Materials Chemistry Commons^™

Hyperpolarized Porous Silicon Nanoparticles: Potential Theragnostic Material For 29si Magnetic Resonance Imaging, Hyeonglim Seo, Ikjang Choi, Nicholas Whiting, Jingzhe Hu, Quy S. Luu, Shivanand Pudakalakatti, Caitlin Mccowan, Yaewon Kim, Niki Zacharias Millward, Seunghyun Lee, Pratip Bhattacharya, Youngbok Lee

Nicholas Whiting

A Sodium Salt Of The Dimer Of Boronoterephthalic Acid Anhydride, Scott Simmons, Albert Fratini, Vladimir Benin

Albert Fratini

The title compound, sodium bis­(6-carb­oxy-1-hy­droxy-3-oxo-1,3-dihydro-2,1-benzoxaborol-1-yl)oxidanium, Na+·C16H15B2O13-, was prepared in two steps from 2-bromo-p-xylene. Its crystal structure was determined at 140 K and has triclinic (P) symmetry. The compound presents a unique structural motif, including two units of the cyclic anhydride of boronoterephthalic acid, joined by a protonated, and thereby trivalent, oxonium center. Association in the crystal is realized by complementary hydrogen bonding of the carboxyl groups, as well as by coordination of the sodium cations to the oxygen centers on the five-membered rings.

C–N Bond Rotation And E–Z Isomerism In Some N-Benzyl-N-Methylcarbamoyl Chlorides: A Dft Study, Michael Horwath, Vladimir Benin

Vladimir Benin

The current report presents the first theoretical study of the restricted CN bond rotation in carbamoyl chlorides. Several N-benzyl-N-methylcarbamoyl chlorides were investigated, with varying pattern of substitution in the aromatic ring. Optimizations and frequency calculations were conducted employing DFT at the B3LYP/6-31+G(d) level of theory. Each of the studied structures exhibits a pair of rotamers (s-Z and s-E), generated upon rotation around the C(O)N bond. The s-E isomer is the global minimum in every case, but the preference for it is usually less than 1 kcal/mol. Two possible transition state structures were identified for the rotamer interconversion: TSsyn and TSanti, …

Preparation And Characterization Of Some Substituted Benzyl N-Nitrosocarbamates Containing An N-2-(Methylthio)Ethyl Or A Bis(2-Aminoethyl)Sulfide Functionality, Satya Venkata, Eric Shamo, Vladimir Benin

Vladimir Benin

The synthesis and characterization of some substituted benzyl N-nitrosocarbamates with an N-2-(methylthio)ethyl or a bis(2-aminoethyl)sulfide functionality is reported, as a part of a long-term goal to design and prepare novel photolabile structures that could be used as substances for controlled release of alkylating and/or crosslinking agents. The synthesis was accomplished by reaction of benzyl chloroformates with the corresponding amines, resulting in the preparation of carbamates. The latter were subsequently nitrosated, utilizing two different N-nitrosation methods, to yield the target structures.

The Tetrafluoroborate Salt Of 4-Methoxybenzyl N-2-(Dimethylamino)Ethyl-N-Nitrosocarbamate: Synthesis, Crystal Structure And Dft Calculations, Helene Hedian, Vladimir Benin

Vladimir Benin

The tetrafluoroborate salt of 4-methoxybenzyl N-2-(dimethylamino)ethyl-N-nitrosocarbamate was prepared in two steps, via the corresponding carbamate. Its crystal structure is monoclinic, space group P21/c. The unit cell dimensions are: a = 19.499(8) Å, b = 5.877(3) Å, c = 15.757(7) Å, α = 90°, β = 110.019(7)°, γ = 90°, V = 1696.5(12) Å3, Z = 4. The structure exhibits an unexpected, pseudo-gauche conformation with respect to the C2–C3 bond, due to a stabilizing hydrogen bond between the carbonyl oxygen (O1) and the hydrogen atom at the trialkylammonium center (H3n), with a distance between them of 2.37 Å. DFT calculations on …

A Sodium Salt Of The Dimer Of Boronoterephthalic Acid Anhydride, Scott Simmons, Albert Fratini, Vladimir Benin

Vladimir Benin

The title compound, sodium bis­(6-carb­oxy-1-hy­droxy-3-oxo-1,3-dihydro-2,1-benzoxaborol-1-yl)oxidanium, Na+·C16H15B2O13-, was prepared in two steps from 2-bromo-p-xylene. Its crystal structure was determined at 140 K and has triclinic (P) symmetry. The compound presents a unique structural motif, including two units of the cyclic anhydride of boronoterephthalic acid, joined by a protonated, and thereby trivalent, oxonium center. Association in the crystal is realized by complementary hydrogen bonding of the carboxyl groups, as well as by coordination of the sodium cations to the oxygen centers on the five-membered rings.

