Tuning Reactivity of Platinum(II) Complexes

The light transmitted from the sample can be represented as
I0
T = (2.33)
I
Where I 0 = the intensity of the incident light obtained from the solvent reference cell
I = the intensity of the transmitted light from the power source after passing
through the analyte cell
The absorbance can then be written as
A = −logT
(2.34)
By measuring the absorbance of the reaction mixture at specific time intervals or in a
continuous manner, the concentration-time-resolved spectrum of the system can be
determined from the Beer’s law (Equation 2.35). 30
A = εcl
(2.35)
where, A = absorbance
ε = molar absorptivity (L mol-1 cm-1 )
c = Concentration (mol dm-3 )
l = path length (cm)
UV-Visible absorption spectra usually contain broad absorptions that overlap with
other species in the solution, which makes the analysis of the product more difficult.
However, kinetic analysis can be done on overlapping absorption spectra. 6
For a given first-order reaction,
k 1
X Y
At any time t, the absorption is then given by
22
(2.36)
= ε [ X ] + ε [ Y ]
(2.37)
At X
Y
where, At = the absorbance at any time, t
ε X , εY
= molar absorptivity of X and Y respectively
Once the reaction goes to completion, the absorption is given by
ε + ε
A∞ = X [ X ] 0 Y [ Y ] 0
(2.38)
where A ∞ = absorbance upon completion of reaction