Synthesis, Crystal, Absorption and Fluorescence Spectroscopy of Nitro-Stilbene Derivatives with Benzophenones

In this paper, we have presented a range of new nitro-stilbene derivatives with benzophenones via ether or ester bridged bond. These nitro-stilbene derivatives with benzophenones have been conveniently obtained by condensation reaction. The linked benzophenones were efficiently introduced to nitro-stilbene dyes. The structures of these compounds have been characterized with NMR and element analysis. The single crystals of two target compounds (11 and 12) have been obtained, and their X-ray crystallographic data have been determined and discussed. Remarkably different absorption and fluorescence spectroscopy was observed for nitro-stilbene derivatives with benzophenones via different linked bonds. The results show that electron-donating or electron withdrawing bridged bonds have significant influence on the absorption and fluorescence spectroscopy, which makes it possible for the development of ideal nitro-stilbene dyes with benzophenones through chemical strategy.     

Synthesis and two-photon optical characterization of D-π-D type Schiff bases

The title compounds, several Schiff bases with D-π-D type have been successfully synthesized from reaction of 4-(N-dialkylamino) benzaldehyde and hydrazine or p-phenylenediamine in ethanol. These compounds were characterized by IR, ¹H NMR, elemental analysis and electronspray mass spectrometry. One-photon fluorescence and two-photon fluorescence properties have been investigated. The two-photon absorption (TPA) cross section (σ) of these compounds was obtained by using the open-aperture Z-scan technique. Based on theoretical calculations and factual test, the influence that a series of substituted groups and the conjugated frame imposed on TPA cross section were systematically discussed.     

Fluorescence Study of Dehydroabietic Acid-Based Bipolar Arylamine-Quinoxalines

The absorption and fluorescence spectra, lifetimes and quantum yields of a series of triarylaminequinoxaline bipolar compounds, with and without the bulky dehydroabietic acid group, have been studied in toluene solution. This bulky group is introduced to improve solubility and thermal properties of these systems. It is shown that this does not affect their spectral or photophysical behavior. The compounds show relatively strong fluorescence, with the emission maximum strongly dependent upon the substituents present. Oxidation potentials have also been determined in acetonitrile solution, and again indicate that introduction of the resin acid moiety has no effect on these properties.     

Study on crystalline properties of Er-Si-O compounds in relation to Er-related 1.54 μm photoluminescence and electrical properties

Er-Si-O crystalline compounds, which exhibit superlattice structures and sharp and strong Er-related 1.54 μm photoluminescence (PL) spectra at room temperature have been formed by self-assembling growth mechanism. Oxidation of the starting materials which have Si and Er at an atomic ratio of 2:1 are prepared and then oxidation and succeeding high-temperature annealing in Ar above 1250 °C cause a self-assembled superlattice-structured Er-Si-O crystalline compounds. The control of the ratio of Si and Er, as well as the following oxidation and annealing processes, is found to be sensitive to the crystalline properties, PL spectra and electrical properties. In this study, Er-Si-O crystalline thin films are formed on Si substrates by sol-gel and MOMBE methods, and their crystalline properties such as crystalline orientation and concentration ratio of Er, Si and O are investigated. Crystalline Er-Si-O films of high orientation are successfully grown on Si(1 0 0) and its inclined surface. The PL and excitation spectra, fluorescence decay and the electrical properties are found to be strongly related to the crystalline properties. Excess O causes a broader 1.54 μm PL spectra, slower fluorescence decay, lower carrier-mediated excitation and higher resistivity. A precise control of O is found to be necessary to grow superlattice-structured Er-Si-O compounds, which are semiconducting and are excitable via carrier-mediated excitation mechanism.     

