title: Fluorescence, Photophysical Behaviour and DFT Investigation of E,E-2,5-bis[2-(3-pyridyl)ethenyl]pyrazine (BPEP).
abstract: E,E-2,5-bis[2-(3-pyridyl)ethenyl]pyrazine (BPEP) has been prepared by aldol condensation between 2,5-dimethylpyrazine and pyridine-3-carboxaldehyde. It is characterized by IR, (1)H NMR, and (13)C NMR. The electronic absorption and emission properties of BPEP were studied in different solvents. BPEP displays a slight solvatochromic effect of the absorption and emission spectrum, indicating a small change in dipole moment of BPEP upon excitation. The dye solutions (1 × 10(-4) M) in CHCl3, EtOH and dioxane give laser emission in blue region upon excitation by a 337.1 nm nitrogen pulse (λ = 337 nm). The tuning range, gain coefficient (α) and emission cross - section (σe) have been determined. Ground and excited states electronic geometric optimizations were performed using density functional theory (DFT) and time-dependent density functional theory (TD-DFT), respectively. A DFT natural bond analysis complemented the ICT. The simulated maximum absorption and emission wavelengths are in line the observed ones in trend, and are proportionally red-shifted with the increase of the solvent polarity. The stability, hardness and electrophilicity of BPEP in different solvents were correlated with the polarity of the elected solvents. BPEP dye displays fluorescence quenching by colloidal silver nanoparticles (AgNPs). The fluorescence data reveal that radiative and non-radiative 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.
authors.forename: Amerah M
authors.initials: AM
authors.lastname: Al-Soliemy
authors.affiliation: Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah, 21589, Saudi Arabia.|Chemistry Department, Faculty of Science, Khartoum University, P.O. Box 321, 11111, Khartoum, Sudan.
authors.forename: Osman I
authors.initials: OI
authors.lastname: Osman
authors.affiliation: Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah, 21589, Saudi Arabia.|Chemistry Department, Faculty of Science, Assiut University, Assiut, 71516, Egypt.
authors.forename: Mahmoud A
authors.initials: MA
authors.lastname: Hussein
authors.affiliation: Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah, 21589, Saudi Arabia. aasiri2@gmail.com.|Center of Excellence for Advanced Materials Research (CEAMR), King Abdulaziz University, P.O. Box 80203, Jeddah, 21589, Saudi Arabia. aasiri2@gmail.com.
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. samyeldaly@yahoo.com.|Chemistry Department, Faculty of Science, Tanta University, Tanta, 2173, Egypt. samyeldaly@yahoo.com.
authors.forename: Samy A
authors.initials: SA
authors.lastname: El-Daly
keywords: E,E-2,5-bis[2-(3-pyridyl)ethenyl]pyrazine; Effect of solvent; Fluorescence quenching; Photophysical properties