bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Shear-Induced Fabrication of Multiple Parallel Gel Filaments Using Aqueous Two-Phase Separation
Authors: Kato Norihiro , Takayama Yuriko , Nagayoshi Keishu , Iimura Ken-ichi , Nasuno Eri 
Published: February 2020

Macroscopic structures of gel fibers have been prepared by control of the polymer solution properties and by design of the nozzle and flow path of the microfluidic device. In this research, we investigated a method to simultaneously fabricate hundreds to thousands of gel filaments simply by flowing the polymer solution inside the capillary without spinneret.
An aqueous two-phase separation (ATPS) can be induced by adjusting their concentration in certain combinations of two polymers. The respective polymer concentration in each phase can be determined from the phase diagram, whereas an assembly of heterogeneous polymers generate in each phase. Hydrodynamic properties of pre-gel solution can be controlled by inducing such heterogeneous polymer assemblies.
A co-axial flow double capillary was used to fabricate gel filaments, where an inner capillary (inner diameter 0.7 mm) was fixed at the insert position of an outer capillary. To induce ATPS, an ionic strength for the aqueous solution of sodium alginate (Alg) / polyethylene glycol (PEG) mixture was controlled by NaCl addition. The pre-gel Alg/PEG solution was flown as an inner flow of glass double capillaries, where a crosslinker solution (Ca2+ soln.) was flown as a sheath flow. The obtained gel was composed of multiple parallel gel filaments with a diameter of several micrometers, while a single gel without filament structure was obtained from the homogeneous solution without NaCl addition.
In aqueous solution, the Alg chain has a structure with few entanglements because of its rigidity. The rigid assembly of alginate is mainly caused by guluronic acid block, that is stabilized by diaxial linkages via intramolecular hydrogen bonds. The shear stress generated by flowing the aqueous Alg solution inside the capillary cannot induce deformation of its rigid assembly, results in the single thick gel filament. By complexation with PEG, destruction of regular hydrogen bond was responsible for breaking the rigid structure of Alg. Thus, deformation of Alg/PEG assembly was enabled to elongate as the fibrous structure by the shear stress, followed by gelation in contact with Ca2+ ions at the outlet of the inner capillary. Such shear-induced deformation of the Alg/PEG assembly was studied by measuring viscoelastic properties with a spindle viscometer. Besides, Alg/PEG assembly generation in each phase was determined by size-exclusion chromatography with a multi angle light scattering detector. This presentation will discuss a simple technique for preparing multiple gel filaments simply by passing a polymer solution through a capillary.
Anion-Dependent Perturbations in Ionic Liquid Structure Probed By High-Energy X-Ray Scattering
Authors: Coulthard Riley , Pham Tuan Anh , Zobel Mirijam , Buchsbaum Steven , Plata Desirée , Wood Brandon C. , Fornasiero Francesco , Meshot Eric 
Published: February 2020

Room-temperature ionic liquids (ILs) are molten salts at room temperature, and their wide electrochemical windows and high ionic conductivities make them promising next-generation electrolytes for energy storage devices. The vast potential cation-anion pairings result in tunable structure and organization of the bulk ILs, which ultimately dictates their properties. However, the amorphous structure of bulk ILs remains poorly understood due to the typically large and flexible nature of the molecules and complex interactions between them.
We employed high-energy synchrotron X-ray scattering to study the structure of a set of archetypal imidazolium-based ILs. We sought to understand perturbations in the structure across 3 popular anions possessing distinctly different geometric features and dipole moments (i.e., PF6
-, OTf-, TFSI-), while also systematically varying the length of the alkyl chain on the cation. In particular, we collected scattering at both high and low angles to compare local and longer-range structural order, respectively, and we leveraged pair distribution function (PDF) analysis to transform our X-ray data to real-space density fluctuations for intuitive inspection and quantitative comparison with simulations. Both classical and ab-initio molecular dynamics (MD) cross-validated these detailed intra- and intermolecular density distributions rendered by our X-ray experiments. This enabled us to use MD to decouple and characterize cation-anion, cation-cation, and anion-anion interactions as well as H-bonding type interactions for each IL studied.
Developing such analytical frameworks for detailed analysis of bulk IL structure as a function of different ions is important toward developing guidelines for engineering cations and anions for targeted applications. Furthermore, understanding the influence of interchanging ions is a prerequisite for applications in which ILs interface with other species, such as other types of ions, nanoparticles, or electrode interfaces.
(Invited) Plasmon−Plasmon Interactions and Radiative Damping of Plasmons in Graphene Nanoribbon Arrays
Authors: Perebeinos Vasili 
Published: February 2020

