Dimethylamino Borane Research Articles

Simple, ultrasensitive detection of superoxide anion radical mutations in melanoma mice with SERS microneedles

Elevated levels of superoxide anion radicals (O2·−) have been implicated in the pathogenesis of a variety of diseases, such as cancer, inflammatory diseases and autoimmune diseases. To determine the O2·- concentration for assisting disease detection, a method based on surface-enhanced Raman scattering (SERS) combined with transparent polymer microneedles has been developed. Photocrosslinked NOA61 is used to prepare microneedles with sulfhydryl group, which can contribute to anchor gold nanoparticles (Au NPs) functionalized by p-mercaptobenzoic acid (PATP). This work successfully constructed SERS microneedles for in situ detection. A REDOX reaction occurred between PATP and O2·-, resulting in the formation of dimethylaminoborane (DMAB) and a subsequent change in Raman signal. Based on the quantitative relationship between the change of peak area ratio at 1042 cm−1 and 1077 cm−1 and the concentration change of O2·-, a standard curve with a linear range of 0–480 ng/mL was constructed. The SERS microneedles were effectively employed to track melanoma progression in mice, establishing a fundamental correlation between O2·- concentration and melanoma stage, as confirmed by ELISA. The benefits of this approach, including convenience, in situ applicability, and low cost, are anticipated to offer novel insights for non-invasive in situ detection, potentially enhancing disease monitoring and diagnosis.

Electroless Plating Cycle Process for High-Conductivity Flexible Printed Circuits

In this work, a non-formaldehyde electroless plating cycle process was successfully applied to prepare the flexible copper printed circuits on poly (ethylene terephtalate) (PET) films. Copper nanoparticles (Cu NPs) were employed as catalytic seeds, and dimethylaminoborane (DMAB) was used as the reductant. Cu NPs were directly printed on the PET surface modified by 3-mercaptopropyltriethoxysilane (MPTES) to serve as the seeds to trigger the electroless deposition. MPTES modification can dramatically improve the adhesion of the PET and Cu layer. Cu NPs can ideally substitute noble metals Ag, Pt, and Pd to catalyze electroless deposition. DMAB, as an innocuous reductant can replace formaldehyde in an alkalescent plating bath. The amount of Cu NPs with different sizes on the per area of the PET surface was investigated to determine its appropriate dosage. Various times, temperatures, concentrations of reactants in the electroless plating process were researched to obtain optimal deposition. The minimal sheet resistance of the copper pattern was 6 mΩ/sq with a resistivity of 2.01 μΩ·cm, which is 1.18 times that of bulk copper. These results demonstrated that the prepared Cu pattern had excellent conductivity. The kinetics of the electroless plating process was researched to quantify the thickness of the Cu layer and the consumption of reactants. The electroless plating bath can well be cycled after compensating reactants, while the sheet resistance of the Cu pattern fluctuated very little. The cycling electroless plating bath will greatly reduce the discharge of waste and is of vital significance for the large-scale and cheap manufacturing of flexible printed electronics.

A universal high-efficient and reusable “on–off” switch for the on-demand hydrogen evolution

Although a few “on–off” approaches such as the pH-adjusting, temperature-adjusting, and controlling by light upon photo-catalysts have been reported, the “on–off” control of the on-broad and on-demand hydrogen production still faces many challenges. Herein, we first report the usage of Zn2+/EDTA-2Na system as an unprecedented, universal, high-efficient, and reusable “on–off” switch for the on-demand H2 evolution upon the hydrolysis of ammonia borane, sodium borohydride and dimethyl aminoborane. This “on–off” switch has been demonstrated to be efficient and reusable in various heterogeneous and homogeneous metal catalysts for on-demand H2 evolution. The detailed characterizations have confirmed that Zn2+ ions attached and located at the surface of catalyst, covered its active sites on the surface, and turned off the H2 production. The H2 generation was switched on by the addition of EDTA-2Na, due to its strong coordination ability with Zn2+ ions. In addition, the Zn2+/EDTA-2Na switch has been successfully reused several times without any activity loss in the “on–off” control of H2 evolution. This switch is of great importance in the practical application for highly efficient, on-site and on-demand H2 evolution under ambient conditions.

