CHEM01200604005 A. K. Pathak - Homi Bhabha National Institute

adical anion (CO 3 • ⎯) is found to be at 580 nm at TDDFT (B3LYP)/6-311++G(d,p) level
of theory.
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ε (M -1 cm -1 )
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ε (M -1 cm -1 )
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I
II
Fig. 5.3. (I) Optical absorption profile for (a) Cl 2•¯ and (b) Cl 2•¯.10H 2 O at CIS/6-311++G(d,p) level of
theory. (c) Experimental absorption profile for Cl 2•¯ in aqueous solution. (II) Optical absorption profile for
(a) the most stable structure of CO • 3 ⎯.8H 2 O at TDDFT/6-311++G(d,p) with B3LYP hybrid density
functional and (b) experimental absorption profile for CO • 3 ⎯ in aqueous solution.
The λ max values of the CO • 3 ⎯.nH 2 O clusters (n=1-8) calculated at the same level of
theory are supplied in Table 5.1. Visualization of the appropriate molecular orbital (MO)
indicates that the optical absorption is mainly due to an electronic transition from the
highest doubly occupied bonding sigma MO to the lowest singly occupied antibonding
sigma MO (σ→σ*) in all these hydrated clusters. The optical absorption profiles for each
of the CO • 3 ⎯.nH 2 O systems (n=0-8) are generated based on ten low lying excited states
and the UV-Vis spectra for CO •− 3 .8H 2 O systems is shown in Fig. 5.3-II(a). There is an
excellent agreement between the experimental aqueous phase optical absorption spectrum
(see Fig. 5.3-II(b)) and the present calculated one for the most stable structure of
CO • 3 ⎯.8H 2 O cluster. 60 The calculated absorbance is scaled with the reported experimental
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