Long-chain Aliphatic Amines Research Articles

Electrodeposition of Au Nanowires via Amine Ligand-Induced Active Surface Growth.

Amine ligands have been widely applied as morphology-directing reagents in nanostructure synthesis. In this work, we explored the application of the amine ligands in the active surface growth mechanism in place of the strong thiolated ligands. Despite being weaker compared to the thiols, amine ligands such as aniline were also shown to be capable of facilitating the template-less electrodeposition of Au nanowires (NWs) on the substrate via the active surface growth mechanism. Given the close binding difference between the amine-grafted substrate and the ligands, substrate functionalization becomes critically important for effective construction of the active surface and the growth of the nanowires. Additionally, the growth with the amine ligands took place at more positive reduction potentials and is less prone to splitting and bundle formation. A systematic generality study revealed that besides the aromatic amines, long-chain aliphatic amines were also capable of facilitating nanowire growth. Given the weak binding affinity of the amine ligands, the Au NWs are readily accessible for further processing to generate sophisticated one-dimensional structures. As a demonstration, tandem electrodeposition was performed to directly obtain coaxial core-shell Au@Pt NWs with adjustable length, diameter, and shell thickness.

Synthesis, characterization, and anticancer properties of iminopyridine platinum(II) complexes containing long aliphatic chains

A series of iminopyridine ligands were prepared from the condensation reaction of 6-methylpyridine-2-carboxaldehyde and long-chain aliphatic primary amines. Square planar platinum(II) complexes were synthesized from the reaction of [PtCl2(η2-coe)]2 (coe = cis-cyclooctene) with two equivalents of ligand. The synthesis of the platinum compounds appears to go through a five-coordinate trigonal pyramidal species where coe remains coordinated initially but eventually dissociates to afford the four-coordinate complexes. Ligands and platinum complexes were characterized using multi-nuclear NMR and FT-IR spectroscopies as well as an X-ray diffraction study for the platinum complex derived from n-hexylamine. The cytotoxic properties of the platinum complexes against the ovarian cancer cell line SKOV-3 using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric method were examined. Relative cytotoxicities of the platinum complexes follow a trend of greater potency with increasing chain length against the SKOV-3 cell line, with the longest aliphatic hydrocarbon chain (C16) exhibiting anticancer effects comparable to that of cisplatin.

Self-organization and tunable characteristic lengths of two-dimensional hexagonal superlattices of nanowires directly grown on substrates

The organization of nano-objects on macroscopic surfaces is a key challenge for the technological improvement and implementation of nanotechnologies. For achieving operational functions, it is required to assemble nano-objects as controllable building blocks in highly ordered superstructures. Herein, we demonstrate the growth and self-organization of metallic nanowires on surfaces into hexagonal superlattices with tunable characteristic lengths depending of the stabilizing surfactants employed. Starting from a reacting mixture containing a Pt(111) substrate, a Co organometallic precursor, an amine, and an acid dissolved in a solvent, we quantify the structural evolution of superlattices of vertical single-crystalline Co nanowires on Pt, using a combined analysis of small angle neutron scattering, transmission, and scanning electron microscopies. We show the concerted steps of a spontaneous growth and self-organization of the nanowires into two-dimensional (2D) hexagonal lattice on Pt, at intervals starting from a few hours of reaction to a highly ordered superlattice at longer times. Furthermore, it is shown that apart from long-chain acid and long-chain aliphatic amine pairs used as stabilizers, the combination of a long-chain aliphatic and a short-chain aromatic ligand in the synthesis can also be employed for the nanowire superlattices development. Interestingly, the possibility to employ different pairs allows quantitative modulation of the nanowire arrays, such as the interwire distance and the packing fraction.

