title: Photoactive azoimine dyes: 4-(2-pyridylazo)-N,N-diethylaniline and 4-(2-pyridylazo)-N,N-dimethylaniline: computational and experimental investigation.
abstract: 4-(2-Pyridylazo)-N,N-dimethylaniline and 4-(2-pyridylazo)-N,N-diethylaniline, two photoactive azoimine dyes, were prepared from the reaction of 2-aminopyridine with N,N-dialkyl-1,4-nitrosoaniline at room temperature. Structural characterizations of these dyes using single crystal X-ray diffraction, (1)H NMR, elemental analysis, mass spectroscopy and IR spectroscopy have been carried out. The X-ray structure indicates a trans configuration around the azo group. The photochemical behavior of these compounds differs from that of 2-phenylazopyridine, the non-dialkylamino substituent compound. The synthesized compounds show emission spectra at room temperature while 2-phenylazopyridine does not. The excitation spectra of these compounds differ from their absorption spectra which can be explained on the basis of the trans to cis photoisomerization which is supported by the TD-PBE0/6-31G(d,p) calculations. Both oxidation of the dialkylamino substituents (-NR(2); R=-CH(3) and -C(2)H(5)) and reduction of -N=N-/-N=N-(-) and -N=N-(-)/-N=N-(2-) were observed in the cyclic voltammogram indicating a π-acidity of both dyes.
authors.affiliation: Department of Chemistry and Center for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand.
authors.forename: Suthirat
authors.initials: S
authors.lastname: Yoopensuk
authors.forename: Pornthip
authors.initials: P
authors.lastname: Tongying
authors.forename: Kanidtha
authors.initials: K
authors.lastname: Hansongnern
authors.forename: Chaveng
authors.initials: C
authors.lastname: Pakawatchai
authors.forename: Saowanit
authors.initials: S
authors.lastname: Saithong
authors.forename: Yuthana
authors.initials: Y
authors.lastname: Tantirungrotechai
authors.forename: Nararak
authors.initials: N
authors.lastname: Leesakul
mesh_terms: D000042:Absorption / Q000528:radiation effects; D000814:Aniline Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D004396:Coloring Agents / Q000737:chemistry*; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D055664:Electrochemical Techniques; D008027:Light; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D055620:Optical Phenomena; D011725:Pyridines / Q000737:chemistry*; D011789:Quantum Theory; D012997:Solvents / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet
chemical_list: C571501:4-(2-pyridylazo)-N,N-diethylaniline; C571500:4-(2-pyridylazo)-N,N-dimethylaniline; D000814:Aniline Compounds; D004396:Coloring Agents; D011725:Pyridines; D012997:Solvents; C110696:N,N-diethylaniline; C015157:N,N-dimethylaniline