The polarized electronic spectra and electric field spectra of benzo-diazoles. I. 2,1,3-benzoselenadiazole

The analyses of the polarized spectra of the S₁ - S_o transition of 2,1,3-benzoselenadiazole (BSD) dispersed in two different host crystals: naphthalene and p-dichlorobenzene have yielded (1) the assignment of the S₁ state as B₂, and (2) the vibronic coupling activity by b₂ fundamentals. VibronicaUy induced intensity by b₂ fundamentals accounts for only a small fraction of the overall intensity, but the intensity of phonon sidebands amounts to about 80% of the total intensity. The phosphorescence spectrum and the singlet-triplet absorption have been observed. Electric field spectra have been used to (1) measure the change of dipole moments upon excitation: 1Δμ(S₁ - S_o)I = 3.35 D and IΔμ(T₁- S_o) I = 2.26 D, (2) establish the identity of low frequency bands (19 - 111 cm^?1) as phonon sidebands, and (3) probe the nature of vibronic activity.     

The 13C NMR spectra and structure of 2,1,3-benzoxadiazole,-benzothiadiazole and -benzoselenadiazole

The ¹³C NMR chemical shifts and one-bond carbon–hydrogen coupling constants have been obtained for the title compounds in carbon disulphide as solvent. There appears to be little solvent effect on the ¹³C chemical shifts. The results suggest the order of release of electrons into the ring is O ? S > Se.     

Monoximes and dioximes of 2,1,3-benzothiadiazole dignes

NMR spectra, in organic solvents, and dissociation constants in water, have been determined for a series of monoximes, dioximes and mono-O-methyldioximes of 2,1,3-benzothiazole-4,5 and 4,7-dione. On the basis of NMR data “4 - hydroxy - 5 - nitroso-, 4 - hydroxy - 7 - nitroso- and 5 - hydroxy - 4 - nitroso -2,1,3- benzothiadiazole” exist predominantly in quinonemonoxime forms. Configurations were assigned to geometrical isomers. The 4,5- and 4,7 - di - O - methyidioximinobenzothiadiazoles were also investigated. Four and two geometrical isomers of the 4,5- and 4,7-derivatives, respectively, have been separated, and the physical and spectral properties of each isomer are described.     

Energetic and structural properties of 4-nitro-2,1,3-benzothiadiazole

The energetic study of 4-nitro-2,1,3-benzothiadiazole has been developed using experimental techniques together with computational approaches. The standard (p^° = 0.1 MPa) molar enthalpy of formation of crystalline 4-nitro-2,1,3-benzothiadiazole (181.9 ± 2.3 kJ · mol⁻¹) was determined from the experimental standard molar energy of combustion −(3574.3 ± 1.3) kJ · mol⁻¹, in oxygen, measured by rotating-bomb combustion calorimetry at T = 298.15 K. The standard (p^° = 0.1 MPa) molar enthalpy of sublimation, at T = 298.15 K, (101.8 ± 4.3) kJ · mol⁻¹, was determined by a direct method, using the vacuum drop microcalorimetric technique. From the latter value and from the enthalpy of formation of the solid, it was calculated the standard (p^° = 0.1 MPa) enthalpy of formation of gaseous 4-nitro-2,1,3-benzothiadiazole as (283.7 ± 4.9) kJ · mol⁻¹. Standard ab initio molecular orbital calculations were performed using the G3(MP2)//B3LYP composite procedure and several working reactions in order to derive the standard molar enthalpy of formation 4-nitro-2,1,3-benzothiadiazole. The ab initio results are in good agreement with the experimental data.     

