We present resonant two-photon ionization (R2PI), IR-UV, and UV-UV double resonance spectra of jet-cooled 2-aminopurine (2AP) as well as Fourier transform infrared (FTIR) gas phase spectra. 2AP is a fluorescing isomer of the nucleobase adenine. The results show that there is only one tautomer of 2AP which absorbs in the wavelength range 32,300-34,500 cm(-1). The comparison with the calculated I...

We have synthesized a highly luminescent (log e > 5.0, F > 0.9) pyrene dye based on a spirobifluorene skeleton [2,2',7,7'-tetrakis(7-tert-butyl-1-pyrenyl)-9,9'-spirobi[9H-fluorene; 4-PySBF]. The use of spirobifluorene prevents fluorescence quenching by intramolecular energy transfer and/or electron transfer among the chromophores in the excited state. The emission spectra of 4-PySBF exhibited a...

The reactions in benzene of 9-alkyl-3-aminocarbazoles with ethyl-3-oxobutanoate yielded ethyl-3-[(9-alkyl-9H-carbazol-3-yl)amino]but-2-enoate condensation products or N-(9-ethyl-9H-carbazol-3-yl)-3-oxobutanamide acylation products. The condensation products were cyclized to the corresponding 4,7-dihydro-pyrido[2,3-c]-carbazol-1-ones upon heating in mineral oil at 240-250 degrees C. The structur...

Cross-conjugated enediynes cannot follow the Bergman cycloaromatization as it involves a methylenediyne moiety with only five pi e(-), insufficient for aromatization. Under reductive conditions the cyclization is made feasible by generating a product with a Hückel number of pi electrons. We illustrate this principle and demonstrate for the first time an anionic cyclization of a cross-conjugated...

The reactivity of different diazoalkane reagents was examined using the coupling reaction with methyl β-Dglucopyranosiduronic acid as a model. 9H-Fluoren-2-yl-diazomethane (FDAM), prepared from its precursor 9H-fluoren2-carbaldehyde hydrazone by MnO2 oxidation, was found suitable as a new labeling agent for carboxyl groups in carbohydrate materials. The reaction with methyl β-D-glucopyranosidur...

In the title compound, C(28)H(21)Cl, the dihedral angle between the two fluorene ring systems is 71.97 (4)°. There is an intra-molecular C-H⋯Cl hydrogen bond. In the crystal structure, the centroid-to-centroid distance between stacked fluorene ring systems is ca 4.22 Å, which indicates that there are no π-π stacking inter-actions between them.

the method cited in the literature for synthesis of 1,2- dihydro 3- thioxo - 1,2,4- benzotriazine 1 was improved .1 was condensed with propargyl bromide to afford 3 - propargylthio – 1,2,4 -benzotriazine 5. transformation of this compound to 9h-3- methylthiazolo [2,3-c] [1,2,4] benzotriazine ( 3, r = me) was performed in the presence of na o me / meoh . orientation of this selective cyclization...