Durable superhydrophobic melamine sponge based on polybenzoxazine and Fe3O4 for oil/water separation

Oil/water separation through superhydrophobic sponges is an important method for oily wastewater and organic solvents pollution treatments, and developing a simple and eco-friendly approach to fabricate superhydrophobic sponge is still very urgent and valuable. In this work, Fe3O4 and bio-benzoxazine based on cardanol and long-chain aliphatic amine were successively loaded on melamine sponge (MS) through a simple dip-coating method, which was thermally cured to obtain superhydrophobic MS. The as-prepared superhydrophobic MS (P15C-O/Fe3O4/MS) not only exhibited high oil absorption capacity from 65.8 to 136.2 times its own weight for various oils and organic solvents, but also showed excellent recyclability with a water contact angle (WCA) of about 149° after 50 absorbing-squeezing cycles and an absorption retention of more than 92% after 100 cycles. Moreover, P15C-O/Fe3O4/MS also possessed outstanding chemical stability, whose WCA almost kept unchanged after touching with strong acid (pH = 1) and alkali (pH = 13) as well as NaCl solutions for 48 h. The outstanding recyclability and stability of P15C-O/Fe3O4/MS were from the stability of polybenzoxazine and strong adhesion between the coating and sponge, due to the formation of coordination interactions between Fe3+ and N, O atoms as well as hydrogen bonds between polybenzoxazine and sponge. In addition, P15C-O/Fe3O4/MS could be used for continuous oil-water separation and driven remotely by a magnetic force. These advantages make P15C-O/Fe3O4/MS a potential candidate for large-area oil-spill cleanup and oily wastewater treatment, especially under some dangerous conditions.

Surface activity and cleaning performance of Gemini surfactants with rosin groups

Novel rosin-based Gemini surfactants (RGS-n) are synthesized from dehydroabietylamine and four different N, N-dimethyl long-chain aliphatic amines. Compared with traditional surfactants, the critical micelle concentration (CMC) of RGS-n is reduced by 2 to 3 orders of magnitude. The three-ring skeleton of dehydrogenated rosin can improve the emulsification of RGS-n. Besides, the Kraff points of RGS-n are less than 0 °C, indicating the availability of RGS-n at low temperature. RGS-n exhibits a better cleaning effect through the combination of electrostatic interaction with carboxyl groups of rosin and the emulsification of RGS-n. The smaller presence of residual rosin on printed circuit boards (PCBs) after cleaning with RGS-n indicates higher cleaning performance of RGS-n. The effect of the length of the hydrophobic chain on cleaning efficacy is analyzed for PCBs. Higher cleaning efficacy is observed at RGS-14. This work has specific research significance for Gemini surfactant application as a cleaning agent in industrial circuit board cleaning.

Broadband and sensitive two-dimensional halide perovskite photodetector for full-spectrum underwater optical communication

Full-spectrum underwater optical communication (UOC) is of great significance for major strategic needs including resource development, scientific exploration, and homeland security. As the core of the full-spectrum UOC system, photodetectors (PDs) are plagued by stringent requirements including a broadband response, intrinsic water resistance, and a high detectivity. In this work, two-dimensional (2D) halide perovskites (HPs) and corresponding PDs are constructed by stearamine (SA), representing the rarely explored long-chain aliphatic amine series, to own waterproofness, ultralow noise, and superior optoelectronic performance, which consequently enable a high suitability for UOC. By dimensionality and composition modulations to extend the absorption onset down to 1.5 eV, a broadband response covering the entire transmission window of water (> 1.55 eV) for full- spectrum UOC can be obtained. Besides, featuring a high responsivity of 3.27 A·W−1, a peak external quantum efficiency (EQE) of 630%, fast rise/decay times of 0.35 ms/0.54 ms, a superior detectivity up to 1.35 × 1012 Jones and the capability to distinguish various waveforms and light intensities, the PDs present sensitive and persistent photoresponse underwater. As a result, proof-of-concept wireless transmission of ASCII codes in water is demonstrated.

Aliphatic amines are viable pro-drug moieties in phosphonoamidate drugs

Phosphate and phosphonates containing a single PN bond are frequently used pro-drug motifs to improve cell permeability of these otherwise anionic moieties. Upon entry into the cell, the PN bond is cleaved by phosphoramidases to release the active agent. Here, we apply a novel mono-amidation strategy to our laboratory’s phosphonate-containing glycolysis inhibitor and show that a diverse panel of phosphonoamidates may be rapidly generated for in vitro screening. We show that, in contrast to the canonical l-alanine or benzylamine moieties which have previously been reported as efficacious pro-drug moieties, small and long-chain aliphatic amines demonstrate greater drug release efficacy for our phosphonate inhibitor. These results expand the scope of possible amine pro-drugs that can be used as second pro-drug leave groups for phosphate or phosphonate-containing drugs.