The polar nature of 2,1,3-benzoxadiazole, -benzothiadiazole, -benzoselenadiazole and derivatives as determined by their electric dipole moments

Permanent electric dipole moments have been determined in benzene solutions at 25° for the oxygen, sulfur, and selenium series of 2,1,3-benzodiazoles. The derivatives studied contained 4, 5, and 6 substituted methyl, chloro, nitro, and amino groups. The dipole moment data of the derivatives were analyzed relative to that of the parent species which allowed deductions to be made about the mesomeric structures operating in the compounds. The mesomeric charge transfer increases regularly from the oxygen to the selenium structures, being nearly undetected in 2,1,3-benzoxadiazole derivatives and very pronounced in the 2,1,3-benzoselenadiazoles.     

芴-呋喃苯并噻二唑共聚物的光电性能

对芴-呋喃苯并噻二唑共聚物的吸收光谱、光致发光光谱、电致发光性能和光伏性能进行了研究. 共聚物在382 nm和530 nm处有两处明显的吸收峰, 其中530 nm处的吸收强度随着共聚物中呋喃苯并噻二唑单元(FBT)含量的增加而增加. 随着FBT单元含量的增加, 电致发光峰值从611 nm红移至702 nm. 以PVK为空穴传输层, 共聚物PFO- FBT0.1为发光层的发光器件, 在33 mA/cm2电流密度下的外量子效率达2.32%, 亮度为441 cd/m2. 实验中观察到快速的链内能量陷阱过程(从芴到FBT单元). 以共聚物PFO-FBT50为电子给体、PCBM为电子受体(重量比1:2)共混制备的光电池能量转换效率为1.13%, 开路电压0.85 V, 短路电流3.39 mA/cm2, 光谱响应边延伸至近750 nm.     

EPR measurements of the phosphorescent state of 2,1,3-benzothiadiazole

The spin dipolar interaction and the hyperfine structure of the phosphorescent state of 2,1,3-benzothiadiazole have been measured in a naphthalene host crystal at 77 K. Preliminary transient study indicates the short in-plane spin substate is the active component in the triplet population.     

Optoelectronic properties of fluorene-co-4,7-difuran-2,1,3-benzothiadiazole copolymers

Light-emitting and photovoltaic properties of copolymers(PFO-FBT) based on 9,9-dioctylfluorene and 4,7-difuran-2,1,3-benzothiadiazole(FBT) units were investigated.The copolymers show two absorbance peaks at around 382 nm and 530 nm,respectively.The relative absorbance at around 530 nm of the PFO-FBT copolymers increases with the increasing FBT content.The EL emissions are red-shifted from 611 nm to 702 nm by increasing the FBT content in the copolymer.The highest EL external quantum efficiency ach...     

Investigation of thermal and luminescent properties in 4,7-diphenylethynyl-2,1,3-benzothiadiazole systems

A series of luminescent liquid crystals based on 4,7-diphenylethynyl-2,1,3-benzothiadiazole system was prepared and characterised. The molecules were planned varying number, length and position of the linear alkoxy/thioalkyl chains. Their mesomorphic properties were studied by differential scanning calorimetry, polarised optical microscopy and X-ray diffraction. The liquid crystalline properties were found to be dependent on the length, position and number of the peripheral alkoxy chains. It was observed preferentially smectic C and nematic phases whose stability increase with the elongation of the peripheral portion. Photophysical studies were performed in chloroform solution. These compounds displayed strong yellow photoluminescent properties in the visible region, with absorption patterns peaking around 400–450 nm and emission between 500–610 nm with good quantum yields. Also, solvatochromism studies were performed.     

The mass spectra of some 2,1,3-benzothiadiazoline and 2,1,3-benzothiadiazine 2,2-dioxides

Although the behaviour of 1H, 2H-2,1,3-benzothiadiazoline 2,2-dioxide is similar to that of sulphoxides in the mass spectrometer in losing a molecule of SO₂, the 1,3-dimethyl derivative loses the radical SO₂H. In addition the radical CH₃SO₂ is lost in a one step process that must involve a methyl migration. The radical SO₂H is also lost from 2,1,3-benzothiadiazine 2,2-dioxides methylated in the 3-position and the hydrogen involved is shown to originate from this methyl group by deuterium labelling. The mass spectra of other 2,1,3-benzothiadiazine 2,2-dioxides are also discussed.     

