1,4-二(2-苯基-1,3,4-噁二唑基-5)苯及其衍生物的研究(Ⅱ)

本文讨论了18种溶剂对1,4-二(2-苯基-1,3,4-(口恶)二唑基-5)苯及2-苯基的对位有叔丁基取代的衍生物的紫外、荧光光谱以及荧光量子产率的影响。     

1,2,3,4-四(6,′7′,-二甲基苯并噁唑)环丁烷光谱特性研究

本文测定并对1,2,3,4-四(6′,7′-二甲基苯并嗯唑)环丁烷(1)及其模型化合物反-1,2-二(6′,7′-二甲基苯并(口恶)嗯唑-1′,3′-基-2′)乙烯(2),1,2-二(6′,7′-二甲基苯并(口恶)唑-1′,3′-基-2′)乙烷(3),2-甲基苯并(口恶)唑(4)的紫外吸收光谱和荧光发射光谱进行对比。研究了化合物1由于跨环共轭效应所引起的电子光谱的变化,并从溶剂效应及晶体结构进行了探讨。     

1,4-双[5′-(2′-苯基噁唑基)苯及其2′-(4″-叔丁基苯基)衍生物的电子光谱的溶剂效应

利用紫外光谱、荧光光谱研究了1,4-双[5′-(2′-苯基(口恶)唑基)]苯及其2′-(4″-叔丁基苯基)衍生物在19种溶剂中的溶剂效应。结果表明,溶剂与二者化合物基态和激发态的作用基本相同。讨论了化合物激发态的偶极矩。     

2,2'-二苯并噁唑衍生物的合成和光性能研究

合成了16种2,2-二苯并(口恶)唑衍生物,测定了化合物的熔点、红外光谱、紫外吸收光谱、荧光发射光谱以及荧光量子产率,与1,4-二(苯并(口恶)唑1′,3′-基-2′)苯和1,4-二(苯并(口恶)唑-1′,3′-基-2′)乙烯衍生物进行了比较,讨论了它们之间光谱特性的差异.     

1,4-二(2-苯基-1,3,4-噁二唑基-5)苯及其衍生物的研究(Ⅲ)——部分无机离子对PDPDP荧光强度的影响

第三主族B(Ⅲ)、Al(Ⅲ)、Ga(Ⅲ)等离子可使1,4-二(2-苯基-1,3,4一(口恶)二唑基-5)苯的荧光增强,而Fe(Ⅲ)、Co(Ⅱ)、Ni(Ⅱ)等第八族过渡金属离子则使之荧光减弱。对这些无机离子影响1,4-二(2-苯基-1,3,4-(口恶)二唑基-5)苯的荧光强度的作用机制进行了初步的探讨。     

1,4-二(苯并噁唑-1',3'-基-2')苯衍生物的合成及其物理性能研究

合成了1,4-二(苯并(口恶)唑-1′,3′-基-2′)苯衍生物13种化合物。测定了它们的熔点、红外光谱、紫外吸收光谱、荧光发射光谱、荧光量子产率、荧光寿命和激光性能。     

E,E-1,4-二[2′,2″-(苯并噁唑基乙烯基)]苯及其衍生物的合成和光性能研究

合成了E,E-1,4-二[2′,2″-(苯并(口恶)唑基乙烯基)]苯及衍生物共14种,测定了它们的熔点、红外光谱、核磁共振氢谱、紫外吸收光谱和荧光发射光谱、荧光量子产率及激光性能。     

2,6-二取代苯并二噁唑的研究(Ⅳ)——2,6-二苯乙烯基苯并二噁唑及其对位衍生物的HMO计算及光谱的取代基效应

本文用HMO方法计算处理了2,6-二苯乙烯基苯并[1,2d;4,5d＇)-二(口恶)唑和2,6-二苯乙烯基苯并[1,2d;5,4d＇]-二(口恶)唑和它们的各十种对位取代衍生物,得到它们的π电子能级与分子图,对其中一些化合物的紫外(UV)和荧光(FL)光谱的取代基效应也在HMO理论基础上进行了若干分析。     