While graphene absorbs only 2.3% in the mid infra red (IR) spectral region, graphene plasmons have much stronger absorption in the far IR. Plasmons tunability by the external electric fields and by the spatial confinment offer a promising platform for opto-electronic and sensor applications. In this work [1], we demonstrate both theoretically and experimentally that the plasmon−plasmon and plasmon−radiation interactions modify strongly the plasmon resonance energy, radiative damping, and oscillator strength in graphene nanoribbon arrays. Even for the moderate filling factors of about 50%, plasmon radiative lifetime reduces to a ps time scale from a convetional ns time scale in the isolated graphene nanoribbon. We find scaling of plasmons with respect to the graphene doping level and filling factor, which both modify the strength of the long-range Coulomb and plamson-radiative interactions. The surprisingly large plasmon energy shift and radiative damping significantly affect the graphene-based plasmonic device performance.
[1] Vyacheslav Semenenko, Simone Schuler, Alba Centeno, Amaia Zurutuza, Thomas Mueller, and Vasili Perebeinos, ACS Photonics 5, 3459–3465, 2018.
(Invited) Covalent Functionalization of Graphene and MoS2: Chemical Versus Electrochemical Routes
Authors: Mali Kunal S. , De Feyter Steven 
Published: February 2020

Atomically thin sheets of materials, the so-called two-dimensional (2D) materials arrived on the scene in early 2000s with the successful isolation of graphene as freestanding monolayer films. Graphene, a single atom thick sheet of sp2-hybridized carbon bonded in a honeycomb lattice, has exceptional electronic, optical, mechanical and thermal properties that outperform those of most of the existing materials. The research on graphene further fuelled emergence of related 2D materials such as black phosphorous, silicene, germanene and transition metal dichalcogenides (TMDs) such as MoS2. Due to their exotic properties, these materials offer virtually endless opportunities for fundamental research as well as cutting edge applications.
Most of these 2D materials however exist as single layers only when supported by another solid surface or when stabilized by physisorbed or chemisorbed organic molecules. Given their layered nature, most 2D materials are extremely difficult to disperse in typical solvents. Chemisorption of organic molecules onto their basal plane allows dispersion of these materials in (organic) solvents thereby improving their solution processability. Such dispersions can be used in composite materials and as functional inks. Moreover, covalent functionalization allows modification of the intrinsic electrical, electronic and optical properties of these 2D materials.
In this talk, I will discuss covalent modification graphene, graphite and MoS2 using diazonium chemistry. Two different routes for reductive decomposition of diazonium salts namely, chemical and electrochemical, will be discussed in detail. Special focus is on sub-nanometer characterization of modified materials using scanning tunneling and atomic force microscopy (STM and AFM). Initial results towards patterned covalent functionalization using physisorbed self-assembled templates will also be presented besides the discussion on the use of such surfaces as seed layers for atomic layer deposition (ALD).
Fabrication of Efficient Perovskite Solar Cells in Ambient Air Using a Humidity-Insensitive Method
Authors: Wang Feng , Ye Zongbiao , Sarvari Hojjatollah , Park So Min , Abtahi Ashkan , Graham Kenneth , Zhao Yuetao , Chen Zhi , Li Shibin , Wang Yafei 
Published: February 2020

Fabrication of perovskite solar cells (PSCs) in ambient air is of challenge due to its sensitivity to humidity. In this presentation, we report the fabrication of efficient CH3NH3PbI3 (MAPbI3) PSCs using an antisolvent method which yields decent device performance in a wide range of humidity levels (~ 0% RH, 20% RH, 40% RH, 50% RH and 60% RH). The MAPbI3 films obtained in those conditions are studied by characterizations including scanning electron microscope (SEM), X-ray diffraction (XRD), UV-vis absorption and steady-state photoluminescence (PL). Results exhibit that the quality of the MAPbI3 films shows no obvious difference as a whole. The greatly suppressed influence of humidity is ascribed to the rapid crystallization process due to the antisolvent method. The photovoltaic performances for the devices prepared at these relative humidity (RH) levels are found similar with average power conversion efficiencies (PCE) are around 15%. The storage stability is found similar as well. What’s more, the effect of water absorbed in the hydrophilic precursor to MAPbI3 films and associated solar cells is investigated and found ignorable. As a result, it is concluded that antisolvent method is an ideal humidity-insensitive route to fabricate efficient PSCs in ambient air and may pave the way for massive and low-cost manufacturing of solar panels.
Keywords: (perovskite solar cells, CH3NH3PbI3, anti-solvent method, crystallization process)
Thermodynamic Approach to Develop Lead-Free Halide Perovskites: Theoretical Study
Authors: Park Jong Goo , Chung Choong-Heui , Hong Ki-Ha 
Published: February 2020

