Vibrational spectroscopic and conformational studies of 1-(4-pyridyl)piperazine

Possible stable conformers of the 1-(4-pyridyl)piperazine (1-4pypp) molecule were experimentally and theoretically studied by FT-IR and Raman spectroscopy. FT-IR and Raman spectra were recorded in the region of 4000–200 cm⁻¹. Optimized geometric structures related to the minimum on the potential energy surface were investigated by the B3LYP hybrid density functional theory method using the 6-31G(d) basis set. Comparison of the experimental and theoretical results indicates that the density functional B3LYP method provides satisfactory results for the prediction of vibrational wavenumbers and structural parameters and equatorial-equatorial (e-e) isomer is supposed to be the most stable form of the 1–4pypp molecule.     

Antimalarials. 15. Side-chain analogues of 8-(4-amino-1-methylbutylamino)-6-methoxy-4-methyl-5-(3-trifluoromethylphenoxy)quinoline

Six side chain analogs of the highly active antimalarial agent 8-(4-amino-1-methylbutylamino)-6-methoxy-4-methyl-5-(3-trifluoromethylphenoxy)quinoline (I) were prepared and evaluated for blood and tissue schizonticidal activity. Although most examples were markedly superior to primaquine none was superior to the parent compound I.     

Bis-(8-oxo quinoline)diorgano tellurium(IV) compounds; structural and spectroscopic studies

Three new compounds of the type R₂Te(OR′)₂ are reported in which R′ bears a potentially co-ordinating group: bis-(8-hydroxo quinoline)dimethyltellurium (I) bis-(8-oxo-2-methyl quinoline)dimethyltellurium (II), and bis-(8-oxo-quinoline) di-(p-tolyl)tellurium (III). The crystal structures of II and III have been determined. The primary geometry around tellurium in both cases can be described as ψ-trigonal bipyramidal but long Te N contacts in the range 2.840(6)–2.899(4) Å which lie well within the van der Waals distance imply extension of the co-ordination sphere. Variable temperature multi-nuclear (¹ H, ¹³C, ¹²⁵Te) studies of the compounds I, II, and III in solution indicate the presence of a single species over the range 216–343 K. The data do not distinguish between the presence of a single 14-Te-6 pertellurane seen in the crystallographic studies, or that of such a species in equilibrium, rapid on the ¹H and ¹²⁵Te timescales, with the 10-Te-4 tellurane.     

IR spectroscopic studies on substituted pyridine N-oxide complexes of tin(IV) chloride in acetonitrile

Complexes of eleven substituted pyridine N-oxide donors with stannic chloride in acetonitrile solution were investigated ultizing IR spectroscopy. Two distinct types of behaviour were noted: (1) Pyridine N-oxide donors containing electron releasing substituents generally form strong complexes with SnCl₄ and exhibit maxima in continuous variation plots at a 2:1 ligand-to-metal ratio. Little or no free ligand is detected in these solutions until this ratio is exceeded. Ligands exhibiting this behaviour include the 2-methyl-, 3-methyl-, 4-methyl-, 4-methoxy- and 4-phenylpyridine N-oxides.(2) Pyridine N-oxide donors containing electron neutral to electron with-drawing substituents generally form weaker complexes with SnCl₄ aM exhibit maxima in continuous variation plots at a 1:1 ligand-to-metal ratio. Free ligand is evident in these solutions even at ligand-to-metal ratios as low as 1:3. Formation plots for these complexes indicate the possibility that 1: 2 and 1:1 ligand to metal complexes exist in the concentration ranges studied. Ligands exhibiting this behaviour include the 4-chloro-, 4-nitro-, 3 and 4-acetyl-pyridine N-oxides and 2-pyridine methanol N-oxide.The complex of 2,6-1utidine N-oxide with SnCl₄ exhibits behaviour characteristic of the 1:1 complexes even though the substituents are electron releasing. This ligand contains the most sterically crowded N-O group in the series, however, and steric factors are invoked to explain this behavior.These results are rationalized in terms of an equilibrium model which includes the postulated existence of oxygen bridged dimers comprising a dominant species in solutions containing the 1:1 complexes. Some supporting ¹H NMR and polarographic data are also presented and discussed.     

