铽配合物Tb(PMIP)3(PhCA)的合成及阴离子识别研究

本文设计合成了稀土铽配合物Tb(PMW)3(PhCA)作为阴离子试剂,利用荧光光谱考察了其与F-、Cl-、Br-、I-、ClO4-、NO3-、AcO-和H2PO-4等阴离子的作用.研究结果表明:不同阴离子的加入能够调控,Tb(PMIP)3(PhCA)的发光行为,当一定量的氟离子(醋酸根离子、磷酸二氢根离子)加入到Tb(PMIP)3(PhCA)的乙腈溶液中后,荧光发射增强;过量的氟离子(醋酸根离子、磷酸二氢根离子)加入后则使其荧光淬灭.而在乙腈和水混合溶液中,Tb(PMIP)3(PhCA)则能选择性识别氟离子和磷酸二氢根离子.     

Thin-film solid-state electroluminescent devices based on tris(2,2'-bipyridine)ruthenium(II) complexes

The behavior of light-emitting electrochemical cells (LEC) based on solid films ( approximately 100 nm) of tris(2,2'-bipyridine)ruthenium(II) between an ITO anode and a Ga-In cathode was investigated. The response times were strongly influenced by the nature of the counterion: small anions (BF(4)(-) and ClO(4)(-)) led to relatively fast transients, while large anions (PF(6)(-), AsF(6)(-)) produced a slow time-response. From comparative experiments of cells prepared and tested in a glovebox to those in ambient, mobility of the anions in these films appears to be related to the presence of traces of water from atmospheric moisture. An electrochemical model is proposed to describe the behavior of these LECs. The simulation results agreed well with experimental transients of current and light emission as a function of time and show that the charge injection is asymmetric at the two electrodes. At a small bias, electrons are the major carriers, while for a larger bias the conduction becomes bipolar.     

A pyrophosphate-responsive gadolinium(III) MRI contrast agent

This study shows that the relaxivity and optical properties of functionalised lanthanide‐DTPA‐bis‐amide complexes (lanthanide=Gd³⁺ and Eu³⁺, DTPA=diethylene triamine pentaacetic acid) can be successfully modulated by addition of specific anions, without direct Ln³⁺/anion coordination. Zinc(II)‐dipicolylamine moieties, which are known to bind strongly to phosphates, were introduced in the amide “arms” of these ligands, and the interaction of the resulting Gd–Zn₂ complexes with a range of anions was screened by using indicator displacement assays (IDAs). Considerable selectivity for polyphosphorylated species (such as pyrophosphate and adenosine‐5′‐triphosphate (ATP)) over a range of other anions (including monophosphorylated anions) was apparent. In addition, we show that pyrophosphate modulates the relaxivity of the gadolinium(III) complex, this modulation being sufficiently large to be observed in imaging experiments. To establish the binding mode of the pyrophosphate and gain insight into the origin of the relaxometric modulation, a series of studies including UV/Vis and emission spectroscopy, luminescence lifetime measurements in H₂O and D₂O, ¹⁷O and ³¹P NMR spectroscopy and nuclear magnetic resonance dispersion (NMRD) studies were carried out.     

A Six-Armed Phenhomazine Ligand with a Potential “Turn-Off” Copper(II) Sensing Capability through Terbium(III) Luminescence Quenching

Herein, the design, synthesis, and characterization of a phenhomazine ligand are described. The ligand has six pendant acetate arms designed for the combined coordination of copper(II) and lanthanide(III) ions, with the perspective of developing a “turn-off” copper sensor. The key step for the ligand preparation was the one-step endomethylene bridge fission of a diamino Tröger's base with a concomitant alkylation. Fluorescence and absorption spectroscopies as well as nuclear magnetic resonance (NMR) experiments were performed to analyze and understand the coordination properties of the ligand. Transition metal coordination was driven by the synergistic effect of the free nitrogen atoms of the diazocinic core and the two central acetate arms attached to those nitrogen atoms, whereas lanthanide coordination is performed by the external acetate arms, presumably forming a self-assembled 2:2 metallosupramolecular structure. The terbium complex shows the typical green emission with narrow bands and long luminescence lifetimes. The luminescence quenching produced by the presence of copper(II) ions was analyzed. This work sets, therefore, a starting point for the development of a phenhomazine-based “turn-off” copper(II) sensor.     

