Dumoulin, D. Mendoza, B. Lassalle-Kaiser, U. Işci, C. Berlinguette, M. Robert, Nat. Commun. 2019, 10:3602. [4] Boutin, M. Wang, J. C. Lin, M. Mesnage, D. Mendoza, B. Lassalle-Kaiser, C. Hahn, T. F. Jaramillo, M. Robert, Angew. Chem. Int. Ed. 2019, 58, 16172-16176. [5] Azcarte, C. Costentin, M. Robert, J.-M. Savéant, J. Am. Chem. Soc. 2016, 138, 16639-16644. [6] Guo, C. Cometto, G. Chen, L. Chen, B. Ma, H. Fan, T. Groizard, W-L. Man,S-M. Yiu, K-C. Lau, T-C. Lau, M. Robert, Nat. Catal. 2019, 2, 801-808. [7] Ma, G. Chen, C. Fave, L. Chen, R. Kuriki, K. Maeda, O. Ishitani, T-C. Lau, J. Bonin, M. Robert, J. Am. Chem. Soc. 2020, 142, 13, 6188-6195. [8] B. Pati, E. Boutin, R. Wang, S. Diring, S. Jobic, N. Barreau, F. Odobel, M. Robert, Nat. Commun. 2020, 11:3499.
Highly Efficient (>15%) Organic Solar Cells Based on Porphyrins
Authors: Cuesta Virginia , de la Cruz Pilar , Sharma Ganesh D , Langa Fernando
Published: July 2021

The optical and electrochemical properties of porphyrins can be tailored by changing the central metal and functionalization of the periphery, being excellent candidates as donors for Organic Solar Cells (OSCs). In the early years, the PCE values of OSCs based on porphyrins were very low, but by structural modifications, we achieve efficiencies in the range of 15%. In this presentation, I´ll show our recent work in design, synthesis and application of A−π−D−π−A and D−π−A−π−D porphyrin-based small molecules for highly efficient OSCs.

References

V. Cuesta, M. Vartanian, P. d. l. Cruz, R. Singhal, G. D. Sharma and F. Langa, J. Mater. Chem. A, 2017,
5, 1057-1065.

S. Arrechea, A. Aljarilla, P. de la Cruz, M. K. Singh, G. D. Sharma, F. Langa. J. Mater. Chem. C,
2017, 5, 4742.

M. Vartanian, R. Singhal, P. de la Cruz, S. Biswas, G. D. Sharma and F. Langa, ACS Appl. Energy Mater.
2018, 1, 1304.

M. Vartanian, P. de la Cruz, F. Langa, S. Biswas, G. D. Sharma. Nanoscale,
2018, 10, 12100-12018.

M. Vartanian, R. Singhal, P. de la Cruz, G. D. Sharma, F. Langa, Chem. Commun, 2018, 54,14144-14147.

V. Cuesta, R. Singhal, P. de la Cruz, G. D. Sharma, F. Langa, ACS Mater. Interfaces, 2019, 11, 7216-7225.

Cuesta, R. Singhal, P. de la Cruz, G. D. Sharma, F.Langa ChemSusChem
2020 DOI: 10.1002/cssc.202002664.

Figure 1
Electron-Triggered Metamorphism in Porphyrin-Based Self-Assembled Supramolecular Polymers
Authors: Bucher Christophe , Chowdhury Shagor , Kahlfuss Christophe , Nassar Youssef , Al Shehimy Shaymaa , Dumont Elise , Demets Grégoire J. F. , saint-Aman Eric , Frath Denis , Chevallier Floris
Published: July 2021

Stimuli-responsive self-assembled molecular materials are currently subject to intense research activity. This growing interest stems largely from the myriad of exciting applications envisioned for dynamic supramolecular assemblies, also known as dynamers, in materials science, sensing, catalysis and electronics. Enormous technologic interests are for instance at stake in being able to devise molecular objects that could respond to external stimuli by changes in structure and function. These particular properties can lead to applications in various domains as (i) in molecular electronics, (ii) in analytic science, with switchable hosts allowing the controlled binding/release of pollutants or drugs, (iii) in materials science with the development of adaptive supramolecular polymers. Our group has been focusing over the past few years on the development of tailor-made redox-controllable molecular and supramolecular systems involving electrogenerated pi-radicals as key responsive and/or assembling elements [1-3]. In this lecture, we will focus on the physico-chemical properties of a series of porphyrin-based molecular tectons whose self-assembly can be controlled with optical or electrical stimulus. The dynamic properties of these stimuli-responsive molecular architectures and molecular materials will mainly be discussed on the basis of electrochemical, spectroelectrochemical and ESR experiments supported by quantum chemical calculations [4-7].

