102780-13-2

Upstream product

• 27081-10-3 tropylium tetrafluoroborate 
• 5447-87-0 2-(1-phenylethylidene)propanedinitrile 
• 539-80-0 Tropone 
• 116263-45-7 <2-(2,4,6-Cycloheptatrien-1-yl)-1-phenylethyliden>propandinitril 
• 102780-19-8 3-Methoxy-2-phenyl-3,8a-dihydro-2H-azulene-1,1-dicarbonitrile 
• 102780-24-5 <2-(2,4,6-Cycloheptatrien-1-yliden)-1-phenylethyliden>propandinitril 
• 29647-95-8 2-(cyclohepta-2,4,6-trienyl)-1-phenylethan-1-one 

Downstream Products

• 1417619-45-4 7,8-dibromo-2-phenyl-1,7,8,8a-tetrahydroazulene-1,1-dicarbonitrile 
• 102780-24-5 <2-(2,4,6-Cycloheptatrien-1-yliden)-1-phenylethyliden>propandinitril 
• 1173928-39-6 2-phenylazulene-1,3-dicarbonitrile 

Relevant academic research and scientific papers

Dialkylated Dihydroazulene and Vinylheptafulvene Derivatives – Synthesis and Switching Properties

Functionalization of molecular photoswitches at specific positions offers a way of tuning their switching properties. The work presented here describes the development of a new protocol towards the synthesis and functionalization of the dihydroazulene/vinylheptafulvene (DHA/VHF) photo-/thermoswitch. The key step is a facile condensation reaction using a functionalized tropone derivative, and the new synthetic method was employed in the regioselective preparation of a novel dimethyl-substituted DHA photoswitch. This compound presents the first accessible derivative with alkyl groups on the seven-membered ring of the system ― at positions C5 and C7. From experimental and theoretical kinetics studies on the thermal VHF-to-DHA electrocyclic reaction, the influence of the electron-donating methyl groups was elucidated. In addition, we subjected a small selection of 4,8a-dialkylated compounds to a computational study to elucidate how steric interactions can alter the relative DHA–VHF stabilities. The synthetic methodology offers access to novel DHA scaffolds and substitution patterns, which in turn can lead to systems that can help to address broader questions concerning the potential applicability of the DHA/VHF system in the context of solar-thermal energy-storage systems or other photochromic applications.

Lewis acid enhanced switching of the 1,1-dicyanodihydroazulene/ vinylheptafulvene photo/thermoswitch

Mild Lewis acids enhance the rate of the thermal conversion of vinylheptafulvene (VHF) to dihydroazulene (DHA). In the absence of light, stronger Lewis acids promote the otherwise photoinduced DHA to VHF conversion.

An effective trigger for energy release of vinylheptafulvene-based solar heat batteries

Stoichiometric copper(i) tetrakis(acetonitrile) is found to activate the thermal ring-closure reaction of a series of high-energy vinylheptafulvene isomers to the corresponding low-energy and photoactive dihydroazulenes, allowing the release of energy upon request.

Colorimetric probe for the detection of thiols: The dihydroazulene/ vinylheptafulvene system

A new application of the dihydroazulene/vinylheptafulvene (DHA/VHF) system as a chemodosimeter for thiols is reported herein. A color change visible to the naked eye can be detected in acetonitrile/water (4:1) in the presence of cysteine and alkanethiols but not with other amino acids. The higher reactivity of DHA towards cysteine compared with VHF has been demonstrated. The easy synthesis of the main core and its versatility in terms of structural and physicochemical changes are essential elements for developing a new family of thiol-specific probes with higher selectivity and sensitivity than the reported prototype. Can the dihydroazulene/vinylheptafulvene (DHA/VHF) photo/thermoswitch system be used as a chemodosimeter for thiols? A new application for this versatile system has been discovered.

Dihydroazulene-buckminsterfullerene conjugates

The dihydroazulene (DHA)/vinylheptafulvene (VHF) photo/thermoswitch has recently attracted interest as a molecular switch for molecular electronics. In this field, Buckminsterfullerene, C60, has been shown to be a useful anchoring group for adhering a molecular wire to an electrode. Here we have combined the two units with the overall aim to elucidate how C60 influences the DHA-VHF switching events. Efficient synthetic protocols for making covalently linked DHA-C60 conjugates were developed, using Prato, Sonogashira, Hay, and Cadiot-Chodkiewicz reactions. These syntheses provide as well a variety of potentially useful DHA and C60 building blocks for acetylenic scaffolding. The two units were separated by bridges of various lengths, such as oligo(phenyleneethynylene) (OPE2 and OPE3) wires. The distance of separation was found to influence strongly the light-induced ring-opening reaction of DHA to its corresponding VHF. Thus, C60 was found to significantly quench this conversion when situated closely to the DHA unit.

Optimized synthesis and detailed NMR spectroscopic characterization of the 1,8a-dihydroazulene-1,1-dicarbonitrile photoswitch

An economical and effective protocol for large scale synthesis of the 2-phenyl-1,8adihydroazulene-1,1-dicarbonitrile (DHA) photoswitch has been developed. This compound is ring-opened by light to a vinylheptafulvene (VHF), which is thermally closed back to DHA. This compound serves as an important starting material for dihydroazulene photoswitches incorporating a substituent in the seven-membered ring and as a reference compound for comparison of properties. A detailed NMR spectroscopic characterization has allowed the assignment of all proton and carbon signals. In addition, the compound was characterized by Xray crystallography. A correlation between the rate constant for thermal ring-closure of VHF to DHA and empirical parameters of solvent polarity (ET (30)) was established. ARKAT-USA, Inc.

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.

NOVEL MULTICHROMOPHORIC DYES FOR CHEMICAL AND PHYSICAL SWITCHING

Functionalized photochromic compounds and their applications in chemical and physical switching processes are under investigation.In this report exclusive consideration is given to the dihydroazulene (DHA)/vinylheptafulvene (VHF) system 1/2.A short description of the photochromism of 1/2 is presented.Three topics of potential switching behaviour released by the photochromism of 1/2 are pointed out: (i) change of the pKa and of proton transfer properties in anilinium derivatives, (ii) change of the redox potential in compounds with electron transfer active subunits, (iii) increase of second-order nonlinear optical properties by irradiation of 1.

Light-Sensitive Dihydroazulenes: Alternative Synthesis - The Influence of Alkyl Substituents at the Five-Memeered Ring on the Photochromic Behaviour

Starting from cycloheptatrienylium tetrafluoroborate (8) the dihydroazulenes 1 were synthesized via substituted cycloheptatrienes 10 - 13 as intermediates.The dicyanovinyl derivatives 12 and 13 were transformed into vinylheptafulvenes 2 by dehydrogenation

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.