The syntheses of several new simple negative, a simple positive, and multiple negative photochromes containing the dihydropyrene-cyclophanediene photochromic system are described. The photo-openings of the negative photochromes, the [e]-annelated benzo (7), naphtho (9), anthro (11), furano (19), and triphenyleno (15) derivatives of the parent 2,7-di-tert-butyl-trans-10b,10c-dimethyl-dihydropyrene (5), as well as its 4,5-dibromo derivative (13), are described to give the corresponding cyclophanedienes, as well as their photoclosures and thermal closures back to the dihydropyrenes. These are compared to the results obtained for the positive photochrome dibenzo[e,l]dihydropyrene (21) and to the bis(dihydropyreno)chrysene (44) and the (dihydropyrenobenzo)(benzo)metacyclophanediene (47) photochromes, which have more than one photochromic switch present and thus have more than a simple "on-off" state. Thermodynamic data are obtained for the thermal closing reactions. The anthrodihydropyrene (12) has the fastest thermal closing (tau(1/2) = 20 min), while the furanodihydropyrene (19') has the slowest (tau(1/2) = 63 h) at 46 degrees C. An electrochemical readout of the state of the switch is demonstrated for the benzodihydropyrene (7). 相似文献
Using a stroboscopic technique, in which the molecule is repeatedly excited and the structural change is probed more than 5000 times per second immediately after excitation, we performed a 16 K time-resolved single-crystal study of the microsecond lifetime triplet state of the Cu(I)phenanthroline derivative[Cu(I)(dmp)(dppe)][PF6] (dppe = 1,2-bis(diphenylphosphino)ethane). The geometry changes on excitation differ for the two symmetry-independent molecules, but are in the same direction as calculated for an isolated reference molecule, although the flattening distortion in the crystal is significantly smaller, implying that the reorganization energy is greatly affected by the confining medium. 相似文献
Treatment of N-(2-mercaptoethyl)-1,8-naphthalimide (HL) with stoichiometric amounts of AsCl(3) and base affords AsL(2)Cl and AsL(3) complexes stabilized in part by secondary As...O bonding interactions. 相似文献
Microwave-assisted desorption (MAD) coupled to in situ headspace solid-phase microextraction (HS-SPME) was first proposed as a possible alternative pretreatment of samples in absorbent collected from workplace monitoring. Aniline collected on silica gel was investigated. Under microwave irradiation, the aniline was desorbed from silica gel and directly absorbed onto the SPME fiber in the headspace. Having been sampled on the SPME fiber, and desorbed in the GC injection port, aniline was analyzed using a GC-FID system. Parameters that affect the proposed extraction efficiency, including the extraction media and its pH, the microwave irradiation power and the irradiation time as well as desorption parameters of the GC injector, were investigated. Experimental results revealed that the extraction of a 150-mg silica gel sample using a 0.8-ml aqueous solution (pH 12) and a PDMS/DVB fiber under medium-high-powered irradiation (345 W) for 3 min maximized the efficiency of extraction. Desorption of aniline from the SPME fiber was optimal at 230 °C held for 3 min. The detection limit was 0.09 ng. The proposed method provided a simple, fast, and organic solvent-free procedure to analyze aniline from a silica gel matrix. 相似文献
A new anthraquinone glycoside, rubiayannone‐A ( 1 ), and a new coumarin, rubilatin‐A ( 2 ), together with twenty‐two known compounds were isolated and characterized from the roots of Rubia ustulata. A new anthraquinone, 2‐carbomethoxyanthraquinone ( 3 ), and rubiayannone‐A, 2‐formylanthraquinone were obtained from the roots of R. yunnanensis. The structures of those compounds were elucidated by spectroscopic methods. The antiplatelet aggregation activity of the isolated compounds 1, 4~6 were also discussed. 相似文献
The preparation of ylides of the general structure is described. Thermolysis of 14a (R = CH3, R' = H, Ar = C6H5) gave dimethylamine and 2,4-dimethyl-6-phenyl-s-triazine. Thermolysis of ylides 14b (R = C6H5; R' = CH3, Ar = C6H5) and 14c (R = C6H5, R' = CH3, Ar = p-tolyl) gave dimethylamine, ArCH = NCH3 and 1-methyl-2-Ar-4,6-diphenyl-1,2-dihydro-s-triazines ( 19a,b ). Triazines 19a and 19b were also prepared by condensation of N-methylbenzamidine with benzaldehyde and p-tolualdehyde, respectively. Thermolysis of 14d (R = C6H5, R1 = CH2C6H5,Ar = C6H5) gave 1-benzyl-2,4,6-triphenyl-1,2-dihydro-s-triazine ( 19c ) and N-benzylidenebenzylamine. Mechanistic aspects of these reactions are discussed. 相似文献
Lithiation of 1,1-bis(phenylthio)-3-phenylthio-1-propene 3 and reaction with a range of electrophiles gave exclusively the γ-substituted product 4. This reagent has been used in a short synthesis of the pheromone, (±)-eldanolide. 相似文献
5‐Methoxy and 5‐anilinopyrido[2,3‐d]pyrimidin‐7(8H)‐ones 2a‐2f were obtained by a tandem Michael addition‐cyclization reaction of methanol and anilines with pyrimidinylpropynoate 5. Methoxy derivative 2a was obtained in 62% yield by treatment of 5 with methanol and potassium carbonate. Anilino derivatives 2b‐2f were prepared in 31–71% yields by reacting 5 with the corresponding anilines in refluxing methanol. This methodology accomplishes Michael‐addition and pyridopyrimidinone ring formation in one‐pot and affords the desired products in reasonable yield without chromatography. Propynoate 5 did not react with 4‐cyanoaniline under these conditions. Reaction of 5 with 2‐aminopyridine gave the unexpected arylpyrido[2,3‐d]pyrimidinone 8 in 58% yield and reaction of 5 with imidazole afforded Michael‐adduct 9 in 69% yield. Compounds 2a and 5 were submicromolar inhibitors of epidermal growth factor receptor (EGFR) tyrosine kinase. 相似文献