Whole-Cell Photoenzymatic Cascades to Synthesize Long-Chain Aliphatic Amines and Esters from Renewable Fatty Acids.

Long-chain aliphatic amines such as (S,Z)-heptadec-9-en-7-amine and 9-aminoheptadecane were synthesized from ricinoleic acid and oleic acid, respectively, by whole-cell cascade reactions using the combination of an alcohol dehydrogenase (ADH) from Micrococcus luteus, an engineered amine transaminase from Vibrio fluvialis (Vf-ATA), and a photoactivated decarboxylase from Chlorella variabilis NC64A (Cv-FAP) in a one-pot process. In addition, long chain aliphatic esters such as 10-(heptanoyloxy)dec-8-ene and octylnonanoate were prepared from ricinoleic acid and oleic acid, respectively, by using the combination of the ADH, a Baeyer-Villiger monooxygenase variant from Pseudomonas putida KT2440, and the Cv-FAP. The target compounds were produced at rates of up to 37 U g-1 dry cells with conversions up to 90 %. Therefore, this study contributes to the preparation of industrially relevant long-chain aliphatic chiral amines and esters from renewable fatty acid resources.

Solvent Polarity-Dependent Behavior of Aliphatic Thiols and Amines toward Intriguingly Fluorescent AuAgGSH Assembly

Highly stable fluorescent glutathione (GSH)-protected AuAg assembly has been synthesized in water under UV irradiation. The assembly is composed of small Ag2/Ag3 clusters. These clusters gain stability through synergistic interaction with Au(I) present within the assembly. This makes the overall assembly fluorescent. Here, GSH acts as a reducing as well as stabilizing agent. The assembly is so robust that it can be vacuum-dried to solid particles. The as-obtained solid is dispersible in nonaqueous solvents. The interaction between solvent and the assembly provides stability to the assembly, and the assembly shows fluorescence. It is interesting to see that the behavior of long-chain aliphatic thiols or amines toward the fluorescent assembly is altogether a different phenomenon in aqueous and nonaqueous mediums. The assembly gets ruptured in water due to direct interaction with long-chain thiols or amines, whereas in nonaqueous medium, solvation of added thiols or amines becomes pronounced, which hinders the interaction of solvent with the assembly. However, the fluorescence of the assembly is always quenched with thiols or amines no matter what the solvent medium is. In aqueous medium, the fluorescence quenching by aliphatic thiol or amine becomes pronounced with successive decrease in their chain length, whereas in nonaqueous medium, the trend is just reversed with chain length. The reasons behind such an interesting reversal of fluorescence quenching in aqueous and nonaqueous solvents have been discussed explicitly. Again, in organic solvents, thiol or amine-induced quenched fluorescence is selectively recovered by Pb(II) ion without any alteration of excitation and emission maxima. This phenomenon is not observed in water because of the ruptured fluorescent assembly. The fluorescence recovery by Pb(II) and unaltered emission peak only in nonaqueous solvent unequivocally prove the engagement of Pb(II) with thiols or amines, which in turn revert the original solvent-supported stabilization of the assembly.

Surface functionalization of graphene oxide with octadecylamine for improved thermal and mechanical properties in polybutylene succinate nanocomposite

Modification of graphene oxide (GO) with long-chain aliphatic amine offers a substantial improvement in high-performance polymer as nanofiller in the composite. In this work, graphene oxide was functionalized with octadecylamine via sonochemical exfoliation method producing mono- to few-layer graphene oxide/octadecylamine (GOODA) nanofiller. Biodegradable polybutylene succinate (PBS) was incorporated with GOODA via solution intercalation method. GOODA does not profoundly affect the crystallinity of PBS/GOODA nanocomposite, but interestingly improves the mechanical and thermal properties. The addition of only 0.1 wt% GOODA nanofiller loading exhibited a sharp increase in tensile strength and Young’s modulus of up to 50 and 58.9%, respectively. The improvement in strength and thermal behavior could be attributed to the successful interfacial interaction between amine group in GOODA and carboxylic group in PBS chain tail via nucleophilic substitution reaction. This improved interphase structure enhanced the dispersion and exfoliation of GOODA in PBS matrix.

Sphingolipid pathway enzymes modulate cell fate and immune responses.