吡唑林荧光化合物的合成与红外光谱研究

由苯并噻唑基及苯并咪唑基取代的吡唑林类化合物是一类新型荧光化合物。此类荧光化合物可用于多种领域,但一直发展较缓慢。依据Schellhammer经验中化学结构与荧光性关系,在吡唑林的1-位引入了苯并噻唑基或苯并咪唑基,3-位引入苯基衍生物,使其具有荧光性,5-位引入苯基作为助色团,可使荧光谱红移,增加荧光性。作者设计出新型荧光化合物的结构式,新合成了两种苯并咪唑及苯并噻唑吡唑林荧光化合物,用元素分析确定其结构。两种化合物具有较好的荧光性,荧光发射波长处在蓝绿光的范围内。经红外光谱分析,找出由苯并噻唑基或苯并咪唑基取代的吡唑林类化合物具有的典型特征吸收峰,可由此作为基准,推断化合物的结构。两种化合物的合成与光谱分析研究可为吡唑林类荧光化合物的研究开拓新途径。     

Structures and physical properties of R_2TX_3 compounds

Rare-earth compounds have been an attractive subject based on the unique electronic structures of the rare-earth elements. Novel ternary intermetallic compounds R2TX3 (R = rare-earth element or U, T = transition-metal element, X = Si, Ge, Ga, In) are a significant branch of this research field due to their complex and intriguing physical properties, such as magnetic order at low temperature, spin-glass behavior, Kondo effect, heavy fermion behavior, and so on. The unique physical properties of R2TX3 compounds are related to distinctive electronic structures, crystal structures, micro-interaction, and external environment. Most R2TX3 compounds crystallize in AlB2-type or derived AlB2-type structures and exhibit many similar properties. This paper gives a concise review of the structures and physical properties of these compounds. Spin glass, magnetic susceptibility, resistivity, and specific heat of R2TX3 compounds are discussed.     

A3Ln(Ⅲ)1-xTb(Ⅲ)x(A=邻氨基苯甲酸;Ln=La、Gd、Y; x=0-0.1)稀土配合物的荧光性能

采用共沉淀法合成了掺杂 L a、 Gd、 Y的 Tb-邻氨基苯甲酸配合物 ,研究其荧光性能 ,结果显示 ,掺杂L a、Gd、Y后 ,对 Tb配合物的发光有增敏作用 ,讨论了不同的掺杂离子 (L a、Gd、Y)及掺杂量对其荧光性能的影响。发现 ,当掺杂离子取代大部分 Tb3+时 ,其发光增强仍十分显著。     

4-苯乙炔-1, 8-萘酰亚胺荧光化合物的合成及电致发光性能

采用Pd(PPh₃)₂Cl₂-CuI为催化剂,Ph₃P为配体,4-溴-1,8-萘二酸酐为原料,在乙醇溶液中高收率地合成了4-苯乙炔-1,8-萘酰亚胺和4-对甲基苯乙炔-1,8-萘酰亚胺荧光新化合物。光谱研究表明,它们的最大紫外吸收波长(λ_UV,max)分别为374,380 nm,最大荧光发射波长(λ_FL,max)分别为446,462 nm,且有较高的荧光量子效率。电致发光性能测试表明,器件的最大发光亮度达到2250 cd/m²,是一类有潜在应用价值的小分子发光材料。     

Spectral and luminescent properties of triareno-substituted tetraazachlorins

Spectral and luminescent properties of recently synthesized compounds of a class of hydroporphyrazines, triarenotetraazachlorins, in polyvinylbutyral films have been studied. Fluorescence lifetimes have been measured in film and in solution. Fluorescence quantum yields have been estimated. It is found that annelation of aromatic rings to the pyrrole rings of the tetraazachlorin macrocycle enhances fluorescence. Quantum-chemical optimization of the geometrical structures of the free-base 1,2-trinaphthotetraazachlorins has been carried out using the AM1 method. The two isomers were shown to be highly non-planar. Spectral hole burning in absorption bands of both this compound and free-base 2,3-trinaphthotetraazachlorin in polyvinylbutyral films at 5 K in the wavelength region of titanium-sapphire laser radiation is possible and is ascribed to NH-photoisomerization. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 3, pp. 376–386, May–June, 2009.     

