N-取代N′-苯基哌嗪类化合物与硫杂蒽酮体系光诱导电子转移引发聚合体系的研究

本工作对N-苯基-N'-乙基呱嗪作为酮/胺光引发体系中组分之一的作用机制进行了研究。发现该特殊的胺类化合物虽包括二甲基苯胺和三乙胺两个部分,但它和酮类相组合形成的光引发体系只有较低的尤引发速率。对上述现象进行了讨论,并通过加入酸类化合物使其中一个胺发生季胺盐化,用以改进光引发效率来进一步证实文中所讨论的机制。     

Bioactive Polymers. XXVI. Immobilization of Pepsin on Biozan R

Pepsin was immobilized on BIOZAN R (Hercules) with dicyclohexylcarbodiimide as activator. The reaction product obtained has a protein content of 35–110 mg/g of polymer and a proteolytic activity between 20.85–28.75 μmol tyrosine/L·min·g of polymer). The coupling reaction rate is maximum under the following conditions: pepsin/BIOZAN R ratio = 0.52 g/g, DCCI/BIOZAN R ratio = 0.2 g/g, pH = 3.4, reaction time = 4 h.     

Non-extractable photoinitiators based on thiol-functionalized benzophenones and thioxanthones

Non-extractable photoinitiators could be advantageous for use in biological, electronic, and food packaging applications. Therefore, thioxanthone and benzophenone derivatives were synthesized from 1,6-hexane dithiol and chlorinated benzophenone or thioxanthone. The efficiency of thiol-functionalized photoinitiators in combination with amine co-initiators was compared to benzophenone and isopropylthioxanthone with amine co-initiators, and the cleavage of photoinitiator 2,2-dimethoxy-1,2-diphenylethan-1-one in acrylic resins. The reaction kinetics were analyzed using photo-differential scanning calorimetry and real-time FTIR. Coating physical properties were evaluated by pendulum and pencil hardness, steel-wool scratch and mandrel bend tests. The non-extractable photoinitiators had higher absorbance than their benzophenone or isopropylthioxanthone counterparts due to the sulfide substitution on the phenyl ring, and the free thiol groups reacted with the acrylate by either an amine catalyzed Michael addition or a free-radical chain process. The combination of thiol-functionalized photoinitiators with secondary amines provides an efficient photoinitiator system that is locked into the photopolymerized network and cannot be extracted with typical solvents.     

硫杂蒽酮光敏分解重氮盐及其用作光引发体系的研究

本工作对几种新型硫杂蒽酮化合物敏化光解重氮盐问题进行了研究。工作表明:敏化反应是通过电子转移过程实现的,重氮盐所带取代基以及溶剂对重氮盐的光解有较大影响。十分有趣的是该体系对甲基丙烯酸甲酯进行光敏自由基引发聚合的速率和其光解反应速率有很大的不同,本文对此现象进行了讨论。     

新型水溶性硫杂蒽酮类光引发剂的光化学行为研究

本文用紫外吸收光谱、荧光光谱、磷光光谱、电子自旋共振光谱对九种水溶性硫杂蒽酮类光引发剂的光学行为进行了研究,计算了摩尔消光系数、荧光量子产率、磷光量子产率,同时测定了溶剂效应对紫外、荧光光谱的影响,并对引发剂结构与光学化学性能之间的关系做了一定的探讨。     

光致噻吨酮与胺类、酚类、醇类的电子转移和氢转移反应

利用激光闪光光解方法研究了一系列胺类、酚类、醇类在脱氧乙腈中猝灭噻吨酮(TX)三重态的反应,得到了相应的瞬态吸收光谱和猝灭速率常数(kq).通过对光谱演变特性的分析,推断出三重态噻吨酮与不含有活泼氢的胺发生了电子转移反应,与含有活泼氢的胺发生了电子-质子转移反应.三重态噻吨酮与酚类、醇类反应中观察到噻吨酮加氢自由基的生成,据此推断出三重态噻吨酮与酚类、醇类发生了氢转移反应.胺类的猝灭速率常数随着反应自由能变(ΔG)的增大而减小,说明电子转移影响了噻吨酮三重态的猝灭.酚类的猝灭速率常数先随ΔG增大而减小,后随酚阳离子的酸性增强逐渐增大,可能是猝灭过程中电子转移影响减弱的同时氢转移影响逐渐增强.醇类的猝灭速率常数随着醇的α-C—H键能的增大而减小,说明α-C—H键能是影响噻吨酮三重态猝灭的关键因素.比较以前研究的胺类、酚类、醇类与三重态呫吨酮(XT)、芴酮(FL)反应的结果可知,由于分子结构差异性的影响,相关的猝灭速率常数按照呫吨酮、噻吨酮、芴酮的顺序逐渐减小.     

Antibacterial and luminescent properties of new donor–acceptor ruthenium triphenylphosphine–bipyridinium complexes

The known compounds N-(2,4-dinitrophenyl)-4,4′-bipyridinium (2,4-DNPhQ⁺), N-phenyl-4,4′-bipyridinium (PhQ⁺) and N-(4-acetylphenyl)-4,4′-bipyridinium (4-AcPhQ⁺) have been used to prepare a series of ruthenium complexes of the type [RuCl(CO)(PPh₃)₂(L)] (where, L = 2,4-DNPhQ⁺ or PhQ⁺ or 4-AcPhQ⁺). The latter complexes reacted with sulphur derivative to give [RuCl(CO)(PPh₃)₂(L)(L′)] (where, L′ = thio-9-xanthone). These new ruthenium complexes display intense, visible metal-to-ligand charge-transfer (MLCT) absorptions, due to dπ(Ru) → π*(pyridinium) excitations. The MLCT energy decreases as the acceptor strength increases in the order PhQ⁺ < 4-AcPhQ⁺ < 2,4-DNPhQ⁺. The new ruthenium complexes have been characterized by using standard analytical and spectroscopic techniques. Fluorescence and antibacterial activity of the ligands and appropriate complexes has also been carried out.     

New fluoro- and chromogenic chemosensors for the dual-channel detection of Hg and F

Two novel thioxanthone-based compounds 1a and 1b which possess thiosemicarbazone as binding site were developed for the dual-channel detection of Hg²⁺ and F⁻. Upon treatment with Hg²⁺ and F⁻ separately, the probes’ fluorescence is effectively quenched, meanwhile 1a and 1b show evident naked-eye color variations after addition of F⁻: colorless to yellow. They both exhibit specific sensitivity and selectivity for Hg²⁺ or F⁻ over other examined ions in tetrahydrofuran (THF) solution.     

Thioxanthone based water-soluble photoinitiators for acrylamide photopolymerization

The two water-soluble thioxanthone-based 2-(carboxymethoxy) thioxanthone, 1A and 2-thioxanthone-thioacetic acid sodium salts, 2A were synthesized and characterized by spectroscopic methods. The quantum yield for fluorescence emission (φ_f) in water was found to be 0.50 for 1A and 0.05 for 2A. The long phosphorescence lifetime, that is 201 and 114 ms in a matrix at 77 K for 1A and 2A, respectively, indicates a π-π∗ nature of the lowest triplet state. The triplet lifetimes were determined by laser flash photolysis as 12 and 12.6 μs for 1A and 2A. Polymerization of acrylamide (AAm) was initiated by both initiators in water. Decarboxylation of initiators was achieved during 20 min of irradiation. It was found that 2A initiated polymerization of AAm in water more efficiently than 1A.