新试剂5-(对羧基苯偶氮)-8-羟基喹哪啶与铂(Ⅳ)显色反应的研究及应用

合成了新试剂5-(对羧基苯偶氮)-8-羟基喹哪啶(5-CPAHQD),并用分光光度法研究了其与铂(Ⅳ)的显色反应。结果表明,在pH=2.0~3.05的HCl—邻苯二甲酸氢钾缓冲溶液中,在乳化剂OP的存在下,试剂与铂(Ⅳ)形成1∶1的稳定红色络合物。建立了测定铂的光度法新体系,其最大吸收波长λmax=490nm,表观摩尔吸光系数ε=5.80×105L.mol-1.cm-1。铂(Ⅳ)的质量浓度在0.02~0.32μg/mL内符合比尔定律。方法用于测定美国蜂窝废催化剂中的铂,结果与原子吸收法相符,平行测定5次的RSD在0.75%~2.38%之间。     

Voltammetric and spectroscopic studies of the interaction between copper (II) ions with the pesticide carbendazim and its effect in the soil

Journal of Solid State Electrochemistry - The pesticide carbendazim (MBC) has nitrogen and oxygen in their structure which can interact with metal ions. This work evaluated the interaction between...     

Preparation of 2(3)-O-[2-(hydroxyamino)-2-oxoethyl]- and 2(3)-O-[3-(hydroxyamino)-3-oxopropyl]dextran

Hydroxame derivatives of carboxymethyl- and carboxyethyldextrans have been prepared and characterized by elemental analysis as well as by IR and UV spectroscopy. The effect of reaction conditions on the products yield has been studied.     

Bromination of 4-(2-thienyl)thiazoles and 2-(2-thienyl)quinoline

Depending on the substituent, the bromination of 4-(2-thienyl)thiazoles and 2-(2-thienyl)quinoline takes place in the 5 position of the thiophene or thiazole ring. When an amino group is present in the 2 position of the thiazole ring, bromination takes place in the 5 position of the thiazole ring. When excess brominating agent is present, a second bromine atom enters the 5 position of the free ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 35–38, January, 1982.     

Raman spectroscopic and structural studies of indigo and its four 6,6'-dihalogeno analogues

The Raman and electron impact mass spectra of synthetic indigo and its four 6,6'-dihalogeno analogues are reported and discussed. The influence of varying the halogen on these Raman spectra is considered. Particular emphasis is laid on distinguishing indigo from 6,6'-dibromoindigo and differentiating between the dihalogenocompounds, so as to develop protocols for determining whether artefacts are coloured with dyes of marine or terrestrial origin and whether such artefacts are dyed with genuine "Tyrian Purple" or with dihalogenoindigo substitutes that do not contain bromine. The value of even low resolution electron impact mass spectrometry in a forensic context as a means of identifying authentic 6,6'-dibromoindigo and distinguishing it from its dihalogenoanalogues is emphasised     

Voltammetric and spectroscopic studies of water/formamide ratios in the production of the cerium (III) hexacyanoferrate (II) nanoparticles

The present study describes the simple and fast preparation of Cerium (III) hexacyanoferrate (II) (CeHCF) solid nanoparticles at three different water/formamide (%) ratios used as solvent (v/v) (100:0, 80:20, 0:100). CeHCF nanoparticles (Nps) were characterized by fourier transform infrared pectroscopy (FTIR), x-ray diffraction (XRD), scanning electron microscopy (SEM), zeta potential and cyclic voltammetry (CV). Electrodes modified with CeHCF presented a well-defined redox pair with formal potential (E^o′) of approximately 0.29 V (vs. Ag/AgCl(sat) attributed to the Fe^{2 +}/Fe³⁺ redox pair in the presence of cerium (III)). The Nps in the three systems investigates, presents a random size distribution to different surface, where most were distributed between 20 and 160 nm. Considering the three investigated systems, only CeHCF-1 (100:0) was sensitive to L-dopamine, presenting a linear signal region as a function of L-dopamine concentrations, with a limit of detection (LD) of 0.125 mmol L⁻¹, limit of quantification (LQ) of 0.419 mmol L⁻¹ and amperometric sensitivity (S) of 148.16 μA mmol L⁻¹.     

Thermochemical study of the trans- and cis-isomeric forms of 4-(4-methoxystyryl)pyridine N-oxide

The trans and cis form of 4-(4-methoxystyryl)pyridine N-oxide were studied. The spectral characteristics of cis-4-(4-methoxystyryl)pyridine N-oxide were determined in acetonitrile. The melting and thermal decomposition processes of the trans and cisforms of 4-(4-methoxystyryl)pyridine N-oxide were studied by thermochemical methods. It was establish that the thermal decomposition of 4-(4-methoxystyryl)pyridine N-oxide begins with the cleavage of the bond between the pyridine and benzene rings.

