新型吡唑啉类荧光化合物的合成及光谱分析

吡唑啉衍生物作为荧光增白剂具有优良的性质,已被广泛应用于染料工业。根据Schellhammer化学结构与荧光性的经验,在吡唑啉环的1-位引入苯并噻唑基,3-位引入吲哚基,5-位引入苯基衍生物,设计并合成了六种新的吡唑啉衍生物,并且通过红外光谱、1H NMR谱、质谱和元素分析进行了确证。化合物的荧光性能测定结果显示此类化合物具有良好的荧光性,均可吸收353 nm左右紫外光,最大发射波长在430～443 nm之间,是一类很有发展前途的蓝紫色荧光化合物。荧光最大发射波长和荧光强度与取代基有关,在苯并噻唑上引入6-Br基团,化合物的荧光发射波长发生蓝移,且强度增大;而引入CH₃基团,化合物的荧光发射波长发生红移,且强度降低。取代基和溶剂极性对荧光量子产率的影响较小。荧光相对强度与荧光量子产率没有直接关系。     

Fluorescent Coumarin Derivatives with Viscosity Sensitive Emission - Synthesis,Photophysical Properties and Computational Studies

New derivatives of (benzo[d]azolyl)-benzo[f]chromenone were synthesized from the intermediate 3-(1,3-benzazol-2-yl)naphthalen-2-ol, obtained from 3-hydroxynaphthalene-2-carboxylic acid and 2-amino phenol in the presence of PCl₃ in chlorobenzene at 130–135 °C. The compounds were characterized by FT-IR, ¹ H NMR, mass spectroscopy and elemental analysis. The synthesized compounds are fluorescent which absorb in the range of 296 to 332 nm while emit in the range of 368 to 404 nm. The experimental absorption and emission wavelengths for the compounds 5 and 6 are in good agreement with those predicted using the Time-Dependent Density Functional Theory (TD-DFT) [B3LYP/6-31G(d)]. The largest wavelength difference between the experimental and computed absorption maxima was 29 nm (tetrahedrofuran) for compound 5 while for emission it was 61 nm (dichloromethane) for compound 7. The emission intensities of all the compounds decrease continuously as the viscosity of the microenvironment increases. The compounds are thermally stable up to a temperature range of 300 to 350 °C.     

Comparative Studies of Diphenyl-Diketo-Pyrrolopyrrole Derivatives for Electroluminescence Applications

Four different derivatives of diphenyl-diketo-pyrrolopyrrole (DPP) with alkyl side groups were synthesized to increase their solubility. Quantum chemical calculations revealed that the substitution influenced molecular geometry and subsequently modified absorption and photoluminescence spectra. The theoretical results were confirmed by experimental characterization. With increasing phenyl torsion the vibrational structure was less pronounced and larger Stokes shift was observed. Simultaneously, the molar absorption coefficient decreased as the deformation increased. On the other hand, the measured fluorescence quantum yields were modified only slightly. This indicates the possibility to prepare soluble derivatives without loss of quantum yields and to use these materials for construction of efficient and stable electroluminescent devices. Furthermore, the electroluminescence of the thin layer devices based on the soluble low molecular DPPs were characterized and discussed.     

Study on Photophysical Properties of Novel Fluorescent Phenanthroimidazole-Thiadiazole Hybrid Derivatives

Journal of Fluorescence - Phenanthroimidazole-thiadiazole hybrid derivatives, which are new heterocyclic compounds with fluorescence properties, were synthesized by designing a two-step reaction...     

Synthesis,Spectroscopy and Photochemistry of Novel Branched Fluorescent Nitro-Stilbene Derivatives with Benzopheonone Groups

In this article, we presented novel nitro-stilbene derivatives with one or two benzophenone groups as photoinitiators via multi-steps synthesis. The ultraviolet/visible spectroscopy and the emission spectroscopy of the compounds were determined in various solvents. The results showed that the ultraviolet/visible absorption spectroscopy of the derivatives with benzophenone moiety displayed overlap effects of nitro-stilbene and benzophenone parts. In non-polar solvents, the derivatives exhibited strong emission, while they displayed weak emission in modest and strong polar solvents. Dyes-linked benzopheonone groups displayed stronger fluorescence emission than simple chromophore parent molecules. Visible-light photoinitiating effects of the derivatives were investigated extensively. Methyl methacrylate could be photoinitiated efficiently by the derivatives with benzophenone moieties at very low concentration, even at 1 × 10⁻⁵ mol/L. While the photopolymerization efficiency of styrene initiated by the derivatives was lower than that of methyl methacrylate. Our results showed that the dye-linked photoinitators had more efficient photoinitiating than the simple mixture of dye and photoinitator. Furthermore, the derivative with two benzophenone groups displayed more excellent phototiniatiating effects than the derivative with one benzophenone group. Thermodynamics driving for the occurrence of visible-light photoinduced intramolecular electron transfer from chromophore part to benzophenone part was evaluated. Benzopinacol moiety produced in photoreaction was confirmed by nuclear magnetic resonant spectroscopy. Thermal stability of the derivatives was analyzed.     

