STRUCTURE OF TWO QUINOLONES AND A STUDY ON LASING EFFICIENCY OF THESE COMPOUNDS. Sudha Lakshmanan, Kulandavelu Subramanian, Dept.Physics, Anna University,Madras-600025.India, Gertraud Koellner and Thomas Steiner, Institute for Crystallography,Freie University Takustrasse 6, D-14159, Berlin, Germany

The crystal and molecular structure of two dyes namely (1)5-(amino)-8- methyl-2-quinolone monohydrate and (ii)5-(Isopropylamino)-8-methyl-2- quinolone are carried out to understand the dependent of the lasing efficiency on the molecular conformation of these dyes. Quinolone ring system is essentially planar. The crystal structures are stablised by O-H..O, N-H..O, N-H..N, and C-H..0 interactions. Absorption and fluorescence spectra were recorded with these compounds and compared with those of commercial dye. Lasing activity of these compounds has been studied with the help of three dimentional structure of the molecules.

Quinolone (I)[C₁₂H_l4N₂O]: Space group P2₁/n a= 14.117(5),b=8.628(2),c=8.766(2)deg.Å ß=93.91 deg.(1),Z=4,V= 1065.2(5). D_x- 1.26Mgm^-3, u=0.62mm^-l. Of the 1692 measured reflections 1573 were observed [l>3[[sigma]](I)]. The final R-factor R=0.0631 and wR=0.1825. Quinolone(II) [C₁₃H₁₆N₂O.H₂O]: Space group=P , a=8.094(2), b=11.647(2), c=13.644(3)deg.Å, [[alpha]]=96.52deg.(3), ß=92.87deg.(3), [[gamma]]=106.21deg.(3) Z=2, V= 1222.6(5), D_x= 1.22Mgm^-3. u=0.61mm^-1 R=0.0651 and wR=0.1856.