Secondary N-Nitrosocarbamate Anions: Structure And Alkylation Reactions. A Dft Study, Vladimir Benin

Vladimir Benin

The current article reports theoretical studies (DFT: B3LYP/6-31+G(d)) on the structure and alkylation reactions of the anions of some secondary N-nitrosocarbamates, a class of ambident nucleophiles whose chemistry has been little explored. Several anions (1–4), with an increasing size of the carbamate alkyl (aryl) group were investigated, in an attempt to establish the influence of the size of that group on the thermal stability and regioselectivity of alkylation of the title anions. The conclusion is that thermal stability and the mode of reaction are affected significantly only in the presence of very large and branched carbamate groups. The thermal decomposition …

Preparation Of Phosphonoterephthalic Acids Via Palladium-Catalyzed Coupling Of Aromatic Iodoesters, Nathaniel Ivan, Vladimir Benin, Alexander Morgan

Vladimir Benin

The current article reports in detail the preparation of two phosphonoterephthalic acids: 2-phosphonoterephthalic acid (1) and 2,5-diphosphonoterephthalic acid (2). Efficient, scalable syntheses have been developed for both compounds based on Pd-catalyzed coupling reactions of iodinated terephthalate esters. Phosphonoterephthalic acids are potentially useful as flame-retardant additives or as monomers for the construction of acid-pendant polymer chains.

Preparation Of Some Substituted Terephthalic Acids, Susanna Branion, Vladimir Benin

Vladimir Benin

We report in detail the preparation of two substituted terephthalic acids: 2‐sulfomethylterephthalic acid (1) and 2‐phosphonoterephthalic acid (2). Efficient, short syntheses have been developed for both compounds. They are potentially useful monomers for construction of acid‐pendant polymer chains.

Theoretical Investigation Of A Reported Antibiotic From The 'Miracle Tree' Moringa Oleifera, Michael Horwath, Vladimir Benin

Vladimir Benin

Moringa oleifera, sometimes called the “Miracle Tree,” has received international attention for its potential to improve health in impoverished tropical areas. In addition to high vitamin content in the leaves and pods, the tree contains compounds with antioxidant and antibacterial properties. This study focused on the theoretical investigation of the suggested structure of one antibacterial compound, “pterygospermin,” whose existence was proposed after some studies of the roots of M. oleifera. The structure of pterygospermin was first proposed by a research group working in the 1950s, but later studies have not found evidence of this compound and have instead attributed the …

Synthesis And Flammability Testing Of Epoxy Functionalized Phosphorous-Based Flame Retardants, Vladimir Benin, Xuemei Cui, Alexander Morgan, Karl Seiwert

Vladimir Benin

Several potential new phosphorus-containing flame retardant molecules were evaluated for heat release reduction potential by incorporation of the molecules into a polyurethane, generated from methylene diphenyl diisocyanate and 1,3-propane diol. The heat release reduction potential of these substances was evaluated using the pyrolysis combustion flow calorimeter (PCFC). The polyurethanes were prepared in the presence of the potential flame retardants via solvent mixing and copolymerization methods to qualitatively evaluate their potential reactivity into the polyurethane prior to heat release testing. The functionality of the flame retardants was epoxide based that would potentially react with the diol during polyurethane synthesis. Flammability testing …

Synthesis And Flame Retardant Testing Of New Boronated And Phosphonated Aromatic Compounds, Vladimir Benin, Sravanthi Durganala, Alexander Morgan

