N,N,N-Trimethylchitosan chloride as a gene vector: synthesis and application

N,N,N-Trimethylchitosan chloride with different degrees of quaternization has been synthesized and characterized by (1)H NMR spectroscopy. The particle size ranges from 150 to 600 nm, which is dependent on the N/P ratio and is less influenced by the degree of quaternization. The majority of the particles have a spherical morphology. The zeta potential of the particles increases with the N/P ratio and the quaternization degree of TMC. Short-term contact experiments show good biocompatibility of TMC, but long-term contact experiments reveal its high toxicity. This study suggests that TMC is a promising gene carrier, but further modification is still required to improve its cytocompatibility.     

Flow Injection Analysis of Benzoyl Peroxide Using N,N,N,N-Tetramethyl-p-phenylenediamine (TMPDA) and Surfactants

Abstract

The flow injection analysis of benzoyl peroxide using N,N,N,N-tetramethyl-p-phenylenediamine (TMPDA, also known as Wurster's reagent) and a solvent system including the surfactant sodium dodecyl sulfate (SDS) and cerium(IV) as a catalyst at pH 6.0 at 612 nm was investigated. The method was applied to the analysis of acne cream and flour. The study included a 26-metal-ion search for other possible methods of catalysis and a buffer study of SDS and cetyltrimethyl ammonium bromide (CTAB).     

N, N, N′, N′-四丁基丙二酰胺萃取镧系元素的性能及机理

研究新型萃取剂从硝酸盐介质中萃取分离稀土元素对于后处理工艺具有重要意义。本文报道以甲苯为稀释剂,N,N,N′,N′-四丁基丙二酰胺(TBMA)从硝酸盐介质中萃取铈(Ⅲ)、镝(Ⅲ)、铒(Ⅲ)、镨(Ⅲ)、钐(Ⅲ)、铽(Ⅲ)、铥(Ⅲ)、镱(Ⅲ)的机理。考察了硝酸浓度、TBMA浓度、盐析剂浓度以及温度对上述三价镧系离子分配比的影响。得出萃合物的组成主要是三配体配合物M(NO₃)₃·3TBMA;计算出萃取反应的条件平衡常数、萃取平衡常数。温度效应研究表明萃取反应主要是焓驱动的。对萃取分离系数以及TBMA萃取三价镧系离子的规律进行了初步研究。     

Synthesis,Structure and Cytotoxicity of N,N and N,O-Coordinated RuII Complexes of 3-Aminobenzoate Schiff Bases against Triple-negative Breast Cancer

Half-sandwich Ru^II complexes, [(YZ)Ru^II(η⁶-arene)(X)]+, (YZ=chelating bidentate ligand, X=halide), with N,N and N,O coordination ( 1 – 9 ) show significant antiproliferative activity against the metastatic triple-negative breast carcinoma (MDA-MB-231). 3-aminobenzoic acid or its methyl ester is used in all the ligands while varying the aldehyde for N,N and N,O coordination. In the N,N coordinated complex the coordinated halide(X) is varied for enhancing stability in solution (X=Cl, I). Rapid aquation and halide exchange of the pyridine analogues, 2 and 3 , in solution are a major bane towards their antiproliferative activity. Presence of free −COOH group ( 1 and 4) make complexes hydrophilic and reduces toxicity. The imidazolyl 3-aminobenzoate based N,N coordinated 5 and 6 display better solution stability and efficient antiproliferative activity (IC₅₀ ca. 2.3–2.5 μM) compared to the pyridine based 2 and 3 (IC₅₀>100 μM) or the N,O coordinated complexes ( 7 – 9 ) (IC₅₀ ca. 7–10 μM). The iodido coordinated, 6 , is resistant towards aquation and halide exchange. The N,O coordinated 7 – 9 underwent instantaneous aquation at pH 7.4 generating monoaquated complexes stable for at least 6 h. Complexes 5 and 6 , bind to 9-ethylguanine (9-EtG) showing propensity to interact with DNA bases. The complexes may kill via apoptosis as displayed from the study of 8 . The change in coordination mode and the aldehyde affected the solution stability, antiproliferative activity and mechanistic pathways. The N,N coordinated ( 5 and 6 ) exhibit arrest in the G2/M phase while the N,O coordinated 8 showed arrest in the G0/G1 phase.     

Screening of N,N‐bidentate and N,N,N‐tridentate pyridine‐based ligands in the catalytic allylic oxidation of cyclic olefins

A variety of chiral N,N‐bidentate and N,N,N‐tridentate ligands based on the pyridine framework, namely C2‐symmetric dipyridylmethane and terpyridine, N‐(p‐toluensulfinyl)iminopyridines and two kinds of iminopyridines, has been assessed in the asymmetric copper(I)‐catalysed allylic oxidation of cyclic olefins. Catalytic activity and enantioselectivity were found to be highly dependent upon the framework of the ligands, which afforded cycloalkenyl benzoates in low to moderate yields and enantioselectivities. The best yields (up to 70%) and enantioselectivities (up to 53% enantiomeric excess) were obtained with an iminopyridine based on camphane and quinoline skeletons. Copyright © 2014 John Wiley & Sons, Ltd.     

