THREE-DIMENSIONAL WATER NETWORKS SOLVATING AN EXCESS POSITIVE CHARGE: NEW INSIGHTS INTO THE MOLECULAR PHYSICS OF ION HYDRATION

: As compared to other nano polymers, dendrimers have novel three dimensional, synthetic hyperbranched, nano-polymeric structures. The characteristic of these supramolecular dendritic structures has a high degree of significant surface as well as core functionality in the transportation of drugs for targeted therapy, specifically in host-guest response, gene transfer therapy and imaging of biological systems. However, there are conflicting shreds of evidence regarding biological safety and dendrimers toxicity due to their positive charge at the surface. It includes cytotoxicity, hemolytic toxicity, haematological toxicity, immunogenicity and in vivo toxicity. Therefore to resolve these problems surface modification of the dendrimer group is one of the methods. From that point, this review involves different strategies which reduce the toxicity and improve the biocompatibility of different types of dendrimers. From that viewpoint, we broaden the structural and safe characteristics of the dendrimers in the biomedical and pharmaceutical fields.

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Synthesis, crystal structure and Hirshfeld analysis of a new crystalline modification of the radical ion salt octamethylenetetrathiafulvalenium triiodide (OMTTF)I3

Acta Crystallographica Section E Crystallographic Communications ◽

10.1107/s2056989018013907 ◽

2018 ◽

Vol 74 (11) ◽

pp. 1547-1552

Author(s):

Adriano Bof de Oliveira ◽

Johannes Beck ◽

Jörg Daniels

Keyword(s):

Positive Charge ◽

Three Dimensional ◽

Radical Cations ◽

Inversion Symmetry ◽

Formula Unit ◽

Crystalline Modification ◽

Asymmetric Unit ◽

Dimensional Network ◽

Hirshfeld Analysis ◽

Centrosymmetric Dimers

The reaction between 4,5,6,7-tetrahydro-2-(4,5,6,7-tetrahydro-1,3-benzodithiol-2-ylidene)-1,3-benzodithiole (common name: 4,4′,5,5′,6,6′,7,7′-octahydrodibenzotetrathiafulvalene, OMTTF) and an excess of iodine in tetrahydrofuran (THF) yielded the respective radical organic polyiodide salt, C14H16S4 +·I3 −. The asymmetric unit contains one and a half formula unit of both the cation and the anion, with the half-ions completed through inversion symmetry. The (OMTTF^\bullet+) positive charge can be assigned by the bond distances and the planar structure of the C2S2C=CS2C2 central fragment. In the crystal, trimers of triiodide anions are connected through secondary intermolecular I...I interactions into almost linear I9 3− polyanions. The non-centrosymmetric OMTTF radical cations are linked by S...S interactions into centrosymmetric dimers, while the centrosymmetric OMTTF cations remain as discrete units. The (OMTTF^\bullet+) radical cations and the triiodide anions are linked by weak C—H...I and C—H...S interactions into a three-dimensional network. This work reports the fourth crystalline modification of the C14H16S4^\bullet+·I3 − salt. The three previous modifications were obtained from a mixture of acetonitrile and toluene [Konarev et al. (2005). Synth. Met. 151, 231–238].

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Electrical and Polarimetric Radar Observations of a Multicell Storm in TELEX

Monthly Weather Review ◽

10.1175/mwr3421.1 ◽

2007 ◽

Vol 135 (7) ◽

pp. 2525-2544 ◽

Cited By ~ 73

Author(s):

Eric C. Bruning ◽

W. David Rust ◽

Terry J. Schuur ◽

Donald R. MacGorman ◽

Paul R. Krehbiel ◽

...

