Control of Multicolor and White Emission by Adjusting the Equilibrium between Fluorophores,Lewis Acids,and Their Complexes in Polymers

Multicolor emissive materials consisting of a single luminophore, a Lewis acid, and their complex were developed. The emission colors can be tuned by changing the concentration of the solution and the ratio of mixed solvents. Various emission colors in the solid state were observed when the complexes were added to polymers in different amounts. The color change is due to equilibrium disruption between the single luminophore, the Lewis acid, and the complex thereof. White emission was observed by appropriately controlling the equilibrium by changing the amount of the complex in the polymer.     

2,3-Diarylbenzo[b]arsole: Structural Modification and Polymerization for Tuning of Photophysical Properties

2,3-Diarylbenzo[b]arsoles were synthesized from zirconacycles and diiodophenylarsine. The structural modification to the luminophore was attained through diarylacetylene precursors, Suzuki–Miyaura coupling, and oxidation of the arsenic atom. The emission properties were controlled according to these modifications. The 2,3-diarylbenzo[b]arsoles showed aggregation-induced emission enhancement; the stronger emission was observed in the solid states than in solutions. In addition, Suzuki–Miyaura polycondensation and olefin metathesis polymerization produced main- and side-chain polymers, respectively. The resultant polymers showed different emission behaviors such as aggregation caused quenching and aggregation induced emission enhancement.     

Density-Dependent Emission Colors from a Conformation-Switching Chromophore in Polyurethanes

Achieving full-color emission from a single chromophore is not only highly desirable from practical considerations, but also greatly challenging for fundamental research. Herein, we demonstrated the density-dependent emission colors from a single boron-containing chromophore, from which multi-color fluorescent polyurethanes were prepared as well. Originating from its switchable molecular conformations, the emission color of the chromophore was found to be governed by the packing density and strongly influenced by hydrogen bonding interactions. The chromophore was incorporated into polyurethanes to achieve full-color emitting materials; the emission color was only dependent on the chromophore density and could be tuned via synthetic approach by controlling the compositions. The emission colors could also be modulated by physical approaches, including by swelling/deswelling process, compression under high pressure, and even blending the fluorescent polyurethane with non-emitting ones.     

Functionalized polynorbornenes with fragments of cholic acid and luminophore complexes of iridium(III) and copper(I) in side chains. Synthesis and photophysical properties

Copolymers containing fragments of cholic acid and luminophore complexes of iridium(III) and copper(I) in the side chains have been synthesized by metathesis polymerization. Photophysical properties of the obtained compounds have been investigated. Iridium-containing copolymers demonstrate intense photoluminescence of green, bluish-green and red colors. Copper-containing copolymers generate radiation of green and yellow-green colors. The color of photoluminescence of the metal-containing polymers is determined by the nature of copper(I) and iridium(III) complexes bonded to polymer chain.     

Synthesis,characterization, and evaluation of [Ir(ppy)2(vpy)Cl] as a polymer-bound oxygen sensor

This study reports new luminescent oxygen sensors in which the luminophore is covalently bound to the polymer matrix and compares their behavior to related sensors in which the luminophore is dispersed within the matrix. The cyclometalated iridium complex [Ir(ppy)(2)(vpy)Cl], 1, has been synthesized and characterized spectroscopically (absorption and emission) and by 1-D and 2-D (1)H NMR, elemental analysis, and X-ray crystallography. Complex 1 was attached via hydrosilation to hydride-terminated poly(dimethylsiloxane) (PDMS), yielding material 2. Successful luminophore attachment was determined spectroscopically from the emission properties, and through the altered physical behavior of 2 compared to a dispersion of 1 in PDMS. Hydrosilation of 1 with dimethylphenylsilane yielded [Ir(ppy)(2)(DMPSEpy)Cl], 3, which was fully characterized and used to probe the effect of hydrosilation on the spectroscopic properties of the luminophore. Evaluation of 2 as a luminescent oxygen sensor revealed significantly improved sensitivity over dispersions of 1 in PDMS. Material 2 was also blended with polystyrene (PS) to improve the physical properties of the sensor films. The blend sensors exhibited increased sensitivity relative to films of 2 alone and maintained short response times to rapid changes in air pressure. In contrast, 1 partitioned into the PS phase when dispersed in a PDMS/PS blend, resulting in longer sensor response times.     

