海螺状碳酸钙的可控合成与荧光性能

采用液相沉淀法,以硝酸铋[Bi(NO_3)_3]为添加剂来调控碳酸钙晶体的形状与大小,制备了海螺状碳酸钙粒子.通过扫描电子显微镜(SEM)、X射线衍射仪(XRD)、热重分析仪(TGA)、原子荧光光谱仪(AFS)等对产物的结构和性能进行了表征.结果表明,在60℃条件下,添加20 mL浓度为2 g/L的Bi(NO_3)_3溶液可得到海螺状球霰石型碳酸钙粒子,且其荧光性明显增强.在碳酸钙的成核过程中,Bi~(3+)的加入起到了显著的调控作用.     

Synthetic approaches to parabens molecularly imprinted polymers and their applications to the solid-phase extraction of river water samples

In this paper we describe the synthesis, characterisation and use of two distinct molecularly imprinted polymers (MIPs) prepared using esters of p-hydroxybenzoic acid (parabens) as templates: one MIP was synthesised by precipitation polymerisation using a semi-covalent molecularly imprinting strategy with methyl paraben as the template/target (MIP 1); the second MIP was prepared in monolithic form through a conventional non-covalent molecular imprinting strategy, with butyl paraben as the template (MIP 2). MIP 1 recognized methyl paraben, showed cross-selectivity for other parabens analytes used in the study and higher affinity towards these compounds than did a non-imprinted control polymer. Similarly, MIP 2 demonstrated higher affinity towards paraben analytes than a non-imprinted control polymer.For the analysis of environmental water samples, a solid-phase extraction (SPE) protocol was developed using MIP 2 as sorbent, and results were compared to a SPE using a commercial sorbent (Oasis HLB). With MIP 2 as sorbent and butyl paraben as target, when percolating 500 mL of river water spiked at 1 μg L⁻¹ through the SPE cartridge, and using 1 mL of isopropanol as cleaning solvent, a higher recovery of butyl 4-hydroxybenzoate (butyl paraben) and a cleaner chromatogram where achievable when using the MIP compared to the commercial sorbent.     

Water-soluble γ-cyclodextrin polymers with high molecular weight and their complex forming properties

Polymeric cyclodextrins (CDs) derivatives combine the complex forming properties of CDs and properties of polymers such as high molecular weight and high solubility, justifying the increasing interest for its use in biomedical science. In this paper, a series of water-soluble epichlorohydrin/γ-CD polymers were synthesized and the influences of the epichlorohydrin/γ-CD ratio, NaOH concentration and reaction time were studied in order to get high molecular weight polymers. The M_w distribution and CD content of the polymers were determined by size exclusion chromatography and ¹H NMR, respectively. The complexing properties of the polymers were studied by isothermal titration calorimetry using Methyl Orange (MO) and Sodium Fusidate (Fus) as guests for the γ-cyclodextrin host. The complex formation with MO is exclusively enthalpy driven whereas the one with Fus is totally entropy driven.     

(Mesitylene)ruthenium π-complexes with benzo-15-crown-5 and dibenzo-18-crown-6

The reactions of benzo-15-crown-5 and dibenzo-18-crown-6 with 1 equiv. of [(mes)Ru(MeNO₂)₃]²⁺ (mes = 1,3,5-C₆H₃Me₃) give the mononuclear complexes [(mes)Ru(η⁶-benzo-15-crown-5)]²⁺ (1) and [(mes)Ru(η⁶-dibenzo-18-crown-6)]²⁺ (2) in 50% yield. Similar reaction with 2 equiv. of [(mes)Ru(MeNO₂)₃]²⁺ produces the dinuclear complex [(μ-η⁶:η⁶-dibenzo-18-crown-6)Ru₂(mes)₂]⁴⁺ (3) in 96% yield as a 2:3 mixture of cis- and trans-isomers. Structures of 2(OTf)₂ and trans-3(OTf)₄ were confirmed by X-ray diffraction. The NMR titration showed that mononuclear dications 1 and 2 bind Na⁺ ion less effective (K_a = 600 and 250 M^-1) than free benzo-15-crown-5 and dibenzo-18-crown-6 (K_a = 2 × 10⁵ and 5 × 10⁶ M⁻¹). The dinuclear tetracation 3 does not bind Na⁺ within measurable limits of NMR titration method. The electrochemical behaviour of complexes 1-3 was studied in propylene carbonate solution. They exhibit a partially chemically reversible Ru(II)/Ru(I) reduction, which in the case of the dinuclear complex 3 proceeds through two slightly separated steps. The redox activity of the complexes is substantially unaffected by the presence of sodium ion.     

Synthesis and Characterization of Uniform Fine Particles of Iron(III) Hydroxide/Oxide

Iron(III) hydroxide was precipitated from the homogeneous solutions, containing variuos amounts of iron(III) nitrate, potassium sulfate, and urea, by heating at 85 °C for different periods of time (5‐30 min). The precipitated solids were either in the form of gel or dispersed particles of different shapes and sizes, depending upon the composition of the reactant mixtures. The as‐prepared solids were amorphous in nature and were formulated as Fe(OH)₃.H₂O. On calcinations at 800 °C for 1 h, the latter converted into crystalline compound, composed of α‐Fe₂O₃ (hematite). The calcined particles retained the original features of their precursors to a maximum extent.     