A Theoretical Approach to the Description of the Thermal Dissociation of N,N,N-Trimethylmethanaminium Halides

MNDO/d and PM3 quantum chemistry methods were used to examine reaction pathways and predict thermodynamic and kinetic barriers for the thermal dissociation of isolated conglomerates of N,N,N-trimethylmethanaminium cations (TMA⁺) and halide anions (X = Cl⁻, Br⁻ and I⁻). Theoretically obtained changes in enthalpy and entropy for the above-mentioned process were subsequently supplemented with theoretically determined crystal lattice energies, that enabled prediction of relevant characteristics for the dissociation of crystalline phases. Data thus obtained compare only qualitatively with those available in literature and resulting predominantly from thermoanalytical investigations, although values of theoretical characteristics generally follow the same trends as experimental ones. This revised version was published online in August 2006 with corrections to the Cover Date.     

EFFECT OF N,N,N~'''',N~''''-TETRAALKYL TEREPHTHALAMIDE ON NON-ISOTHERMAL CRYSTALLIZATION KINETICS OF POLYPROPYLENE

The effect of N,N,N',N'-tetraalkyl terephthalamide (TATA) on the non-isothermal crystallization and melting characteristics of polypropylene (PP) was studied. The addition of TATA can lead to the formation of β-crystal PP. With the increase in TATA concentration the degree of crystallinity for β-crystal PP increased significantly, and that for α-crystal PP decreased, which indicated that TATA effectively induced the formation of β-crystal PP. WAXD also revealed the existence of β-crystal PP after the introduction of TATA into PP. PP containing TATA crystallized at a temperature range of 5-10℃ higher than that of pure PP, and the half-crystallization time (t1/2) and Avrami exponent (n) of PP at the same cooling rate were decreased by the addition of TATA, indicating that TATA influenced the crystallization rate and crystallization growth mode of PP. The rate constant of crystallization of PP containing TATA (Zc) was larger than that of pure PP, which further indicated that the crystallization of PP was accelerated by the addition of TATA.     

Capillary electrophoresis in N,N-dimethylformamide

N,N-Dimethylformamide (DMF) is a dipolar protophilic solvent with physicochemical properties that makes it suitable as solvent for capillary electrophoresis (CE). It is prerequisite for the proper application of CE to adjust and to change the pH of the background electrolyte (BGE) in a defined manner. This was done in the present work using benzoic acid-benzoate by selecting different concentration ratios of acid and salt, and calculating the theoretical pH from the activity-corrected Henderson-Hasselbalch equation. The mobilities of the analytes (chloro- and nitro-substituted phenolates) were found to follow reasonably well the typical sigmoid mobility versus pH curve as predicted by theory. The actual mobilities and pK(a) values (at 25 degrees C) of the analytes were derived from these curves. pK(a) values were in the range of 11.1-11.7, being thus 3-4.4 units higher than in water. This pK(a) shift is caused by the destabilization of the analyte anion and the better stability (solubility) of the molecular analyte acid in DMF, which overcome the higher basicity of DMF compared to water. Absolute mobilities were calculated from the actual mobilities; they were between 32x10(-9) and 42x10(-9) m(2)/Vxs. Slight deviations of the measured mobilities from the theoretical mobility versus pH curve were discussed on the bases of ion pairing and heteroconjugation and homoconjugation of either buffer components or buffer components and analytes. Heteroconjugation was used as a mechanism for the electrically driven separation of neutral analyte molecules in a BGE where salicylate acted as complex forming ion. Rough estimation of the complexation constants for the phenolic analytes gave values in the range of 100-200 L/mol. Addition of water to the solvent decreased the effect of heteroconjugation, but it was still present up to the surprisingly high concentration of 20% water. Electrophoretically relevant parameters like ionic mobilities and pK(a) values, and conjugation and ion pairing are dependent on the water content of the solvent. The water uptake of DMF was measured when exposed to humidity of ambient air. The resulted behavior of the water uptake was found rather similar to that for acetonitrile and methanol.     

