bluuebunny/crossref_metadata_2025 huggingface dataset:
Soft Variable Area Energy Harvester
Authors: Vallem Veenasri , Roosa Erin , Ledinh Tyler , Dickey Michael D
Published: July 2021

Capacitors are great tools to store electrostatic energy and can discharge current almost instantly when needed. Thus, they are widely used in electrical circuits and have become a crucial part of everyday life. Besides, variable capacitors are a vital component of electrostatic energy harvesters that can harvest mechanical energy. However, traditional rigid capacitors exhibit low capacitance due to a thick dielectric layer in between the electrodes limiting the charge storing capacity. Due to their rigid nature, harvesting mechanical energy by varying capacitance is limited to sliding or oscillating the electrodes up and down in a systematic way. Thus, they cannot convert all kinds of mechanical energy into electricity constraining the conversion efficiency. Here we create soft electrical double layer capacitors, which innately offer higher capacitance due to the small distance between the charged layers. Being deformable in nature, they can convert all kinds of mechanical input (slide, stretch, squish, twist, bend) into electrical energy. These devices generate around 0.23 mW m-2 by harnessing energy from mechanical motion without the need for an external power source unlike the traditional electrostatic energy harvesters. We have characterized the behavior of these devices as a function of several parameters including material properties and physical deformation. The devices behave as expected and the response of the devices to deformation match a physics-based model. The soft device generates an electrical signal when deformed, which may be useful for oceanic energy harvesting as well as wind energy harvesting. Besides, these devices can harvest human motion thereby find applications in wearable electronics, healthcare systems like rehabilitation and prosthetics.
Design of 3D Printed Batteries with Printable Water-in-Salt Gel Polymer Electrolyte
Authors: Yen Dean , Lin Cheng-Hung , Chen-Wiegart Yu-chen Karen Karen
Published: July 2021

3D printing, also known as additive manufacturing (AM), has emerged as a promising strategy to design and fabricate future energy storage devices. The benefits of 3D printed batteries include versatile, adaptable shape and geometry, enhanced performance with new architectural design, and the ability to integrate printing power sources with other 3D printable devices. Although significant progress has been reported, current 3D printed batteries design still presents several limitations. The printed battery cells may use a solid electrolyte, which can only be operated at an elevated temperature, or use a conventional organic liquid electrolyte, which is toxic and flammable. The use of oxygen and moisture-sensitive electrolytes especially presents challenges for packing and sealing 3D printable batteries.

To overcome these challenges, this work incorporated the latest developments in aqueous batteries into a novel 3D printable battery that can be fabricated directly in an ambient environment that is also more environmentally friendly in nature. Specifically, a gel polymer electrolyte (GPE) with a water-in-salt (WIS) concept was introduced in our 3D printed batteries. The WIS concept, using a highly concentrated electrolyte, offers a larger operation voltage compared with conventional aqueous batteries, whereas the GPEs formulation enables the printability and easier packaging than liquid counterparts. By combining the advantages of both WIS and GPE, the resulting 3D printable batteries show promise for much more simplified processing conditions, as well as performance. The structural, (electro-)chemical, and morphological evolution of the printed batteries are being investigated by synchrotron X-ray techniques and electrochemical analysis. Overall, our research explores the possibility for an easier and more environmentally friendly way to build 3D printable, customizable batteries for future technologies.
(Invited) Ultrafast Pump-Probe and Single-Particle Photoluminescence Studies of Charge Carrier Recombination and Extraction Dynamics of the Caesium Lead Halide Perovskite Nanocrystals
Authors: Samanta Anunay
Published: July 2021

The lead halide perovskites have emerged in recent years as the most promising materials in photovoltaic and photonic applications.1,2 As utilization of the full potential of these materials in these applications requires a thorough understanding of the pathways through which the photo-generated charge carriers relax and the rate of their relaxation and capture by other substances prior to recombination, we have been investigating the dynamics of charge carrier recombination and extraction in a variety of caesium lead halide perovskite (CsPbX3) nanocrystals employing femtosecond pump-probe, fluorescence upconversion and single-particle fluorescence techniques. In this talk, some of our recent studies, which throw important insight on these topics, will be presented.3-8

References:

Green, M.A.; Ho-Baillie, A.; Snaith, H.J. Nature Photonics
2014, 8, 506.

Yakunin, S.; Protesescu, L.; Krieg, F.; Badnarchuk, M.I.; Nedelcu, G.; Humer, M.; Luca, G.D.; Fiebig, M.; Heiss, W.; Kovalenko, M.V. Nature Communications
2015
, 6, 8056.

Mondal, N; De, A.; Das, S.; Paul, S.; Samanta, A. Nanoscale
2019, 4, 9796.

Mondal, N; De, A.; Samanta, A. ACS Energy Letts.
2019, 4, 32.

Seth, S.; Ahmed, T.; Samanta, A. J. Phys. Chem. Lett.
2018, 9, 7007.

Mondal, N; De, A.; Samanta, A. J. Phys. Chem. Lett.
2018, 9, 3673.

Ahmed, T; Seth, S; Samanta, A. ACS Nano
2019, 13, 13537.