Highly efficient overall-water splitting enabled via grafting boron-inserted Fe-Ni solid solution nanosheets onto unconventional skeleton

The aggregation of transition metal nanoparticles severely degrades their catalytic activity towards water splitting. Although this issue can be alleviated by the popular carbon-hybridization and metal foam-confinement strategies, the complicated fabrication procedure and the support corrosion parasitic in these strategies inevitably result in high usage cost and unsatisfactory cycle durability. Herein, we in-situ space-confined boron-inserted Fe-Ni solid solution nanosheets onto the activated hydrophilic sponge (B-FeNi@HS) via substitution of Fe by Ni and insertion of B within the Fe lattice interstitials in the presence of NH4+-modified dimethylamino borane solution. When served as the bifunctional electrocatalysts, B-FeNi@HS only needs overpotentials of 54 and 171 mV to afford 10 mA cm–2 for HER and OER in 1.0 M KOH, respectively. In addition, the alkaline overall-water splitting system constructed by using B-FeNi@HS as two-electrodes only delivers an ultralow cell voltage of 1.456 V to drive 10 mA cm–2, and shows negligible activity decay even at 500 mA cm–2 for 3 days. Such outstanding performance can be traced to the synergism of corrosion-resistant support, hierarchical morphology with favorable surface area and dual solid-solution crystal structure, ensuring robust mechanical stability, rapid charge/mass transfer kinetics as well as the energetically favorable formation of intermediates during catalysis. The proposed strategy is versatile and can be extended to synthesize other efficient B-inserted Fe-based electrocatalysts.

Fabrication of flexible copper patterns by electroless plating with copper nanoparticles as seeds

Flexible conductive copper patterns with low electric resistance, good adhesion, and high stability were successfully prepared on heat-sensitive polyethylene terephthalate (PET) substrate by combining the inkjet print with copper nanoparticles (Cu NPs) conductive ink and electroless plating (ELP) copper at room temperature. The Cu NPs served as the catalysts to promote copper ions electroless deposition on PET surface. Dimethylaminoborane (DMAB) was used as the reductant to place poisonous formaldehyde in the electroless plating process. The Cu patterns had a strong adhesion with PET substrate modified by 3-Mercaptopropyltriethoxysilane (MPTES) and would not fall even after 4000 cycles bending test. The electric resistivity of patterns could be as low as 5.43 μΩ·cm, which is about three times that of bulk copper. The minimum sheet resistance of the patterns was 54 mΩ/sq and had little change in the atmosphere for five months, that showed the patterns had an excellent anti-oxidation performance.

Microscopic insight into the single step growth of in-plane heterostructures between graphene and hexagonal boron nitride

Graphene-h-BN hybrid nanostructures are grown in one step on the Pt(111) surface by ultra-high vacuum chemical vapor deposition using a single precursor, the dimethylamino borane complex. By varying the deposition conditions, different nanostructures ranging from a fully continuous hybrid monolayer to well-separated Janus nanodots can be obtained. The growth starts with heterogeneous nucleation on morphological defects such as Pt step edges and proceeds by the addition of small clusters formed by the decomposition of the dimethylamino borane complex. Scanning tunneling microscopy measurements indicate that a sharp zigzag in-plane boundary is formed when graphene grows aligned with the Pt substrate and consequently with the h-BN layer as well. When graphene is rotated by 30°, the graphene armchair edges are seamlessly connected to h-BN zigzag edges. This is confirmed by a thorough density functional theory (DFT) study. Angle resolved photoemission spectroscopy (ARPES) data suggests that both h-BN and graphene present the typical electronic structure of self-standing non-interacting materials.

Dehydrogenation of Dimethylamine–Borane Catalyzed by Half-Sandwich Ir and Rh Complexes: Mechanism and the Role of Cp* Noninnocence

Half-sandwich Cp*RhIII complexes (Cp* = η5-1,2,3,4,5-pentamethylcyclopentadienyl) supported by 2,2′-bipyridine or 4,4′-di-tert-butyl-2,2′-bipyridine catalyze dehydrogenation of dimethylamine–borane (Me2NH·BH3) to produce H2 and dimethylamino–borane dimer (Me2N—BH2)2 with turnovers of 2200. The IrIII analogues, on the other hand, display dramatically poorer catalytic activity. Mechanistic inferences drawn from stoichiometric reactions and DFT calculations suggest noninnocent involvement of the Cp* moiety as a proton shuttle.

