title: Spectroscopic investigation, photophysical parameters and DFT calculations of 4,4'-(1E,1'E)-2,2'-(pyrazine-2,5-diyl)bis(ethene-2,1-diyl)bis(N,N-dimethylaniline) (PENDA) in different solvents.
abstract: A comprehensive investigation on the photophysics of a π-conjugated potential push-pull chromophore system 4,4'-(1E,1'E)-2,2'-(Pyrazine-2,5-diyl)bis(ethene-2,1-diyl)bis(N,N-dimethylaniline) (PENDA) has been carried out spectroscopically. The optical absorption and emission properties of this molecule have been studied in different solvents. The molecule PENDA shows strong solvatochromic emission upon changing the solvent polarity from nonpolar to polar; indicating that emission state is of intramolecular charge transfer (ICT) character. The solvent effect on the spectral properties such as singlet absorption, molar absorptivity, oscillator strength, dipole moment and fluorescence quantum yield of PENDA have been studied in detail. Lippert-Mataga and Reichardt correlations were used to estimate the difference between the excited and ground state dipole moments (Δμ). Ground and electronic excited states geometric optimizations were performed using density functional theory (DFT) and time-dependent density functional theory (TDDFT), respectively, with the Gaussian 09 package. A solution of (8×10(-5) M) PENDA in THF, dioxane, CH3CN and CHCl3 gives laser emission when pumped by a nitrogen laser pulse (λex=337.1 nm) of 800 ps duration and 1.48 mJ pulse energy. PENDA dye displays fluorescence quenching by colloidal silver nanoparticles (Ag NPs) in ethanol. The fluorescence data reveal that dynamic quenching and energy transfer play a major role in the fluorescence quenching mechanism.
authors.affiliation: Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia; Center of Excellence for Advanced Materials Research, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia.
authors.forename: Abdullah M
authors.initials: AM
authors.lastname: Asiri
authors.affiliation: Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia.
authors.forename: Khalid A
authors.initials: KA
authors.lastname: Alamry
authors.affiliation: Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia.
authors.forename: Mehboobali
authors.initials: M
authors.lastname: Pannipara
authors.affiliation: Research Center for Advanced Materials Science (RCAMS), King Khalid University, P.O. Box 9004, Abha 61413, Saudi Arabia.
authors.forename: Abdullah G
authors.initials: AG
authors.lastname: Al-Sehemi
authors.affiliation: Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia. Electronic address: samyeldaly@yahoo.com.
authors.forename: Samy A
authors.initials: SA
authors.lastname: El-Daly
keywords: DFT; Effect of solvent; Fluorescence quantum yield; Silver nanoparticles; Styryl pyrazine