Charge-transfer interactions between piperidine as donor with different sigma- and pi-acceptors: Synthesis and spectroscopic characterization

Charge-transfer (CT) complexes formed between piperidine (Pip) as donor with mono-iodobromide (IBr), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), 2,6-dichloroquinone-4-chloroimide (DCQ), and 2,6-dibromoquinone-4-chloroimide (DBQ), as acceptors have been studied spectrophotometrically. The synthesis and characterization of piperidine CT-complexes of mono-iodobromide, {[}(Pip)(IBr)], 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, {[}(Pip)(DDQ)], 2,6-dichloroquinone-4-chloroimide, {[}(Pip)(DCQ)] and 2,6-dibromoquinone-4-chloroimide, {[}(Pip)(DBQ)] were described. These complexes are readily prepared from the reaction of Pip with IBr, DDQ, DCQ and DBQ within CHCl3 solvent. IR, UV-Vis techniques and elemental analyses (CHN), characterize the four piperidine charge-transfer complexes. Benesi-Hildebrand and its modification methods were applied to the determination of association constant (K), molar extinction coefficient (epsilon). (C) 2010 King Saud University. All rights reserved.