Sn<sup>IV</sup> and Zr<sup>IV</sup> Compounds of a <i>C</i><sub>3</sub>-Symmetric Ligand with Amine [ONN] and [ONNO] Coordination Sites

This contribution describes the synthesis and structural characterization of a triaminoguanidinium (TAG)-based ligand [H6(OMe)3Limin]BF4 (1) containing imine bonds (Limin) and its reduction with a dimethylamino borane complex to the corresponding amine compound (Lamin)[H9(OMe)3Lamin]OTs (2). In solution, both ligands are C3-symmetric but crystal structures show the great influence of the reduction on the molecular structure. We show that the planar imine ligand is converted to a highly flexible compound which has nine potential coordination sites, three phenoxy and six amine donors, for binding metal ions. First solid state structures of 1:1 (metal:ligand) coordination compounds with SnIV and ZrIV are presented. SnIV exhibits an octahedral coordination sphere and is bound in a facial [ONN] coordination pocket. ZrIV is pentagonal bipyramidal coordinated and the ligand stabilizes this with its’ [ONNO] binding sites.

(Invited) Cyborg Insect: Insect Computer Hybrid Robot

Insect-computer hybrid robot, often referred as to ‘Cyborg Insect’, is the fusion of living insect and miniature radio-enabled wireless electrical stimulator to control the locomotion of the insect platform in walking and flight. The miniature stimulator is mounted on the back of the living insect and metal thin wires are implanted into neuromuscular sites of our interest to electrically stimulate for eliciting experimentalist’s desired motor actions and behaviors. Insects exhibit amazing modes of locomotion. They float, swim, crawl, jump, run, fly and they even walk on water. They do this with such efficiency, sophistication and elegance of function across a vast size range that they have mastered locomotion on almost every terrain on the earth. Very recently researchers have started building ultra-small data recording systems for flying insects and tried to stimulate insects (moths, locusts, beetles) to induce desired actions. The miniature stimulator (~1.3 g in total mass) consisted of a custom PCB (printed circuit board), an off-the-shelf microcontroller, a rechargeable micro battery and thin-wire electrodes. We employed Mecynorhina torquata, a giant flower beetle as the insect platform for the hybrid robot (10 g, 6 cm, 3 g payload capacity in flight). The stimulator assembly was mounted on the beetle’s pronotum and the terminals of wire electrodes were inserted into the optic lobes, brain, basilar flight muscles and dorsal thorax (counter electrode). Flight initiation was triggered by applying 2 - 4 V, 100 Hz, 20 % duty cycle, biphasic square pulse trains between the two electrodes implanted into the optic lobes, massive neural clusters of compound eyes. Cessation was triggered by a single DC pulse applied to the same sites as the initiation. The wing power was decreased (and thus throttle down) when the same 100 Hz pulse trains were applied to the brain. Turnings were elicited by applying the same pulse trains to either the left or right basilar flight muscle. The beetle turned in opposite direction to stimulated side: left turn was, for example, conducted by the right side stimulation. On the other hand, toward a self-powering unit for the insect-computer hybrid robot, we have proposed a miniature biofuel cell implantable into living insect to generate electrical energy by consuming energy source, for example, saccharide. For that we have developed nanoparticle catalysts for oxygen reduction reaction such as P or B doped Pd, denoted by Pd-P or Pd-B. By doping these non-metal elements into Pd, the catalytic activity of Pd was drastivally enhanced. These Pd-P and Pd-B catalysts were facilely synthesized by a electroless deposition process using hypophosphate and DMAB (dimethylaminoborane) as reducing agent, respectively. In the presentation, we will show the demonstration of insect locomotion control and the experimental data and discussion on the enhanced catalytic activities of the Pd nanoparticle catalysts. Figure 1

SYNTHESIS AND ORGANIZATION OF PLATINUM NANOPARTICLES AND NANOSHELLS ON A NATIVE VIRUS BIOSCAFFOLD

A wild type virion, bacteriophage T4, was used as an organic template for the controlled synthesis and organization of Pt nanoparticles and nanoshells on its capsid. A long incubation of T4 virions with the metalchloride solution is necessary to the specific binding of the external surface of T4 capsid with PtIVby means of interactions between PtIVand the chemical functionality found inherently on the surface of the proteinaceous viral capsid. After chemical reduction with dimethylaminoborane (DMAB), the highly dispersive Pt nanoparticles with a uniform size of 3–4 nm were synthesized and covered the whole viral capsid. The packing density of Pt nanoparticles was enhanced by increasing the incubation cycles of the virions in metal salt solution. Moreover, Pt @T4 shell/core structures could be achieved by increasing the amount of metal ions around virons. UV/vis spectroscopy was used to follow the course of the reaction, and the formation mechanism was discussed. Both the small Pt nanoparticles and Pt @T4 shell/core structures show high electrocatalytic activity in electrochemical measurement, and therefore are expected to have potential applications in electrocatalysis.