De, A.; Das, S.; Samanta, A. ACS Energy Letts.
2019, 4, 32.
(Invited) Surface Photovoltage Spectroscopy Observes Junctions and Carrier Separation in Gallium Nitride Nanowire Arrays for Overall Water-Splitting
Authors: Osterloh Frank , Doughty Rachel , Chowdhury Faqrul , Mi Zetian
Published: July 2021

Gallium nitride (GaN) nanowire arrays on silicon are able to drive the overall water-splitting reaction with up to 3.3% solar-to-hydrogen efficiency. Photochemical charge separation is key to the operation of these devices, but details are difficult to observe experimentally because of the number of components and interfaces. Here we use surface photovoltage spectroscopy (SPS) to study charge transfer in i- and n- and p-GaN nanowire arrays on n+-Si wafers in the presence and absence of Rh/Cr2O3 co-catalysts. The effect of the space charge layer and sub-bandgap defects on majority and minority carrier transport can be clearly observed and estimates of the built-in potential of the junctions can be made. Transient illumination of the p-GaN/n+-Si junction generates up to -1.4 V surface photovoltage by carrier separation along the GaN nanowire axis. This process is central to the overall water-splitting function of n+-Si/p-GaN/Rh/Cr2O3 nanowire array. These results improve our understanding of photochemical charge transfer and separation in group III-V semiconductor nanostructures for the conversion of solar energy into fuels.

Figure 1
(Invited) Charge Carrier Dynamics of in2Se3 Nanocubes and Plasmonic Composites Fabricated By Laser Ablation As Primary Processes of Solar Energy Conversion
Authors: Dhongade Siddhant , Katayama Tetsuro , Pankaj Koinkar , Maki Yutaro , Furube Akihiro
Published: July 2021

We report a simple method to prepare indium(III) selenide (In2Se3) nanocubes by means of laser ablation in aqueous medium. The morphological characterization revealed that the nanocubes have an average size of 70 nm and XRD and micro-Raman analysis revealed that there was no phase change upon laser ablation The detailed study on ultrafast charge carrier dynamis of In2Se3 nanocubes have been performed comparing with that of bulk In2Se3 before laser ablation treatment. The density increase in intermediate trap states upon laser ablation was clarified, in which carriers have a long lifetime near the conduction band [1]. Furthermore, by making hybrid structures using plasmonic gold nanoparticles and metal oxide semiconductors based on hydrothermal process and laser ablation in the liquid method, we could prolong carrier lifetime and enhance photocatalytic reactivity under visible light irradiation. Detailed charge transfer dynamics regarding the electron transfer time and energy relaxation across the nano-interfaces will be presented.

Reference

1. Siddhant Dhongade, Pallavi R. Mutadak, Amol B. Deore, Mahendra A. More, Akihiro Furube, and Pankaj Koinkar, ACS Appl. Nano Mater. 2020, 3, 9749−9758
Switchable Anode and Cathode Materials for Water Splitting Under Alkaline Conditions
Authors: O'Mullane Anthony Peter
Published: July 2021

The ability to store energy from intermittent renewable energy sources is a significant challenge that can be addressed by generating hydrogen as a storage medium via electrochemical water splitting. To ensure the production of hydrogen at scale, there is an urgent need to develop new cost-effective catalyst materials that are active yet stable. There has been a significant research effort in this area for both the hydrogen evolution reaction (HER) at the cathode and the more sluggish oxygen evolution reaction (OER) at the anode where the latter limits the overall efficiency of an electrolysis cell. In particular, transition metal based electrocatalysts containing chalcogenides (S and Se) or phosphorous have been extensively reported as bifunctional electrocatalysts for overall water splitting. However there remains the question as to whether the pristine material is truly bifunctional with regards to inherent activity for both the HER and the OER which has implications for their use in commercial electrolysers.

In this talk I will summarise our recent work on the concept of bifunctional electrodes for overall water splitting. The importance of catalyst characterization post reaction is demonstrated to elucidate the true nature of the active material that is responsible for electrocatalytic activity and how the surface chemistry and crystallinity of the catalyst changes. The implications of this in developing bifunctional catalysts for electrolysers integrated with intermittent energy sources that may be subject to rapid start up and shut down conditions is also discussed. Finally demonstration of electrocatalysts that can be switched between the OER and HER under an accelerated stress test without loss of activity is presented.
Electrosynthesis of π-Extended Porphyrins Via Reductive Decyanation
Authors: Osterloh William Ryan , Kumar Sandeep , Chaudhri Nivdeita , Fang Yuanyuan , Sankar Muniappan , Kadish Karl
Published: July 2021

The development of new electrochemically driven synthetic routes to obtain π-extended porphyrins, or new synthetic porphyrins in general, is highly desirable since electrosynthesis is often able to afford a clean conversion of reactants to products without a great deal of contamination. At the same time, electrosynthesis, when combined with classical electrochemical measurements, can often provide unique insights into the mechanism and intermediates involved in formation of the desired product. This is explored in the current work where a novel electrosynthetic method for generation of π-extended porphyrins and the corresponding reductive decyanation mechanism is described. The heterogenous anion induced electrosynthetic method is also compared to a homogenous chemical synthesis method to obtain the same products, using anion-induced electron transfer (AIET). The starting porphyrins are β,meso-fused malononitrile derivatives are represented as MTPP(MN)2 and the π-extended, di-fused products as MTPP(VCN)2, where TPP = the dianion of tetraphenylporphyrin, MN = malononitrile, VCN = vinyl cyanide and M = H2, NiII, CuII and ZnII. Structures of these porphyrins are shown in Chart 1. The easily synthesized π-extended porphyrins with two fused cyanobenzene (benzonitrile) rings are characterized by three facile and reversible one-electron ring-centered reductions in THF containing 0.1 M TBAP. There is also a fourth irreversible reduction at the edge of the solvent.