Vladimir Benin

The present report describes the preparation and use of some dimethyl terephthalate derivatives in transition metal-catalyzed coupling reactions to produce new reactive flame retardants. Dimethyl iodoterephthalate and dimethyl 2,5-diiodoterephthalate were successfully employed in the preparation of phosphonic and boronic esters and acids. The latter were tested for heat release with a microcombustion calorimeter (ASTM D7309) to determine the potential for heat release reduction of these flame retardant molecules. The results showed that the addition of boronic or phosphonic acids greatly lowered the heat release, due to a condensed phase (char formation) mechanism. Adding ester groups to the boronic acids or …

Heat Release Of Polyurethanes Containing Potential Flame Retardants Based On Boron And Phosphorus Chemistries, Vladimir Benin, Bastien Gardelle, Alexander Morgan

Vladimir Benin

Using a polyurethane of methylene diphenyl isocyanate and 1,3-propane diol, several new non-halogenated aromatic boron and phosphorus flame retardants were evaluated for heat release reduction potential using the pyrolysis combustion flow calorimeter (PCFC). The polyurethanes were prepared in the presence of the potential flame retardants via solvent mixing and copolymerization methods, and were then analyzed via spectroscopic methods to determine if the flame retardant was still present in the final product. PCFC testing on the resulting products showed that the flame retardant molecule can have different effects on heat release depending upon how it is mixed into the polyurethane. Some …

Preparation, Characterization And Dft Studies Of Some New N-Nitrosocarbamates And N-Nitrosoureas, Ragavan Narayanan, Helene Hedian, Eric Shamo, Vladimir Benin

Vladimir Benin

We are presenting the preparation, characterization and density functional theory (DFT) studies {B3LYP/6-31+G(d)) of several reiated classes of N-nitrosocarbamates and N-nitrosoureas. The iong-range goal is the design and preparation of compounds, which would undergo photochemical or hydrolytic decomposition, to yield stabilized cyclic cations that can serve as alkylating agents at various nucleophilic centers, including DNA bases.

Synthesis, Structural Studies And Desilylation Reactions Of Some N-2-(Trimethylsilyl)Ethyl-N-Nitrosocarbamates, Arpitha Thakkalapally, Vladimir Benin

Vladimir Benin

The present report describes the preparation and characterization of several N-2-(trimethylsilyl)ethyl-N-nitrosocarbamates, designed as precursors to thermally unstable secondary N-nitrosocarbamate anions via fluoride-assisted cleavage. X-ray structural studies demonstrate that the core N-nitrosocarbamate moiety has a nearly planar geometry, with an s-E orientation at the N–N bond. DFT calculations (B3LYP/6-31+G(d)) reproduce accurately the structural features of the title compounds and detailed conformational analysis at the same level of theory addresses the long-standing issue of preferred geometries for three classes of related structures: N-nitrosocarbamates, N-nitrosoureas and N-nitrosoamides. Desilylation studies demonstrate that both the …

Reactions Of Methyl Perfluoroalkyl Ethers With Isopropyl Alcohol: Experimental And Theoretical Studies, Howard Knachel, Vladimir Benin, Chadwick Barklay, Janine C. Birkbeck, Billy D. Faubion, William E. Moddeman

Vladimir Benin

The reaction of an isomeric mixture of the methyl perfluoroalkyl ether, C4F9OCH3 (Novec-7100), in the presence of isopropyl alcohol (IPA) and/or water has been studied by measuring the rate of product formation using an ion-selective electrode (ISE) for fluoride ion, Karl Fisher coulometric titrations for water, and 1H and 19F NMR spectroscopy for product identification and rate studies. The results showed the methyl perfluoroalkyl ether to be very stable with products forming at the rate of ∼1 ppm per year at a laboratory temperature of 20 °C. Measurements over the temperature range of 6° to 100 °C were made on …

Preparation Of Halogenated Derivatives Of Thiazolo[5,4-D]Thiazole Via Direct Electrophilic Aromatic Substitution, Vladimir Benin, Alan T. Yeates, Douglas Dudis