1,2,3,4-四(6,7,-二甲基苯并 唑)环丁烷光谱特性研究

本文测定并对1,2,3,4-四(6',7'-二甲基苯并 唑)环丁烷(1)及其模型化合物反-1,2-二(6',7'-二甲基苯并 唑-1',3'-基-2')乙烯(2), 1,2-二(6',7'-二甲基苯并唑-1',3'-基-2')乙烷(3), 2-甲基苯并 唑(4)的紫外吸收光谱和荧光发射光谱进行对比。研究了化合物1由于跨环共轭效应所引起的电子光谱的变化, 并从溶剂效应及晶体结构进行了探讨。     

1,2,3,4-四(6,7,-二甲基苯并 唑)环丁烷光谱特性研究

本文测定并对1,2,3,4-四(6',7'-二甲基苯并 唑)环丁烷(1)及其模型化合物反-1,2-二(6',7'-二甲基苯并 唑-1',3'-基-2')乙烯(2), 1,2-二(6',7'-二甲基苯并唑-1',3'-基-2')乙烷(3), 2-甲基苯并 唑(4)的紫外吸收光谱和荧光发射光谱进行对比。研究了化合物1由于跨环共轭效应所引起的电子光谱的变化, 并从溶剂效应及晶体结构进行了探讨。     

两种氧氮杂环戊二烯类化合物的紫外和荧光光谱的溶剂效应

前文报道了1,4-二(5-苯基-1,3,4-嚼二唑基-2)苯(PDPDP)紫外、荧光光谱的溶剂效应.为了与PDPDP比较,又合成了1-(5-苯基-1,3,4-噁二唑基-2)-4-(5′-苯基-1′,3′-噁唑基-2′)苯(PDPOP)和1-(5-苯基-1,3,4-噁二唑基-2)-4-(2′-苯基-1′,3′噁唑基-5′)苯(PDPO′P).     

An exceptional red shift of emission maxima upon fluorine substitution

The effect of perfluorination on photophysical properties was investigated through synthesis and photophysical characterization of two isostructural donor-acceptor-donor dye molecules. The synthesis of two versatile fluorinated benzene compounds, 1,4-difluoro-2,5-diperfluorooctylbenzene (1) and 1,4-dibromo-2,5-difluoro-3,6-diperfluorooctylbenzene (2), is presented. The X-ray structure of 2 has been determined and shows that the perfluorinated octyl chains segregate from the benzene rings in the solid state, giving rise to a layered structure. The further synthesis through Suzuki coupling reactions using 4-formylbenzeneboronic acid with (2) and 1,4-dibromo-2,5-dioctylbenzene (3) gave, respectively, 1,4' '-diformyl-2',5'-difluoro-3',6'-diperfluorooctyl-p-terphenylene (4) and 1,4' '-diformyl-2',5'-dioctyl-p-terphenylene (5). The condensation of the dialdehydes 4 and 5 with 9,10-phenanthrenequinone and ammoniumbicarbonate in glacial acetic acid gave the dye molecules 1,4' '-bis(1H-phenanthro[9,10-d]imidazol-2-yl)-2',5'-difluoro-3',6'-diperfluorooctyl-p-terphenylene (6) and 1,4' '-bis(1H-phenanthro[9,10-d]imidazol-2-yl)-2',5'-dioctyl-p-terphenylene (7), respectively. The UV-vis spectra of the two molecules are nearly identical, whereas the fluorescence spectra are very different. Compound 7 shows blue fluorescence with little solvent dependence (lambda(emission) = 410 nm in THF, CH2Cl2, and hexane), whereas compound 6 shows a highly solvent-dependent emission wavelength (lambda(emission) = 583 nm in THF, lambda(emission) = 560 nm in CH2Cl2, and lambda(emission) = 450 nm in hexane). The fluorescence red shift of compound 6 in a series of solvents with different polarity is discussed using the Lippert-Mataga equation. Fluorescence lifetime and quantum yields were also determined. Ultraviolet photoelectron spectroscopy (UPS) was performed on thin films of compound 6 and 7 on a gold substrate. The observed ionization potential was 6.15 eV for 6 and 5.85 eV for 7" [correction].     