Figure 1
Modulation of Aromaticity and Properties of Porphyrins By Peripheral Heterole-Fused Structures
Authors: Nishimura Issei , Higashino Tomohiro , Imahori Hiroshi
Published: July 2021

Porphyrins are macrocyclic 18π aromatic molecules that have been actively studied in various fields owing to their intriguing properties for diverse applications. The introducing peripheral fused structures are quite effective for electronic perturbations and realizing red-shifted absorption spectra because of their expanded π-conjugated networks. In particular, the introduction of heteroles, i.e., five-membered π-conjugated molecules with main group elements, has attracted attention as heteroatom-embedded porphyrins. Because the properties of heterole derivatives can be modulated by main group elements and their oxidation states, we envisioned that the properties of fused porphyrins would also be modulated by heterole-fused structures. Herein, we report new synthetic strategies for heterole-fused porphyrins using [2+2+1] cyclization of bis(alkynyl)porphyrin, e.g., phosphole- and pyrrole-fused porphyrins. The oxidation state of the phosphorus atom had a clear influence on the aromatic character and the resultant electronic properties. In addition, the pyrrole-fused structure exhibited larger perturbation compared to the phosphole-fused structure. Therefore, we demonstrated the modulation of their aromaticity and physicochemical properties by control of main group elements and their oxidation states.
Beta-Substituent and Metal Effect on Their Structures and Electrochemical Properties
Authors: Hiroto Satoru
Published: July 2021

Three-dimensional π-conjugated molecules have received extensive attention in many chemical research areas due to their interesting structure and unique characteristics. In particular, twisted π-conjugated systems have been focused on for potential applications to solution processible organic materials. To date, numerous twisted organic molecules such as twistacenes have been synthesized. Under these situations, we found that oxidation of beta-amino substituted porphyrins provided highly twisted porphyrin dimers in excellent yield. Sequential use of amination and oxidation of 5,10,15,20-tetramesitylporphyrins afforded highly twisted porphyrin oligomers. The structures of the dimers proved dependent on substituents at porphyrin periphery. This time, we succeeded in the synthesis of beta-substituted porphyrin oligomers by using the oxidative dimerization protocol. Introduction of more bulky substituents at meso-positions on oxidation process provided the corresponding twisted porphyrin dimers with larger twisted angles. As a result, beta-substituents induced more distortion of porphyrin oligomers. In addition, electrochemical analysis revealed the distortion caused reduction of electronic communications between each porphyrin unit. We also found beta-methyl substituted porphyrin oligomer exhibited solvent-dependent and temperature dependent optical property. Theoretical calculations as well as electrochemical measurements suggested that conformational change by solvent and temperature caused change of absorption spectrum of the tetramer. Such conformational change dependent on solvent is quite rare for porphyrin oligomers and that should lead to novel stimuli-responsive porphyrin oligomers.

Secondly, we also investigated the central metal effect on the electrochemical properties and structures of the dimers. The central Ni(II) metal can be readily removed by treatment of concentrated sulfonic acid. Insertion of Zn(II) and Cu(II) metals induced planarization of porphyrin planes, resulting in smaller twisting angle of the corresponding dimers. In the case of the Cu(II) complex, the presence of magnetic interactions between two porphyrin units were revealed by temperature dependent magnetic susceptibility measurements. In this presentation, we will disclose the structural characterizations of these dimers and would like to show the relationship between electrochemical properties and the conformations of porphyrin dimers.

Figure 1
Progress in Boron Subnaphthalocyanines (BsubNcs) –Targeting Bay Position Halogenation and Avoiding It and Its Electrochemical Impact
Authors: Bender Timothy P , Holst Devon , Kronik Leeor , Hildebrand Mariana
Published: July 2021

For some time, our group has been focused on the molecular design, synthesis and application of derivatives of boron subphthalocyanines (BsubPcs) and subnaphthalocyanines (BsubNcs), which are compounds with a chelated central boron atom and an extensive p-conjugated macrocyclic ligand. Our focal point continues to be balanced between the basic and applied chemistry of the BsubPcs and BsubNcs, their physical properties (electrochemistry included) and their application as light emitting, light absorbing and electronic conducting materials in organic light emitting diodes (OLEDs) and organic photovoltaics (OPVs)/organic solar cells (OSCs) respectively; the basic electrochemical and photophysical properties being critical to these applications.

For this presentation, I will focus on our progress on the development of BsubNcs. In the past we have shown that BsubNcs end up being a mixed allowed composition based on bay-position halogenation that was formed randomly during the reaction of BCl3 with 2,3-dicyanonaphthalene at temperature on forming the BsubNcs. The random bay-position halogenation has been shown to be impactful in a positive way within OPV devices, negative within OLED devices and also has electrochemical variations. However given it is random halogenation, it is desirable to truly understand its impact systematically.

