Mk. Shukla et Pc. Mishra, ELECTRONIC-STRUCTURE, SPECTRA AND EXCITED-STATE PROPERTIES OF N,N-DIMETHLYLAMINOGUANINE, SPECT ACT A, 54(7), 1998, pp. 937-946
Citations number
43
Categorie Soggetti
Spectroscopy
Journal title
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
An experimental and ah initio theoretical study has been performed on
the electronic spectra and structure of N.N-dimethylaminoguanine (DMAG
). The experimental work included study of absorption and fluorescence
spectra at different pH in aqueous solution while the theoretical stu
dy included SCF-CIS ab initio gas phase computations of ground and exc
ited state geometries and electronic transitions of the molecule. Vert
ical transitions from the optimised ground state of the molecule were
also studied theoretically under solvation in water using the polarize
d continuum model (PCM). It has been shown that at the neutral and aci
dic pH (similar to 3); the molecule would exist in the ground state in
the keto-N9H form while at alkaline pH (similar to 11), it would main
ly occur in the anionic form deprotonated at the N, site. Further, the
molecule seems to get deprotonated in the lowest singlet pi-pi excit
ed state even at the neutral pH. Molecular electrostatic potential map
ping was performed in the ground and lowest two singlet excited states
of the keto-N9H form of the molecule in order to study the mechanism
of its phototautomerism to the keto-N7H form which appears to he impor
tant from the point of view of fluorescence. (C) 1998 Elsevier Science
B.V. All rights reserved.