Synthesis, Structural, Thermal and Photo-Physical Properties of Triazine Based NLO Material

Three novel triazine based organic chromophores with D-π-A (Donor-π system- Acceptor) push-pull type have been synthesized from 2, 4-diamino-6-phenyl-1,3,5-triazine as a starting material. Structures of all the three compounds have been confirmed by UV-Visible absorption, FT-IR, NMR and Mass spectral techniques. Their photo physical and thermal properties have been investigated. Among the three compounds, 6-phenyl-2,4-((4-amino-1,5-dimethyl-2-phenyl pyrazol-3-ylidene)(4-nitro benzylidene))-diamino-1, 3, 5-triazine (NDP) showed positive solvatochromism compared to the other two compounds. The absorption in the UV region of these three compounds were found to be less dependent on solvent polarities, whereas the red shifted fluorescence was strongly dependent on solvent polarities. The TGA data indicates that all the three compounds are stable up to 160 °C. Measurement of non linear optical properties showed that there is an increased second harmonic generation (SHG) efficiency with respect to urea indicating the existence of high molecular nonlinearity in NDP.     

Steady-State and Time-Resolved Spectroscopic Characteristics of Mesoionic Oxazolones Solutions

Three new mesoionic oxazolo[3,2-b]pyridazin-2-one derivatives, in different solutions have been investigated by UV-Vis absorption, steady-state and time-resolved fluorescence methods. The effect of substituents on the extension of conjugation of the pi-electrons from mesoionic oxazolone has been evidenced by bathochromic shifts of the absorption and fluorescence maxima positions. The fluorescence decay data could be fitted to single-exponential or double-exponential function. The lifetime values are much higher in aprotic polar solvents and in the case of the derivatives that present an extension of the conjugation of pi-electrons. The properties of the compounds present a solvent dependence, being tested in micellar solutions as potential molecular probe "sensitive" to the environment polarity.     

Spectrophotometric Characteristics of New Pyridylindolizine Derivatives Solutions

Three new pyridylindolizine derivatives, 1, 2, 3-tricarbometoxi-7-(4-pyridyl)-pyrrolo[1, 2-a]pyridine (I), 1,2-dicarboethoxy-3-(4-bromobenzoyl)-7-(4-pyridyl)-pyrrolo[1,2-a]pyridine (II) and its isomer 1,2-dicarboethoxy-3- (4-bromobenzoyl) -5- (2-pyridyl) -pyrrolo[1, 2-a]pyridine (III) have been investigated in different solutions by UV-VIS absorption, steady-state, and time-resolved fluorescence methods. The effects of the substituent and solvent on the spectroscopic properties have been demonstrated. The fluorescence decay data could be fitted to a single-exponential function. The lifetime values are higher in protic polar than in aprotic apolar solvents for compound I. In the case of compounds II and III the fluorescence intensities and lifetimes are very low, with the exception of III in aprotic solvents. The absorption and fluorescence properties of the compounds showed a solvent dependence.     

Fluorescence Properties of Selected Benzo[c]phenanthridines

The fluorescence properties of selected benzo[c]phenanthridines (BPs) were examined. The effect of structure, pH and solvent on the fluorescence properties has been investigated. It was found out that the presence of charged iminium nitrogen significantly decreased the fluorescence of the compounds. The fluorescence (intensity as well as emission spectra shape) of the investigated compounds was significantly dependent on pH as well as used solvent. The utilization in epigenetic modification mechanisms studies as demethylase probe and as possible pH indicator was suggested.     

5-呋喃基-1-苯并噻唑基吡唑啉类荧光化合物的合成及光谱分析

吡唑啉衍生物具有高的蓝色荧光,并且具有高量子效率,很易于用作发光材料中电子传输层。依据Schellhammer经验中化学结构与荧光性关系,在吡唑啉的1-位引入了苯并噻唑基,3-位引入苯基衍生物,使其具有荧光性,5-位引入呋喃基作为助色团,可使荧光波长红移,增加荧光性。文章设计并合成了六种5-位引入呋喃基苯并噻唑吡唑啉类荧光化合物,通过红外光谱、荧光光谱、1HNMR、元素分析对合成的化合物进行了表征,表明这类化合物具有良好的荧光性,其最大发射波长在440～460 nm之间,经过分析得知其荧光强度的大小与衍生物中不同的取代基有关。     