References

[1] C. Kahlfuss, E. Saint-Aman, C. Bucher (2016). Redox-controlled intramolecular motions triggered by π-dimerization and πmerization processes In T. Nishinaga (Ed.), Organic Redox Systems: Synthesis, Properties, and Applications (pp. 39). New-York: John Wiley and sons.

[2] H. D. Correia, S. Chowdhury, A. P. Ramos, L. Guy, G. J.-F. Demets, C. Bucher, Polymer International 68, 572 (2019).

[3] G. Brunet, E. A. Suturina, G. P. C. George, J. S. Ovens, C. Bucher, M. Murugesu, Chemistry - A European Journal, DOI: 10.1002/chem.202003073 (2020).

[4] S. Chowdhury, Y. Nassar, L. Guy, D. Frath, F. Chevallier, E. Dumont, A. P. Ramos, G. J.-F. Demets, C. Bucher, Electrochimica Acta 316, 79 (2019).

[5] C. Kahlfuss, S. Denis-Quanquin, N. Calin, E. Dumont, M. Garavelli, G. Royal, S. Cobo, E. Saint-Aman, C. Bucher, Journal of the American Chemical Society 138, 15234−15242 (2016).

[6] C. Kahlfuss, T. Gibaud, S. Denis-Quanquin, S. Chowdhury, G. Royal, F. Chevallier, E. Saint-Aman, C. Bucher, Chemistry - A European Journal 24, 13009 (2018).

[7] C. Kahlfuss, R. Gruber, E. Dumont, G. Royal, F. Chevallier, E. Saint-Aman, C. Bucher, Chemistry - A European Journal 25, 1573 (2019).
Tuning Redox Hopping Charge-Transport in Metal−Organic Frameworks
Authors: Deria Pravas , Maindan Karan , Li Xinlin
Published: July 2021

Metal−organic frameworks (MOFs) define high surface area molecular compositions for electrochemical and photoelectrochemical energy conversion and storage. For these, the electrode-injected or photoinduced charges need to be delivered to catalytic centers (or be collected at the external electrode). Understanding and improving the charge-transport processes within the redox-active MOFs are important. Here, we discuss some key tools to control the redox-hopping process in a series of hydrolytically robust topologically different Zr(IV)-MOFs made of tetrakis(4-carboxyphenyl)porphyrinato iron(III), TCPP(FeIII). Topological variation offers fixed but different center-to-center (Fe-Fe) distances to define the hopping rate. Furthermore, we also find that axial coordination at the Fe-center can alter its spin-state to impact the TCPP(FeIII/II) -centered reorganization energy involved in this self-exchange process. Interestingly, the ability to attain a complete hexa-coordinated TCPP(Fe) is spatially demanding and determined by the pore size. The improved hopping rate may have a significant impact on the catalytic performance.
Electronic Structure, Bonding, and Stability of Boron Subphthalocyanine Halides and Pseudohalides
Authors: Hildebrand Mariana , Holst Devon , Bender Timothy P , Kronik Leeor
Published: July 2021

Halides and pseudohalides of boron subphthalocyanine (BsubPc) are promising candidates for efficient yet stable organic photovoltaics. Here, we consider the electronic structure of such molecules using density functional theory (DFT). Based on the calculations, we find that the tetrameric boron bond is stabilized by an inductive effect at the axial substituent and by conjugative effects across the ring system. We further find that stability is dictated mostly by the axial moiety, whereas peripheral substitution dictates the position of frontier orbitals, thereby allowing for separate optimization of these two important properties.
STM Investigation of Y[C6s-Pc]2 and Y[C4o-Pc]2 Complexes at the Solution/Solid Interface: Substrate Effects, Sub-Molecular Resolution, and Covalently Saturated Sulfur
Authors: Hipps K. W. , Mazur Ursula
Published: July 2021