     

新试剂5-(4-氯苯基偶氮)-8-苯磺酰氨基喹啉光度法测定微量铜

在 p H 8.5的 Na2 B4 O7- HCl介质及有氯化十六烷基吡啶 ( CPC)存在时 ,室温下铜 ( )与 5 - ( 4 -氯苯基偶氮 ) - 8-苯基磺酰氨基喹啉 ( CPBSQ)迅速反应 ,生成络合比为 1∶ 3的有色络合物。研究了反应的最佳条件 ,建立了一个测定 Cu( )的光度分析新方法。Cu( )的浓度在 0～ 1 4.0 μg/2 5 m L 范围内符合比耳定律 ,其摩尔吸光系数为 8.1 2× 1 0 4 L· mol- 1· cm- 1。方法用于面粉、茶叶及奶粉中铜的测定 ,其相对标准偏差为 0 .5 8%～ 1 .2 % ,标准加入回收率为 95 .5 %～ 1 0 4 .5 %。     

5-(4-硝基苯偶氮)-8-(4-甲苯磺酰氨基)-喹啉的合成及在钴的测定中的应用研究

首次合成了5-(4-硝基苯偶氮)-8-(4-甲苯磺酰氨基)-喹啉,测量了其酸离解常数。在非离子型表面活性剂存在下,试剂与钴(Ⅱ)在pH9.0～11.2范围内形成配合物,ε_(645)=1.01×10~5L·mol~(-1)cm~(-1),在H_2o_2作用下,于λ_((?)m)/λ_((?)x)=420nm/345nm产生强荧光,建立了一个操作简便快速、灵敏度高、选择性好的荧光分析新方法,线性范围2～32ppb,检测极限0.1ngCo(Ⅱ)/ml,用以测量了维生素B_(12)及生物样品中的痕量钴(Ⅱ)。探讨了H_2O_2对荧光增敏的机理。     

Voltammetric and spectroscopic investigations of 4-nitrophenylferrocene interacting with DNA

Cyclic voltammetry (CV) coupled with UV–vis and fluorescence spectroscopy were used to probe the interaction of potential anticancer drug, 4-nitrophenylferrocene (NFC) with DNA. The electrostatic interaction of the positively charged NFC with the anionic phosphate of DNA was evidenced by the findings like negative formal potential shift in CV, ionic strength effect, smaller bathochromic shift in UV–vis spectroscopy, incomplete quenching in the emission spectra and decrease in viscosity. The diffusion coefficients of the free and DNA bound forms of the drug were evaluated from Randles–Sevcik equation. The binding parameters like binding constant, ratio of binding constants (K_red/K_ox), binding site size and binding free energy were determined from voltammetric data. The binding constant was also determined from UV–vis and fluorescence spectroscopy with a value quite close to that obtained from CV.     

Solid-phase synthesis and spectroscopic studies of TRH analogues incorporating cis- and trans-4-hydroxy-L-proline.

An efficient solid-phase synthesis of the TRH analogue Glp-His(Nim-Trt)-Hyp-OH is described. Na-Fmoc protected amino acids and DCC/HOBt activation were employed. The bulky and mild-acid-sensitive 2-chlorotrityl resin, utilised as the solid support, completely suppressed dioxopiperazine formation. The tripeptide is a key intermediate in the synthesis of TRH analogues incorporating cis- and trans-4-hydroxy-L-proline. The tripeptide was converted, with inversion of configuration at C-4 of the Hyp residue, to Glp-His(Nim-Trt)-cHyp lactone in the presence of triphenylphosphine-diethyl azodicarboxylate (TPP-DEAD). One-pot MeOH-TPP-DEAD transesterification of the lactone, followed by Nim-detritylation, provided Glp-His-cHyp-OMe. This ester gave the corresponding amide and acid on ammonolysis and saponification, respectively. A high-field 1H NMR investigation of Glp-His-cHyp-OH and its diastereomer Glp-His-Hyp-OH, obtained by Nim-detritylation of the key tripeptide, showed that the configuration at C-4 of the prolyl residues is critical for the determination of the preferred three-dimensional structure of the molecules.     

Synthesis,spectroscopic (FT-IR and NMR), DFT and molecular docking studies of ethyl 1-(3-nitrophenyl)-5-phenyl-3-((4-(trifluoromethyl)phenyl)carbamoyl)-1H-pyrazole-4-carboxylate

Research on Chemical Intermediates - Trifluoromethyl group containing pyrazole-3-carboxamide derivative is synthesized and the structure of the molecule (E3N5PC) has been verified by using FT-IR,...     

A new approach to (S)-4-hydroxy-2-pyrrolidinone and its 3-substituted analogues

Successive treatment of a phenyl thioether derived from (S)-malic acid with n-BuLi, lithium naphthalenide (LN), and electrophiles led to 4-hydroxy-3-substituted 2-pyrrolidinones in one-pot and in high regio- and diastereoselectivity at C-3. N-Debenzylation of 1-benzyl-4-hydroxy-2-pyrrolidinone using LN afforded naturally occurring (−)-(S)-4-hydroxy-2-pyrrolidinone. (−)-(3S,4S)-4-Hydroxy-3-methyl-2-pyrrolidinone, the lactam form of the γ-amino acid residue found in marine natural products, bistramides, was prepared by the same method.