Polymethine Dye as Sensors of NH₃ and CO

Table 1

The calculated parameters of the molecules PMD.

Designations	R2-substituent in the PMD molecule	The long-wavelength absorption band, λ, nm	The oscillator strength
PMD cations (R1 = H)
PMD-I	OCF3	472.52	0.973
PMD-II	OCCl3	464.16	1.010
PMD-III	COOH	471.03	1.001
PMD-IV	NO2	464.80	1.050
Neutral PMD molecules (R1 = O)
PMD-V	OCF3	535.18	0.810
PMD-VI	OCCl3	528.24	0.854
PMD-VII	COOH	535.36	0.840
PMD-VIII	NO2	536.23	0.875