水溶性磷酸盐柱[5]芳烃与吖啶橙的络合行为

本文首先构建了水溶性磷酸盐柱[5]芳烃（PP5A）与阳离子荧光染料吖啶橙（AO）主-客体络合物.然后通过紫外光谱（UV）、红外吸收光谱（IR）、分子荧光光谱（MFS）、一维和二维核磁共振（NMR）波谱技术（包括¹H NMR和NOESY）研究了PP5A与AO的络合行为.此外,还研究了pH及两种表面活性剂——十二烷基硫酸钠（SDS）和十六烷基三甲基溴化铵（CTAB）对AO/PP5A络合体系的荧光强度的影响.最后,采用分子对接计算了PP5A与AO和CTAB的络合模式及络合能.研究表明,AO与PP5A形成1：1的主-客体络合物;在pH=3~11范围内,PP5A均能使AO的荧光强度发生减弱或淬灭;SDS和CTAB的加入并不会对AO/PP5A络合体系的荧光强度产生显著影响.AO与PP5A络合时产生的荧光强度变化可为荧光传感器的设计提供理论基础.     

杯[4]芳烃纳米粒子的制备及其光谱性质研究

用再沉淀法制备了一种新型的有机纳米微粒子—杯[4]芳烃纳米粒子(CN),通过透射电镜观察其平均尺寸约为40 nm, 与杯[4]芳烃分子相比具有较好的荧光性能。在弱酸性条件下,适量的Fe3+能使其荧光发生明显猝灭,荧光猝灭值与Fe3+的浓度在一定范围内呈良好线性关系,据此建立了一种测定Fe3+的荧光新方法。在最优化条件下,测得Fe3+的线性范围和检出限分别为1.0×10-6～2.4×10-5 mol·L-1和3.1×10-7 mol·L-1。将其应用于水样中三价铁离子的定量分析,回收率和相对标准偏差都令人满意。     

Cation-mediated sandwich formation between benzene and pillar[5]arene: a DFT study

Cation–π interactions in alkali metal ion (Li⁺, Na⁺ and K⁺)–pillar[5]arene complexes and sandwiches of pillar[5]arene and benzene formed via alkali metal ions are studied in the light of density functional theory. Several possible modes of interaction between metal ions and pillar[5]arene have been studied. Results suggest that interaction is stronger in the complexes with the metal ion present inside the cavity of the pillar[5]arene as compared to that where the metal ion is outside the cavity. The calculated interaction energy further reveals that though cation–π complexes with larger number of alkali metal ions are unstable, however, corresponding sandwiches are stable, which further support the fact that pillar[5]arene–metal ion complexes can interact with other π–electron-rich species. Absorption spectra of the complexes formed undergo both blue and red shifts as compared to the pillar[5]arene.     

Mass Spectral Fragmentation Patterns of Some Substituted 10,Ll-Dihydro-5H-Dibenzo[A,D] Cycloheptene-5-One and 9,10-Dihydro-4H-Benzo [4,5]Cyclohepta[1,2-B]Thiophene-4-One

Electron impact mass spectra of some substituted 10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-one and 9,10-dihydro-4H-benzo[4,5] cyclohepta[1,2-b] thiophene-4-one have been recorded and the identity of various ions in the mass spectra established. Substituted dibenzosuberones (2-6) exhibit one main fragmentation route, which include the elimination of the tropolone molecule from the dibenzosuberone fragment cation. Their monothiophene analogues(7-11) exhibit characteristic CO elimination from the molecular ion and formation of corresponding naphtho[1,2-b]thiophene radical cation which after elimination of CS or HCS from the thiophene nuclei give rise to the benzotrophyne radical cation.     

Magnetic Field-Effect on Photoluminescence of Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) Nanoparticles in a Poly[vinyl butyral] Matrix

Abstract

In this work the magnetic field effects (MFE) on the photoluminescence of MEH-PPV film and nanoparticles were obtained using the MFE technique with continuous-wave photoexcitation. The analysis of the MFE dependence for the MEH-PPV film gave a HWHM (half-width at half maximum) ～ 65?mT and a total MFE value about 102.8% at 200?mT whereas the MFE dependence of the MEH-PPV nanoparticles showed significant broadening, with their HWHM ～ 280?mT and a total MFE value of 99% at 550?mT. By a simple theoretical model based on rate equations, the mechanism of the negative magnetic field effect was explained. The observed negative effect was the result of the dominant singlet exciton formation rate in the MEH-PPV nanoparticles. For explaining this negative effect the enhanced triplet-triplet annihilation due to confinement of triplet excitons in the nanoparticles and singlet molecular oxygen-triplet exciton annihilation were proposed.     

Electrochemical synthesis of Ag nanoparticles supported on glassy carbon electrode by means of p-isopropyl calix[6]arene matrix and its application for electrocatalytic reduction of H2O2

The silver nanoparticles were prepared on the glassy carbon (GC) electrode, modified with p-iso propyl calix[6]arene, by preconcentration of silver ions in open circuit potential and followed by electrochemical reduction of silver ions. The stepwise fabrication process of Ag nanoparticles was characterized by scanning electron microscopy and electrochemical impedance spectroscopy. The prepared Ag nanoparticles were deposited with an average size of 70 nm and a homogeneous distribution on the surface of electrode. The observed results indicated that the presence of calixarene layer on the electrode surface can control the particle size and prevent the agglomeratione and electrochemical deposition is a promising technique for preparation of nanoparticles due to its easy-to-use procedure and low cost of implementation. Cyclic voltammetry experiments showed that Ag nanoparticles had a good catalytic ability for the reduction of hydrogen peroxide (H₂O₂). The effects of p-isopropyl calix[6]arene concentration, applied potential for reduction of Ag⁺, number of calixarene layers and pH value on the electrocatalytic ability of Ag nanoparticles were investigated. The present modified electrode exhibited a linear range from 5.0 × 10⁻⁵ to 6.5 × 10⁻³ M and a detection limit 2.7 × 10⁻⁵ M of H₂O₂ (S/N = 3) using amperometric method.     

Analysis of 1H and 13C{1H} NMR Spectral Parameters and Geometries of Three Isomeric Diphenylbicyclo[2.2.1]Hept-5-Ene-2,3-Dicarboxylic Anhydrides

Diels-Alder adducts of 1,4-diphenyl-1,3-cyclopentadiene and maleic anhydride were investigated by recording the ¹H and ¹³C{¹H} NMR spectra of three isomeric diphenylbicyclo[2.2.1]hept-5-ene endo and exo 2,3-dianhydrides. the spectra were recorded in CD₂Cl₂ and analysed completely. the effect of the endo and exo configuration of the anhydride ring on the chemical shifts of the bridgehead phenyl protons is discussed. the ortho protons of the exo isomers resonate at higher field than those of the endo isomer, and the resonance pattern of the aromatic protons is narrower in the exo than the endo anhydride. the aromatic regions of the spectra are compared with the same regions of the ¹H NMR spectra of the earlier investigated addition products of 1,4-di-p-tolyl-1,3-cyclopentadiene and 1-phenyl-4-p-tolyl-1,3-cyclopentadiene with maleic anhydride. Chemical shifts of the bridge protons are explained on the basis of X-ray data of the compounds and MacroModel calculations on the minimum energy conformations.