Solvatochromism of 3-[2-(4-diphenylaminophenyl)benzoxazol-5-yl]alanine methyl ester. A new fluorescence probe

The photophysical properties of 3-[2-(4-diphenylaminophenyl)benzoxazol-5-yl]alanine methyl ester (1b) and its Boc derivative (1a) were studied in a series of solvents. Its UV-Vis absorption spectra are less sensitive to the solvent polarity than the corresponding fluorescence spectra which show pronounced solvatochromic effect leading to large Stokes shifts. Using an efficient solvatochromic method, based on the molecular-microscopic empirical solvent polarity parameter E(T)(N), a large change of the dipole moment on excitation has been found. From an analysis of the solvatochromic behaviour of the UV-Vis absorption and fluorescence spectra in terms of bulk solvent polarity functions, f(epsilon(r),n) and g(n), a large excited-state dipole moment (mu(e) = 11D), almost perpendicular to the smaller ground-state dipole moment, was observed. This demonstrates the formation of an intramolecular charge-transfer excited state. Large changes of the fluorescence quantum yields as well as the fluorescence lifetimes with an increase of a solvent polarity cause that the new non-proteinogenic amino acid, 3-[2-(4-diphenylaminophenyl)benzoxazol-5-yl]-alanine methyl ester, is a new useful fluorescence probe for biophysical studies of peptides and proteins.     

几种荧光有机化合物的电荷转移光谱

具有荧光的有机化合物是一些具有多个共轭双键,分子呈平面结构,有大的电子离域体系的化合物.     

Synthesis and isomerization reaction of 2-(benzoxazol-2-yl)-1,3-tropolones

An acid-catalyzed reaction of 2-methylbenzoxazole with 3,4,5,6-tetrachloro-1,2-benzoquinone leads to 2-(benzoxazol-2-yl)-5,6,7-trichloro-1,3-tropolone and 2-(benzoxazol-2-yl)-4,5,6,7-tetrachloro-1,3-tropolone. 1,3-Tropolones upon reflux in ethyl alcohol undergo the rearrangement resulted in the seven-membered ring contraction to form ethyl 2-(benzoxazol-2-yl)-5,6-dichloro-3-hydroxybenzoate and ethyl 2-(benzoxazol-2-yl)-4,5,6-trichloro-3-hydroxybenzoate. The molecular structure of the latter was established by X-ray diffraction analysis.     

Fluorescence quenching and laser photolysis of dipyrrolylbenzenes in the presence of chloromethanes

Fluorescence quenching of 1,4-bis(1H-pyrrol-1-yl)benzene, 1-(1H-pyrrol-2-yl)-1-(1-vinyl-1H-pyrrol-1-yl)benzene, and 1,4-bis(1-vinyl-1H-pyrrol-2-yl)benzene with chloromethanes (methylene chloride, chloroform, and carbon tetrachloride) in solvents with different polarities follows electron-transfer mechanism. The occurrence of an electron-transfer step is confirmed by formation of short-lived pyrrolylbenzene radical cations. An exception is quenching of fluorescence of 1,4-bis(1-vinyl-1H-pyrrol-2-yl)benzene in n-hexane in the presence of CCl₄ and CHCl₃ and in pure CCl₄. In this case, neutral 1,4-bis(1-vinyl-1H-pyrrol-2-yl)benzene^·-Cl radical is formed via recombination of 1,4-bis(1-vinyl-1H-pyrrol-2-yl)benzene radical cation and chloride anion. A relation was found between the nature of the short-lived species detected by laser photolysis and stable product obtained by stationary photolysis.     