N,N-Dimethylcarbamato-Komplexe von Kupfer und Zink

N,N -Dimethylcarbamato Complexes of Copper and Zinc Reactions of the 1 : 1 adduct of dimethylamine and carbon dioxide (dimcarb) with metallic copper and zinc, respectively, are reported. Dimcarb gives with copper in the presence of oxygen the N,N-dimethylcarbamato copper(II) complex [Cu(O₂CNMe₂)₂(HNMe₂)₂] ( 1 ). Zinc spontaneously dissolves in a dimcarb-acetonitrile mixture under generation of hydrogen and giving (H₂NMe₂)[Zn₂(O₂CNMe₂)₅] · MeCN ( 3 ). The rate of this reaction is strongly depending on the purity of the metal, high purity zinc doesn't react. But 3 can be prepared from it by electrosynthesis. The crystal structures of 1 and 3 were determined by X-ray analysis. In 1 the copper atom has a distorted octahedral coordination sphere in which the two carbamate ligands are chelating. In the homoleptic complex anion of 3 two zinc atoms are bridged by three carbamate ligands whereas the other two carbamate ligands are coordinated monodentately.     

NaBH4-I2还原法制备N,N'-二甲基间苯二胺

以间苯二胺为原料, 与酰化剂甲酸反应制得中间体N,N'-二甲酰基间苯二胺, 再以NABH4-I2为还原剂合成得到产品N,N'-二甲基间苯二胺, 对合成工艺进行了优化, 并分析了还原机理, 化合物的结构经IR, 1H NMR和MS分析确定. 该法原料易得, 反应条件要求低, 收率高且成本更低.     

Amidation and esterification of carboxylic acids with amines and phenols by N,N′-diisopropylcarbodiimide: A new approach for amide and ester bond formation in water

The present study reports the successful synthesis of two important and abundant functional groups "ester and amide" by N,N′-diisopropylcarbodiimide (DIC) in water as a green solvent. A wide range of substrates could be employed with high functional group tolerance. The products were obtained in high yields after short reaction times. This method provides an efficient, economic, simple and very mild protocol for ester and amide bond formation in aqueous media. In addition, this work not only may lead to environmentally benign systems but also will provide a new aspect of organic chemistry in water.     

N,N-二取代甘氨酸酯的合成及其经皮促渗活性

合成了4个新的N,N-二取代甘氨酸酯,其结构经^1HNMR谱、IR谱、MS-ESI谱和元素分析确证。在改良的Franz扩散池上,用离体裸鼠皮作生物膜,扑热息痛或消炎痛作药物模型进行经皮促渗活性对比试验。结果显示：N,N-二甲基甘氨酸-（E）-3,7-二甲基-2,6-辛二烯酯（2a）具有出色的促透活性,含2．5％的2a促进扑热息痛、消炎痛经皮渗透的效果分别是Azone的2．1和2．6倍,且时滞缩短,超过DDAA的经皮促渗活性;而N,N-二甲基甘氨酸-6-戊氧基-1-己酯（2b）的经皮促渗活性接近Azone,且时滞更短。     

Stable N,N’-Diarylated Dihydrodiazaacene Radical Cations

Three stable N,N’-diarylated dihydroazaacene radical cations were prepared by oxidation of neutral N,N’-diarylated dihydroazaacenes synthesized via palladium-catalyzed Buchwald-Hartwig aminations of aryl iodides with N,N’-dihydroazaacenes. Both neutral as well as oxidized species were investigated via UV-vis spectroscopy, single crystal analysis, and DFT calculations. All the radical cations are surprisingly stable—their absorption spectra in dichloromethane remain unchanged in ambient conditions for at least 24 hours.     

Iron(II) complexes with bio-inspired N,N,O ligands as oxidation catalysts: olefin epoxidation and cis-dihydroxylation

The Rieske dioxygenases are a group of non-heme iron enzymes, which catalyze the stereospecific cis-dihydroxylation of its substrates. Herein, we report the iron(II) coordination chemistry of the ligands 3,3-bis(1-methylimidazol-2-yl)propionate (L1) and its neutral propyl ester analogue propyl 3,3-bis(1-methylimidazol-2-yl)propionate (PrL1). The molecular structures of two iron(II) complexes with PrL1 were determined and two different coordination modes of the ligand were observed. In [Fe(II)(PrL1)(2)](BPh(4))(2) (3) the ligand is facially coordinated to the metal with an N,N,O donor set, whereas in [Fe(II)(PrL1)(2)(MeOH)(2)](OTf)(2) (4) a bidentate N,N binding mode is found. In 4, the solvent molecules are in a cis arrangement with respect to each other. Complex 4 is a close structural mimic of the crystallographically characterized non-heme iron(II) enzyme apocarotenoid-15-15'-oxygenase (APO). The mechanistic features of APO are thought to be similar to those of the Rieske oxygenases, the original inspiration for this work. The non-heme iron complexes [Fe(II)(PrL1)(2)](OTf)(2) (2) and [Fe(II)(PrL1)(2)](BPh(4))(2) (3) were tested in olefin oxidation reactions with H(2)O(2) as the terminal oxidant. Whereas 2 was an active catalyst and both epoxide and cis-dihydroxylation products were observed, 3 showed negligible activity under the same conditions, illustrating the importance of the anion in the reaction.     

