109735-91-3Relevant academic research and scientific papers
MO-LCAO Calculations on Sulfur-containing ?-Electron Systems. L. Synthesis and UV/VIS Spectral Properties of Derivatives of 1H-Perimidine-2-thion-carbonic Acid
Thiel, W.,Fabian, J.,Friebe, B.
, p. 812 - 823 (2007/10/02)
Esters of the 1H-perimidine-2-dithiocarbonic acid are easily accessible from 1.8-diamino-naphthalene and chloroacetyl chloride and subsequent thiolation of the reaction product under mild conditions and alkylation.The dithioesters react with aliphatic and aromatic amines to form thioamides.Both the resulting dithioesters and thioamides are clearly distinguished by their colour from the vast majority of known derivatives of thioncarbonic acids.While dithioesters and thioamides are generally red and yellow, respectively, in solution the corresponding derivatives of the 1H-perimidine are blue and red, respectively.The detailed examination of the experimental data has revealed that the colour determining longest wavelength absorption bands are due to the ?(*)?* rather than to the n(*)?* transitions.Due to the efficient mixing of the lowest energy locally excited (LE) state of the heterocyclic moiety and the lowest energy perimidine-to-substituent charge transfer (CT) state the low-intensity longwavelenght ?(*)?* transition of perimidine undergoes a pronounced red shift by acceptor substituents of high electron affinity in 2-position.This interpretation of the deep colour of the 1H-perimidine-2-thiocarbonic acid is in harmony with substituents effects and fully born out by Pariser-Parr-Pople (PPP) type calculations completed by additional analyses of electronic state (Baba-Suzuki-Takemura analysis) and electronic transitions (Ohta-Kuroda-Kunii analysis).