Metal halide perovskites (MHPs) are one of the promising candidates for next-generation photovoltaic materials. Since the Miyasa group first adopt methylammonium lead tri-iodides as a sensitizer of dye-sensitized solar cells, the efficiency of MHP solar cells has improved at an unprecedented speed. According to the recent report of national renewable energy laboratory, the certified power conversion efficiency (PCE) of MHP solar cells exceeded 23%. However, stability and toxicity are primary concerns for MHP solar cell commercialization. Among various efforts to develop Pb-free perovskite solar cells, Sn-based materials have shown the PCE. However, the stability of Sn-based perovskites is worse than Pb-based solar cells, and the multivalent features of Sn are considered to be the origin of the unstable performance.
Compositional engineering and additive control can be the effective ways to develop highly stable and efficient Pb-free perovskite solar cells. This study presents the effects of compositional engineering and various additives on the stabilization of Pb-free MHP materials via ab initio thermodynamics calculations. The concept of the ‘anti-stabilizer’ for the proper selection of the preferred phase is suggested by our previous report[1]. We present that the anti-stabilizing concept can be successfully applied to stabilize the proper band gap polymorph of black CsSnI3[2]and Bi-based layered perovskites. Additionally, the roles of additives including small alkali metal interstitials are discussed concerning thermodynamics.
[1] J. Jeon, T. Eom, E. Lee, S. Kim, S. Kim, K.-H. Hong, H. Kim, J. Phys. Chem. C 121 (2017) 9508–9515.
[2] J.H. Heo, J. Kim, H. Kim, S.H. Moon, S.H. Im, K.-H. Hong, J. Phys. Chem. Lett. 9 (2018) 6024–6031.
(Invited) Construction of Organic and Inorganic Hybrid Nanomaterials Utilizing Acene Derivatives for Efficient Singlet Fission
Authors: Hasobe Taku , Sakai Hayato 
Published: February 2020

Singlet fission (SF) is highly expected to improve the solar energy conversion properties by generating two excitons from one photon absorption. Among various organic compounds, acene derivatives such as tetracene and pentacene are promising for occurrence of efficient SF. For example, pentacenes meet the energy-level matching condition between a singlet and two triplet states: [E(S1) ≥ 2E(T1)]. However, the molar absorption coefficients of pentacenes in the ca. 400–500 nm region are extremely limited, whereas quantum dots, such as CdSe/ZnS (QD), possess high fluorescence quantum yields and particle-size-dependent fluorescence wavelengths. Thus, a combination of QD (D) and pentacene (A) provides a system of both an enhanced light-harvesting efficiency throughout the solar spectrum and an efficient conversion of the harvested light into the triplet states by SF. Based on these points, m-phenylenebridged bis(triisopropylsilylethynyl) (TIPS)-pentacene dimer-functionalized QD was synthesized to examine the sequential photoinduced process from energy transfer to SF. In femtosecond transient absorption measurements, initial energy transfer from QD to pentacene (quantum yield: 87%) and subsequent SF were efficiently observed. The quantum yield of triplet states of pentacene units (Φ
T) based on the excitation of QD attained ~160%.[1] Additionally, the related molecular systems will be briefly discussed in this presentation.[2,3]

References

[1] Sakai, H.; Inaya, R.; Tkachenko, N. V.; Hasobe, T. Chem. Eur. J.
2018, 24, 17062-17071.
[2] Sakai, H.; Inaya, R.; Nagashima, H.; Nakamura, S.; Kobori, Y.; Tkachenko, N. V.; Hasobe, T. J. Phys. Chem. Lett.
2018, 9, 3354-3360.
[3] Nakamura, S.; Sakai, H.; Nagashima, H.; Kobori, Y.; Tkachenko, N. V.; Hasobe, T. ACS Energy Lett.
2019, 4, 26-31.
Synthesis, Photophysical and Electrochemical Redox Properties of Β-Octa and Hepta Substituted Chlorins and Porphyrins
Authors: Rohal Renu Kumari , Sankar Muniappan 
Published: February 2020

