Synthesis of novel biodegradable poly(ethylene glycol) analogue:Water-soluble aliphatic polyester with pendant oligo(ethylene glycol) chains

A novel poly(ethylene glycol)(PEG) analogue composed of aliphatic polyester backbone and pendant oligo(ethylene glycol) short chains is reported.The PEG analogue is a copolymer synthesized by ring-opening alternating copolymerization of succinic anhydride with 2-((2-(2-metho xyethoxy)ethoxy)methyl)oxirane.The structure of the copolymer was confirmed by ~1H NMR spectrum.The effects of the monomer feed ratio on the copolymerization were studied and the polymerization mechanism was given.The PEG analogue di...     

新型香豆素类荧光化合物的合成及荧光性质研究

合成了两种香豆素类荧光化合物6,8-二氯-7-羟基香豆素-3-羧酸（DClC）和6-氯-7-羟基香豆素-3-羧酸（MClC）,其中DClC未见文献报道,并通过红外光谱、核磁共振、质谱等手段对产物的结构进行了表征。同时首次研究了这两种香豆素衍生物的紫外、荧光性质,以及不同极性溶剂、pH值、表面活性剂等的影响。结果表明,pH对性质测定影响较大,当pH=10时,DClC和MClC的荧光强度明显增强。     

Quadracyclic Adenine: A Non‐Perturbing Fluorescent Adenine Analogue

Fluorescent‐base analogues (FBAs) comprise a group of increasingly important molecules for the investigation of nucleic acid structure and dynamics as well as of interactions between nucleic acids and other molecules. Here, we report on the synthesis, detailed spectroscopic characterisation and base‐pairing properties of a new environment‐sensitive fluorescent adenine analogue, quadracyclic adenine (qA). After developing an efficient route of synthesis for the phosphoramidite of qA it was incorporated into DNA in high yield by using standard solid‐phase synthesis procedures. In DNA qA serves as an adenine analogue that preserves the B‐form and, in contrast to most currently available FBAs, maintains or even increases the stability of the duplex. We demonstrate that, unlike fluorescent adenine analogues, such as the most commonly used one, 2‐aminopurine, and the recently developed triazole adenine, qA shows highly specific base‐pairing with thymine. Moreover, qA has an absorption band outside the absorption of the natural nucleobases (>300 nm) and can thus be selectively excited. Upon excitation the qA monomer displays a fluorescence quantum yield of 6.8 % with an emission maximum at 456 nm. More importantly, upon incorporation into DNA the fluorescence of qA is significantly less quenched than most FBAs. This results in quantum yields that in some sequences reach values that are up to fourfold higher than maximum values reported for 2‐aminopurine. To facilitate future utilisation of qA in biochemical and biophysical studies we investigated its fluorescence properties in greater detail and resolved its absorption band outside the DNA absorption region into distinct transition dipole moments. In conclusion, the unique combination of properties of qA make it a promising alternative to current fluorescent adenine analogues for future detailed studies of nucleic acid‐containing systems.     

Ruthenium(II)–Polyimine–Coumarin Light‐Harvesting Molecular Arrays: Design Rationale and Application for Triplet–Triplet‐Annihilation‐Based Upconversion

Ru^II–bis‐pyridine complexes typically absorb below 450 nm in the UV spectrum and their molar extinction coefficients are only moderate (ε<16 000 M ^?1 cm^?1). Thus, Ru^II–polyimine complexes that show intense visible‐light absorptions are of great interest. However, no effective light‐harvesting ruthenium(II)/organic chromophore arrays have been reported. Herein, we report the first visible‐light‐harvesting Ru^II–coumarin arrays, which absorb at 475 nm (ε up to 63 300 M ^?1 cm^?1, 4‐fold higher than typical Ru^II–polyimine complexes). The donor excited state in these arrays is efficiently converted into an acceptor excited state (i.e., efficient energy‐transfer) without losses in the phosphorescence quantum yield of the acceptor. Based on steady‐state and time‐resolved spectroscopy and DFT calculations, we proposed a general rule for the design of Ru^II–polypyridine–chromophore light‐harvesting arrays, which states that the ¹IL energy level of the ligand must be close to the respective energy level of the metal‐to‐ligand charge‐transfer (M LCT) states. Lower energy levels of ¹IL/³IL than the corresponding ¹M LCT/³M LCT states frustrate the cascade energy‐transfer process and, as a result, the harvested light energy cannot be efficiently transferred to the acceptor. We have also demonstrated that the light‐harvesting effect can be used to improve the upconversion quantum yield to 15.2 % (with 9,10‐diphenylanthracene as a triplet‐acceptor/annihilator), compared to the parent complex without the coumarin subunit, which showed an upconversion quantum yield of only 0.95 %.     