N,N,N,N-四乙酰氧甲基-1,5-二苯基-2,4,6,8-四氮杂双环[3.3.0]-3,7-辛二酮的合成及晶体结构研究

以苯基苷脲为原料设计合成N,N,N,N-四乙酰氧甲基-1,5-二苯基-2,4,6,8-四氮杂双环[3.3.0]-3,7-辛二酮,并对其结构进行了X-单晶衍射表征.结果表明:该化合物晶体属于单斜晶系,空间群,P_(21/n),a=1.102 3(7)nm,b=1.741 3(11)nm,c=1.261 2(8)nm,α=90°,β=99.601(17)°,γ=90°,V=2.386 88 nm~3,Z=4,R(1)=0.075 9.量子化学计算结果表明,化合物的偶极矩为1.530×10~(-29) C·m.     

Structurally Modelling the 2-His-1-Carboxylate Facial Triad with a Bulky N,N,O Phenolate Ligand

We present the synthesis and coordination chemistry of a bulky, tripodal N,N,O ligand, Im^Ph2NNO ^{t Bu} ( L ), designed to model the 2-His-1-carboxylate facial triad (2H1C) by means of two imidazole groups and an anionic 2,4-di-tert-butyl-subtituted phenolate. Reacting K-L with MCl₂ (M = Fe, Zn) affords the isostructural, tetrahedral non-heme complexes [Fe(L)(Cl)] ( 1 ) and [Zn(L)(Cl)] ( 2 ) in high yield. The tridentate N,N,O ligand coordination observed in their X-ray crystal structures remains intact and well-defined in MeCN and CH₂Cl₂ solution. Reacting 2 with NaSPh affords a tetrahedral zinc thiolate complex, [Zn(L)(SPh)] ( 4 ), that is relevant to isopenicillin N synthase (IPNS) biomimicry. Cyclic voltammetry studies demonstrate the ligand's redox non-innocence, where phenolate oxidation is the first electrochemical response observed in K-L , 2 and 4 . However, the first electrochemical oxidation in 1 is iron-centred, the assignment of which is supported by DFT calculations. Overall, Im^Ph2NNO ^{t Bu} provides access to well-defined mononuclear, monoligated, N,N,O-bound metal complexes, enabling more accurate structural modelling of the 2H1C to be achieved.     

Improved Synthesis of N,N′‐Disuccinimidyl Carbonate using α‐Pinene as Acid Scavenger

An improved synthesis of N,N′‐disuccinimidyl carbonate (DSC) is described where α‐pinene is utilized as an efficient scavenger of HCl liberated during the reaction of N‐hydroxysuccinimide with triphosgene in THF. The α‐pinene hydrochloride formed is soluble in THF and gives very pure DSC in good yields.     

Stable Radical Cations of N,N′-Diarylated Dihydrodiazapentacenes

A series of quinoidal N,N′-diaryldiaza-N,N′-dihydropentacenes (Quino) was prepared in a two-step reaction, starting from quinacridone. Oxidation of Quino furnishes stable radical cations, isoelectronic to the radical anions of the azaacenes, whereas the dicationic species are isoelectronic to neutral azapentacenes. The spectroscopic properties of the diaryldiazapentacenes and their oxidized mono- and dications are equivalent to that of the dianion of tetraazapentacene (TAP), its radical anion and the neutral TAP.     

Theoretical study on structures and stabilities of [H,Ge,C,N

Theoretical investigations are performed for the first time on the simplest hydrogenated germanium cyanide [H,Ge,C,N], whose analogs [H,C(2),N] and [H,Si,C,N] have been detected in space and laboratory, respectively. The detailed potential energy surfaces in both singlet and triplet states are constructed at the CCSD(T)/6-311+G(3df,2p)//B3LYP/6-31G(d)+ZPVE level, including 18 minimum isomers and 26 interconversion transition states. The former three low-lying and kinetically stabilized isomers are HGeCN (1)1 (0.0 kcal/mol), HGeNC (1)2 (5.1 kcal/mol), and cyclic cCHNGe(1)7 (11.1 kcal/mol). In addition, five isomers HCNGe (1)3 (33.8), HNCGe (1)5 (29.8), cNHCGe (1)8 (37.9), HGeCN (3)1 (30.1), and HNCGe (3)5 (26.5) each have considerable barriers, despite their high energies. Future laboratory characterization and astrophysical detection of the eight [H,Ge,C,N] isomers, especially the former three low-lying species (1)1, (1)2, and (1)7, are highly recommended. The accurate spectroscopic data at the QCISD/6-311G(d,p) level are provided. For some species, the CBS-QB3 calculations are also performed. Wherever possible, comparisons with the analogous [H,C(2),N] and [H,Si,C,N] are made on the structural, energetic, and bonding properties.