Keyword(s):

Electric Field ◽

Electric Fields ◽

Negative Charge ◽

Positive Charge ◽

Three Dimensional ◽

Phase Region ◽

Polarimetric Radar ◽

Radar Observations ◽

Mapping Array ◽

Lightning Initiation

Abstract On 28–29 June 2004 a multicellular thunderstorm west of Oklahoma City, Oklahoma, was probed as part of the Thunderstorm Electrification and Lightning Experiment field program. This study makes use of radar observations from the Norman, Oklahoma, polarimetric Weather Surveillance Radar-1988 Doppler, three-dimensional lightning mapping data from the Oklahoma Lightning Mapping Array (LMA), and balloon-borne vector electric field meter (EFM) measurements. The storm had a low flash rate (30 flashes in 40 min). Four charge regions were inferred from a combination of LMA and EFM data. Lower positive charge near 4 km and midlevel negative charge from 4.5 to 6 km MSL (from 0° to −6.5°C) were generated in and adjacent to a vigorous updraft pulse. Further midlevel negative charge from 4.5 to 6 km MSL and upper positive charge from 6 to 8 km (from −6.5° to −19°C) were generated later in quantity sufficient to initiate lightning as the updraft decayed. A negative screening layer was present near the storm top (8.5 km MSL, −25°C). Initial lightning flashes were between lower positive and midlevel negative charge and started occurring shortly after a cell began lofting hydrometeors into the mixed phase region, where graupel was formed. A leader from the storm’s first flash avoided a region where polarimetric radar suggested wet growth and the resultant absence of noninductive charging of those hydrometeors. Initiation locations of later flashes that propagated into the upper positive charge tracked the descending location of a polarimetric signature of graupel. As the storm decayed, electric fields greater than 160 kV m−1 exceeded the minimum threshold for lightning initiation suggested by the hypothesized runaway breakdown process at 5.5 km MSL, but lightning did not occur. The small spatial extent (≈100 m) of the large electric field may not have been sufficient to allow runaway breakdown to fully develop and initiate lightning.

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Halide Ion Micro-Hydration: Structure, Energetics, and Spectroscopy of Small Halide–Water Clusters

10.26434/chemrxiv.7636004.v1 ◽

2019 ◽

Author(s):

Pushp Bajaj ◽

Marc Riera ◽

Jason K. Lin ◽

Yaira E. Mendoza Montijo ◽

Jessica Gazca ◽

...

Keyword(s):

Water Clusters ◽

Quantitative Description ◽

Three Dimensional ◽

Many Body ◽

Ion Hydration ◽

Potential Energy Functions ◽

Hydrogen Bond Networks ◽

Correct Representation ◽

Dynamics Simulations ◽

Body Potential

<div> <div> <div> <p>Replica exchange molecular dynamics simulations and vibrational spectroscopy calculations are performed using halide-water many-body potential energy functions to provide a bottom-up analysis of the structures, energetics, and hydrogen-bonding arrangements in X−(H2O)n=3−6 clusters, with X = F, Cl, Br, and I. Independently of the cluster size, it is found that all four halides prefer surface-type structures in which they occupy one of the vertices in the underlying three-dimensional hydrogen-bond networks. For fluoride-water clusters, this is in contrast with previous reports suggesting that fluoride prefers interior-type arrangements, where the ion is fully hydrated. These differences can be ascribed to the variability in how various molecular models are capable to reproduce the subtle interplay between halide-water and water-water interactions. Our results thus emphasize the importance of a correct representation of individual many-body contributions to the molecular interactions for a quantitative description of halide ion hydration. </p> </div> </div> </div>

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Two 3-amino-1H-pyrazol-2-ium salts containing organic anions, and an orthorhombic polymorph of 3-amino-1H-pyrazol-2-ium nitrate

Acta Crystallographica Section E Crystallographic Communications ◽

10.1107/s2056989020015959 ◽

2021 ◽

Vol 77 (1) ◽

pp. 34-41

Author(s):

Sreeramapura D. Archana ◽

Channappa N. Kavitha ◽

Hemmige S. Yathirajan ◽

Sabine Foro ◽

Christopher Glidewell

Keyword(s):