Synthesis and Self‐Aggregation of Enantiopure and Racemic Molecular Tweezers Based on the Bicyclo[3.3.1]nonane Framework

A pair of molecular tweezers (syn‐ 4 ) that consists of quinoline and pyrazine units fused to a bicyclic framework is presented. The tweezers were synthesised both as a racemic mixture (rac‐ 4 ) and an enantiomerically pure form ((R,R,R,R)‐ 4 ) starting from either racemic or enantiomerically pure bicyclo[3.3.1]nonane‐2,6‐dione ( 3 ). Homochiral dimers were observed in the solid state for rac‐ 4 . The self‐association of both rac‐ 4 and (R,R,R,R)‐ 4 was studied in solution. A weak self‐association constant in CDCl₃ was estimated by ¹H NMR spectroscopic dilution titration experiments in both cases, following several proton resonances. For this purpose, a general normalisation model for the accurate determination of association constants from multiple datasets was developed. In contrast to the solid state, no diastereomeric discrimination was observed for rac‐ 4 in solution.     

Complexes of Click‐Derived Bistriazolylpyridines: Remarkable Electronic Influence of Remote Substituents on Thermodynamic Stability as well as Electronic and Magnetic Properties

2,6‐Bis(1,2,3‐triazol‐4‐yl)pyridine (btp) ligands with substitution patterns ranging from strongly electron‐donating to strongly electron‐accepting groups, readily prepared by means of Cu‐catalyzed 1,3‐dipolar cycloaddition (the “click” reaction), were investigated with regard to their complexation behavior, and the properties of the resulting transition‐metal compounds were compared. Metal–btp complexes of 1:1 stoichiometry, that is, [Ru(btp)Cl₂(dmso)] and [Zn(btp)Br₂], could be isolated and were crystallographically characterized: they display octahedral and trigonal‐bipyramidal coordination geometries, respectively, and exhibit high aggregation tendencies due to efficient π–π stacking leading to low solubilities. Metal–btp complexes of 1:2 stoichiometry, that is, [Fe(btp)₂]²⁺ and [Ru(btp)₂]²⁺, could also be synthesized and their metal centers show the expected octahedral coordination spheres. The iron compounds exhibit quite a complex magnetic behavior in the solid state including spin crossover near room temperature, and hysteresis and locking into high‐spin states on tempering at 400 K, depending on the substituents on the btp ligands. Cyclic voltammetry studies of [Ru(btp)₂]²⁺ reveal strong modulation of the oxidation potentials by more than 0.6 V and a clear linear correlation to the Hammett constant (σ_para) of the substituent at the pyridine core. Isothermal titration calorimetry was used to measure the thermodynamics of the Fe^II–btp complexation process and enabled accurate determination of the complexation enthalpies, which display a linear relationship with the σ_para values for the terminal phenyl substituents. Detailed NMR spectroscopic studies finally revealed that in the case of Fe^II complexation, dynamics are rapid for all investigated btp derivatives in acetonitrile, while replacing Fe^II by Ru^II or changing the solvent to dichloromethane effectively slows down ligand exchange. The results nicely demonstrate the utility of substituent parameters, originally developed for linear free‐energy relationships to explain reactivity in organic reactions, in coordination chemistry, and to illustrate the potential to custom‐design btp ligands and complexes thereof with predictable properties. The fast equilibration of the [Fe(btp)₂]²⁺ complexes together with their tunable stability and interesting magnetic properties should enable the design of dynamic metallosupramolecular materials with advantageous properties.     

滴定分析的终点误差随待测物浓度及反应平衡常数单调变化之商榷

为了获得滴定分析的终点误差随待测物浓度、反应平衡常数这两个因素变化的准确规律,推导了有别于林邦终点误差公式的终点误差计算式,根据该式可以判断每个因素对计算结果的影响,结合在配位滴定分析和酸碱滴定分析的具体应用,结果发现：这两个因素其大小的变化不会一定导致终点误差绝对值的单调变化。     

草酸铕颗粒微米层状颗粒的合成及其光学性能

在室温条件下, 以柠檬酸钠为辅助剂, 通过简单沉淀法合成了草酸铕Eu₂(C₂O₄)₃·10H₂O微米层状颗粒. 应用X射线衍射、X射线电子能谱、场发射扫描电子显微镜、光致发光光谱对Eu₂(C₂O₄)₃·10H₂O结构与性能进行了表征. 讨论了草酸铕微米层状颗粒可能的形成机理.     

Interaction of diethyl aniline methylphosphonate with DNA: Spectroscopic and isothermal titration calorimetry

In this study the diethyl aniline methylphosphonate (DAM) was synthesized, the interaction of DAM with ct-DNA has been investigated by fluorescence spectra, UV spectra, molecular modeling and isothermal titration calorimetry (ITC). The binding constant of DAM to ct-DNA calculated from both isothermal titration calorimetry and fluorescence spectra were found to be in the 10⁴ M⁻¹ range. According to the ethidium bromide displacement studies, UV spectra and isothermal titration calorimetry experimental results, it can be concluded that DAM is an intercalator that can slide into the G-C rich region of ct-DNA. Furthermore, the results obtained from molecular modeling corroborated the experimental results obtanied from spectroscopic and ITC investigations. At the same time, fluorescence spectra suggested that the mechanism of the interaction of DAM to ct-DNA was a static enhancing type. ITC data showed that ct-DNA/DAM binding is enthalpy controlled.