Sergei Fomine

Thermal Reactions of Aromatic Diacetylenes: An Insight to Amorphous State Polymerization of Diacetylenes

Several aromatic diacetylenes were heated in molten state, and the formation of diradicals was studied by ESR spectroscopy. Intense ESR signals were observed even at temperatures as high as 180°C. The formation of radical species at such low temperatures was explained by the formation of oligomeric species. The numbers of unpaired electrons in the molten state reached to 1021 electrons per mole of diacetylene, when heated to 180°C, and deep red materials were obtained. Surprisingly the radicals did not disappear when exposed to air showing that the radicals are stable in air.

Charge transfer complexes between 4,4′-disubstituted diphenyldiacetylenes: experimental and theoretical study

Abstract Novel charge transfer (CT) complexes containing donor and acceptor derivatives of diphenyldiacetylene have been synthesised and characterised. The structure of CT complexes was modelled at the B3LYP/6-31G(d)//B3LYP/6-31G(d) level of theory. It was found that the complex formation is mainly due to dipole–dipole interaction between side groups of diacetylene molecules and there was no significant charge transfer between donor and acceptor in the ground state. On the other hand, optical excitation of CT complexes leads to strong charge transfer from donor to acceptor molecule as followed from the modelling using time-dependent density functional theory (DFT) method. Diacetylene molecules adopt strongly bent configuration in CT complexes which is prohibitive for solid-state topochemical polymerisation of diacetylenes

Studies on diacetylenic vinyl compounds

SummaryThree alka-3,5-diynylmethacrylate and 1,8-Bis(methacryloxy)octa-3-5-dyine were synthesized and their polymerization in the molten state was studied. 3,5-Octadiynylene-1,8-dimethacrylate, which was the only one that was solid at room temperature, was not light sensitive in the solid state. All the monomers underwent rapid polymerization at 140 °C. The DSC and IR-spectra indicated that the polymerization of the vinyl and diacetylenic groups takes place simultaneously. An optically highly transparent, yellow-orange glass was obtained.

Third order nonlinear optical susceptibility of films of polydiacetylene-containing polyamides and polyesters

SummaryThe third order nonlinear optical susceptibilities of cast films of diacetylene-containing polyamides, copolyamides and polyesters, were measured using degenerate four-wave mixing with picosecond pulses at 532 nm. The blue films of polyamides which contain aromatic polydiacetylene had χ(3) values of the order of 10-9–10-10 esu, while the orange films of polyesters having aliphatic polydiacetylenes showed χ(3) values of the order of 10-10–10-11 esu.

Unusual behaviour of bis[ω-hydroxyalkyl]-1,8,4,5-naphthalenetetracarboxylic bisimides in bisimide–lactam ring contraction: experimental and theoretical study

Abstract A series of novel [ω-hydroxyalkyl]-1,8,4,5-naphthalenetetracarboxylic bisimides has been synthesised and tested in the bisimide–lactam ring contaction reaction. It was found that N , N ′-bis[ω-hydroxyalkyl]-1,8,4,5-naphthalenetetracarboxylic bisimides with short methylene spacer show unusually low reactivity in bisimide–lactam ring contraction reaction common for six-membered bisimides. The molecular modelling results shows that the reason for such a behaviour is deprotonation of one of the hydroxy groups of bisimides destabilising tetrahedral intermediate — the key intermediate in the ring contraction reaction.