Examining metal nanoparticle surface chemistry using hollow-core, photonic-crystal, fiber-assisted SERS

In this Letter, we demonstrate the efficacy of hollow core photonic crystal fibers (HCPCFs) as a surface-enhanced Raman spectroscopy (SERS) platform for investigating the ligand exchange process on the surface of gold nanoparticles. Raman measurements carried out using this platform show the capability to monitor minute amounts of surface ligands on gold nanoparticles used as an SERS substrate. The SERS signal from an HCPCF exhibits a tenfold enhancement compared to that in a direct sampling scheme using a cuvette. Using exchange of cytotoxic cetyltrimethylammonium bromide with α-methoxy-ω-mercaptopoly(ethylene glycol) on the surface of gold nanorods as an exemplary system, we show the feasibility of using HCPCF SERS to monitor the change in surface chemistry of nanoparticles.     

Two new XP(O)[NHC(CH3)3]2 phosphoramidates,with X = (CH3)2N and [(CH3)3CNH]2P(O)(O)

In N,N′‐di‐tert‐butyl‐N′′,N′′‐dimethylphosphoric triamide, C₁₀H₂₆N₃OP, (I), and N,N′,N′′,N′′′‐tetra‐tert‐butoxybis(phosphonic diamide), C₁₆H₄₀N₄O₃P₂, (II), the extended structures are mediated by P(O)...(H—N)₂ interactions. The asymmetric unit of (I) consists of six independent molecules which aggregate through P(O)...(H—N)₂ hydrogen bonds, giving R₂¹(6) loops and forming two independent chains parallel to the a axis. Of the 12 independent tert‐butyl groups, five are disordered over two different positions with occupancies ranging from to . In the structure of (II), the asymmetric unit contains one molecule. P(O)...(H—N)₂ hydrogen bonds give S(6) and R₂²(8) rings, and the molecules form extended chains parallel to the c axis. The structures of (I) and (II), along with similar structures having (N)P(O)(NH)₂ and (NH)₂P(O)(O)P(O)(NH)₂ skeletons extracted from the Cambridge Structural Database, are used to compare hydrogen‐bond patterns in these families of phosphoramidates. The strengths of P(O)[...H—N]_x (x = 1, 2 or 3) hydrogen bonds are also analysed, using these compounds and previously reported structures with (N)₂P(O)(NH) and P(O)(NH)₃ fragments.     

Microfluidic synthesis of chitosan-based nanoparticles for fuel cell applications

A microfluidic platform is developed for the synthesis of monodisperse, 100 nm, chitosan based nanoparticles using nanogelation with ATP. The resulting nanoparticles tuned and enhanced transport and electrochemical properties of Nafion based nanocomposite membranes, which is highly favorable for fuel cell applications.     

‘Click Synthesis’ of Some Novel O‐Substituted Oximes Containing 1,2,3‐Triazole‐1,4‐diyl Residues as New Analogs of β‐Adrenoceptor Antagonists

The ‘click synthesis’ of some novel O‐substituted oximes, 7a – 7t , which contain 1,2,3‐triazolediyl residues, as new analogs of β‐adrenoceptor antagonists is described (Schemes 1–4). The synthesis of these compounds was achieved in four to five steps. The formation of oximes of 9H‐fluoren‐9‐one and benzophenone, i.e., 9a and 9b , respectively, followed by their reaction with propargyl bromide, afforded O‐propargyl oximes 10a and 10b , respectively, which by a subsequent CuI‐catalyzed Huisgen cycloaddition with prepared β‐azido alcohols 11a – 11j (Schemes 2 and 3), led to the target compounds 7a – 7t in good yields.     

Oxidative addition of MeI to some cyclometalated organoplatinum(II) complexes: Kinetics and mechanism

New cyclometalated platinum(II) complexes [PtMe(C^N)L], 1, in which C^N = deprotonated 2-phenylpyridine (ppy), benzo[h]quinoline (bhq) or 2-(p-tolyl)pyridine (tpy) and L = PPh₃ or PMePh₂, were synthesized by the reaction of [PtMe(C^N)(SMe₂)] with 1 equiv of L. The reaction of complexes 1 with MeI gave the cyclometalated Pt(IV) complexes [PtMe₂I(C^N)L], 3. On the basis of kinetic studies, using Uv–visible spectroscopy, it was suggested that the latter oxidative addition reactions were proceeded by an S_N2 mechanism. The rates of the reactions at different temperatures were measured and consistent with the proposed mechanism, large negative ΔS³ values were found for each reaction. Besides, rate of reactions (in CHCl₃) involving the PPh₃ complexes [PtMe(C^N)(PPh₃)], were almost 3–5 times slower than those involving the PMePh₂ complexes [PtMe(C^N)(PMePh₂)]. This was attributed to the electronic and steric effects of PPh₃ ligand as compared with that of PMePh₂ ligand which was further confirmed using density functional theory (DFT) calculations through finding approximate structures for the described complexes.     

A Facile One‐Pot Synthesis of Substituted Quinolines via New Multicomponent Reaction

An efficient synthesis of quinoline derivatives is described via the reaction between ethyl chloropyruvate or alkyl 4‐chloroacetoacetate and activated acetylenic compounds in the presence of nucleophilic form of isatin in water as the solvent. Nucleophilic form of isatin is produced from the reaction of isatin and triethylamin.     

Microwave-enhanced synthesis of aryl nitriles using dimeric orthopalladated complex of tribenzylamine and K4[Fe(CN)6]

The activity of palladacycle [Pd{C₆H₄(CH₂N(CH₂Ph)₂)} (μ-Br)]₂ complex was investigated in the synthesis of benzonitriles under both conventional and microwave irradiation conditions and their results were compared together. This complex is an efficient, stable, and non-sensitive to air and moisture catalyst for the cyanation reaction. The substituted benzonitriles were produced of various aryl halides in excellent yields and short reaction times using a catalytic amount of [Pd{C₆H₄(CH₂N(CH₂Ph)₂)} (μ-Br)]₂ complex and K₄[Fe(CN)₆] in DMF at 130 °C. In comparison to conventional heating conditions, the reactions under microwave irradiation gave higher yields in shorter reaction times.     

Copper-catalyzed one-pot synthesis of tetrasubstituted pyrazoles from sulfonyl azides,terminal alkynes,and hydrazonoyl chlorides

Ketenimine intermediates generated by the addition of copper acetylides to sulfonyl azides are trapped by nitrile imines (generated from hydrazonoyl chlorides and triethylamine) to afford tetrasubstituted pyrazoles in moderate to good yields.     

Molecular Modeling Study of Drug-DNA Combined to Single Walled Carbon Nanotube

One of the applications of nanotechnology is use of carbon nanotubes for the targeted delivery of drug molecules. To demonstrate the physical and chemical properties of biomolecules and identify new material of drug properties, the interaction of carbon nanotubes (CNTs) with biomolecules is a subject of many investigations. CNTs is a synthetic compound with extraordinary mechanical, thermal, electrical, optical, and chemical properties widely applied for technological purposes. In this article we have tried to investigate thermodynamic parameters and dielectric effects in different solvents for one of the most famous anticancer drug ??cisplatin?? combined to SWCNT, by Monte Carlo and density functional theory (DFT) calculations. Cause of platinum element in cisplatin we have done calculations as Gibbs free energy, thermal enthalpy, thermal energy and entropy at 6-31G** basis set with SCRF model of solvent. In this work, the major point has been embedded that results of both two methods of Monte Carlo and DFT can overlap with each other and cisplatin- SWCNT is a suitable compound for drug delivery in different media.