102780-23-4

Upstream product

• 102780-18-7 2-(4-Bromo-phenyl)-3-methoxy-3,8a-dihydro-2H-azulene-1,1-dicarbonitrile 
• 102780-12-1 2-(4-bromophenyl)-1,8a-dihydroazulene-1,1-dicarbonitrile 

Downstream Products

• 102780-12-1 2-(4-bromophenyl)-1,8a-dihydroazulene-1,1-dicarbonitrile 

Relevant academic research and scientific papers

Dihydroazulene/Vinylheptafulvene Photochromism: Effects of Substituents, Solvent, and Temperature in the Photorearrangement of Dihydroazulenes to Vinylheptafulvenes

1,1-Dicyano-2-phenyl-1,8a-dihydroazulene (H-D) and a series of p-phenyl-substituted derivatives (R-D, R: NO2, CN, Br, Cl, CH3, OCH3, and NH2) were investigated by time-resolved and steady-state photochemical methods.The dihydroazulenes (DHAs) undergo an efficient photoreaction to the corresponding vinylheptafulvenes (VHFs), the quantum yield (ΦD->V) at room temperature ranges from 0.1 to 0.6.The VHFs (λV = 440-470 nm) are nonemitting and photochemically nonreactive and undergo a thermal rearrangement.The activation energy for this back-reaction is 18-21 kcal/mol.The A factor is in the (0.01-5) * 1010 s-1 range; it varies with substituent and increases with increasing solvent polarity.The photoproduct is formed via a singlet pathway, 1DHA* -> VHF; triplet states are not involved in this reaction.Fluorescence from the DHAs was observed, weakly in fluid solution and most efficiently in glasses at low temperatures (e.g., λf ca. 480 nm for the parent compound).The quantum yield (Φf) at -196 deg C ranges from 0.15 to 0.9.A transient (λmax ca. 450 nm, τT D->V is strongly retarded, the triplet is observable on direct excitation with a lifetime of less than 10 μs even at -196 deg C.The increase of Φf and the reverse effect for ΦD->V with decreasing temperature indicates competition of these processes due to an activation barrier (1DHA* -> VHF pathway.Characteristic features of the ground-state and first excited singlet energy surfaces are presented.

Light-Induced and Reversible Transformations: Syntheses and Properties of Photochromic 1,1-Dicyano-1,8a-dihydroazulenes and Thermochromic 8-(2,2-Dicyanovinyl)heptafulvenes

1,1-Dicyano-2-aryl-1,8a-dihydroazulenes 6(a-g) are prepared in a two-step synthesis starting from 8-methoxyheptafulvene and benzylidenemalononitriles via the tetrahydroazulenes 5.The compounds 6(a-h) rearrange to 8-(2,2-dicyano-1-arylvinyl)heptafulvenes 7(a-h) by irradiation with visible light.The back reaction of 7 to 6 occurs under thermal conditions.Donor-substituted compounds indicate higher long term stability of the equilibrium 6 7 (6f 7f > 44 h).Spectroscopic data of 6 and 7 are given.The molecular structures of the p-bromophenyl derivative 6c and of the p-methoxyphenyl derivative 7f are revealed through crystallography.Some results for the rearrangements 6 7 in the solid state are given.