Take your Positions and Shine: Effects of Positioning Aggregation-Induced Emission Luminophores within Sequence-Defined Macromolecules

A luminophore with aggregation-induced emission (AIE) is employed for the conjugation onto supramolecular ligands to allow for detection of ligand binding. Supramolecular ligands are based on the combination of sequence-defined oligo(amidoamine) scaffolds and guanidiniocarbonyl-pyrrole (GCP) as binding motif. We hypothesize that AIE properties are strongly affected by positioning of the luminophore within the ligand scaffold. Therefore, we systematically investigate the effects placing the AIE luminophore at different positions within the overall construct, for example, in the main or side chain of the olig(amidoamine). Indeed, we can show that the position within the ligand structure strongly affects AIE, both for the ligand itself as well as when applying the ligand for the detection of different biological and synthetic polyanions.     

Solvatochromic response imposed by environmental changes in matrix/chromophore entities: luminescent cyclometalated platinum (II) complex in Nafion and silica materials

Luminescent cyclometalated complex [Pt(L)py]+ (1) immobilised in Nafion film exhibits a solvatochromic shift in emission maximum from 530 to 650 nm upon immersion in ethanol but no effect is detected with aprotic organic solvents, whereas the emission of the [Pt(L)]+ luminophore anchored in silica materials shows a blue shift from approximately 665 to 550 nm upon exposure to pentane vapour but no shift is observed for ethanol vapour.     

Infrared spectra of the complexes of trifluoroethene with dimethyl ether, acetone, and oxirane: a cryosolution study

Infrared spectra of solutions of trifluoroethene and dimethyl ether, acetone, or oxirane in liquid krypton and liquid argon have been studied. For each Lewis base the formation of a 1:1 complex with the Lewis acid was observed. The C-H stretching of trifluoroethene being perturbed by a strong Fermi resonance, the complexes with trifuloroethene-d were also investigated and showed that in each case the hydrogen bond between the acid and base is of the traditional, red-shifting type. The structures of the complexes were investigated using ab initio calculations. These indicate that with dimethyl ether and acetone two different isomeres can be formed, but with a single one detected in the solution in each case. The Fermi resonance in the complex with unlabeled trifluoroethene is discussed using data derived form ab initio potential and dipole hypersurface calculations. The complexation enthalpies of the complexes were obtained from temperature dependent studies of the solutions and are discussed in relation to the ab initio complexation energies and Monte Carlo free energy perturbation calculations of solvent effects.     

Push–Pull (Iso)quinoline Chromophores: Synthesis,Photophysical Properties,and Use for White-Light Emission

The photophysical properties of a series of conjugated push–pull (iso)quinolines were studied. The compounds were synthesized by well-established and straightforward methodologies. The materials exhibited not only emission solvatochromism in a variety of nonpolar solvents, but also tunable halochromism. Some of the compounds remained moderately luminescent after protonation and had a red emissive form, which was used to obtain white-light emission, both in solution and in thin films, by controlled protonation of the initially blue–green-emitting materials. This methodology has potential applications in the fabrication of white organic light-emitting diodes with two forms of a single emitter in equilibrium.     

Gas-filled radioluminescent light sources and prospects for their further development

Luminescence of various inorganic compounds of rare earth elements as radioluminophores was studied with the aim of fabricating weak permanent light sources. Under the action of UV and tritium radiation, all the luminophores tested emit light of different colors. In the tritium gas medium, six luminophores showed emission, and for three of them (Y₂O₃:Eu, Y₂O₃:Eu, Bi, Gd₂O₃:Eu) the emission brightness was acceptable for practical use. Attempt to prepare permanent light sources with new types of luminophores using a phosphoric acid solution as a binder demonstrated the need for searching for a new binder firmly fixing the luminophore on the glass surface.     

Fluorescence quenching detection of peanut agglutinin based on photoluminescent silole-core carbosilane dendrimer peripherally functionalized with lactose

A glycocluster peripherally functionalized with a lactose (Lac: Galβ1→4Glcβ1–) derivative possessing a silole moiety as a luminophore was synthesized. The photoluminescence spectrum of the glycocluster showed extremely strong emission at 474 nm and the absolute quantum yield was estimated to be 92% in distilled water. The emission intensity was decreased by increasing the amount of peanut agglutinin (PNA), a lactose-binding lectin, and plots of the relative fluorescence intensity revealed a decline of 95% in emission intensity. Fluorescence quenching of the glycocluster upon mixing with PNA could be easily observed by the naked eye under UV irradiation, whereas no distinct change in fluorescence properties of the glycocluster was observed when wheat germ agglutinin (WGA) was employed.     