Sphingolipids (SLs) are a class of essential, bioactive lipids. The SL family includes over 4000 distinct molecules, characterized by their sphingoid base (long-chain aliphatic amine) backbone. SLs are key components of cell membranes, yet their roles go well beyond structure. SLs are involved in many cellular processes including cell differentiation, apoptosis, growth arrest and senescence. As cancer cells routinely display increased growth properties and escape from cell death, it has been suggested that enzymes involved in SL synthesis or catabolism may be altered in cancer cells. In this review, we discuss the role of SL pathway enzymes in cancer, and in acquired resistance to therapy. The use of inhibitors and gene silencing approaches targeting these SL pathways is also explored. Finally, we elaborate on the role of SL pathway enzymes in the tumor microenvironment and their effect on immune cell function.

In situ modification of membrane elements for improved boron rejection in RO desalination

The study presents in situ modification of a spiral-wound seawater reverse osmosis (SWRO) membrane elements using sorption of hydrophobic long-chain aliphatic amine molecules as a generic approach to increasing selectivity, in particular, boron removal. Spiral-wound seawater SW30 elements modified using decylamine and dodecylamine showed 2–4 times lower boron passage for the modified elements at the expense of a moderate drop in permeability. Autopsy indicated no change in surface morphology and chemistry, suggesting immobilization of the modifying molecules within the active layer. Overall, the reported in situ modification of the SWRO element resulted in a superior trade-off between permeability and boron passage and no change in salt rejection, as compared to regular polyamide membranes. The enhanced selectivity toward boron5 removal could potentially help eliminate or reduce the costs related to the second pass in sea water desalination.

Fluorescence enhancement via varied long-chain thiol stabilized gold nanoparticles: A study of far-field effect

Metal enhanced fluorescence of carbon dots has been reported in aqueous solution. Moderately fluorescing carbon dots (λex=360nm and λem=440nm) of 6–8nm diameters (CDA) have been synthesized from freshly prepared aqueous ascorbic acid solution under modified hydrothermal treatment. The CDA fluorescence is quenched at the close proximity with gold nanoparticles (AuNPs). Here, a substrate specific near-field electric field distribution is pronounced. Anticipating distance dependent fluorescence enhancement phenomenon, long-chain aliphatic thiol capped AuNPs are introduced to improve fluorescence of moderately fluorescing CDAs. The long-chain aliphatic thiols act as spacers between CDA and AuNP. Interestingly, the fluorescence of CDA is observed to be enhanced successively as the chain lengths of aliphatic thiols are increased. Fluorescing CDA, upon excitation, transfers energy to the nearby AuNP and a plasmon is induced. This plasmon radiates in the far-field resulting in fluorescence enhancement of CDAs. Such an interesting enhancement in emission with metallic gold is termed as gold enhanced fluorescence. This far-field effect for fluorescence enhancement of CDA particles becomes a general consensus in solution with varied long-chain aliphatic amine ligand capped silver nanoparticles (AgNPs). Finally, consequence of far-field effect of fluorescence enhancement has been observed while derivatized AuNP and AgNP are introduced into the CDA solution simultaneously which is described as reinforced fluorescence enhancement due to coupled plasmonic radiation.

Chemical Functionalization of Inner Walls of Carbon Nanotubes with Long-Chain Aliphatic Amines

In this work, we will explore the possibility of solvent-free functionalization of inner surfaces of (CNTs) with amines of different structure. This method can generate CNTs useful for many applications especially, molecules transport properties of CNT membranes and drug delivery using liberated CNTs. The structural and chemical composition of the functionalized CNTs was analyzed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR), which confirm successful and specific inner functionalization of CNTs.

Synthesis and antimicrobial properties of lipophilic Schiff base copper and palladium complexes

The reaction of Cu(II) sulfate or Pd(II) acetate with four salicylaldimines derived from 5-bromosalicylaldehyde and long-chain aliphatic primary amines afforded the corresponding metal complexes 2a–d and 3a–d, respectively. All complexes were characterized by physicochemical and spectroscopic methods. The molecular structure of 2b was determined by a single-crystal X-ray diffraction study. All complexes were tested for their potential antifungal and antibacterial activities.