A Highly Fluorescent Pyrene-Based Sensor for Selective Detection Of Fe3+ Ion in Aqueous Medium: Computational Investigations

In this work, we introduce a highly selective and sensitive fluorescent sensor based on pyrene derivative for Fe(III) ion sensing in DMSO/water media. 2-(pyrene-2-yl)-1-(pyrene-2-ylmethyl)-1H-benzo[d]imidazole (PEBD) receptor was synthesized via simple condensation reaction and confirmed by spectroscopic techniques. The receptor exhibits fluorescence quenching in the presence of Fe(III) ions at 440 nm. ESI–MS and Job’s method were used to confirm the 1:1 molar binding ratio of the receptor PEBD to Fe(III) ions. Using the Benesi-Hildebrand equation the binding constant value was determined as 8.485?×?10³ M^?1. Furthermore, the limit of detection (LOD, 3σ/K) value was found to be 1.81 µM in DMSO/water (95/5, v/v) media. According to the Environmental Protection Agency (EPA) of the United States, it is lower than the acceptable value of Fe³⁺ in drinking water (0.3 mg/L). The presence of 14 other metal ions such Co²⁺, Cr³⁺, Cu²⁺, Fe²⁺, Hg²⁺, Pb²⁺, K⁺, Ni²⁺, Mg²⁺, Cd²⁺, Ca²⁺, Mn²⁺, Al³⁺, and Zn²⁺ did not interfere with the detection of Fe(III) ions. The fluorescence life-time of the receptor PEBD with and without Fe³⁺ ion was found to be 1.097?×?10^?9 s and 0.9202?×?10^?9 s respectively. Similarly, the quantum yield of the receptor PEBD with Fe³⁺ and without Fe³⁺ ion was calculated, and found as 0.05 and 0.25 respectively. Computational studies of the receptor PEBD were carried out with density functional theory (DFT) using B3LYP/ 6-311G (d, p), LANL2DZ level of theory.

Graphical Abstract

     

Synthesis and Photophysics of Some Novel Imidazole Derivatives Used as Sensitive Fluorescent Chemisensors

Some novel imidazole derivatives were developed for highly sensitive chemisensors for transition metal ions. Since these compounds are sensitive to different external stimulations such as UV irradiation, heat, increasing pressure and changing the environmental pH causing colour change and so they can be used as a ??multi-way?? optically switchable material. A prominent fluorescence enhancement was found in the presence of transition metal ions such as Hg²⁺, Pb²⁺ and Cu²⁺ and this was suggested to result from the suppression of radiationless transitions from the n-??* state in the chemisensors. The existence of C-H??.O intramolecular hydrogen bonding in dmphnpi is confirmed by the Natural Bond Orbital analysis (NBO). The Mulliken, NBO charge analysis and the HOMO-LUMO energies were also calculated. The electric dipole moment (??) and the first-hyperpolarisability (??) value of the investigated molecules have been studied both experimentally and theoretically which reveal that the synthesized molecules have microscopic non-linear optical (NLO) behaviour with non-zero values. Ground and excited state DFT calculation were carried out in order to find out dipole moment and energy.     

几种咪唑-二氧杂环的含能取代衍生物的理论研究

使用DFT的B3LYP方法对几种咪唑二氧杂环化合物的分子结构、红外光谱、生成焓、爆轰性能和化学/热稳定性进行了研究.四种不同含能基团-NO₂,-NH₂,-N₃和-ONO₂对该化合物各项性能的影响进行了比较.结果表明-NO₂和-ONO₂基团有效地增加了化合物的密度,而-N³基团极大地增加了化合物的生成焓.其中-NO₂取代物爆轰性能接近1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane,-ONO₂取代物的爆轰性能低于hexahydro-1,3,5-trinitro-1,3,5-triazine.自然键轨道分析表明,这些化合物中相对较弱的键为取代基和咪唑环之间的键,以及二氧杂环中的C-O键.吸电子基团(-NO₂, -N³和-ONO₂)在分子中产生了明显的诱导效应,减弱了基团与咪唑环之间的链接,降低了对应键的键裂解能.研究表明基团的电负性与化合物的稳定性有关.考虑到化合物的爆轰性能和热稳定性,DNTNDI化合物满足高能量密度材料的要求.     

