ChemInform Abstract: PHOTOINITIATED ACYLOTROPIC REARRANGEMENT TO A SERIES OF ACYLATED IMINES OF 3‐OXOBENZO(B)THIOPHENE‐2‐CARBOXYALDEHYDE

Abstract

Bei Bestrahlungen von Lösungen der N‐Acylverbindungen (I) im Frequenzbereich der längerwelligen Absorptionsbande entstehen die O‐Acylderivate (III).

Crystalline and molecular structure of photochromic 2-(N-Acetyl-N-3-NitrophenylaminomethyIene)3-3(2 H)- Benzo[b]-Thiophenone and its photoinitiated acylotropic rearrangement product

“…The structures were solved by direct methods from diffractometer data measured with CuA^a radiation and refined to final R indexes of 0.045 for the 955 observed terms for (I) and (II), respectively. The possible mechanisms of photochromic reactions are discussed.Recently the results of photochemical study and of quantum chemical calculations of new photochromic systems based on 2-(N-acyl-N-arylaminemethylene)-3(2 H)benzo [b]thiophenones with reversible acetyl groups migration were presented [1]. The mechanism of photochromic reaction proposed involves Ζ -* Ε isomerization of the initial compound, for example, (la) and…”

“…Recently the results of photochemical study and of quantum chemical calculations of new photochromic systems based on 2-(N-acyl-N-arylaminemethylene)-3(2 H)benzo [b]thiophenones with reversible acetyl groups migration were presented [1]. The mechanism of photochromic reaction proposed involves Ζ -* Ε isomerization of the initial compound, for example, (la) and…”

“…Although the ketoanime (I) structure of acylation products of initial 2-(N-arylaminomethylene)-3(2 H)-benzo[b]thiophenone [3] and enolimine(II) structure of their photoisomers have been reliably proved by chemical and spectral methods, the conclusions on conformational characteristics of the compounds (I) and (II), drawn earlier in [1], were based on less well-defined arguments. Preference of the Ζ (trans)-configuration (la) as opposed to the Ε (cis)-form (lb) follows from calculation of the heats of formation and the solvation energies for all possible planar conformations (la), (lb), by the SCF MO PPP method in the Dewar σ, π-parametrization [4] and also from studies of molecular geometry through use of shift reagents.…”

“…A considerable energy of activation (K25 ä 10~3s~') is required for a reverse reaction to procede in the dark. The heat of reaction in solutions, evaluated by quantum chemical calculations amounts to 8 -10 kcal/mole [1], These data suggest that the system under study may have potential in a number of abiotic chemical systems of accumulation and storage of solar energy (see reviews 2).…”

“…This paper presents the results of X-ray structural studies of 2-(N-acetyl-N-3-nitrophenylaminomethylene)-3(2 H)benzo[b]thiophenone (I, R 1 = CH3, R 2 = 3-N02) and the photoisomer N-(3-nitrophenyl)-3-acetoxy-2-benzo[b]-thiophenaldimine (II, R 1 = CH3, R 2 = 3-N02) obtained from the former by UV-irradiation in solution [1], from benzene solution of (la) after its exposure to Hg-lamp light for several minutes. The substances (la, II) crystallize in the form of thin yellow needles of monoclinic and rhombic crystal forms, respectively.…”