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.     

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.     

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.     

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.     

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.     

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.     

Nitro derivatives of 1-picrylbenzotriazole

The synthesis of the isomeric 4,6-, 5,6-, and 5,7-dinitro-1-picrylbenzotriazoles has been accomplished. The nmr spectra of these compounds and the mononitro derivatives of 1-picrylbenzotriazole were determined and the substituent effects of the nitro and picryl groups on the chemical shifts of the various benzotriazole protons are discussed.     

1,2,5-Thiadiazole 2-oxides: selective synthesis,structural characterization,and electrochemical properties

A new general procedure for the selective synthesis of 1,2,5-thiadiazole 2-oxides (including fused derivatives) 8a,b,c,g,h from the reaction of vic-glyoximes with S₂Cl₂ and pyridine in acetonitrile was elaborated together with general procedure for the synthesis of 1,2,5-thiadiazoles 7a–i, 10, 12, and 14 from the same starting materials and reagents. Molecular structures of 3,4-dimethyl-1,2,5-thiadiazole 2-oxide 8a and [1,2,5]thiadiazolo[3,4-b]quinoxaline 10 were confirmed by single-crystal X-ray diffraction. Electrochemical properties of 1,2,5-thiadiazole 2-oxides 8 were studied by cyclic voltammetry and different behavior was observed for monocyclic and benzo-fused derivatives. With compounds 8g and 17, previously unknown deoxygenation of 2,1,3-benzothiadiazole 1-oxides was discovered by electrochemical reduction, and resulted 2,1,3-benzothiadiazoles 7g and 19 were detected in the forms of their radical anions by EPR spectroscopy combined with DFT calculations.     

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.     

3,4-Phospholanediol 1-oxides and their derivatives

Conclusions Upon reaction of 3,4-epoxyphospholane 1-oxides with alcohols and water in the presence of catalysts having acid character, organic acids, and hydrogen halides, opening of the-epoxide ring occurs with formation of addition products.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2230–2234, October, 1969.     

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.     

N-Lithium derivatives of aliphatic amines in the synthesis of 1-alkyl-2-phenyldiazene 2-oxides

Magnesium derivatives of aliphatic amines containing -hydrogen atoms, in contrast to t-BuNHMgBr, do not form phenylaliphatic diazene oxides upon reaction with nitrobenzene, but rather reduce it to azobenzene and azoxybenzene. Asymmetric diazene oxides are formed when the magnesium derivatives are replaced by lithium derivatives. The reaction of t-BuNHLi with dimethylnitramine gives 1,3,5-trimethyl-1,3,5-triazacyclohexane.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1452–1454, June, 1991.     

Synthesis, characterization, and photovoltaic properties of a low band gap polymer based on silole-containing polythiophenes and 2,1,3-benzothiadiazole

A new low band gap silole-containing conjugated polymer, PSBTBT, was designed and synthesized. Photovoltaic properties of PSBTBT were initially investigated, and an average power conversion efficiency (PCE) of 4.7% with a best PCE of 5.1% was recorded under illumination (AM 1.5G, 100 mW/cm(2)). The response range of the device covers the whole visible range from 380 to 800 nm. These results indicate that PSBTBT is a promising polymer material for applications in polymer solar cells.     

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

The S₁ ← S₀ absorption spectra of 2,1,3-benzothiadiazole (BTD) have been measured at 4.2 K in four different host crystals: naphthalene, durene, p-dichlorobenzene (DCB) and p-dibromobenzene. Detailed vibrational analyses are given for BTD imbedded in napthalene and DCB. The polarization measurements show that the S₁ state has B₂ symmetry, like its selenium analogue (BSD). The transition is dominated by a single totally symmetric mode - 484 cm^?1. The Herzberg-Teller coupling contributes only a very small fraction of the total intensity. The Stark measurements of a DCB sample containing both BTD and BSD enabled us to compare the charge distribution of BTD and BSD in the state S₁. The Stark splittings of BTD are 17% greater than the splittings of BSD. Reorganization of the σ-core during the excitation is used to explain the difference. The drastic change in dipole moment upon excitation implies that the S₁←S₀ transitions of BTD and BSD are not localized in the six-membered ring as suggested by previous workers. Weak phosphorescence of BTD in napthalene and DCB and singlet-triplet absorption spectrum of neat BTD have been observed. The heavy atom effect of spin-orbit coupling is to explain the ST absorption intensity of BTD and BSD.     

The synthesis and reactions of certain pyridazine 1-oxides

Nucleophilic displacement reactions under acidic and basic conditions have been studied with 4,6-dinitro-3-methoxypyridazine 1-oxide ( 1 ) and with 6-chloro-3-methoxy-4-nitropyridazine 1-oxide ( 2 ). Depending on the nature of the nucleophilic reagent and the conditions of the reaction we have found that the chloro group, the nitro group, as well as the methoxy group of 1 and 2 may be displaced by the nucleophile. This type of compound possesses significant in vitro antifungal activity.     

The synthesis of 5-azaindole derivatives via mesoionic oxazolium 5-oxides

A synthesis of 5-azaindole derivatives is described. This synthetic approach involves the preparation of an appropriately substituted pyrrole derivative by a 1,3-dipolar cycloaddition reaction of dimethyl acetylenedicarboxylate with a mesoionic oxazolium 5-oxide. The pyrrole intermediate contains a protected β-aminoethyl substituent, and subsequent removal of the phthalimido protecting group results in cyclization to yield the corresponding 5-azaindole. This approach has been used for both acyclic and cyclic amino acid precursors of the 1,3-dipole which is ultimately used in the sequence.     

An unusual synthesis of 2,3-dihydrophosphindole 1-oxides

A very simple route to dimeric phosphole oxides is reported as is the pyrolytic decomposition of these phosphorus-bridged dimers. Like similar dimeric phosphole sulfides, these phosphole oxide dimers readily eliminate the bridging phosphorus grouping upon strong heating but, unlike the analogous sulfides, hydrogen transfer to give a 2,3-dihydrophosphindole 1-oxide rather than hydrogen elimination to give the fully unsaturated phosphindole oxide occurs. This hydrogen transfer is shown to be non-stereospecific and some mechanistic implications of this are briefly discussed.     

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.