Reduced-size polarized basis sets for calculations of molecular electric properties. II. Simulation of the Raman spectra

The accuracies of the calculated vibrational frequencies and Raman intensities given by two new, highly compact Pol-type basis sets, Z2PolX and Z3PolX, have been determined and compared to the 6-31G(d), PolX, and aug-cc-pVTZ basis sets. Calculation of accurate Raman intensities has previously required large basis sets, but the ZmPolX basis sets are smaller even than PolX, which are the most compact basis sets able to calculate accurate Raman intensities. For the largest compound studied, C5H10O2, Z3PolX required more than an order of magnitude less CPU time than PolX, which has been shown to be 10 times faster than aug-cc-pVTZ. Two sets of test molecules were studied: one was a series of small molecules for which experimental values for absolute Raman activities were available; the second was a series of medium-sized molecules (mainly common organic solvents) where only relative Raman band intensities were available. The accuracies of the Raman intensities given by both of the ZmPolX basis sets were good compared to those of the PolX and aug-cc-pVTZ sets, and much better than the 6-31G(d) values. The errors in even unscaled frequency values <2000 cm(-1) were also acceptable and were slightly lower for Z3PolX than Z2PolX (30 cm(-1) vs. 48 cm(-1)). The combination of good intensity and frequency data meant that for the medium-sized organic molecules there was a close correspondence between the simulated Raman spectra and experimental data, and that the observed bands could easily be assigned on the basis of these calculations. Achieving this level of accuracy in the simulations at modest computational cost should now allow computational methods to be combined with experimental Raman studies much more widely than is currently the case.     

Recent progress of electronic materials based on 2,1,3-benzothiadiazole and its derivatives: synthesis and their application in organic light-emitting diodes

2,1,3-Benzothiadiazole(BT) and its derivatives are very important acceptor units used in the development of photoluminescent compounds and are applicable for the molecular construction of organic light-emitting diodes, organic solar cells and organic field-effect transistors. Due to their strong electron-withdrawing ability, construction of molecules with the unit core of BT and its derivatives can usually improve the electronic properties of the resulting organic materials. In this contribution, we review the synthesis of various polymers, small molecules and metal complexes with BT and its derivatives and their applications in organic light-emitting diodes. Furthermore, the molecular design rules based on these cores are discussed.     

The infrared spectra and structure of 2,1,3-benzoselenadiazoles

The IR spectra of twentysix 2,1,3-benzoselenadiazoles have been recorded and analysed. Tentative assignments of the characteristic bands have been made by analogy with other benzoheterocycles. The data obtained do not permit any conclusion to be drawn concerning the fine structure of 2,1,3-benzoselenadiazoles.     

Poly(4-amino-2,1,3-benzothiadiazole) films: preparation,characterization and applications

The electrochemical preparation of novel poly(4-amino-2,1,3-benzothiadiazole) films on a platinum surface in sulfuric aqueous medium by cyclic voltammetry is described. The resulting polymeric electrodes were characterized by FT Raman spectroscopy, scanning electron microscopy and potentiometry. Spectroscopic measurements confirmed the participation of the amino group and sulfur atom in the process that forms the granular structure of poly(ABTD). Potentiometric results showed the response of the poly(ABTD) film towards divalent cations such as Zn²⁺ and Cd²⁺ in the concentration range from 10^?7 up to 10^?2 mol L^?1. A cooperative combination of the cation-sensitive poly(ABTD) electrodes in an array with pH- and anion-sensitive electrodes was able to recognize different Czech beers.     