Vladimir Benin

Chlorination and bromination reactions of thiazolo[5,4-d]thiazole led to the generation of its mono- and dihalogenated derivatives. These are the first instances of successful direct electrophilic aromatic substitution in the thiazolo[5,4-d]thiazole ring system. X-ray analysis demonstrates that both 2-bromothiazolo[5,4-d]-thiazole and 2,5-dibromothiazolo[5,4-d]thiazole are planar structures, with strongly manifested π-stacking in the solid state. Theoretical analysis of the pyridine-catalyzed halogenation (MP2/6-31+G(d) and B3LYP/6-31+G(d)calculations) reveals that introduction of one halogen actually leads to a slightly enhanced reactivity towards further halogenation. Several halogenation mechanisms have been investigated: 1) The direct C-halogenation with N-halopyridine as electrophile; 2) C-halogenation viaintermediate N-halogenation, and 3) C-halogenation following an addition …

Structure, Theoretical Studies And Coupling Reactions Of Some New Cyclic Boronic Esters, Andrew Kuttler, Sravanthi Durganala, Albert Fratini, Alexander Morgan, Vladimir Benin

Vladimir Benin

The present report describes the X-ray structural and theoretical studies of some new pinacolboronate esters, and it also outlines the use of the target structures in Suzuki coupling reactions to produce new aromatic or heteroaromatic esters and amides. X-ray structural analysis of the studied compounds revealed that the pinacolborane ring's position with respect to the benzene ring varies, depending on the particular environment. An ortho-positioned carboxylic ester (methyl ester) causes a nearly perpendicular orientation of the pinacolborane unit with respect to the benzene ring, whereas an ortho-positioned amide (N,N-dimethylamide) causes the pinacolborane unit to orient itself nearly coplanar. A plausible …

Editorial Of Special Issue: Nanomaterials As Photocatalysts, Mohammad Mansoob Khan Dr

Dr. Mohammad Mansoob Khan

This thematic special issue entitled “Nanomaterials as Photocatalysts” based on selected research/review articles submitted to the Journal of Saudi Chemical Society focuses on the visible/UV light photocatalytic activities of the selected nanomaterials. Topics of these research/review articles cover diverse and exciting areas of research related to nanomaterials such as metal oxides, nanoparticles, nanocomposites, their synthesis, and photocatalysis for waste water treatment, photocatalysis for effective conversion of waste, photochemical conversions, energy generation and other chemical energy production.

Electrically Conductive Polyaniline Sensitized Defective-Tio2 For Improved Visible Light Photocatalytic And Photoelectrochemical Performance: A Synergistic Effect, M O. Ansari, Mohammad Mansoob Khan Dr, S A. Ansari, M H. Cho

Dr. Mohammad Mansoob Khan

Sulfonated polyaniline@pure-TiO2 (s-Pani@p-TiO2) and polyaniline@defective-TiO2 (s-Pani@m-TiO2) nanocomposites were prepared by the in-situ oxidative polymerization of aniline in the presence of TiO2 (p-TiO2 and m-TiO2) nanoparticles followed by sulfonation with fuming sulfuric acid. Defect-induced TiO2 (m-TiO2) nanoparticles were obtained by an electron beam (EB) treatment of commercial TiO2 (p-TiO2) nanoparticles. The resulting s-Pani@p-TiO2 and s-Pani@m-TiO2 nanocomposites were characterized by UV-visible diffuse absorbance spectroscopy, photoluminescence spectroscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Polyaniline (Pani) was dispersed uniformly over the defective m-TiO2 surface with intimate contact on the interface to act cooperatively with the defects introduced deliberately to achieve remarkably …

Biogenic Synthesis Of A Ag–Graphene Nanocomposite With Efficient Photocatalytic Degradation, Electrical Conductivity And Photoelectrochemical Performance, Mohammad Mansoob Khan Dr, Mohammad Ehtisham Khan, M. H. Cho Prof

Dr. Mohammad Mansoob Khan

This paper reports the environmentally benign, simple, cost efficient, one-step, surfactant free, and biogenic synthesis of silver-graphene (Ag-Graphene) nanocomposite using an electrochemically active biofilm (EAB). The EAB was used for the reduction of Ag+ to Ag0 onto the graphene sheets. The morphology, structure, composition, and optical properties and contact angle of the Ag-Graphene were obtained using a range of techniques which confirmed the anchoring/presence of silver nanoparticles (AgNPs) onto the graphene sheets. The photocatalytic activity of the Ag-Graphene was evaluated by the degradation of methylene blue and Congo red dye in aqueous solution at an ambient temperature in dark and …