A carbon nanotube/poly [Ni-(Protoporphyrin IX)] composite for amperometric detection of long chain aliphatic amines

Poly [Ni-Protoporphyrin] film (pNiPP), containing multiwall carbon nanotubes (MWCNT) was used to cover a glassy carbon electrode. The hybrid material (pNiPP/MWCNT) successfully combines the permselectivity of pNiPP with the high conductivity of MWCNT.The modified electrode was used to perform amperometric detection of long chain aliphatic amines (LCAA) in order to prevent the passivation effect of the aliphatic chain. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) demonstrated that the pNiPP/MWCNT facilitates the electron transfer reaction. The charge transfer resistance (Rct) values were significantly lower by up to one order of magnitude compared to the bare electrode. Differential pulse polarography (DPP) showed a marked decrease of the overpotential generated by the aliphatic chain. The calibration of the amperometric peak area vs. concentrations of derivatized LCAA exhibits a linear response within the range of 0.018 and 28μM and correlation coefficient (R2) higher than 0.999 (n=5). The quantitation limit of the pNiPP/MWCNT electrode is about 400 times lower than the UV–visible detection. RSD of 7.2%, 5.8%, 2.5% and 2.3% was obtained for concentrations of 0.028, 0.28, 2.8 and 28μM of ferrocenyl octadecylamine. A solution of sphingosine, 0.23μM, was exclusively detected with HPLC-ECD with pNiPP/MWCNT electrode.

Esterification and amidation for grafting long aliphatic chains on to cellulose nanocrystals: a comparative study

Heterogeneous modification of cellulose nanocrystals (CNC) has been achieved by using esterification and amidification to attach long aliphatic chains. Long-chain aliphatic acid chlorides and amines were used as grafting reagents. Surface grafting with acyl chains was confirmed by Fourier-transform infrared spectroscopy, elemental analysis, and X-ray photoelectron spectroscopy. It was found that the degree of substitution (DS) of the surface is highly dependent on the method of modification. Irrespective of grafting approach, the modified CNC was found to be hydrophobic after modification, as attested by contact angle measurement. The main emphasis was on the correlation between DS and the extent of surface grafting.

Anti-mycobacterial activities of copper(II) salicylaldimine complexes derived from long-chain aliphatic amines

Twelve copper(II) Schiff base complexes derived from lipophilic amines have been prepared using either salicylaldehyde or ortho-vanillin via a microwave-assisted reaction. All complexes have been obtained elementally pure and an X-ray diffraction of an isopentyl derivative has confirmed the structure of these compounds. All complexes showed a promising degree of anti-mycobacterial activity against Mycobacterium tuberculosis, where activity seemed to increase with an increase in the length of the aliphatic chain.

Synthesis and antibacterial activity of new long-chain-alkyl bile acid-based amphiphiles

The efficient synthesis of some bile acid-derived cationic amphiphiles with a flexible long hydrocarbon tail was investigated. Firstly, the modification on the side-chain carboxyl of bile acids was carried out efficiently by one-pot amidation of bile acids and a long-chain aliphatic amine in the presence of HOBt and DCC to introduce a flexible long hydrocarbon tail. Then the hydrophilic concave side of bile acids with hydroxyl groups was further modified into cationic groups for strengthening hydrophilicity. This strategy offered a very straightforward and efficient method for access to the designed amphiphiles in good overall yields. The preliminary results showed that an increase both in the length of the hydrophobic tail and in the number of charged groups resulted in a decrease in the CMC of bile acid-derived cationic amphiphiles. And the bile acid-derived cationic amphiphiles with a flexible longer hydrocarbon tail and more positive charges had the highest antibacterial and antimicrobial activity.

Antifungal activity of silver nanoparticle-encapsulated β-cyclodextrin against human opportunistic pathogens

Silver nanoparticles were synthesised by reducing silver acetate with a long-chain aliphatic amine. β-Cyclodextrin (CD)-stabilised silver nanoparticles were successfully synthesised and characterised by the UV–vis spectroscopy and scanning electron microscopy analysis. This system was examined for their antifungal activity against opportunistic human pathogens such as Aspergillus fumigatus, Mucor ramosissimus and Chrysosporium species. This study clearly demonstrates that the present system is a powerful antifungal agent against human opportunistic pathogenic fungi.