The quinoidal versus biradicaloid character of the ground state of a series of thiophene‐based heterophenoquinones is investigated with quantum‐chemical calculations. The role of the ground‐state electronic character on molecular structure and vibrational properties is emphasized. The vibrational activities are experimentally determined and their analysis is performed by taking advantage of the definition of a collective vibrational coordinate (the
Shifts for crystals : Solid‐state NMR spectroscopy can be used for structure determination of microcrystalline paramagnetic solids at natural isotopic abundance. The protocol makes use of paramagnetic effects, measured on suitably recorded 1H NMR spectra, to define the conformation of a molecule in the lattice and the intermolecular packing in the solid phase. The method is illustrated with a family of lanthanide compounds (see picture).
A synthesis of N‐alkyl‐4‐chloro‐1H‐benzo[c][1,2]thiazine‐3‐carbaldehyde‐2,2‐dioxides is described. Reactivity of new β‐chloroaldehydes is investigated, a number of novel benzo[c][1,2]thiazine derivatives are synthesized and characterized using 1H, 13C‐NMR, MS and elemental analysis. 相似文献
By the reaction aminomethylation, chloromethylation and acylation of 4‐methyl‐4H‐1,2,4‐triazole‐3‐thiol, 4‐methyl‐1‐substituted‐1H‐1,2,4‐triazole‐5(4H)‐thione 1‐8 were obtained. Molecular structure of the obtained compounds was confirmed by an elemental analysis, IR, 1H NMR and 13C NMR spectra and additionally by X‐ray analysis for 2. Six new compounds 1,2,4‐7 were tested for antibacterial activity against Mycobacterium smegmatis, Mycobacterium phlei and avirulent strain Mycobacterium H37Ra. 相似文献
Simple alkylation of 5‐(aminodialkyl)methylcytosine a‐d gives twelve new, potentially biologically active 1N o‐(m‐ or p‐) bromobenzyl derivatives of 5‐substituted cytosine 1‐12 with high regioselectivity. The structures of all compounds have been confirmed by elemental analysis, IR, 1H NMR and 13C NMR spectroscopic measurements. 相似文献
On an atomic scale and with high sensitivity, solid‐state NMR spectroscopy can provide information about the electronic spin density and coupling mechanisms in paramagnetic compounds. The picture shows how the hyperfine splitting collapses through relaxation. Insights into which compounds are suitable and which approximations have to be made are given.
Under acetylating conditions racemic thioflavanone thiosemicarbazones cyclize into racemic 3‐acetyl‐spiro[1,3,4‐thiadiazoline‐2,4′‐thioflavans] and a racemic 3‐acetylspiro[1,3,4‐oxadiazoline‐2,4′‐thioflavan] with trans O(1) or S(1) and Ph(2′eq). Hindered rotation of the endocyclic N(3) acetyl group spirothia‐diazolines caused the formation of isomers separable by HPLC. X‐ray diffraction analyses, 1H‐, 13C‐, and 15N NMR measurements as well as MOPAC QM calculations were performed to reveal the structures of these isomers. 相似文献
3,4‐Dihydroxy‐2‐quinolin‐2‐ylpyrido[3,2,1‐jk]carbazol‐6‐ones 6 were obtained by cyclocondensation of carbazole 1 with malonates 2 in the presence of quinoline. The assignment of the structures of 6 was performed by NMR experiments such as 1D 1H, 13C and DEPT, as well as 2D COSY, HSQC, HMBC and 1,1‐ADEQUATE spectra. 相似文献
A series of 3‐[(6‐chloropyridin‐3‐yl)methyl]‐6‐substituted‐6,7‐dihydro‐3H‐1,2,3‐triazolo[4,5‐d]pyrimidin‐7‐imines were designed and synthesized via a multi‐step sequence using 2‐chloro‐5‐(chloromethyl)‐pyridine as the starting material. Various primary aliphatic amines, hydrazine and hydrazide reacted with 3 to obtain the cyclization products 4 . Their structures were confirmed by 1H NMR and elemental analyses, some of them were also confirmed by IR, 13C NMR, MS and single crystal X‐ray diffraction. The preliminary bioassay indicated that some of the target compounds 4 displayed moderate to weak fungicidal activity and insecticidal activity. 相似文献
Synthesis of some novel 2‐{2‐[1‐(3‐substitutedphenyl)‐1H‐1,2, 3‐triazol‐4‐yl‐]ethyl)‐1H‐benzo[d]‐imidazole derivatives, by the condensation of o‐phenylenediamine with 3‐(1‐(3‐substituted‐phenyl)‐1H‐1,2,3‐triazol‐4‐yl) propanoic acid and then subsequent reactions with different substituted alkyl halides as electrophiles are mentioned. The synthesized compounds were characterized by 1H NMR, EI‐MS and IR spectroscopic techniques. 相似文献
5‐Aryl‐3,4‐diamino‐1,2,4‐triazoles 5 on treatment with β‐chlorocinnamaldehydes 7 in the presence of catalytic amount of p‐TsOH and N,N‐dimethylformamide as an energy transfer medium under microwave irradiation and as solvent with oil‐bath heating at 80 °C affords novel 3,6‐diaryl‐5H‐[1,2,4]triazolo[4,3‐b]‐1,2,4]triazepines 8 . The structures of the synthesized compounds were established on the basis of 1H NMR, IR, mass spectral data and elemental analysis. 相似文献
A series of 2‐(3‐(trifluoromethyl)‐5‐(alkoxy)‐1H‐pyrazol‐1‐yl)‐4‐aryloxypyrimidine derivatives were designed and synthesized. The structures of all the title compounds were confirmed by 1H NMR and elementary analysis. These compounds were screened for herbicidal activity against rape and barnyard grass. Compound B13 exhibited moderate herbicidal activity. 相似文献