Polythiophene Nanocomposites For Photodegradation Applications: Past, Present And Future, Mohammad Mansoob Khan Dr, M. O. Ansari, S. A. Ansari, M. H. Cho

Dr. Mohammad Mansoob Khan

Polythiophene (PTh) has been the subject of considerable interest because of its good environmental stability, unique redox electrical behavior, stability in doped and neutral states, ease of synthesis, and wide range of applications in many fields. Apart from its applications in the electrical or electronic field, PTh has shown promising applications in photocatalytic degradation. The fabrication of a catalyst, metal oxides with PTh, extends the absorption range of the modified composite system, thereby enhancing the photocatalytic activity under UV or visible light irradiation. Substituted PTh, such as alkyl substitution, modifies the electronic properties of the polymer, thereby enlarging the potential …

Zno/Cdo Nanocomposites For Textile Effluent Degradation And Electrochemical Detection, Mohammad Mansoob Khan Dr

Dr. Mohammad Mansoob Khan

In this report, the photocatalytic and electrochemical activity of ZnO and ZnO/CdO nanocomposites were determined. Pure ZnO and nanocomposite ZnO/CdO were prepared by a vapor to solid mechanism and were characterized by different physical and chemical techniques. The CdO-modified ZnO possessed high efficiency to degrade textile effluent. It also showed high efficiency of degradation, such as 98% for methylene blue and 93% for methyl orange. Cadmium oxide (impurity) plays an important role in achieving zinc oxide materials that exhibit UV to visible light degradation of textile effluent. Additionally, uric acid sensing performed to study the electrochemical activity revealed that ZnO/CdO …

Silver Nanoparticles And Defect-Induced Visible Light Photocatalytic And Photoelectrochemical Performance Of Ag@M-Tio2 Nanocomposite, Mohammad Mansoob Khan Dr, S. A. Ansari, M. O. Ansari, M. H. Cho

Dr. Mohammad Mansoob Khan

An electrochemically active biofilm-assisted visible light active Ag@m-TiO2 photocatalyst was fabricated. The resulting nanocomposite was characterized by X-ray diffraction, transmission electron microscopy, diffuse absorbance/reflectance spectroscopy, photoluminescence spectroscopy, and X-ray photoelectron spectroscopy. The photocatalyst showed high photocatalytic activity and photoelectrochemical behavior due to the synergistic effect of the surface plasmon resonance (SPR) of Ag nanoparticles (AgNPs) and the induced defects in TiO2 (m-TiO2) nanoparticles. Ag@m-TiO2 nanocomposite showed much higher light harvesting ability because of the reduced band gap of m-TiO2 as well as the SPR characteristics of the AgNPs. The visible light photocatalytic experiments showed that the Ag@m-TiO2 nanocomposite possessed excellent …

Metal Oxides As Photocatalysts, Mohammad Mansoob Khan Dr

Dr. Mohammad Mansoob Khan

Metal oxides are of great technological importance in environmental remediation and electronics because of their capability to generate charge carriers when stimulated with required amount of energy. The promising arrangement of electronic structure, light absorption properties, and charge transport characteristics of most of the metal oxides has made possible its application as photocatalyst. In this article definition of metal oxides as photocatalyst, structural characteristics, requirements of the photocatalyst, classification of photocatalysts and the mechanism of the photocatalytic process are discussed.

Zno/Ag/Cdo Nanocomposite For Visible Light-Induced Photocatalytic Degradation Of Industrial Textile Effluents, Mohammad Mansoob Khan Dr

Dr. Mohammad Mansoob Khan

A ternary ZnO/Ag/CdO nanocomposite was synthesized using thermal decomposition method. The resulting nanocomposite was characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, UV–Vis spectroscopy, and X-ray photoelectron spectroscopy. The ZnO/Ag/CdO nanocomposite exhibited enhanced photocatalytic activity under visible light irradiation for the degradation of methyl orange and methylene blue compared with binary ZnO/Ag and ZnO/CdO nanocomposites. The ZnO/Ag/CdO nanocomposite was also used for the degradation of the industrial textile effluent (real sample analysis) and degraded more than 90% in 210 min under visible light irradiation. The small size, high surface area and synergistic effect in the ZnO/Ag/CdO …