Smart pH sensitive luminescent hydrogel based on Eu(III) β-diketonate complex and its enhanced photostability

A luminescent hydrogel was successfully prepared by immobilizing an europium(III) tetrakis(β-diketonate) complex into a gallate-based hydrogelator. The Eu(III) emission in hydrogel media was switched reversibly “on-off” as a function of pH and the corresponding thermal and photostabilities dramatically increased compared with its solution sample.     

Allosteric manipulation of photoexcited state relaxation in (bpy)2RuII(binicotinic acid)

The emission spectrum and luminescent lifetime of (bpy)2RuII(binicotinic acid) is affected by the presence of heavy metal ions in solution. As little as 1 microM Pb2+ causes a red shift in emission, an increase in the emission quantum yield, and an increase in the room-temperature lifetime. A smaller red shift is observed in the 4,4'-dicarboxy analogue in the presence of large quantities of lead; however, the emission lifetime and intensity are diminished. An X-ray determination of the ground-state geometry shows that the bipyridine rings of the binicotinic acid are twisted along the 2,2' bond by 19.3 degrees. The interaction between lead and the binicotinic acid complex was modeled by molecular mechanics and extended Hückel calculations. The calculations show that interaction with lead flattens the bridged ring system of the binicotinic acid ligand, which affects the pi* energy levels of the ligand, the d-orbital energies of the Ru(II), and the vibrational modes available to the substituted bipyridine ligand. The inverse energy gap law behavior observed in the binicotinic acid complex is explained in terms of an allosteric interaction between lead and the binicotinic acid complex.     

Sensing Uranyl(VI) Ions by Coordination and Energy Transfer to a Luminescent Europium(III) Complex

The release of uranyl(VI) is a hazardous environmental issue, with limited ways to monitor accumulation in situ. Here, we present a method for the detection of uranyl(VI) ions through the utilization of a unique fluorescence energy transfer process to europium(III). Our system displays the first example of a “turn‐on” europium(III) emission process with a small, water‐soluble lanthanide complex triggered by uranyl(VI) ions.     

Primary amines via electrophilic amination of organometallic compounds with o-(diphenylphosphinyl)hydroxylamine

It is shown that O-(diphenylphosphinyl)hydroxylamine $\text{4a}$ transforms all kinds of “carbanions” into primary amines; best yields are received with “stabilized anions”, e.g. of the benzylic type.     

Lanthanide Compounds with SCHIFF Bases and with Copper(II) SCHIFF Base Complexes as Ligands

Lanthanide adducts with N,N′-bis(salicylidene)-1,3-propylendiamine and N,N′-bis(salicylidene)-1,3-propylendiamine-2-olo have been prepared. It is noted that the molecules, and not anions, of the SCHIFF bases are coordinated with the metal ion. Bi- and trinuclear lanthanide complexes with the “complex ligand”, N,N′-1,3-propylen-bis-(salicylideniminato)copper(II), coordinating as a bidentate ligand, have also been isolated. The compounds have been characterized by elemental analyses, molar conductance, electronic and infrared spectra. Possible structures for the complexes have been proposed.     

Synthesis, Crystal Structure and Electrochemistry of Two Complexes(YLn)3+[PW12O40]3-(L=Me2SO, Me2NCHO)

The reaction of a-H3[PWi2O40]with Y(NO3)3 in the presence of DMF or DMSO leads to two complexes complex 1 consists of discrete [YLn]3 cations and α-Keggin heteropolyanions [PW12O40]3-, whereas, in complex 2,donor-acceptor interaction results in a cation-anion-cation triplet. In addition, the electrochemical behavior of the two complexes indicates the usual successive reduction processes of the W atoms in the anions.     

