The results of studies on intramolecular interconversions in systems of norbornadiene quadricyclane and their derivatives are classified and discussed. The mechanisms of the forward photoreaction and reverse thermal process in relation to the nature of the substituents and carbocycles, type of sensitiser and catalyst, and properties of the medium are discussed in detail and classified. An analysis is made of the influence of these factors on the spectroscopic, kinetic, and thermodynamic properties of this system as an accumulator and converter of light energy. Methods of improving its characteristics — light absorption, the quantum yield of the photoreaction, and stability of the photoproduct — have been established. The bibliography includes 188 references.

https://iopscience.iop.org/article/10.1070/RC1991v060n05ABEH001088/pdf

Norbornadiene-quadricyclane — an effective molecular system for the storage of solar energy

Four copper(I) complexes have been designed as photosensitizers for assisting the norbornadiene (NBD) → quadricyclene (Q) isomerization with the purpose of carrying out the reaction using visible light and achieving a high NBD/photocatalyst turnover. All complexes contain π-delocalized bidentate N⌒O monoanionic ligands. Their syntheses have been performed either by the metathesis reaction from CuCl or by reaction of the monoprotic ligands with Cu5Mes5 (Mes ≡ 2,4,6-Me3C6H2) in the presence of norbornadiene. The dinuclear complexes [Cu2L2(μ-NBD)], 3, [Cu2L‘2(μ-NBD)], 4, [Cu2L‘‘2(μ-NBD)], 5, and [Cu2L‘‘‘2(μ-NBD)], 6 [where L = 2-methyl-8-oxoquinolinato, L‘ = 2-methyl-5,7-dichloro-8-oxoquinolinato, L‘‘ = 4-oxoacridinato, and L‘‘‘ = 2-(2-oxo-3,5-di-tert-butyl phenyl)benzotriazole], have been isolated and characterized in the solid state, including the X-ray analysis on 3 and 6. All compounds show absorption in the visible spectrum, due to the presence of metal-to-ligand charge-transfer (MLCT) bands. Most were ...

Designing Copper(I) Photosensitizers for the Norbornadiene−Quadricyclane Transformation Using Visible Light: An Improved Solar Energy Storage System

N,N'-Bis[(3-carboxynorbornadien-2-yl)carbonyl]methylenedianiline (BNMA) was synthesized in 87 % yield by the reaction of 2,5-norbornadiene-2,3-dicarboxylic acid anhydride with 4,4'-methylene-dianiline. Other dicarboxylic acid derivatives containing norbornadiene (NBD) residues were also prepared by the reaction of 2,5-NBD-2,3-dicarboxylic acid anhydride with certain diamines. When the polyaddition of BNMA with bisphenol A diglycidyl ether (BPGE) was carried out using tetrabutylammonium bromide as a catalyst in NMP at 100 °C for 24 h, a polymer with a number average molecular weight of 18 000 was obtained in 91% yield. Polyadditions of other NBD dicarboxylic acid derivatives with BPGE were also performed under the same conditions. The reaction proceeded very smoothly to give the corresponding NBD poly(ester-amide)s in good yields. Furthermore, the photochemical reactions of the NBD poly-(ester-amide)s were evaluated in the film state or in solution. The photochemical valence isomerization of NBD residues in the polymer films proceeded smoothly to form the corresponding quadricyclane (QC) groups upon irradiation with sunlight. The photochemical reversion of the resulting QC groups in the polymer films proceeded efficiently by irradiation of 272 nm light. The stored energy in the QC groups of the polymers was evaluated to be about 84 kJ/mol by DSC measurement of the irradiated polymer films.

Synthesis of Poly(ester−amide)s Containing Norbornadiene (NBD) Residues by the Polyaddition of NBD Dicarboxylic Acid Derivatives with Bis(epoxide)s and Their Photochemical Properties

2,3-Dipyridylnorbornadienes were prepared using the Diels–Alder reaction of the HBF4 salts of dipyridylacetylenes with cyclopentadiene. Their absorptions extend to 380 nm and are red-shifted in an acidic media. They underwent photocyclization to give quadricyclanes which reverted to norbornadienes upon heating or encountering a Co(II)–TPP catalyst. 2,3-Bis(1-methylpyridinio)norbornadienes were also prepared by a Diels–Alder reaction of bis(1-methylpyridinio)acetylenes with cyclopentadiene. Irradiation of 1-methyl-2-pyridinio and 1-methyl-3-pyridinio derivatives led to the photostationary state between them and the corresponding quadricyclanes, while a 1-methyl-4-pyridinio derivative gave a water or methanol adduct in the presence of water or methanol. Electron-transfer reactions of bis(1-methylpyridinio)norbornadienes were investigated by cyclic voltammetry. The radical cations formed by their reduction were unstable compared with those of the corresponding trans-bis(1-methylpyridinio)ethylenes. Steric fa...

Syntheses and Properties of Dipyridylnorbornadienes

Synthesis of Methyl 6,6-Dimethylfulvene-2-carboxylate and Dimethyl 6,6-Dimethylfulvene-2,3-dicarboxylate as well as their Reaction to 2,3,5,6-Substituted Norbornadienes



Fulvenes 5 and 6 were synthesized by Diels-Alder reaction of 6,6-dimethylfulvene with methyl prop-2-ynoate and dimethyl but-2-ynedioate, catalytic reduction of the unsubstituted norbornadiene double bond, and a subsequent retro Diels-Alder reaction under flash vacuum pyrolysis conditions, 5 and 6 are used as the diene component in synthesizing 2,5-, 2,3,5-, and 2,3,5,6-substituted norbornadienes 7–9 by Diels-Alder reaction with electron-deficient alkynes.

Synthese von 6,6‐Dimethylfulven‐2‐carbonsäure‐methylester und ‐2,3‐dicarbonsäure‐dimethylester sowie deren Umsetzung zu 2,3,5,6‐substituierten Nordbornadienen

Photoisomerization of 3-(aryicarbamoyl)norbornadiene-2-carboxylic acid 1 to the corresponding quadricyclane derivative 2 in an aqueous alkaline solution was clean and dependent upon the p-substituent of the aryl group. The exothermically reversal reaction of 2 to 1 was also clean but independent upon the substituent.

Tetsuya Yanai

Papers

Valence Isomerization between Water-soluble Norbornadiene and Quadricyclane Derivative