I will outline how the use of BBr3 for the formation of the BsubNcs impacts the outcome, also enables random bay-position halogenation and does enable the first example of the bay-position halogenated BsubNcs to be separable.

From a basic chemistry perspective, I will then highlight that we have progressed on blocking the random bay-position halogenation by developing a method to entirely avoid the bay-position halogenation. I will outline the approach and show the first basic characterization of non-bay-position halogenated BsubNc and the relative characteristics of the associated BsubNcs. Electrochemical comparison of the BsubNcs will also be outlined and also spectroelectrochemistry characterization.

We have also applied computational modelling to look at the relative impact of the random bay-position halogenation. We have found that the frequency of halogenation has a larger impact on the predicted HOMO/LUMO energy levels than does the random halogen positioning and will be discussed.

I will also outline our approach to accelerated development of BsubNcs whereby their molecular design and synthesis is first justified through a re-adopted computational model. I will show how we calibrate several levels of computational modelling relative to and against a firm set of experimental data. I will then move onto several examples of how we have developed BsubNcs for their application in organic electronic devices utilizing this method.

Figure 1
Mechanistic Studies on the Reactions between Cobalamins and the Biological Signaling Molecule Nitroxyl (HNO)
Authors: Brasch Nicola E , Polaczek Justyna , Cink Ruth B , Subedi Harishchandra , van Eldik Rudi
Published: July 2021

The N-hydroxysulphonamide Piloty’s acid, PhSO2NHOH, was first reported in the scientific literature over a century ago. N-hydroxysulphonamides have recently attracted considerable attention, due to their propensity to spontaneously decompose to cleanly release nitroxyl (HNO) upon deprotonation of the parent molecule. Like its well-established cousin nitric oxide (NO), HNO is a biological signaling molecule with a rich redox chemistry. Furthermore therapeutics that generate HNO in vivo show considerable promise in treating cardiovascular disease including congestive heart failure, through mechanisms unique to HNO. HNO reacts primarily with metal centres and thiols (protein thiol residues and small molecular weight thiols) in biological systems.

The cobalt-containing vitamin B12 macrocycle is a cofactor for numerous enzymes in humans and bacteria. Detailed mechanistic studies on the reactions of Piloty’s acid with all three oxidation states of vitamin B12 – Co(I), Co(II) and Co(III) – will be presented, and reveal a complex and rich coordination chemistry for this simple triatomic molecule.
Synthesis, Spectral and Electrochemical Studies of β-Trisubstituted Porphyrins and Monobenzoporphyrins
Authors: Bulbul Amir Sohel , Sankar Muniappan
Published: July 2021

Meso-Tetraarylporphyrins having electron-withdrawing substituents viz. nitro, formyl, acyl, or bromo groups is the key precursor to expand the chemistry of β-functionalized porphyrins.1 These β-functionalized porphyrins have been utilized in nonlinear optics, anion sensing, gas storage, photodynamic therapy (PDT), and dye-sensitized solar cells (DSSC).2 Modulating the degree of π-conjugation and introducing suitable donor-acceptor substituents at β-positions result red-shifted electronic spectral features, low HOMO-LUMO gap and high ground state dipole moment which are essentials for enhanced nonlinear optical behavior. Benzoporphyrin derivatives are currently under investigation as photosensitizers for PDT.3 Herein, we synthesized unsymmetrically functionalized trisubstituted porphyrins and monobenzoporphyrins in one step and characterized by various spectroscopic techniques viz. UV-vis, fluorescence, NMR, MALDI-TOF mass spectrometry and electrochemical studies.

The synthesized trisubstituted porphyrins and monobenzoporphyrins were significantly red-shifted as compared to their precursor porphyrins. Further, these porphyrins exhibited a large anodic shift in reduction and cathodic shift in oxidation potentials due to extended π-conjugation and electron-withdrawing β-substituents. In this presentation, we will present the facile synthesis, photophysical and intriguing electrochemical redox properties of π-extended porphyrins.

Figure 1. Molecular structures, absorption spectral profile and cyclic voltammograms of synthesized porphyrins.

References:

Moura, N. M. M. et al,
J. Porphyrins Phthalocyanines
15, 2011, 652-658.

(a) Senge, M. O. et al,
Eur. J. Org. Chem.
2011, 5797-5816. (b) Sankar, M. et al, Chem. Commun.
41, 2012, 6481-6483. (c) Kumar, R. et al,
Inorg. Chem., 53, 2014, 12706-12719. (d) Higashino, T. et al,
Dalton Trans.
44, 2015, 448-463. (e) Sankar, M. et al, ACS Appl. Energy Mater.
1, 2018, 2793-2801. (f) Dar, T. A. et al,
Green Chem.
21, 2019, 1757-1768.

(a) de-Torres, M. et al,
Chem. Commun.
51, 2015, 2855-2858. (b) Zhang, X. et al, ACS Nano
12, 2018, 4630-4640. (c) Grover, N. et al,
Inorg. Chem.
58, 2019, 2514-2522.