Studies on Binuclear Co(II) and Cu(II) Complexes of Tridentate N-(2-Carboxyphenyl)Salicylideneimine

Homo Cu(II) and Co(II) binuclear complexes H[MLClMCl₂] formed by using the donor properties of the cis two oxygen atoms of the tridentate N-(2-carboxyphenyl)-salicylaldimine Schiff base derived from salicylaldehyde and anthranilic acid have been synthesized. It was found that the Cu(II) “complexed ligand” readily reacts with CoCl₂ to form mononuclear Co(II) and binuclear oxygen bridged Co(II) complex [Co₂-L₂](H₂O)₂. The structure of the so prepared complexes was investigated using microchemical analysis, molar conductance measurements as well as electronic and vibrational spectral studies. It was concluded that in the Cu(II) binuclear complex, the Cu(II) ion inside the “complexed ligand” has a planar structure while the other Cu(II) ion is distorted away from planarity. In the Co(II) binuclear complex, the Co atom of the “complexed ligand” is distorted from tetrahedral structure when it coordinates to the second Co atom.     

Terpy(Pt–salphen)2 Switchable Luminescent Molecular Tweezers

The design and synthesis of switchable molecular tweezers based on a luminescent terpy(Pt‐salphen)₂ ( 1 ; terpy=terpyridine) complex is reported. Upon metal coordination, the tweezers can switch from an open “W”‐shaped conformation to a closed “U”‐shaped form that is adapted for selective recognition of cations. Closing of the tweezers by metal coordination (M=Zn²⁺, Cu²⁺, Pb²⁺, Fe²⁺, Hg²⁺) was monitored by ¹H NMR and/or UV/Vis titrations. During the titration, exclusive formation of the 1:1 complex [M( 1 )] was observed, without appearance of an intermediate 1:2 complex [M( 1 )₂]. The crystallographic structure of the 1:1 complex was obtained with Pb²⁺ and showed a distorted helical structure. Selective intercalation of Hg²⁺ cations by the closed “U” form was observed. The tweezers were reopened by selective metal decoordination of the terpyridine ligand by using tris(2‐aminoethyl)amine (tren) as a competitive ligand without modification of the Pt–salphen complex. Detailed photophysical studies were performed on the open and closed tweezers. Structured emission was observed in the open form from the Pt–salphen moieties, with a high quantum yield and a long lifetime. The emission is slightly modified upon closing with 1 equivalent of Zn²⁺ or Hg²⁺, whereas a dramatic quenching was obtained upon intercalation of additional Hg²⁺.     

Fluorescent Supramolecular Organic Frameworks Constructed by Amidinium-Carboxylate Salt Bridges

We report here a set of fluorescent supramolecular organic frameworks (SOFs) that incorporate aggregation-induced emission (AIE) units within their frameworks. The fluorescent SOFs of this study were constructed by linking the tetraphenylethylene (TPE)-based tetra(amidinium) cation TPE⁴⁺ and aromatic dicarboxylate anions through amidinium-carboxylate salt bridges. The resulting self-assembled structures are characterized by fluorescence quantum yields in the range of 4.6∼14 %. This emissive behavior is ascribed to a combination of electrostatic interactions and hydrogen bonds that operate in concert to impede motions that would otherwise lead to excited state energy dissipation. Single-crystal X-ray diffraction analyses revealed that the length of the dicarboxylate anion bridges has a considerable impact on the structural features of the resulting frameworks. Nevertheless, all SOFs prepared in the context of the present study were found to display emissive features characteristic of TPE-based AIE luminogens with only a modest dependence on the structural specifics being seen. The SOFs reported here could be reversibly “broken up” and “reformed” in response to acid/base stimuli. This reversible structural behavior is consistent with their SOF nature.     

Molecular dynamics study of dicarbollide anions in nitrobenzene solution and at its aqueous interface. Synergistic effect in the Eu(III) assisted extraction