Substituents present on a molecule are known to significantly control the assembly, adsorption, and orientation behavior on solid surfaces. Using scanning tunneling microscopy (STM), self-assembly of the Y[C6S-Pc]2and Y[C4O-Pc]2 double-decker complexes were investigated at a solution-solid interface. At concentrations above 1 µM, Y[C6S-Pc]2 formed well-defined monolayers with low defect density on highly oriented pyrolytic graphite (HOPG). On Au(111), on the other hand, it formed dense groups of small islands with some isolated molecules. There was a clear preference for multiples of 15 degrees between the orientations of the islands. A clear visualization of the Y[C6S-Pc]2 inner molecular structure including the sulfur atoms was achieved. At concentrations below 1 µM, stable isolated single molecules were observed only on Au(111), not on HOPG. The thiol linked side chains favor strong adsorption on Au(111) surface, with isolated single molecules being easily visualized and stable over several image scans. On both HOPG and Au(111) isolated molecules of Y[C4O-Pc]2 are never observed, Even at very low solution concentrations small rafts of molecules on an otherwise open substrate surfaces are observed. On HOPG the structure of the Y[C4O-Pc]2 monolayer is complex with both an open and filled cubic structure occurring as a mixed structure. We suggest that core moieties with peripheral S-linked alkanes may generally be particularly strong adsorbates on gold. Density functional calculations suggest that the S-linked alkane substituent system may be as much as 1 eV more stable on Au than a similar O-linked system. This work demonstrates the important role of molecule-substrate interactions, bias voltage, tunneling current, and STM tip on controlling and stabilizing molecular assembly.
Defect and Structural Evolution Under High-Energy Ion Irradiation Informs Battery Materials Design for Extreme Environments
Authors: Rahman Muhammad Mominur , Chen Wei-Ying , Li Meimei , Bai Xian-Ming , Lin Feng
Published: July 2021

Defect and structural evolution can have a broad influence on battery materials ranging from electrochemistry to batteries for extreme environments.1–3 In this presentation, the fundamental interplay of defect and structural evolution promoted by high-energy ion irradiation in layered oxide cathodes are discussed. Li and Na layered oxides are subjected to Kr ion irradiation (1 MeV) at various fluences and the transformations of the materials are studied in situ. Our study shows that Li layered oxides are more structurally stable under irradiation than Na layered oxides. The better structural stability of Li layered oxides can be explained in terms of the facile formation of cationic antisite defects because of the smaller size difference between Li and the transition metals. Moreover, a mathematical model is presented to quantitatively probe the defect evolution in these materials under irradiation. Our model shows that the defect clusters induced by ion irradiation preferentially align along the Na/Li diffusion channels in the materials. This study presents critical information for the design of battery materials for extreme environments where materials damage due to irradiation can be significant. Fundamental defect evolution in layered oxide cathodes is also unraveled.1

Acknowledgement

This work is primarily supported by The Thomas F. and Kate Miller Jeffress Memorial Trust, Bank of America, Trustee, and the Jeffress Trust Awards Program in Interdisciplinary Research. F.L. and X.-M.B. also acknowledge their startup funds at Virginia Tech. The Na cathode was developed based on a project funded by the National Science Foundation (No. CBET-1912885). The Li cathode was developed based upon work supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Award Number: DE-EE0008444. The irradiation work at the IVEM User Facility at Argonne National Laboratory was supported by the U.S. Department of Energy, Office of Nuclear Energy under DOE Idaho Operations Office Contract DE-AC07-051D14517 as part of a Nuclear Science User Facilities experiment. X.-M.B. acknowledges the high-performance computing facilities at Virginia Tech’s Advanced Research Computing.

Reference

M. M. Rahman, W.-Y. Chen, L. Mu, Z. Xu, Z. Xiao, M. Li, X.-M. Bai, and F. Lin, Nat. Commun., 11, 4548 (2020).

Z. Xu, D. Hou, D. Kautz, W. Liu, R. Xu, X. Xiao, and F. Lin, Adv. Mater., 32, 2003417 (2020).

M. M. Rahman, J. Mao, W. H. Kan, C.-J. Sun, L. Li, Y. Zhang, M. Avdeev, X.-W. Du, and F. Lin, ACS Mater. Lett., 1, 573–581 (2019).