若干多钒硼酸盐簇合物的光谱研究

合成了具有[(VO)₁₂O₆B₁₈O₄₂]簇骼的4种新颖的多钒硼酸盐簇合物：(enH₂)₆H₃[(VO)₁₂O₆B₁₈O₄₂]·13H₂O(1),[Ni(en)₂]₆H₃[(VO)₁₂O₆B₁₈O₄₂]·8H₂O(2),[Cu(en)₂]₅H₃[(VO)₁₂O₆B₁₈O₄₂][B(OH)₃]₂·16H₂O(3)和(enH₂)₄Na₄H₃[(VO)₁₂O₆B₁₈O₄₂]·8H₂O(4)。通过FTIR, UV-Vis DRS和荧光光谱等手段对其进行了研究,探讨了结构和性能的关系。其中,化合物(1)含有[(VO)₁₂O₆B₁₈O₄₂]的分立结构,环状B₁₈O₄₂通过8个B—(μ₃—O)—V键被两个V₆O₁₈簇夹在中间;而化合物(2)是在(1)的基础上,由6个[Ni(en)₂]各自通过两个Ni—(μ₃—O)—B与B₁₈O₄₂的桥氧配位形成另一类新的分立型结构;化合物(3)和(4)的[(VO)₁₂O₆B₁₈O₄₂]构筑单元间分别通过[Cu(en)₂]2+和无机Na+离子桥联形成二维层状结构。多钒硼酸盐簇合物的特征振动频率和这些化合物的结构相关;UV-Vis DRS表明,在205和260 nm附近出现金属氧簇化合物的荷移跃迁;用310 nm光激发, 在约415 nm处能引起由O_μ→Mo的荧光发射, 同时还研究了其荧光寿命。     

咖啡酸及其衍生物光谱特性研究

研究了不同pH值条件下 ,咖啡酸类化合物溶液的荧光及紫外光谱特性。实验结果表明 :咖啡酸类化合物有很宽的pH发光范围 (2～ 1 2 ) ,发光强度、光谱形状及峰位随pH值不同而异 ,且在pH =9～ 1 0时 ,咖啡酸类化合物荧光强度最强。研究还发现 :咖啡酸类化合物 4 位酚羟基的解离可导致荧光强度显著增强 ,而 3 位酚羟基的解离可能会导致荧光猝灭 ,并且在强酸和强碱介质中发射荧光均被显著猝灭 ;此外 ,在强碱性介质中紫外光谱形状有很大变化 ,表明咖啡酸类化合物在强碱性下分子结构发生了明显改变。     

Plasmon-enhanced fluorescence near metallic nanostructures: biochemical applications

Amplification of fluorescence is a nanoscale phenomenon which is particularly pronounced in close proximity to metal nanostructures. Due to its sharp distance dependence, it is ideally suited to monitor biorecognition reactions. Using this effect we have been able to demonstrate ultrasensitive bioassays. Two types of metal nanostructures have been employed, nanometric silver islands deposited over an ultrathin metal mirror and silver fractal structures. For the first type, metal mirrors (aluminum, gold, or silver protected with a thin silica layer) were coated with SIFs and an immunoassay (model assay for rabbit IgG or myoglobin immunoassay) was performed on this surface using fluorescently labeled antibodies. Our results show that SIFs alone (on a glass surface not coated with metal) enhance the immunoassay signal approximately 3 to 10-fold. Using a metal mirror instead of glass as support for SIFs leads to up to 50-fold signal enhancement. The second type of metal nanostructures, silver fractals, were produced by electrochemical reduction of silver nitrate deposited on sapphire covered with a thin conductive film of indium tin oxide. These structures were used as a substrate for a model rabbit IgG bioassay. The fluorescence resulting from the binding of antibody labeled with Rhodamine was highly nonuniform with distinctive hot spots. These highly fluorescent regions were correlated with areas of higher Ag thickness and coverage. Such high values of fluorescence amplification in both types of nanostructures have been interpreted by using time-resolved fluorescence data and by considering the radiative properties of plasmons in the environments which promote plasmon coupling. PACS 87.64.Ni; 81.07.-b; 87.14.-g     

