FULL PAPER * E-mail: samyeldaly@yahoo.com Received June 19, 2011; revised August 10, 2011; accepted August 25, 2011. Chin. J. Chem. 2011, 29, 2557—2561 © 2011 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 2557 Effect of Medium Acidity and Photostability of 3-(4-Dimethyl- amino-phenyl)-1-(2,5-dimethyl-thiophen-3-yl)-propenone (DDTP): A New Green Emitting Laser Dye El-Daly, Samy A.* ,a,b Asiri, Abdullah M. a,c Khan, Salman A. a Alamry, Khalid A. a Hussein, Mahmoud A. a,d a Chemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia b Department of Chemistry, Faculty of Science, Tanta University, 31527 Tanta, Egypt c The Center of Excellence for Advanced Materials, King Abdul Aziz University, Jeddah 21589, P.O. Box 80203, Saudi Arabia d Polymer Chemistry Lab, Chemistry Department, Faculty of Science, Assiut University, Assiut, 71516, Egypt On the line of a previous work on the spectral properties of some of heteroaryl chalcone, the effect of medium acidity and photoreactivity of 3-(4-dimethylamino-phenyl)-1-(2,5-dimethyl-thiophen-3-yl)-propenone (DDTP) has been investigated in dimethylformamide and in chloromethane solvents such as methylenechloride, chloroform and carbon tetrachloride. The dye solution (ca. 5×10 －4 mol•L －1 in DMF) gives a good laser emission in the range 470 —560 nm with emission maximum at 515 nm upon pumping by nitrogen laser (λ ex ＝337.1 nm). The laser parame- ters such as gain coefficient (α), emission cross section (σ e ) and half life energy (E 1/2 ) at maximum laser emission are also determined. Keywords 3-(4-dimethylamino-phenyl)-1-(2,5-dimethyl-thiophen-3-yl)-propenone, laser dyes, effect of acidity, possibility Introduction Chalcone derivatives have been reported earlier as important probes of medium viscosity. 1 This property is particularly important in assessing the microenviron- ments in micelles, microemulsions and vesicles. 2 Chal- cones are known as physiological active substances produced within tissues that appear to control the mito- sis of the cell of specific tissues that produce them. 3 Hetro-aryl chalcone derivatives have several applica- tions in many areas such as in food industry, 4 fluores- cent probes for sensing DNA 5 and photoreactive poly- mers. 6 Also, chalcones have been used for numerous optical applications including photo-alignment layer of liquid crystal display. 7 Therefore, the photophysical properties of chalcones containing alkyl amino group as electron donor have been studied. 8-11 In earlier studies 12-14 we reported the photophysical and laser emission from some aryl chalcones derivatives. This paper represents a continuation of our systematic studies of donor-acceptor aromatic derivatives separated by ethenyl bridge. We reported, the laser activity of another chalcone derivative namely 3-(4-dimethylamino-phenyl)-1-(2,5- demethyl-thiophen-3-yl)-propenone (DDTP). Experimental DDTP was synthesized and purified as described previously 15,16 and its purity was confirmed by elemen- tal analysis and 1 H NMR and 13 C NMR. All solvents used were of spectroscopic grade and were preliminarily checked for the absence of absorbing or fluorescent impurities within the scanned spectral ranges. UV-visi- ble electronic absorption spectra were recorded on Shi- madzu UV-160A spectrophotometer with band-pass of N CH 3 H 3 C S H 3 C CH 3 O N + CH 3 H 3 C S H 3 C CH 3 O - DDTP Ground state Excited state