Dc Electrical Conductivity Retention And Electrical Compensation Of Polyaniline By Tio2 At Higher Loading Percentages In Polyaniline@Tio2 Nanocomposites, Mohammad Mansoob Khan Dr, M. O. Ansari, S. A. Ansari, M. H. Cho

Dr. Mohammad Mansoob Khan

Electrically conductive HCl-doped polyaniline Pani)@titanium dioxide (TiO2) nanocomposites were prepared by the in-situ oxidative polymerization of aniline in the presence of different amounts of TiO2 nanoparticles. The synthesized Pani@TiO2 nanocomposites were confirmed by transmission electron microscopy, X-ray diffraction, UV-visible spectroscopy, and thermogravimetric analysis. The stability of the Pani@TiO2 nanocomposites in terms of their electrical conductivity retention was examined under isothermal and cyclic aging conditions, and compared with that of pure Pani. The Pani@TiO2 nanocomposites showed higher thermal stability than pure Pani. The effect of competitive doping/de-doping by TiO2 was examined at different Pani to TiO2 weight ratios. TiO2 at a …

Zno/Ag/Mn2o3 Nanocomposite For Visible Lightinduced Industrial Textile Effluent Degradation, Uric Acid And Ascorbic Acid Sensing And Antimicrobial Activity, Mohammad Mansoob Khan Dr

Dr. Mohammad Mansoob Khan

A facile and inexpensive route has been developed to synthesize a ternary ZnO/Ag/Mn2O3 nanocomposite having nanorod structures based on the thermal decomposition method. The as-synthesized ternary ZnO/Ag/Mn2O3 nanocomposite was characterized and used for visible light-induced photocatalytic, sensing and antimicrobial studies. The ternary ZnO/Ag/Mn2O3 nanocomposite exhibited excellent and enhanced visible light-induced photocatalytic degradation of industrial textile effluent (real sample analysis) compared to pure ZnO. Sensing studies showed that the ternary ZnO/Ag/Mn2O3 nanocomposite exhibited outstanding and improved detection of uric acid (UA) and ascorbic acid (AA). It also showed effective and efficient bactericidal activities against Staphylococcus aureus and Escherichia coli. These results …

Gold Nanoparticles-Sensitized Wide And Narrow Band Gap Tio2 For Visible Light Applications: A Comparative Study, Mohammad Mansoob Khan Dr

Dr. Mohammad Mansoob Khan

Gold nanoparticles (AuNPs)-sensitized wide band gap TiO2 (Au/P-TiO2) and narrow band gap TiO2 (Au/M-TiO2) nanocomposites were prepared using an electrochemically active biofilm. The optical and structural properties of the Au/P-TiO2 and Au/M-TiO2 nanocomposites were characterized using standard techniques. The surface plasmon resonance (SPR) absorption characteristics of the AuNPs on the TiO2 surface extended the absorption edge of P-TiO2 and M-TiO2 to the visible light region. The photocatalytic activity of the Au/P-TiO2 and Au/M-TiO2 nanocomposites was evaluated by the photodegradation of methylene blue and methyl orange, and 2-chlorophenol under visible light irradiation, where Au/M-TiO2 nanocomposite exhibited enhanced photocatalytic activity compared to …

Improved Electrode Performance In Microbial Fuel Cells And The Enhanced Visible Light-Induced Photoelectrochemical Behaviour Of Ptox@M-Tio2 Nanocomposites, Mohammad Mansoob Khan Dr

Dr. Mohammad Mansoob Khan

Visible light active PtOx@M-TiO2 and PtOx@P-TiO2 (x = 0, 1 and 2) nanocomposites were fabricated via a simple, green and environmentally benign process using an electrochemically active biofilm. The formation of the PtOx@M-TiO2 and PtOx@P-TiO2 nanocomposites was confirmed by X-ray diffraction, ultraviolet–visible–near infrared spectrophotometry, photoluminescence spectroscopy, and X-ray photoelectron spectroscopy (XPS). XPS revealed the presence of Pt0, Pt2+ (PtO) and Pt4+ (PtO2) species on the surface of M-TiO2 and P-TiO2. The presence of mixed valence states of PtOx on the surface of the PtOx@M-TiO2 nanocomposite and defect states in M-TiO2 helps absorb visible light more efficiently compared to the PtOx@P-TiO2 …