The Substitutent Effect On The Spectra And Molecular Configuration Of The Ethynylaniline

Aniline derivatives are not only an important organic dyes, and has strong fluorescence performance and stability. Amines contain one of the simplest auxochrome, i.e., amino(-NH2). Therefore, aniline and its substituents are deemed to be good candidates to modeling the photochemistry along the amino moiety in the purine derived DNA bases guanine and adenine, while many substituent aniline have long been considered as a basis for deeply understanding intramolecular charge-transfer(ICT) dynamics in more complex species. Up to now, numerous experimental and theoretical investigations have studied aniline’s spectroscopy. However, the information about the ethynyl substituted aniline are rarely explored. The electronic absorption and emission of molecules are complicated microscopic processes between the ground state and excited states transition. With the development of computing technology, computational chemistry methods to describe the molecular structure and properties of the ground state is sufficient. While the researches on the structures of properties of the excited states are still developing. The electronic excited states of molecules are unstable, they usually release the energy and return to the ground state in many kinds forms. So it is difficult for experiment to obtain reliable information about the excited states of molecules. The advantages of theoretical study are powerful complements to the experiment, indicative of theoretical forward looking and independence. With the development of spectroscopy and ab initio quantum chemistry, theoretical method and experimental technology influence each other, promote each other, and makes the description of the excited states toward the direction of higher precision.In the present paper, we provide an extended study on the structure and properties of the low-lying electronic states of ethynyl substituted aniline and their cations. We performed these calculations using the DFT and TDDFT methods on Gaussian 09 combined the aug-cc-pVTZ basis set and the CASSCF/CASPT2 approach in connecting with the concerted ANO-L-VDZP basis set on the MOLCAS 7.8. Our results include their equilibrium geometries, the vertical excitation spectra and the vertical and adiabatic ionization energies. The effect substitution by the ethynyl group on the electronic structure and the spectroscopy of the aniline is probed.