Investigations in the field of 2,1,3-thiadiazole and 2,1,3-selenadiazole

The action of sodiomalonic ester on 4-bromomethylbenzo-2,1,3-thiadiazole forms a malonate which is converted by acid hydrolysis into 4-(-carboxyethyl)benzo-2,1,3-thiadiazole. When this reaction is carried out with 5-bromomethylbenzo-2,1,3-thiadiazole, mono- and disubstituted malonic esters are formed the acid hydrolysis of which gives the corresponding acids. The nitration of 4-and 5-(-carboxyethyl)benzo-2,1,3-thiadiazoles forms, respectively, 4-(-carboxyethyl)-5,7-dinitrobenzo-2,1,3-thiadiazole and 5-(-carboxyethyl)4-nitrobenzo-2,1, 3-thiadiazole. The reaction of 4-bromomethylbenzo-2,1, 3-thiadiazole with potassium cyanide forms two products: 4-cyanomethylbenzo-2,1, 3-thiadiazole and 1,2-di(benzo-2,1, 3-thiadiazole-4-yl)-2-cyanoethane.For part LVIII, see [1].     

聚苯撑乙炔-苯并噻二唑共聚物的合成及光谱性能

利用钯催化剂[Pd(PPh₃)₂Cl₂]和相转移催化剂(PTC), 采用Heck交叉偶联缩聚反应合成了聚(苯撑乙炔撑-苯并噻二唑)系列交替共聚物(PPE-BT), 比较了聚合物的紫外吸收光谱和荧光光谱特征.     

Theoretical study of the polarized electronic absorption spectra of vanadium-doped zircon

The polarized electronic absorption spectra of a blue vanadium-doped zircon single crystal, grown by the flux method, has been studied by quantum chemical (CI) calculations in order to determine the position of the V⁴⁺ dopant in the zircon host structure. Particularly, the excitation energies and polarizations of V⁴⁺ occupying alternate positions, either the zirconium or silicon position or the interstitial site 16g, have been considered. It is concluded that the observed electronic absorption spectra and the color of zirconblue can only be explained if the V⁴⁺ chromophore is placed on the respective interstitial position.     

Highly emissive dimesitylboryl-substituted 2,1,3-benzothiadiazole derivatives: photophysical properties and efficient fluorescent sensor for fluoride anions

One symmetrical and two unsymmetrical dimesitylboryl-substituted BTD derivatives 1–3 were prepared through Pd(0)-catalyzed Suzuki coupling reaction. All these compounds display intense fluorescence not only in solution but also in the solid state due to steric bulkiness of the boryl group, which is effective to suppress the intermolecular interactions in the solid state. In addition, the boryl-substituted BTD 1 displays prompt fluorescence responses to fluoride ions with high sensitivity through the complexation of the boron center with fluoride, demonstrating its potential utility as fluorescent sensor for fluoride ions.     

Nitro derivatives of 2,1,3-benzothiadiazole 1-oxides: synthesis,structural study,and NO release

A convenient one-pot synthesis of nitro derivatives of 2,1,3-benzothiadiazole 1-oxides by the reaction of o-nitroanilines with sulfur monochloride was developed. The structural features of 4-nitrobenzothiadiazole and its N-oxide were considered. High in vitro release of nitric oxide (69%) was found for a 6-nitro-2,1,3-benzothiadiazole sample by the Griess assay, which indicated good prospects for this class of compounds.     

Drift of spiral waves controlled by a polarized electric field

The drift behavior of spiral waves under the influence of a polarized electric field is investigated in the light that both the polarized electric field and the spiral waves possess rotation symmetry. Numerical simulations of a reaction-diffusion model show that the drift velocity of the spiral tip can be controlled by changing the polarization mode of the polarized electric field and some interesting drift phenomena are observed. When the electric field is circularly polarized and its rotation follows that of the spiral, the drift speed of the spiral tip reaches its maximal value. On the contrary, opposite rotation between the spiral and electric field locks the drift of the spiral tip. Analytical results based on the weak deformation approximation are consistent with the numerical results. We hope that our theoretical results will be observed in experiments, such as the Belousov-Zhabotinsky reaction.