Spectral,luminescent, and photophysical properties of dipyrrolylbenzenes

Dipyrroles with a phenylene bridge, 1,4-bis(pyrrol-2-yl)benzene, 4-(1-vinylpyrrol-2-yl)-1-(pyrrol-2-yl)benzene, and 1,4-bis(1-vinylpyrrol-2-yl)benzene, show intense room-temperature fluorescence in solutions. Analysis of electronic absorption spectra, fluorescence spectra, and results of B3LYP, TD B3LYP, and CIS quantum chemical calculations showed that the introduction of a bulky substituent in position 1 of the pyrrole ring makes the ground-state structures of dipyrrolylbenzenes less planar. Excited-state geometries of all molecules relax to more planar conformations. An increase in the probability of nonradiative transitions has little effect on the quantum yields of fluorescence (Φ_f) of dipyrrolylbenzenes. Even for 1,4-bis(1-vinylpyrrol-2-yl)benzene, where the pyrrole rings deviate from the benzene ring plane by 44°, the fluorescence efficiency remains high enough (Φ_f = 0.7). Substitution at nitrogen atoms has little effect on positions of fluorescence band maxima. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1433–1438, July, 2008.     

Solvatochromism of 3-[2-(aryl)benzoxazol-5-yl]alanine derivatives

The photophysical properties of N-Boc-3-[2-(9-anthryl)benzoxazol-5-yl]-l-alanine methyl ester (BoxAnt) and N-Boc-3-[2-[4-(9′-(10′-butyl)anthryl)phenyl]benzoxazol-5-yl]-l-alanine methyl ester (BoxPhAnt) were studied in a series of solvents. Their absorption spectra are less sensitive to the solvent polarity than the corresponding fluorescence spectra which show a pronounced solvatochromic effect leading to large Stokes shifts. Using an efficient solvatochromic method, based on the empirical solvent polarity parameter , a large change of the dipole moment on excitation for BoxPhAnt has been found. From an analysis of the solvatochromic behaviour of the absorption and fluorescence spectra in terms of bulk solvent polarity functions, f(_r, n) and g(n), a larger excited-state dipole moment (about 8 D, ψ = 56) was obtained for BoxPhAnt than for BoxAnt (about 3 D, ψ = 0). Both applied methods gave similar values of the excited-state dipole moments for both compounds studied.     

Reactions of 1,4-bis(tetrazole)benzenes: formation of long chain alkyl halides

The reactions of 1,4-bis[2-(tributylstannyl)tetrazol-5-yl]benzene with α,ω-dibromoalkanes were carried out in order to synthesise pendant alkyl halide derivatives of the parent bis-tetrazole. This led to the formation of several alkyl halide derivatives, substituted variously at N1 or N2 on the tetrazole ring. The crystal structures of 1,4-bis[(2-(4-bromobutyl)tetrazol-5-yl)]benzene (2-N,2-N′), 1,4-bis[(2-(4-bromobutyl)tetrazol-5-yl)]benzene (1-N,2-N′) and 1,4-bis[(2-(8-bromooctyl)tetrazol-5-yl)]benzene (2-N,2-N′) are reported. Further discussion involves the structure of 1,4-bis[2-(6-bromohexyl)-2H-tetrazol-5-yl]benzene (2-N,2-N′) previously reported.     

Synthesis and absorption-fluorescence properties of

1,4-Bis(²-pyrazolin-3-yl)benzene derivatives were synthesized by the reaction of dibenzal-p-diacetylbenzene or 1,4-bis(-dimethylaminopropionyl)benzene with various hydrazines. Some of these derivatives were converted to the corresponding 1,4-bis(3-pyrazolyl)benzene derivatives by oxidative dehydrogenation with sulfur. The absorption and fluorescence spectra of the synthesized compounds were measured, and the fluorescence quantum yields were determined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 79–83, January, 1980.