Study of the surface chemistry and morphology of single walled carbon nanotube-magnetite composites

The study of the morphologies of the single walled carbon nanotube (SWCNT), magnetite nanoparticles (MNP), and the composite based on them was carried with combined X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). These techniques together with thermogravimetric analyses (TGA) and diffuse reflectance infrared transform spectroscopy (DRIFTS) confirmed the production of pure single phases, and that the composite material consisted of MNP attached to the outer surface of the SWCNT. The Mössbauer spectroscopy (MS) research showed the presence of a large quantity of Lewis acid sites in the highly dispersed magnetite particles supported on the SWCNT outer surface. The DRIFTS carbon dioxide adsorption study of the composites revealed significant adsorption of carbon dioxide, fundamentally in the Lewis acid sites. Then, the Lewis acid sites were observed to be catalytically active. Further, the electron exchange between the Lewis acid sites and the basic or amphoteric adsorbed molecules could influence the magnetic properties of the magnetite. Consequently, together with this first ever use of MS in the study of Lewis acid sites, this investigation revealed the potential of the composites for catalytic and sensors applications.     

Diferrocenophosphaborin: A Planar‐Chiral,Redox‐Active and Anion‐Responsive Ambiphilic Ligand

A new class of Janus‐like ambiphilic ligands is introduced. The rigid diferrocene backbone in heterocycles 4‐SnP and 4‐BP creates an unprecedented chiral environment as demonstrated by multinuclear NMR and single‐crystal X‐ray studies. In addition, the ligands are redox‐responsive and the Lewis acidic borane moiety in 4‐BP can be exploited to further tune the properties: a clear decrease in the CO stretching frequency of a Vaska‐type Rh^I complex 5‐BP is observed upon addition of fluoride ions. Thus, the Lewis acid and Lewis base sites influence each other and their strength can be modulated by redox chemistry and anion binding.     

Diferrocenophosphaborin: A Planar‐Chiral,Redox‐Active and Anion‐Responsive Ambiphilic Ligand

A new class of Janus‐like ambiphilic ligands is introduced. The rigid diferrocene backbone in heterocycles 4‐SnP and 4‐BP creates an unprecedented chiral environment as demonstrated by multinuclear NMR and single‐crystal X‐ray studies. In addition, the ligands are redox‐responsive and the Lewis acidic borane moiety in 4‐BP can be exploited to further tune the properties: a clear decrease in the CO stretching frequency of a Vaska‐type Rh^I complex 5‐BP is observed upon addition of fluoride ions. Thus, the Lewis acid and Lewis base sites influence each other and their strength can be modulated by redox chemistry and anion binding.     

气液色谱法测定双(1,3)-二苯基丙二酮合铜(Ⅱ)配合物和杂茂环加合反应的热力学性质

气液色谱法是研究作为Lewis酸A的过渡金属配合物与作为Lewis碱的有机化合物B相互作用的热力学参数的有效方法,但以往工作大都采用非极性的直链角鲨烷作固定液。为将此法扩展到包含苯基配体的过渡金属配合物体系,我们采用一种新的固定液——多苄基联苯,测定了双(1,3)-二苯基丙二酮合铜(Ⅱ)与呋喃、噻吩的加合反应的热力学参数。     

B(C6F5)3: A Lewis Acid that Brings the Light to the Solid State

The straightforward coordination of the Lewis acid B(C₆F₅)₃ to classical, non‐emitting aldehydes results in solid‐state photoluminescence. Variation of the electronic properties of the carbonyl moieties lead to the modulation of the solid‐state emission colors, covering the entire visible spectrum with quantum yields up to 0.64. Steady‐state spectroscopy in combination with X‐ray diffraction analysis and DFT calculations confirm that intermolecular interactions between the Lewis adducts are responsible for the observed luminescence. Alteration of the latter interactions induces, moreover, remarkable solid‐state phenomena such as piezochromism. The versatility and simplicity of our approach facilitate the future development of solid‐state emitting materials.     