萤火虫氧化荧光素类似物电子光谱的理论研究

对萤火虫氧化荧光素(S)-2-(6-羟基-2-苯并噻唑基)-2-噻唑啉-4-酮(BTZ)中苯并噻唑环的N和S原子进行取代, 形成一系列萤火虫氧化荧光素类似物, 并采用TD B3LYP/6-31+G(d)方法, 通过计算氧化物中性态与羟基去质子化后的负一价态在气相、水溶液和模拟生物环境下的吸收与发射光谱, 讨论环内不同取代原子对光谱的影响. 结果表明, X₁位以O原子取代S原子的化合物的最大吸收值发生蓝移, 以N原子取代S原子的化合物的最大吸收值发生红移. 去质子化可增加苯环上π轨道成份, 降低能隙, 从而有利于提高电子跃迁几率, 使荧光发射波长红移; 通过取代X₁和X₂位杂原子, 可调节发射光谱红移达44 nm, 蓝移达41 nm(在模拟蛋白中). 6种化合物荧光发光范围较宽, 振子强度较大, 可以作为潜在的化学发光材料用于生物成像研究.     

Syntheses of Some 3—[1′（1′H）—Substituent—pyrazol—5′—yl] benzo [5,6] coumarins

3-[1′(1′H)-Substituent-pyrazol-5′-yl]benzo[5,6]coumarins and 3-(1′,2′-oxazol-5′-yl)benzo[5,6]coumarin were prepared via condensation of 3-(2′-formyl-1′-chlorovinyl)benzo[5,6] coumarin with hydrazine derivatives or hydroxylamine.Reaction of 3-[1′(1′H)-pyrazol-5′-yl]benzo[5,6]coumarin with alkyl halides,olefinic compunds or acid chlorides are described.     

含水溶液中香豆素类探针对碘离子的荧光增强识别

设计合成了新型含硫代半卡巴肼结构的香豆素类I-荧光分子探针CI,其结构用1H NMR,13C NMR,GC/MS和元素分析进行了表征,并考察了其光谱性能.结果表明CI在中性缓冲溶液中,在常见阴离子(F-,Cl-,Br-,I-,AcO-,HSO-4,H2PO-4)中能够专一性地识别I-.滴加I-后引起吸收光谱蓝移80 nm,荧光光谱蓝移6 nm,荧光增强5.9倍,溶液荧光由黄绿色变为亮蓝色.其它阴离子的存在并未干扰CI对I-的检测.     

Synthesis of bioactive indolocarbazoles: synthesis, nucleophilic ring-opening and chiral base desymmetrisation of a cyclic sulfate intermediate

A number of new functionalised bridged indolocarbazole systems have been prepared by ring-opening reactions of a key cyclic sulfate intermediate, prepared from the corresponding diol by the action of sulfuryl diimidazole and DBU. The same cyclic sulfate also undergoes an unprecedented asymmetric rearrangement to a chiral ketone, on treatment with a chiral lithium amide base.     

香豆素酰胺类化合物的合成及光谱特性

用(取代)香豆素-3-甲酰氯(Ⅰa～Ⅰc)和取代2-氨基苯并噻唑(Ⅱa～Ⅱd)作用合成了12种新的目标化合物(Ⅲa～Ⅲl),用HRMS、IR、1H NMR对化合物结构进行了表征,确定了化合物的结构,并对其紫外吸收光谱和荧光光谱进行了分析。研究发现:在紫外光谱中,新化合物(Ⅲa～Ⅲl)和原料化合物(Ⅰa～Ⅰc)相比,因共轭链的增长而使其最大吸收波长(λmax)红移;12种化合物表现出比原料化合物(Ⅰa～Ⅰc)较强的荧光性能。