Nitric Acid ◽

Hydrogen Bonds ◽

Fumaric Acid ◽

Positive Charge ◽

Three Dimensional ◽

Organic Anions ◽

Dilute Solution ◽

Related Compounds

Co-crystallization from methanol of 3-amino-1H-pyrazole with 3,5-dinitrobenzoic acid produces 3-amino-1H-pyrazol-2-ium 3,5-dinitrobenzoate monohydrate, C3H6N3 +·C7H3N2O6 −·H2O, (I), while similar co-crystallization of this pyrazole with an equimolar quantity of fumaric acid produces bis(3-amino-1H-pyrazol-2-ium) fumarate–fumaric acid (1/1), 2C3H6N3 +·C4H2O4 2−·C4H4O4, (II). The reaction of 3-amino-1H-pyrazole with a dilute solution of nitric acid in methanol yields a second, orthorhombic polymorph of 3-amino-1H-pyrazol-2-ium nitrate, C3H6N3 +·NO3 −, (III). In each of (I)–(III), the bond distances in the cation provide evidence for extensive delocalization of the positive charge. In each of (I) and (II), an extensive series of O—H...O and N—H...O hydrogen bonds links the components into complex sheets, while in the structure of (III), the ions are linked by multiple N—H...O hydrogen bonds into a three-dimensional arrangement. Comparisons are made with the structures of some related compounds.

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Wave Mechanics & Elements of Mathematical Physics

10.1093/oso/9780198822370.003.0005 ◽

2018 ◽

Author(s):

Peter Mann

Keyword(s):

Wave Equation ◽

Helmholtz Equation ◽

Separation Of Variables ◽

Three Dimensional ◽

Mathematical Physics ◽

Wave Mechanics ◽

Molecular Physics ◽

Classical Wave ◽

The One ◽

Dimensional Wave

This chapter presents an in-depth look at classical wave mechanics and mathematical physics, containing key examples directly relevant to molecular physics. The separation of variables is used to construct the Helmholtz equation from the one-dimensional wave equation before considering the three-dimensional wave equation. From this, equations for the temporal, radial, azimuth and angular components are developed and solutions using the Bessel equations and Legendre polynomials are found. Boundary conditions are explained and the Rayleigh plane wave expansion as the general solution to the Helmholtz equation is reconstructed. Both the Hermite equation and the Legendre equation are derived using the series solution method, and the Laplace equation is discussed.

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Graphite N–C–P dominated three-dimensional nitrogen and phosphorus co-doped holey graphene foams as high-efficiency electrocatalysts for Zn–air batteries

Nanoscale ◽

10.1039/c9nr04696h ◽

2019 ◽

Vol 11 (36) ◽

pp. 17010-17017 ◽

Cited By ~ 16

Author(s):

Liping Ge ◽

Dan Wang ◽

Peixia Yang ◽

Hao Xu ◽

Lihui Xiao ◽

...

Keyword(s):

Active Site ◽

High Efficiency ◽

Positive Charge ◽

Three Dimensional ◽

Nitrogen And Phosphorus ◽

Graphene Foams ◽

Co Doped

A C atom with a positive charge in the graphite N–C–P structure is the dominating ORR active site in N,P-HGFs.

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Carrier Accumulation in Silicon-On-Insulator Structures Containing Ge Nanocrystals in the Burried SiO2 Layer

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.108-109.77 ◽

2005 ◽

Vol 108-109 ◽

pp. 77-82

Author(s):

Ida E. Tyschenko ◽

A.A. Frantsuzov ◽

O.V. Naumova ◽

B.I. Fomin ◽

D.V. Nikolaev ◽

...