Dimethylaminoborane-modified copolysilazane as a novel precursor for high-temperature resistant SiBCN ceramics

A novel polyborosilazane (PBSZ) precursor was synthesized by the reaction of copolysilazane (CPSZ) with dimethylaminoborane (DMAB). The resultant PBSZs were characterized by FT-IR and NMR spectroscopy. It was found that both, BH and NH bonds of DMAB, react with CPSZ leading to boron containing copolysilazanes. The polyborosilazanes were pyrolyzed at 900 °C in argon and the precursor-to-ceramic transformation was studied by TG-MS and FT-IR spectroscopy. The modification of CPSZ with DMAB enhances the cross-linking of the resulting PBSZ, which increases the final ceramic yield from 57.8% to 77.5–80.0%. Finally, the ceramics obtained at 900 °C were subsequently annealed at different temperatures ranging from 1200 to 1800 °C. The heat-treated products were characterized by X-ray powder diffraction and electron microscopy. Accordingly, the resulting SiBCN ceramics exhibit significantly enhanced high-temperature-resistance with respect to decomposition and crystallization as compared with boron-free CPSZ-derived SiCN ceramics. TEM results support that the thermal stability is due to the segregation of a BN(C) phase as interlayer between Si3N4 nanocrystals formed during heat-treatment of SiBCN at T > 1500 °C.

Effect of both protective and reducing agents in the synthesis of multicolor silver nanoparticles

In this paper, the influence of variable molar ratios between reducing and loading agents (1:100, 1:50, 1:20, 1:10, 1:5, 1:2, 1:1, 2:1) and between protective and loading agents (0.3:1, 0.75:1, 1.5:1, 3:1, 7.5:1, 30:1, 75:1) in the synthesis of silver nanoparticles by chemical reduction has been evaluated to obtain multicolor nanoparticles with a high stability in time. The protective agent poly(acrylic acid, sodium salt) (PAA) and reducing agent dimethylaminoborane (DMAB) play a key role in the formation of the resultant color. Evolution of the optical absorption bands of the silver nanoparticles as a function of PAA and DMAB molar ratios made it possible to confirm the presence of silver nanoparticles or clusters with a specific shape. The results reveal that a wide range of colors (violet, blue, green, brown, yellow, red, orange), sizes (from nanometer to micrometer), and shapes (cubic, rod, triangle, hexagonal, spherical) can be perfectly tuned by means of a fine control of the PAA and DMAB molar concentrations.

Polyamine-Promoted Growth of One-Dimensional Nanostructure-Based Silica and Its Feature in Catalyst Design

Crystalline linear polyethyleneimine (LPEI) is a fascinating polymer that can be used as a catalyst, template and scaffold in order to direct the formation of silica with controllable compositions and spatial structures under mild conditions. Considering the crystallization and assembly of LPEI is temperature-dependent, we adopted different accelerated cooling processes of a hot aqueous solution of LPEI in order to modulate the LPEI crystalline aggregates. We then used them in the hydrolytic condensation of alkoxysilane. A series of silica with nanofibrils, nanotubes and nanowire-based structures were achieved simply by the LPEI aggregates which were pre-formed in defined cooling processes. These specific one-dimensional nanoscale structures assembled into microscale fibers-, sheet- and platelet-like coalescences. Furthermore, the deposition kinetics was also researched by the combination of other characterizations (e.g., pH measurement, 29Si MAS NMR). As a preliminary application, the hybrids of LPEI@SiO2 were used not only as an agent for reducing PtCl42− into Pt but also as host for loading Pt nanoparticles. The Pt-loaded silica showed good catalytic properties in the reduction of Rhodamine B by dimethylaminoborane (DMAB).

ChemInform Abstract: Cationic Tricoordinate Boron Intermediates: Borenium Chemistry from the Organic Perspective

AbstractReview: 179 refs.

Preparation of Ni nanoparticles between montmorillonite layers utilizing dimethylaminoborane as reducing agent

Preparation of Ni nanoparticles between montmorillonite layers using dimethylaminoborane (DMAB) as a reducing agent is reported. The DMAB molecules are first intercalated into the interlayer space of Ni-montmorillonite (Ni-mont). Then, as a result of a heating process, the DMAB is decomposed to release electrons for the reduction of the Ni ions. From high-resolution TEM images, it is demonstrated that the deposited Ni nanoparticles with about 1-2 nm in size are formed uniformly over the entire area of the Ni-mont matrix. Considering the gallery height calculated by subtracting the silicate sheet thickness from the basal spacing (1.30 nm), the morphology of the formed Ni nanoparticles in the interlayer space is thought to be disc-like in shape with a thickness of 0.3-0.4 nm and an average lateral size of 1.2 nm.

