title: Two-photon absorption properties of iron(II) and ruthenium(II) trischelate complexes of 2,2':4,4' ':4',4' ''-quaterpyridinium ligands.
abstract: A series of RuII or FeII trischelate complex salts containing N-methyl/aryl-2,2':4,4' ':4',4' ''-quaterpyridinium ligands that has previously been subjected to quadratic nonlinear optical studies (Coe, B. J. et al. J. Am. Chem. Soc. 2005, 127, 13399) has now been investigated for two-photon absorbing behavior. Z-scan measurements using a 750 nm laser afford reasonably large two-photon absorption (2PA) cross-sections sigma2 of ca. 62-180 GM for the RuII complexes, but only very weak 2PA is observed for the FeII compounds. The excited-state and 2PA properties of the representative chromophore [RuII(Me2Qpy2+)3]8+ (Me2Qpy2+=N' ',N' ''-dimethyl-2,2':4,4' ':4',4' ''-quaterpyridinium) have also been investigated by using semiempirical intermediate neglect of differential overlap/multireference-determinant single and double configuration interaction computations with the optimized geometry obtained via density functional theory. The calculated sigma2 value of ca. 624 GM at 1.70 eV for this metal-to-ligand charge-transfer chromophore is about 10 times larger than that obtained from the Z-scan studies.
authors.affiliation: School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK. b.coe@manchester.ac.uk
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Coe
authors.forename: Marek
authors.initials: M
authors.lastname: Samoc
authors.forename: Anna
authors.initials: A
authors.lastname: Samoc
authors.forename: Lingyun
authors.initials: L
authors.lastname: Zhu
authors.forename: Yuanping
authors.initials: Y
authors.lastname: Yi
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Shuai