Conformationally distorted tetrapyrroles can be used as appropriate biomimetic model compounds as they resemble naturally occurring pyrroles and also find applications in material chemistry [1]. Also, fused chlorins and porphyrins are having potential biological and material applications [2]. Nitroporphyrins are good precursors as they undergo nucleophilic substitution reaction with wide range of Michael donors [3]. Nucleophilic addition at the β-position results in the formation of porphyrins as well as chlorins based on the temperature and size of active methylene compound which can be further converted to mono- and di-fused porphyrins [4]. Herein, we report the facile syntheses, spectroscopic and redox properties of hepta- and octa-substituted porphyrins and their fused derivatives. CuDFP(MN)2Br6 and CuMFP(MN)Br6 exhibited anodic shift in redox potentials as compared to precursor porphyrins and hence lower HOMO-LUMO gap was observed. In this presentation, we will describe about the synthesis, structural, spectral and intriguing electrochemical redox properties of fused porphyrins and chlorins.

Fig. 1. Molecular Structure of β-monofused porphyrins and comparative CVs of CuTPP, CuMFPMNBr6 and CuDFP(MN)2Br6.

References:
1. (a) Senge, M. O.; Medforth, C. J.; Sparks, L. D.; Shelnutt, J. A.; Smith, K. M. Inorg. Chem. 1993, 32, 1716. (b) Chaudhri, N.; Cong, L.; Grover, N.; Shan, W.; Anshul, K.; Sankar, M.; Kadish, K. M. Inorg. Chem. 2018, 57, 13213. (c) Kumar. R.; Sankar, M. Inorg. Chem. 2014, 53, 12706.
2. (a) Bartoli, J. F.; Mansuy, O.; Le, B.-O.; Ozette, K. L. B.; Palacio, M.; Mansuy, D. J. Chem. Soc., Chem. Commun. 2000, 827. (b) Kozyrey, A. N,; Chen, Y,; Goshwami, L. N,; Tabaczvnski, W. A.; Pandey, R. K. J. Org Chem. 2006, 71, 1949.
3. (a) Serra, V. I. V.; Pires, S. M. G.; Alonso, C. M. A.; Neves, M. G. P. M. S.; Tome, A. C.; Cavaleiro J. A. S. Heterocycl. Chem.
2013, 33, 35. (b) Siri, O.; Jaquinod, L.; Smith, K.M. Tetrahedron Lett. 2000, 41, 3583. (c) Wickramasinghel, A.; Jaquinod, L.; Nurco, D. J.; Smith, K.M. Tetrahedron Lett. 2001, 57, 4261.
4. (a) Chaudhari, N.; Grover, N.; Sankar, M. Inorg. Chem.
2018, 57, 11349. (b) Kalsbeck, W. A.; Seth, J.; Bocian, D. F. Inorg. Chem.
1996, 35, 7935.

Figure 1
Helical Supramolecular Porphyrin Assemblies
Authors: Haino Takeharu 
Published: February 2020

Supramolecular polymers are a class of molecular assemblies, which are held together by non-covalent interactions. Reversible nature of supramolecular polymers results in unique properties such as self-healing and stimuli-responsivity. Therefore, supramolecular polymers have attracted a great deal of interest in material science.
A bisporphyrin molecule, where two porphyrin rings are connected with a pyridyl linkage, demonstrates a unique head-to-head homodimeric associationthat is directed through a donor-acceptor interaction and a stacking interaction. A brand-new supramolecular polymer was fabricated by employing this unique supramolecular complex. The two bisporphyrin units needed to be connected with the butadiyne linkage to give rise to a homoditopic tetrakisporphyrin monomer 1. The formation of the self-complementary dimeric bisporphyrin at each end of 1 resulted in the supramolecular helical polymer. In this presentation, we will report the development of the chiral supramolecular polymer that is produced by cross-linking of the supramolecular helical polymer with a chiral bispyridine 2.