Electroless Deposition of Silver on Multiwalled Carbon Nanotubes Using Iodide Bath

Electroless deposition of silver on multiwalled carbon nanotubes (MWCNTs) was investigated using an iodide bath. Prior to electroless deposition of silver, the MWCNTs were chemically oxidized and then pre-treated using a typical two-step method (sensitization and activation) to form catalytic palladium nuclei on the MWCNTs. Dimethylaminoborane (DMAB) was used to reduce silver ions. Electroless deposition of silver was carried out at 25°C with variation of the pH. The microstructure of the deposits was evaluated using field emission-scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The silver iodide complex ion species present was determined to be AgI43− from equilibrium potential measurements. Silver was selectively deposited on palladium nuclei on the surface of the MWCNTs and continuous diffusion of deposited silver and palladium nuclei resulted in a solid solution of Ag-Pd alloy particles on the MWCNTs at pH = 7.5.

"Inversed" Surface Micelle Array Fabrication of an Amphiphilic Block Copolymer on Water Surface

A mixed film of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) with 6-{4-[(4-hexylphenyl)azo]phenoxy}hexanoic acid (6Az5COOH) were prepared on water by co-spreading method. The resulting films were transferred onto mica at various surface pressures. Atomic force microscopy (AFM) and pi-A isotherm measurements revealed that both PS and p4VP blocks in PS-b-P4VP forms spread monolayer on water with the assist of 6Az5COOH at low surface pressures. Upon compression on water, we observed that the P4VP/6Az5COOH parts in the hybrid film are collapsed selectively at an early stage and form dot array morphology. In addition, gold cluster dots were deposited selectively on the dots in the dot array film by metallization based on deposition of HAuCl4 to the P4VP chain and reduction with dimethylamino borane. These results strongly support the fact that the "inversed" surface micelles are formed on water via hybridization of PS-b-P4VP with 6Az5COOH.

Amino olefin nickel(i) and nickel(0) complexes as dehydrogenation catalysts for amine boranes

A rare paramagnetic organometallic nickel(I) olefin complex can be isolated using the ligand bis(5H-dibenzo[a,d]cyclohepten-5-yl)amine. This complex and related nickel(0) hydride complexes show very high catalytic activity in the dehydrogenation of dimethylamino borane with release of one equivalent of dihydrogen.

Fabrication of Ni–B alloy coated vapor-grown carbon nanofibers by electroless deposition

Ni–B alloy coated vapor-grown carbon nanofibers (VGCNFs) were fabricated by electroless deposition and their microstructures were investigated. The effects of heat treatment on the coated VGCNFs were also studied. VGCNFs could be coated with a homogeneous Ni–B alloy film using a plating bath containing dimethylaminoborane (DMAB) as a reducing agent. The boron content of the Ni–B alloy film could be varied from 14 to 24 atom% B by varying the DMAB concentration of the plating bath. The VGCNFs were uniformly coated with a Ni–B alloy layer that was only several nanometers thick. The coating thickness on the VGCNFs could be controlled by varying the reaction time. The Ni–B alloy coatings formed in this study were semicrystalline or amorphous depending on the boron content of the alloy film. After heat treatment, the phase structure of the Ni–B alloy coatings changed to a stable crystalline structure consisting of a face-centered-cubic nickel phase and a Ni 3B phase. No cracks or exfoliation of the coatings were observed, even after heat treatment.

Elucidation of the chemical state of phosphorus and boron in crystallographically amorphous nickel electroplates

Using the valence-to-core version of X-ray emission spectroscopy (valence-to-core XES) together with X-ray diffraction analysis, the structure and the composition of nickel coatings deposited from solutions containing hypophosphite ions or dimethylaminoborane (DMAB) are studied. The diffraction patterns of prepared deposits are characterized by the presence of a wide “halo”. Annealing of crystallographically amorphous deposits at temperatures of 500°C and higher transforms these haloes into the spectra corresponding to metal nickel and its phosphides or borides present in the crystallized deposits. A result of fundamental importance obtained in the simultaneously conducted examination of the same deposits by the valence-to-core XES method is that both the binding energy and the intensities of Kβ satellite spectral lines of annealed samples remain unchanged as compared with original samples. Based on this comparison, it is concluded that phosphide and boride nickel compounds were already formed in the course of electrodeposition, whereas the thermal treatment of deposits (crystallization) leads only to aggregation of the metal and metal-metalloid nanoparticles.