We report a molecular dynamics study of chlorinated cobalt bis(dicarbollide) anions [(B(9)C(2)H(8)Cl(3))(2)Co](-)"CCD(-)" in nitrobenzene and at the nitrobenzene-water interface, with the main aim to understand the solution state of these hydrophobic species and why they act as strong synergists in assisted liquid-liquid extraction of metallic cations. Neat nitrobenzene is found to well solubilize CCD(-), Cs(+) salts in the form of diluted pairs or oligomers, without displaying aggregation. In biphasic nitrobenzene-water systems, CCD(-) anions mainly partition to the organic phase, thus attracting Cs(+) or even more hydrophilic counterions like Eu(3+) into that phase. The remaining CCD(-) anions adsorb at the interface, but are less surface active than at the chloroform interface. Finally, we compare the interfacial behavior of the Eu(BTP)(3)(3+) complex in the absence and in the presence of CCD(-) anions and extractant molecules. It is found that in the absence of CCDs, the complex is trapped at the interface, while when the CCDs are concentrated enough, the complex is extracted to the nitrobenzene phase. These results are compared to those obtained with chloroform or octanol as organic phase and discussed in the context of synergistic effect of CCDs in liquid-liquid extraction, pointing to the importance of dual solvation properties of nitrobenzene or octanol to solubilize the CCD(-) salts as well as the extracted complex.     

Luminescence Color‐Tuning through Polymorph Doping: Preparation of a White‐Emitting Solid from a Single Gold(I)–Isocyanide Complex by Simple Precipitation

We report the luminescent color tuning of a new complex, 2‐benzothiophenyl(4‐methoxyphenyl isocyanide)gold(I) ( 1 ), by using a new “polymorph doping” approach. The slow crystallization of the complex 1 afforded three different pure polymorphic crystals with blue, green, and orange emission under UV‐light irradiation. The crystal structures of pure polymorphs of 1 were investigated in detail by means of single‐crystal X‐ray analyses. Theoretical calculations based on the single‐crystal structures provided qualitative explanation of the difference in the excited energy‐levels of the three polymorphs of 1 . In sharp contrast, the rapid precipitation of 1 , with the optimized conditions reproducibly afforded homogeneous powder materials showing solid‐state white‐emission with Commission Internationale de l’Éclairage (CIE) 1931 chromaticity coordinates of (0.33, 0.35), which is similar to pure white. New “polymorphic doping” has been revealed to be critical to this white emission through spectroscopic and X‐ray diffraction analyses. The coexistence of the multiple polymorphs of 1 within the homogeneous powder materials and the ideal mixing of multiple luminescent colors gave its white emission accompanied with energy transfer from the predominant green‐emitting polymorph to the minor orange‐emitting polymorph.     

Tuning the thermal properties of poly(ethylene)-like poly(esters) by copolymerization of ε-caprolactone with macrolactones,in the presence of a pyridylamidozinc(II) complex

Linear aliphatic poly(ester)s, as thermoplastic materials, are more and more envisaged as the potential “green” alternative to traditional plastics. Aliphatic polyesters having long methylene chain behave as “polyethylene-like” materials and can be prepared by ring-opening polymerization (ROP) of macrolactones. A pyridylamidozinc(II) complex was used for the ROP of ε-caprolactone (CL) and of two large ring size lactones, the ω-6-hexadecenlactone (6HDL) and the ω-pentadecalactone (PDL). High turnover frequencies were observed for the CL polymerization, while for the macrolactones, an entropy-driven behavior was recognized. Random copolymerizations of the PDL with 6HDL and of the macrolactones with CL were successfully achieved, and the copolymer microstructure was ascertained by NMR and MALDI analyses. The copolymer melting temperatures, measured by DSC, and the thermal degradation behavior, studied by TGA in nitrogen and air atmosphere, were dependent on the copolymer's composition. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 528–539     

Cyclic Voltammograms of Ferrocene on Multi‐Walled Carbon Nanotubes (MWCNTs)‐Modified Edge Plane Pyrolytic Graphite (EPPG) Electrode in Room Temperature Ionic Liquids (RTILs) of 1‐Ethyl‐3‐Methylimidazolium Tetrafluoroborate (EMIBF4)