Figure 1
Facile Synthesis, Spectral and Electrochemical Properties and Catalytic Efficiencies of β-Octabromo Vanadyl Porphyrin
Authors: Prakash Ved , Maurya Mannar ram , Sankar Muniappan
Published: July 2021

Selective oxidation of olefins to epoxy compounds has always been an interesting area of research for chemists owing to their great importance in the production of highly valued commodity chemicals such as polyurethanes, unsaturated resins, glycols, surfactants, and other products. Further, oxidative bromination of thymol and other phenolic derivatives has industrial importance. Iron and manganese porphyrins have been widely utilized as effective homogeneous catalysts for such oxygenation reactions in the last few decades. The major drawbacks of homogeneous MTPP-based catalysts are the macrocyclic ring which is liable to oxidative self-destruction, aggregation of metalloporphyrins through π–π interactions, lower turnover frequency (TOF) and poor product selectivity. Notably, vanadyl porphyrins have gained significant interest as useful molecules with applications in the fields of therapeutics, catalysis and 3D supramolecular assemblies. Herein, we synthesized vanadyl complex of β-octabromo-meso-tetraphenylporphyrin (VOTPPBr8) by self-catalytic reaction of VOTPP in excellent yield ar room temperature under mild bromination conditions using KBr/H2O2 in presence of HClO4. Further, VOTPPBr8 was utilized as an efficient catalyst for the epoxidation and oxidative bromination reactions. In this presentation, we will present facile synthesis, spectral and electrochemical properties and catalytic efficiencies of VOTPP and VOTPPBr8 in detail.
Photochemical Reactivities and Photodynamic Effects of an Organorhodium Phthalocyanine
Authors: Murata Kei , Saibe Yuki , Misawa Ryuji , Ikeuchi Yoshiho , Ishii Kazuyuki
Published: July 2021

The light-triggered uncaging of bioactive molecules is attractive for a new type of photodynamic therapy (PDT) as it enables the tumor-selective cell attack in various mechanism of action. In particular, photochemical release of formaldehyde is promising as they exhibit cytotoxicity by the alkylation and crosslinking of biological tissues.[1] Meanwhile, methyl-cobalt porphyrinic compounds are known to give formaldehyde by the homolytic cleavage of a metal-carbon bond under visible light irradiation in the presence of molecular oxygen.[2] However, there has been no report on the photochemical formation of formaldehyde under irradiation of red light which shows high permeability toward biological tissues. In this study, the organometallic phthalocyanine complexes possessing a group 9 metal center were synthesized, and their photophysical properties, photochemical reactivities and photodynamic effects were investigated under red light irradiation.

Through the screening of reaction conditions, the methyl-rhodium phthalocyanine complex (1) was found to give formaldehyde by irradiation of pulsed laser of red light in the presence of oxygen. The laser-power dependency on the conversion rate indicated that the metal-carbon bond of 1 is activated through the stepwise, two-photon excitation. In order to realize the photochemical formation of formaldehyde in biological environment, 1 was encapsulated into a liposome of 1,2-Dipalmitoyl-sn-glycero-3-phosphorylcholine (DPPC). By irradiation of red light, the liposomal 1 released formaldehyde in water under air. Finally, the phototoxicity and cytotoxicity of liposomal 1 toward HeLa cells were investigated. The HeLa cells treated by liposomal 1 were successfully killed by light irradiation, indicating that 1 exhibits the photodynamic effect.

References

[1] Huang, H.; Hopkins, P. B. J. Am. Chem. Soc.
1993, 115, 9402-9408.

[2] Dolphin, D.; Johnson, A. W.; Rodrigo, R. J. Chem Soc.
1964, 3186-3193.
Host-Guest Chemistry of Porphyrins in Liquid Crystalline Macrocycles
Authors: Tanaka Kentaro
Published: July 2021

Structurally well-defined macrocyclic molecules have great potential to accommodate specific guest molecules in the hollow. Recently, we have reported a series of macrocycles which are composed of four carbazoles connected with four salphen ligands1, four dibenzothiophenes connected with four salen ligands2, or four diindrocarbazoles connected with four salphen ligands3 (MC1, MC2 and MC3, respectively). The macrocycles with appropriate peripheral alkyl chains and their tetranuclear metal complexes with square planar metal ions showed thermotropic columnar liquid crystalline properties1,2. These macrocycles stacked to form columns inside the fluid materials. Especially, the giant macrocycle MC3 contained a square hollow with a diagonal of 2.5 nm. This giant macrocycle has the largest inner cavity among known discrete shape-persistent macrocycles that exhibit thermotropic LC properties. The size and shape of the hollow structure make it interesting for molecular inclusion applications. For example, MC3 molecule can accommodate a tetrapyridylporphyrin inside the hollow to afford a planar conjugate, and the conjugate showed liquid crystalline behavior.

Reference:

[1] S. Kawano, Y. Ishida, and K. Tanaka, J. Am. Chem. Soc.
2015, 137, 2295.

[2] Kawano, S.; Hamazaki, T.; Suzuki, A.; Kurahashi, K.; Tanaka, K. Chem. Eur. J., 2016, 22, 15674-15683.

[3] Kawano, S.; Kato, M.; Somiya, S.; Nakayama, M.; Onoe, J.; Tanaka, K. Angew. Chem. Int. Ed.,
2018, 57, 167–171.