Synthesis of Novel Fluorescent Cyclohexenone Derivatives and their Partitioning Study in Ionic Micellar Media

An approach is demonstrated toward the synthesis of four novel cyclohexenone derivatives (CDs) via a convenient route of Michael addition of ethyl acetoacetate. The molecular structures of CDs were confirmed by means of FT-IR, ¹H NMR, EIMS, UV and also by X-ray single crystal structure analysis. CDs are strongly fluorescent compounds and their fluorescent spectra exhibits intense violet fluorescence. To model the binding to biological membranes the behavior of CDs in micellar solutions of a cationic surfactant, cetyltrimethylammonium bromide (CTAB) and an anionic surfactant, sodium dodecylsulfate (SDS) has also been examined. The characteristics of partition and binding interactions of CDs with CTAB and SDS were investigated by UV-Visible and fluorescence spectroscopic techniques. Higher values of all mentioned interactions in case of CTAB, compared to SDS, indicate that there are greater interactions between the CDs and CTAB than with SDS.     

平面型卟啉类衍生物吸收光谱的密度泛函计算

用于光动力疗法（PDT）中的光敏剂是一类吸收一定波长的光后达到激发三重态,然后将三重态能量转移给生物体内的氧分子使得基态氧激发为单线态氧的一类物质。目前,临床应用的光敏剂大部分是以卟啉为主的平面型分子。平面分子一般具有较大的共轭键,被光激发后系间窜跃小,三重态寿命较长,因此可以获得高产率的单线态氧。然而临床使用的这类光敏剂吸收波长位于紫外区域,照射光会对人体组织造成光损伤,因此改善临床光敏剂光毒性特征,合成具有可见光区域吸收波段的光敏剂是光动力疗法研究的重要内容之一。该研究依据密度泛函(DFT)及其含时理论(TD-DFT),对三类平面型卟啉衍生物[耳坠型卟啉(a), 三磺酸基酞菁(b), 三磺酸基酞菁合Ni(Ⅱ)(c)]的基态和激发态性质进行了严格的密度泛函计算。几何优化计算显示：分子(a)的最稳定构型中,所有原子都处于一个平面,分子直径大约是7 Å, 分子空穴达到5 Å。分子(b)所有的原子也处于同一平面,分子直径达到8 Å,但是分子空穴只有4 Å。分子(c)的最稳定构型与平面结构发生了偏离,这是由于金属Ni的四配位倾向形成变形四面体,分子的空穴变得更小。几何优化结果说明耳坠型卟啉分子大的空穴有助于其捕获更多的基态氧并进行能量传递。前线轨道能量和轨道布局计算显示：耳坠型分子(a)最高占据能量是最高的,即电子更易被激发。三类分子的最高占据轨道与最低空轨道的能级间隔分别为0.072, 0.076和0.075 a.u.,可以看出耳坠型分子(a)有最低的能级间隙。从轨道布局来看,三类分子中所有原子的p轨道参与了共轭大π键的形成,其中分子(c)中金属d轨道也参与了大π键的形成。对三类分子的吸收光谱进行了模拟,三类分子都具有卟啉特有的Soret带和Q带。(a)分子Q带位于450～900 nm,(b)分子和(c)分子的Q带位于400～800 nm, 其中(a)分子的最大吸收波段是939 nm。该研究从分子结构,轨道能量以及吸收光谱对三类卟啉类光敏剂的微观特性进行了理论计算和讨论,研究结果将为发现和开发近红外吸收的卟啉类高效光敏剂提供理论依据。     

Kamlet-Taft and Catalan Studies of Some Novel Y-Shaped Imidazole Derivatives

Some novel Y-shaped imidazole derivatives were developed and characterized by NMR and mass spectral techniques. The photophysical properties of these imidazole derivatives were studied in several solvents. The Kamlet-Taft and Catalan’s solvent scales were found to be the most suitable for describing the solvatochromic shifts of the absorption and fluorescence emission. The adjusted coefficient representing the electron releasing ability or basicity of the solvent, C _β or C _SB has a negative value, suggesting that the absorption and fluorescence bands shift to lower energies with the increasing electron-donating ability of the solvent. This effect can be interpreted in terms of the stabilization of the resonance structures of the chromophore. The observed lower fluorescence quantum yield may be due to an increase in the non-radiative deactivation rate constant. This is attributed to the loss of planarity in the excited state provided by the non co-planarity of the cinnamaldehyde ring attached to C(2) atom of the imidazole ring. Such a geometrical change in the excited state leads to an important Stokes shift, reducing the reabsorption and reemission effects in the detected emission in highly concentrated solutions.     