Intermolecular Charge-Transfer Luminescence by Self-Assembly of Pyridinium Luminophores in Solutions

Designing a luminophore for application both in solution and in the solid state is a highly challenging task given the distinct nature of intermolecular interactions in these phases. In this context, we demonstrate that self-assembly of non-emissive charged pyridinium luminophores enables luminescence in solutions through a mechanism that is characteristic for the crystal state. Specifically, protonation of pyridine luminophore subunits in a solution promotes oligomer formation through intermolecular π⁺-π interactions, leading to an intermolecular charge-transfer type luminescence. The luminescence turn-on by protonation is utilized for a highly efficient solution-state luminescent sensing of hydrogen chloride and sulfonic acids (TfOH, TsOH and MsOH) with detection limits spanning the range from 0.06 to 0.33 ppm. The protonation followed by self-assembly results in a bathochromic shift of the emission from 420 nm to 550 nm.     

Unsymmetrical photochromic bithienylethene-bridge tetraphenylethene molecular switches: Synthesis,aggregation-induced emission and information storage

Aggregation-induced emission(AIE) active photochromic molecules have attracted growing attention for their versatile applications.Here we designed and synthesized five newly unsymmetrical photochromic diarylethene(DAE) dyads(BTE1-5) by connecting tetraphenylethene(TPE) and aromatic substituent via bithienylethene(BTE) bridge.The chemical structures of those compounds were identified by ^1H NMR,¹³C NMR and HRMS.The absorption and emission of these dyads were investigated by UV-vis and fluore scence spectroscopy,respectively.The results showed that all those compounds exhibited typically AIE or aggregation-induced emission enhancement(AIEE) characteristic.Particularly,when an aggregationcaused quenching(ACQ) fluorophore(triphenylamine) was grafted to the molecule,connecting with TPE via BTE-bridge,the ACQ phenomenon was dissipated and converted to an AIE luminophore,and those compounds exhibited photochromism upon irradiation with alternative UV and visible light.The solution or solid of those compounds showed distinctly fluorescence switching "ON" or "OFF" observation upon irradiation with alternative UV and visible light.It is interesting that BTE1 could be applied in recording and rewritable information storage,and the cyclization quantum yields could be affected by substituent significantly.     

Red,Green, and Blue Luminescence by Carbon Dots: Full‐Color Emission Tuning and Multicolor Cellular Imaging

A facile approach for preparation of photoluminescent (PL) carbon dots (CDs) is reported. The three resulting CDs emit bright and stable red, green and blue (RGB) colors of luminescence, under a single ultraviolet‐light excitation. Alterations of PL emission of these CDs are tentatively proposed to result from the difference in their particle size and nitrogen content. Interestingly, up‐conversion (UC)PL of these CDs is also observed. Moreover, flexible full‐color emissive PVA films can be achieved through mixing two or three CDs in the appropriate ratios. These CDs also show low cytotoxicity and excellent cellular imaging capability. The facile preparation and unique optical features make these CDs potentially useful in numerous applications such as light‐emitting diodes, full‐color displays, and multiplexed (UC)PL bioimaging.     

The first catalytic highly enantioselective alkylation of ketimines--a novel approach to optically active quaternary alpha-amino acids

A series of novel ketimines with intrinsic protecting group anchoring was synthesized and allowed to react with various silylketene acetals in the presence of 5-10 mol % of a chiral Zn(OTf)(2)-(R,R)-Ph-pybox-aqua complex. The corresponding optically active quaternary alpha-amino acid derivatives were obtained in high yields and with enantioselectivities ranging from 34 % up to 95 % ee. The catalyst was studied by (1)H NMR spectroscopy and X-ray crystallography, and a dynamic equilibrium of two species was identified in solution. These are a homo-chiral 1:2 metal-ligand complex and a 1:1 metal-ligand complex, of which the latter is expected to be the actual catalyst of the diastereo- and enantioselective reaction. A strong positive nonlinear effect was observed due to the formation of a catalytically inactive 1:2 metal-ligand hetero-chiral complex. On the basis of DFT calculations and the absolute stereochemistry of the products, simultaneous coordination of the imino electrophile and a single molecule of H(2)O to the chiral Lewis acid complex is proposed. Coordination of the imine-nitrogen atom in the axial position of an octahedral complex can account for the facial selectivity as well as the diastereoselectivity observed.