Figure 1
DFT Investigation of Porphyrin Aggregates
Authors: Sabuzi Federica , Stefanelli Manuela , Monti Donato , Conte Valeria , Galloni Pierluca
Published: July 2021

Owing the attractive potential applications of porphyrin assemblies in photocatalysis, sensors and material science, nowadays studies concerning porphyrin aggregation are largely diffused. These chromophores can organize in elaborated architectures by an assorted set of non-covalent interactions (i.e. π–π stacking, H-bonding, metal coordination, hydrophobic effect, and electrostatic forces) between the tetrapyrrolic macrocycles, mostly in J-or H-aggregated species, where the aromatic platforms are stacked side by side and face to face, respectively. UV-vis spectroscopy allows the identification of the porphyrin arrangement within the aggregates, through the modified spectral features of the porphyrin monomer following the interaction among the porphyrin units. Despite plenty of experimental investigations dealing with the self-organization of porphyrin both in solution and at the solid state, computational studies are still limited.

In this communication, a computational examination of the different porphyrin aggregation approaches will be presented, taking into account the amphiphilic [5-{4-(3-trimethylammonium)propyloxyphenyl}-10,15,20-triphenylporphyrin] chloride, whose aggregation behavior has been previously experimentally investigated. In particular, the definition of appropriate functionals to study and characterize porphyrin aggregates, to get more insights on the kind of the interactions responsible for the formation of the specific noncovalent systems (J-, H-, T- or cation-π aggregates) experimentally observed will be proposed.

Fig. 1. Optimized geometry of H-type (left) and cation-π (right) dimers of [5-{4-(3-trimethylammonium)propyloxyphenyl}-10,15,20-triphenylporphyrin] chloride in water, with WB97XD functional and 6-31G(d) basis set.

Figure 1
Using the Electrode Potential to Orient Single Molecules in Nanoscale Electrical Junctions and Determine Charge Transport Mechanism
Authors: Borguet Eric
Published: July 2021

Charge transport through and between molecules is central to important processes in nature. Studying the conductivity of single molecules can contribute to a better understanding of charge transport, and also help to develop building blocks of molecular electronics, light harvesting devices, etc. We measure the conductivity of molecules using the Scanning Tunneling Microscope break-junction (STM-BJ) method that utilizes repeatedly formed circuits where one or a few molecules are trapped between two electrodes, at least one of which has nanoscale dimensions. The statistical analysis of thousands of measurements yields the conductance of single molecules.

One particular interest is the role of the molecule-electrode contact and orientation in charge transport. In the simplest analysis this contact can present a substantial barrier to charge injection, which can have important consequences in devices such as dye sensitized semiconductor nanoparticle solar cells. Our most recent developments include controlling the orientation of the molecule in the junction using the electrode potential so that we can measure conductance along different molecular axes, accessing elements of the anisotropy of the molecular conductance tensor. Specifically, when the molecule is oriented flat, with the molecular plane parallel to the electrode surface, charge transport is measured perpendicular to the molecular plane. Furthermore, the electrode dependence of the molecular conductivity provides insight into the transport mechanism. This approach can be applied to molecules that do not have suitable molecular anchoring groups for traditional STM-BJ measurements, and allows us to determine the importance of anchoring groups in charge transport in molecular junctions.
Two-Dimensional Layered Materials for Electrochemical Energy Storage and Conversion
Authors: Wei Sichen , Fu Yu , Chang Chaoran , Liu Maomao , Li Huamin , Yao Fei
Published: July 2021

The fast development of modern technology requires matured energy storage and conversion devices to meet the demands of the ever-growing portable electronic and electric vehicle industries. As a result, electrochemical energy strategies including energy storage and electrocatalysis have attracted broad attention lately. Thanks to the fast development of nanoscience and nanotechnology, various structures and materials have been proposed with outstanding electrochemical performance. Two-dimensional layered materials including graphene, transition metal dichalcogenides, and MXene, etc., have demonstrated enormous potential as electrode materials for energy storage and conversion due to their robust properties of high electrical conductivity, large surface area, and superior chemical stability. In this talk, the electrochemical property of two-dimensional layered materials will be introduced. Advanced two-dimensional materials and their hybrids for the applications of electrochemical energy storage and electrocatalysis will be discussed.
High Aspect Ratio TiO2 Nanotube Layers Obtained in a Short Time
Authors: Alijani Mahnaz , Sopha Hanna , Ng Siow Woon , Macak Jan M.
Published: July 2021

In the last two decades, anodic TiO2 nanotube (TNT) layers have gained considerable attention for both their unique physical and chemical properties practical applications [1-3].

One of the key parameters that characterize TNT layers is the aspect ratio, which is the ratio between the TNT layer thickness and the nanotube diameter. In particular, TNT layers with a high aspect ratio (HAR) due to their 1D ordered structure, an exceptional morphology and a high surface area, have a great potential in different applications, such as filtration and micro-photo reactors [4,5]. In the last decade, ethylene glycol (EG)-based electrolytes containing small amounts of NH4F and H2O [6] were the most widely used electrolytes to produce high-aspect ratio TNT layers. However, using these electrolytes very long anodization times i.e., several hours or up to several days [7], are needed. Apparently, the synthesis of long and extremely robust HAR TNT layers in a relatively short time remains very challenging until now. Recently, it has been shown that the addition of lactic acid (LA) to EG-based electrolytes can shift the dielectric breakdown potential to significantly higher potentials due to the strong adsorption of lactic acid on TiO2 during the anodization [8]. Thus, considerably higher anodization potentials and increased electrolyte temperatures can be employed and HAR TNT layers can be obtained within less than one hour of anodization.