Figure 1
Photophysical and Electrochemical Studies of Β-Functionalized Arylaminoporphyrins
Authors: Prakash Kamal , Osterloh Ryan , Sankar Muniappan , Kadish Karl M. 
Published: February 2020

β-functionalized porphyrins possess interesting photophysical, electrochemical and conformational properties that can be useful for applications in the area of non-linear optics, catalysis and anion sensing.1
β-nitration, β-formylation and β-halogenation of porphyrins have been utilized to prepare starting compounds which can be further converted into mixed β-substituted porphyrins.2 Only a few porphyrins having carbon-heteroatoms at their β-position are known and their electronic and redox properties have not been explored in great detail as compared to other β-functionalized porphyrins. The versatility of this synthetic approach to achieve new mixed β-functionalized porphyrins was previously demonstrated in the synthesis of medicinally related compounds as well as new types of ligands and DSSC materials.3 The substitution of an arylamino group onto a porphyrin through C-N bond formation provides a good porphyrin substrate which differs from previous systems in term of its chemical and photophysical properties.
In the present paper, we report the synthesis and electrochemical characterization of β-arylaminodibromoporphyrins shown in Chart 1. Five arylamino porphyrins, represented as (Br2NH(X)PorM), were fully characterized by UV-Vis, Fluorescence, 1H NMR spectroscopy and cyclic voltammetry techniques.
DFT studies indicate planar to moderate non-planar conformations of the porphyrins, revealing the effect of the different arylamines on the porphyrin core. Absorption spectra exhibited much broader and blue shifted Soret bands with fewer Q bands as compared to the precursor and other tri-subtituted porphyrins.2 Reduced emission spectra and lower lifetimes were also observed due to the presence of two bromo group.
Electrochemical studies were performed under different solution conditions and the data compared with that of other tri-substituted porphyrins. Changing the arylamino group from phenylamine to naphthylamine and then to 4-nitro/cyanophenylamine significantly altered the redox potentials of these porphyrins. In this presentation, we will discuss the structural, spectral and electrochemical properties of the newly synthesized β-arylamino functionalized porphyrins.

References:

(a) The Poprhyrin Handbook; Kadish K. M., Smith, K. M., Guilard, R., Eds.; Academic Press: San Diego, 2000-2003; Vol. 1-20. (b) Hiroto, S.; Miyake, Y.; Shinokubo, H. Chem. Rev.
2017, 117, 2910.

(a) Bhyrappa, P. Tetrahedron Lett.
2016, 57, 5150. (b) Kumar, R.; Sankar, M. Inorg. Chem.
2014, 53, 12706. (c) Prakash, K.; Kumar, R.; Sankar, M. RSC Adv.
2015, 5, 66824.

Higashino, T.; Imahori, H. Dalton Trans.
2015, 44, 448.

Figure 1
Prospects and Challenges of Supramolecular Approaches in Corrosion Prevention Strategies
Authors: Saji Viswanathan S. 
Published: February 2020

Supramolecular chemistry, the ‘chemistry of molecular assemblies’ is a fascinating realm of modern science where researchers are constantly investigating the possibilities of the design of novel supramolecular structures, surfaces and techniques in different application areas including corrosion prevention. Supramolecular species are branded by the three-dimensional arrangement of their constituents and by the nature of the intermolecular interactions [1, 2]. They can be conveniently classified into (i) molecular self-assemblies, (ii) host-guest complexes, and (iii) molecules built to specific shapes (rotaxanes, dendrimers etc.). A supramolecular self-assembly can be defined as the spontaneous organization of a few or many components forming structurally well-defined supramolecules through non-covalent interactions in a given set of conditions. In the host-guest chemistry, a host (a large molecule, aggregate or a cyclic compound possessing cavity) binds a guest (another molecule) yielding a host-guest complex (supramolecule).
Corrosion is inevitable and causes material destruction and component failures [3, 4]. Recently, supramolecular concepts have found extensive interest in Corrosion Science and Technology where areas like smart coatings have been widely studied. The presentation aims to provide a comprehensive outlook on applications and potentials of supramolecular chemistry in corrosion prevention. The research advancements in this area will be presented under two subheads: surface coatings and corrosion inhibitors (Figure 1). In each section, advancements in polymeric, host-guest based systems, organic-inorganic hybrid systems, and other supramolecular structures and techniques will be discussed [5]. Recent updates in this area will be presented along with a few of our ongoing research efforts on mesoporous silica-based host-guest systems. Existing challenges to practical applications will be debated.

References

J.M. Lehn, Proc. Natl. Acad. Sci. USA, 2002, 99, 4763-4768.

J.W. Steed, J.L. Atwood, Supramolecular chemistry, Wiley, 2000, ISBN 978-0-470-51234-0.

V.S. Saji, J. Thomas, Current Science, 2007, 92, 51-55.

V.S. Saji, R. Cook, Corrosion control and prevention using nanomaterials, 2012, Elsevier Science, ISBN: 978-1-84569-949-9.

V.S. Saji, Corrosion Reviews,
2019, Submitted.

Figure 1