Keyword(s):

Physical Properties ◽

Positive Charge ◽

Silicon Layer ◽

Silicon On Insulator ◽

Electron Trapping ◽

Mos Transistors ◽

Electrical Field ◽

Excess Positive Charge ◽

Mos Structures ◽

Ge Nanocrystals

Electro-physical properties of metal-oxide-silicon (MOS) structures and MOS transistors, prepared in the top silicon layer of silicon-on-insulator (SOI) structures containing Ge nanocrystals in the buried SiO2 layers, have been studied. It was obtained that carrier accumulation in MOS structures depend on the direction of built-in electrical field in MOS structures. Accumulation of the excess negative charges in the case of p-channel transistors is associated with electron trapping on Ge nanocrystals synthesized in the buried dielectric. In the case of n-channel transistor, positive charge related to the Si/SiO2 interface or to the charged oxide is accumulated. The Ge atoms diffused to the SiO2/Si interface can stimulate the formation of the excess positive charge.

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Halide Ion Micro-Hydration: Structure, Energetics, and Spectroscopy of Small Halide–Water Clusters

10.26434/chemrxiv.7636004 ◽

2019 ◽

Author(s):

Pushp Bajaj ◽

Marc Riera ◽

Jason K. Lin ◽

Yaira E. Mendoza Montijo ◽

Jessica Gazca ◽

...

Keyword(s):

Water Clusters ◽

Quantitative Description ◽

Three Dimensional ◽

Many Body ◽

Ion Hydration ◽

Potential Energy Functions ◽

Hydrogen Bond Networks ◽

Correct Representation ◽

Dynamics Simulations ◽

Body Potential

<div> <div> <div> <p>Replica exchange molecular dynamics simulations and vibrational spectroscopy calculations are performed using halide-water many-body potential energy functions to provide a bottom-up analysis of the structures, energetics, and hydrogen-bonding arrangements in X−(H2O)n=3−6 clusters, with X = F, Cl, Br, and I. Independently of the cluster size, it is found that all four halides prefer surface-type structures in which they occupy one of the vertices in the underlying three-dimensional hydrogen-bond networks. For fluoride-water clusters, this is in contrast with previous reports suggesting that fluoride prefers interior-type arrangements, where the ion is fully hydrated. These differences can be ascribed to the variability in how various molecular models are capable to reproduce the subtle interplay between halide-water and water-water interactions. Our results thus emphasize the importance of a correct representation of individual many-body contributions to the molecular interactions for a quantitative description of halide ion hydration. </p> </div> </div> </div>

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N 6-Substituted 2-amino-4-chloro-5-formylpyrimidines: puckered versus planar pyrimidine rings, and hydrogen-bonded aggregation in zero, one, two and three dimensions

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768108019915 ◽

2008 ◽

Vol 64 (5) ◽

pp. 596-609 ◽

Cited By ~ 7

Author(s):

Justo Cobo ◽

Jorge Trilleras ◽

Jairo Quiroga ◽

Antonio Marchal ◽

Manuel Nogueras ◽

...

Keyword(s):

Hydrogen Bonds ◽

Electronic Structures ◽

Negative Charge ◽

Positive Charge ◽

Three Dimensional ◽

Three Dimensions ◽

Framework Structure ◽

Molecular Electronic ◽

Twist Boat ◽

Hydrogen Bonded

The structures of 12 new N 6-substituted 2-amino-4-chloro-5-formylpyrimidines, where the N 6 substituent is of the type NHR or NR 1 R 2, have been determined. The intramolecular dimensions provide strong evidence for the development of polarized, charge-separated molecular-electronic structures, with the positive charge delocalized over the two exocyclic amino N atoms and with negative charge on the formyl O atom. This polarization appears to be independent of the significant puckering, in seven of the compounds, of the pyrimidine rings from planarity towards boat, twist-boat or screw-boat conformations. In 11 of the compounds studied here, N—H...N hydrogen bonds link pairs of molecules into centrosymmetric R_2^2(8) dimer units, and their overall crystal structures are determined by the patterns of hydrogen bonds by which these units are further linked. Examples are reported in which no further hydrogen bonding occurs; in which the R_2^2(8) dimers are linked into chains of rings, or into sheets; and in which sheets are formed by the π-stacking of hydrogen-bonded chains of rings. In the sole structure lacking the R_2^2(8) dimer motif, N—H...O and N—H...N hydrogen bonds cooperate to generate a three-dimensional framework structure.

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