In this presentation we will demonstrate that HAR TNT layers can be obtained within short anodization times using an optimized anodization protocol. The key feature is the use of NH4F/H2O/EG electrolytes containing LA with optimized electrolyte [9].

Experimental details and some recent anodization results will be presented and discussed.

References:

[1] J.M. Macak et al., small. 2007, 300-304,3.

[2] J.M. Macak et al., Curr. Opin. Solid State Mater. 2007, 3-8,11.

[3] R. Poulomi, et al., Nanoscale. 2010, 45-59, 2.

[4] G. Cha, et al., Electrochim. Acta
2020, 302-310, 258.

[5] Z. Xuemei, et al., ACS Catalysis
2017, 3210-3235, 7.

[6] K. Lee et al., Chem. Rev.
2014, 9385-9454, 114.

[7] S.P. Albu et al., Phys. Status Solidi RRL.
2007 R65-R67, 1.

[8] S. So et al., J. Am. Chem. Soc.
2012, 11316-11318, 134.

[9] M. Alijani et al., Electrochim. Acta
2020, submitted.
Carbon Disuphide Mediated Synthesis of 1,3-Benzothiazole-2(3H)-Thione Toward Inhibiting for Biodegradable Zinc Bone Implant in Bodily Fluid
Authors: Eduok Ubong
Published: July 2021

Clinical problems associated with stress shielding and secondary surgery are mostly addressed by using biodegradable implant materials as effective alternatives in dentofacial orthopedics. These implants are normally installed in between tissues of a host to rehabilitate an impaired physical function while also mimicking a desired cellular characteristic without rejection toward improved quality of life. However, some of these implants are also susceptible to corrosion. In the present study, a corrosion inhibiting 1,3-Benzothiazole-2(3H)-thione (MBT) compound is synthesized and utilized in studying metallic bone implant corrosion in simulated bodily fluid. MBT was synthesized from a CS2 mediated synthesis mechanism involving a catalyzed reaction between aminophenyl disulfide with metal sulfide under N2 atmosphere (Figure 1 a). The MBT synthesis mechanism involved the formation of a C-S bond under relatively less reaction duration and milder thermal conditions, as an alternative route to organic thiols (Figure 1 b-c). The tendency of MBT toward zinc-surface adsorption and corrosion inhibition was investigated in bodily fluid. MBT acted as a corrosion inhibitor within this medium and this was consistent with molecular adsorption and formation of MBT films on the biodegradable zinc bone implant substrate. The MBT heterocyclic molecular structure may have been the greater edge toward Zn surface adsorption, hence corrosion inhibition. The extent of interfacial interactions between MBT and the Zn layer was also theoretically examined by molecular dynamic simulations. Zn implant corrosion resulted in chloride-induced pit with a predominantly cathodic kinetics in the presence of MBT. Since molecular structure is an important aspect of sustainable corrosion inhibition design, the study reflects a modern design for alleviating corrosion in zinc bone implant.

Keywords:

Biodegradable zinc bone implant;
2-mercaptobenzothiazole; CS2 mediated synthesis, Zinc corrosion; Corrosion inhibition.

Figure 1
Development of a Stimuli-Responsive Supramolecular Brush for Enhanced Post-CMP Cleaning
Authors: Linhart Abigail N , Keleher Jason J.
Published: July 2021

With the miniaturization of device features, slurry chemistries have become increasingly complex and therefore require enhancement of current cleaning processes. Copper (Cu) chemical mechanical planarization (CMP), a critical process step in the fabrication of high-performance microprocessors, utilizes nanoparticle abrasives (i.e. SiO2) and functional chemistry (i.e. complexing agents, inhibitors, and pH adjusters) during the polishing process which can lead to contaminants on the wafer surface. Currently, post-CMP cleaning processes use a standard polyvinyl alcohol (PVA) brush coupled with functional cleaning chemistry to remove these contaminants, including organic residue, particle contaminants, and excess ions. With stringent contaminant-free demands, it is crucial to develop cleaning consumable sets to meet these demands. This work focuses on the functionalization of PVA with supramolecular moieties to enhance the removal of nanoparticle and organic residue. Results have shown that the addition of supramolecular complexes to the PVA brush enhanced particle removal through hydrophobic/hydrophilic interactions at the brush/wafer interface. Additionally, this functionalized PVA brush shows increased adsorption of metal ions (specifically Cu2+) via inclusion complexes. Initial results have also shown that PVA containing pore forming additives have a photochemical response in which when irradiated with specific wavelengths of light the brush can be turned “on” or “off” based on chemical interactions at the brush/wafer interface.
(Invited) Reimaging the CMP Process Utilizing Photoactive Slurry Formulations
Authors: Keleher Jason J.
Published: July 2021