若干具有[(PO4)2Mo5O15]簇骼的化合物的光谱研究

本文对所合成的具有 [(PO4 ) 2 Mo5O1 5]簇骼的 3种新颖的有机 磷钼酸盐簇合物(NH3CH2 CH2 NH3) 2 5[(PO4 ) (HPO4 )Mo5O1 5]·7 5H2 O (Ⅰ ) ,(H3NCH2 CH2 NH3) 3·[(PO4 ) 2 Mo5O1 5]·3H2 O (Ⅱ )和(H3NCH2 CH2 NH3) 2 ·[Cu(en) ][(PO4 ) 2 Mo5O1 5]·5H2 O (Ⅲ )用FTIR ,NIR Raman ,紫外 可见漫反射光谱 (UV VisDRS)和荧光光谱等研究手段 ,对其进行光谱研究 ,探讨其结构和性能的关系。在这些化合物中 ,化合物Ⅰ和Ⅱ具有孤立的 [(PO4 ) 2 Mo5O1 5]簇骼基元 ,而化合物Ⅲ的 [(PO4 ) 2 Mo5O1 5]簇骼基元是由 [Cuen]基团桥联成链 ;磷钼酸盐的特征振动频率和这些化合物的结构相关 ;UV VisDRS显示 ,在 2 0 0和 2 6 0nm左右有两个杂多化合物的特征吸收谱带 ;化合物的稳态荧光光谱中 ,观察到以 2 4 0nm激发 ,在大约 4 0 0nm附近出现的由金属氧簇Oμ→Mo跃迁激发所引起的较强的发射峰 ,在化合物 (Ⅲ )中 ,还观察到通过 [Cuen]的荷移跃迁的以 5 70nm激发所产生的 6 0 4nm的发射峰。     

Synthesis and Fluorescence Investigation of Differently Substituted Benzo[b][1,8]Naphthyridines: Interaction with Different Solvents and Bovine Serum Albumin (BSA)

A series of benzo[b][1, 8]naphthyridines has been synthesized by Friedl?nder condensation of 2-aminoquinoline-3-carbaldehyde 1 (o-aminoaldehyde) with active methylenes in basic medium. The fluorescence spectroscopic properties of some representative compounds has been studied in different organic solvents; moreover interaction with bovine serum albumin (BSA) in phosphate buffer was examined by UV-vis and fluorescence spectroscopy. The effect of electron donor-acceptor substituents on fluorescence properties of benzo[b][1, 8]naphthyridines 13(a-n) has been investigated along with their fluorescent quantum yields.     

Optical Properties of Micro-patterned Silver Nanoparticle Substrates

In this paper, we describe a novel technique for depositing metal nanoparticles (NPs) on a planar substrate whereby the NPs are micro-patterned on the surface by a simple stamp-printing procedure. The method exploits the attractive force between negatively charged colloidal metal NPs and positively-charged polyelectrolyte layers which have been selectively deposited on the surface. Using this technique, large uniform areas of patterned metal NPs, with different plasmonic properties, were achieved by optimisation of the stamping process. We report the observation of unusual fluorescence emission from these structures. The emission was measured using epifluorescence microscopy. Fluorescence lifetime behaviour was also measured. Furthermore, the μ-patterned NPs exhibited blinking behaviour under 469 nm excitation and the fluorescence spectrum was multi-peaked. It has been established that the fluorescence is independent of the plasmon resonance properties of the NPs. As well as optimising the novel NP μ-patterning technique, this work discusses the origin and characteristics of the anomalous fluorescence behaviour in order to characterise and minimise this unwanted background contribution in the use of metal NPs for plasmonic enhancement of fluorescence for optical biochip applications.