In this work, the electrochemical behavior of ferrocene (Fc) was investigated by cyclic voltammetry (CV) in room temperature ionic liquids (RTILs) of 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (EMIBF₄) on glass carbon (GC), edge plane pyrolytic graphite (EPPG) and multi‐walled carbon nanotube (MWCNTs)‐modified EPPG electrodes, respectively. The results demonstrated that on GC electrode, pairs of well‐defined reversible peaks were observed, while for the electrode of EPPG, the peak potential separation (ΔE_p) is obviously larger than the theoretical value of 59 mV, hinting that the electrode of EPPG is distinguished from the commonly used electrode, consistent with the previous proposition that EPPG has many “defects”. To obtain an improved electrochemical response, multi‐walled carbon nanotubes (MWCNTs) were modified on the electrode of EPPG; the increased peak current and promoted peak potential separation not only proved the existence of “defects” in MWCNTs, but also supported that “creating active points” on an electrode is the main contribution of MWCNTs. Initiating the electrochemical research of Fc on the MWCNTs‐modified EPPG electrode in RTILs and verifying the presence of “defects” on both EPPG and MWCNTs using cyclic voltammograms (CVs) of Fc obtained in RTILs of EMIBF₄, is the main contribution of this preliminary work.     

Synthesis and evaluation of fluorimetric and colorimetric chemosensors for anions based on (oligo)thienyl-thiosemicarbazones

A family of heterocyclic thiosemicarbazone dyes (3a–d) containing thienyl groups has been synthesized, characterized, and their chromo-fluorogenic response in acetonitrile in the presence of selected anions was studied. Acetonitrile solutions of 3a–d show absorption bands in the 338–425 nm range, which are modulated by the groups attached to the thiosemicarbazone moiety. The fluoride, chloride, bromide, iodide, dihydrogen phosphate, hydrogen sulfate, nitrate, acetate, and cyanide anions were used in the recognition studies. Only sensing features were observed for fluoride, cyanide, acetate, and dihydrogen phosphate anions. Two different chromogenic responses were found, (i) a small shift of the absorption band due to coordination of the anions with the thiourea protons and (ii) the appearance of a new red-shifted band due to deprotonation of the receptor. For the latter process changes in the color solutions from pale-yellow to orange-red were observed. Fluorescence studies showed a different emission behavior according to the number of thienyl rings in the π-conjugated bridges. Stability constants for the two processes (complex formation+deprotonation) for receptors 3a–d in the presence of fluoride and acetate anions were determined from spectrophotometric titrations using the HypSpec program. The interaction of 3d with fluoride was studied through ¹H NMR titrations. Semiempirical calculations to evaluate the hydrogen-donating ability of the receptors were also performed.     

Atomistic Simulations of COSAN: Amphiphiles without a Head-and-Tail Design Display “Head and Tail” Surfactant Behavior

Cobaltabisdicarbollide (COSAN) anions have an unexpectedly rich self-assembly behavior, which can lead to vesicles and micelles without having a classical surfactant molecular architecture. This was rationalized by the introduction of new terminology and novel driving forces. A key aspect in the interpretation of COSAN behavior is the assumption that the most stable form of these ions is the transoid rotamer, which lacks a “hydrophilic head” and a “hydrophobic tail”. Using implicit solvent DFT calculations and MD simulations we show that in water, 1) the cisoid rotamer is the most stable form of COSAN and 2) this cisoid rotamer has a well-defined hydrophilic polar region (“head”) and a hydrophobic apolar region (“tail”). In addition, our simulations show that the properties of this rotamer in water (interfacial affinity, micellization) match those expected for a classical surfactant. Therefore, we conclude that the experimental results for the COSAN ions can now be understood in terms of its amphiphilic molecular architecture.     

Atomistic Simulations of COSAN: Amphiphiles without a Head‐and‐Tail Design Display “Head and Tail” Surfactant Behavior

Cobaltabisdicarbollide (COSAN) anions have an unexpectedly rich self‐assembly behavior, which can lead to vesicles and micelles without having a classical surfactant molecular architecture. This was rationalized by the introduction of new terminology and novel driving forces. A key aspect in the interpretation of COSAN behavior is the assumption that the most stable form of these ions is the transoid rotamer, which lacks a “hydrophilic head” and a “hydrophobic tail”. Using implicit solvent DFT calculations and MD simulations we show that in water, 1) the cisoid rotamer is the most stable form of COSAN and 2) this cisoid rotamer has a well‐defined hydrophilic polar region (“head”) and a hydrophobic apolar region (“tail”). In addition, our simulations show that the properties of this rotamer in water (interfacial affinity, micellization) match those expected for a classical surfactant. Therefore, we conclude that the experimental results for the COSAN ions can now be understood in terms of its amphiphilic molecular architecture.