Synthesis of Novel Carbazole Fused Coumarin Derivatives and DFT Approach to Study Their Photophysical Properties

Novel coumarin derivatives have been synthesized by the classical Knoevenagel condensation of 4-hydroxy-9-methyl-9H-carbazole-3-carbaldehyde with active methylene compounds and characterized. Effect of solvent polarity on the photophysical properties, absorption and emission has been studied. The photophysical properties of the synthesized coumarins have been compared with some of the established analogous coumarin derivatives. Investigation of the structural parameters and understanding photophysical properties of the synthesized coumarin derivatives were carried out using Density Functional Theory (DFT) and Time Dependant Density Functional Theory (TDDFT) computations. The experimental values were correlated with the theoretical derived results. The ratio of the excited state and the ground state dipole moments was calculated by using solvatochromic and solvatofluoric data and compared with the values obtained from DFT and TDDFT computations.     

Temporal and Spatio-Temporal Dynamic Instabilities: Novel Computational and Experimental approaches

This special issue contains a concise account of significant research results presented at the international workshop on Advanced Computational and Experimental Techniques in Nonlinear Dynamics, which was held in Cusco, Peru in August 2015. The meeting gathered leading experts, as well as new researchers, who have contributed to different aspects of Nonlinear Dynamics. Particularly significant was the presence of many active scientists from Latin America. The topics covered in this special issue range from advanced numerical techniques to novel physical experiments, and reflect the present state of the art in several areas of Nonlinear Dynamics. It contains seven review articles, followed by twenty-one regular papers that are organized in five categories, namely (1) Nonlinear Evolution Equations and Applications, (2) Numerical Continuation in Self-sustained Oscillators, (3) Synchronization, Control and Data Analysis, (4) Hamiltonian Systems, and (5) Scaling Properties in Maps.     

A New Thiophenyl Pyrazoline Fluorescent Probe for Cu2+ in Aqueous Solution and Imaging in Live Cell

A new thiophenyl pyrazoline probe for Cu²⁺ in aqueous solution was synthesized and characterized by IR, NMR, HRMS and X-ray analysis. The probe displays remarkably high selectivity and sensitivity for Cu²⁺ with a detection limit of 1.919?×?10^?7 M in aqueous solution (EtOH:HEPES = 1:1, v/v, 0.02 M, pH?=?7.2). In addition, the probe is further successfully used to image Cu²⁺ in living cells and the probe possesses good reversibility.

New Cross-Linking Quinoline and Quinolone Derivatives for Sensitive Fluorescent Labeling

A variety of contemporary analytical platforms, utilized in technical and biological applications, take advantage of labeling the objects of interest with fluorescent tracers-compounds that can be easily and sensitively detected. Here we describe the synthesis of new fluorescent quinoline and quinolone compounds, whose light emission can be conveniently tuned by simple structural modifications. Some of these compounds can be used as sensitizers for lanthanide emission in design of highly sensitive luminescent probes. In addition, we also describe simple efficient derivatization reactions that allow introduction of amine- or click-reactive cross-linking groups into the fluorophores. The reactivity of synthesized compounds was confirmed in reactions with low molecular weight nucleophiles, or alkynes, as well as with click-reactive DNA-oligonucleotide containing synthetically introduced alkyne groups. These reactive derivatives can be used for covalent attachment of the fluorophores to various biomolecules of interest including nucleic acids, proteins, living cells and small cellular metabolites. Obtained compounds are characterized using NMR, steady-state fluorescence spectroscopy as well as UV absorption spectroscopy.     

Experimental and Theoretical Studies of the Spectroscopic Properties of Chalcone Derivatives

Newly synthesized, differently substituted chalcones (1,3-diaryl-2-propen-1-ones) have been studied using steady-state and time-resolved techniques combined with quantum-chemical modelling. To explore spectroscopic structure - property relationships the substituent (acceptor moiety) was chosen according to systematic variation in the Hammett parameter. It was shown that photophysical properties of the studied donor-acceptor (D-A) molecules can be predicted in terms of a simple model from the properties of individual chromophores (composite-model of decoupled moieties: donor (D) and acceptor (A)). The results of spectroscopic measurements also indicate that for investigated D-A fluorophores in medium-polar solvent, the initially populated, locally excited (LE) state (where the fundamental role plays donor moiety (D*-A)) reacts further to produce intramolecular charge transfer (ICT) state. Additionally, the experimental absorption (M _ge ) and fluorescence (M _eg ) transition dipole moments were calculated on the basis of spectroscopic data and compared with results of our quantum-chemical calculations. The absorption transition dipole moment was found to vary linearly with the Hammett substituent coefficient (σ).