Spectral and thermodynamic properties for the exciplexes of N-alkyl carbazoles with dicyanobenzenes in THF.
The exciplex emission spectra of N-ethylcarbazole with 1,2-dicyanobenzene (NEC/1,2-DCB), N-methylcarbazole with 1,2-dicyanobenzene (NMC/1,2-DCB), 1,3-dicyanobenzene (NMC/1,3-DCB), and 1,4-dicyanobenzene (NMC/1,4-DCB) are studied in tetrahydrofuran (THF) for the temperature range starting from 253 K to 334 K. Thermochromic shifts along with the spectral properties including change in peak intensities and the ratio of exciplex peak intensity to fluorophore peak intensity are studied. Effect of temperature on the energy of zero-zero transitions hνo('), Huang-Rhys factor (S), Gauss broadening of vibronic level (σ) and the dominant high-frequency vibration (hνν) are also part of investigation. Enthalpy of exciplex formation (ΔH(EX)(∗)) calculated by the model proposed by A. Weller and the Gibb's energy of electron transfer (ΔG(et)(∗)) for all exciplex systems are also discussed in the present paper. All the exciplexes under study were observed to be dipolar in nature. The exciplex of the N-methylcarbazole/1,4-dicyanobenzene was found to be the most stable and the N-methylcarbazole/1,3-dicyanobenzene was the weakest exciplex system.
Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria; Department of Chemistry and Biochemistry, University of Agriculture, Faisalabad, Pakistan(1). Electronic address: sadia1asim@gmail.com.
Sadia
S
Asim
Asim
A
Mansha
Stephan
S
Landgraf
Günter
G
Grampp
Muhammad
M
Zahid
Haq Nawaz
HN
Bhatti
D002227:Carbazoles / Q000737:chemistry*; D004583:Electrons; D005456:Fluorescent Dyes / Q000737:chemistry; D005663:Furans / Q000737:chemistry*; D009570:Nitriles / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics
D002227:Carbazoles; D005456:Fluorescent Dyes; D005663:Furans; D009570:Nitriles; C041514:carbazole; C018674:tetrahydrofuran
Photoinduced electron transfer; Solvatochromic shifts; Spectral intensity; Thermochromic shifts; Thermodynamic parameters