Syntheses, molecular and crystalline architectures, and luminescence behaviour of terephthalate bridged heptacoordinated dinuclear lead(II) complexes containing a pentadentate N-donor Schiff base

• Published in: Journal of chemical sciences (Bangalore, India) Vol. 125; no. 4; pp. 715 - 721
• Main Authors: ROY, SUBHASIS, CHOUBEY, SOMNATH, KHAN, SUMITAVA, BHAR, KISHALAY, MITRA, PARTHA, GHOSH, BARINDRA KUMAR
• Format: Journal Article
• Language: English
• Published: India Springer India 01.07.2013
• Subjects: Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Schiff base; hemidirected structures; luminescence; terephthalate bridge; Dinuclear lead(II)
• ISSN: 0974-3626; 0973-7103
• DOI: 10.1007/s12039-013-0435-5

One-pot synthesis using a 2:2:1:2 molar ratio of Pb(OAc) 2 ·3H 2 O, L, piperidinum terephthalate (ptp) and NaClO 4 /NH 4 PF 6 at room temperature affords two dinuclear compounds of the type [Pb 2 (L) -tp)](ClO 4 /PF 6 ) 2 ( 1/2 ) [L=N,N ′ -(bis-(pyridin-2-yl)benzylidene)diethylenetriamine and tp = terephthalate dianion]. The compounds are characterized by microanalytical, spectroscopic, thermal and other physicochemical results. X-ray structural analyses of 1 and 2 reveal that each heptacoordinated lead(II) centre with a PbN 5 O 2 chromophore are bound by five N atoms of L and connected through O atoms of a bis(bidentate) tp bridge. The arrangements of L and tp suggest a gap around the metal centre due to occupation of a stereo-active lone pair of electrons reflecting a hemidirected coordination around the metal centre. The complexes exhibit reasonable thermal stabilities with the tolerate temperatures ca. 255°C for 1 and 263°C for 2 . The complexes display intraligand ( π - π *) fluorescence in the solid state and in DMF solutions at room temperature. Graphical Abstract Two dinuclear lead(II) compounds are isolated and X-ray crystallographically characterized. Each heptacoordinated metal(II) center adopts a hemidirected environment and connected through bis(bidentate) terephthalate bridge. The complexes exhibit intraligand 1 ( π - π *) fluorescence in the solid state and in DMF solutions at room temperature.