Chemical Mechanical Planarization (CMP) has emerged as a critical process step for achieving angstrom-level uniformity in advanced integrated circuit manufacturing and has ultimately led to the extension of Moore’s Law. Due to the emergence of these sub-7 nm technologies, next generation CMP slurry formulations have continued to increase in additive complexity to meet stringent device specifications. Currently, the most common processing condition to modulate removal rate is the use of mechanical parameters (i.e. downforce, flow rate, and platen speed). However, these parameters may manifest in increased defectivity (i.e. scratches and dishing/erosion) due to increased shear force/friction and chemical activity. This work focuses on the utilization of photo switching mechanisms to tune the slurry nanoparticle surface to enhance its electrophilicity and ultimately increase the rate of removal upon irradiation. More specifically, this presentation will discuss two modes of photo-switching to selectively modulate oxide removal rates. One mode exploits a photo-induced adsorption/desorption mechanism to alter the oxygen vacancy availability to provide an “off/on” switch for removal. While another mode utilizes a light induced ligand-metal charge transfer (LMCT) in which the particle is reduced and the functional additive is desorbed allowing for greater oxygen vacancies as well as less steric hinderance.
Engineered Ceria Slurries for Electronic Glass Substrate CMP Application
Authors: Kuan Chun_Lung , Zhou Renjie , Sherlock Jason , Hui_Bui Long
Published: July 2021

Glass substrates have gradually gained more attention as the media platters in hard disk drives (HDD) used in laptops, data centers, and cloud storage due to its advantageous properties. Particularly, advanced technologies like Heat Assisted Magnetic Recording (HAMR) in HDD and Through-Glass-Via (TGV) in 3D packaging applications all require the use of glass substrates with precisely controlled surface properties. Glass substrate’s advantages include lower weight, improved flatness, less flutter at high RPM’s and lower thermal expansion as compared to aluminum / NiP substrates. This lower expansion when exposed to heat makes it ideal for HAMR technology, which will be the key to creating hard disk drives with growing storage capacity. Chemical mechanical polishing (CMP) is a method to eliminate surface defects induced by grinding & lapping to meet final requirements of HAMR or TGV for glass substrates with surface finishes down to a few angstrom level or less. Key performance targets include removal rate, surface roughness, TTV, FSW, ceria residue / particle content (cleanability) on glass disks as well as recyclability. In this study, slurries for CMP are investigated utilizing engineered ultra-pure ceria particles which are known to have high material removal rate (MRR) on glass substrates. Various particle sizes, morphology, and chemical additives were evaluated. Results of systematic CMP tests including MRR, surface roughness, recyclability, and most importantly, ease of ceria residue removal from the glass substrate will be reported. Morphology of ceria particles was found to play a critical role in MRR. An optimized combination of ceria morphology and additive chemistries enables high MRR together with improved Ceria residue / cleanability performance.

Figure 1
Comparative Analysis of Chemical Mechanical Planarization Performance on Low-K Films
Authors: Johnson Cody Alan , Jebaraj Johnley Muthuraj Josiah Jebaraj Johnley , Brown Jay , Weymann Davis , Hunter Chase
Published: July 2021

Mirroring the pursuit for ever-shrinking feature size in memory architectures, the need for materials capable of preventing crosstalk between increasingly closer conducting lines has led to the replacement of silicon dioxide with alternative low-k materials. Within this subset of materials exist films with notably low dielectric constants; however, these materials present unique challenges for chemical mechanical planarization (CMP) in comparison to more traditional dielectrics, the least of which include undesirable scratching and erosion (e.g. dishing) of low-lying areas. Fortunately, some degree of tuning of film properties (e.g. modulus and hardness) is possible through various deposition methods and post treatment conditions, among others. In this study, two slurries containing common Ceria abrasives were utilized to examine a selection of films of varying properties and preparations across several CMP process conditions. A structural test vehicle having a series of feature sizes designed to feed CMP modeling was used for analysis. Static etch rate and material removal rate were measured using optical metrology. Dishing was quantified via atomic force microscopy (AFM), and scratching performance was analyzed via optical methods. Using the collected data, a mechanism for removal was proposed for each slurry.

Figure 1
Key Challenges Towards Scalability of Niobium Based Materials for Lithium-Ion Battery Technology
Authors: Santhanam Sumithra , Zhang Wanwei , Wu Jianshen , Pezin Joris , El Ouatani Loubna , Groombridge Alexander S.
Published: July 2021

Next generation high energy density and ultrafast charging lithium-ion battery technology requires fast charging anodes with high capacity, low volume expansion during cycling and moderate operating voltage. Li4Ti5O12 (LTO) is the only commercially available anode material that has the ability to safely fast charge in 5 mins with minimal expansion on intercalation of lithium-ions. However, it suffers from poor energy density and low capacity (<160 mAh/g) and poor electronic, ionic conductivities. Echion Technologies Ltd has developed “Mixed Niobium Oxide” -based anodes that it has commercialised to solve these issues, offering the ability to fast-charge in under 5 mins and maintain a long lifetime, with double the volumetric capacity of LTO materials (>640 mAh/cm3). In general, mixed niobium oxide materials [1,2] are intrinsically insulating and require improvement in electronic conductivity (by materials/particle engineering) for minimising impedance effects at the cell level. Material parameters (particle morphology, size distribution, microstructure), degradation mechanism and ageing of anodes play a vital role towards scalability of optimised materials for commercial devices and tailored applications. The different scalable synthesis techniques, processing parameters and their effect on material characteristics, electrochemical performances will be discussed in this talk. The critical challenges faced by industry towards scalability of materials and commercial devices will also be reviewed.

[1] Jian-Tao Han et.al., Chem. Mater., 23 (2011) 2027-2029.

[2] M. Bini et.al., Chemistry Select., 4, 19 (2019) 5656-5661.