A semi-empirical estimation of ground and excited state dipole moments of zinc phthalocyanine from solvatochromic shift data

Abstract

<jats:p>A semi-empirical determination of ground and excited state dipole moments of zinc phthalocyanine (ZnPc) from solvatochromic shifts is hereby presented. The ratio of the excited- and ground-state dipole moments of ZnPc ( ) was estimated by a combination of the Bakshiev and the Kawski-Chamma-Viallet’s equations, while the difference in the excited- and ground-state dipole moments (Dm) was estimated usingthe molecular-microscopic solvent polarity parameters ( ), alongside the Stokes’ shifts (Dῡ) in the various solvents. The dipole moment of ZnPc is significantly higher in the excited singlet state (me = 3.12 D) than in the ground state (mg = 1.50 D). Obviously charge separation is greater in the excited state of ZnPc than in its ground state. </jats:p>

Evaluation of Ground and Excited State Dipole Moments of 2(3)-tetra(tert-butylphenoxy)phthalocyaninato Zinc(II) from Solvatochromic Data

“…( It is of interest to note that the values of g and e determined for ZnTBPc are significantly greater than those obtained for ZnPc (g=1.50D; e=3.12D) in an earlier work [19]. In ZnPc, it was suggested that the drop in symmetry from D4h to C4v in the molecule is responsible for its observed polarity.…”

“…However, literature is very scanty on the use of solvent-induced shifts for the determination of dipole moments of Pcs. In the present study, a semi -empirical estimation of the ground and excited-state dipole moments of 2(3)-tetra(tertbutylphenoxy)phthalocyaninato zinc(II) is presented using the solvatochromic shift method [18][19][20][21], which is based on the Onsager's reaction field theory [22].…”